Tue·May 18, 2021Tuesday·May 18, 2021

1. 01*

   Recent ALICE results on charm production and hadronisation

   Luuk Vermunt (for the ALICE Collaboration)🇳🇱

   Studies on the production of open charm hadrons are of paramount importance to investigate the charm-quark hadronisation mechanisms at the LHC, particularly through the evolution of the production ratio between different charm-hadron species. Measurements performed in pp and p--Pb collisions at the LHC have revealed unexpected features, qualitatively similar to what observed in larger systems and, in the charm sector, not in line with the expectations based on previous measurements from ${\mathrm{e}}^{+}{\mathrm{e}}^{-}$ colliders and in ep collisions. These results suggest that charm fragmentation fractions might not be universal and that the baryon-to-meson ratio depends on the collision system. Model calculations that better reproduce the ${\Lambda }_{\mathrm{c}}^{+}/{\mathrm{D}}^0$ ratio in pp collisions expect a significant contribution to ${\Lambda }_{\mathrm{c}}^{+}$ yield from decays of heavier charm-baryon states, rely on hadronisation via recombination mechanisms, or are based on new colour reconnection topologies. In this contribution, the most recent results on open heavy-flavour production in pp and Pb--Pb collisions measured by the ALICE Collaboration will be discussed. Emphasis will be given to the discussion of the impact of these studies on our understanding of the hadronisation processes.

   nucl-ex0 citations
2. 02*

   Measurements of ${}^{160}$Dy($p,\gamma$) at energies relevant for astrophysical $\gamma$ process

   Hao Cheng🇨🇳 · Bao-Hua Sun🇨🇳 · Li-Hua Zhu🇨🇳 · Motohiko Kusakabe🇨🇳 · Yun Zheng🇨🇳 · Liu-Chun He · Toshitaka Kajino🇯🇵 · Zhong-Ming Niu🇨🇳 · Tian-Xiao Li🇨🇳 · Cong-Bo Li🇨🇳 · Dong-Xi Wang🇨🇳 · Meng Wang🇨🇳 and 11 other authors

   Rare information on photodisintegration reactions of nuclei with mass numbers $A\approx 160$ at astrophysical conditions impedes our understanding of the origin of $p$-nuclei. Experimental determination of the key ($p,\gamma$) cross sections has been playing an important role to verify nuclear reaction models and to provide rates of relevant ($\gamma ,p$) reactions in $\gamma$-process. In this paper we report the first cross section measurements of ${}^{160}$Dy($p,\gamma$)${}^{161}$Ho and ${}^{161}$Dy($p,n$)${}^{161}$Ho in the beam energy range of 3.4 - 7.0 MeV, partially covering the Gamow window. Such determinations are possible by using two targets with various isotopic fractions. The cross section data can put a strong constraint on the nuclear level densities and gamma strength functions for $A\approx$ 160 in the Hauser-Feshbach statistical model. Furthermore, we find the best parameters for TALYS that reproduce the A $\sim$ 160 data available, ${}^{160}$Dy($p,\gamma$)${}^{161}$Ho and ${}^{162}$Er($p,\gamma$)${}^{163}$Tm, and recommend the constrained ${}^{161}$Ho($\gamma ,p$)${}^{160}$Dy reaction rates over a wide temperature range for $\gamma$-process network calculations. Although the determined ${}^{161}$Ho($\gamma$, p) stellar reaction rates at the temperature of 1 to 2 GK can differ by up to one order of magnitude from the NON-SMOKER predictions, it has a minor effect on the yields of ${}^{160}$Dy and accordingly the $p$-nuclei, ${}^{156,158}$Dy. A sensitivity study confirms that the cross section of ${}^{160}$Dy($p$, $\gamma$)${}^{161}$Ho is measured precisely enough to predict yields of $p$-nuclei in the $\gamma$-process.

   nucl-exastro-ph.SRnucl-thApJ(2021)·8 citations
3. 03*

   Flow harmonics in heavy ion physics at CMS and ATLAS

   Georgios Konstantinos Krintiras (on behalf of the CMS and ATLAS Collaborations)🇺🇸

   How can we gain a detailed insight into the hydrodynamic response of the system created in heavy ion collisions to the fluctuating initial geometry and viscous effects? Do we create a strongly interacting medium in proton-nucleus and proton-proton collisions, or rather a system of partons undergoing few scatterings? To what extent can we discriminate between initial momentum correlations and flow generated as a response to the initial geometry via interactions in the final state? Do measurements of identified particle flow confirm the observations from inclusive charged hadrons? An experimental overview of anisotropic flow measurements, ranging from large down to the smallest collision systems, is given in these proceedings.

   nucl-ex1 citation
4. 04*

   The drip lines of kaonic nuclei

   J. Guo🇨🇳 · D. H. Chen🇨🇳 · Xian-Rong Zhou🇨🇳 · Q. B. Chen🇩🇪 · H.-J. Schulze🇮🇹

   The effects of an additional $K^{-}$ meson on the neutron and proton drip lines are investigated within Skyrme-Hartree-Fock approach combined with a Skyrme-type kaon-nucleon interaction. While an extension of the proton drip line is observed due to the strongly attractive $K^{-}p$ interaction, contrasting effects (extension and reduction) on the neutron drip line of Be, O, and Ne isotopes are found. The origin of these differences is attributed to the behavior of the highest-occupied neutron single-particle levels near the neutron drip line.

