\quad\\[0.5cm] \boldmath Observation of $\bp \to \pppi$, $\bz \to \ppkz$, and $\bp \to \ppkst$
M.-Z.~Wang
We report the first observation of a $b\to u$ type charmless baryonic $B$ decay, $\bp \to \pppi$, as well as $b\to s$ type $\bz \to \ppkz$ and $\bp \to \ppkst$ decays. The analysis is based on a 78~fb$^{-1}$ data sample recorded on the $\Upsilon({4S})$ resonance with the Belle detector at KEKB. %The branching fractions We find ${\mathcal B}(\bp \to \pppi) = ( 3.06^{+0.73}_{-0.62} \pm 0.37) \times 10^{-6}$, ${\mathcal B}(B^0 \to \ppkz) = (1.88^{+0.77}_{-0.60} \pm 0.23) \times 10^{-6}$, and ${\mathcal B}(\bp \to \ppkst) = ( 10.3^{+3.6 + 1.3}_{-2.8 -1.7} ) \times 10^{-6}$. % for $m_{p\bar p < 2.85$ GeV. We also update ${\mathcal B}(\bp \to \ppk) = (5.66^{+0.67}_{-0.57} \pm 0.62 )\times 10^{-6}$, and present an upper limit on ${\mathcal B}(\bz \to \ppksz)$ at the 90\% confidence level. %, ${\mathcal B}(\bz \to \ppksz) < 7.6 \times 10^{-6}$. % A common feature of the observed decay modes is threshold peaking in baryon pair invariant mass. % \pacs{13.25.Hw, 13.60.Rj}
lp03pph.tex
\documentclass[aps,prl,preprint,tightenlines,superscriptaddress,showpacs,byrevtex]{revtex4}
\usepackage{dcolumn}  % Align table columns on decimal point
\renewcommand{\arraystretch}{1.1}
\usepackage{epsfig}% Include figure files
\newcommand{\mpp}{M_{p\bar{p}}}
\newcommand{\mb}{{M_{\rm bc}}}
\newcommand{\de}{{\Delta{E}}}
\newcommand{\bp}{{B^{+}}}
\newcommand{\bz}{{B^{0}}}
\newcommand{\pp}{{p\bar{p}}}
\newcommand{\ppk}{{p\bar{p}K^+}}
\newcommand{\pppi}{{p\bar{p}\pi^+}}
\newcommand{\ppkz}{{p\bar{p}K^0}}
\newcommand{\ppks}{{p\bar{p}K_S^0}}
\newcommand{\ppkst}{{p\bar{p}K^{* +}}}
\newcommand{\ppksz}{{p\bar{p}K^{*0}}}
\newcommand{\plpi}{{p\bar{\Lambda}\pi^-}}
\newcommand{\plk}{{p\bar{\Lambda}K^-}}
\newcommand{\psigpi}{{p\bar{\Sigma}^0\pi^-}}
\newcommand{\kst}{{K^{*{+}}}}
\newcommand{\ksz}{{K^{*0}}}
\newcommand{\ks}{{K_S^0}}
\newcommand{\kz}{{K^0}}
\begin{document}
\preprint{\vbox{ \hbox{   }
%                 \hbox{draft V8}
                  \hbox{Belle preprint 2003-23}
%                 \hbox{EPS Parallel Sessions: 3, 10, 12}
%                 \hbox{EPS-ID 531}
%                 \hbox{hep-ex/0302024}
}}
\title{ \quad\\[0.5cm]
\boldmath Observation of $\bp \to \pppi$, $\bz \to \ppkz$, and
$\bp \to \ppkst$}


