Parton-transverse-momentum effects and the quantum-chromodynamic description of high-pTprocesses

Abstract

Previous calculations have shown that quantum chromodynamics can successfully describe the behavior of high-p, single-particle inclusive processes in the region fi k 50 GeV and pr 2 5 GeV/c. Here it is shown that this region can be enlarged significantly by including effects due to parton transverse momenta.

Systematic study of highpThadron spectra inpp,pA,Wang1 2000Phys. Rev. C2051210View full textAdd to dashboardCite

“…As pointed out by Owen and Kimel [28], in addition to the leading log contribution from initial-state radiation that is included in the Q 2 dependence of the parton distributions, the recoil effect of large-angle gluon emissions can lead to Q-dependent k 2 T N in this approach of QCD parton model. In the following we shall consider both a constant k 2 T N and one that depends on the momentum scale of the hard processes.…”

“…In this paper, we will adopt a more phenomenological approach by introducing initial parton transverse momentum with a Gaussian form of distribution as has been done in Drell-Yan [26], heavy quark [19], direct photon [20] and single inclusive hadron production [20,27,28]. Since it is difficult to extend the NLO calculation to p+A and A + A collisions where multiple collisions occur and our main purpose is to provide an effective description of single inclusive hadron spectra not only in p + p but also in p + A and A + A collisions, we will use lowest order (LO) parton model with a simple scheme of including the intrinsic transverse momentum with a Gaussian distribution.…”

“…In the following we shall consider both a constant k 2 T N and one that depends on the momentum scale of the hard processes. For the Q-dependent case, we choose the following form [28] in our model…”

Large-momentum-transfer production of direct photons, jets, and particles

“…Some useful references for general applications include those of Field, 1978;Ellis and Sachrajda, 1979;Reya, 1981;Owens, 1982b;and Pennington, 1983. The specific results needed for describing high-p r hadronic interactions have also been reviewed in the past.…”

“…In this theory the interactions of hadrons are described in terms of the interactions among the hadronic constituents-quarks and gluons (occasionally referred to collectively as partons). One of the key features of the theory that has set it apart from earlier field-theoretic descriptions of stronginteraction dynamics is the property of asymptotic freedom (Gross and Wilczek, 1973a;Politzer, 1973). This term is used to describe the weakening of the effective quark-gluon coupling at short distances or, equivalently, large momentum transfers.…”