Nuclear Theory·nucl-th

Tuesday·September 19, 2023

21 papers—13 primary·8 cross-listed

01
[Submitted on 15 Sept 2023]
Probing hadron-quark phase transition in twin stars using $f$ -modes
Bikram Keshari Pradhan🇮🇳 · Debarati Chatterjee🇮🇳 · David Edwin Alvarez-Castillo🇵🇱
Although it is conjectured that a phase transition from hadronic to deconfined quark matter in the ultrahigh-density environment of Neutron Stars (NS), the nature of phase transition remains an unresolved mystery. Furthermore, recent efforts reveal that the finite surface tension effects can lead to a mixed phase with different geometric shapes (so-called "pasta" phases), leading to a smooth phase transition from hadronic to quark matter in the NS interior. Depending on whether there is a strong or a pasta-induced smooth first-order phase transition, one may expect a third family of stable, compact stars or "twin stars" to appear, with the same mass but different radii compared to NSs. The possibility of identifying twin stars using astrophysical observations has been a subject of interest. This study investigates the potential of probing the nature of the hadron-quark phase transition through future gravitational wave (GW) detections from fundamental ( $f$ -) mode oscillations in Neutron Stars. Using a newly developed model that parametrizes the hadron-quark phase transition with ``pasta phases," we calculate $f$ -mode characteristics within a full general relativistic framework. We then use Universal Relations in GW asteroseismology to derive stellar properties from the detected mode parameters. Our findings suggest that detecting GWs from $f$ -modes with third-generation GW detectors offers a promising scenario for the existence of twin stars. However, we also estimate various uncertainties in determining the mode parameters and conclude that these uncertainties make it more challenging to identify the nature of the hadron-quark phase transition.
Comments:
Accepted for publication in MNRAS. 18 pages and 18 Figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
arXiv:
2309.08775 [pdf]
MNRAS(2024)·23 citations
02
[Submitted on 15 Sept 2023]
Global trends of the electric dipole polarizability from shell-model calculations
José Nicolás Orce · Cebo Ngwetsheni · B. Alex Brown
Shell-model calculations of the electric dipole (E1) polarizability have been performed for the ground state of selected p- and sd-shell nuclei, substantially advancing previous knowledge. Our results are slightly larger compared with the somewhat more scattered photo-absorption cross-section data, albeit agreeing with ab initio calculations at shell closures and presenting a smooth trend that follows the leptodermus approximation provided by the finite-range droplet model (FRDM). The total E1 strengths also show an increasing trend proportional to the mass number which follows from the classical oscillator strength (TRK) sum rule for the E1 operator. The enhancement of the energy-weighted sum over E1 excitations with respect to the TRK sum rule arises from the use of experimental single-particle energies and the residual particle-hole interaction.
Comments:
9 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2309.08810 [pdf]
PRC(2023)·13 citations
03
[Submitted on 16 Sept 2023]
Azimuthal distribution of exponential format for particle collective motions in heavy-ion collisions under asynchronous assumption
Yicheng Feng🇺🇸
Particle azimuth distributions are widely studied in heavy-ion collisions. They are often expanded in Fourier series to extract anisotropic flow harmonics simultaneously. It was recently proposed that the different orders of flows could happen asynchronously or noninterdependently. This study extends this idea to an exponential format of the azimuth distribution, which makes it straightforward to extract the asynchronous flow coefficients. We compare these new coefficients to the conventional ones, and find consistency in the leading coefficient and discrepancy in higher-order ones.
