Wed·Nov 30, 2022Wednesday·November 30, 2022

1. 01*

   Precision Studies of QCD in the Low Energy Domain of the EIC

   V. Burkert · L. Elouadrhiri · A. Afanasev · J. Arrington · M. Contalbrigo · W. Cosyn · A. Deshpande · D. Glazier · X. Ji · S. Liuti · Y. Oh · D. Richards · T. Satogata · A. Vossen

   The manuscript focuses on the high impact science of the EIC with objective to identify a portion of the science program for QCD precision studies that requires or greatly benefits from high luminosity and low center-of-mass energies. The science topics include (1) Generalized Parton Distributions, 3D imagining and mechanical properties of the nucleon (2) mass and spin of the nucleon (3) Momentum dependence of the nucleon in semi-inclusive deep inelastic scattering (4) Exotic meson spectroscopy (5) Science highlights of nuclei (6) Precision studies of Lattice QCD in the EIC era (7) Science of far-forward particle detection (8) Radiative effects and corrections (9) Artificial Intelligence (10) EIC interaction regions for high impact science program with discovery potential. This paper documents the scientific basis for supporting such a program and helps to define the path toward the realization of the second EIC interaction region.

   nucl-exhep-exhep-lathep-ph+1PPNP(2023)·95 citations
2. 02*

   Vector meson photoproduction in UPCs with FoCal

   Alexander Bylinkin🇳🇴 · Joakim Nystrand🇳🇴 · Daniel Tapia Takaki🇺🇸

   We discuss the physics prospects of photon-induced measurements using the high-granularity FoCal detector to be installed at the ALICE experiment, covering the pseudorapidity interval $3.4\le \eta \le 5.8$. This new detector, scheduled to be in operation from Run 4, will explore the small Bjorken-$x$ physics region in an unprecedented way. In this region the gluon saturation phenomenon is expected to be dominant. Combined with the rest of the ALICE subdetectors, including the zero degree calorimenters, FoCal will serve to reconstruct in a model-independent way the measured photoproduction cross sections for vectors mesons in a wide range of photon-target energies, down to $x$ values of about $7\times 10^{-6}$ and $2\times 10^{-6}$ in ultra-peripheral photon--proton and photon--lead collisions, respectively.

   nucl-exhep-phphysics.ins-detJ.Phys.G(2023)·20 citations
3. 03*

   QRPA calculations for M1 transitions with the noniterative finite amplitude method and the application to neutron radiative capture cross sections

   Hirokazu Sasaki🇺🇸 · Toshihiko Kawano🇺🇸 · Ionel Stetcu🇺🇸

   We derive the equations of quasiparticle random-phase approximation (QRPA) based on the finite amplitude method (FAM) with the Hartree-Fock+BCS (HF+BCS) single-particle states, and calculate the magnetic dipole (M1) transition for deformed gadolinium isotopes. Our QRPA calculation shows both large spin-flip transitions in the 5 to 10 MeV excitation energy and the low energy orbital transition that would correspond to the M1 scissors mode observed in nuclear experiments. Then, we calculate neutron capture reactions based on the statistical Hauser-Feshbach theory with the photoabsorption cross sections given by QRPA. We find that the capture cross section is enhanced due to the contribution from the low energy M1 transition although the calculated capture cross section still underestimates the experimental data. This issue in the calculated capture cross section could be improved by uncertainties of low energy E1 transition neglected in our QRPA calculation.

