Nuclear Theory·nucl-th

Wednesday·February 7, 2024

12 papers—4 primary·8 cross-listed

01
[Submitted on 5 Feb 2024]
Exploring freeze out and flow using exact solutions of conformal hydrodynamics
Owen Bradley🇺🇸 · Christopher Plumberg🇺🇸
Exact solutions to the equations of hydrodynamics provide valuable benchmark tests for numerical hydrodynamic codes and also provide useful insights into the nature of hydrodynamic flow. In this paper, we introduce two novel, closely related exact solutions with non-trivial rapidity dependence which are generalizations of the well-known Gubser flow solution to conformal hydrodynamics. We then use one of our solutions to explore the consequences of choosing between two different criteria for implementing the freeze out process in fluid dynamical simulations of nuclear collisions: freeze out at constant temperature vs. freeze out at constant Knudsen number. We find that, employing our exact solution, the differences between these freeze out criteria are heavily influenced by the presence of strong collective flow. Our results highlight the importance of accurately describing the freeze out process in collisions with large flow gradients, particularly in small systems.
Comments:
18 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Theory (hep-th); Nuclear Experiment (nucl-ex)
arXiv:
2402.03568 [pdf]
PRC(2024)·2 citations
02
[Submitted on 6 Feb 2024]
The spin alignment of rho mesons in a pion gas
Yi-Liang Yin🇨🇳 · Wen-Bo Dong🇨🇳 · Jin-Yi Pang🇨🇳 · Shi Pu🇨🇳 · Qun Wang🇨🇳
We study the spin alignment of neutral rho mesons in a pion gas using spin kinetic or Boltzmann equations. The $ρ π π$ coupling is given by the chiral effective theory. The collision terms at the leading and next-to-leading order in spin Boltzmann equations are derived. The evolution of the spin density matrix of the neutral rho meson is simulated with different initial conditions. The numerical results show that the interaction of pions and neutral rho mesons creates very small spin alignment in the central rapidity region if there is no rho meson in the system at the initial time. Such a small spin alignment in the central rapidity region will decay rapidly toward zero in later time. If there are rho mesons with a sizable spin alignment at the initial time the spin alignment will also decrease rapidly. We also considered the effect on $ρ_{00}$ from the elliptic flow of pions in the blast wave model. With vanishing spin alignment at the initial time, the deviation of $ρ_{00}$ from 1/3 is positive but very small.
Comments:
RevTex 4, 17 pages, 12 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2402.03672 [pdf]
PRC(2024)·10 citations
03
[Submitted on 6 Feb 2024]
On the calculation and use of effective single-particle energies. The example of the neutron $1 d_{3/2}$ - $1 d_{5/2}$ splitting along $N = 20$ isotones
Vittorio Somà🇫🇷 · Thomas Duguet🇫🇷
The rich phenomenology of quantum many-body systems such as atomic nuclei is complex to interpret. Often, the behaviour (e.g. evolution with the number of constituents) of measurable/observable quantities such as binding or excitation energies can be best understood on the basis of a simplified picture involving auxiliary quantities that are not observable, i.e. whose values vary with parameters that are internal to the theoretical construction (contrarily to measurable/observable quantities). While being useful, the simplified interpretation is thus theoretical-scheme-dependent. This applies, in particular, to the so-called single-nucleon shell structure based on auxiliary effective single-particle energies (ESPEs). In this context, the present work aims at (i) recalling the way to compute ESPEs out of solutions of many-body Schrödinger's equation, (ii) illustrating the use of ESPEs within the frame of state-of-the-art ab initio calculations to interpret the outcome of a recent nuclear experiment and (iii) demonstrating the impact of several alterations to the computation of ESPEs. While the chosen alterations constitute approximations within the ab initio scheme, they are built-in when employing other theoretical constructs at play in nuclear physics. The present considerations are thus meant to empirically illustrate variations that can be expected between ESPEs computed within different (equally valid) theoretical schemes.
Comments:
13 pages, 7 figures, accepted for publication in Phil. Trans. R. Soc. A
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2402.03854 [pdf]
Phil.Trans.A.Math.Phys.Eng.Sci.(2024)·4 citations
04
[Submitted on 6 Feb 2024]
Nuclear Isomers at the Extremes of their Properties
Bhoomika Maheshwari · Ashok Kumar Jain
The longer-lived excited nuclear states, referred as nuclear isomers, exist due to the hindered decays owing to their peculiar nucleonic structural surroundings. Some of these conditions, being exceptionally rare and limited to achieve, elevate certain isomers to the status of extreme and unusual isomers among their kin. For example, the $E 5$ coupling of single-particle orbitals is rare and so are $E 5$ decaying isomers. This review delves into some of such remarkable isomers scattered across the nuclear landscape while highlighting the possibilities to find more of them. Unique properties of some of them, harbor the potential for transformative applications in medicine and energy. An exciting example is that of the lowest energy isomer known so far in $^{229}$ Th, which may help realize the dream of an ultra-precise nuclear clock in the coming decade. These isomers also offer an insight into the extremes of nuclear structure associated with them, which leads to their unusual status in energy, half-life, spin etc. The review attempts to highlight isomers with high-multipolarities, high-spins, high-energies, longest half-lives, extremely low energy, etc. A lack of theoretical understanding of the decay rates, half-lives and moments of these isomers is also pointed out.