%% >>>> Insert final authorlist here

%%% Paper:    B -> p pbar h(*)
%%% Journal:  Physical Review Letters
%%% Contacts: M. Wang (mwang@phys.ntu.edu.tw)
%%%           P. Chu (pinghan@hep1.phys.ntu.edu.tw)
%%% Non-responding authors or those who said NO are commented out.
%%% ====================================================================
%%% Click the RELOAD button on your web browser to see the updated file.
%%% ====================================================================
%%% Use \input{author} to insert this material into your latex file.
%%%%% Force institutions to appear in alphabetical order when typeset.
%\affiliation{Aomori University, Aomori}
\affiliation{Budker Institute of Nuclear Physics, Novosibirsk}
\affiliation{Chiba University, Chiba}
%\affiliation{Chuo University, Tokyo}
\affiliation{University of Cincinnati, Cincinnati, Ohio 45221}
\affiliation{University of Frankfurt, Frankfurt}
\affiliation{Gyeongsang National University, Chinju}
\affiliation{University of Hawaii, Honolulu, Hawaii 96822}
\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba}
\affiliation{Hiroshima Institute of Technology, Hiroshima}
\affiliation{Institute of High Energy Physics, Chinese Academy of Sciences, Beijing}
\affiliation{Institute of High Energy Physics, Vienna}
\affiliation{Institute for Theoretical and Experimental Physics, Moscow}
\affiliation{J. Stefan Institute, Ljubljana}
\affiliation{Kanagawa University, Yokohama}
\affiliation{Korea University, Seoul}
%\affiliation{Kyoto University, Kyoto}
\affiliation{Kyungpook National University, Taegu}
\affiliation{Institut de Physique des Hautes \'Energies, Universit\'e de Lausanne, Lausanne}
\affiliation{University of Ljubljana, Ljubljana}
\affiliation{University of Maribor, Maribor}
\affiliation{University of Melbourne, Victoria}
\affiliation{Nagoya University, Nagoya}
\affiliation{Nara Women's University, Nara}
%\affiliation{National Kaohsiung Normal University, Kaohsiung}
\affiliation{National Lien-Ho Institute of Technology, Miao Li}
\affiliation{Department of Physics, National Taiwan University, Taipei}
\affiliation{H. Niewodniczanski Institute of Nuclear Physics, Krakow}
\affiliation{Nihon Dental College, Niigata}
\affiliation{Niigata University, Niigata}
\affiliation{Osaka City University, Osaka}
\affiliation{Osaka University, Osaka}
\affiliation{Panjab University, Chandigarh}
\affiliation{Peking University, Beijing}
\affiliation{Princeton University, Princeton, New Jersey 08545}
\affiliation{RIKEN BNL Research Center, Upton, New York 11973}
\affiliation{Saga University, Saga}
\affiliation{University of Science and Technology of China, Hefei}
\affiliation{Seoul National University, Seoul}
\affiliation{Sungkyunkwan University, Suwon}
\affiliation{University of Sydney, Sydney NSW}
\affiliation{Tata Institute of Fundamental Research, Bombay}
\affiliation{Toho University, Funabashi}
\affiliation{Tohoku Gakuin University, Tagajo}
\affiliation{Tohoku University, Sendai}
\affiliation{Department of Physics, University of Tokyo, Tokyo}
\affiliation{Tokyo Institute of Technology, Tokyo}
\affiliation{Tokyo Metropolitan University, Tokyo}
\affiliation{Tokyo University of Agriculture and Technology, Tokyo}
\affiliation{Toyama National College of Maritime Technology, Toyama}
\affiliation{University of Tsukuba, Tsukuba}
\affiliation{Utkal University, Bhubaneswer}
\affiliation{Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061}
\affiliation{Yokkaichi University, Yokkaichi}
\affiliation{Yonsei University, Seoul}
  \author{M.-Z.~Wang}\affiliation{Department of Physics, National Taiwan University, Taipei} % Taiwan
  \author{K.~Abe}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
  \author{K.~Abe}\affiliation{Tohoku Gakuin University, Tagajo} % TohokuGakuin
% \author{N.~Abe}\affiliation{Tokyo Institute of Technology, Tokyo} % TIT
  \author{T.~Abe}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
  \author{I.~Adachi}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
  \author{H.~Aihara}\affiliation{Department of Physics, University of Tokyo, Tokyo} % Tokyo
% \author{M.~Akatsu}\affiliation{Nagoya University, Nagoya} % Nagoya
% \author{M.~Asai}\affiliation{Hiroshima Institute of Technology, Hiroshima} % Hiroshima
  \author{Y.~Asano}\affiliation{University of Tsukuba, Tsukuba} % Tsukuba
  \author{T.~Aso}\affiliation{Toyama National College of Maritime Technology, Toyama} % Toyama
  \author{V.~Aulchenko}\affiliation{Budker Institute of Nuclear Physics, Novosibirsk} % BINP
  \author{T.~Aushev}\affiliation{Institute for Theoretical and Experimental Physics, Moscow} % ITEP
% \author{S.~Bahinipati}\affiliation{University of Cincinnati, Cincinnati, Ohio 45221} % Cincinnati
  \author{A.~M.~Bakich}\affiliation{University of Sydney, Sydney NSW} % Sydney
% \author{Y.~Ban}\affiliation{Peking University, Beijing} % Peking
% \author{E.~Banas}\affiliation{H. Niewodniczanski Institute of Nuclear Physics, Krakow} % Krakow
% \author{S.~Banerjee}\affiliation{Tata Institute of Fundamental Research, Bombay} % Tata
  \author{A.~Bay}\affiliation{Institut de Physique des Hautes \'Energies, Universit\'e de Lausanne, Lausanne} % Lausanne
% \author{I.~Bedny}\affiliation{Budker Institute of Nuclear Physics, Novosibirsk} % BINP
  \author{I.~Bizjak}\affiliation{J. Stefan Institute, Ljubljana} % Ljubljana
  \author{A.~Bondar}\affiliation{Budker Institute of Nuclear Physics, Novosibirsk} % BINP
  \author{A.~Bozek}\affiliation{H. Niewodniczanski Institute of Nuclear Physics, Krakow} % Krakow
  \author{M.~Bra\v cko}\affiliation{University of Maribor, Maribor}\affiliation{J. Stefan Institute, Ljubljana} % Ljubljana
% \author{J.~Brodzicka}\affiliation{H. Niewodniczanski Institute of Nuclear Physics, Krakow} % Krakow
  \author{T.~E.~Browder}\affiliation{University of Hawaii, Honolulu, Hawaii 96822} % Hawaii
% \author{B.~C.~K.~Casey}\affiliation{University of Hawaii, Honolulu, Hawaii 96822} % Hawaii
  \author{M.-C.~Chang}\affiliation{Department of Physics, National Taiwan University, Taipei} % Taiwan
  \author{P.~Chang}\affiliation{Department of Physics, National Taiwan University, Taipei} % Taiwan
  \author{Y.~Chao}\affiliation{Department of Physics, National Taiwan University, Taipei} % Taiwan
  \author{K.-F.~Chen}\affiliation{Department of Physics, National Taiwan University, Taipei} % Taiwan
  \author{B.~G.~Cheon}\affiliation{Sungkyunkwan University, Suwon} % Sungkyunkwan
  \author{R.~Chistov}\affiliation{Institute for Theoretical and Experimental Physics, Moscow} % ITEP
  \author{S.-K.~Choi}\affiliation{Gyeongsang National University, Chinju} % Gyeongsang
  \author{Y.~Choi}\affiliation{Sungkyunkwan University, Suwon} % Sungkyunkwan
  \author{Y.~K.~Choi}\affiliation{Sungkyunkwan University, Suwon} % Sungkyunkwan
  \author{P.~H.~Chu}\affiliation{Department of Physics, National Taiwan University, Taipei} % Taiwan
  \author{A.~Chuvikov}\affiliation{Princeton University, Princeton, New Jersey 08545} % Princeton
  \author{M.~Danilov}\affiliation{Institute for Theoretical and Experimental Physics, Moscow} % ITEP
% \author{M.~Dash}\affiliation{Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061} % VPI
  \author{L.~Y.~Dong}\affiliation{Institute of High Energy Physics, Chinese Academy of Sciences, Beijing} % IHEP
% \author{R.~Dowd}\affiliation{University of Melbourne, Victoria} % Melbourne
% \author{J.~Dragic}\affiliation{University of Melbourne, Victoria} % Melbourne
  \author{A.~Drutskoy}\affiliation{Institute for Theoretical and Experimental Physics, Moscow} % ITEP
  \author{S.~Eidelman}\affiliation{Budker Institute of Nuclear Physics, Novosibirsk} % BINP
  \author{V.~Eiges}\affiliation{Institute for Theoretical and Experimental Physics, Moscow} % ITEP
% \author{Y.~Enari}\affiliation{Nagoya University, Nagoya} % Nagoya
% \author{D.~Epifanov}\affiliation{Budker Institute of Nuclear Physics, Novosibirsk} % BINP
% \author{C.~W.~Everton}\affiliation{University of Melbourne, Victoria} % Melbourne
% \author{F.~Fang}\affiliation{University of Hawaii, Honolulu, Hawaii 96822} % Hawaii
% \author{H.~Fujii}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
  \author{C.~Fukunaga}\affiliation{Tokyo Metropolitan University, Tokyo} % TMU
  \author{N.~Gabyshev}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
  \author{A.~Garmash}\affiliation{Budker Institute of Nuclear Physics, Novosibirsk}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % BINP+KEK
  \author{T.~Gershon}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
  \author{G.~Gokhroo}\affiliation{Tata Institute of Fundamental Research, Bombay} % Tata
  \author{B.~Golob}\affiliation{University of Ljubljana, Ljubljana}\affiliation{J. Stefan Institute, Ljubljana} % Ljubljana
% \author{A.~Gordon}\affiliation{University of Melbourne, Victoria} % Melbourne
% \author{M.~Grosse~Perdekamp}\affiliation{RIKEN BNL Research Center, Upton, New York 11973} % RIKEN
% \author{H.~Guler}\affiliation{University of Hawaii, Honolulu, Hawaii 96822} % Hawaii
% \author{R.~Guo}\affiliation{National Kaohsiung Normal University, Kaohsiung} % Kaohsiung
% \author{J.~Haba}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
% \author{C.~Hagner}\affiliation{Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061} % VPI
% \author{F.~Handa}\affiliation{Tohoku University, Sendai} % Tohoku
% \author{K.~Hara}\affiliation{Osaka University, Osaka} % Osaka
  \author{T.~Hara}\affiliation{Osaka University, Osaka} % Osaka
% \author{Y.~Harada}\affiliation{Niigata University, Niigata} % Niigata
% \author{N.~C.~Hastings}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
% \author{K.~Hasuko}\affiliation{RIKEN BNL Research Center, Upton, New York 11973} % RIKEN
  \author{H.~Hayashii}\affiliation{Nara Women's University, Nara} % Nara
  \author{M.~Hazumi}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
% \author{E.~M.~Heenan}\affiliation{University of Melbourne, Victoria} % Melbourne
% \author{I.~Higuchi}\affiliation{Tohoku University, Sendai} % Tohoku
% \author{T.~Higuchi}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
% \author{L.~Hinz}\affiliation{Institut de Physique des Hautes \'Energies, Universit\'e de Lausanne, Lausanne} % Lausanne
% \author{T.~Hirai}\affiliation{Tokyo Institute of Technology, Tokyo} % TIT
% \author{T.~Hojo}\affiliation{Osaka University, Osaka} % Osaka
  \author{T.~Hokuue}\affiliation{Nagoya University, Nagoya} % Nagoya
  \author{Y.~Hoshi}\affiliation{Tohoku Gakuin University, Tagajo} % TohokuGakuin
% \author{K.~Hoshina}\affiliation{Tokyo University of Agriculture and Technology, Tokyo} % TUAT
  \author{W.-S.~Hou}\affiliation{Department of Physics, National Taiwan University, Taipei} % Taiwan
% \author{Y.~B.~Hsiung}\altaffiliation[on leave from ]{Fermi National Accelerator Laboratory, Batavia, Illinois 60510}\affiliation{Department of Physics, National Taiwan University, Taipei} % Taiwan
  \author{H.-C.~Huang}\affiliation{Department of Physics, National Taiwan University, Taipei} % Taiwan
% \author{T.~Igaki}\affiliation{Nagoya University, Nagoya} % Nagoya
% \author{Y.~Igarashi}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
% \author{T.~Iijima}\affiliation{Nagoya University, Nagoya} % Nagoya
  \author{K.~Inami}\affiliation{Nagoya University, Nagoya} % Nagoya
  \author{A.~Ishikawa}\affiliation{Nagoya University, Nagoya} % Nagoya
% \author{H.~Ishino}\affiliation{Tokyo Institute of Technology, Tokyo} % TIT
  \author{R.~Itoh}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
% \author{M.~Iwamoto}\affiliation{Chiba University, Chiba} % Chiba
  \author{H.~Iwasaki}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
  \author{M.~Iwasaki}\affiliation{Department of Physics, University of Tokyo, Tokyo} % Tokyo
  \author{Y.~Iwasaki}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
% \author{M.~Jones}\affiliation{University of Hawaii, Honolulu, Hawaii 96822} % Hawaii
% \author{R.~Kagan}\affiliation{Institute for Theoretical and Experimental Physics, Moscow} % ITEP
% \author{H.~Kakuno}\affiliation{Tokyo Institute of Technology, Tokyo} % TIT
% \author{J.~Kaneko}\affiliation{Tokyo Institute of Technology, Tokyo} % TIT
  \author{J.~H.~Kang}\affiliation{Yonsei University, Seoul} % Yonsei
% \author{J.~S.~Kang}\affiliation{Korea University, Seoul} % Korea
% \author{P.~Kapusta}\affiliation{H. Niewodniczanski Institute of Nuclear Physics, Krakow} % Krakow
% \author{M.~Kataoka}\affiliation{Nara Women's University, Nara} % Nara
% \author{S.~U.~Kataoka}\affiliation{Nara Women's University, Nara} % Nara
  \author{N.~Katayama}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
  \author{H.~Kawai}\affiliation{Chiba University, Chiba} % Chiba
% \author{H.~Kawai}\affiliation{Department of Physics, University of Tokyo, Tokyo} % Tokyo
% \author{Y.~Kawakami}\affiliation{Nagoya University, Nagoya} % Nagoya
% \author{N.~Kawamura}\affiliation{Aomori University, Aomori} % Aomori
  \author{T.~Kawasaki}\affiliation{Niigata University, Niigata} % Niigata
  \author{H.~Kichimi}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
  \author{H.~J.~Kim}\affiliation{Yonsei University, Seoul} % Yonsei
% \author{H.~O.~Kim}\affiliation{Sungkyunkwan University, Suwon} % Sungkyunkwan
  \author{Hyunwoo~Kim}\affiliation{Korea University, Seoul} % Korea
  \author{J.~H.~Kim}\affiliation{Sungkyunkwan University, Suwon} % Sungkyunkwan
  \author{S.~K.~Kim}\affiliation{Seoul National University, Seoul} % Seoul
% \author{T.~H.~Kim}\affiliation{Yonsei University, Seoul} % Yonsei
  \author{K.~Kinoshita}\affiliation{University of Cincinnati, Cincinnati, Ohio 45221} % Cincinnati
% \author{S.~Kobayashi}\affiliation{Saga University, Saga} % Saga
% \author{S.~Koishi}\affiliation{Tokyo Institute of Technology, Tokyo} % TIT
  \author{P.~Koppenburg}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
% \author{K.~Korotushenko}\affiliation{Princeton University, Princeton, New Jersey 08545} % Princeton
  \author{S.~Korpar}\affiliation{University of Maribor, Maribor}\affiliation{J. Stefan Institute, Ljubljana} % Ljubljana
  \author{P.~Kri\v zan}\affiliation{University of Ljubljana, Ljubljana}\affiliation{J. Stefan Institute, Ljubljana} % Ljubljana
