Mon·Nov 16, 2020Monday·November 16, 2020

1. 01*

   Inclusive heavy-flavour production at central and forward rapidity in Xe-Xe collisions at $\sqrt{s_{\mathrm{NN}}}=5.44$ TeV

   ALICE Collaboration

   The first measurements of the production of muons and electrons from heavy-flavour hadron decays in Xe-Xe collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.44 TeV, using the ALICE detector at the LHC, are reported. The measurement of the nuclear modification factor $R_{\mathrm{AA}}$ is performed as a function of transverse momentum $p_{\mathrm{T}}$ in several centrality classes at forward rapidity ($2.5<y<4$) and midrapidity ($|y|<0.8$) for muons and electrons from heavy-flavour hadron decays, respectively. A suppression by a factor up to about 2.5 compared to the binary-scaled pp reference is observed in central collisions at both central and forward rapidities. The $R_{\mathrm{AA}}$ of muons from heavy-flavour hadron decays is compared to previous measurements in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV. When the nuclear modification factors are compared in the centrality classes 0-10% for Xe-Xe collisions and 10-20% for Pb-Pb collisions, which have similar charged-particle multiplicity density, a similar suppression, with $R_{\mathrm{AA}}\sim 0.4$ in the $p_{\mathrm{T}}$ interval $4<p_{\mathrm{T}}<8$ GeV/$c$, is observed. The comparison of the measured $R_{\mathrm{AA}}$ values in the two collision systems brings new insights on the properties of the quark-gluon plasma by investigating the system-size and path-length dependence of medium-induced parton energy loss. The results of muons and electrons from heavy-flavour hadron decays provide new constraints to model calculations.

   nucl-exhep-exPLB(2021)·14 citations
2. 02*

   Measurement of the Free Neutron Lifetime using the Neutron Spectrometer on NASA's Lunar Prospector Mission

   Jack T. Wilson (1)🇺🇸 · David J. Lawrence (1)🇺🇸 · Patrick N. Peplowski (1)🇺🇸 · Vincent R. Eke (2) · Jacob A. Kegerreis (2) ((1) JHU/APL, (2) Durham, ICC)

   We use data from the Lunar Prospector Neutron Spectrometer to make the second space-based measurement of the free neutron lifetime finding ${\tau }_n=887\pm 14_{\text{stat}}{}_{-3\text{syst}}^{+7}$ s, which is within 1$\sigma$ of the accepted value. This measurement expands the range of planetary bodies where the neutron lifetime has been quantified from space, and by extending the modeling to account for non-uniform elemental composition, we mitigated a significant source of systematic uncertainty on the previous space-based lifetime measurement. This modeling moves space-based neutron lifetime measurement towards the ultimate goal of reducing the magnitude of the systematics on a future space-measurement to the level of those seen in laboratory-based experiments.

   nucl-exPRC(2021)·18 citations
3. 03*

   Calculable microscopic theory for ${}^{12}$C($\alpha ,\gamma$)${}^{16}$O cross section near Gamow window

   Y. Suzuki🇯🇵

   ${}^{12}$C$(\alpha ,\gamma {)}^{16}$O radiative-capture process is a key reaction to produce the element of oxygen in stars. Measuring the cross section near the Gamow window is extremely hard because it is too small. To make a theoretical contribution towards resolving the long-standing problem, I present a microscopic formulation that aims at providing all materials needed to calculate the cross section. The states of ${}^{12}$C and ${}^{16}$O relevant to the reaction are respectively described with fully microscopic 3 $\alpha$-particle and 4 $\alpha$-particle configurations, in which the relative motion among the $\alpha$ particles is expanded in terms of correlated Gaussian basis functions. The configuration space has the advantage of being able to well describe the reduced $\alpha$-width amplitudes of the states of ${}^{16}$O. Both electric dipole and electric quadrupole transitions are responsible for the radiative-capture process. The $\alpha$ particle is described with a $(0s{)}^4$ configuration admixed with a small amount of an isospin $T=1$ impurity component, which is crucially important to account for the isovector electric dipole transition. The isoscalar electric dipole operators are also taken into account up to the first order beyond the long-wavelength approximation. All the necessary ingredients are provided to make the paper self-contained and ready for numerical computations.

   ↳ nucl-thastro-ph.SRnucl-exFew Body Syst.(2021)·4 citations
4. 04*

   Benchmarking Faddeev and transfer-to-the-continuum calculations for (p, pN ) reactions

   M. Gomez-Ramos🇩🇪 · A. Deltuva🇱🇹 · A. M. Moro🇪🇸

   Nucleon-knockout reactions on proton targets (p, pN ) have experienced a renewed interest due to the availability of inverse-kinematics experiment with exotic nuclei. Various theoretical descriptions have been used to describe these reactions, such as the Distorted-Wave Impulse Approximation (DWIA), the Faddeev-type formalism and the Transfer to the Continuum method. Our goal is to benchmark the observables computed with the Faddeev and Transfer to the Continuum formalisms in the intermediate energy regime relevant for the experimental (p, pn) and (p, 2p) studies. In this paper, we analyze the 11 Be(p,pn)10Be reaction for different beam energies, binding energies and orbital quantum numbers with both formalisms to assess their agreement for different observables. We obtain a good agreement in all cases considered, within 10%, when the input potentials are taken consistently and realistically.

   ↳ nucl-thnucl-exPRC(2020)·9 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.