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Nuclear Theory·nucl-th

Thursday·January 14, 2016

7 papers—3 primary·4 cross-listed

All7Primary3Cross-lists4
  1. 04

    Direct photon production and jet energy-loss in small systems

    Chun Shen🇨🇦 · Chanwook Park🇨🇦 · Jean-François Paquet🇨🇦 · Gabriel S. Denicol🇨🇦 · Sangyong Jeon🇨🇦 · Charles Gale🇨🇦

    Two types of penetrating probes, direct photon and QCD jets, are investigated in the background of a small and rapidly expanding droplet of quark-gluon plasma. The additional thermal electromagnetic radiation results in a 50\% enhancement of the direct photons. In high multiplicity p+Pb collisions, jets can lose a sizeable fraction of their initial energy, leading to a charged hadron of 0.8 at a transverse momentum around 10\,GeV. Those two proposed measurements can help understand the apparent collective behaviour observed in small collision systems.

    ↳ hep-phnucl-exnucl-thNPA(2016)·16 citations
  2. 05

    Rapidity regulators in the semi-inclusive deep inelastic scattering and Drell-Yan processes

    Sean Fleming🇺🇸 · Ou Z. Labun🇺🇸

    We study the semi-inclusive limit of the deep inelastic scattering and Drell-Yan (DY) processes in soft collinear effective theory. In this regime so-called threshold logarithms must be resummed to render perturbation theory well behaved. Part of this resummation occurs via the Dokshitzer, Gribov, Lipatov, Altarelli, Parisi (DGLAP) equation, which at threshold contains a large logarithm that calls into question the convergence of the anomalous dimension. We demonstrate here that the problematic logarithm is related to rapidity divergences, and by introducing a rapidity regulator can be tamed. We show that resumming the rapidity logarithms allows us to reproduce the standard DGLAP running at threshold as long as a set of potentially large non-perturbative logarithms are absorbed into the definition of the parton distribution function (PDF). These terms could, in turn, explain the steep fall-off of the PDF in the endpoint. We then go on to show that the resummation of rapidity divergences does not change the standard threshold resummation in DY, nor do our results depend on the rapidity regulator we choose to use.

    ↳ hep-phnucl-thPRD(2017)·3 citations
  4. 07

    Short-distance RG-analysis of radiative decays

    D. A. S. Molnar🇧🇷 · R. F. Luiz🇧🇷 · R. Higa🇧🇷

    We present a renormalization-group analysis of the radiative decays into and . We assume a molecule for the long-distance structure and parametrize its short-distance physics as contact interactions. Using effective field theory techniques and power-divergence subtraction scheme, we find that short- and long-distance physics are equally important in these decays. Our calculations set a lower limit to the corresponding decay widths, which can in principle be tested experimentally. Our results may be used as guide to build models for the short-distance.

    ↳ hep-phnucl-th6 citations

Affiliations

first authorsco-authorsvia INSPIRE