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Nuclear Theory·nucl-th

Monday·October 28, 2019

6 papers—2 primary·4 cross-listed

All6Primary2Cross-lists4
  1. 03

    TMD Soft Function from Large-Momentum Effective Theory

    Xiangdong Ji🇨🇳 · Yizhuang Liu🇨🇳 · Yu-Sheng Liu🇨🇳

    We study Euclidean formulations of the transverse-momentum-dependent (TMD) soft function, which is a cross section for soft gluon radiations involving color charges moving in two conjugate lightcone directions in quantum chromodynamics. We show it is related to a special form factor of a pair of color sources traveling with nearly-lightlike velocities, which can be matched to TMD physical observables in semi-inclusive deep-inelastic scattering and Drell-Yan process in the framework of large momentum effective theory. It can also be extracted by combining a large-momentum form factor of light meson and its leading TMD wave function. These formulations are useful for initiating nonperturbative calculations of this useful quantity.

    ↳ hep-phhep-exhep-latnucl-ex+1NPB(2020)·106 citations
  2. 04

    Jet angularities in photoproduction at the Electron-Ion Collider

    Elke-Caroline Aschenauer🇺🇸 · Kyle Lee🇺🇸 · B.S. Page🇺🇸 · Felix Ringer🇺🇸

    We consider the one-parameter family of jet substructure observables known as angularities using the specific case of inclusive jets arising from photoproduction events at an Electron-Ion Collider (EIC). We perform numerical calculations at next-to-leading logarithmic accuracy within perturbative QCD and compare our results to PYTHIA 6 predictions. Overall, we find good agreement and conclude that jet substructure observables are feasible at the EIC despite the relatively low jet transverse momentum and particle multiplicities. We investigate the size of subleading power corrections relevant at low energies within the Monte Carlo setup. In order to establish the validity of the Monte Carlo tune, we also perform comparisons to jet shape data at HERA. We further discuss detector requirements necessary for angularity measurements at an EIC, focusing on hadron calorimeter energy and spatial resolutions. Possible applications of precision jet substructure measurements at the EIC include the tuning of Monte Carlo event generators, the extraction of nonperturbative parameters and studies of cold nuclear matter effects.

    ↳ hep-phhep-exnucl-exnucl-thPRD(2020)·49 citations
  3. 05

    Identifying the nature of the QCD transition in relativistic collision of heavy nuclei with deep learning

    Yi-Lun Du🇩🇪 · Kai Zhou🇩🇪 · Jan Steinheimer🇩🇪 · Long-Gang Pang🇺🇸 · Anton Motornenko🇩🇪 · Hong-Shi Zong🇨🇳 · Xin-Nian Wang🇺🇸 · Horst Stöcker🇩🇪

    Using deep convolutional neural network (CNN), the nature of the QCD transition can be identified from the final-state pion spectra from hybrid model simulations of heavy-ion collisions that combines a viscous hydrodynamic model with a hadronic cascade "after-burner". Two different types of equations of state (EoS) of the medium are used in the hydrodynamic evolution. The resulting spectra in transverse momentum and azimuthal angle are used as the input data to train the neural network to distinguish different EoS. Different scenarios for the input data are studied and compared in a systematic way. A clear hierarchy is observed in the prediction accuracy when using the event-by-event, cascade-coarse-grained and event-fine-averaged spectra as input for the network, which are about 80%, 90% and 99%, respectively. A comparison with the prediction performance by deep neural network (DNN) with only the normalized pion transverse momentum spectra is also made. High-level features of pion spectra captured by a carefully-trained neural network were found to be able to distinguish the nature of the QCD transition even in a simulation scenario which is close to the experiments.

    ↳ hep-phnucl-thEPJC(2020)·74 citations
  4. 06

    Hadron-in-jet production at partonic threshold

    Tom Kaufmann🇩🇪 · Xiaohui Liu🇨🇳 · Asmita Mukherjee🇮🇳 · Felix Ringer🇺🇸 · Werner Vogelsang🇩🇪

    We consider the longitudinal momentum distribution of hadrons inside jets in proton-proton collisions. At partonic threshold large double logarithmic corrections arise which need to be resummed to all orders. We develop a factorization formalism within SCET that allows for the joint resummation of threshold and jet radius logarithms. We achieve next-to-leading logarithmic NLL accuracy by including non-global logarithms in the leading-color approximation. Overall, we find that the threshold resummation leads to a sizable enhancement of the cross section and a reduced QCD scale dependence, suggesting that the all-order resummation can be important for the reliable extraction of fragmentation functions in global analyses when jet substructure data is included.

    ↳ hep-phhep-exnucl-exnucl-thJHEP(2020)·12 citations

Affiliations

first authorsco-authorsvia INSPIRE