  \author{P.~Krokovny}\affiliation{Budker Institute of Nuclear Physics, Novosibirsk} % BINP
% \author{R.~Kulasiri}\affiliation{University of Cincinnati, Cincinnati, Ohio 45221} % Cincinnati
% \author{S.~Kumar}\affiliation{Panjab University, Chandigarh} % Panjab
% \author{E.~Kurihara}\affiliation{Chiba University, Chiba} % Chiba
  \author{A.~Kuzmin}\affiliation{Budker Institute of Nuclear Physics, Novosibirsk} % BINP
  \author{Y.-J.~Kwon}\affiliation{Yonsei University, Seoul} % Yonsei
  \author{J.~S.~Lange}\affiliation{University of Frankfurt, Frankfurt}\affiliation{RIKEN BNL Research Center, Upton, New York 11973} % Frankfurt
% \author{G.~Leder}\affiliation{Institute of High Energy Physics, Vienna} % Vienna
  \author{S.~H.~Lee}\affiliation{Seoul National University, Seoul} % Seoul
  \author{T.~Lesiak}\affiliation{H. Niewodniczanski Institute of Nuclear Physics, Krakow} % Krakow
% \author{J.~Li}\affiliation{University of Science and Technology of China, Hefei} % USTC
  \author{A.~Limosani}\affiliation{University of Melbourne, Victoria} % Melbourne
  \author{S.-W.~Lin}\affiliation{Department of Physics, National Taiwan University, Taipei} % Taiwan
% \author{D.~Liventsev}\affiliation{Institute for Theoretical and Experimental Physics, Moscow} % ITEP
  \author{J.~MacNaughton}\affiliation{Institute of High Energy Physics, Vienna} % Vienna
  \author{G.~Majumder}\affiliation{Tata Institute of Fundamental Research, Bombay} % Tata
  \author{F.~Mandl}\affiliation{Institute of High Energy Physics, Vienna} % Vienna
% \author{D.~Marlow}\affiliation{Princeton University, Princeton, New Jersey 08545} % Princeton
% \author{T.~Matsuishi}\affiliation{Nagoya University, Nagoya} % Nagoya
% \author{H.~Matsumoto}\affiliation{Niigata University, Niigata} % Niigata
% \author{S.~Matsumoto}\affiliation{Chuo University, Tokyo} % Chuo
  \author{T.~Matsumoto}\affiliation{Tokyo Metropolitan University, Tokyo} % TMU
% \author{A.~Matyja}\affiliation{H. Niewodniczanski Institute of Nuclear Physics, Krakow} % Krakow
% \author{Y.~Mikami}\affiliation{Tohoku University, Sendai} % Tohoku
  \author{W.~Mitaroff}\affiliation{Institute of High Energy Physics, Vienna} % Vienna
% \author{K.~Miyabayashi}\affiliation{Nara Women's University, Nara} % Nara
% \author{Y.~Miyabayashi}\affiliation{Nagoya University, Nagoya} % Nagoya
  \author{H.~Miyake}\affiliation{Osaka University, Osaka} % Osaka
  \author{H.~Miyata}\affiliation{Niigata University, Niigata} % Niigata
% \author{L.~C.~Moffitt}\affiliation{University of Melbourne, Victoria} % Melbourne
% \author{D.~Mohapatra}\affiliation{Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061} % VPI
% \author{G.~R.~Moloney}\affiliation{University of Melbourne, Victoria} % Melbourne
% \author{G.~F.~Moorhead}\affiliation{University of Melbourne, Victoria} % Melbourne
% \author{T.~Mori}\affiliation{Tokyo Institute of Technology, Tokyo} % TIT
% \author{A.~Murakami}\affiliation{Saga University, Saga} % Saga
  \author{T.~Nagamine}\affiliation{Tohoku University, Sendai} % Tohoku
  \author{Y.~Nagasaka}\affiliation{Hiroshima Institute of Technology, Hiroshima} % Hiroshima
% \author{T.~Nakadaira}\affiliation{Department of Physics, University of Tokyo, Tokyo} % Tokyo
% \author{T.~Nakamura}\affiliation{Tokyo Institute of Technology, Tokyo} % TIT
  \author{E.~Nakano}\affiliation{Osaka City University, Osaka} % OsakaCity
% \author{M.~Nakao}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
% \author{H.~Nakazawa}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
% \author{Z.~Natkaniec}\affiliation{H. Niewodniczanski Institute of Nuclear Physics, Krakow} % Krakow
% \author{K.~Neichi}\affiliation{Tohoku Gakuin University, Tagajo} % TohokuGakuin
  \author{S.~Nishida}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
  \author{O.~Nitoh}\affiliation{Tokyo University of Agriculture and Technology, Tokyo} % TUAT
% \author{S.~Noguchi}\affiliation{Nara Women's University, Nara} % Nara
% \author{T.~Nozaki}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
% \author{A.~Ogawa}\affiliation{RIKEN BNL Research Center, Upton, New York 11973} % RIKEN
  \author{S.~Ogawa}\affiliation{Toho University, Funabashi} % Toho
% \author{F.~Ohno}\affiliation{Tokyo Institute of Technology, Tokyo} % TIT
  \author{T.~Ohshima}\affiliation{Nagoya University, Nagoya} % Nagoya
% \author{Y.~Ohshima}\affiliation{Tokyo Institute of Technology, Tokyo} % TIT
% \author{T.~Okabe}\affiliation{Nagoya University, Nagoya} % Nagoya
  \author{S.~Okuno}\affiliation{Kanagawa University, Yokohama} % Kanagawa
  \author{S.~L.~Olsen}\affiliation{University of Hawaii, Honolulu, Hawaii 96822} % Hawaii
% \author{Y.~Onuki}\affiliation{Niigata University, Niigata} % Niigata
  \author{W.~Ostrowicz}\affiliation{H. Niewodniczanski Institute of Nuclear Physics, Krakow} % Krakow
  \author{H.~Ozaki}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
  \author{P.~Pakhlov}\affiliation{Institute for Theoretical and Experimental Physics, Moscow} % ITEP
 \author{H.~Palka}\affiliation{H. Niewodniczanski Institute of Nuclear Physics, Krakow} % Krakow
  \author{C.~W.~Park}\affiliation{Korea University, Seoul} % Korea
  \author{H.~Park}\affiliation{Kyungpook National University, Taegu} % Kyungpook
% \author{K.~S.~Park}\affiliation{Sungkyunkwan University, Suwon} % Sungkyunkwan
  \author{N.~Parslow}\affiliation{University of Sydney, Sydney NSW} % Sydney
% \author{L.~S.~Peak}\affiliation{University of Sydney, Sydney NSW} % Sydney
% \author{M.~Pernicka}\affiliation{Institute of High Energy Physics, Vienna} % Vienna
% \author{J.-P.~Perroud}\affiliation{Institut de Physique des Hautes \'Energies, Universit\'e de Lausanne, Lausanne} % Lausanne
% \author{M.~Peters}\affiliation{University of Hawaii, Honolulu, Hawaii 96822} % Hawaii
  \author{L.~E.~Piilonen}\affiliation{Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061} % VPI
% \author{F.~J.~Ronga}\affiliation{Institut de Physique des Hautes \'Energies, Universit\'e de Lausanne, Lausanne} % Lausanne
% \author{N.~Root}\affiliation{Budker Institute of Nuclear Physics, Novosibirsk} % BINP
  \author{M.~Rozanska}\affiliation{H. Niewodniczanski Institute of Nuclear Physics, Krakow} % Krakow
  \author{H.~Sagawa}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
  \author{S.~Saitoh}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
  \author{Y.~Sakai}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
% \author{H.~Sakamoto}\affiliation{Kyoto University, Kyoto} % Kyoto
% \author{H.~Sakaue}\affiliation{Osaka City University, Osaka} % OsakaCity
  \author{T.~R.~Sarangi}\affiliation{Utkal University, Bhubaneswer} % Utkal
% \author{M.~Satapathy}\affiliation{Utkal University, Bhubaneswer} % Utkal
  \author{O.~Schneider}\affiliation{Institut de Physique des Hautes \'Energies, Universit\'e de Lausanne, Lausanne} % Lausanne
% \author{S.~Schrenk}\affiliation{University of Cincinnati, Cincinnati, Ohio 45221} % Cincinnati
% \author{J.~Sch\"umann}\affiliation{Department of Physics, National Taiwan University, Taipei} % Taiwan
% \author{C.~Schwanda}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba}\affiliation{Institute of High Energy Physics, Vienna} % KEK+Vienna
  \author{A.~J.~Schwartz}\affiliation{University of Cincinnati, Cincinnati, Ohio 45221} % Cincinnati
% \author{T.~Seki}\affiliation{Tokyo Metropolitan University, Tokyo} % TMU
  \author{S.~Semenov}\affiliation{Institute for Theoretical and Experimental Physics, Moscow} % ITEP
% \author{K.~Senyo}\affiliation{Nagoya University, Nagoya} % Nagoya
% \author{Y.~Settai}\affiliation{Chuo University, Tokyo} % Chuo
% \author{R.~Seuster}\affiliation{University of Hawaii, Honolulu, Hawaii 96822} % Hawaii
% \author{M.~E.~Sevior}\affiliation{University of Melbourne, Victoria} % Melbourne
% \author{T.~Shibata}\affiliation{Niigata University, Niigata} % Niigata
  \author{H.~Shibuya}\affiliation{Toho University, Funabashi} % Toho
% \author{B.~Shwartz}\affiliation{Budker Institute of Nuclear Physics, Novosibirsk} % BINP
  \author{V.~Sidorov}\affiliation{Budker Institute of Nuclear Physics, Novosibirsk} % BINP
% \author{V.~Siegle}\affiliation{RIKEN BNL Research Center, Upton, New York 11973} % RIKEN
  \author{J.~B.~Singh}\affiliation{Panjab University, Chandigarh} % Panjab
  \author{N.~Soni}\affiliation{Panjab University, Chandigarh} % Panjab
  \author{S.~Stani\v c}\altaffiliation[on leave from ]{Nova Gorica Polytechnic, Nova Gorica}\affiliation{University of Tsukuba, Tsukuba} % Tsukuba
  \author{M.~Stari\v c}\affiliation{J. Stefan Institute, Ljubljana} % Ljubljana
% \author{A.~Sugi}\affiliation{Nagoya University, Nagoya} % Nagoya
  \author{A.~Sugiyama}\affiliation{Saga University, Saga} % Saga
  \author{K.~Sumisawa}\affiliation{Osaka University, Osaka} % Osaka
  \author{T.~Sumiyoshi}\affiliation{Tokyo Metropolitan University, Tokyo} % TMU
% \author{K.~Suzuki}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
  \author{S.~Suzuki}\affiliation{Yokkaichi University, Yokkaichi} % Yokkaichi
  \author{S.~Y.~Suzuki}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
% \author{S.~K.~Swain}\affiliation{University of Hawaii, Honolulu, Hawaii 96822} % Hawaii
  \author{F.~Takasaki}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
% \author{B.~Takeshita}\affiliation{Osaka University, Osaka} % Osaka
  \author{K.~Tamai}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
% \author{Y.~Tamai}\affiliation{Osaka University, Osaka} % Osaka
  \author{N.~Tamura}\affiliation{Niigata University, Niigata} % Niigata
  \author{M.~Tanaka}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
% \author{G.~N.~Taylor}\affiliation{University of Melbourne, Victoria} % Melbourne
  \author{Y.~Teramoto}\affiliation{Osaka City University, Osaka} % OsakaCity
% \author{S.~Tokuda}\affiliation{Nagoya University, Nagoya} % Nagoya
% \author{M.~Tomoto}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
  \author{T.~Tomura}\affiliation{Department of Physics, University of Tokyo, Tokyo} % Tokyo
% \author{S.~N.~Tovey}\affiliation{University of Melbourne, Victoria} % Melbourne
% \author{K.~Trabelsi}\affiliation{University of Hawaii, Honolulu, Hawaii 96822} % Hawaii
  \author{T.~Tsuboyama}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
  \author{T.~Tsukamoto}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
  \author{S.~Uehara}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
% \author{K.~Ueno}\affiliation{Department of Physics, National Taiwan University, Taipei} % Taiwan
% \author{Y.~Unno}\affiliation{Chiba University, Chiba} % Chiba
  \author{S.~Uno}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
% \author{N.~Uozaki}\affiliation{Department of Physics, University of Tokyo, Tokyo} % Tokyo
% \author{Y.~Ushiroda}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
% \author{S.~E.~Vahsen}\affiliation{Princeton University, Princeton, New Jersey 08545} % Princeton
  \author{G.~Varner}\affiliation{University of Hawaii, Honolulu, Hawaii 96822} % Hawaii
  \author{K.~E.~Varvell}\affiliation{University of Sydney, Sydney NSW} % Sydney
% \author{C.~C.~Wang}\affiliation{Department of Physics, National Taiwan University, Taipei} % Taiwan
  \author{C.~H.~Wang}\affiliation{National Lien-Ho Institute of Technology, Miao Li} % Lien-Ho
  \author{J.~G.~Wang}\affiliation{Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061} % VPI
% \author{M.~Watanabe}\affiliation{Niigata University, Niigata} % Niigata
  \author{Y.~Watanabe}\affiliation{Tokyo Institute of Technology, Tokyo} % TIT
% \author{L.~Widhalm}\affiliation{Institute of High Energy Physics, Vienna} % Vienna
% \author{B.~D.~Yabsley}\affiliation{Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061} % VPI
  \author{Y.~Yamada}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
  \author{A.~Yamaguchi}\affiliation{Tohoku University, Sendai} % Tohoku
% \author{H.~Yamamoto}\affiliation{Tohoku University, Sendai} % Tohoku
% \author{T.~Yamanaka}\affiliation{Osaka University, Osaka} % Osaka
  \author{Y.~Yamashita}\affiliation{Nihon Dental College, Niigata} % NihonDental
% \author{Y.~Yamashita}\affiliation{Department of Physics, University of Tokyo, Tokyo} % Tokyo
  \author{M.~Yamauchi}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
  \author{H.~Yanai}\affiliation{Niigata University, Niigata} % Niigata
% \author{S.~Yanaka}\affiliation{Tokyo Institute of Technology, Tokyo} % TIT
% \author{Heyoung~Yang}\affiliation{Seoul National University, Seoul} % Seoul
% \author{J.~Yashima}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
% \author{P.~Yeh}\affiliation{Department of Physics, National Taiwan University, Taipei} % Taiwan
  \author{J.~Ying}\affiliation{Peking University, Beijing} % Peking
% \author{M.~Yokoyama}\affiliation{Department of Physics, University of Tokyo, Tokyo} % Tokyo
% \author{K.~Yoshida}\affiliation{Nagoya University, Nagoya} % Nagoya
  \author{Y.~Yuan}\affiliation{Institute of High Energy Physics, Chinese Academy of Sciences, Beijing} % IHEP
  \author{Y.~Yusa}\affiliation{Tohoku University, Sendai} % Tohoku
% \author{H.~Yuta}\affiliation{Aomori University, Aomori} % Aomori
% \author{S.~L.~Zang}\affiliation{Institute of High Energy Physics, Chinese Academy of Sciences, Beijing} % IHEP
  \author{C.~C.~Zhang}\affiliation{Institute of High Energy Physics, Chinese Academy of Sciences, Beijing} % IHEP
% \author{J.~Zhang}\affiliation{High Energy Accelerator Research Organization (KEK), Tsukuba} % KEK
  \author{Z.~P.~Zhang}\affiliation{University of Science and Technology of China, Hefei} % USTC
% \author{Y.~Zheng}\affiliation{University of Hawaii, Honolulu, Hawaii 96822} % Hawaii
  \author{V.~Zhilich}\affiliation{Budker Institute of Nuclear Physics, Novosibirsk} % BINP
% \author{Z.~M.~Zhu}\affiliation{Peking University, Beijing} % Peking
% \author{T.~Ziegler}\affiliation{Princeton University, Princeton, New Jersey 08545} % Princeton
  \author{D.~\v Zontar}\affiliation{University of Ljubljana, Ljubljana}\affiliation{J. Stefan Institute, Ljubljana} % Ljubljana
% \author{D.~Z\"urcher}\affiliation{Institut de Physique des Hautes \'Energies, Universit\'e de Lausanne, Lausanne} % Lausanne

