Nuclear Theory·nucl-th

Monday·April 22, 2024

14 papers—4 primary·10 cross-listed

01
Study of the electromagnetic form factors of the nucleons in the timelike region
Qin-He Yang🇨🇳 · Di Guo🇨🇳 · Ming-Yan Li🇨🇳 · Ling-Yun Dai🇨🇳 · Johann Haidenbauer🇩🇪 · Ulf-G. Meißner🇩🇪
The electromagnetic form factors $G_{E}$ and $G_{M}$ of the proton and neutron in the timelike region are extracted in a study of the processes $e^{+} e^{-} \to p ˉ p$ and $e^{+} e^{-} \to n ˉ n$ . The reaction amplitude is evaluated within the distorted wave Born approximation, with the interaction of the antinucleon-nucleon ( $N ˉ N$ ) pair taken into account. The latter is constructed within $S U (3)$ chiral effective field theory up to the next-to-leading order. An excellent description of the $e^{+} e^{-} \to N ˉ N$ data in the energy region from the $N ˉ N$ threshold up to center-of-mass energies $E_{cm} = 2.2$ ~GeV is achieved. Results for the electromagnetic form factors $G_{E}, G_{M}$ , $G_{E} / G_{M}$ , and the subtracted effective form factors, $G_{osc}$ , are provided. These can be helpful for further studies of the properties of the nucleons.
nucl-thhep-phJHEP(2024)·8 citations
02
Nuclear charge radius predictions by kernel ridge regression with odd-even effects
Lu Tang · Zhen-Hua Zhang
The extended kernel ridge regression (EKRR) method with odd-even effects was adopted to improve the description of the nuclear charge radius using five commonly used nuclear models. These are: (i) the isospin dependent $A^{1/3}$ formula, (ii) relativistic continuum Hartree-Bogoliubov (RCHB) theory, (iii) Hartree-Fock-Bogoliubov (HFB) model HFB25, (iv) the Weizsäcker-Skyrme (WS) model WS $^{*}$ , and (v) HFB25 $^{*}$ model. In the last two models, the charge radii were calculated using a five-parameter formula with the nuclear shell corrections and deformations obtained from the WS and HFB25 models, respectively. For each model, the resultant root-mean-square deviation for the 1014 nuclei with proton number $Z \geq 8$ can be significantly reduced to 0.009-0.013~fm after considering the modification with the EKRR method. The best among them was the RCHB model, with a root-mean-square deviation of 0.0092~fm. The extrapolation abilities of the KRR and EKRR methods for the neutron-rich region were examined and it was found that after considering the odd-even effects, the extrapolation power was improved compared with that of the original KRR method. The strong odd-even staggering of nuclear charge radii of Ca and Cu isotopes and the abrupt kinks across the neutron $N = 126$ and 82 shell closures were also calculated and could be reproduced quite well by calculations using the EKRR method.
nucl-thnucl-exNucl.Sci.Tech.(2024)·28 citations
03
Nucleon microscopy in proton-nucleus scattering via analysis of bremsstrahlung emission: role of incoherent emission
Sergei P. Maydanyuk (1,2,4)🇨🇳 · Li-Ping Zou (2)🇨🇳 · Peng-Ming Zhang (3) ((1) Sino-French Institute of Nuclear Engineering and Technology, Sun Yat-Sen University, Zhuhai, China, (2) Wigner Research Centre for Physics, Budapest, Hungary, (3) School of Physics and Astronomy, Sun Yat-Sen University, Zhuhai, China, (4) Institute for Nuclear Research, National Academy of Sciences of Ukraine, Kyiv, Ukraine)🇨🇳
We study electromagnetic form factors of protons in proton-nucleus scattering via analysing of experimental cross-sections of accompanying bremsstrahlung photons. A new bremsstrahlung model for proton-nucleus scattering is developed, where a main focus is given on incoherent bremsstrahlung that has not been considered previously. In analysis we choose experimental bremsstrahlung data of $p$ + $^{197}$ Au scattering at proton beam energy of 190 MeV obtained by TAPS collaboration. We find the following. (1) Inclusion of incoherent emission to calculations improves agreements with experimental data essentially, contribution of incoherent bremsstrahlung is essentially larger than coherent one. (2) Inclusion of form factors of the scattered proton improves agreement with experimental data in comparison with calculations with coherent and incoherent contributions without form factors. (3) Sensitivity of model in study of form factors of the scattered proton is high. This demonstrates a new opportunity to study internal structure of protons under influence of nuclear forces in nuclear scattering.