Comments:
To appear in the special issue on Nuclear Isomers in Euro. Phys. Jour. ST
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2402.03976 [pdf]
Eur.Phys.J.ST(2024)·2 citations
05
[Submitted on 5 Feb 2024] (cross-list from hep-ph)
Probing Earth-Bound Dark Matter with Nuclear Reactors
Yohei Ema🇺🇸 · Maxim Pospelov🇺🇸 · Anupam Ray🇺🇸
Strongly-interacting dark matter can be accumulated in large quantities inside the Earth, and for dark matter particles in a few GeV mass range, it can exist in large quantities near the Earth's surface. We investigate the constraints imposed on such dark matter properties by its upscattering by fast neutrons in nuclear reactors with subsequent scattering in nearby well-shielded dark matter detectors, schemes which are already used for searches of the coherent reactor neutrino scattering. We find that the existing experiments cover new parameter space on the spin-dependent interaction between dark matter and the nucleon. Similar experiments performed with research reactors, and lesser amount of shielding, may provide additional sensitivity to strongly-interacting dark matter.
Comments:
16 pages, 4 figures; v2: version accepted in JHEP
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2402.03431 [pdf]
JHEP(2024)·13 citations
06
[Submitted on 5 Feb 2024] (cross-list from hep-ph)
Measuring jet energy loss fluctuations in the quark-gluon plasma via multiparticle correlations
Abraham Holtermann · Jacquelyn Noronha-Hostler · Anne M. Sickles · Xiaoning Wang
The quark-gluon plasma (QGP) is a high temperature state of matter produced in the collisions of two nuclei at relativistic energies. The properties of this matter at short distance scales are probed using jets with high transverse momentum ( $p_{T}$ ) resulting from quarks and gluons scattered with large momentum transfer in the earliest stages of the collisions. The Fourier harmonics for anisotropies in the high transverse momentum particle yield, $v_{n} (p_{T})$ , indicate the path length dependence of jet energy loss within the QGP. We present a framework to build off of measurements of jet energy loss using $v_{n} (p_{T})$ by characterizing fluctuations in jet energy loss that are currently not constrained experimentally. In this paper, we utilize a set of multivariate moments and cumulants as new experimental observables to measure event-by-event fluctuations in the azimuthal anisotropies of rare probes, and compare them to the azimuthal anisotropies of soft particles. Ultimately, these fluctuations can be used to quantify the magnitude and fluctuations of event-by-event jet energy loss. We relate these quantities to existing multivariate cumulant observables, highlight their unique properties, and validate their sensitivities with a Monte Carlo simulation.
Comments:
25 pages, 11 figures, 4 tables
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2402.03512 [pdf]
5 citations
07
[Submitted on 6 Feb 2024] (cross-list from hep-ph)
Charmed hadron chemistry and flow in heavy and light ion collisions at the LHC
Yu-Fei Liu · Wen-Jing Xing · Xiang-Yu Wu · Shanshan Cao · Guang-You Qin · Shu-Qing Li
We study the charmed meson and baryon production and elliptic flow in ultra-relativistic nucleus-nucleus collisions at the LHC energies. The space-time evolution of quark-gluon plasma (QGP) produced in these energetic collisions is obtained via the (3+1)-dimensional CLVisc hydrodynamics model, the heavy quark dynamics inside the QGP is simulated using an improved Langevin model that incorporates both elastic and inelastic parton energy loss processes, and the heavy quark hadronization is simulated utilizing a comprehensive coalescence-fragmentation model. Using our combined approach, we first calculate charmed hadron ratios, $Λ_{c} / D^{0}$ and $D_{s} / D^{0}$ , as well as their elliptic flow ( $v_{2}$ ) as a function of transverse momentum ( $p_{T}$ ) for different centralities in Pb+Pb collisions at $s_{N N} = 5.02$ ~TeV. Due to strangeness enhancement and parton coalescence effects, $D_{s} / D^{0}$ and $Λ_{c} / D^{0}$ ratios increase from peripheral to central collisions, and such centrality dependence for $Λ_{c} / D^{0}$ is stronger than $D_{s} / D^{0}$ . We further predict the $p_{T}$ and centrality dependences of charmed hadron chemistry and $v_{2}$ in smaller Xe+Xe, Ar+Ar and O+O collisions at the LHC energies. Strong centrality and system size dependences for $Λ_{c} / D^{0}$ and $D_{s} / D^{0}$ ratios are observed across four collision systems. As for charmed hadron flow, both system size and collision geometry are important to understand the centrality dependence of $v_{2}$ in different collision systems. Our study provides a significant reference for studying heavy quark evolution and hadronizaiton in large and small systems in relativistic nuclear collisions.