\collaboration{The Belle Collaboration}



%\collaboration{Belle Collaboration}
%\noaffiliation

\begin{abstract}
We report the first observation of a $b\to u$ type charmless
baryonic $B$ decay, $\bp \to \pppi$, as well as $b\to s$ type $\bz
\to \ppkz$ and $\bp \to \ppkst$ decays. The analysis is based on a
78~fb$^{-1}$ data sample recorded on the $\Upsilon({\rm 4S})$
resonance with the Belle detector at KEKB.
%The branching fractions
We find ${\mathcal B}(\bp \to \pppi) = ( 3.06^{+0.73}_{-0.62} \pm
0.37) \times 10^{-6}$, ${\mathcal B}(B^0 \to \ppkz) =
(1.88^{+0.77}_{-0.60} \pm 0.23) \times 10^{-6}$, and ${\mathcal
B}(\bp \to \ppkst) = ( 10.3^{+3.6 + 1.3}_{-2.8 -1.7} ) \times
10^{-6}$. % for $m_{p\bar p < 2.85$ GeV.
We also update ${\mathcal B}(\bp \to \ppk) = (5.66^{+0.67}_{-0.57}
\pm 0.62 )\times 10^{-6}$, and present an upper limit on
${\mathcal B}(\bz \to \ppksz)$ at the 90\% confidence level.
%, ${\mathcal B}(\bz \to \ppksz) < 7.6 \times 10^{-6}$.
%
A common feature of the observed decay modes is threshold peaking in
baryon pair invariant mass.
%
\pacs{13.25.Hw, 13.60.Rj}
\end{abstract}
\maketitle
\tighten
{\renewcommand{\thefootnote}{\fnsymbol{footnote}}
\setcounter{footnote}{0}





The Belle Collaboration recently reported the observation of $\bp
\to \ppk$~\cite{ppk} and $\bz \to p\bar \Lambda\pi^-$~\cite{plpi}
decays. These are the first examples of $B$ meson decays to
charmless three-body final states containing baryons, and are
%dominated by 
candidates for  $b\to s$ penguin transitions. %diagrams
%
Our observation of these modes has stimulated much theoretical 
interest~\cite{CY,CHT,suzuki,newpa,glueball,rus,RosnerB} 
due to these decay 
channels may be used to 
test our theoretical understanding of
rare decay processes involving
baryons and search for
direct $CP$ violation.
One interesting feature of the observation is that 
the baryon pair mass 
spectra seem to peak toward threshold as originally conjectured 
by Refs.~\cite{HS,rhopn}. Lately more speculations on this are 
proposed~\cite{glueball,rus,RosnerB}. 
In this letter we report the first observation 
of $\bp \to \pppi$~\cite{conjugate}, which is dominated by the $b\to u$ tree
diagram. We also report the first observation of $\bz \to \ppkz$
and $\bp \to \ppkst$ decays, and improve the measurement of $\bp
\to \ppk$. A search for the $\bz \to \ppksz$ mode yields only an
upper limit.
With these new results we study the $\pp$ mass spectra to see 
if the threshold peaking observed in our previous results is confirmed 
with the newly observed modes.

%By comparing the rates in different $p\bar{p} K$ modes, we can 
%check for isospin invariance in baryonic $b\to s$ decays.
%

We use a  78 fb$^{-1}$  data sample,
consisting of $85.0 \pm 0.5$ million $B\bar{B}$ pairs,
collected by the Belle detector %on the $\Upsilon({\rm 4S})$ resonance
at the KEKB asymmetric energy $e^+e^-$ (3.5 on 8~GeV) collider~\cite{KEKB}.
The Belle detector is a large solid angle magnetic spectrometer
that consists of a three layer silicon vertex detector (SVD), a 50
layer central drift chamber (CDC), an array of aerogel threshold
\v{C}erenkov counters (ACC), a barrel-like arrangement of time of
flight scintillation counters (TOF), and an electromagnetic
calorimeter comprised of CsI (Tl) crystals located inside a
superconducting solenoid coil that provides a 1.5~T magnetic
field.  An iron flux return located outside of the coil is
instrumented to detect $K_L^0$ mesons and to identify muons. The
detector is described in detail elsewhere~\cite{Belle}.