Comments:
5 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2309.08824 [pdf]
0 citations
04
[Submitted on 16 Sept 2023]
Medium modification of pion production in low energy Au+Au collisions
Christian Kummer🇩🇪 · Kai Gallmeister🇩🇪 · Lorenz von Smekal🇩🇪
There is a major mismatch between the charged pion yields in Au+Au collisions at low energies calculated by various transport models and the experimental measured values from the Hades collaboration. In this work, reasonable improvements on the equation of state, in-medium modification of cross sections, and the influence of the nuclear potential for Delta resonances will be investigated in the framework of the GiBUU transport model. As a result, we demonstrate that theoretical calculations can indeed describe the charged pion yields measured by Hades for Au+Au collisions rather well, but that a mismatch then remains between calculations and data for the yields of neutral pions extracted from dileptons within the same experiment.
Comments:
16 pages, 15 figures. Text and figures improved, 2 figures added
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2309.09042 [pdf]
PRC(2024)·6 citations
05
[Submitted on 17 Sept 2023]
Conservation and breaking of pseudospin symmetry
T.-T. Sun · Z. P. Li · P. Ring
Pseudospin symmetry (PSS) is a relativistic dynamical symmetry connected with the lower component of the Dirac spinor. Here, we investigate the conservation and breaking of PSS in the single-nucleon resonant states, as an example, using Green's function method that provides a novel way to precisely describe not only the resonant energies and widths but also the spacial density distributions for both narrow and wide resonances. The PSS restoration and breaking are perfectly displayed in the evolution of resonant parameters and density distributions with the potential depth: In the PSS limit, i.e., when the attractive scalar and repulsive vector potentials have the same magnitude but opposite sign, PSS is exactly conserved with strictly the same energy and width between the PS partners as well as identical density distributions of the lower components. As the potential depth increases, the PSS is broken gradually with energy and width splittings and a phase shift in the density distributions.
Comments:
5 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2309.09266 [pdf]
PLB(2023)·9 citations
06
[Submitted on 17 Sept 2023]
Persistent vibrational structure in $^{110 - 116}$ Cd
N. Gavrielov🇺🇸 · J.E. Garcia-Ramos🇪🇸 · P. Van Isacker🇫🇷 · A. Leviatan🇮🇱
The empirical spectra and $E 2$ decay rates in $^{110, 112, 114, 116}$ Cd are shown to be consistent with a vibrational interpretation for low-lying normal states, coexisting with a single deformed $γ$ -soft band of intruder states. The observed deviations from this paradigm show up in particular non-yrast states, which are properly described by a Hamiltonian with U(5) partial dynamical symmetry. The latter is characterized by a good (broken) symmetry in most (in selected) normal states, weakly coupled to intruder states.
Comments:
5 pages, 3 figures, 2 tables, accepted for publication as a Letter in Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2309.09285 [pdf]
PRC(2023)·12 citations
07
[Submitted on 17 Sept 2023]
Global properties of nuclei at finite-temperature within the covariant energy density functional theory
Ante Ravlić · Esra Yüksel · Tamara Nikšić · Nils Paar
In stellar environments nuclei appear at finite temperatures, becoming extremely hot in core-collapse supernovae and neutron star mergers. However, due to theoretical and computational complexity, most model calculations of nuclear properties are performed at zero temperature, while those existing at finite temperatures are limited only to selected regions of the nuclide chart. In this study we perform the global calculation of nuclear properties for even-even $8 \leq Z \leq 104$ nuclei at temperatures in range $0 \leq T \leq 2$ MeV. Calculations are based on the finite temperature relativistic Hartree-Bogoliubov model supplemented by the Bonche-Levit-Vautherin vapor subtraction procedure. We find that near the neutron-drip line the continuum states have significant contribution already at moderate temperature $T \approx 1$ MeV, thus emphasising the necessity of the vapor subtraction procedure. Results include neutron emission lifetimes, quadrupole deformations, neutron skin thickness, proton and neutron pairing gaps, entropy and excitation energy. Up to the temperature $T \approx 1$ MeV nuclear landscape is influenced only moderately by the finite-temperature effects, mainly by reducing the pairing correlations. As the temperature increases further, the effects on nuclear structures become pronounced, reducing both the deformations and the shell effects.
