Nuclear Theory·nucl-th

Tuesday·December 12, 2023

13 papers—5 primary·8 cross-listed

01
[Submitted on 8 Dec 2023]
Exact Polarization of Particles of Any Spin at Global Equilibrium
Andrea Palermo🇺🇸
The polarization of the $Λ$ particle offers the unique opportunity to study the hydrodynamic gradients in the Quark-Gluon Plasma formed in heavy-ion collisions. However, the theoretical formula commonly used to calculate polarization is only a linear order expansion in thermal vorticity and neglects higher-order corrections. Here, I present an exact calculation to all orders in (constant) thermal vorticity at global equilibrium, obtaining the analytic form of the spin density matrix and the polarization vector for massive particles of any spin. Finally, I extend these results to local equilibrium and assess their phenomenological impact by numerically calculating the polarization vector in a 3+1 hydrodynamic simulation.
Comments:
4 pages, proceedings of QM2023
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Theory (hep-th)
arXiv:
2312.05380 [pdf]
EPJ Web Conf.(2024)·4 citations
02
[Submitted on 9 Dec 2023]
Correlating isothermal compressibility to nucleon fluctuations in the inner crust of neutron stars
R. Shafieepour · H. R. Moshfegh · J. Piekarewicz
The question of how and which physical observables or thermodynamic parameters can best predict the onset of a possible phase transition in the inner crust of neutron stars remains largely unresolved. Using semiclassical Monte Carlo simulations, we investigate the isothermal compressibility and density fluctuations in a region of relevance to the dynamics of the inner crust. We show that the isothermal compressibility serves as a robust observable to characterize the transition from the non-uniform crust to the uniform core for proton fractions over 0.2. Moreover, we show explicitly how the two-component isothermal compressibility, computed using the Kirkwood-Buff theory, is directly connected to the fluctuations in the number density, recorded in the grand canonical ensemble by monitoring the number of particles in a small volume located at the center of the simulation box. That is, we compute mean-square particle fluctuations and compare them against the isothermal compressibility for different proton fractions. Although our results show that the mean-square particle fluctuations are proportional to the isothermal compressibility, the lack of a perfect correlation is attributed to the relatively small number of particles included in the simulations. The non-unity slope observed in the dimensionless isothermal compressibility-total nucleon fluctuation variance relationship suggests that the inner crust of neutron stars is composed of anisotropic and inhomogeneous matter.
Comments:
10 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2312.05613 [pdf]
PRC(2024)·0 citations
03
[Submitted on 11 Dec 2023]
Effect of hadronic interaction on the flow of $K^{* 0}$
Tribhuban Parida🇮🇳 · Sandeep Chatterjee🇮🇳 · Md. Nasim🇮🇳
We explore the implications of the late stage hadronic rescattering phase on the flow of $K^{* 0}$ . The model calculations are done using a (3+1)-dimensional hybrid framework, incorporating both hydrodynamic evolution and hadronic transport that is calibrated to agree with bulk observables including the elusive rapidity differential $v_{1}$ of light-flavor hadrons. We find that the late stage hadronic rescattering phase causes significant qualitative modification of the $K^{* 0}$ $v_{1}$ resulting in $\frac{d v _{1}}{d y} (K^{* 0}) - \frac{d v _{1}}{d y} (K^{+})$ and $\frac{d v _{1}}{d y} (ϕ) - \frac{d v _{1}}{d y} (K^{+})$ to have opposite signs with the effect being more pronounced in central collisions as compared to peripheral ones due to the larger multiplicity as well as longer duration of the hadronic phase. Further, this effect is enhanced in low-energy collisions owing to a stronger breaking of boost invariance. On the contrary, the influence of the hadronic phase on the $K^{* 0}$ elliptic flow $v_{2}$ is found to be less significant and quantitative.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2312.06359 [pdf]
PRC(2024)·7 citations
04
[Submitted on 11 Dec 2023]
Constraints on initial baryon stopping and equation of state from directed flow
Lipei Du🇨🇦 · Chun Shen🇺🇸 · Sangyong Jeon🇨🇦 · Charles Gale🇨🇦
Our investigation focuses on the rapidity-dependent directed flow, $v_{1} (y)$ , of identified hadrons in Au+Au collisions across a broad range of $s_{NN}$ from 7.7 to 200 GeV. Employing a (3+1)-dimensional hybrid framework, our study successfully reproduces the characteristic features of the measured $v_{1} (y)$ for both mesons and baryons across the considered beam energies. Notably, our analysis reveals the constraining power of baryonic $v_{1} (y)$ on the initial baryon stopping mechanism. Together with mesonic $v_{1} (y)$ , the directed flow serves as a crucial tool for probing the equation of state governing dense nuclear matter at finite chemical potentials.