The event selection criteria are based on the information obtained
from the tracking system
(SVD+CDC) and the hadron identification system (CDC+ACC+TOF),
and are optimized using Monte Carlo (MC)
simulated event samples.
All primary charged tracks
are required to satisfy track quality criteria
based on the track impact parameters relative to the
interaction point (IP). %, which is determined run-by-run.
The deviations from the IP position are required to be within
$\pm$1 cm in the transverse ($x$--$y$) plane, and within $\pm$3 cm
in the $z$ direction, where the $z$ axis is defined by the
positron beam line. Proton, kaon and pion candidates are selected 
%based on
using $p/K/\pi$ likelihood functions obtained from the hadron
identification system. For protons, we require $L_p/(L_p+L_K)> 0.6 $ and
$L_p/(L_p+L_{\pi})> 0.6$, where $L_{p/K/\pi}$ stands for the
proton/kaon/pion likelihood.
%The proton selection efficiency is about 84\% (88\% p and 80\% anti-p)
%for particles with
%momenta at 2 GeV/$c$,
%and the fate rate is about
%10\% for kaons and 3\% for pions.
%To identify charged kaons (pions), we require the kaon (pion)
%$K$--$\pi$ likelihood ratio to be greater than 0.6. 
We require $L_K/(L_K+L_{\pi})> 0.6$ to identify kaons and  
$L_{\pi}/(L_K+L_{\pi})> 0.6$ for pions.
$\ks$
candidates are reconstructed via the $\pi^+\pi^-$ decay channel
and have an invariant mass with  $ |M_{\pi^+\pi^-} - M_{K^0}| < 30$ MeV/$c^2$.
The candidate must have a displaced vertex and flight direction consistent with
a $\ks$ originating from the interaction point. 
%with the method described in Ref.~\cite{kpi}.  
%Note that only 
%kinematical information is used for the $\ks$ selection and there is no
%likelihood requirement on the
%secondary pions. 
We use the selected kaons and pions to form $\kst$
($\to \ks\pi^+$) and  $\ksz$ ($\to K^+\pi^-$) candidates by requiring the
invariant mass of the combination to be within 80 MeV/$c^2$ of the
$K^*$ mass. The numbers used are 892 MeV/$c^2$ and
896 MeV/$c^2$ for $M_{\kst}$ and $M_{\ksz}$, respectively.
%$\kst$ and $\ksz$ are selected by the $\ks\pi^+$ and $K^+\pi^-$ decay
%channels with a mass window 80 MeV/$c^2$ cut around the $\kst$ and
%$\ksz$~\cite{PDG} nominal masses.
%The same criteria are applied to the secondary charged kaons and
%pions, and $\ks$ from $K^*$ decays. 
To ensure the decay process is
genuinely charmless, we apply the charm veto. 
The regions  $2.85<M_{p \bar{p}}<3.128$ GeV/$c^2$
and $3.315<M_{p \bar{p}}<3.735$ GeV/$c^2$ are excluded to remove background 
from modes with $\eta_c, J/\psi$ and 
$\psi^{\prime},\chi_{c0},\chi_{c1}$ mesons, respectively.
The region  $2.262<M_{p \ks}<2.310$ GeV/$c^2$
is excluded to remove $\Lambda_c$ candidates.
%Ref.~\cite{ppk} to remove $\eta_c$, $J/\psi$, $\psi(2S)$, $\chi_c$
%and $\Lambda_c$.
%Generic $B$ meson decays occur mainly via the $b \to c$ transition, which
%normally have  more final-state particles than those for the rare decay modes
%reported here.
%As a result,


Since the initial collision 
center of mass energy is set to match the $\Upsilon({\rm
4S})$ resonance, which decays into a $B\bar{B}$ pair, one can use
the following two kinematic variables to identify the
reconstructed $B$ meson candidates: the beam
constrained mass $\mb = \sqrt{E^2_{\rm beam}-p^2_B}$, and the
energy difference $\de = E_B - E_{\rm beam}$, where $E_{\rm
beam}$, $p_B$, and $E_B$ are the beam energy, the momentum, and
energy of the reconstructed $B$ meson, respectively, in the rest frame of
the $\Upsilon({\rm 4S})$. The candidate region is
defined as 5.2 GeV/$c^2 < \mb < 5.29$ GeV/$c^2$ and $|\de|< 0.2$
GeV.


The dominant background arises from the continuum $e^+e^-
\to q\bar{q}$ process, 
with much smaller contributions from ``cross-feed'', where similar 
types of rare decay events pass each other's signal criteria.
%Except for a small 
%feed-across between these rare decay modes,
%the dominant background
%is from the continuum $e^+e^- \to q\bar{q}$ process.
The background from charm-bearing and charmless mesonic decays is 
negligible.
%This is confirmed using
%an off-resonance data set (8.8 fb$^{-1}$)
%taken 60 MeV
%below the $\Upsilon({\rm 4S})$ and a MC sample of 60 million continuum events.
In the $\Upsilon({\rm 4S})$ rest frame,
continuum events are jet-like while
$B\bar{B}$ events are more spherical. 
One can use the reconstructed momenta 
of final state particles to form various shape variables (e.g. thrust
angle, Fox-Wolfram moments, etc.) in order to categorize each event.  
We follow the scheme defined in Ref.~\cite{etapk} that
combines seven event shape variables into
a Fisher discriminant~\cite{fisher} in order to suppress
continuum background. The variables chosen have
almost no correlation
with $\mb$ and $\de$.
Probability density functions (PDFs) for the Fisher discriminant and
the cosine of the angle between the $B$ flight direction
and the beam direction in the $\Upsilon({\rm 4S})$ rest frame
are combined to form the signal (background)
likelihood ${\cal L}_{\rm S (BG)}$.
The signal PDFs are determined using signal MC
simulation; the background PDFs are obtained from the continuum MC
simulation for events with
5.27 GeV/$c^2 < \mb < $5.29 GeV/$c^2$
 and $|\de|< 0.1$ GeV.
We require
the likelihood ratio ${\cal LR} = {\cal L}_{\rm S}/({\cal L}_{\rm
S}+{\cal L}_{\rm BG})$ to be greater than 0.8, 0.9, 0.85, 0.8 and 0.8 for
$\ppk$, $\pppi$, $\ppks$, $\ppkst$ and $\ppksz$ modes, respectively.
The selection
points are determined by optimization of $S/\sqrt{(S+B)}$, where $S$ and $B$
denote the number of signal and background, respectively. Note that
a nominal signal branching fraction of $4 \times 10^{-6}$ is assumed.
%suppressing about 94\% of the background while retaining 66\% of the signal.

\begin{figure}[p]
%\vskip -2in
\centering 
%\epsfig{file=mergemb.eps,width=8cm,height=13cm}
%\epsfig{file=mergede.eps,width=8cm,height=13cm} \centering
%\epsfig{file=merge.eps,width=\textwidth,height=8cm}
%\hskip 1cm  
\epsfig{file=mergembppk.1.eps,width=5cm,height=4.3cm}
\hskip 1cm 
\epsfig{file=mergedeppk.1.eps,width=5cm,height=4.3cm} 
\hskip 1cm
\epsfig{file=mergembpppi.1.eps,width=5cm,height=4.3cm} 
\hskip 1cm 
\epsfig{file=mergedepppi.1.eps,width=5cm,height=4.3cm} 
\hskip 1cm 
\epsfig{file=mergembppks.1.eps,width=5cm,height=4.3cm} 
\hskip 1cm 
\epsfig{file=mergedeppks.1.eps,width=5cm,height=4.3cm} 
\hskip 1cm 
\epsfig{file=mergembppkst.1.eps,width=5cm,height=4.3cm} 
\hskip 1cm 
\epsfig{file=mergedeppkst.1.eps,width=5cm,height=4.3cm} 
\hskip 1cm 
%\epsfig{file=mergembppksz.1.eps,width=5cm,height=4.3cm} 
%\hskip 1cm 
%\epsfig{file=mergedeppksz.1.eps,width=5cm,height=4.3cm} 
\centering
\caption{ $\mb$ and $\de$ distributions for (a) $\ppk$, (b)
$\pppi$, (c) $\ppks$, and (d) $\ppkst$ % and (e) $\ppksz$ 
modes, for
$M_{p\bar p} < 2.85$ GeV/$c^2$. 
%The curves represent the fit
%results except in (e) where the
%curve is the 90\% confidence level signal yield superimposed 
%on the background fit.
}

\label{fg:mergembde}
\end{figure}



\begin{figure}[b!]
\centering
\mbox{\psfig{figure=ppk.phase.1.eps,width=2.5in}}
\mbox{\psfig{figure=pppi.phase.1.eps,width=2.5in}}
\mbox{\psfig{figure=ppks.phase.1.eps,width=2.5in}}
\mbox{\psfig{figure=ppkst.phase.1.eps,width=2.5in}}
\centering
\caption{Fitted signal yield divided by the bin size for
(a) $\ppk$, (b) $\pppi$, (c) $\ppks$, and (d) $\ppkst$ 
modes in bins of $\mpp$. The shaded distribution is from 
the phase-space MC simulation with area normalized to
signal yield.
%The insect shows the $p\bar{p}$ mass distribution for the 
%$J/\psi$ region.
}
\label{fg:allphase}
\end{figure}