Comments:
18 pages, 14 figures, submitted to Physical Review C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2309.09302 [pdf]
PRC(2024)·9 citations
08
[Submitted on 17 Sept 2023]
Fission Fragment Mass and Kinetic Energy Yields of Fermium Isotopes
K. Pomorski🇵🇱 · A. Dobrowolski🇵🇱 · B. Nerlo-Pomorska🇵🇱 · M. Warda🇵🇱 · A. Zdeb🇵🇱 · J. Bartel🇫🇷 · H. Molique🇫🇷 · C. Schmitt🇫🇷 · Z. G. Xiao🇨🇳 · Y. J. Chen🇨🇳 · L. L. Liu🇨🇳
A rapidly converging 4-dimensional Fourier shape parametrization is used to model the fission process of heavy nuclei. Potential energy landscapes are computed within the macroscopic-microscopic approach, on top of which the multi-dimensional Langevin equation is solved to describe the fission dynamics. Charge equilibration at scission and de-excitation by neutron evaporation of the primary fragments after scission is investigated. The model describes various observables, including fission-fragment mass, charge, and kinetic energy yields, as well as post-scission neutron multiplicities and, most importantly, their correlations, which are crucial to unravel the complexity of the fission process. The parameters of the dynamical model were tuned to reproduce experimental data obtained from thermal neutron-induced fission of $^{235}$ U, which allows us to discuss the transition from asymmetric to symmetric fission along the Fm isotopic chain.
Comments:
Presented at the Mazurian Lakes Conference on Physics, 2023, Poland
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2309.09322 [pdf]
Acta Phys.Polon.B(2023)·2 citations
09
[Submitted on 17 Sept 2023]
Scissors mode in transuranium elements
E. B. Balbutsev · I. V. Molodtsova
The scissors mode is investigated in the actinides region, including even-even superheavy nuclei up to $^{256}$ No, within the Time Dependent Hartree-Fock-Bogoliubov (TDHFB) approach. The solution of TDHFB equations by the Wigner Function Moments (WFM) method predicts a splitting of the scissors mode into three intermingled branches due to spin degrees of freedom. Both the calculated energy centroid and integrated $M 1$ strength in $^{254}$ No are in good agreement with the results of recent measurements performed by the Oslo method. The energy centroids and summed $B (M 1)$ values for others transuranium nuclides are predicted. The calculations are performed also for $^{232}$ Th and $^{236, 238}$ U isotopes using an updated compilation of deformation parameters. The results are compared with that obtained previously by WFM theory and with the latest experimental data. Progress has been achieved in theoretical understanding of the origins of double-humped structure of scissors spectrum observed in the Actinides.
Comments:
9 pages, 3 figures, 5 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2309.09340 [pdf]
EPJA(2024)·6 citations
10
[Submitted on 18 Sept 2023]
Suppression of the elastic scattering cross section for 17Ne + 208Pb system
Kyoungsu Heo · Myung-Ki Cheoun · Ki-Seok Choi · K. S. Kim · W. Y. So
We investigated the elastic scattering, inelastic scattering, breakup reaction, and total fusion reactions of 17Ne + 208Pb system using the optical model (OM) and a coupled channel (CC) approaches. The aim of this study is to elucidate the suppress of the elastic cross-section that is invisible in proton-rich nuclei such as 8B and 17F projectiles but appears in neutron-rich nuclei such as 11Li and 11Be projectiles. The results revealed that this suppression was caused mainly by the nuclear interaction between the projectile and target nucleus rather than the strong Coulomb interaction observed in neutron-rich nuclei and the contributions of Coulomb excitation interaction due to two low-lying E2 resonance states are relatively small. From the simultaneous chi-square analysis of the 17Ne + 208Pb system, we can infer a strong suppression effect in the elastic scattering cross-section due to the nuclear interaction between the projectile and target nucleus, rather than the Coulomb interaction as observed in neutron-rich nuclei. Also, the contribution of the direct reaction, comprising the inelastic scattering and breakup reaction cross-sections, accounted for almost half of the total reaction. Finally, we perform the CC calculation using the parameters obtained from our OM calculation but our CC calculations could not explain the 15O production cross section.