nucl-thhep-phPRC(2025)·0 citations
04
Hypernuclear constraints on the existence and lifetime of a deeply bound $H$ dibaryon
Avraham Gal🇮🇱
We study to what extent the unique observation of $ΛΛ$ hypernuclei by their weak decay into known $Λ$ hypernuclei, with lifetimes of order 10 $^{- 10}$ s, rules out the existence of a deeply bound doubly-strange ( $S$ = $-$ 2) $H$ dibaryon. Treating $_{ΛΛ}^{6} He$ (the Nagara emulsion event) in a realistic $Λ - Λ -^{4}$ He three-body model, we find that the $_{ΛΛ}^{6} He \to H +^{4} He$ strong-interaction lifetime increases beyond 10 $^{- 10}$ s for $m_{H} < m_{Λ} + m_{n}$ , about 176 MeV below the $ΛΛ$ threshold, so that such a deeply bound $H$ is not in conflict with hypernuclear data. Constrained by $Λ$ hypernuclear $Δ S$ =1 nonmesonic weak-interaction decay rates, we follow EFT methods to evaluate the $Δ S$ =2 $H \to nn$ weak-decay lifetime of $H$ in the mass range $2 m_{n} ≲ m_{H} < m_{Λ} + m_{n}$ . The resulting $H$ lifetime is of order 10 $^{5}$ s, many orders of magnitude shorter than required to qualify for a dark-matter candidate.
nucl-thhep-phnucl-exPLB(2024)·13 citations
05
Strange quark matter as dark matter: 40 years later, a reappraisal
Francesco Di Clemente🇮🇹 · Marco Casolino🇮🇹 · Alessandro Drago🇮🇹 · Massimiliano Lattanzi🇮🇹 · Claudia Ratti🇺🇸
Forty years ago Witten suggested that dark matter could be composed of macroscopic clusters of strange quark matter. This idea was very popular for several years, but it dropped out of fashion once lattice QCD calculations indicated that the confinement/deconfinement transition, at small baryonic chemical potential, is not first order, which seemed to be a crucial requirement in order to produce large clusters of quarks. Here we revisit the conditions under which strangelets can be produced in the Early Universe. We discuss the impact of an instability in the hadronic phase separating a low density, positive-strange-charge phase from a high-density phase with a negative strange charge. This second phase can rapidly stabilize by forming color-superconducting gaps. The strangelets then undergo partial evaporation. In this way, we obtain distributions of their sizes in agreement with the observational constraints and we discuss the many astrophysical and cosmological implications of these objects. Finally, we examine the most promising techniques to detect this type of strangelets. We also show that strangelets can exist with masses $≲ 1 0^{17} g$ , while primordial black holes are ruled out in that mass range, allowing us to distinguish between these two dark matter candidates.
