Mon·Oct 28, 2019Monday·October 28, 2019

1. 01*

   Measurement of ${\Lambda }_{\mathrm{c}}^{+}$ baryons and ${\mathrm{D}}_{\mathrm{s}}^{+}$ mesons in Pb-Pb collisions with ALICE

   Luuk Vermunt (for the ALICE Collaboration)🇳🇱

   The study of heavy-flavour (charm and beauty) production is important to understand the properties of the Quark-Gluon Plasma (QGP) formed in ultra-relativistic heavy-ion collisions, since heavy quarks are produced in the initial stages of the collisions and subsequently interact with the medium throughout its evolution. In the QGP, strange quarks are expected to be abundantly produced and may recombine with charm quarks leading to an enhancement of the nuclear modification factor ($R_{\mathrm{AA}}$) of ${\mathrm{D}}_{\mathrm{s}}^{+}$ mesons compared to that of other charmed meson states at low and intermediate $p_{\mathrm{T}}$. The measurement of elliptic flow ($v_2$) of ${\mathrm{D}}_{\mathrm{s}}^{+}$ mesons is useful to determine the degree of thermalisation of charm quarks in the collective expansion of the QGP. In addition, charm quarks could recombine with light di-quark states in the medium, which would lead to an enhancement of the ${\Lambda }_{\mathrm{c}}^{+}/{\mathrm{D}}^0$ baryon-to-meson ratio as compared to that in pp collisions. Precise measurements of these particle species in Pb-Pb collisions, therefore, give a deeper insight into the hadronisation mechanisms that heavy quarks undergo in the strongly-interacting medium. In this contribution, the latest results measured with ALICE for ${\mathrm{D}}_{\mathrm{s}}^{+}$-meson and ${\Lambda }_{\mathrm{c}}^{+}$-baryon production in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV, using data from Run 2 of the LHC are discussed.

   nucl-exPoS(2020)·12 citations
2. 02*

   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
3. 03*

   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
4. 04*

   Constraining the Particle Production Mechanism in Au+Au Collisions at $\sqrt{s_{NN}}=$ 7.7, 27, and 200 GeV Using A Multi Phase Transport Model

   Abhirikshma Nandi🇮🇳 · Lokesh Kumar🇮🇳 · Natasha Sharma🇮🇳

   We study the production of pions, kaons, and (anti)protons in A Multi Phase Transport (AMPT) Model in Au+Au collisions at $\sqrt{s_{NN}}=$ 7.7, 27, and 200 GeV. We present the centrality and energy dependence of various bulk observables such as invariant yields as a function of transverse momentum $p_T$, particle yields $dN/dy$, average transverse momentum $⟨p_T⟩$, and various particle ratios, and compare them with experimental data. Both default and string melting (SM) versions of the AMPT model are used with three different sets of initial conditions. We observe that neither the default nor the SM version of the model could consistently describe the centrality dependence of all observables at the above energies with any one set of initial conditions. The energy dependence behavior of the experimental observables for 0--5\% central collisions is in general better described by the default AMPT model using the modified HIJING parameters for Lund string fragmentation and 3mb parton scattering cross-section. In addition, the kaon production as well as the $K/\pi$ ratio at 7.7 GeV are under predicted by the AMPT model.

   ↳ hep-phnucl-exPRC(2020)·17 citations
5. 05*

   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${}^{\prime }$ 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

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.