Thu·Sep 24, 2020Thursday·September 24, 2020

1. 01*

   Quarkonia production as a function of charged-particle multiplicity in pp collisions at $\sqrt{s}=13$ TeV with ALICE

   Yanchun Ding (for the ALICE Collaboration)🇨🇳

   In pp collisions at LHC energies, heavy quarks are produced in initial hard scatterings and then these quarks hadronize in either open heavy-flavor hadrons or quarkonia (e.g. J/$\psi$, $\psi (2S)$, ${\rm Y}$). The study of quarkonium production as a function of charged-particle multiplicity links soft and hard processes and allows one to study their interplay. While a linear increase of quarkonium production as a function of charged-particle multiplicity can be reasonably well understood in the context of multi-parton interactions, the observation of deviations with respect to a linear increase requires a more detailed description of the collision. In this contribution, we will present the latest ALICE measurements at forward rapidity for J/$\psi$ and ${\rm Y}$ production as a function of charged-particle multiplicity in pp collisions at $\sqrt{s}=13$ TeV. The first measurement of the double ratios of relative yield of ${\rm Y}(2S)$ over ${\rm Y}(1S)$ and J/$\psi$ over ${\rm Y}(1S)$ as a function of charged-particle multiplicity will also be shown.

   nucl-exhep-exPoS(2021)·1 citation
2. 02*

   The radiative width of the Hoyle state from $\gamma$-ray spectroscopy

   T. Kibédi🇦🇺 · B. Alshahrani · A.E. Stuchbery🇦🇺 · A.C. Larsen🇳🇴 · A. Görgen🇳🇴 · S. Siem🇳🇴 · M. Guttormsen🇳🇴 · F. Giacoppo🇳🇴 · A.I. Morales🇪🇸 · E. Sahin🇳🇴 · G.M. Tveten🇳🇴 · F.L. Bello Garrote🇳🇴 and 8 other authors

   The cascading 3.21 MeV and 4.44 MeV electric quadrupole transitions have been observed from the Hoyle state at 7.65 MeV excitation energy in ${}^{12}$C, excited by the ${}^{12}$C(p,p${}^{\prime }$) reaction at 10.7 MeV proton energy. From the proton-$\gamma$-$\gamma$ triple coincidence data, a value of ${\Gamma }_{\mathrm{rad}}/\Gamma =6.2(6)\times 10^{-4}$ was obtained for the radiative branching ratio. Using our results, together with ${\Gamma }_{\pi }^{E0}/\Gamma$ from Eriksen et al., Phys. Rev. C 102, 024320 and the currently adopted ${\Gamma }_{\pi }(E0)$ values, the radiative width of the Hoyle state is determined as ${\Gamma }_{\mathrm{rad}}=5.1(6)\times 10^{-3}$ eV. This value is about 34% higher than the currently adopted value and will impact on models of stellar evolution and nucleosynthesis.

   nucl-exastro-ph.SRPRL(2020)·41 citations
3. 03*

   Understanding the Enhancement of Scintillation Light in Xenon-Doped Liquid Argon

   D.E. Fields🇺🇸 · R. Gibbons M. Gold🇺🇸 · N. McFadden🇺🇸 · S.R. Elliott🇺🇸 · R. Massarczyk🇺🇸

   Measuring the scintillation light in noble gases is an important detection technique in particle physics. Numerous rare event searches like neutrino beam experiments, neutrino-less double beta-decay, and dark matter searches use argon-based detectors. In liquid argon, the light yield can be enhanced by the addition of a small quantity of xenon, where $\sim 10-1000$ ppm are added. The general enhancement mechanism and its pathway via an energy transfer between argon and xenon excimers is well known, however the importance of absorption of argon excimer emission by atomic xenon has not been fully appreciated. This absorption significantly reduces the light yield in commercially available argon which contains trace amounts ($\sim 0.1$ ppm) of xenon. The addition of a small xenon dopant of $\sim 10$ ppm recovers this lost light resulting in an increased light yield over un-doped argon of about a factor of two. In this paper we introduce a model for the light production in xenon doped argon, including absorption and re-emission, and compare it to the measured time dependence of light emission in xenon-doped argon.