↳ hep-phastro-ph.COnucl-thMNRAS(2025)·15 citations
06
Analysis of QCD at finite isospin density: on the relationship between quark degrees of freedom in hadrons and equation of state
Ryuji Chiba🇯🇵
We investigate the quark contribution to the equation of state (EOS) of the isospin QCD matter using the two-flavor quark meson model at finite isospin density. This model includes the quark degrees of freedom through the lowest order of the loop correction. This model describes the crossover of the pion condensate from the Bose-Einstein condensation (BEC) phase at low density to the Bardeen-Cooper-Schrieffer (BCS) phase at high density. In the absence of the quark degrees of freedom the pion condensate behaves as the bosonic object, but the quark substructure becomes important and suppress the pion condensate by Pauli blocking as density increase. As the isospin density increases, the EOS rapidly becomes stiff and approaches to the quark matter even before pion starts to overlap. Consequently, the sound velocity exceeds the conformal value $c_{s}^{2} = 1/3$ , forming a peak structure and then relax to the conformal value from above at high density. This is in good agreement with the recent lattice QCD (LQCD) result. In contrast, the perturbative QCD (pQCD) result suggests that the sound velocity approaches to the conformal value from below. This discrepancy comes from the non-perturbative effects arising from the pion condensate or the quark-antiquark correlation near the Fermi surface in the quark meson model. We also investigated the trace anomaly as another measure of conformality. The effects of finite temperature on sound velocity were also examined. On the isentropic trajectory, where $s / n_{I}$ is fixed, the thermal quarks were found to suppress the sound velocity and smear out the peak structure. The thermal mesons are considered to be important at zero density from LQCD, which is confirmed in this model calculation. The analysis is further extended to the condensed phase at high density, where it is found that thermal mesons do not significantly contribute to the EOS.
↳ hep-phnucl-th0 citations
07
Exact unified tetraquark equations
B. Blankleider🇦🇺 · A. N. Kvinikhidze🇦🇺
Recently we formulated covariant equations describing the tetraquark in terms of an admixture of two-body states $D D ˉ$ (diquark-antidiquark), $M M$ (meson-meson), and three-body-like states where two of the quarks are spectators while the other two are interacting [Phys. Rev. D 107, 094014 (2023)]. A feature of these equations is that they unify descriptions of seemingly unrelated models of the tetraquark, like, for example, the $D D ˉ$ model of the Moscow group [Faustov et al., Universe 7, 94 (2021)] and the coupled channel $D D ˉ - M M$ model of the Giessen group [Heupel et al., Phys. Lett. B718, 545 (2012)]. Here we extend these equations to the exact case where $q q ˉ$ annihilation is incorporated explicitly, and all previously neglected terms (three-body forces, non-pole contributions to two-quark t matrices, etc.) are taken into account through the inclusion of a single $q q ˉ$ potential $Δ$ .
↳ hep-phnucl-thFew Body Syst.(2024)·2 citations
08
Constraints on extra dimensions theories from gravitational quantum barrier experiments
J. M. Rocha🇧🇷 · F. Dahia🇧🇷
We discuss the quantum-bouncer experiment involving ultracold neutrons in a braneworld scenario. Extra-dimensional theories typically predict the strengthening of gravitational interactions over short distances. In this paper, we specifically study the anomalous gravitational interaction between the bouncing neutron and the reflecting mirror, resulting from hidden dimensions, and its effect on the outcome of this experiment in the context of a thickbrane model. This analysis allows us to identify which physical quantity of this extra-dimensional theory this neutron experiment is capable of constraining. Based on the experimental data, we found a new and independent empirical bound on free parameters of the model: the higher-dimensional gravitational constant and a parameter related to a transverse width of the confined matter inside the thickbrane. This new bound is valid in scenarios with an arbitrary number of extra dimensions greater than two. In this manner, by considering the thickness of the brane, we have been able to extend previous studies on this topic, which were limited to models with few codimensions, due to non-computability problems of power-law corrections of the gravitational potential.
