Thu·Nov 17, 2022Thursday·November 17, 2022

1. 01*

   Measurement of the angle between jet axes in pp collisions at $\sqrt{s}=5.02$ TeV

   ALICE Collaboration

   This article reports measurements of the angle between differently defined jet axes in pp collisions at $\sqrt{s}=5.02$ TeV carried out by the ALICE Collaboration. Charged particles at midrapidity are clustered into jets with resolution parameters $R=0.2$ and 0.4. The jet axis, before and after Soft Drop grooming, is compared to the jet axis from the Winner-Takes-All (WTA) recombination scheme. The angle between these axes, $\Delta R_{\mathrm{axis}}$, probes a wide phase space of the jet formation and evolution, ranging from the initial high-momentum-transfer scattering to the hadronization process. The $\Delta R_{\mathrm{axis}}$ observable is presented for $20<p_{\mathrm{T}}^{\mathrm{ch}\mathrm{jet}}<100$ GeV/$c$, and compared to predictions from the PYTHIA 8 and Herwig 7 event generators. The distributions can also be calculated analytically with a leading hadronization correction related to the non-perturbative component of the Collins$-$Soper$-$Sterman (CSS) evolution kernel. Comparisons to analytical predictions at next-to-leading-logarithmic accuracy with leading hadronization correction implemented from experimental extractions of the CSS kernel in Drell$-$Yan measurements are presented. The analytical predictions describe the measured data within 20% in the perturbative regime, with surprising agreement in the non-perturbative regime as well. These results are compatible with the universality of the CSS kernel in the context of jet substructure.

   nucl-exhep-exJHEP(2023)·15 citations
2. 02*

   Production of ${\mathrm{K}}_{\mathrm{S}}^0$, $\Lambda$ ($\bar{\Lambda }$), ${\Xi }^{\pm }$ and ${\Omega }^{\pm }$ in jets and in the underlying event in pp and p$-$Pb collisions

   ALICE Collaboration

   The production of strange hadrons (K${}_{\mathrm{S}}^0$, $\Lambda$, ${\Xi }^{\pm }$, and ${\Omega }^{\pm }$), baryon-to-meson ratios ($\Lambda /{\mathrm{K}}_{\mathrm{S}}^0$, $\Xi /{\mathrm{K}}_{\mathrm{S}}^0$, and $\Omega /{\mathrm{K}}_{\mathrm{S}}^0$), and baryon-to-baryon ratios ($\Xi /\Lambda$, $\Omega /\Lambda$, and $\Omega /\Xi$) associated with jets and the underlying event were measured as a function of transverse momentum ($p_{\mathrm{T}}$) in pp collisions at $\sqrt{s}=13$ TeV and p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV with the ALICE detector at the LHC. The inclusive production of the same particle species and the corresponding ratios are also reported. The production of multi-strange hadrons, ${\Xi }^{\pm }$ and ${\Omega }^{\pm }$, and their associated particle ratios in jets and in the underlying event are measured for the first time. In both pp and p-Pb collisions, the baryon-to-meson and baryon-to-baryon yield ratios measured in jets differ from the inclusive particle production for low and intermediate hadron $p_{\mathrm{T}}$ (0.6$-$6 GeV/$c$). Ratios measured in the underlying event are in turn similar to those measured for inclusive particle production. In pp collisions, the particle production in jets is compared with PYTHIA 8 predictions with three colour-reconnection implementation modes. None of them fully reproduces the data in the measured hadron $p_{\mathrm{T}}$ region. The maximum deviation is observed for ${\Xi }^{\pm }$ and ${\Omega }^{\pm }$, which reaches a factor of about six. In p-Pb collisions, there is no significant event-multiplicity dependence for particle production in jets, in contrast to what is observed in the underlying event. The presented measurements provide novel constraints on hadronisation and its Monte Carlo description. In particular, they demonstrate that the fragmentation of jets alone is insufficient to describe the strange and multi-strange particle production in hadronic collisions at LHC energies.

   nucl-exhep-exJHEP(2023)·18 citations
3. 03*

   Two-particle transverse momentum correlations in pp and p-Pb collisions at energies available at the CERN Large Hadron Collider

   ALICE Collaboration

   Two-particle transverse momentum differential correlators, recently measured in Pb--Pb collisions at energies available at the CERN Large Hadron Collider (LHC), provide an additional tool to gain insights into particle production mechanisms and infer transport properties, such as the ratio of shear viscosity to entropy density, of the medium created in Pb-Pb collisions. The longitudinal long-range correlations and the large azimuthal anisotropy measured at low transverse momenta in small collision systems, namely pp and p-Pb, at LHC energies resemble manifestations of collective behaviour. This suggests that locally equilibrated matter may be produced in these small collision systems, similar to what is observed in Pb-Pb collisions. In this work, the same two-particle transverse momentum differential correlators are exploited in pp and p-Pb collisions at $\sqrt{s}=7$ TeV and $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV, respectively, to seek evidence for viscous effects. Specifically, the strength and shape of the correlators are studied as a function of the produced particle multiplicity to identify evidence for longitudinal broadening that might reveal the presence of viscous effects in these smaller systems. The measured correlators and their evolution from pp and p--Pb to Pb--Pb collisions are additionally compared to predictions from Monte Carlo event generators, and the potential presence of viscous effects is discussed.

   nucl-exhep-exPRC(2023)·11 citations
4. 04*

   Snowmass Neutrino Frontier Report

   Patrick Huber🇺🇸 · Kate Scholberg🇺🇸 · Elizabeth Worcester🇺🇸 · Jonathan Asaadi🇺🇸 · A. Baha Balantekin🇺🇸 · Nathaniel Bowden🇺🇸 · Pilar Coloma🇪🇸 · Peter B. Denton🇺🇸 · André de Gouvêa🇺🇸 · Laura Fields🇺🇸 · Megan Friend🇯🇵 · Steven Gardiner🇺🇸 and 47 other authors

   This report summarizes the current status of neutrino physics and the broad and exciting future prospects identified for the Neutrino Frontier as part of the 2021 Snowmass Process.

   ↳ hep-exastro-ph.COastro-ph.SRhep-ph+129 citations
5. 05*

   QCD under extreme conditions

   Peter Braun-Munzinger🇩🇪 · Anar Rustamov🇩🇪 · Johanna Stachel🇩🇪

   In nucleus-nucleus collisions at relativistic energies a new kind of matter is created, the Quark-Gluon Plasma (QGP). The phase diagram of such matter and the chemical freeze-out points will be presented in connection to the pseudo-critical temperature for the chiral cross over transition. The role of conserved charge fluctuations to give experimental access to the nature of the chiral phase transition will be summarized in terms of the relation to lattice QCD and the current experimental data. The QGP can be characterized as a nearly ideal liquid expanding hydrodynamically and the experimental data allow to extract transport parameters such as the bulk and shear viscosities. The energy loss of partons in the QGP probes the high parton density of the medium. The role of quarkonia and open charm hadrons as a probe of deconfinement and hadronization form the final topic.

   ↳ hep-phhep-exnucl-ex8 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.