Mon·Dec 20, 2021Monday·December 20, 2021

1. 01*

   Forward rapidity J/$\psi$ production as a function of charged-particle multiplicity in pp collisions at $\sqrt{s}=$ 5.02 and 13 TeV

   ALICE Collaboration

   The production of J/$\psi$ is measured as a function of charged-particle multiplicity at forward rapidity in proton$-$proton (pp) collisions at center-of-mass energies $\sqrt{s}=$ 5.02 and 13 TeV. The J/$\psi$ mesons are reconstructed via their decay into dimuons in the rapidity interval (2.5 $<y<$ 4.0), whereas the charged-particle multiplicity density ($\mathrm{d}{N}_{\mathrm{ch}}/\mathrm{d}\eta$) is measured at midrapidity $(|\eta |<1)$. The production rate as a function of multiplicity is reported as the ratio of the yield in a given multiplicity interval to the multiplicity-integrated one. This observable shows a linear increase with charged-particle multiplicity normalized to the corresponding average value for inelastic events ($\mathrm{d}{N}_{\mathrm{ch}}/\mathrm{d}\eta /⟨\mathrm{d}{N}_{\mathrm{ch}}/\mathrm{d}\eta ⟩$), at both the colliding energies. Measurements are compared with available ALICE results at midrapidity and theoretical model calculations. First measurement of the mean transverse momentum ($⟨p_{\mathrm{T}}⟩$) of J/$\psi$ in pp collisions exhibits an increasing trend as a function of $\mathrm{d}{N}_{\mathrm{ch}}/\mathrm{d}\eta /⟨\mathrm{d}{N}_{\mathrm{ch}}/\mathrm{d}\eta ⟩$ showing a saturation towards high charged-particle multiplicities.

   nucl-exhep-exJHEP(2022)·35 citations
2. 02*

   Neutral to charged kaon yield fluctuations in Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76TeV

   ALICE Collaboration

   We present the first measurement of event-by-event fluctuations in the kaon sector in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=$ 2.76 TeV with the ALICE detector at the LHC. The robust fluctuation correlator ${\nu }_{\mathrm{dyn}}$ is used to evaluate the magnitude of fluctuations of the relative yields of neutral and charged kaons, as well as the relative yields of charged kaons, as a function of collision centrality and selected kinematic ranges. While the correlator ${\nu }_{\mathrm{dyn}}[{\mathrm{K}}^{+},{\mathrm{K}}^{-}]$ exhibits a scaling approximately in inverse proportion of the charged particle multiplicity, ${\nu }_{\mathrm{dyn}}[{\mathrm{K}}_{\mathrm{S}}^0,{\mathrm{K}}^{\pm }]$ features a significant deviation from such scaling. Within uncertainties, the value of ${\nu }_{\mathrm{dyn}}[{\mathrm{K}}_{\mathrm{S}}^0,{\mathrm{K}}^{\pm }]$ is independent of the selected transverse momentum interval, while it exhibits a pseudorapidity dependence. The results are compared with HIJING, AMPT and EPOS-LHC predictions, and are further discussed in the context of the possible production of disoriented chiral condensates in central Pb-Pb collisions.

   nucl-exhep-exPLB(2022)·17 citations
3. 03*

   $K^{\ast }(892{)}^0$ meson production in inelastic $p+p$ interactions at 40 and 80 GeV/$c$ beam momenta measured by NA61/SHINE at the CERN SPS

   NA61/SHINE Collaboration: A. Acharya🇵🇱 · H. Adhikary🇵🇱 · K.K. Allison🇺🇸 · N. Amin🇩🇪 · E.V. Andronov🇷🇺 · T. Antićić🇭🇷 · I.-C. Arsene🇳🇴 · M. Baszczyk🇵🇱 · D. Battagia🇺🇸 · S. Bhosale🇵🇱 · A. Blondel🇫🇷 · M. Bogomilov🇧🇬 and 135 other authors

   Measurements of $K^{\ast }(892{)}^0$ resonance production via its $K^{+}{\pi }^{-}$ decay mode in inelastic $p+p$ collisions at beam momenta 40 and 80 GeV/$c$ ($\sqrt{s_{NN}}=8.8$ and 12.3 GeV) are presented. The data were recorded by the NA61/SHINE hadron spectrometer at the CERN Super Proton Synchrotron. The \textit{template} method was used to extract the $K^{\ast }(892{)}^0$ signal. Transverse momentum and rapidity spectra were obtained. The mean multiplicities of $K^{\ast }(892{)}^0$ mesons were found to be $(35.1\pm 1.3(\mathrm{stat})\pm 3.6(\mathrm{sys}))\cdot 10^{-3}$ at 40 GeV/$c$ and $(58.3\pm 1.9(\mathrm{stat})\pm 4.9(\mathrm{sys}))\cdot 10^{-3}$ at 80 GeV/$c$. The NA61/SHINE results are compared with the EPOS1.99 and Hadron Resonance Gas models as well as with world data. The transverse mass spectra of $K^{\ast }(892{)}^0$ mesons and other particles previously reported by NA61/SHINE were fitted within the Blast-Wave model. The transverse flow velocities are close to 0.1--0.2 of the speed of light and are significantly smaller than the ones determined in heavy nucleus-nucleus interactions at the same beam momenta.

   nucl-exhep-exEPJC(2022)·16 citations
4. 04*

   Concerning pion parton distributions

   Z.-F. Cui🇨🇳 · M. Ding🇩🇪 · J. M. Morgado🇪🇸 · K. Raya🇪🇸 · D. Binosi🇮🇹 · L. Chang🇨🇳 · J. Papavassiliou🇪🇸 · C. D. Roberts🇨🇳 · J. Rodríguez-Quintero🇪🇸 · S. M. Schmidt🇩🇪

