Tue·Jul 13, 2021Tuesday·July 13, 2021

1. 01*

   First direct measurement of ${}^{59}$Cu(p,$\alpha$)${}^{56}$Ni: A step towards constraining the Ni-Cu cycle in the Cosmos

   J.S. Randhawa · R. Kanungo🇨🇦 · J. Refsgaard · P. Mohr🇭🇺 · T. Ahn🇺🇸 · M. Alcorta · C. Andreoiu🇨🇦 · S. S.Bhattacharjee · B. Davids🇨🇦 · G. Christian · A. A. Chen🇹🇼 · R. Coleman🇨🇦 and 25 other authors

   Reactions on the proton-rich nuclides drive the nucleosynthesis in Core-Collapse Supernovae (CCSNe) and in X-ray bursts (XRBs). CCSNe eject the nucleosynthesis products to the interstellar medium and hence are a potential inventory of p-nuclei, whereas in XRBs nucleosynthesis powers the light curves. In both astrophysical sites the Ni-Cu cycle, which features a competition between ${}^{59}$Cu(p,$\alpha$)${}^{56}$Ni and ${}^{59}$Cu(p,$\gamma$)${}^{60}$Zn, could potentially halt the production of heavier elements. Here, we report the first direct measurement of ${}^{59}$Cu(p,$\alpha$)${}^{56}$Ni using a re-accelerated ${}^{59}$Cu beam and cryogenic solid hydrogen target. Our results show that the reaction proceeds predominantly to the ground state of ${}^{56}$Ni and the experimental rate has been found to be lower than Hauser-Feshbach-based statistical predictions. New results hint that the $\nu p$-process could operate at higher temperatures than previously inferred and therefore remains a viable site for synthesizing the heavier elements.

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

   Coulomb field correction due to virtual $e^{+}{e}^{-}$ production in heavy ion collisions

   Thomas Settlemyre🇺🇸 · Aldo Bonasera🇺🇸 · Hua Zheng🇨🇳

   The correction to the Coulomb energy due to virtual production of $e^{+}{e}^{-}$ pairs, which is on the order of one percent of the Coulomb energy at nuclear scales is discussed. The effects of including a pair-production term in the semi-empirical mass formula and the correction to the Coulomb barrier for a handful of nuclear collisions using the Bass and Coulomb potentials are studied. With an eye toward future work using Constrained Molecular Dynamics (CoMD) model, we also calculate the correction to the Coulomb energy and force between protons after folding with a Gaussian spatial distribution.

   ↳ nucl-thnucl-exNPA(2021)·4 citations
3. 03*

   Test of the hyperon-nucleon interaction within leading order covariant chiral effective field theory

   Jing Song🇨🇳 · Zhi-Wei Liu🇨🇳 · Kai-Wen Li🇨🇳 · Li-Sheng Geng🇨🇳

   Motivated by the recent experimental measurements of differential cross sections of the ${\Sigma }^{-}p$ elastic scattering in the momentum range of $470$ to $850$ MeV$/c$ by the J-PARC E$40$ experiment, we extend our previous studies of $S=-1$ hyperon-nucleon interactions to relatively higher energies up to $900$ MeV$/c$ for both the coupled-channel $\Lambda p\to (\Lambda p,{\Sigma }^{+}n,{\Sigma }^{0}p)$, ${\Sigma }^{-}p\to (\Lambda n,{\Sigma }^{0}n,{\Sigma }^{-}p)$ and single-channel ${\Sigma }^{+}p\to {\Sigma }^{+}p$ reactions. We show that although the leading order covariant chiral effective field theory is only constrained by the low energy data, it can describe the high energy data reasonably well, in particular, the J-PARC E40 differential cross sections. The predicted cusp structure close to the $\Sigma N$ threshold in the $\Lambda p\to \Lambda p$ reaction agrees with the latest ALICE observation as well as with the results of the next-to-leading order heavy baryon chiral effective theory. On the other hand, the comparison with the latest CLAS data on the $\Lambda p$ cross sections between 0.9 and 2.0 GeV$/c$ clearly indicates the need of higher order chiral potentials for such high momenta. This is also the case for the latest J-PARC data on the $\Sigma p\to \Lambda n$ differential cross sections. Nevertheless, even for these cases, the predictions are in qualitative agreement with the data, albeit with large uncertainties, implying that the predicted total and differential cross sections are of relevance for ongoing and planned experiments.

