  Thermal photons radiated in heavy-ion collisions represent an important
signal for a recently discovered new state of matter, the deconfined
quark-gluon plasma. However, a clean identification of this signal requires
precise knowledge of the prompt photons produced simultaneously in hard
collisions of quarks and gluons, mostly through their fragmentation. In this
paper, we demonstrate that PHENIX data on photons produced in proton-proton
collisions with low transverse momenta allow to extract new information on this
fragmentation process. While existing data do not yet convincingly favor one
parameterization (BFG II) over the two other frequently used photon
fragmentation functions (BFG I and GRV NLO), the data sets recorded by PHENIX
and STAR at BNL RHIC in 2013 with tenfold higher statistics should allow for
such an analysis.