%Since these decays do not follow three-body phase space decay,
%one can focus on
%the near threshold region.
Since the previous studies~\cite{ppk,plpi} showed an enhancement at
low baryon-antibaryon invariant mass, we first focus on the near
threshold region by 
requiring $\mpp < 2.85$ GeV/$c^2$ to make sure it
is below charmonium threshold.
The $\mb$ distributions (with $|\de|<$ 0.05
GeV), and the $\de$ distributions (with $\mb >$ 5.27 GeV/$c^2$)
for the $\ppk$, $\pppi$, $\ppks$, and $\ppkst$ %and $\ppksz$ 
modes are
shown in Fig.~\ref{fg:mergembde}. We use an unbinned likelihood fit
to estimate the signal yield:
%Events are fitted using the likelihood function:
$$ L = \prod_{i=1}^{N} [f_sP_s(M_{{\rm bc}_i},\Delta{E}_i)+
(1-f_s)P_b(M_{{\rm bc}_i},\Delta{E}_i)],$$
where $P_s(P_b)$ denotes the signal (background) PDF and $f_s$ is the signal
fraction of the total $N$ candidates.
%The PDFs
%are a Gaussian function to represent the signal $\mb$
%and a double Gaussian for $\de$ with parameters determined by
%MC simulation.
For the signal PDF,
we use a Gaussian in $\mb$ and a double Gaussian in $\de$.  We fix
the parameters of these functions to values determined by MC simulation.
Background shapes are studied using sideband
events: 0.1 GeV $ < |\de| < 0.2$ GeV for the $\mb$ study and
5.20 GeV/$c^2$ $ < \mb <$ 5.26 GeV/$c^2$ for $\de$.
These shapes are confirmed with a continuum MC sample.
We use the following parametrization first used by the ARGUS collaboration, 
$ f(\mb)\propto \mb\sqrt{1-x^2}
\exp[-\xi (1-x^2)]$,  
%background parametrization first used by the ARGUS collaboration~\cite{Argus} 
to model
the $\mb$ background, where $x$ is defined as $\mb/E_{\rm beam}$ and $\xi$ is
a parameter to be fit. 
The $\de$ background shape is modeled by a first order polynomial.
% and a first order polynomial 
%straight line 
%for the
%$\de$ background shape. 
There are possible cross-feeds from
$\ppkst$ and $\ppksz$ modes to $\ppk$, $\pppi$ and $\ppks$
modes; therefore the cross-feed region ($\de < -0.16$ GeV) 
is excluded in the fit.
Since the $\pppi$ mode can contain
non-negligible cross-feed events from the $\ppk$ mode, we include the
$\ppk$ MC cross-feed shape in the fit for the determination of the
$\pppi$ yield. 
%Events in the selected region are subjected to the
%following maximum likelihood function fit:
The fit results are shown in 
Fig.~\ref{fg:mergembde} by solid curves. 
%Since there is no clear evidence for the $\ppksz$
%mode, we plot the 90\% confidence level upper limit in this figure.
The fit yields are
96.4 $^{+11.2}_{-10.5}$,
37.4 $^{+8.1}_{-7.7}$,
11.3 $^{+4.1}_{-3.4}$,
and 14.5 $^{+4.6}_{-4.0}$
with
significances of $15.3$, $6.7$, $5.1$, and $6.0$ standard
deviations for
the $\ppk$, $\pppi$, $\ppks$, and $\ppkst$ modes, respectively. The 
significance is defined as $\sqrt{-2 {\rm ln}(L_0/L_{max})}$~\cite{PDG}, 
where $L_0$ and
$L_{max}$ denote the likelihood with signal yield fixed at
zero and at the fitted value, respectively. 
%by the maximum value of the likelihood function
%and the likelihood value with yield fixed at zero~\cite{PDG}.
%The yield for $\ppksz$ is less significant.
%The non-resonant $\ks \pi^+$ component of the 
%$\ppkst$ mode is included in the
%systematic error estimation as described later.



\begin{table}[b]
\caption{Branching fractions (in units of $10^{-6}$) 
in different $\mpp$ bins for the
$\ppk$, $\pppi$, $\ppks$ and $\ppkst$ modes.} \label{br}
\begin{center}
\begin{tabular}{ccccc}
$\mpp$ (GeV/$c^2$)&
$\ppk$&$\pppi$&$\ppks$&$\ppkst$
\\
\hline $1.876-2.0$&$0.91^{+0.23}_{-0.20}$ \ &
$0.29^{+0.15}_{-0.13}$ \ & $0.38^{+0.18}_{-0.14}$ \ & $1.40
^{+1.01}_{-0.74}$
\\
\hline $2.0-2.2$ \ & $1.33^{+0.31}_{-0.28}$ \ &
$0.57^{+0.23}_{-0.20}$ \ & $0.17^{+0.15}_{-0.10}$ \ & $2.11
^{+1.17}_{-0.90}$
\\
\hline $2.2-2.4$ \ &$1.20^{+0.29}_{-0.25}$ \ &
$0.39^{+0.19}_{-0.16}$ \ & $0.00^{+0.12}_{-0.12}$ \ & $1.01
^{+1.00}_{-0.65}$
\\
\hline $2.4-2.6$ \ & $0.82^{+0.25}_{-0.22}$ \ &
$0.46^{+0.21}_{-0.17}$ \ & $0.06^{+0.12}_{-0.06}$ \ & $0.64
^{+0.91}_{-0.56}$
\\
\hline $2.6-2.8$ \ & $0.51^{+0.21}_{-0.17}$ \ &
$0.05^{+0.12}_{-0.12}$ \ & $0.08^{+0.12}_{-0.06}$ \ & $0.95
^{+0.94}_{-0.60}$
\\
\hline $2.8-3.4$ \ & $0.53^{+0.22}_{-0.18}$ \ &
$0.00^{+0.04}_{-0.04}$ \ & $0.14^{+0.15}_{-0.10}$ \ & $1.19
^{+1.09}_{-0.71}$
\\
\hline $3.4-4.0$ \ & $0.15^{+0.15}_{-0.11}$ \ &
$0.15^{+0.16}_{-0.11}$ \ & $0.00^{+0.07}_{-0.07}$ \ & $2.07
^{+1.93}_{-1.28}$
\\
\hline $4.0-4.6$ \ & $0.00^{+0.08}_{-0.08}$ \ &
$0.15^{+0.21}_{-0.21}$ \ & $0.10^{+0.19}_{-0.10}$ \ & $0.93
^{+1.75}_{-1.75}$
\\
\hline $4.6-M_{p\bar{p}-{\rm lim}}$ \ & $0.20^{+0.17}_{-0.12}$ \ &
$1.00^{+0.54}_{-0.45}$ \ & $0.00^{+0.11}_{-0.11}$ \ & n/a
\\
%\hline total \ & $5.66^{+0.67}_{-0.57}$ \ & $3.06^{+0.73}_{-0.62}$
%\ & $0.94^{+0.38}_{-0.30}$ \ & $10.3^{+3.6}_{-2.8}$
%\\
\end{tabular}
\end{center}
\end{table}



%Since the decays are not uniform in phase space,
Although we do not have adequate statistics to perform a full Dalitz
plot analysis, the observed distribution is not uniform over phase
space. To reduce the model dependence
in determining the branching
fraction, we fit the signal yields separately 
%in $\de$ and $\mb$
%or determine upper limit yield
in nine bins of $\mpp$, and correct for the detection efficiencies
from MC simulation in each bin. In Fig.~\ref{fg:allphase}, we show
the signal yield versus $M_{p\bar p}$, with three-body phase space
from MC (normalized in area) superimposed. The observed mass
distributions all peak at low $p\bar{p}$ mass. The branching
fractions (${\cal B}$) in bins of $M_{p\bar{p}}$ for the
observed modes are given in Table~\ref{br}. 
The upper limit of the last bin is different for each mode and is 
equal to the kinematic limit, $M_{p\bar p-{\rm lim}}$.
%The exact width
%of the last bin is calculated for each decay mode due to 
%different meson masses. 
We sum the partial
branching fractions to obtain the total branching fractions.
The results are listed in Table~\ref{tab:tot} and
the  branching fractions below charmonium threshold, $M_{p\bar p} < 2.85$
GeV/$c^2$, are also listed for comparison. Note that 
${\cal B}(\bz \to \ppkz) = 2{\cal B}(\bz \to \ppks)$ is
assumed. 



The search for $\ppksz$ gives a yield of 13$^{+6}_{-5}$ events with
  a significance of about 3 standard deviations. 
% but this yield is
%  believed to include some non-resonant $K^+\pi^-$ contribution.
Since it is less significant, 
we use the fit results to estimate the expected background
and compare this  with the observed number of events
in the signal region
in order to set the upper limit on the
yield at the 90\% confidence level~\cite{Gary,Conrad}.
%The determined upper limit yield on top of the background
%is shown as solid line
%in Fig.~\ref{fg:mergembde}(e).
Note that the systematic uncertainty is needed in this estimation.
The upper limit yield of the $\ppksz$ mode in the full
$\mpp$ range is determined to
be 57 at the 90\% confidence level. The
branching fraction is found to be
${\cal B}(\bz \to \ppksz) < 7.6 \times 10^{-6}$.



\begin{table}[htb]
\caption{Branching fractions (in units of $10^{-6}$) 
in the full $\mpp$ range and below the 
charm threshold ($M_{p\bar p} < 2.85$GeV/$c^2$)
for the
$\ppk$, $\pppi$, $\ppks$ and $\ppkst$ modes. Statistical and systematic errors
are quoted.}
\label{tab:tot} 
\begin{center}
\begin{tabular}{ccc}
mode& full $\mpp$ range & $M_{p\bar p} < 2.85$GeV/$c^2$ \\
\hline
$\bp \to \ppk$& 
$5.66^{+0.67}_{-0.57} \pm 0.62 $&
$4.89^{+0.59}_{-0.55} \pm 0.54 $ \\
\hline
$\bp \to \pppi$&
$3.06^{+0.73}_{-0.62} \pm 0.37 $&
$1.76^{+0.42}_{-0.37} \pm 0.21 $ \\
\hline
$\bz \to \ppkz$&
$1.88^{+0.77}_{-0.60}  \pm 0.23 $&
$1.56^{+0.52}_{-0.49}  \pm 0.19 $ \\
\hline
$\bp \to \ppkst$&
$10.3^{+3.6 + 1.3}_{-2.8 - 1.7}$&
$6.7^{+2.4 + 0.9}_{-2.0 - 1.1} $
\\
\end{tabular}
\end{center}
\end{table}