   ↳ nucl-thhep-exhep-lathep-ph+1PRC(2022)·32 citations
4. 04*

   (3+1)-D viscous hydrodynamics CLVisc at finite net baryon density: identified particle spectra, anisotropic flows and flow fluctuations across BES energies

   Xiang-Yu Wu🇨🇳 · Guang-You Qin🇨🇳 · Long-Gang Pang🇨🇳 · Xin-Nian Wang🇨🇳

   To study the bulk properties of the quark-gluon-plasma (QGP) produced at the beam energy scan (BES) energies at the Relativistic Heavy Ion Collider (RHIC), we extend the (3+1)-dimensional viscous hydrodynamics CLVisc to include net baryon number conservation and Israel-Stewart-like equation for baryon diffusion with the NEOS-BQS equation of state, fluctuating initial conditions from Monte-Carlo Glauber model, and the afterburner SMASH. This integrated framework is shown to provide a good description of identified particle spectra, mean transverse momenta and anisotropic flows for different centralities and over a wide range of collision energies (7.7-62.4 GeV). It is found that the mean momenta of identified particles and anisotropic flows increases mildly with the collision energy due to larger radial flow. We further compute the multiple-particle cumulant ratio $v_2\{4\}/v_2\{2\}$ of elliptic flow across BES energies, and find that the relative fluctuations of elliptic flow are insensitive to the collision energy, consistent with the preliminary STAR data. Our model provides a benchmark for understanding the RHIC-BES data and studying the critical properties and phase structure of hot and dense QCD matter.

   ↳ hep-phnucl-exnucl-thPRC(2022)·101 citations
5. 05*

   Evolution of nuclear charge radii in copper and indium isotopes

   Rong An🇺🇸 · Xiang Jiang · Li-Gang Cao · Feng-Shou Zhang🇨🇳

   Systematic trends in nuclear charge radii are of great interest due to universal shell effects and odd-even staggering (OES). The modified root mean square (rms) charge radius formula, which phenomenologically accounts for the formation of neutron-proton ($np$) correlations, is here applied for the first time to the study of odd-$Z$ copper and indium isotopes. Theoretical results obtained by the relativistic mean field (RMF) model with NL3, PK1 and NL3${}^{\ast }$ parameter sets are compared with experimental data. Our results show that both OES and the abrupt changes across $N=50$ and $82$ shell closures are clearly reproduced in nuclear charge radii. The inverted parabolic-like behaviors of rms charge radii can also be described remarkably well between two neutron magic numbers, namely $N=28$ to $50$ for copper isotopes and $N=50$ to $82$ for indium isotopes. This implies that the $np$-correlations play an indispensable role in quantitatively determining the fine structures of nuclear charge radii along odd-$Z$ isotopic chains. Also, our conclusions have almost no dependence on the effective forces.

   ↳ nucl-thnucl-exCPC(2022)·10 citations
6. 06*

   Resonances of $A=4$ $T=1$ isospin triplet states within the \textit{ab initio} no-core Gamow shell model

