Nuclear Theory·nucl-th

Thursday·May 16, 2024

12 papers—4 primary·8 cross-listed

01
Determination of pairing matrix elements from average single particle level densities
Meng-Hock Koh🇲🇾 · Philippe Quentin🇫🇷
A simple and efficient method to treat nuclear pairing correlations within a simple Hartree-Fock--plus-BCS description is proposed and discussed. It relies on the fact that the intensity of pairing correlations depends crucially on level densities around the Fermi surface ( $ρ (e_{F})$ ) and that any fitting of nuclear energies as functions of the nucleon numbers is akin of a semi-classical average, smoothing out their quantal structure. A particular attention has been paid to two points generally ignored in previous similar approaches. One is a correction advocated by Möller and Nix [Nucl. Phys. A 536, 20 (1992)] taking into account the fact that the data included into the fit correspond to $ρ (e_{F})$ values systematically lower than average. The second is due to a systematic overestimation of the proton sp level density at the Fermi surface resulting from the local Slater approximation of the Coulomb terms in use in most microscopic descriptions. Our approach is validated by the agreement with data of corresponding calculated moments of inertia of well and rigidly deformed rare-earth nuclei, evaluated according to the Inglis-Belyaev ansatz with some crude Thouless-Valatin corrections. Indeed, the agreement which is found, is at least of the same quality as what results from a specific fit of the pairing intensities to these particular pieces of data. While this approach is currently limited to the very simple seniority force pairing treatment, it may serve as a starting point to define pairing residual interactions from averaged odd-even mass differences data, using merely average sp level densities associated to calculated canonical basis.
nucl-thPRC(2024)·3 citations
02
Microscopic Investigation of Ground State Properties and Shape Evolution in Osmium Isotopes
Usuf Rahaman · M.Ikram · Ishfaq A. Rather · Anisul Ain Usmani
The present study focuses on investigating the shape evolution of neutron-rich even-even Osmium (Os) transitional nuclei within the range of neutron number N = 82 to N = 190. The investigation is conducted using density-dependent meson-nucleon and point-coupling models within the framework of the covariant density functional theory (CDFT). Additionally, the results obtained from the CDFT calculations are compared with those obtained using the relativistic mean-field model with a non-linear meson-nucleon interaction. The potential energy curve for Os isotopes (ranging from $^{158}$ Os to $^{260}$ Os) is analyzed in order to identify phase shape transitions, such as oblate-spherical-prolate. Furthermore, ground state bulk properties are calculated to gain insights into the structure of Os isotopes. The self-consistent calculations reveal a clear shape transition in the even-even Os isotopes, and overall, good agreement is observed among the different models employed as well as with the available experimental data.
nucl-thBraz.J.Phys.(2024)·1 citation
03
Theoretical analysis of the reactions induced by interaction of $^{6}$ Li with nuclei $^{3}$ H and $^{3}$ He
Yu. A. Lashko · V. S. Vasilevsky · V. I. Zhaba
We determine cross sections and astrophysical S-factors of the reactions generated in collisions between $^{6}$ Li and $^{3}$ H, and $^{6}$ Li and $^{3}$ He. A microscopic three-cluster model is employed to study the dynamics of reactions occurring in the mirror nuclei $^{9}$ Be and $^{9}$ B. In a previous study [Phys. Rev. C {\bf 109}, 045803 (2024)], this model was successfully applied to investigate the resonance structure of $^{9}$ Be and $^{9}$ B, as well as reactions induced by the interaction of deuterons with $^{7}$ Li and $^{7}$ Be. A fairly good agreement between theoretical results and available experimental data was achieved. To the best of our knowledge, appropriate experimental data for the astrophysical S-factors of the reactions generated by the interaction of $^{6}$ Li with $^{3}$ H and with $^{3}$ He are currently unavailable. Thus, our results can serve as a guideline for future experimental efforts.
nucl-thPRC(2024)·4 citations
04
Systematic investigation of the nuclear multiple deformations in U+U collisions with A Multi-Phase Transport model
Zaining Wang🇨🇳 · Jinhui Chen🇨🇳 · Hao-jie Xu🇨🇳 · Jie Zhao🇨🇳
Relativistic heavy ion collisions provide a unique opportunity to study the shape of colliding nuclei, even up to higher-order multiple deformations. In this work, several observables that are sensitive to quadrupole and hexadecapole deformations of Uranium-238 in relativistic U+U collisions have been systematically investigated with A Multi-Phase Transport model. We find that the flow harmonic $v_{2}$ , the $v_{2}$ and mean transverse momentum correlation, and the three-particle asymmetry cumulant $ac_{2} {3}$ are sensitive to nuclear quadrupole deformation, while $ac_{2} {3}$ and nonlinear response coefficient $χ_{4, 22}$ are sensitive to nuclear hexadecapole deformation. Our results from transport model studies are in qualitative agreement with previous hydrodynamic studies. The results indicate that the uncertainties of the hexadecapole deformation of Uranium on the quadrupole deformation determination can be reduced by the abundance of correlation observables provided by the relativistic heavy ion collisions.