   ↳ nucl-thnucl-exPRC(2023)·8 citations
4. 04*

   Radiative corrections to inverse muon decay for accelerator neutrinos

   Oleksandr Tomalak🇺🇸 · Kaushik Borah🇺🇸 · Richard J. Hill🇺🇸 · Kevin S. McFarland🇺🇸 · Daniel Ruterbories🇺🇸

   Inverse muon decay (${\nu }_{\mu }{e}^{-}\to {\nu }_e{\mu }^{-}$) is a promising tool to constrain neutrino fluxes with energies $E_{\nu }\ge 10.9\mathrm{GeV}$. Radiative corrections introduce percent-level distortions to energy spectra of outgoing muons and depend on experimental details. In this paper, we calculate radiative corrections to the scattering processes ${\nu }_{\mu }{e}^{-}\to {\nu }_e{\mu }^{-}$ and ${\bar{\nu }}_e{e}^{-}\to {\bar{\nu }}_{\mu }{\mu }^{-}$. We present the muon energy spectrum for both channels, double-differential distributions in muon energy and muon scattering angle and in photon energy and photon scattering angle, and the photon energy spectrum for the dominant ${\nu }_{\mu }{e}^{-}\to {\nu }_e{\mu }^{-}$ process. Our results clarify and extend the region of applicability of previous results in the literature for the double differential distribution in muon energy and photon energy, and in the muon energy spectrum with a radiated photon above a threshold energy. We provide analytic expressions for single, double and triple differential cross sections, and discuss how radiative corrections modify experimentally interesting observable distributions.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2023)·5 citations
5. 05*

   Towards clarifying the possibility of observation of the LHCb hidden-charm pentaquarks $P_c^{+}(4312)$, $P_c^{+}(4337)$, $P_c^{+}(4440)$ and $P_c^{+}(4457)$ in near-threshold charmonium photoproduction off protons and nuclei

   E. Ya. Paryev🇷🇺

   We study the near-threshold $J/\psi$ meson photoproduction from protons and nuclei by considering incoherent direct non-resonant ($\gamma p\to J/\psi p$, $\gamma n\to J/\psi n$) and two-step resonant ($\gamma p\to P_{ci}^{+}\to J/\psi p$, $\gamma n\to P_{ci}^0\to J/\psi n$, $i=1$, 2, 3, 4; $P_{c1}^{+,0}=P_c^{+,0}(4312)$, $P_{c2}^{+,0}=P_c^{+,0}(4337)$, $P_{c3}^{+,0}=P_c^{+,0}(4440)$, $P_{c4}^{+,0}=P_c^{+,0}(4457)$) charmonium production processes. We calculate the absolute excitation functions, energy and momentum distributions for the non-resonant, resonant and for the combined (non-resonant plus resonant) production of $J/\psi$ mesons on protons as well as, using the nuclear spectral function approach, on carbon and tungsten target nuclei at near-threshold incident photon energies by assuming the spin-parity assignments of the hidden-charm resonances $P_c^{+,0}(4312)$, $P_c^{+,0}(4337)$, $P_c^{+,0}(4440)$ and $P_c^{+,0}(4457)$ as $J^P=(1/2{)}^{-}$, $J^P=(1/2{)}^{-}$, $J^P=(1/2{)}^{-}$ and $J^P=(3/2{)}^{-}$ within three different realistic scenarios for the branching ratios of their decays to the $J/\psi p$ and $J/\psi n$ modes (0.25, 0.5 and 1%). We show that will be very hard to measure the $P_{ci}^{+}$ pentaquark states through the scan of the $J/\psi$ total photoproduction cross section on a proton target in the near-threshold energy region around the resonant photon energies of 9.44, 9.554, 10.04 and 10.12 GeV if these branching ratios $\sim$ 1% and less. We also demonstrate that at these photon beam energies the $J/\psi$ energy and momentum combined distributions considered reveal distinct sensitivity to the above scenarios, respectively, at "low" $J/\psi$ total energies and momenta, which implies that they may be an important tool to provide further evidence for the existence of the pentaquark $P_{ci}^{+}$ and $P_{ci}^0$ resonances.