   ↳ nucl-thnucl-ex0 citations
5. 05*

   Heavy quark potential in quark-gluon Plasma: Deep neural network meets lattice quantum chromodynamics

   Shuzhe Shi🇨🇦 · Kai Zhou🇩🇪 · Jiaxing Zhao🇨🇳 · Swagato Mukherjee🇺🇸 · Pengfei Zhuang🇨🇳

   Bottomonium states are key probes for experimental studies of the quark-gluon plasma (QGP) created in high-energy nuclear collisions. Theoretical models of bottomonium productions in high-energy nuclear collisions rely on the in-medium interactions between the bottom and antibottom quarks. The latter can be characterized by the temperature ($T$) dependent potential, with real ($V_R(T,r)$) and imaginary ($V_I(T,r)$) parts, as a function of the spatial separation ($r$). Recently, the masses and thermal widths of up to $3S$ and $2P$ bottomonium states in QGP were calculated using lattice quantum chromodynamics (LQCD). Starting from these LQCD results and through a novel application of deep neural network, here, we obtain $V_R(T,r)$ and $V_I(T,r)$ in a model-independent fashion. The temperature dependence of $V_R(T,r)$ was found to be very mild between $T\approx 0-334$~MeV. For $T=151-334$~MeV, $V_I(T,r)$ shows a rapid increase with $T$ and $r$, which is much larger than the perturbation-theory-based expectations.

   ↳ hep-phhep-latnucl-exnucl-thPRD(2022)·74 citations
6. 06*

   Azimuthal dependence of two-particle transverse momentum current correlations

   Niseem Magdy🇺🇸 · Sumit Basu🇸🇪 · Victor Gonzalez🇺🇸 · Ana Marin🇩🇪 · Olga Evdokimov🇺🇸 · Roy A. Lacey🇺🇸 · Claude Pruneau🇺🇸

   Two-particle transverse momentum correlation functions are a powerful technique for understanding the dynamics of relativistic heavy-ion collisions. Among these, the transverse momentum correlator $G_2\left(\Delta \eta ,\Delta \phi \right)$ is of particular interest for its potential sensitivity to the shear viscosity per unit of entropy density $\eta /s$ of the quark-gluon plasma formed in heavy-ion collisions. We use the UrQMD, AMPT, and EPOS models for Au--Au at $\sqrt{s_{\mathrm{NN}}}$ = 200~GeV and Pb--Pb at $\sqrt{s_{\mathrm{NN}}}$ = 2760~GeV to investigate the long range azimuthal dependence of $G_2\left(\Delta \eta ,\Delta \phi \right)$, and explore its utility to constrain $\eta /s$ based on charged particle correlations. We find that the three models yield quantitatively distinct transverse momentum Fourier harmonics coefficients $a_{\mathrm{n}}^{p_{\mathrm{T}}}$. We also observe these coefficients exhibit a significant dependence on $\eta /s$ in the context of the AMPT model. These observations suggest that exhaustive measurements of the dependence of $G_2\left(\Delta \phi \right)$ with collision energy, system size, collision centrality, in particular, offer the potential to distinguish between different theoretical models and their underlying assumptions. Exhaustive analyses of $G_2\left(\Delta \phi \right)$ obtained in large and small systems should also be instrumental in establishing new constraints for precise extraction of $\eta /s$.

   ↳ nucl-thhep-phnucl-exEPJC(2021)·3 citations
7. 07*

   QED radiative corrections for accelerator neutrinos

   Oleksandr Tomalak🇺🇸 · Qing Chen🇺🇸 · Richard J. Hill🇺🇸 · Kevin S. McFarland🇺🇸

   Neutrino oscillation experiments at accelerator energies aim to establish charge-parity violation in the neutrino sector by measuring the energy-dependent rate of ${\nu }_e$ appearance and ${\nu }_{\mu }$ disappearance in a ${\nu }_{\mu }$ beam. These experiments can precisely measure ${\nu }_{\mu }$ cross sections at near detectors, but ${\nu }_e$ cross sections are poorly constrained and require theoretical inputs. In particular, quantum electrodynamics radiative corrections are different for electrons and muons. These corrections are proportional to the small quantum electrodynamics coupling $\alpha \approx 1/137$; however, the large separation of scales between the neutrino energy and the proton mass ($\sim \mathrm{GeV}$), and the electron mass and soft-photon detection thresholds ($\sim \mathrm{MeV}$) introduces large logarithms in the perturbative expansion. The resulting flavor differences exceed the percent-level experimental precision and depend on nonperturbative hadronic structure. We establish a factorization theorem for exclusive charged-current (anti)neutrino scattering cross sections representing them as a product of two factors. The first factor is flavor universal; it depends on hadronic and nuclear structure and can be constrained by high-statistics ${\nu }_{\mu }$ data. The second factor is non-universal and contains logarithmic enhancements, but can be calculated exactly in perturbation theory. For charged-current elastic scattering, we demonstrate the cancellation of uncertainties in the predicted ratio of ${\nu }_e$ and ${\nu }_{\mu }$ cross sections. We point out the potential impact of non-collinear energetic photons and the distortion of the visible lepton spectra and provide precise predictions for inclusive observables.

   ↳ hep-phhep-exnucl-exnucl-thNature Commun.(2022)·45 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.