Thu·Mar 25, 2021Thursday·March 25, 2021

1. 01*

   Double deeply virtual Compton scattering with positron beams at SoLID

   S. Zhao🇫🇷 · A. Camsonne🇺🇸 · D. Marchand🇫🇷 · M. Mazouz🇹🇳 · N. Sparveris🇺🇸 · S. Stepanyan🇺🇸 · E. Voutier🇫🇷 · Z. W. Zhao🇺🇸

   Double Deeply Virtual Compton Scattering (DDVCS) is the only experimental channel for the determination of the dependence of the Generalized Parton Distributions (GPDs) on both the average and the transferred momentum independently. The physics observables of the electron induced di-muon production reaction $\text{vv}{e}^{\pm }p\to e^{\pm }p{\mu }^{+}{\mu }^{-}$ off unpolarized hydrogen are discussed. Their measurement with the high luminosity and large acceptance SoLID spectrometer at the Thomas Jefferson National Accelerator Facility, using polarized and unpolarized positron and electron beams at 11 GeV is investigated. This experimental configuration is shown to provide unprecedented access to the GPDs with the determination of the real and imaginary parts of the Compton Form Factor $\mathcal{H}$ in an unexplored phase space, and to enable an exploratory investigation of higher twist effects.

   nucl-exnucl-thEPJA(2021)·15 citations
2. 02*

   Influence of the treatment of initialization and mean-field potential on the neutron to proton yield ratios

   Junping Yang🇨🇳 · Yingxun Zhang🇨🇳 · Ning Wang🇨🇳 · Zhuxia Li🇨🇳

   In this work, we firstly investigate how to reproduce and how well one can reproduce the Woods-Saxon density distribution of initial nuclei in the framework of the improved quantum molecular dynamics model. Then, we propose a new treatment for the initialization of nuclei which is correlated with the nucleonic mean-field potential by using the same potential energy density functional. In the mean field potential, the three-body force term is accurately calculated. Based on the new version of the model, the influences of precise calculations of the three-body force term, the slope of symmetry energy, the neutron-proton effective mass splitting, and the width of the wave packet on heavy ion collision observables, such as the neutron to proton yield ratios for emitted free nucleons [$R(n/p)$] and for coalescence invariant nucleons [$R_{ci}(n/p)$] for ${}^{124}$Sn+${}^{112}$Sn at the beam energy of 200 MeV per nucleon, are discussed. Our calculations show that the spectra of neutron to proton yield ratios [$R(n/p)$] can be used to probe the slope of symmetry energy ($L$) and the neutron-proton effective mass splitting. In detail, the $R(n/p)$ in the low kinetic energy region can be used to probe the slope of symmetry energy ($L$). With a given $L$, the inclination of $R(n/p)$ to kinetic energy ($E_k$) can be used to probe the effective mass splitting. In the case where the neutron-proton effective mass splitting is fixed, $R(n/p)$ at high kinetic energy can also be used to learn the symmetry energy at suprasaturation density.

   ↳ nucl-thnucl-exPRC(2021)·21 citations
3. 03*

   Updated systematics of intermediate-energy single-nucleon removal cross sections

   J.A. Tostevin🇬🇧 · A. Gade🇺🇸

   The body of experimental measurements of intermediate-energy reactions that remove a single nucleon from a secondary beam of neutron- or proton-rich nuclei continues to grow. These data have been analysed consistently using an approximate, eikonal-model treatment of the reaction dynamics combined with appropriate shell-model descriptions of the projectile initial state, the bound final states spectrum of the reaction residue and single-particle removal strengths computed from their wave-function overlaps. The systematics of the ratio $R_s$ of the measured inclusive cross-section to all bound final states and the calculated cross-section to bound shell-model states -- in different regions of the nuclear chart and involving both very weakly-bound and strongly-bound valence nucleons -- is important in relating the empirically deduced orbital occupancies to those from the best available shell-model predictions. Importantly, several new higher-energy measurements, for which the sudden-approximation aspect of the dynamical description is placed on an even stronger footing, now supplement the previously-analysed measurements. These additional data sets are discussed. Their $R_s$ values are shown to conform to and reinforce the earlier-observed systematics, with no indication that the approximately linear reduction in $R_s$ with increasing nucleon separation energy is a consequence of a breakdown of the sudden approximation.