\vskip 0.3cm
%\begin{eqnarray}
%{\cal B}(\bp \to \ppk) &=& (5.66\,^{+\,0.67}_{-\,0.57} \; ({\rm
%stat}) \pm 0.62 \; ({\rm syst})) \times 10^{-6}, \nonumber\\
%{\cal B}(\bp \to \pppi) &=& (3.06\,^{+\,0.73}_{-\,0.62} \; ({\rm
%stat}) \pm 0.37 \; ({\rm syst})) \times 10^{-6}, \nonumber\\
%{\cal B}(\bz \to \ppkz) &=& (1.88\,^{+\,0.77}_{-\,0.60} \; ({\rm
%stat}) \pm 0.23 \; ({\rm syst})) \times 10^{-6}, \nonumber\\
%{\cal B}(\bp \to \ppkst) &=& (10.3\,^{+\,3.6}_{-\,2.8} \; ({\rm
%stat}) \,^{+\,1.3}_{-\,1.7} \; ({\rm syst})) \times 10^{-6},
%\nonumber
%\end{eqnarray}
%where ${\cal B}(\bz \to \ppkz) = 2{\cal B}(\bz \to \ppks)$ is
%assumed, and
%$
%{\cal B}(\bz \to \ppksz) < 7.6 \times 10^{-6}.
%$
%For the region below charmonium threshold, $M_{p\bar p} < 2.85$
%GeV/$c^2$, the branching fractions are 
%\begin{eqnarray}
%{\cal B}(\bp \to \ppk) &=& (4.89^{+0.59}_{-0.55} \; ({\rm
%stat}) \pm 0.54 \; ({\rm syst})) \times 10^{-6}, \nonumber\\
%{\cal B}(\bp \to \pppi) &=& (1.76^{+0.42}_{-0.37} \; ({\rm
%stat}) \pm 0.21 \; ({\rm syst})) \times 10^{-6}, \nonumber\\
%{\cal B}(\bz \to \ppkz) &=& (1.56^{+0.52}_{-0.49} \; ({\rm
%stat}) \pm 0.19 \; ({\rm syst})) \times 10^{-6}, \nonumber\\
%{\cal B}(\bp \to \ppkst) &=& (6.70^{+2.36}_{-1.95} \; ({\rm
%stat}) \,^{+\,0.87}_{-\,1.07} \; ({\rm syst})) \times 10^{-6}.
%\nonumber
%\end{eqnarray}






Systematic uncertainties %in particle selection
are studied using high statistics control samples. For proton
identification, we use a  $\Lambda \to p \pi^-$ sample, while for
$K/\pi$ identification we use a $D^{*+} \to D^0\pi^+$,
 $D^0 \to K^-\pi^+$ sample.
%the $\cal LR$ selection is studied
%with a
%$B^0 \to D^- \pi^+$, $D^- \to \ks \pi^-$ sample
Tracking efficiency is studied with
fully and partially reconstructed $D^*$ samples.
%$\eta \to \gamma\gamma$ and $\eta \to \pi^+\pi^-\pi^0$ samples.
$\ks$ reconstruction efficiency is studied with a $D^- \to \ks\pi^-$
sample.
The $\cal LR$ continuum suppression uncertainty is studied with 
%a $B \to D^0\pi,D^0 \to K\pi$ control sample.
$\bp \to J/\psi K^+$, $\bz \to J/\psi\ks$, $\bp \to J/\psi\kst$, and
$\bz \to J/\psi\ksz$
(with $J/\psi \to \mu^+\mu^-$) control samples.
Based on these studies,
we assign a 1\% error for each track, 3\% for each proton identification,
2\% for each kaon/pion identification, 5\% for $\ks$ reconstruction
and 6\% for the $\cal LR$ selection.


The systematic uncertainty  in the fit yield is studied by varying
the parameters of the signal and background PDFs. We assign an
error of 5\% for the $\pppi$ mode and 4\% for the other modes. 
%The feed down effect from
%$\ppk$ to $\pppi$ makes the total fit error of the $\pppi$ mode at
%the 5\% level. 
There is a  possibility of non-resonant $\ks \pi^+$
combinations passing our $\kst$ cut.  We study this by fitting for the $B$
yield in bins of $M_{\ks\pi^+}$.
%as shown in Fig.~\ref{fg:bw}. If we choose
Choosing a Breit--Wigner signal and a first order polynomial
background to estimate the $\bp \to \ppkst$ branching fraction,
the number drops by 9\%. 
We include this uncertainty in the estimation
of signal yield for the $\ppkst$ mode. The MC statistical
uncertainty and modeling with nine $\mpp$ bins contributes a 2\%
error in the branching fraction determination. The error on the
number
of $B\bar{B}$ pairs is determined to be 1\%, where an
assumption is made that the branching fractions of $\Upsilon({\rm 4S})$ 
to neutral and charged $B\bar{B}$ pairs are equal. 
%~\cite{Bellenote}

%\begin{figure}
%\centering \mbox{\psfig{figure=kst.eps,width=11cm,height=10cm}}
%\centering \caption{Fitted B yields vs.  $M_{\ks\pi^+}$. The
%selected mass range of $\kst$ is between 0.86GeV/$c^2$ and
%0.94GeV/$c^2$. The fit curve represents the Breit--Wigner signal
%and a first order polynomial background.} \label{fg:bw}
%\end{figure}



We first sum the correlated errors linearly (e.g., total 5\%
tracking error for the $\ppkst$ mode) and then combine with the
uncorrelated ones in quadrature. The determined systematic
uncertainties are 11\%, 12\%, 12\%, $^{+13}_{-16}$\%, and 13\% for
the $\ppk$, $\pppi$, $\ppkz$, $\ppkst$, and $\ppksz$ modes,
respectively.




Using the charm veto events, we perform a cross-check of our
analysis.  We determine $B \to J/\psi K^{(*)}$ branching fractions
by following the
same analysis procedure with $3.07$ GeV/$c^2 < \mpp < 3.11$ GeV/$c^2$
and using ${\mathcal B}(J/\psi \to \pp) = ( 2.12 \pm 0.10 \times 10^{-3})$
~\cite{PDG}. The obtained branching fractions
are ${\mathcal B}(\bp \to J/\psi K^+) = ( 1.17^{+0.12}_{-0.13} \pm 0.16)
\times 10^{-3}$,
${\mathcal B}(B^0 \to J/\psi K^0)
= ( 1.16^{+0.24}_{-0.24} \pm 0.16)
\times 10^{-3}$,
${\mathcal B}(\bp \to J/\psi \kst) = ( 1.08^{+0.51}_{-0.42} \pm 0.17)
\times 10^{-3}$, and
${\mathcal B}(\bz \to J/\psi \ksz) = ( 1.40^{+0.27}_{-0.26} \pm 0.21)
\times 10^{-3}$,
which are in agreement with the world average values~\cite{PDG}.



%Our observation~\cite{ppk,plpi} of $\bp\to p\bar{p}K^+$ and $\bz
%\to \plpi$ modes have stimulated much theoretical
%interest~\cite{CY,CHT,suzuki,newpa,Rosner}. 
The present results, shown in Table~\ref{tab:tot},
offer valuable information for understanding the mechanism of charmless
baryonic $B$ decay. In particular, the threshold peaking
behavior is
now firmly established. 
%Note that the $M_{p\bar p}$ spectrum
%for $\bp \to \pppi$ seems to extend farther beyond threshold. This
%may be correlated with the strength observed in $\bz
%\to \plpi$ mode~\cite{newpa}. 
The $\bp \to \ppk$ data can be used to constrain the production of narrow
glueball states that decay to $\pp$~\cite{glueball}. With the current
statistics, we can not set a very stringent bound.
%On the other hand, it is still too early to state
%whether a narrow glueball state in $M_{p\bar p}$
%spectrum~\cite{glueball} of $\bp\to p\bar{p}K^+$ at the $1 \times
%10^{-6}$ level is ruled out.
%
It should be noted that the observed $\bp\to\pppi$ rate is less
than $\bp\to\ppk$, which is consistent with what is observed in
$B\to K\pi$, $\pi\pi$ modes. The $\bz\to p\bar pK^0$ rate is
considerably lower than that of the $\bp\to\ppk$ mode
%, indicating that
%$p\bar p$ may have more than one isospin component, 
which should be contrasted with $B^{0,+}\to \pi^0 K^{0,+}$ modes
and also $B^{0,+}\to J/\psi K^{0,+}$ modes . 
This indicates that the intermediate $p\bar p$ system is nontrivial.
%
These modes are of interest for direct $CP$ violation searches. For
the $B^\mp \to p\bar pK^\mp$ and $p\bar p\pi^\mp$ modes that have
larger statistics, we define the charge asymmetry  
as $(N_{B^-} - N_{B^+})/ (N_{B^-} + N_{B^+})$ and find the values are 
%$$A_{cp} = {{{\mathcal B} (B^- \to \pp h^-) - {\mathcal B} (B^+ \to \pp h^+)}
%\over {{\mathcal B} (B^- \to \pp h^-) + {\mathcal B} (B^+ \to \pp h^+)}}.$$
%The measured values are
$-0.05 \pm 0.11 \pm 0.01$ and  
$-0.16\pm0.22 \pm 0.01$ 
respectively.  
The systematic error is determined by checking the null asymmetry with 
a $B \to D (\to K \pi) \pi$ control sample. 
%The listed errors are statistical errors only
%and the measured asymmetries are
%consistent with zero.
The measured asymmetries are consistent with zero for their large statistical
uncertainties.

%A theoretical
%conjecture~\cite{glueball} tried to use a glue-ball resonance $\sim$ 2.3
%GeV/$c^2$ for the partial explanation of the $\mpp$ threshold
%peaking effect for the $\ppk$ mode. We use this data set to set
%${\cal B}(\bp \to {\rm glue-ball}\ K^+)\times {\cal B}({\rm
%glue-ball}\ \to \pp) < 0.9 \times 10^{-6}$ at the the 90\%
%confidence level, for a possible narrow glue-ball state with  mass
%in the 2.2 - 2.4 GeV/$c^2$ range. The theoretical prediction is
%around $1 \times 10^{-6}$ which can not be ruled out by our
%present measurement.

%Analogous to $B\to K\pi$, $\pi\pi$ modes, the $\bp \to \pppi$ rate
%is below that of $\bp \to \ppk$, indicating tree--penguin
%interference. The rate for $\bz \to \ppkz$ is quite different from
%that of $\bp \to \ppk$, suggesting a $\pp$ system with nontrivial
%isospin components.
%
%An interesting emerging feature is that the baryon pair mass
%spectra seem to peak towards threshold. All newly observed modes
%confirm this pattern previously observed for $\bp \to \ppk$ and
%$\bz \to p\bar \Lambda\pi^-$, which was conjectured beforehand by
%theory~\cite{HS,rhopn} for charmless baryonic $B$ decays.



