Abstract
A detailed reanalysis of the single gluon emission rate at next-to-leading twist is carried out. As was the case in prior efforts, the problem is cast in the framework of deep-inelastic scattering (DIS) of an electron off a large nucleus. The quark produced in the interaction propagates through the remaining nucleus and engenders scattering and gluon radiation, which is calculated in the limit of one re-scattering. This medium induced single gluon emission rate forms the basis of several energy loss calculations in both DIS and heavy-ion collisions. Unlike prior efforts, a complete transverse momentum gradient expansion of the hadronic tensor, including $N_c$ suppressed terms, phase terms and finite gluon momentum fraction terms, ignored previously, is carried out. These terms turn out to be surprisingly large. In contrast to prior efforts, the full next-to-leading twist gluon emission kernel is found to be positive definite and slowly increasing with the exchanged transverse momentum. Phenomenological consequences of these new contributions are discussed.
Highlights
Jet modification in a quark gluon plasma (QGP) [1,2] is understood as a multiscale process [3–6]
Prior to the use of multistage event generators, there was more than 15 years of development of jet modification where the single gluon emission rate at next-to-leading twist has been used to study a variety of high transverse momentum observables [16,25–32]
Compared to the Guo and Wang (GW) result, our current calculation predicts a much smaller value of the medium modification kernel up to a length around 1.5τF. This is due to the negative contribution from the preemission rescattering diagram as given by Eq (52), which is absent in the GW work due to its neglect of the k⊥-dependent phase factors before collinear expansion
Summary
Jet modification in a quark gluon plasma (QGP) [1,2] is understood as a multiscale process [3–6]. Prior to the use of multistage event generators, there was more than 15 years of development of jet modification where the single gluon emission rate at next-to-leading twist has been used to study a variety of high transverse momentum (high-pT ) observables [16,25–32] If at least one scattering, either in the amplitude or the complex conjugate, happens before the emission, the contributions are expected to be suppressed by the momentum fraction of the gluon These diagrams were neglected in the limit of the soft gluon approximation.
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