Wed·Nov 11, 2020Wednesday·November 11, 2020

1. 01*

   Measurements of $W$ and $Z/{\gamma }^{\ast }$ cross sections and their ratios in $p+p$ collisions at RHIC

   STAR Collaboration: J. Adam🇺🇸 · L. Adamczyk🇵🇱 · J. R. Adams🇺🇸 · J. K. Adkins🇺🇸 · G. Agakishiev🇷🇺 · M. M. Aggarwal🇮🇳 · Z. Ahammed🇮🇳 · I. Alekseev🇷🇺 · D. M. Anderson🇺🇸 · A. Aparin🇷🇺 · E. C. Aschenauer🇺🇸 · M. U. Ashraf🇨🇳 and 357 other authors

   We report on the $W$ and $Z/{\gamma }^{\ast }$ differential and total cross sections as well as the $W^{+}$/$W^{-}$ and $(W^{+}+W^{-})$/$(Z/{\gamma }^{\ast })$ cross-section ratios measured by the STAR experiment at RHIC in $p+p$ collisions at $\sqrt{s}=500$ GeV and $510$ GeV. The cross sections and their ratios are sensitive to quark and antiquark parton distribution functions. In particular, at leading order, the $W$ cross-section ratio is sensitive to the $\bar{d}/\bar{u}$ ratio. These measurements were taken at high $Q^2\sim M_W^2,M_Z^2$ and can serve as input into global analyses to provide constraints on the sea quark distributions. The results presented here combine three STAR data sets from 2011, 2012, and 2013, accumulating an integrated luminosity of 350 pb${}^{-1}$. We also assess the expected impact that our $W^{+}/W^{-}$ cross-section ratios will have on various quark distributions, and find sensitivity to the $\bar{u}-\bar{d}$ and $\bar{d}/\bar{u}$ distributions.

   nucl-exhep-exPRD(2021)·28 citations
2. 02*

   QCD phase structure in strong magnetic fields

   H.-T. Ding🇨🇳 · S.-T. Li🇨🇳 · Q. Shi🇨🇳 · A. Tomiya🇺🇸 · X.-D. Wang🇨🇳 · Y. Zhang🇨🇳

   In this proceedings we discuss the natural connection between the reduction of neutral pion mass in the vacuum, and the magnetic catalysis as well as the reduction of transition temperature in the external magnetic field. We also present the first results on fluctuations of and correlations among conserved charges in strong magnetic fields from lattice QCD computations.

   ↳ hep-lathep-phhep-thnucl-ex+1Acta Phys.Polon.Supp.(2021)·14 citations
3. 03*

   Three-body structure of ${}^{19}$B: Finite-range effects in two-neutron halo nuclei

   J. Casal🇮🇹 · E. Garrido🇺🇸

   The structure and $B(E1)$ transition strength of ${}^{19}$B are investigated in a ${}^{17}\text{B}+n+n$ model, triggered by a recent experiment showing that ${}^{19}$B exhibits a well pronounced two-neutron halo structure. Preliminary analysis of the experimental data was performed by employing contact $n$-$n$ interactions, which are known to underestimate the $s$-wave content in other halo nuclei such as ${}^{11}$Li. In the present work, the three-body hyperspherical formalism with finite-range two-body interactions is used to describe ${}^{19}$B. In particular, two different finite-range $n$-$n$ interactions will be used, as well as a simple central Gaussian potential whose range is progressively reduced. The purpose is to determine the main properties of the nucleus and investigate how they change when using contact-like $n$-$n$ potentials. Special attention is also paid to the dependence on the prescription used to account for three-body effects, i.e., a three-body force or a density-dependent $n$-$n$ potential. We have found that the three-body model plus finite-range potentials provide a description of ${}^{19}$B consistent with the experimental data. The results are essentially independent of the short-distance details of the two-body potentials, giving rise to an $(s_{1/2}{)}^2$ content of about 55%, clearly larger than the initial estimates. Very little dependence has been found as well on the prescription used for the three-body effects. The total computed $B(E1)$ strength is compatible with the experimental result, although we slightly overestimate the data around the low-energy peak of the $dB(E1)/d\epsilon$ distribution. Finally, we show that a reduction of the $n$-$n$ interaction range produces a significant reduction of the $s$-wave contribution, which then should be expected in calculations using contact interactions.

