Nuclear Theory·nucl-th

Friday·August 26, 2022

9 papers—6 primary·3 cross-listed

01
[Submitted on 25 Aug 2022]
Midrapidity cluster formation in heavy-ion collisions
Elena Bratkovskaya🇩🇪 · Susanne Glässel🇩🇪 · Viktar Kireyeu🇩🇪 · Jörg Aichelin🇫🇷 · Marcus Bleicher🇩🇪 · Christoph Blume🇩🇪 · Gabriele Coci🇩🇪 · Vadim Kolesnikov🇷🇺 · Jan Steinheimer🇩🇪 · Vadim Voronyuk🇩🇪
We study the production of clusters and hypernuclei at midrapidity employing the Parton-Hadron-Quantum-Molecular-Dynamics (PHQMD) approach, a microscopic n-body transport model based on the QMD propagation of the baryonic degrees of freedom with density dependent 2-body potential interactions. In PHQMD the cluster formation occurs dynamically, caused by the interactions. The clusters are recognized by the Minimum Spanning Tree (MST) algorithm. We present the PHQMD results for cluster and hypernuclei formation in comparison with the available experimental data at relativistic energies. PHQMD allows to study the time evolution of formed clusters and the origin of their production, which helps to understand how such weakly bound objects are formed and survive in the rather dense and hot environment created in heavy-ion collisions. It offers therefore an explanation of the 'ice in the fire' puzzle. To investigate whether this explanation of the 'ice in the fire' puzzle applies only to the MST results we study also the deuterons production by coalescence. We embed MST and coalescence in the PHQMD and UrQMD transport approaches in order to obtain model independent results. We find that both clustering procedures give very similar results for the deuteron observables in the UrQMD as well as in the PHQMD environment. This confirms that our solution for the 'ice in the fire' puzzle is common to MST and coalescence and independent of the transport approach.
Comments:
6 pages, 6 figures, Contribution to the SQM-2022 Proceedings
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2208.11802 [pdf]
EPJ Web Conf.(2023)·12 citations
02
[Submitted on 25 Aug 2022]
A tensor decomposition model for evaluating isotopic yield in neutron-induced fission
Qufei Song · Long Zhu · Jun Su · Hui Guo
After constructing yield tensors with three dimensions for 851 fission products and filling the tensors with the independent yield data from the ENDF/B-VIII.0 database, the tensor decomposition algorithm is applied to predict the independent isotopic yield in fission, which resulting in the Fission Yield Tensor Decomposition (FYTD) model. The fission yields of 235U and 239Pu are set as missing values and then predicted. The predictions for235U fissions by the FYTD model agree with the ENDF/B-VIII.0 data and are better than those by the Talys and BNN+Talys models. Furthermore, we predict not only the mass distribution but also the isotopic yields in the fissions. For fast neutron-induced fission of 239Pu, 98% predictions of the isotopic yields by the FYTD model agree with the ENDF/B-VIII.0 data within 1 order of magnitude. The fission yields of 238Np, 243Am, and 236Np that do not exist in the ENDF/B-VIII.0 database are predicted and compared with those in the JEFF-3.3 database, as well as the experimental data. Good agreement demonstrates the predictive ability of the FYTD model for the target nucleus dependence. The scalability of the yield tensor decomposition model over the incident neutron energy degrees of freedom is examined. After adding a set of 2 MeV neutron-induced 239Pu fission yield data into the yield tensor, the 2 MeV neutron-induced fission yields of 235U and 239Pu are predicted. The comparison with the experimental data shows that the predictions are similar to those by the GEF model in the peak area but more accurate in the valley area. Finally, the yields of the ratio of isomeric states and neutron excess of the products as a function of product charge number are also studied. The FYTD model can capture the multi-dimensional dependence of the fission yield data and make reasonable predictions.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2208.11815 [pdf]
1 citation
03
[Submitted on 25 Aug 2022]
Sensitivity of Au+Au collisions to the symmetric nuclear matter equation of state at 2 -- 5 nuclear saturation densities
Dmytro Oliinychenko🇺🇸 · Agnieszka Sorensen🇺🇸 · Volker Koch🇺🇸 · Larry McLerran🇺🇸
We demonstrate that proton and pion flow measurements in heavy-ion collisions at incident energies ranging from 1 to 20 GeV per nucleon in the fixed target frame can be used for an accurate determination of the symmetric nuclear matter equation of state at baryon densities equal 2--4 times nuclear saturation density $n_{0}$ . We simulate Au+Au collisions at these energies using a hadronic transport model with an adjustable vector mean-field potential dependent on baryon density $n_{B}$ . We show that the mean field can be parametrized to reproduce a given density-dependence of the speed of sound at zero temperature $c_{s}^{2} (n_{B}, T = 0)$ , which we vary independently in multiple density intervals to probe the differential sensitivity of heavy-ion observables to the equation of state at these specific densities. Recent flow data from the STAR experiment at the center-of-mass energies $s_{N N} = {3.0, 4.5}$ GeV can be described by our model, and a Bayesian analysis of these data indicates a hard equation of state at $n_{B} \in (2, 3) n_{0}$ and a possible phase transition at $n_{B} \in (3, 4) n_{0}$ . More data at $s_{N N} = 2 - 5$ GeV, as well as a more thorough analysis of the model systematic uncertainties will be necessary for a more precise conclusion.