Comments:
12 pages, 10 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2402.03622 [pdf]
1 citation
08
[Submitted on 6 Feb 2024] (cross-list from hep-ph)
On the non-universality of heavy quark hadronization in elementary high-energy collisions
Yuxuan Dai🇨🇳 · Shouxing Zhao🇨🇳 · Min He🇨🇳
It has been traditionally hypothesized that the heavy quark (charm, $c$ and bottom, $b$ ) fragmentation is universal across different collision systems, based on the notion that hadronization as a soft process should occur at the characteristic non-perturbative QCD scale, $Λ_{QC D}$ . However, this universality hypothesis has recently been challenged by the observation that the $c$ - and $b$ -baryon production relative to their meson counterparts in minimum bias proton-proton ( $pp$ ) collisions at the LHC energies is significantly enhanced as compared to the electron-positron ( $e^{+} e^{-}$ ) collisions. The conception of non-universality is unambiguously reinforced by the latest measurement of the charged-particle multiplicity dependence of the $b$ -baryon-to-meson yield ratio, $Λ_{b} / B$ , by the LHCb experiment in $s = 13$ \,TeV $pp$ collisions at the LHC, evolving continuously from the saturation value in minimum bias $pp$ collisions toward the small value in $e^{+} e^{-}$ collisions as the system size gradually reduces. We address the multiplicity dependence of $b$ -baryon production in the canonical statistical hadronization model with input $b$ -hadron spectrum augmented with many hitherto unobserved states from quark model predictions. We demonstrate that the decreasing trend of the $Λ_{b} / B$ toward low multiplicities can be quantitatively understood from the canonical suppression on the yield of $Λ_{b}$ , as caused by the requirement of strict conservation of baryon number in sufficiently small systems. We have therefore proposed a plausible scenario for understanding the origin of the non-universality of heavy quark fragmentation in elementary collisions.
Comments:
6 pages, 3 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2402.03692 [pdf]
PRC(2024)·6 citations
09
[Submitted on 6 Feb 2024] (cross-list from gr-qc)
Twin Stars in General Relativity and Extended Theories of Gravity
Eva Lope-Oter🇪🇸 · Aneta Wojnar🇪🇸
We explore gravity-independent equations of state for neutron stars, particularly focusing on twin stars. Examining four categories, we emphasize their behavior in both General Relativity and Palatini gravity. Additionally, we discuss a subcategory of type I, which, in the context of General Relativity, does not exhibit twin star phenomena, yet demonstrates this phenomenon in modified gravity. Furthermore, we briefly address challenges associated with the negative trace of the energy-momentum tensor, prevalent in both theories.
Comments:
21 pages, 14 figures, 5 tables
Subjects:
General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2402.03914 [pdf]
JCAP(2025)·9 citations
10
[Submitted on 6 Feb 2024] (cross-list from astro-ph.HE)
From existing and new nuclear and astrophysical constraints to stringent limits on the equation of state of neutron-rich dense matter
Hauke Koehn🇩🇪 · Henrik Rose🇩🇪 · Peter T. H. Pang🇳🇱 · Rahul Somasundaram🇺🇸 · Brendan T. Reed🇺🇸 · Ingo Tews🇺🇸 · Adrian Abac🇩🇪 · Oleg Komoltsev🇳🇴 · Nina Kunert🇩🇪 · Aleksi Kurkela🇳🇴 · Michael W. Coughlin🇺🇸 · Brian F. Healy🇺🇸 · Tim Dietrich🇩🇪
Through continuous progress in nuclear theory and experiment and an increasing number of neutron-star observations, a multitude of information about the equation of state (EOS) for matter at extreme densities is available. To constrain the EOS across its entire density range, this information needs to be combined consistently. However, the impact and model-dependency of individual observations vary. We present a broad compendium of different constraints and apply them individually to a large set of EOS candidates within a Bayesian framework. Specifically, we explore different ways how chiral effective field theory and perturbative quantum chromodynamics can be used to place a likelihood on EOS candidates. We also investigate the impact of nuclear experimental constraints, as well as different radio and X-ray observations of neutron star (NS) masses and radii. This is augmented by reanalyses of the existing data from BNS coalescences, in particular of GW170817, with improved models for the tidal waveform and kilonova light curves, which we also utilize to construct a tight upper limit of 2.39M $_{⊙}$ on the TOV mass based on GW170817's remnant. Our diverse set of constraints is eventually combined to obtain stringent limits on NS properties. We organize the combination in a way to distinguish between constraints where the systematic uncertainties are deemed small and those that rely on less conservative assumptions. For the former, we find the radius of the canonical 1.4M $_{⊙}$ neutron star to be $R_{1.4} = 12.2 6_{- 0.91}^{+ 0.80}$ km and the TOV mass at $M_{TOV} = 2.2 5_{- 0.22}^{+ 0.42}$ M $_{⊙}$ (95% credibility). Including all the presented constraints yields $R_{1.4} = 12.2 0_{- 0.48}^{+ 0.50}$ km and $M_{TOV} = 2.3 0_{- 0.20}^{+ 0.07}$ M $_{⊙}$ .