   ↳ hep-phhep-exnucl-exNPA(2023)·6 citations
6. 06*

   Observation of Time-Dependent Internal Charge Amplification in a Planar Germanium Detector at Cryogenic Temperature

   P. Acharya🇺🇸 · M. Fritts🇺🇸 · D.-M. Mei🇺🇸 · V. Mandic🇺🇸 · G.-J. Wang🇺🇸 · R. Mahapatra🇺🇸 · M. Platt🇺🇸

   For the first time, time-dependent internal charge amplification through impact ionization has been observed in a planar germanium (Ge) detector operated at cryogenic temperature. In a time period of 30 and 45 minutes after applying a bias voltage, the charge energy corresponding to a baseline of the 59.54 keV $\gamma$ rays from a ${}^{241}$Am source is amplified for a short period of time and then decreases back to the baseline. The amplification of charge energy depends strongly on the applied positive bias voltage with drifting holes across the detector. No such phenomenon is visible with drifting electrons across the detector. We find that the observed charge amplification is dictated by the impact ionization of charged states, which has a strong correlation with impurity level and applied electric field. We analyze the dominant physics mechanisms that are responsible for the creation and the impact ionization of charged states. Our analysis suggests that the appropriate level of impurity in a Ge detector can enhance charge yield through the impact ionization of charged states to achieve extremely low-energy detection threshold ($<$ 10 meV) for MeV-scale dark matter searches if the charge amplification can be stabilized.

   ↳ physics.ins-detcond-mat.mtrl-scihep-exnucl-exEPJC(2023)·2 citations
7. 07*

   The 3D structure of anisotropic flow in small collision systems at the Relativistic Heavy Ion Collider

   Wenbin Zhao🇺🇸 · Sangwook Ryu🇺🇸 · Chun Shen🇺🇸 · Björn Schenke🇺🇸

   We present (3+1)D dynamical simulations of asymmetric nuclear collisions at the Relativistic Heavy Ion Collider (RHIC). Employing a dynamical initial state model coupled to (3+1)D viscous relativistic hydrodynamics, we explore the rapidity dependence of anisotropic flow in the RHIC small system scan at 200 GeV center of mass energy. We calibrate parameters to describe central ${}^3$He+Au collisions and make extrapolations to d+Au and p+Au collisions. Our calculations demonstrate that approximately 50% of the $v_3(p_T)$ difference between the measurements by the STAR and PHENIX Collaborations can be explained by the use of reference flow vectors from different rapidity regions. This emphasizes the importance of longitudinal flow decorrelation for anisotropic flow measurements in asymmetric nuclear collisions, and the need for (3+1)D simulations. We also present results for the beam energy dependence of particle spectra and anisotropic flow in d+Au collisions.

   ↳ nucl-thhep-phnucl-exPRC(2023)·60 citations
8. 08*

   Probing initial baryon stopping and equation of state with rapidity-dependent directed flow of identified particles

   Lipei Du🇨🇦 · Chun Shen🇺🇸 · Sangyong Jeon🇨🇦 · Charles Gale🇨🇦

   Using a (3+1)-dimensional hybrid framework with parametric initial conditions, we study the rapidity-dependent directed flow $v_1(y)$ of identified particles, including pions, kaons, protons, and lambdas in heavy-ion collisions. Cases involving Au+Au collisions are considered, performed at $\sqrt{s_{\mathrm{NN}}}$ ranging from 7.7 to 200 GeV. The dynamics in the beam direction is constrained using the measured pseudo-rapidity distribution of charged particles and the net proton rapidity distribution. Within this framework, the directed flow of mesons is driven by the sideward pressure gradient from the tilted source, and that of baryons mainly due to the initial asymmetric baryon distribution with respect to the beam axis driven by the transverse expansion. Our approach successfully reproduces the rapidity- and beam energy-dependence of $v_1$ for both mesons and baryons. We find that the $v_1(y)$ of baryons has strong constraining power on the initial baryon stopping, and together with that of mesons, the directed flow probes the equation of state of the dense nuclear matter at finite chemical potentials.

   ↳ nucl-thhep-phnucl-exPRC(2023)·42 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.