Comments:
26 pages, 18 figures, accepted to publication in Phys Rev C, minor fixes
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2208.11996 [pdf]
PRC(2023)·81 citations
04
[Submitted on 25 Aug 2022]
The high-density equation of state in heavy-ion collisions: Constraints from proton flow
Jan Steinheimer🇩🇪 · Anton Motornenko🇩🇪 · Agnieszka Sorensen🇺🇸 · Yasushi Nara🇯🇵 · Volker Koch🇺🇸 · Marcus Bleicher🇩🇪
A set of different equations of state is implemented in the molecular dynamics part of a non-equilibrium transport simulation (UrQMD) of heavy-ion collisions. It is shown how different flow observables are affected by the density dependence of the equation of state. In particular, the effects of a phase transition at high density are explored, including an expected reduction in mean $m_{T}$ . We also show that an increase in $v_{2}$ is characteristic for a strong softening of the equation of state. The phase transitions with a low coexistence density, $n_{CE} < 4 n_{0}$ , show a distinct minimum in the slope of the directed flow as a function of the beam energy, which would be a clear experimental signal. By comparing our results with experimental data, we can exclude any strong phase transition at densities below $4 n_{0}$ .
Comments:
12 pages, 5 figures, version accepted for publication
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2208.12091 [pdf]
EPJC(2022)·56 citations
05
[Submitted on 25 Aug 2022]
Production of neutron-rich actinide nuclides in isobaric collisions via multinucleon transfer reactions
Peng-Hui Chen · Chang geng · Hao Wu · Xiang-Hua Zeng · Zhao-Qing Feng
We have calculated the multinucleon transfer reactions of $^{208}$ Os, $^{208}$ Pt, $^{208}$ Hg, $^{208}$ Pb, $^{208}$ Po, $^{208}$ Rn, $^{208}$ Ra, $^{132, 136}$ Xe bombarding on $^{232}$ Th and $^{248}$ Cm at Coulomb barrier energies within the dinuclear system model, systematically. The results are in good agreement with the available experimental data. Coulomb effect and shell effect on production of actinides in these reactions have been investigated thoroughly. Potential energy surface and total kinetic energy mass distributions in the reactions $^{208}$ Hg, $^{208}$ Pb and $^{208}$ Po colliding on $^{248}$ Cm and $^{232}$ Th are calculated and analyzed, respectively. It is found that PES and TKE spectra manifest the fragment formation mechanism in the multinucleon transfer reactions. The isospin effect and shell effect are shown in PES and TKE. Production cross-sections of multinucleon transfer products are highly dependent on the isobar projectiles with mass number $A = 208$ . The isobar projectiles with larger N/Z ratios are favorable for creating the neutron-rich target-like fragments. The isobar projectiles with larger charge number induced products tend to shift to proton-rich region. Coulomb potential coupled to shell effect is shown in production cross-sections of actinide isotopes. Based on the radioactive projectiles induced reactions, we have predicted massive new actinide isotopes around nuclear drip lines, even could access the superheavy nuclei region.
Comments:
10 pages, 8 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2208.12107 [pdf]
Nucl.Sci.Tech.(2023)·12 citations
06
[Submitted on 25 Aug 2022]
Multiplicity fluctuations and correlations in 5.02 TeV p+Pb collisions at zero impact parameter
Mathis Pepin🇫🇷 · Peter Christiansen🇸🇪 · Stéphane Munier🇫🇷 · Jean-Yves Ollitrault🇫🇷
We present a Bayesian method to reconstruct event-by-event multiplicity fluctuations and rapidity correlations in p+Pb collisions at zero impact parameter from minimum-bias data, without assuming any model of the collision dynamics. We test it on Monte Carlo simulations with the Angantyr model, then apply it to ATLAS data on the distribution of charged multiplicity and transverse energy in p+Pb collisions at $s_{NN} = 5.02$ TeV. Fluctuations in $b = 0$ collisions are quantum fluctuations which originate mostly from the proton wave function, and therefore have the potential to constrain the subnucleonic structure of the proton. The Angantyr model is found to overestimate fluctuations. In addition, we find that as the rapidity increases (towards the Pb-going side), not only the multiplicity density increases, but also its relative event-by-event fluctuation. This counter-intuitive phenomenon is also observed in simulations with Angantyr, and with the QCD dipole model, where its origin can be traced back to the branching process through which gluons are produced.