   ↳ nucl-thnucl-exPRC(2021)·72 citations
4. 04*

   $g$-factor and static quadrupole moment of ${}^{135}$Pr, ${}^{105}$Pd, and ${}^{187}$Au in wobbling motion

   C. Broocks🇩🇪 · Q. B. Chen🇩🇪 · N. Kaiser🇩🇪 · Ulf-G. Meißner🇩🇪

   The $g$-factor and static quadrupole moment of the nuclides ${}^{135}$Pr, ${}^{105}$Pd, and ${}^{187}$Au in the wobbling motion are investigated in the particle-rotor model as functions of the total spin $I$. The $g$-factor of ${}^{105}\mathrm{Pd}$ increases with increasing $I$, due to the negative gyromagnetic ratio of a neutron valence-neutron. This behavior is in contrast to the decreasing $g$-factor of the other two nuclides, ${}^{135}$Pr and ${}^{187}$Au, which feature a valence-proton. The static quadrupole moment $Q$ depends on all three expectation values of the total angular momentum. It is smaller in the yrast band than in the wobbling band for the transverse wobblers ${}^{135}$Pr and ${}^{105}$Pd, while larger for the longitudinal wobbler ${}^{187}$Au.

   ↳ nucl-thnucl-exEPJA(2021)·16 citations
5. 05*

   Partial dynamical symmetry from energy density functionals

   K. Nomura🇭🇷 · N. Gavrielov🇮🇱 · A. Leviatan🇮🇱

   We show that the notion of partial dynamical symmetry is robust and founded on a microscopic many-body theory of nuclei. Based on the universal energy density functional framework, a general quantal boson Hamiltonian is derived and shown to have essentially the same spectroscopic character as that predicted by the partial SU(3) symmetry. The principal conclusion holds in two representative classes of energy density functionals: nonrelativistic and relativistic. The analysis is illustrated in application to the axially-deformed nucleus ${}^{168}$Er.

   ↳ nucl-thnucl-exPRC(2021)·5 citations
6. 06*

   Effects of Pauli blocking and in-medium nucleon-nucleon cross sections on the stopping power at low-intermediate energy heavy ion collisions

   Xiang Chen🇨🇳 · Yingxun Zhang🇨🇳 · Zhuxia Li🇨🇳

   Three typical algorithms of Pauli blocking in the quantum molecular dynamics type models are investigated in the nuclear matter, the nucleus and the heavy ion collisions. The calculations in nuclear matter show that the blocking ratios obtained with the three algorithms are underestimated 13-25\% compared to the analytical values of blocking ratios. For the finite nucleus, the spurious collisions occur around the surface of the nucleus owing to the defects of Pauli blocking algorithms. In the simulations of heavy ion collisions, the uncertainty of stopping power from different Pauli blocking algorithms is less than 5\%. Furthermore, the in-medium effects of nucleon-nucleon ($NN$) cross sections on the nuclear stopping power are discussed. Our results show that the transport models calculations with free $NN$ cross sections result in the stopping power decreasing with the beam energy at the beam energy less than 300 MeV/u. To increase or decrease the values of stopping power, an enhanced or suppressed model dependent in-medium $NN$ cross section is required.

   ↳ nucl-thnucl-ex0 citations
7. 07*

   Invariant Jet Mass Measurements in $pp$ Collisions at $\sqrt{s}=200$ GeV at RHIC

   STAR Collaboration: M. S. Abdallah🇪🇬 · J. Adam🇺🇸 · L. Adamczyk🇵🇱 · J. R. Adams🇺🇸 · J. K. Adkins🇺🇸 · G. Agakishiev🇷🇺 · I. Aggarwal🇮🇳 · M. M. Aggarwal🇮🇳 · Z. Ahammed🇮🇳 · I. Alekseev🇷🇺 · D. M. Anderson🇺🇸 · A. Aparin🇷🇺 and 377 other authors

   We present the first inclusive measurements of the invariant and SoftDrop jet mass in proton-proton collisions at $\sqrt{s}=200$ GeV at STAR. The measurements are fully corrected for detector effects, and reported differentially in both the jet transverse momentum and jet radius parameter. We compare the measurements to established leading-order Monte Carlo event generators and find that STAR-tuned PYTHIA-6 reproduces the data, while LHC tunes of PYTHIA-8 and HERWIG-7 do not agree with the data, providing further constraints on parameter tuning. Finally, we observe that SoftDrop grooming, for which the contribution of wide-angle non-perturbative radiation is suppressed, shifts the jet mass distributions into closer agreement with the partonic jet mass as determined by both PYTHIA-8 and a next-to-leading-logarithmic accuracy perturbative QCD calculation. These measurements complement recent LHC measurements in a different kinematic region, as well as establish a baseline for future jet mass measurements in heavy-ion collisions at RHIC.

   ↳ hep-exnucl-exPRD(2021)·33 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.