Comments:
4 pages, 1 figure. Contribution to the proceedings of Quark Matter 2023 (Houston, TX, 3-9 Sep. 2023)
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2312.06468 [pdf]
EPJ Web Conf.(2024)·2 citations
05
[Submitted on 4 Dec 2023]
Interplay of baryonic chiral partners in fluctuations of net-baryon number density
Michał Marczenko🇵🇱 · Volker Koch🇺🇸 · Krzysztof Redlich🇵🇱 · Chihiro Sasaki🇵🇱
In this contribution, we use the parity doublet model to investigate the fluctuations of the net-baryon number density. We discuss the systematics of the susceptibilities and their ratios for nucleons of positive and negative parity, as well as their correlator. We demonstrate that the fluctuations of positive-parity nucleon do not reflect the fluctuations of the total net-baryon number at the chiral phase transition.
Comments:
prepared for the Quark Matter 2023 proceedings
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2312.06621 [pdf]
EPJ Web Conf.(2024)·0 citations
06
[Submitted on 8 Dec 2023] (cross-list from quant-ph)
Quantum Algorithms for Simulating Nuclear Effective Field Theories
James D. Watson🇺🇸 · Jacob Bringewatt🇺🇸 · Alexander F. Shaw🇺🇸 · Andrew M. Childs🇺🇸 · Alexey V. Gorshkov🇺🇸 · Zohreh Davoudi🇺🇸
Quantum computers offer the potential to simulate nuclear processes that are classically intractable. With the goal of understanding the necessary quantum resources to realize this potential, we employ state-of-the-art Hamiltonian-simulation methods, and conduct a thorough algorithmic analysis, to estimate the qubit and gate costs to simulate low-energy effective field theories (EFTs) of nuclear physics. Within the framework of nuclear lattice EFT, we obtain simulation costs for the leading-order pionless and pionful EFTs. For the latter, we consider both static pions represented by a one-pion-exchange potential between the nucleons, and dynamical pions represented by relativistic bosonic fields coupled to non-relativistic nucleons. Within these models, we examine the resource costs for the tasks of time evolution and energy estimation for physically relevant scales. We account for model errors associated with truncating either long-range interactions in the one-pion-exchange EFT or the pionic Hilbert space in the dynamical-pion EFT, and for algorithmic errors associated with product-formula approximations and quantum phase estimation. We find that the pionless EFT is the least costly to simulate, followed by the one-pion-exchange theory, then the dynamical-pion theory. We demonstrate how symmetries of the low-energy nuclear Hamiltonians can be utilized to obtain tighter error bounds. By retaining the locality of nucleonic interactions when mapped to qubits, we achieve reduced circuit depth and substantial parallelization. In the process, we develop new methods to bound the algorithmic error for classes of fermionic number-preserving Hamiltonians, and obtain tighter Trotter error bounds by explicitly computing nested commutators of Hamiltonian terms. Compared to previous estimates for the pionless EFT, our results represent an improvement by several orders of magnitude.
Comments:
v3: 50 pages + 53 page appendices, 26 figures. Minor fixes
Subjects:
Quantum Physics (quant-ph); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2312.05344 [pdf]
40 citations
07
[Submitted on 8 Dec 2023] (cross-list from hep-ph)
Production of the $X (4014)$ as the spin-2 partner of $X (3872)$ in $e^{+} e^{-}$ collisions
Pan-Pan Shi🇨🇳 · Vadim Baru🇩🇪 · Feng-Kun Guo🇨🇳 · Christoph Hanhart🇩🇪 · Alexey Nefediev🇸🇮
In 2021, the Belle collaboration reported the first observation of a new structure in the $ψ (2 S) γ$ final state produced in the two-photon fusion process. In the hadronic molecule picture, this new structure can be associated with the shallow isoscalar $D^{*} D ˉ^{*}$ bound state and as such is an excellent candidate for the spin-2 partner of the $X (3872)$ with the quantum numbers $J^{P C} = 2^{++}$ conventionally named $X_{2}$ . In this work we evaluate the electronic width of this new state and argue that its nature is sensitive to its total width, the experimental measurement currently available being unable to distinguish between different options. Our estimates demonstrate that the planned Super $τ$ -Charm Facility offers a promising opportunity to search for and study this new state in the invariant mass distributions for the final states $J / ψ γ$ and $ψ (2 S) γ$ .