Comments:
20 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2309.09445 [pdf]
PRC(2024)·4 citations
11
[Submitted on 18 Sept 2023]
Generator coordinate method for nuclear octupole excitations: status and perspectives
E. F. Zhou · J. M. Yao
Strong octupole correlations have been observed in the low-lying states of atomic nuclei across various mass regions. In this review, we provide an overview of Beyond Mean-Field (BMF) studies of nuclear octupole collective motions with Generator Coordinate Method (GCM) in combination with quantum-number projections that are implemented to restore the broken symmetries in nuclear mean-field states. We highlight recent developments within this framework and their applications to excitation spectra and electromagnetic transition rates in octupole-shaped nuclei and hypernuclei. We discuss the novel phenomena of nucleon clustering in light nuclei. Additionally, we explore the phase transition from octupole vibrations to rotational motions as spin increases in heavy nuclei. Lastly, we examine the status and future prospects of studies on octupole deformation effects in nuclear Schiff moments. These studies, along with the upper limits of atomic Electric Dipole Moment (EDM), impose stringent constraints on beyond-standard-model time-reversal-violating nucleon-nucleon interactions.
Comments:
56 pages, 21 figures, an invited review for the journal Int. J. Mod. Phys. E
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2309.09488 [pdf]
IJMPE(2023)·9 citations
12
[Submitted on 18 Sept 2023]
Crossover equation of state based on color-molecular-dynamics
Nobutoshi Yasutake🇯🇵 · Toshiki Maruyama🇯🇵
The equation of State for dense matter is studied with color molecular dynamics, in which hadron matter and quark matter are automatically distinguished only from quark color state. The quark-quark interactions are optimized to be consistent with saturation properties: symmetric energy, $L -$ parameter, and incompressibility around nuclear density. In the calculations, the degrees of freedom of colors are solved at each numerical step, although the flavors are fixed as up or down quarks. The resultant mass-radius relations also satisfy the observational constraints such as the gravitational wave observations, NICER, and ``{\it the two-solar mass observations}" of neutron stars. In this model with the allowed parameter range, deconfined quark matter appears in the core of neutron stars via crossover. Although the current constraints from the observations are not enough to conclude whether quark matter appears at high-density region, our method would help to understand high-density material properties inside neutron stars in the future.
Comments:
9 pages, 8 figures (Phys. Rev. D accepted)
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2309.09632 [pdf]
PRD(2024)·6 citations
13
[Submitted on 18 Sept 2023]
Probe nuclear structure using the anisotropic flow at the Large Hadron Collider
Zhiyong Lu · Mingrui Zhao · Jiangyong Jia · You Zhou
Recent studies have shown that the shape and radial profile of the colliding nuclei have strong influences on the initial condition of the heavy ion collisions and the subsequent development of the anisotropic flow. Using A Multi-Phase Transport model (AMPT) model, we investigated the impact of nuclear quadrupole deformation $β_{2}$ and nuclear diffuseness $a_{0}$ of $^{129}$ Xe on various of flow observables in Xe--Xe collisions at $\sqrtnn =$ 5.44 TeV. We found that $β_{2}$ has a strong influence on central collisions while $a_{0}$ mostly influences the mid-central collisions. The relative change of flow observables induced by a change in $β_{2}$ and $a_{0}$ are also found to be insensitive to the values of parameters controlling the strength of the interaction among final state particles. Our study demonstrates the potential for constraining the initial condition of heavy ion collisions using future system scans at the LHC.
