  Dijet anomaly reported by the CDF (Collider Detector at Fermilab)
collaboration in 1.96 TeV p-pbar collisions is investigated within the standard
model by considering effects of parton distribution functions on various
processes: W+dijet, Z+dijet, WW, ZW, and top production. Since the anomalous
peak exists in the dijet-mass region of 140 GeV with the p-pbar center-of-mass
energy sqrt{s}=1.96 TeV, a relevant momentum fraction x of partons is roughly
0.1. In this x region, recent HERMES semi-inclusive charged-lepton scattering
experiment indicated that the strange-quark distribution could be very
different from a conventional one, which has been used for many years, based on
opposite-sign dimuon measurements in neutrino-induced deep inelastic
scattering. We investigated effects of such variations in the strange-quark
distribution s(x) on the anomaly. We found that distributions of W+dijets and
other process are affected by the strange-quark modifications in wide
dijet-mass regions including the 140 GeV one. Since the CDF anomaly was
observed in the shoulder region of the dijet-mass distribution, a slight
modification of the distribution shape could explain at least partially the CDF
excess. Therefore, it is important to consider such effects within the standard
model for judging whether the CDF anomaly indicates new physics beyond the
standard model. We also show modification effects of the strange-quark
distribution in the LHC (Large Hadron Collider) kinematics, where cross
sections are sensitive to a smaller-x region of s(x).