Comments:
9 pages, 1 figures. Version to appear in CPL
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2312.05389 [pdf]
Chin.Phys.Lett.(2024)·14 citations
08
[Submitted on 9 Dec 2023] (cross-list from hep-ph)
Energy and system size dependence of strongly intensive fluctuation measures in heavy-ion collisions at FAIR energies
Bushra Ali🇮🇳 · Shakeel Ahmad🇮🇳 · A. Ahmad🇮🇳
Event-by-event fluctuations of multiplicity and transverse momentum of charged hadrons produced in heavy-ion collisions at FAIR energies, 10A, 20A, 30A and 40A GeV are studied in the framework of relativistic transport model, URQMD. Dependence of two families of strongly intensive measures of multiplicity( $N$ ) and transverse momentum( $p_{T}$ ) fluctuations, $Δ [p_{T}, N]$ and $Σ [p_{T}, N]$ , on collision centrality, centrality bin-widths and pseudorapidity windows are examined. Attempts are also made to study $N N$ , $N$ $p_{T}$ and $p_{T}$ $p_{T}$ fluctuations using two window analysis method. The findings suggest that the measure, $Δ [p_{T}, N]$ be dealt with proper selection of centrality intervals. This measure also exhibits a strong dependence on the widths of $η$ windows. The variable $Σ [p_{T}, N]$ , however, is observed to be insensitive to the centrality bin-widths and shows a variation of $< 5%$ with the widths of $η$ windows. The analysis of data after event mixing gives $Δ [p_{T}, N]$ and $Σ [p_{T}, N]$ values as $\sim 1$ irrespective of the widths of $η$ windows and collision centrality, as predicted by model of independent particle emission, IPM. The study of joint fluctuations of the two quantities on two $η$ windows separated in $η$ space, reveals that $Σ [N_{F}, N_{B}]$ values are $\sim 1$ irrespective of the position of $η$ windows whereas, the values of $Σ [N_{F}, p_{T_{B}}]$ and $Σ [p_{T_{F}}, p_{T_{B}}]$ firstly increase with $η_{se p}$ and later acquire saturations. The observed trend of centrality dependence of $Σ [N_{F}, N_{B}], Σ [N_{F}, p_{T_{B}}]$ and $Σ [p_{T_{F}}, p_{T_{B}}]$ agrees fairly well with those observed in MC simulated studies carried out for AA collisions at LHC energies in the framework model of string fusion.
Comments:
Accepted in Journal of Physics G
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2312.05493 [pdf]
J.Phys.G(2024)·1 citation
09
[Submitted on 9 Dec 2023] (cross-list from astro-ph.HE)
Torsional oscillations of magnetized neutron stars: Impacts of Landau-Rabi quantization of electron motion
Ling Cheung · Lap-Ming Lin · Nicolas Chamel
Torsional oscillations of magnetized neutron stars have been well studied since they may be relevant to the physical interpretation of some of the observed quasiperiodic oscillations in the magnetar giant flares. In the crustal region of a magnetar, the strong magnetic field can alter the equation of state and composition due to the Landau-Rabi quantization of electron motion. In this paper, we study this effect on the crust-confined, torsional oscillation modes of neutron stars with mixed poloidal-toroidal magnetic fields in general relativity under the Cowling approximation. Furthermore, the inner and outer crusts are treated consistently based on the nuclear-energy density functional theory. Depending on the magnetic-field configurations, we find that the Landau-Rabi quantization of electrons can change the frequencies of the fundamental torsional oscillation mode of $1.4 M_{⊙}$ neutron star models with a normal fluid core by about 10% when the magnetic field strength at the pole reaches the order of $1 0^{16}$ G. The shift can even approach 20% at a field strength of $1 0^{15}$ G for neutron stars with a simple model of superconducting core where the magnetic field is assumed to be expelled completely.