nucl-thnucl-exPRC(2024)·17 citations
05
Chiral properties of the nucleon interpolating current and $θ$ -dependent observables
Yohei Ema🇺🇸 · Ting Gao🇺🇸 · Maxim Pospelov🇺🇸 · Adam Ritz🇨🇦
We revisit the chiral properties of nucleon interpolating currents, and show that of the two leading order currents $j_{1}$ and $j_{2}$ , only two linear combinations $j_{1} \pm j_{2}$ transform covariantly under the anomalous $U (1)_{A}$ symmetry. As a result, calculations of quantities which vanish by symmetry in the chiral limit may produce unphysical results if carried out with different linear combinations of the currents. This includes observables such as electric dipole moments, induced by the QCD parameter $θ$ , and the $θ$ -dependence of the nucleon mass. For completeness, we also exhibit the leading order results for nucleon electric dipole moments ( $d_{n, p}$ ) induced by $θ$ , and the nucleon magnetic moments ( $μ_{n, p}$ ), when calculated using QCD sum rules for both the covariant choices of the nucleon interpolating current. The results in each channel, conveniently expressed as the ratios, $d_{n, p} / μ_{n, p}$ , are numerically consistent, and reflect the required physical dependence on $θ$ .
↳ hep-phhep-exnucl-thPRD(2024)·8 citations
06
Tentative estimates of $B (X (3872) \to π^{0} π^{0} χ_{c 1})$ and $B (X (3872) \to π^{+} π^{-} χ_{c 1})$
N. N. Achasov🇷🇺 · G. N. Shestakov🇷🇺
The rates of the $X (3872) \to π^{0} π^{0} χ_{c 1}$ and $X (3872) \to π^{+} π^{-} χ_{c 1}$ decays are estimated in the model of the triangle loop diagrams with charmed $D^{*} D ˉ D$ and $D ˉ^{*} D D ˉ$ mesons in the loops. There are the triangle logarithmic singularities in the physical region of the $X (3872) \to π^{0} π^{0} χ_{c 1}$ decay which manifest themselves as narrow peaks in the $π^{0} χ_{c 1}$ mass spectrum near the $D^{0} D ˉ^{0}$ threshold. The model predicts approximately the same branching fractions of the $X (3872) \to π^{0} π^{0} χ_{c 1}$ and $X (3872) \to π^{+} π^{-} χ_{c 1}$ decays at the level of about (0.8-1.7) $\times 1 0^{- 4}$ . A distinct prediction of the model is the value of the ratio $R = B (X (3872) \to π^{+} π^{-} χ_{c 1}) / B (X (3872) \to π^{0} π^{0} χ_{c 1}) \approx 1.1$ . It weakly depends on the $X (3872)$ resonance parameters and indicates a significant violation of the isotopic symmetry according to which one would expect $R = 2$ .
↳ hep-phhep-exnucl-exnucl-thPRD(2024)·7 citations
07
Refined determination of the weak mixing angle at low energy
M. Atzori Corona🇮🇹 · M. Cadeddu🇮🇹 · N. Cargioli🇮🇹 · F. Dordei🇮🇹 · C. Giunti🇮🇹
The weak mixing angle is a fundamental parameter of the electroweak theory of the standard model whose measurement in the low-energy regime is still not precisely determined. Different probes are sensitive to its value, among which atomic parity violation, coherent elastic neutrino-nucleus scattering and parity-violating electron scattering on different nuclei. In this work, we attempt for the first time to combine all these various determinations by performing a global fit that also keeps into account the unavoidable dependence on the experimentally poorly known neutron distribution radius of the nuclei employed, for which a new measurement using proton-cesium elastic scattering became available. By using all present direct determinations of the neutron distribution radius of cesium we find $sin^{2} ϑ_{W} = 0.239 6_{- 0.0019}^{+ 0.0020}$ , which should supersede the previous value determined from atomic parity violation on cesium. When including electroweak only, but also indirect, determinations of the neutron distribution radius of cesium the uncertainty reduces to 0.0017 maintaining the same central value, showing an excellent agreement independently of the method used.
↳ hep-phhep-exnucl-thPRD(2024)·17 citations
08
Zeno Effect Suppression of Gauge Drift in Quantum Simulations
Carter Ball🇺🇸 · Thomas D. Cohen🇺🇸
Quantum simulation of lattice gauge theories is a promising tool for the study of many complicated problems including ones with real-time dynamics. For gauge theories, however, there is a major challenge in maintaining gauge invariance during time evolution. Such theories have a full Hilbert space that is larger than the physical space -- the set of states which are gauge invariant or equivalently respect the Gauss law. While an exact implementation of Hamiltonian dynamics starting in the physical Hilbert space will keep the system in the physical space, various types of errors will inevitably produce components outside of it. This work proposes a method of suppressing this gauge drift via the Zeno effect. As in the standard picture of the Zeno effect, our method relies on frequent projection onto the physical subspace. Additionally, a technique is discussed to reduce the speed of the gauge drift, which helps to reduce the required frequency of projections. We demonstrate our method on a $Z_{2}$ gauge theory toy model.