   J. G. Li🇨🇳 · N. Michel🇨🇳 · W. Zuo🇨🇳 · F. R. Xu🇨🇳

   The $A=4$ nuclei, i.e., ${}^4$H, ${}^4$He and ${}^4$Li, establish an interesting isospin $T=1$ isobaric system. ${}^4$H and ${}^4$Li are unbound broad resonances, whereas ${}^4$He is deeply bound in its ground state but unbound in all its excited states. The present situation is that experiments so far have not given consistent data on the resonances. Few-body calculations have well studied the scatterings of the $4N$ systems. In the present work, we provide many-body calculations of the broad resonance structures, in an \textit{ab initio} framework with modern realistic interactions. It occurs that, indeed, ${}^4$H, ${}^4$Li and excited ${}^4$He are broad resonances, which is in accordance with experimental observations. The calculations also show that the first $1^{-}$ excited state almost degenerates with the $2^{-}$ ground state in the pair of mirror isobars of ${}^4$H and ${}^4$Li, which may suggest that the experimental data on energy and width are the mixture of the ground state and the first excited state. The $T=1$ isospin triplet formed with an excited state of ${}^4$He and ground states of ${}^4$H and ${}^4$Li is studied, focusing on the effect of isospin symmetry breaking.

   ↳ nucl-thnucl-exPRC(2021)·34 citations
7. 07*

   A Detailed Examination of Astrophysical Constraints on the Symmetry Energy and the Neutron Skin of ${}^{208}$Pb with Minimal Modeling Assumptions

   Reed Essick🇺🇸 · Philippe Landry🇨🇦 · Achim Schwenk🇩🇪 · Ingo Tews🇺🇸

   The symmetry energy and its density dependence are pivotal for many nuclear physics and astrophysics applications, as they determine properties ranging from the neutron-skin thickness of nuclei to the crust thickness and the radius of neutron stars. Recently, PREX-II reported a value of $0.283\pm 0.071$ fm for the neutron-skin thickness of ${}^{208}$Pb, $R_{\mathrm{skin}}^{{}^{208}\text{Pb}}$, implying a symmetry-energy slope parameter $L$ of $106\pm 37$ MeV, larger than most ranges obtained from microscopic calculations and other nuclear experiments. We use a nonparametric equation of state representation based on Gaussian processes to constrain the symmetry energy $S_0$, $L$, and $R_{\mathrm{skin}}^{{}^{208}\text{Pb}}$ directly from observations of neutron stars with minimal modeling assumptions. The resulting astrophysical constraints from heavy pulsar masses, LIGO/Virgo, and NICER favor smaller values of the neutron skin and $L$, as well as negative symmetry incompressibilities. Combining astrophysical data with chiral effective field theory ($\chi$EFT) and PREX-II constraints yields $S_0=33.0_{-1.8}^{+2.0}$ MeV, $L=53_{-15}^{+14}$ MeV, and $R_{\mathrm{skin}}^{{}^{208}\text{Pb}}=0.17_{-0.04}^{+0.04}$ fm. We also examine the consistency of several individual $\chi$EFT calculations with astrophysical observations and terrestrial experiments. We find that there is only mild tension between $\chi$EFT, astrophysical data, and PREX-II's $R_{\mathrm{skin}}^{{}^{208}\mathrm{Pb}}$ measurement ($p$-value $=12.3\%$) and that there is excellent agreement between $\chi$EFT, astrophysical data, and other nuclear experiments.

   ↳ nucl-thastro-ph.HEnucl-exPRC(2021)·97 citations
8. 08*

   An equation-of-state-meter for CBM using PointNet

   Manjunath Omana Kuttan🇩🇪 · Kai Zhou🇩🇪 · Jan Steinheimer🇩🇪 · Andreas Redelbach🇩🇪 · Horst Stoecker🇩🇪