   Analyses of the pion valence-quark distribution function (DF), $u^{\pi }(x;\zeta )$, which explicitly incorporate the behaviour of the pion wave function prescribed by quantum chromodynamics (QCD), predict $u^{\pi }(x\simeq 1;\zeta )\sim (1-x{)}^{\beta (\zeta )}$, $\beta (\zeta \gtrsim m_p)>2$, where $m_p$ is the proton mass. Nevertheless, more than forty years after the first experiment to collect data suitable for extracting the $x\simeq 1$ behaviour of $u^{\pi }$, the empirical status remains uncertain because some methods used to fit existing data return a result for $u^{\pi }$ that violates this constraint. Such disagreement entails one of the following conclusions: the analysis concerned is incomplete; not all data being considered are a true expression of qualities intrinsic to the pion; or QCD, as it is currently understood, is not the theory of strong interactions. New, precise data are necessary before a final conclusion is possible. In developing these positions, we exploit a single proposition, viz. there is an effective charge which defines an evolution scheme for parton DFs that is all-orders exact. This proposition has numerous corollaries, which can be used to test the character of any DF, whether fitted or calculated.

   ↳ hep-phhep-exhep-latnucl-ex+1EPJA(2022)·57 citations
5. 05*

   Thermal freeze-out parameters and pseudo-entropy from charged hadron spectra in high energy collisions

   Xu-Hong Zhang🇨🇳 · Ya-Qin Gao🇨🇳 · Fu-Hu Liu🇨🇳 · Khusniddin K. Olimov🇺🇿

   We collected the transverse momentum (mass) spectra of charged hadrons (${\pi }^{-}$, ${\pi }^{+}$, $K^{-}$, $K^{+}$, $\overline{p}$, and $p$) produced in collisions over a center-of-mass energy range from 2.70 to 200 GeV (per nucleon pair). The modified Tsallis--Pareto-type function (the TP-like function) with average transverse flow velocity is used to describe the contribution of participant or constituent quarks to transverse momentum of considered hadron. The experimental spectra of ${\pi }^{\mp }$ and $K^{\mp }$ (or $\overline{p}$ and $p$) are fitted by the convolution of two (or three) TP-like functions due to the fact that two (or three) constituent quarks are regarded as two (or three) energy resources in the formation of considered hadron. From the reasonable fits to the spectra, the thermal freeze-out parameters are extracted, and the pseudo-entropy is newly defined and extracted. Some parameters quickly change in the energy range of less than 7.7 GeV, and slowly change in the energy range of greater than 7.7 GeV, indicating the variation of collision mechanism at around 7.7 GeV.

   ↳ hep-phhep-exnucl-exnucl-thAdv.High Energy Phys.(2022)·8 citations
6. 06*

   Proposed Lunar Measurements of $r$-Process Radioisotopes to Distinguish Origin of Deep-sea 244Pu

   Xilu Wang🇨🇳 · Adam M. Clark🇺🇸 · John Ellis🇬🇧 · Adrienne F. Ertel🇺🇸 · Brian D. Fields🇺🇸 · Brian J. Fry🇺🇸 · Zhenghai Liu🇨🇳 · Jesse A. Miller🇺🇸 · Rebecca Surman🇺🇸

   244Pu has recently been discovered in deep-sea deposits spanning the past 10 Myr, a period that includes two 60Fe pulses from nearby supernovae. 244Pu is among the heaviest $r$-process products, and we consider whether it was created in the supernovae, which is disfavored by nucleosynthesis simulations, or in an earlier kilonova event that seeded 244Pu in the nearby interstellar medium that was subsequently swept up by the supernova debris. We discuss how these possibilities can be probed by measuring 244Pu and other $r$-process radioisotopes such as 129I and 182Hf, both in lunar regolith samples returned to Earth by missions such as Chang'e and Artemis, and in deep-sea deposits.

   ↳ astro-ph.HEhep-phnucl-exnucl-th+1Astrophysics(2023)·13 citations
7. 07*

   Incorporating the weak mixing angle dependence to reconcile the neutron skin measurement on 208Pb by PREX-II

   Mattia Atzori Corona🇮🇹 · Matteo Cadeddu🇮🇹 · Nicola Cargioli🇮🇹 · Paolo Finelli🇮🇹 · Matteo Vorabbi🇺🇸

   The only available electroweak measurement of the ${}^{208}\mathrm{Pb}$ neutron skin, $\Delta R_{\mathrm{np}}$, performed by the PREX-II Collaboration through polarized electron-lead scattering, shows a mild tension with respect to both the theoretical nuclear-model predictions and a host of measurements. However, the dependence on the weak mixing angle should be incorporated in the calculation, since its low-energy value is experimentally poorly known. We first repeat the PREX-II analysis confirming their measurement by fixing the weak mixing angle to its standard model value. Then, we show the explicit dependence of the PREX-II measurement on the weak mixing angle, obtaining that it is fully degenerate with the neutron skin. To break this degeneracy, we exploit the weak mixing angle measurement from atomic parity violation on lead, obtaining a slightly thinner neutron skin but with about doubled uncertainties, possibly easing the PREX tension. Relying on the theoretical prediction, $\Delta R_{\mathrm{np}}^{\mathrm{th}}\approx 0.13-0.19\mathrm{fm}$, and using it as a prior in the fit, we find a weak mixing angle value about $1.2\sigma$ smaller than the standard model prediction. Thus, we suggest a possible solution of the PREX-II tension by showing that, considering its underlying dependence on the weak mixing angle, the PREX-II neutron skin determination could be in agreement with the other available measurements and predictions if the weak mixing angle at the proper energy scale is smaller than the standard model prediction.

   ↳ hep-phnucl-exnucl-thPRC(2022)·20 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.