Comments:
25 pages, for the EPJA Topical Issues
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2309.09663 [pdf]
EPJA(2023)·19 citations
14
[Submitted on 15 Sept 2023] (cross-list from hep-ph)
Constraining the low-energy S=-2 meson-baryon interaction with two-particle correlations
V. Mantovani Sarti🇩🇪 · A. Feijoo🇪🇸 · I. Vidaña🇮🇹 · A. Ramos🇪🇸 · F. Giacosa🇵🇱 · T. Hyodo🇯🇵 · Y. Kamiya🇯🇵
The two-particle correlation technique applied to $K^{-} Λ$ pairs in pp collisions at LHC recently provided the most precise data on the strangeness $S = - 2$ meson-baryon interaction. In this letter, we use for the first time femtoscopic data to constrain the parameters of a low-energy effective QCD Lagrangian. The tuned model delivers new insights on the molecular nature of the $Ξ (1620)$ and $Ξ (1690)$ states. This procedure opens the possibility to determine higher order corrections, directly constraining QCD effective models particularly in the multi-strange and charm sectors.
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2309.08756 [pdf]
PRD(2024)·41 citations
15
[Submitted on 17 Sept 2023] (cross-list from astro-ph.HE)
Effects of nuclear matter properties in neutron star mergers
Maximilian Jacobi🇩🇪 · Federico Maria Guercilena🇮🇹 · Sabrina Huth🇩🇪 · Giacomo Ricigliano🇩🇪 · Almudena Arcones🇩🇪 · Achim Schwenk🇩🇪
The dynamics in mergers of binary neutron star (BNS) systems depend sensitively on the equation of state (EOS) of dense matter. This has profound implications on the emission of gravitational waves (GWs) and the ejection of matter in the merger and post-merger phases and is thus of high interest for multi-messenger astronomy. Today, a variety of nuclear EOSs are available with various underlying microphysical models. This calls for a study to focus on EOS effects from different physical nuclear matter properties and their influence on BNS mergers. We perform simulations of equal-mass BNS mergers with a set of 9 different EOSs based on Skyrme density functionals. In the models, we systematically vary the effective nucleon mass, incompressibility, and symmetry energy at saturation density. This allows us to investigate the influence of specific nuclear matter properties on the dynamics of BNS mergers. We analyze the impact of these properties on the merger dynamics, the fate of the remnant, disk formation, ejection of matter, and gravitational wave emission. Our results indicate that some aspects of the merger are sensitive to the EOS around saturation density while others are sensitive to the behavior towards higher densities, e.g., characterized by the slope of the pressure as a function of density. The detailed density dependence of the EOS thus needs to be taken into account to describe its influence on BNS mergers.
Comments:
17 pages, 19 figures, published version
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2309.09233 [pdf]
MNRAS(2023)·22 citations
16
[Submitted on 17 Sept 2023] (cross-list from hep-lat)
Study of the effects of external imaginary electric field and chiral chemical potential on quark matter
Ji-Chong Yang🇨🇳 · Xin Zhang🇨🇳 · Jian-Xing Chen🇨🇳
The behavior of quark matter with both external electric field and chiral chemical potential is theoretically and experimentally interesting to consider. In this paper, the case of simultaneous presence of imaginary electric field and chiral chemical potential is investigated using the lattice QCD approach with $N_{f} = 1 + 1$ dynamical staggered fermions. We find that overall both the imaginary electric field and the chiral chemical potential can exacerbate chiral symmetry breaking, which is consistent with theoretical predictions. However we also find a non-monotonic behavior of chiral condensation at specific electric field strengths and chiral chemical potentials. In addition to this, we find that the behavior of Polyakov loop in the complex plane is not significantly affected by chiral chemical potential in the region of the parameters consider in this paper.