   A novel method for identifying the nature of QCD transitions in heavy-ion collision experiments is introduced. PointNet based Deep Learning (DL) models are developed to classify the equation of state (EoS) that drives the hydrodynamic evolution of the system created in Au-Au collisions at 10 AGeV. The DL models were trained and evaluated in different hypothetical experimental situations. A decreased performance is observed when more realistic experimental effects (acceptance cuts and decreased resolutions) are taken into account. It is shown that the performance can be improved by combining multiple events to make predictions. The PointNet based models trained on the reconstructed tracks of charged particles from the CBM detector simulation discriminate a crossover transition from a first order phase transition with an accuracy of up to 99.8%. The models were subjected to several tests to evaluate the dependence of its performance on the centrality of the collisions and physical parameters of fluid dynamic simulations. The models are shown to work in a broad range of centralities (b=0-7 fm). However, the performance is found to improve for central collisions (b=0-3 fm). There is a drop in the performance when the model parameters lead to reduced duration of the fluid dynamic evolution or when less fraction of the medium undergoes the transition. These effects are due to the limitations of the underlying physics and the DL models are shown to be superior in its discrimination performance in comparison to conventional mean observables.

   ↳ hep-phnucl-exnucl-thJHEP(2021)·32 citations
9. 09*

   Study of radial motion phase advance during motion excitations in a Penning trap and accuracy of JYFLTRAP mass spectrometer

   D.A. Nesterenko🇫🇮 · T. Eronen🇫🇮 · Z. Ge🇫🇮 · A. Kankainen🇫🇮 · M. Vilen🇫🇮

   Phase-imaging ion-cyclotron-resonance technique has been implemented at the Penning-trap mass spectrometer JYFLTRAP and is routinely employed for mass measurements of stable and short-lived nuclides produced at IGISOL facility. Systematic uncertainties that impose limitations on the accuracy of measurements are discussed. It was found out that the phase evolution of the radial motion of ions in a Penning trap during the application of radio-frequency fields leads to a systematic cyclotron frequency shift when more than one ion species is present in the trap during the cyclotron frequency measurement. An analytic expression was derived to correctly account for the shift. Cross-reference mass measurements with carbon-cluster ions have been performed providing the mass-dependent and residual uncertainties.

   ↳ physics.ins-detnucl-exEPJA(2021)·50 citations
10. 10*

    Constraints on Gluon Distribution Functions in the Nucleon and Nucleus from Open Charm Hadron Production at the Electron-Ion Collider

    Matthew Kelsey🇺🇸 · Reynier Cruz-Torres🇺🇸 · Xin Dong🇺🇸 · Yuanjing Ji🇺🇸 · Sooraj Radhakrishnan🇺🇸 · Ernst Sichtermann🇺🇸

    The Electron-Ion Collider (EIC) at Brookhaven National Laboratory will be a precision Quantum Chromodynamics machine that will enable a vast physics program with electron+proton/ion collisions across a broad center-of-mass range. Measurements of hard probes such as heavy flavor in deep inelastic scatterings will be an essential component to the EIC physics program and are one of the detector R\&D driving aspects. In this paper we study the projected statistical precision of open charm hadron production through exclusive hadronic channel reconstruction with a silicon detector concept currently being developed using a PYTHIA-based simulation. We further study the impact of possible intrinsic charm in the proton on projected data, and estimate the constraint on the nuclear gluon parton distribution function (PDF) from the charm structure functions $F_2^{c\overline{c}}$ in $e$+Au collisions using a Bayesian PDF re-weighting technique. Our studies show the EIC will be capable delivering an unprecedented measurement of charm hadron production across a broad kinematic region and will provide strong constraints to both intrinsic charm and nuclear gluon PDFs.

    ↳ hep-phhep-exnucl-exPRD(2021)·17 citations
11. 11*

    Matrix Model: Emergence of a Quantum Number in the Strong Coupling Regime

    Castaly Fan · Larry Zamick🇺🇸

    We continue here to study simple matrix models of quantum mechanical Hamiltonians. The eigenvalues and eigenfunctions were associated energy levels and wave functions. Whereas previously we considered the weak coupling limits of our models, we here address the more difficult strong coupling limits. We find that the wave functions fall into 2 classes and we can assign a quantum number to distinguish them. Implications for transition rates are also discussed.

    ↳ nucl-thnucl-exIJMPE(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.