↳ hep-latnucl-thquant-phPRA(2024)·9 citations
09
Study of possible $D N D^{*}$ bound states
Victor Montesinos🇪🇸 · Jing Song🇪🇸 · Wei-Hong Liang🇨🇳 · Eulogio Oset🇪🇸 · Juan Nieves🇪🇸 · Miguel Albaladejo🇪🇸
We start from a recently favored picture in which the $Λ_{c} (2940)$ and $Λ_{c} (2910)$ correspond mostly to $N D^{*}$ bound states with $J^{P} = 1/ 2^{-}, 3/ 2^{-}$ and then add a $D$ as a third particle, looking for the possible binding of the $D N D^{*}$ three body system within the framework of the Fixed Center Approximation. We find that the system is bound with respect to the corresponding $Λ_{c}^{*} D$ threshold with a binding of about $60$ MeV and a width of about $90$ MeV. Alternatively we assume a cluster of $N D$ and a $D^{*}$ meson interacting with the cluster and we find similar results. The observation of these states of $J^{P} = 1/ 2^{+}, 3/ 2^{+}$ would provide new and valuable information concerning the $D N$ and $D^{*} N$ interaction, an issue of current debate.
↳ hep-phnucl-thPRD(2024)·9 citations
10
Thermodynamic properties of a relativistic Bose gas under rigid rotation
E. Siri🇮🇷 · N. Sadooghi🇮🇷
We study the thermodynamic properties of a rigidly rotating relativistic Bose gas. First, we derive the solution of the equation of motion corresponding to a rotating complex Klein-Gordon field and determine the free propagator of this model utilizing the Fock-Schwinger proper-time method. Using this propagator, we then obtain the thermodynamic potential of this model in the zeroth and first perturbative level. In addition, we compute the nonperturbative ring contribution to this potential. Our focus is on the dependence of these expressions on the angular velocity, which effectively acts as a chemical potential. Using this thermodynamic potential, we calculate several quantities, including the pressure, angular momentum and entropy densities, heat capacity, speed of sound, and moment of inertia of this rigidly rotating Bose gas as functions of temperature ( $T$ ), angular velocity ( $Ω$ ), and the coupling constant ( $α$ ). We show that certain thermodynamic instabilities appear at high temperatures and large couplings. They are manifested as zero and negative values of the above quantities, particularly the moment of inertia and heat capacity. Zero moment of inertia leads to the phenomenon of supervorticity at certain $T$ or $α$ . Supervortical temperatures (couplings) decrease with increasing coupling (temperature). We also observe superluminal sound velocities at high $T$ and for large $α$ .
↳ hep-phhep-lathep-thnucl-thPRD(2024)·9 citations
11
On the absence of the Chiral Magnetic Effect in equilibrium QCD
Bastian B. Brandt🇩🇪 · Gergely Endrődi🇩🇪 · Eduardo Garnacho-Velasco🇩🇪 · Gergely Markó🇩🇪
In this paper we investigate the chiral magnetic effect (CME): the generation of an electric current due to a homogeneous background magnetic field and a homogeneous chiral imbalance in QCD. We demonstrate that the leading coefficient describing the CME vanishes in equilibrium, both for free fermions as well as in full QCD. Our full QCD results are based on continuum extrapolated lattice simulations using dynamical staggered quarks with physical masses as well as quenched Wilson quarks. We show that it is crucial that a gauge invariant ultraviolet regularization is used to compute the CME and elaborate on why some of the existing in-equilibrium calculations of this effect gave a nonzero result. We stress that our findings imply the absence of a time-independent CME current flowing in equilibrium QCD, but do not concern the CME as an out-of-equilibrium, time-dependent effect.
↳ hep-lathep-exhep-phhep-th+1JHEP(2024)·22 citations
12
Forward & Far-Forward Heavy Hadrons with JETHAD: A High-energy Viewpoint
Francesco Giovanni Celiberto🇪🇸
Inspired by the recent finding that semi-inclusive detections of heavy hadrons exhibit fair stabilization patterns in high-energy resummed distributions against (missing) higher-order corrections, we review and extend our studies on the hadroproduction of light and heavy hadrons tagged in forward and far-forward rapidity ranges. We analyze the NLL/NLO+ behavior of rapidity rates and angular multiplicities via the JETHAD method, where the resummation of next-to-leading energy logarithms and beyond is consistently embodied in the collinear picture. We explore kinematic regions that are within LHC typical acceptances, as well as novel sectors accessible thanks the combined tagging of a far-forward light or heavy hadron at future Forward Physics Facilities and a of central particle at LHC experiments via a precise timing-coincidence setup.
↳ hep-phhep-exnucl-exnucl-thParticles(2024)·18 citations

Affiliations

first authorsco-authorsvia INSPIRE