↳ gr-qchep-phnucl-thquant-phClass.Quant.Grav.(2024)·2 citations
09
Study of bottom quark dynamics via non-prompt $D^{0}$ and $J / ψ$ in Pb+Pb collisions at $s_{NN} = 5.02$ TeV
Wen-Jing Xing🇨🇳 · Shu-Qing Li🇨🇳 · Shanshan Cao🇨🇳 · Guang-You Qin🇨🇳
We study bottom quark energy loss via the nuclear modification factor ( $R_{AA}$ ) and elliptic flow ( $v_{2}$ ) of non-prompt $D^{0}$ and $J / ψ$ in relativistic heavy-ion collisions at the LHC. The space-time profile of quark-gluon plasma is obtained from the CLVisc hydrodynamics simulation, the dynamical evolution of heavy quarks inside the color deconfined QCD medium is simulated using a linear Boltzmann transport model that combines Yukawa and string potentials of heavy-quark-medium interactions, the hadronization of heavy quarks is performed using a hybrid coalescence-fragmentation model, and the decay of $B$ mesons is simulated via PYTHIA. Using this numerical framework, we calculate the transverse momentum ( $p_{T}$ ) dependent $R_{AA}$ and $v_{2}$ of direct $D$ mesons, $B$ mesons, and non-prompt $D^{0}$ and $J / ψ$ from $B$ meson decay in Pb+Pb collisions at $s_{NN} = 5.02$ TeV. We find the mass hierarchy of the nuclear modification of prompt $D$ and $B$ mesons depends on their $p_{T}$ . Both $R_{AA}$ and $v_{2}$ of heavy flavor particles show strong $p_{T}$ and centrality dependences due to the interplay between parton energy loss, medium geometry and flow, and hadronization of heavy quarks. Non-prompt $D^{0}$ and $J / ψ$ share similar patterns of $R_{AA}$ and $v_{2}$ to $B$ mesons except for a $p_{T}$ shift during the decay processes. Therefore, future more precise measurements on non-prompt $D^{0}$ and $J / ψ$ can help further pin down the bottom quark dynamics inside the quark-gluon plasma.
↳ hep-phnucl-exnucl-thPRC(2024)·9 citations
10
The MONUMENT Experiment: Ordinary Muon Capture studies for 0 $ν β β$ decay
Dhanurdhar Bajpai🇨🇭 · Laura Baudis🇺🇸 · Viacheslav Belov🇨🇭 · Elisabetta Bossio🇷🇺 · Thomas E. Cocolios🇩🇪 · Hiroyasu Ejiri🇧🇪 · Evgenii Sushenok🇯🇵 · Maria Fomina🇷🇺 · Izyan H. Hashim🇷🇺 · Michael Heines🇲🇾 · Konstantin Gusev🇧🇪 · Sergej Kazartsev🇷🇺 and 17 other authors
The MONUMENT experiment measures ordinary muon capture (OMC) on isotopes relevant for neutrinoless double-beta (0 $ν β β$ ) decay and nuclear astrophysics. OMC is a particularly attractive tool for improving the theoretical description of 0 $ν β β$ decay. It involves similar momentum transfers and allows testing the virtual transitions involved in 0 $ν β β$ decay against experimental data. During the 2021 campaign, MONUMENT measured OMC on $^{76}$ Se and $^{136}$ Ba, the isotopes relevant for next-generation 0 $ν β β$ decay searches, like LEGEND and nEXO. The experimental setup has been designed to accurately extract the total and partial muon capture rates, which requires precise reconstruction of energies and time-dependent intensities of the OMC-related $γ$ rays. The setup also includes a veto counter system to allow selecting a clean sample of OMC events. This work provides a detailed description of the MONUMENT setup operated during the 2021 campaign, its two DAQ systems, calibration and analysis approaches, and summarises the achieved detector performance. Future improvements are also discussed.
