Nuclear Theory·nucl-th

Tuesday·September 27, 2022

13 papers—6 primary·7 cross-listed

01
[Submitted on 24 Sept 2022]
Anisotropic flows of charmonium in the relativistic heavy-ion collisions
Chenyu Li🇺🇸 · Baoyi Chen🇨🇳
We review recent studies about anisotropic flows ( $v_{1}, v_{2}, v_{3}$ ) of charmonium in the quark-gluon plasma produced in relativistic heavy-ion collisions. Collective flows of the bulk medium are developed due to the anisotropic pressure gradient of the medium. Strongly coupled with the bulk medium, charm quarks carry collective flows from the expanding medium, which will be inherited by the regenerated charmonium via the coalescence process. In event-by-event collisions where nucleon positions fluctuate from the smooth distribution, there is triangularity in the medium initial energy density. Triangular flows of the bulk medium and heavy flavor particles can be developed due to the initial fluctuations. In the longitudinal direction, the rapidity-odd distribution of the initial energy density is induced by the rotation of the medium in non-central heavy-ion collisions. Charmonium suffers biased dissociation along positive and negative $x$ -directions in forward (backward) rapidity. The directed flow of charmonium becomes non-zero. The directed, elliptic and triangular flows ( $v_{1}, v_{2}, v_{3}$ ) of charmonium come from the anisotropic initial distributions of the medium energy density in the transverse and longitudinal directions.
Comments:
12pages, 10 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2209.11996 [pdf]
Mathematics(2022)·1 citation
02
[Submitted on 24 Sept 2022]
Threshold photoproduction of neutral pions off protons in nuclear model with explicit mesons
D. V. Fedorov🇩🇰 · M. Mikkelsen🇨🇭
We apply the nuclear model with explicit mesons to photoproduction of neutral pions off protons at the threshold. In this model the nucleons do not interact with each other via a potential but rather emit and absorb mesons that are treated explicitly on equal footing with the nucleons. We calculate the total cross section of the reaction for energies close to threshold and compare the calculations with available experimental data. We show that the model is able to reproduce the experimental data and determine the range of the parameters where the model is compatible with the experiment.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2209.12071 [pdf]
Few Body Syst.(2023)·3 citations
03
[Submitted on 25 Sept 2022]
Model study on $Υ (n S)$ modification in small collision systems
Junlee Kim🇰🇷 · Jinjoo Seo🇰🇷 · Byungsik Hong🇰🇷 · Juhee Hong🇰🇷 · Eun-Joo Kim🇰🇷 · Yongsun Kim🇰🇷 · MinJung Kweon🇰🇷 · Su Houng Lee🇰🇷 · Sanghoon Lim🇰🇷 · Jaebeom Park🇰🇷
Quarkonium production has been studied extensively in relativistic heavy-ion collision experiments to understand the properties of the quark gluon plasma. The experimental results on the yield modification in heavy-ion collisions relative to that in $p$ + $p$ collisions can be described by several models considering dissociation and regeneration effects. A yield modification beyond initial-state effects has also been observed in small collision systems such as $p$ +Au and $p$ +Pb collisions, but it is still premature to claim any hot medium effect. A model study in various small collision systems such as $p$ + $p$ , $p$ +Pb, $p$ +O, and O+O collisions will help quantitatively understanding nuclear effects on the $Υ (n S)$ production. A theoretical calculation considering the gluo-dissociation and inelastic parton scattering and their inverse reaction reasonably describes the suppression of $Υ (1 S)$ in Pb+Pb collisions. Based on this calculation, a Monte-Carlo simulation is developed to more realistically incorporate the medium produced in heavy-ion collisions with event-by-event initial collision geometry and hydrodynamic evolution. We extend this framework to small systems to study the medium effects. In this work, we quantify the nuclear modification factor of $Υ (n S)$ as a function of charged particle multiplicity ( $d N_{c h} / d η$ ) and transverse momentum. We also calculate the elliptic flow of $Υ (n S)$ in small collision systems.