   ↳ nucl-thnucl-exPRC(2020)·15 citations
4. 04*

   Finite-amplitude method for collective inertia in spontaneous fission

   Kouhei Washiyama · Nobuo Hinohara🇯🇵 · Takashi Nakatsukasa🇯🇵

   Background: Microscopic description of spontaneous fission is one of the most challenging subjects in nuclear physics. It is necessary to evaluate the collective potential and the collective inertia along a fission path for a description of quantum tunneling in spontaneous or low-energy fission. In past studies of the fission dynamics based on nuclear energy density functional (EDF) theory, the collective inertia has been evaluated with the cranking approximation, which neglects dynamical residual effects. Purpose: The purpose is to provide a reliable and efficient method to include dynamical residual effects in the collective inertia for fission dynamics. Methods: We use the local quasiparticle random-phase approximation (LQRPA) to evaluate the collective inertia along a fission path obtained by the constrained Hartree-Fock-Bogoliubov method with the Skyrme EDF. The finite-amplitude method (FAM) with a contour integration technique enables us to efficiently compute the collective inertia in a large model space. Results: We evaluate the FAM-QRPA collective inertia along a symmetric fission path in ${}^{240}$Pu and ${}^{256}$Fm. The FAM-QRPA inertia is significantly larger than the one of the cranking approximation, and shows pronounced peaks around the ground state and the fission isomer. This is due to dynamical residual effects. Conclusions: To describe the spontaneous or low-energy fission, we provide a reliable and efficient method to construct the collective inertia with dynamical residual effects that have been neglected in most of EDF-based works in the past. We show the importance of dynamical residual effects to the collective inertia. This work will be a starting point for a systematic study of fission dynamics in heavy and superheavy nuclei to microscopically describe the nuclear large-amplitude collective motions.

   ↳ nucl-thnucl-exPRC(2021)·26 citations
5. 05*

   Bound on 3+1 active-sterile neutrino mixing from the first four-week science run of KATRIN

   M. Aker · K. Altenmueller · A. Beglarian · J. Behrens · A. Berlev · U. Besserer · B. Bieringer · K. Blaum · F. Block · B. Bornschein · L. Bornschein · M. Boettcher and 117 other authors

   We report on the light sterile neutrino search from the first four-week science run of the KATRIN experiment in~2019. Beta-decay electrons from a high-purity gaseous molecular tritium source are analyzed by a high-resolution MAC-E filter down to 40 eV below the endpoint at 18.57 keV. We consider the framework with three active neutrinos and one sterile neutrino of mass $m_4$. The analysis is sensitive to a fourth mass state $m_4^2\lesssim$ 1000 eV${}^2$ and to active-to-sterile neutrino mixing down to $|U_{e4}{|}^2\gtrsim 2\cdot 10^{-2}$. No significant spectral distortion is observed and exclusion bounds on the sterile mass and mixing are reported. These new limits supersede the Mainz results and improve the Troitsk bound for $m_4^2<$ 30 eV${}^2$. The reactor and gallium anomalies are constrained for $100<\Delta m_{41}^2<1000$ eV${}^2$.