Comments:
55 pages, 33 figures, webinterface for custom constraint combinations in https://multi-messenger.physik.uni-potsdam.de/eos_constraints/
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2402.04172 [pdf]
PRX(2025)·138 citations
11
[Submitted on 6 Feb 2024] (cross-list from hep-ph)
Probing the internal structures of $p Ω$ and $ΩΩ$ with their production at the LHC
Jie Pu🇨🇳 · Kai-Jia Sun🇨🇳 · Chun-Wang Ma🇨🇳 · Lie-Wen Chen🇨🇳
The strange dibaryons $p Ω$ ( $^{5} S_{2}$ ) and $ΩΩ$ ( $^{1} S_{0}$ ) are likely bound, existing either in molecular states like the deuteron or as more exotic compact six-quark states. Here, we investigate the production of these two dibaryons in Pb+Pb collisions at $s_{N N}$ =2.76 TeV at the CERN Large Hadron Collider (LHC) within a covariant coalescence model, which employs a blast-wave-like parametrization for the phase-space configurations of constituent particles at freeze-out. For the molecular states, the $p Ω$ and $ΩΩ$ are produced via $p$ - $Ω$ and $Ω$ - $Ω$ coalescence, respectively, while for the six-quark states, they are formed through $uu d sss$ and $ssssss$ coalescence. We find that the yield ratio $N_{p Ω} / N_{Ω}$ and $N_{ΩΩ} / N_{Ω}$ have a distinct centrality dependence between the molecular and multi-quark states, thus offering a promising way for distinguishing the two states. Our results suggest that the measurements of $p Ω$ and $ΩΩ$ production in relativistic heavy-ion collisions can shed light on their internal structures.
Comments:
6 pages, 3 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2402.04185 [pdf]
PRC(2024)·7 citations
12
[Submitted on 6 Feb 2024] (cross-list from hep-lat)
Classical and Quantum Computing of Shear Viscosity for $2 + 1 D$ SU(2) Gauge Theory
Francesco Turro🇺🇸 · Anthony Ciavarella🇺🇸 · Xiaojun Yao🇺🇸
We perform a nonperturbative calculation of the shear viscosity for $(2 + 1)$ -dimensional SU(2) gauge theory by using the lattice Hamiltonian formulation. The retarded Green's function of the stress-energy tensor is calculated from real time evolution via exact diagonalization of the lattice Hamiltonian with a local Hilbert space truncation, and the shear viscosity is obtained via the Kubo formula. When taking the continuum limit, we account for the renormalization group flow of the coupling but no additional operator renormalization. We find the ratio of the shear viscosity and the entropy density $\frac{η}{s}$ is consistent with a well-known holographic result $\frac{1}{4 π}$ at several temperatures on a $4 \times 4$ honeycomb lattice with the local electric representation truncated at $j_{max} = \frac{1}{2}$ . We also find the ratio of the spectral function and frequency $\frac{ρ ^{x y} ( ω )}{ω}$ exhibits a peak structure when the frequency is small. Both the exact diagonalization method and simple matrix product state classical simulation method beyond $j_{max} = \frac{1}{2}$ on bigger lattices require exponentially growing resources. So we develop a quantum computing method to calculate the retarded Green's function and analyze various systematics of the calculation including $j_{max}$ truncation and finite size effects, Trotter errors and the thermal state preparation efficiency. Our thermal state preparation method still requires resources that grow exponentially with the lattice size, but with a very small prefactor at high temperature. We test our quantum circuit on both the Quantinuum emulator and the IBM simulator for a small lattice and obtain results consistent with the classical computing ones.
Comments:
21 pages, 19 figures; v2: added a discussion on matching; v3: added a subsection on thermal state preparation, published version
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2402.04221 [pdf]
PRD(2024)·69 citations

Affiliations

first authorsco-authorsvia INSPIRE