Comments:
11 pages, 12 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2209.12303 [pdf]
PRC(2023)·11 citations
04
[Submitted on 26 Sept 2022]
Spin Boltzmann equation for non-relativistic spin-1/2 fermions
Wen-Bo Dong🇨🇳 · Yi-Liang Yin🇨🇳 · Qun Wang🇨🇳
We derive the spin Boltzmann equations for spin-1/2 fermions in a non-relativistic model with four-fermion contact interaction which conserves spin degrees of freedom. A great advantage of the model is that the spin matrix elements in collision terms can be completely worked out and be put into such a compact form that one can clearly see how spins are coupled in particle scatterings. A semi-classical expansion in the Planck constant has been made and the on-shell part of the spin Boltzmann equation up to the next-to-leading order is derived. At the leading order the equilibrium spin distribution can be obtained from the vanishing of the collision term for the spin density. The spin chemical potential emerges as a natural consequence of spin conservation. The off-shell part of the spin Boltzmann equation is also discussed. The work can be extended to more sophisticated interaction such as nuclear force in order to apply to spin polarization phenomena in heavy-ion collisions at low energies.
Comments:
RevTex 4, 15 pages, 1 figure
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2209.12402 [pdf]
PRC(2022)·4 citations
05
[Submitted on 26 Sept 2022]
Systematic study of proton radioactivity half-lives based on the relationship between the Skyrme-Hartree-Fock and the macroscopic quantities of nuclear matter
Jun-Hao Cheng · Zhen Zhang · Xi-Jun Wu · Peng-Cheng Chu · Xiao-Hua Li
In the present work, we systematically study the proton radioactivity half-lives of 33 spherical nuclei based on the relationship between the Skyrme parameters and the macroscopic quantities of nuclear matter. Using the two-potential approach with the spherical Skyrme-Hartree-Fock model, the correlation between proton radioactivity half-life and macroscopic quantities was analyzed. Moreover, we obtained a new Skyrme parameter set by fitting the two most weighted macroscopic quantities. Compared with Skyrme parameters MSL0 and the theoretical model of proton radioactivity UDLP, the theoretical proton radioactivity half-life calculated by the new Skyrme parameter set can better reproduce the experimental data.
Comments:
8 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2209.12615 [pdf]
CPC(2022)·2 citations
06
[Submitted on 26 Sept 2022]
Role of vector self-interaction in Neutron Star properties
Bikram Keshari Pradhan · Debarati Chatterjee · Radhika Gandhi · Jürgen Schaffner-Bielich
Previous studies have claimed that there exist correlations among certain nuclear saturation parameters and neutron star observables, such as the slope of the symmetry energy and the radius of a $1.4 M_{⊙}$ neutron star. However, it is not clear whether such correlations are physical or spurious, as they are not observed universally for all equation of state models. In this work, we probe the role of vector self-interaction within the framework of the Relativistic Mean Field model and its role in governing the observable stellar properties and their correlations with nuclear parameters. We confirm that the effect of this term is not only to control the high density properties of the equation of state but also to govern such correlations. We also impose a limit on the maximum strength of the vector self-interaction using recent astrophysical data.
Comments:
14 pages, 10 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
2209.12657 [pdf]
NPA(2023)·42 citations
07
[Submitted on 22 Sept 2022] (cross-list from hep-th)
Stability of multi-component relativistic viscous hydrodynamics from Israel-Stewart and reproducing DNMR from maximizing the entropy
Dekrayat Almaalol🇺🇸 · Travis Dore🇺🇸 · Jacquelyn Noronha-Hostler🇺🇸
The Quark Gluon Plasma produced in heavy-ion collisions has three relevant conserved charges: baryon number (B), strangeness (S), and electric charge (Q). Here we derive the Israel-Stewart framework for BSQ diffusion coupled to shear and bulk viscosity and the thermodynamic derivatives needed to couple this to a BSQ equation of state. We reproduce a subset of the $J$ terms in the DNMR approach and propose a technique to derive other terms from the maximum entropy principle. Finally, we preform a stability analysis that can be used to constraint transport coefficients in BSQ hydrodynamics.
Comments:
24 pages, 0 figures
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2209.11210 [pdf]
PRD(2025)·26 citations
08
[Submitted on 24 Sept 2022] (cross-list from hep-lat)
Determination of Lattice QCD Equation of state at a finite chemical potential
Sabarnya Mitra🇮🇳
Exponential resummation to all orders in $μ_{B}$ is a promising scheme which can capture contributions to all orders in $μ_{B}$ by considering only the first few Taylor coefficients in the Taylor expansion of thermodynamic observables in lattice QCD. This approach however, gets affected by biased estimates of $n$ -point correlation functions $D_{n}$ whose effects can significantly hinder probe of finite density QCD. We present an unbiased exponential resummation formalism, which can reproduce the Taylor series up to the desired order in $μ_{B}$ , besides retaining the original form of the all-order resummation estimate of QCD partition function.