   ↳ hep-exnucl-exPRL(2021)·72 citations
6. 06*

   Observation of forward neutron multiplicity dependence of dimuon acoplanarity in ultraperipheral Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=$ 5.02 TeV

   CMS Collaboration

   The first measurement of the dependence of $\gamma \gamma$ $\to$ ${\mu }^{+}{\mu }^{-}$ production on the multiplicity of neutrons emitted very close to the beam direction in ultraperipheral heavy ion collisions is reported. Data for lead-lead interactions at $\sqrt{s_{\mathrm{NN}}}=$ 5.02 TeV, with an integrated luminosity of approximately 1.5 nb${}^{-1}$, were collected using the CMS detector at the LHC. The azimuthal correlations between the two muons in the invariant mass region 8 $<$ $m_{\mu \mu }$ $<$ 60 GeV are extracted for events including 0, 1, or at least 2 neutrons detected in the forward pseudorapidity range $|\eta |$ $>$ 8.3. The back-to-back correlation structure from leading-order photon-photon scattering is found to be significantly broader for events with a larger number of emitted neutrons from each nucleus, corresponding to interactions with a smaller impact parameter. This observation provides a data-driven demonstration that the average transverse momentum of photons emitted from relativistic heavy ions has an impact parameter dependence. These results provide new constraints on models of photon-induced interactions in ultraperipheral collisions. They also provide a baseline to search for possible final-state effects on lepton pairs caused by traversing a quark-gluon plasma produced in hadronic heavy ion collisions.

   ↳ hep-exnucl-exPRL(2021)·85 citations
7. 07*

   Jas4pp -- a Data-Analysis Framework for Physics and Detector Studies

   S. V. Chekanov🇺🇸 · G. Gavalian🇺🇸 · N. A. Graf🇺🇸

   This paper describes the Jas4pp framework for exploring physics cases and for detector-performance studies of future particle collision experiments. Jas4pp is a multi-platform Java program for numeric calculations, scientific visualization in 2D and 3D, storing data in various file formats and displaying collision events and detector geometries. It also includes complex data-analysis algorithms for function minimisation, regression analysis, event reconstruction (such as jet reconstruction), limit settings and other libraries widely used in particle physics. The framework can be used with several scripting languages, such as Python/Jython, Groovy and JShell. Several benchmark tests discussed in the paper illustrate significant improvements in the performance of the Groovy and JShell scripting languages compared to the standard Python implementation in C. The improvements for numeric computations in Java are attributed to recent enhancements in the Java Virtual Machine.

   ↳ physics.comp-phhep-phnucl-exComput.Phys.Commun.(2021)·3 citations
8. 08*

   40 Gbps Readout interface STARE for the AGATA Project

   N. Karkour🇫🇷 · V. Alaphilippe🇫🇷 · J. Collado🇪🇸 · N. Dosme🇫🇷 · L. Gibelin🇫🇷 · V. Gonzalez🇪🇸 · X. Grave🇫🇷 · J. Jacob🇫🇷 · X. Lafay🇫🇷 · E. Legay🇫🇷 · D. Linget🇫🇷 · A. Pullia🇮🇹 and 4 other authors

   The Advanced GAmma Tracking Array (AGATA) multi detector spectrometer will provide precise information for the study of the properties of the exotic nuclear matter (very unbalanced proton (Z) and neutron (N) numbers) along proton- and neutron- drip lines and of super-heavy nuclei. This is done using the latest technology of particle accelerators. The AGATA spectrometer consists of 180 high purity Germanium detectors. Each detector is segmented into 38 segments. The very harsh project requirements are to measure gamma ray energies with very high resolution (< 1x 10 -3) at a high detector counting rate (50 Kevents / sec / crystal). This results in a very high data transfer rate per crystal (5 to 8 Gbps). The 38 segments are sampled @ 100 MHz with 14 bits of resolution. The samples are continuously transferred to the CAP module which reduces the data rate from 64 Gbps to 5 Gbps. The CAP module also adds continuous monitoring data which results in total outgoing data rate of 10 Gbps. The STARE module is designed to fit between the CAP module and the computer farm. It will package the data from the CAP module and transmit it to the server farm using a 10 Gbps UDP connection with a delivery insurance mechanism implemented to ensure that all data is transferred.

   ↳ physics.ins-deteess.SPnucl-exIEEE Trans.Nucl.Sci.(2021)·1 citation

* 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.