Comments:
18 pages, 15 figures, accepted for publication in PRD
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
arXiv:
2312.05676 [pdf]
PRD(2024)·1 citation
10
[Submitted on 10 Dec 2023] (cross-list from hep-ph)
Predicting Quadrupole deformation via anisotropic flow and transverse momentum spectra in isotopic $\prescript 128 - 135 54 Xe$ collisions at LHC
Saraswati Pandey🇮🇳 · B. K. Singh🇮🇳
In the hydrodynamical description of heavy-ion collisions, the elliptic flow $v_{2}$ and triangular flow $v_{3}$ are sensitive to the quadrupole deformation $β_{2}$ of the colliding nuclei. We produce $v_{2}$ and $v_{3}$ ratios qualitatively and quantitatively in most-central Xe-Xe collisions at 5.44 TeV. By employing HYDJET++ model, we study the sensitivity of anisotropic flow coefficients and mean transverse momentum to the quadrupole deformation and system-size in isotopic Xe-Xe collisions. Flow observables strongly depend on the strength of nucleon-nucleon scattering occuring in even-A and odd-A nuclei. Flow for odd-A nuclei is suppressed in comparison to flow in even-A collisions. There exists a linear inter-dependence between $p_{T}$ integrated anisotropic flow and nuclear deformation. Mean transverse momentum signifies the fireball temperature in body-body and tip-tip collisions. There exists a negative linear correlation of $⟨ p_{T} ⟩$ with collision system-size and a positive correlation with nuclear deformation. Flow measurements in high-energy, heavy-ion collisions using isotopic collision systems, offer a new precision tool to study nuclear structure physics. Observation of nuclear structure properties like nuclear deformation in a heavy-ion collision such as this would be very interesting.
Comments:
10 pages, 10 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2312.05853 [pdf]
EPJC(2024)·0 citations
11
[Submitted on 10 Dec 2023] (cross-list from hep-ph)
Critical dynamics within the real-time fRG approach
Yong-rui Chen🇨🇳 · Yang-yang Tan🇨🇳 · Wei-jie Fu🇨🇳
The Schwinger-Keldysh functional renormalization group (fRG) developed in [1] is employed to investigate critical dynamics related to a second-order phase transition. The effective action of model A is expanded to the order of $O (\partial^{2})$ in the derivative expansion for the $O (N)$ symmetry. By solving the fixed-point equations of effective potential and wave function, we obtain static and dynamic critical exponents for different values of the spatial dimension $d$ and the field component number $N$ . It is found that one has $z \geq 2$ in the whole range of $2 \leq d \leq 4$ for the case of $N = 1$ , while in the case of $N = 4$ the dynamic critical exponent turns to $z < 2$ when the dimension approach towards $d = 2$ .
Comments:
11 pages, 11 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2312.05870 [pdf]
PRD(2024)·9 citations
12
[Submitted on 10 Dec 2023] (cross-list from hep-ph)
An Effective Field Theory study of medium heavy quark evolution
Miguel Ángel Escobedo🇪🇸
The evolution of hard probes in a medium is a complex multiscale problem that significantly benefits from the use of Effective Field Theories (EFTs). Within the EFT framework, we aim to define a series of EFTs in a way that addresses each energy scale individually in separate steps. However, studying hard probes in a medium presents challenges. This is because an EFT is typically constructed by formulating the most general Lagrangian compatible with the problem's symmetries. Nevertheless, medium effects may not always be encoded adequately in an effective action. In this paper, we construct an EFT that is valid for studying the evolution of a heavy quark in a QCD plasma containing few other heavy quarks, where degrees of freedom with an energy of the order of the temperature scale are integrated out. Through this example, we explicitly demonstrate how to handle the doubling of degrees that arise in non-equilibrium field theory. As a result, we derive a Fokker-Planck equation using only symmetry and power counting arguments. The methods introduced in this paper will pave the way for future developments in the study of quarkonium suppression.
Comments:
34 pages. Matches published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2312.05901 [pdf]
Universe(2024)·0 citations
13
[Submitted on 11 Dec 2023] (cross-list from hep-th)
Rotating gluon system and confinement
Yin Jiang🇨🇳
In this work the non-abelian gauge theory is reformulated in a local inertial frame with the presence of a background rotation. With this new formalism the influence of the background rotation on the color deconfinement transition for a SU(2) pure gluon system. The KvBLL caloron, which is a color neutral and asymptotically nontrivial solution of Yang-Mills equation at finite temperature, is adopted to confine the color charges. With new solutions of the caloron's constituent particles, i.e. dyons, the semi-classical potential, which confines color charges, and the perturbative potential, induced by the Gaussian fluctuation, have been obtained for this system under rotation. By solving the critical temperature of confinement-deconfinement phase transition in different computation schemes, it is found that neither the rotational semi-classical potential nor Gaussian fluctuations can confine color charges more tightly when the rotation becomes faster. While only a stronger coupling constant is able to make the critical temperature increasing with angular velocity, as that indicated in lattice simulations. And it is also found with some particular sets of parameters, a non-monotonic dependence of the critical temperature will be obtained in the most physically realistic case, in which all the three factors are taken into account.
Comments:
9 pages, 4 figures
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2312.06166 [pdf]
PLB(2024)·23 citations

Affiliations

first authorsco-authorsvia INSPIRE