Comments:
6 pages, 2 figures, Contribution to 25th DAE BRNS Symposium 12-16 December 2022
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2209.11937 [pdf]
Springer Proc.Phys.(2024)·5 citations
09
[Submitted on 24 Sept 2022] (cross-list from nucl-ex)
Higher-Order Cumulants and Correlation Functions of Proton Multiplicity Distributions in $s_{NN}$ = 3 GeV Au+Au Collisions at the RHIC STAR Experiment
STAR Collaboration: M. S. Abdallah · B. E. Aboona · J. Adam · L. Adamczyk · J. R. Adams · J. K. Adkins · I. Aggarwal · M. M. Aggarwal · Z. Ahammed · D. M. Anderson · E. C. Aschenauer · J. Atchison and 361 other authors
We report a measurement of cumulants and correlation functions of event-by-event proton multiplicity distributions from fixed-target Au+Au collisions at $s_{NN}$ = 3 GeV measured by the STAR experiment. Protons are identified within the rapidity ( $y$ ) and transverse momentum ( $p_{T}$ ) region $- 0.9 < y < 0$ and $0.4 < p_{T} < 2.0$ GeV/ $c$ in the center-of-mass frame. A systematic analysis of the proton cumulants and correlation functions up to sixth-order as well as the corresponding ratios as a function of the collision centrality, $p_{T}$ , and $y$ are presented. The effect of pileup and initial volume fluctuations on these observables and the respective corrections are discussed in detail. The results are compared to calculations from the hadronic transport UrQMD model as well as a hydrodynamic model. In the most central 5\% collisions, the value of proton cumulant ratio $C_{4} / C_{2}$ is negative, drastically different from the values observed in Au+Au collisions at higher energies. Compared to model calculations including Lattice QCD, a hadronic transport model, and a hydrodynamic model, the strong suppression in the ratio of $C_{4} / C_{2}$ at 3 GeV Au+Au collisions indicates an energy regime dominated by hadronic interactions.
Comments:
25 pages, 20 figures, 4 tables
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2209.11940 [pdf]
PRC(2023)·69 citations
10
[Submitted on 25 Sept 2022] (cross-list from nucl-ex)
An Indirect Measurement of $^{6}$ Li(n, $γ$ ) Cross Sections
Midhun C.V · M.M Musthafa · S.V Suryanarayana · Gokuldas H · Shaima A · Hajara. K · Antony Joseph · T. Santhosh · A. Baishya · A Pal · P.C Rout · S Santra and 5 other authors
The $^{6}$ Li(n, $γ$ ) $^{7}$ Li cross sections in the neutron energy range of 0.6 to 4 MeV have been measured by the experimental implementation of the direct capture formalism. This was done by measuring the $γ$ transition probability experimentally and accounting for the spin factor by theoretical calculation. The electromagnetic transition probabilities from $^{7}$ Li $^{*}$ analogous to the initial neutron capture states of $^{6}$ Li $+ n$ were measured by populating the J $_{i}$ states of $^{7}$ Li through $^{7}$ Li( $p, p^{'}$ ) $^{7}$ Li $^{*}$ reaction. The impact of coupling of resonant states, above neutron separation threshold of $^{7}$ Li, in the neutron capture, is observed from the capture $γ$ spectrum. The measured cross sections were reproduced through {\sc fresco} and Talys-1.95 Direct Capture Calculations.
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2209.12165 [pdf]
3 citations
11
[Submitted on 26 Sept 2022] (cross-list from hep-ph)
Kaon spectrum revisited
U. Taboada-Nieto🇪🇸 · P.G. Ortega🇪🇸 · D.R. Entem🇪🇸 · F. Fernández🇪🇸 · J. Segovia🇪🇸
The European Organization for Nuclear Research (CERN) has recently approved a world-unique QCD facility in which an updated version of the external M2 beam line of the CERN SPS in conjunction with a universal spectrometer of the COMPASS experiment is used. One of its main goals is to use highly intense and energetic kaon beams to map out the complete spectrum of excited kaons with an unprecedented precision; having a broad impact not only on low-energy QCD phenomenology, but also on many high-energy particle processes where excited kaons appear, such as the study of CP violation in heavy-meson decays studied at LHCb and Belle~II. In support of the experimental effort, the kaon spectrum is computed herein using a constituent quark model which has been successfully applied to a wide range of hadronic observables, from light to heavy quark sectors, and thus the model parameters are completely constrained. The model's prediction can be used as a template against which to compare the already collected data and future experimental findings, in order to distinguish between conventional and exotic kaon states. We also compare our results with those available in the literature in order to provide some general statements, common to all calculations.