Comments:
21 pages, 20 figures
Subjects:
High Energy Physics — Lattice (hep-lat); cs.NA (cs.NA); High Energy Physics — Phenomenology (hep-ph); math.NA (math.NA); Nuclear Theory (nucl-th)
arXiv:
2309.09281 [pdf]
EPJC(2024)·6 citations
17
[Submitted on 17 Sept 2023] (cross-list from physics.flu-dyn)
Analytical structure of the binary collision integral and the ultrarelativistic limit of transport coefficients of an ideal gas
David Wagner · Victor E. Ambrus · Etele Molnar
In this paper we discuss the analytical properties of the binary collision integral for a gas of ultrarelativistic particles interacting via a constant cross-section. Starting from a near-equilibrium expansion over a complete basis of irreducible tensors in momentum space we compute the linearized collision matrices analytically. Using these results we then numerically compute all transport-coefficients of relativistic fluid dynamics with various power-counting schemes that are second-order in Knudsen and/or inverse Reynolds numbers. Furthermore, we also exactly compute the leading-order contribution with respect to the particle mass to the coefficient of bulk viscosity, the relaxation time, and other second-order transport coefficients of the bulk viscous pressure.
Comments:
Published version
Subjects:
Fluid Dynamics (physics.flu-dyn); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2309.09335 [pdf]
PRD(2024)·16 citations
18
[Submitted on 18 Sept 2023] (cross-list from hep-ph)
The LHC as a Neutrino-Ion Collider
Juan M. Cruz-Martinez🇨🇭 · Max Fieg🇺🇸 · Tommaso Giani🇳🇱 · Peter Krack🇳🇱 · Toni Mäkelä🇵🇱 · Tanjona Rabemananjara🇳🇱 · Juan Rojo🇳🇱
Proton-proton collisions at the LHC generate a high-intensity collimated beam of neutrinos in the forward (beam) direction, characterised by energies of up to several TeV. The recent observation of LHC neutrinos by FASER $ν$ and SND@LHC signals that this hitherto ignored particle beam is now available for scientific inquiry. Here we quantify the impact that neutrino deep-inelastic scattering (DIS) measurements at the LHC would have on the parton distributions (PDFs) of protons and heavy nuclei. We generate projections for DIS structure functions for FASER $ν$ and SND@LHC at Run III, as well as for the FASER $ν$ 2, AdvSND, and FLArE experiments to be hosted at the proposed Forward Physics Facility (FPF) operating concurrently with the High-Luminosity LHC (HL-LHC). We determine that up to one million electron- and muon-neutrino DIS interactions within detector acceptance can be expected by the end of the HL-LHC, covering a kinematic region in $x$ and $Q^{2}$ overlapping with that of the Electron-Ion Collider. Including these DIS projections into global (n)PDF analyses, specifically PDF4LHC21, NNPDF4.0, and EPPS21, reveals a significant reduction of PDF uncertainties, in particular for strangeness and the up and down valence PDFs. We show that LHC neutrino data enables improved theoretical predictions for core processes at the HL-LHC, such as Higgs and weak gauge boson production. Our analysis demonstrates that exploiting the LHC neutrino beam effectively provides CERN with a "Neutrino-Ion Collider" without requiring modifications in its accelerator infrastructure.
Comments:
42 pages, 22 figures. Added detailed studies on fluxes uncertainties
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2309.09581 [pdf]
EPJC(2024)·71 citations
19
[Submitted on 18 Sept 2023] (cross-list from hep-ph)
Triangle and box diagrams in coupled-channel systems from the chiral Lagrangian
Tobias Isken🇩🇪 · Xiao-Yu Guo🇨🇳 · Yonggoo Heo🇩🇪 · Csaba L. Korpa🇭🇺 · Matthias F.M. Lutz🇩🇪
We perform an analysis of triangle- and box-loop contributions to the generalized potential in the scattering of Goldstone bosons off the J^P= 0^- and 1^- charmed mesons. Particular emphasis is put on the use of on-shell mass parameters in such contributions in terms of a renormalization scheme that ensures the absence of power-counting violating terms. This is achieved with a systematically extended set of Passarino--Veltman basis functions, that leads to manifest power-counting conserving one-loop expressions and avoids the occurrence of superficial kinematical singularities. Compact expressions to chiral order three and four are presented that are particularly useful in coding such coupled-channel systems. Our formal results are generic and prepare analogous computations for other systems, like meson-baryon scattering from the chiral Lagrangian.