Comments:
15 pages, 10 figures. v2: revised. Discussion of the fluctuating string model and of forward-backward correlations added in Sec.IVC and IVD. The Python code used to fit minimum-bias data (described in Sec. IIIB) is added as an ancillary file
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2208.12175 [pdf]
PRC(2023)·7 citations
07
[Submitted on 24 Aug 2022] (cross-list from hep-ph)
Scrutinizing CKM unitarity with a new measurement of the $K_{μ 3} / K_{μ 2}$ branching fraction
Vincenzo Cirigliano🇺🇸 · Andreas Crivellin🇨🇭 · Martin Hoferichter🇨🇭 · Matthew Moulson🇨🇭
Precision tests of first-row unitarity of the Cabibbo-Kobayashi-Maskawa matrix currently display two intriguing tensions, both at the $3 σ$ level. First, combining determinations of $V_{u d}$ from superallowed $β$ decays with $V_{u s}$ from kaon decays suggests a deficit in the unitarity relation. At the same time, a tension of similar significance has emerged between $K_{ℓ 2}$ and $K_{ℓ 3}$ decays. In this Letter, we point out that a measurement of the $K_{μ 3} / K_{μ 2}$ branching fraction at the level of $0.2%$ would have considerable impact on clarifying the experimental situation in the kaon sector, especially in view of tensions in the global fit to kaon data as well as the fact that the $K_{μ 2}$ channel is currently dominated by a single experiment. Such a measurement, as possible for example at NA62, would further provide important constraints on physics beyond the Standard Model, most notably on the role of right-handed vector currents.
Comments:
8 pages, 2 figures; journal version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2208.11707 [pdf]
PLB(2023)·115 citations
08
[Submitted on 24 Aug 2022] (cross-list from hep-lat)
How many quantum gates do gauge theories require?
Edison M. Murairi🇺🇸 · Michael J. Cervia🇺🇸 · Hersh Kumar🇺🇸 · Paulo F. Bedaque🇺🇸 · Andrei Alexandru🇺🇸
We discuss the implementation of lattice gauge theories on digital quantum computers, focusing primarily on the number of quantum gates required to simulate their time evolution. We find that to compile quantum circuits, using available state-of-the-art methods with our own augmentations, the cost of a single time step of an elementary plaquette is beyond what is reasonably practical in the current era of quantum hardware. However, we observe that such costs are highly sensitive to the truncation scheme used to derive different Hamiltonian formulations of non-Abelian gauge theories, emphasizing the need for low-dimensional truncations of such models in the same universality class as the desired theories.
Comments:
14 pages of RevTeX, 7 figures
Subjects:
High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2208.11789 [pdf]
PRD(2022)·45 citations
09
[Submitted on 25 Aug 2022] (cross-list from hep-ph)
Pole determination of $P_{ψ s}^{Λ} (4338)$ and possible $P_{ψ s}^{Λ} (4255)$ in $B^{-} \to J / ψ Λ p ˉ$
S.X. Nakamura (Univ. of Science and Technology of China)🇨🇳 · J.-J. Wu (Univ. of Chinese Academy of Sciences)🇨🇳
First hidden-charm pentaquark candidate with strangeness, $P_{ψ s}^{Λ} (4338)$ , was recently discovered in $B^{-} \to J / ψ Λ p ˉ$ by the LHCb Collaboration. $P_{ψ s}^{Λ} (4338)$ shows up as a bump at the $Ξ_{c} D ˉ$ threshold in the $J / ψ Λ$ invariant mass ( $M_{J / ψ Λ}$ ) distribution. The $M_{J / ψ Λ}$ distribution also shows a large fluctuation at the $Λ_{c} D ˉ_{s}$ threshold, hinting the existence of a possible $P_{ψ s}^{Λ} (4255)$ . In this work, we determine the $P_{ψ s}^{Λ} (4338)$ and $P_{ψ s}^{Λ} (4255)$ pole positions for the first time. For this purpose, we fit a $B^{-} \to J / ψ Λ p ˉ$ model to the $M_{J / ψ Λ}$ , $M_{J / ψ p ˉ}$ , $M_{Λ p ˉ}$ , and $cos θ_{K^{*}}$ distributions from the LHCb simultaneously; $χ^{2} / ndf \sim 1.21$ . Then we extract $P_{ψ s}^{Λ}$ poles from a unitary $Ξ_{c} D ˉ$ - $Λ_{c} D ˉ_{s}$ coupled-channel scattering amplitude built in the model. In our default fit, the $P_{ψ s}^{Λ} (4338)$ pole is found at $(4338.2 \pm 1.4) - (1.9 \pm 0.5) i$ MeV while the $P_{ψ s}^{Λ} (4255)$ pole at $4254.7 \pm 0.4$ MeV. The $P_{ψ s}^{Λ} (4338)$ and $P_{ψ s}^{Λ} (4255)$ are mostly $Ξ_{c} D ˉ$ bound and $Λ_{c} D ˉ_{s}$ virtual states, respectively. Through our analysis, the data disfavors a hypothesis of $P_{ψ s}^{Λ} (4338)$ as merely a kinematical effect. This pole determination, which is important in its own right, sets a primary basis to study the nature of the $P_{ψ s}^{Λ}$ states.
Comments:
8 pages, 5 figures, 3 tables; (v2) statistical errors of pole values corrected; (v3) efficiency-corrected and background-subtracted data are analyzed; a figure of Dalitz plot distribution added; (v4) published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2208.11995 [pdf]
PRD(2023)·48 citations

Affiliations

first authorsco-authorsvia INSPIRE