↳ nucl-exnucl-thEPJC(2024)·12 citations
11
Comprehensive study of compact stars with dark matter
Mikel F. Barbat🇪🇸 · Jürgen Schaffner-Bielich🇩🇪 · Laura Tolos🇩🇪
We present a comprehensive study of compact stars admixed with non-self annihilating self-interacting fermionic dark matter, delineating the dependence on the nuclear equation of state by considering the two limiting parametrized equations of state for neutron star matter obtained by smoothly matching the low-density chiral effective theory and the high-density perturbative QCD. These two parametrizations are the limiting cases of a wide variety of smooth equations of state, i.e. the softest and stiffest possible one without a phase transition, that generate masses and radii compatible with 2M $_{⊙}$ observations and the tidal constraint from GW170817. With an exhaustive analysis of the possible stable mass-radius configurations, we determine the quantity of dark matter contained in stars with masses and radii compatible with the aforementioned astrophysical constraints. We find that for dark particle masses of a few tenths of GeV, the dark core collapses and no stable solutions are found for the two limiting ordinary matter equations of state. For lower masses, the dark matter fraction is limited to 10%, being at most 1% for masses ranging from 0.1 to 10 GeV for the limiting soft nuclear equation of state. For the limiting stiff nuclear equation of state, the dark matter fraction can reach values of more than 10%, but the dark particle mass is being constrained to 0.3 GeV and 10 GeV for the weak self-interacting case and has to be at least 5 GeV for the strong self-interacting one. For dark particle masses of less than 0.1 GeV, stable neutron star configurations should have less than 1% of self-interacting dark matter to be compatible with the constraint of the tidal deformability from GW170817 for the two limiting ordinary matter equations of state studied.
↳ astro-ph.HEnucl-thPRD(2024)·59 citations
12
Hydrodynamic Attractor in Ultracold Atoms
Keisuke Fujii · Tilman Enss
The hydrodynamic attractor is a concept that describes universal equilibration behavior in which systems lose microscopic details before hydrodynamics becomes applicable. We propose a setup to observe hydrodynamic attractors in ultracold atomic gases, taking advantage of the fact that driving the two-body $s$ -wave scattering length causes phenomena equivalent to isotropic fluid expansions. We specifically consider two-component fermions with contact interactions in three dimensions and discuss their dynamics under a power-law drive of the scattering length in a uniform system. By explicit computation, we derive a hydrodynamic relaxation model. We analytically solve their dynamics and find the hydrodynamic attractor solution. Our proposed method using the scattering length drive is applicable to a wide range of ultracold atomic systems, and our results establish these as a new platform for exploring hydrodynamic attractors.
↳ cond-mat.quant-gashep-phhep-thnucl-thPRL(2024)·15 citations
13
Non-extensive statistics in Au-Au collisions
Juliana O. Costa🇧🇷 · Isabelle Aguiar🇧🇷 · Jadna L. Barauna🇧🇷 · Eugenio Megías🇪🇸 · Airton Deppman🇧🇷 · Tiago N. da Silva🇧🇷 · Débora P. Menezes🇧🇷
Particle production yields measured in central Au-Au collision at RHIC are obtained with free Fermi and Bose gases and also with a replacement of these statistics by non-extensive statistics. For the latter calculation, a set of different parameters was used with values of the Tsallis parameter $q$ chosen between 1.01 and 1.25, with 1.16 generating the best agreement with experimental data, an indication that non-extensive statistics may be one of the underlying features in heavy ion-collisions.
↳ hep-phnucl-thPLB(2024)·7 citations
14
Photoexcitation of the $^{229}$ Th nuclear clock transition using twisted light
Tobias Kirschbaum · Thorsten Schumm · Adriana Pálffy
The $^{229}$ Th nucleus has a unique transition at only 8 eV which could be used for a novel nuclear clock. We investigate theoretically the prospects of driving this transition with vortex light beams carrying orbital angular momentum. Numerical results are presented for two experimental configurations which are promising for the design of the planned nuclear clock: a trapped ion setup and a large ensemble of nuclei doped into CaF $_{2}$ crystals which are transparent in the frequency range of the nuclear transition. We discuss the feasibility of the vortex beam nuclear excitation and compare the excitation features with the case of plane wave beams.
↳ physics.atom-phnucl-thPRC(2024)·13 citations

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