Comments:
58 pages, 7 figures and 2 tables, minor corrections and extensions
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2309.09695 [pdf]
PRD(2024)·8 citations
20
[Submitted on 18 Sept 2023] (cross-list from astro-ph.HE)
Quasi-periodic oscillations during magnetar giant flares in the strangeon star model
Hong-Bo Li · Yacheng Kang · Zexin Hu · Lijing Shao · Cheng-Jun Xia · Ren-Xin Xu
Soft gamma-ray repeaters (SGRs) are widely understood as slowly rotating isolated neutron stars. Their generally large spin-down rates, high magnetic fields, and strong outburst energies render them different from ordinary pulsars. In a few giant flares (GFs) and short bursts of SGRs, high-confidence quasi-periodic oscillations (QPOs) were observed. Although remaining an open question, many theoretical studies suggest that the torsional oscillations caused by starquakes could explain QPOs. Motivated by this scenario, we systematically investigate torsional oscillation frequencies based on the strangeon-star (SS) model with various values of harmonic indices and overtones. To characterize the strong-repulsive interaction at short distances and the non-relativistic nature of strangeons, a phenomenological Lennard-Jones model is adopted. We show that, attributing to the large shear modulus of SSs, our results explain well the high-frequency QPOs ( $≳ 150 Hz$ ) during the GFs. The low-frequency QPOs ( $≲ 150 Hz$ ) can also be interpreted when the ocean-crust interface modes are included. We also discuss possible effects of the magnetic field on the torsional mode frequencies. Considering realistic models with general-relativistic corrections and magnetic fields, we further calculate torsional oscillation frequencies for quark stars. We show that it would be difficult for quark stars to explain all QPOs in GFs. Our work advances the understanding of the nature of QPOs and magnetar asteroseismology.
Comments:
9 pages, 7 figures; accepted by MNRAS
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
arXiv:
2309.09847 [pdf]
MNRAS(2024)·8 citations
21
[Submitted on 18 Sept 2023] (cross-list from hep-ph)
Cut structures and an observable singularity in the three-body threshold dynamics: the $T_{cc}^{+}$ case
Jun-Zhang Wang🇨🇳 · Zi-Yang Lin🇨🇳 · Shi-Lin Zhu🇨🇳
The three-body threshold effect, the distinctive and intriguing non-perturbative dynamics in the low-energy hadron-hadron scattering, has acquired compelling significance in the wake of the recent observation of the double-charm tetraquark $T_{cc}^{+}$ . This dynamics is characterized by the emergence of singular points and branch cuts within the interaction potential, occurring when the on-shell condition of the mediated particle is satisfied. The presence of these potential singularities indicates that the system is no longer Hermitian and also poses intractable challenges in obtaining exact solutions for dynamical scattering amplitudes. In this work, we develop a complex scaled Lippmann-Schwinger equation as an operation of analytical continuation of the $T$ matrix to resolve this problem. Through a practical application to the $D D^{*} \to D D^{*}$ process, we reveal complicated cut structures of the three-body threshold dynamics in the complex plane, primarily stemming from the one-pion exchange. Notably, our methodology succeeds in reproducing the $T_{cc}^{+}$ structure, in alignment with the quasi-bound pole derived from the complex scaling method within the Schrödinger equation framework. More remarkably, after solving the on-shell $T$ matrix on the positive real axis of momentum plane, we find an extra new structure in the $D D^{*}$ mass spectrum, which arises from a right-hand cut at a physical pion mass and should be observable in Lattice QCD simulations and future high-energy experiments.
Comments:
9 pages and 9 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2309.09861 [pdf]
PRD(2024)·15 citations

Affiliations

first authorsco-authorsvia INSPIRE