%In summary, using $85.0 \pm 0.5$ million $B\bar{B}$ events, we
%have measured
%${\cal B}(\bp \to \pppi) =(3.06\,^{+\,0.73}_{-\,0.62}
%         \pm 0.37)  \times 10^{-6},$
%${\cal B}(B^0 \to \ppkz) =(1.88\,^{+\,1.06}_{-\,0.60}
%           \pm 0.23) \times 10^{-6},$
%${\cal B}(\bp \to \ppkst) =(10.31\,^{+\,3.62}_{-\,2.77}
%           \,^{+\,1.34}_{-\,1.65}) \times 10^{-6},$
%for the first time, and set the upper limit
%${\cal B}(B^0 \to \ppksz) < 7.6  \times 10^{-6}$, at the 90\%
%confidence level.
%We also update ${\cal B}(\bp \to \ppk)
%=(5.66\,^{+\,0.67}_{-\,0.57} \pm 0.62) \times 10^{-6}.$
%
%The $\bp \to \pppi$ mode is the first charmless $b\to u$
%transition to baryonic final state ever to be observed. Whether
%dominated by $b\to u$ or $b\to s$ transitions, $B$ decay to
%charmless baryonic final states exhibit threshold peaking behavior
%in the baryon pair mass.


%\section*{Acknowledgments}
We wish to thank the KEKB accelerator group for the excellent
operation of the KEKB accelerator.
We acknowledge support from the Ministry of Education,
Culture, Sports, Science, and Technology of Japan
and the Japan Society for the Promotion of Science;
the Australian Research Council
and the Australian Department of Education, Science and Training;
the National Science Foundation of China under contract No.~10175071;
the Department of Science and Technology of India;
the BK21 program of the Ministry of Education of Korea
and the CHEP SRC program of the Korea Science and Engineering Foundation;
the Polish State Committee for Scientific Research
under contract No.~2P03B 01324;
the Ministry of Science and Technology of the Russian Federation;
the Ministry of Education, Science and Sport of the Republic of Slovenia;
the National Science Council and the Ministry of Education of Taiwan;
and the U.S.\ Department of Energy.



\begin{thebibliography}{99}

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\bibitem{plpi}
M.Z.~Wang {\it et al.} (Belle Collaboration), 
Phys. Rev. Lett.{\bf 90}, 201802 (2003).



%\bibitem{CC}
%Throughout this report, %% whenever a mode is quoted
%the inclusion of the charge conjugate mode decay is implied
%unless otherwise stated.

%\bibitem{PP} F. Piccinini and  A.D. Polosa,
% Phys. Rev. D {\bf 65}, 097508 (2002);
% H.Y. Cheng and K.C. Yang, Phys. Lett. {\bf B533}, 271 (2002).
\bibitem{CY} H.Y. Cheng and K.C. Yang,
 Phys. Rev. D {\bf 66}, 014020 (2002).
\bibitem{CHT} C.K. Chua, W.S. Hou and S.Y. Tsai,
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\bibitem{suzuki} M. Suzuki, J. Phys. G {\bf 29}, B15 (2003). 
\bibitem{newpa} C.K. Chua and W.S. Hou, Eur. Phys. J. {\bf C29}, 27 (2003).
%\bibitem{Rosner} Z. Luo and J.L. Rosner, Phys. Rev. D {\bf 67}, 094017 (2003).
\bibitem{glueball}{
C.~K.~Chua, W.~S.~Hou and S.~Y.~Tsai,
Phys.\ Lett.\ B {\bf 544}, 139 (2002).}
\bibitem{rus} B.~Kirbikov, A.~Stavinsky, and V.~Fedotov, nucl-th/0310060.
\bibitem{RosnerB} J.L. Rosner, Phys. Rev. D {\bf 68}, 014004 (2003).

\bibitem{HS} W.S. Hou and A. Soni,
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\bibitem{rhopn} C.K. Chua, W.S. Hou and S.Y. Tsai,
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\bibitem{conjugate} {Throughout this report,
inclusion of charge conjugate mode is always implied unless
otherwise stated.}


\bibitem{KEKB}
S.~Kurokawa and E.~Kikutani {\it et al.},
Nucl. Instr. and Meth. A {\bf 499}, 1 (2003).
% E.~Kikutani ed., KEK Preprint 2001-157 (2001),
% to appear in Nucl. Instr. and Meth. A.

\bibitem{Belle}
A.~Abashian {\it et al.} (Belle Collaboration),
Nucl. Instr. and Meth. A {\bf 479}, 117 (2002).

%\bibitem{kpi}
%K.~Abe, {\it et al.}(Belle Collaboration),
%Phys. Rev. D {\bf 64}, 071101 (2001).

\bibitem{etapk}{
 K.~Abe {\it et al.} (Belle Collaboration), Phys. Lett. {\bf B517}, 309 (2001).
}

\bibitem{fisher}{
    R.A.~Fisher, Annals of Eugenics {\bf 7}, 179 (1936).
}

%\bibitem{Argus}{
%    H. Albrecht {\it et al.}, Phys. Lett. {\bf B241}, 278 (1990);
%        {\it ibid}. {\bf B254}, 288 (1991).
%}


\bibitem{PDG}
%D.E.~Groom {\it et al.} (Particle Data Group),
%Eur. Phys. J. {\bf C15}, 1 (2000).
K.~Hagiwara {\it et al.} (Particle Data Group), Phys. Rev. D {\bf
66}, 010001 (2002).


%\bibitem{Highland}
%R.D. Cousins and V.L. Highland, Nucl. Instr. and Meth. A {\bf
%320}, 331 (1993).

\bibitem{Gary} G.J. Feldman and R.D. Cousins, Phys. Rev. D {\bf 57},
 3873 (1998).

\bibitem{Conrad} J. Conrad {\it et al.},
Phys. Rev. D {\bf 67}, 012002 (2003).

\end{thebibliography}


\end{document}












hep-ex0310018.extracted_bib
\begin{thebibliography}{99}

\bibitem{ppk}
 K.~Abe {\it et al.} (Belle Collaboration),
 Phys. Rev. Lett. {\bf 88}, 181803 (2002).

\bibitem{plpi}
M.Z.~Wang {\it et al.} (Belle Collaboration), 
Phys. Rev. Lett.{\bf 90}, 201802 (2003).



%\bibitem{CC}
%Throughout this report, %% whenever a mode is quoted
%the inclusion of the charge conjugate mode decay is implied
%unless otherwise stated.

%\bibitem{PP} F. Piccinini and  A.D. Polosa,
% Phys. Rev. D {\bf 65}, 097508 (2002);
% H.Y. Cheng and K.C. Yang, Phys. Lett. {\bf B533}, 271 (2002).
\bibitem{CY} H.Y. Cheng and K.C. Yang,
 Phys. Rev. D {\bf 66}, 014020 (2002).
\bibitem{CHT} C.K. Chua, W.S. Hou and S.Y. Tsai,
 Phys. Rev. D {\bf 66}, 054004 (2002).
\bibitem{suzuki} M. Suzuki, J. Phys. G {\bf 29}, B15 (2003). 
\bibitem{newpa} C.K. Chua and W.S. Hou, Eur. Phys. J. {\bf C29}, 27 (2003).
%\bibitem{Rosner} Z. Luo and J.L. Rosner, Phys. Rev. D {\bf 67}, 094017 (2003).
\bibitem{glueball}{
C.~K.~Chua, W.~S.~Hou and S.~Y.~Tsai,
Phys.\ Lett.\ B {\bf 544}, 139 (2002).}
\bibitem{rus} B.~Kirbikov, A.~Stavinsky, and V.~Fedotov, nucl-th/0310060.
\bibitem{RosnerB} J.L. Rosner, Phys. Rev. D {\bf 68}, 014004 (2003).

\bibitem{HS} W.S. Hou and A. Soni,
 Phys. Rev. Lett. {\bf 86}, 4247 (2001).
\bibitem{rhopn} C.K. Chua, W.S. Hou and S.Y. Tsai,
 Phys. Lett. {\bf B528}, 233 (2002).




\bibitem{conjugate} {Throughout this report,
inclusion of charge conjugate mode is always implied unless
otherwise stated.}


\bibitem{KEKB}
S.~Kurokawa and E.~Kikutani {\it et al.},
Nucl. Instr. and Meth. A {\bf 499}, 1 (2003).
% E.~Kikutani ed., KEK Preprint 2001-157 (2001),
% to appear in Nucl. Instr. and Meth. A.

\bibitem{Belle}
A.~Abashian {\it et al.} (Belle Collaboration),
Nucl. Instr. and Meth. A {\bf 479}, 117 (2002).

%\bibitem{kpi}
%K.~Abe, {\it et al.}(Belle Collaboration),
%Phys. Rev. D {\bf 64}, 071101 (2001).

\bibitem{etapk}{
 K.~Abe {\it et al.} (Belle Collaboration), Phys. Lett. {\bf B517}, 309 (2001).
}

\bibitem{fisher}{
    R.A.~Fisher, Annals of Eugenics {\bf 7}, 179 (1936).
}

%\bibitem{Argus}{
%    H. Albrecht {\it et al.}, Phys. Lett. {\bf B241}, 278 (1990);
%        {\it ibid}. {\bf B254}, 288 (1991).
%}


\bibitem{PDG}
%D.E.~Groom {\it et al.} (Particle Data Group),
%Eur. Phys. J. {\bf C15}, 1 (2000).
K.~Hagiwara {\it et al.} (Particle Data Group), Phys. Rev. D {\bf
66}, 010001 (2002).


%\bibitem{Highland}
%R.D. Cousins and V.L. Highland, Nucl. Instr. and Meth. A {\bf
%320}, 331 (1993).

\bibitem{Gary} G.J. Feldman and R.D. Cousins, Phys. Rev. D {\bf 57},
 3873 (1998).

\bibitem{Conrad} J. Conrad {\it et al.},
Phys. Rev. D {\bf 67}, 012002 (2003).

\end{thebibliography}