   ↳ physics.ins-dethep-exnucl-exNucl.Instrum.Meth.A(2023)·10 citations
4. 04*

   Relation between transition density and proton inelastic scattering by ${}^{12}$C target at $E_p=$ 65 and 200 MeV

   T. Furumoto🇯🇵 · M. Takashina🇯🇵

   We calculate proton elastic and inelastic scatterings with a microscopic coupled channel (MCC) calculation. The localized diagonal and coupling potentials including the spin-orbit part are obtained by folding a complex $G$-matrix effective nucleon-nucleon interaction with a transition density. This is the first time that the present folding prescription for the spin-orbit part is applied to the proton inelastic scattering, while for the monopole transition only. We apply the MCC calculation to the proton elastic and inelastic (0${}_2^{+}$) scatterings by ${}^{12}$C target at $E_p$ = 65 and 200 MeV. The role of diagonal and coupling potentials for the central and spin-orbit parts is checked. In addition, the relation between the transition density and the proton inelastic scattering is investigated with the modified wave function and the modified transition density. Namely, we perform the investigation with the artificial drastic change rather than fine structural change. The inelastic cross section is sensitive to the strength and shape of the transition density, but the inelastic analyzing power is sensitive only to the shape of that. Finally, we make clear the property of the inelastic analyzing power derived from the transition density without an ambiguity.

   ↳ nucl-thnucl-exPRC(2021)·4 citations
5. 05*

   A search for neutron to mirror-neutron oscillations

   C. Abel (a)🇬🇧 · N. J. Ayres (b)🇨🇭 · G. Ban (c)🇫🇷 · G. Bison (d)🇨🇭 · K. Bodek (e)🇵🇱 · V. Bondar (b)🇨🇭 · E. Chanel (f)🇨🇭 · P.-J. Chiu (b, d)🇨🇭 · C. Crawford (g)🇺🇸 · M. Daum (d)🇨🇭 · R. T. Dinani (h)🇧🇪 · S. Emmenegger (b)🇨🇭 and 31 other authors

   It has been proposed that there could be a mirror copy of the standard model particles, restoring the parity symmetry in the weak interaction on the global level. Oscillations between a neutral standard model particle, such as the neutron, and its mirror counterpart could potentially answer various standing issues in physics today. Astrophysical studies and terrestrial experiments led by ultracold neutron storage measurements have investigated neutron to mirror-neutron oscillations and imposed constraints on the theoretical parameters. Recently, further analysis of these ultracold neutron storage experiments has yielded statistically significant anomalous signals that may be interpreted as neutron to mirror-neutron oscillations, assuming nonzero mirror magnetic fields. The neutron electric dipole moment collaboration performed a dedicated search at the Paul Scherrer Institute and found no evidence of neutron to mirror-neutron oscillations. Thereby, the following new lower limits on the oscillation time were obtained: ${\tau }_{n{n}^{\prime }}>352$s at $B^{\prime }=0$ (95% C.L.), ${\tau }_{n{n}^{\prime }}>6\text{s}$ for all $0.4\mu \text{T}<B^{\prime }<25.7\mu \text{T}$ (95% C.L.), and ${\tau }_{n{n}^{\prime }}/\sqrt{\cos \beta }>9\text{s}$ for all $5.0\mu \text{T}<B^{\prime }<25.4\mu \text{T}$ (95% C.L.), where $\beta$ is the fixed angle between the applied magnetic field and the local mirror magnetic field which is assumed to be bound to the Earth. These new constraints are the best measured so far around $B^{\prime }\sim 10\mu$T, and $B^{\prime }\sim 20\mu$T.

   ↳ hep-phnucl-exquant-phPLB(2021)·55 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.