Comments:
11 pages, 1 figure, 13 tables
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2209.12555 [pdf]
EPJA(2023)·13 citations
12
[Submitted on 26 Sept 2022] (cross-list from hep-lat)
Lattice regularizations of $θ$ vacua: Anomalies and qubit models
Mendel Nguyen🇺🇸 · Hersh Singh🇺🇸
Anomalies are a powerful way to gain insight into possible lattice regularizations of a quantum field theory. In this work, we argue that the continuum anomaly for a given symmetry can be matched by a manifestly-symmetric, local, lattice regularization in the same spacetime dimensionality only if (i) the symmetry action is offsite, or (ii) if the continuum anomaly is reproduced exactly on the lattice. We consider lattice regularizations of a class of prototype models of QCD: the (1+1)-dimensional asymptotically-free Grassmannian nonlinear sigma models (NLSMs) with a $θ$ term. Using the Grassmannian NLSMs as a case study, we provide examples of lattice regularizations in which both possibilities are realized. For possibility (i), we argue that Grassmannian NLSMs can be obtained from $SU (N)$ antiferromagnets with a well-defined continuum limit, reproducing both the infrared physics of $θ$ vacua and the ultraviolet physics of asymptotic freedom. These results enable the application of new classical algorithms to lattice Monte Carlo studies of these quantum field theories, and provide a viable realization suited for their quantum simulation. On the other hand, we show that, perhaps surprisingly, the conventional lattice regularization of $θ$ vacua due to Berg and Lüscher reproduces the anomaly exactly on the lattice, providing a realization of the second possibility.
Comments:
10 pages + appendices
Subjects:
High Energy Physics — Lattice (hep-lat); Strongly Correlated Electrons (cond-mat.str-el); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2209.12630 [pdf]
PRD(2023)·10 citations
13
[Submitted on 26 Sept 2022] (cross-list from astro-ph.HE)
The Radius of PSR J0740+6620 from NICER with NICER Background Estimates
Tuomo Salmi🇳🇱 · Serena Vinciguerra🇳🇱 · Devarshi Choudhury🇳🇱 · Thomas E. Riley🇳🇱 · Anna L. Watts🇳🇱 · Ronald A. Remillard🇺🇸 · Paul S. Ray🇺🇸 · Slavko Bogdanov🇺🇸 · Sebastien Guillot🇫🇷 · Zaven Arzoumanian🇺🇸 · Cecilia Chirenti🇺🇸 · Alexander J. Dittmann🇺🇸 and 6 other authors
We report a revised analysis for the radius, mass, and hot surface regions of the massive millisecond pulsar PSR J0740+6620, studied previously with joint fits to NICER and XMM-Newton data by Riley et al. (2021) and Miller et al. (2021). We perform a similar Bayesian estimation for the pulse-profile model parameters, except that instead of fitting simultaneously the XMM-Newton data, we use the best available NICER background estimates to constrain the number of photons detected from the source. This approach eliminates any potential issues in the cross-calibration between these two instruments, providing thus an independent check of the robustness of the analysis. The obtained neutron star parameter constraints are compatible with the already published results, with a slight dependence on how conservative the imposed background limits are. A tighter lower limit causes the inferred radius to increase, and a tighter upper limit causes it to decrease. We also extend the study of the inferred emission geometry to examine the degree of deviation from antipodality of the hot regions. We show that there is a significant offset to an antipodal spot configuration, mainly due to the non-half-cycle azimuthal separation of the two emitting spots. The offset angle from the antipode is inferred to be above 25 degrees with 84% probability. This seems to exclude a centered-dipolar magnetic field in PSR J0740+6620.
Comments:
29 pages, 18 figures (10 of which are figure sets), 1 animation, 10 tables. Published in ApJ
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)
arXiv:
2209.12840 [pdf]
ApJ(2022)·128 citations

Affiliations

first authorsco-authorsvia INSPIRE