Nuclear Theory·nucl-th

Friday·July 2, 2021

11 papers—5 primary·6 cross-listed

01
[Submitted on 1 Jul 2021]
Hyperon Dynamics in Heavy-ion Collisions near threshold energy
Ding-Chang Zhang🇨🇳 · Hui-Gan Cheng🇨🇳 · Zhao-Qing Feng🇨🇳
Within the framework of quantum molecular dynamics transport model, the isospin and in-medium effects on the hyperon production in the reaction of $^{197}$ Au + $^{197}$ Au are investigated thoroughly. A repulsive hyperon-nucleon potential from the chiral effective field theory is implemented into the model, which is related to the hyperon momentum and baryon density. The correction on threshold energy of the elementary hyperon cross section is taken into account. It is found that the $Σ$ yields are suppressed in the domain of midrapidity and kinetic energy spectra with the potential. The hyperons are emitted in the reaction plane because of the strangeness exchange reaction and reabsorption process in nuclear medium. The $Σ^{-} / Σ^{+}$ ratio depends on the stiffness of nuclear symmetry energy, in particular in the high-energy region (above 500 MeV).
Comments:
5 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2107.00277 [pdf]
Chin.Phys.Lett.(2021)·16 citations
02
[Submitted on 1 Jul 2021]
Nuclear Structure at the Crossroads
R.J. Furnstahl🇺🇸 · H.-W. Hammer🇩🇪 · A. Schwenk🇩🇪
Steven Weinberg's seminal papers from 1990-92 initiated the use of effective field theories (EFTs) for nuclei. We summarize progress, priorities, and open questions for nuclear EFT developments based on the 2019 INT program "Nuclear Structure at the Crossroads."
Comments:
15 pages, Contribution to Special Issue: Celebrating 30 years of Steven Weinberg's papers on Nuclear Forces from Chiral Lagrangians; published version
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2107.00413 [pdf]
Few Body Syst.(2021)·16 citations
03
[Submitted on 1 Jul 2021]
Eccentricities, fluctuations and A-dependence of elliptic and triangular flows in heavy-ion collisions
G.Kh. Eyyubova🇷🇺 · V.L. Korotkikh🇷🇺 · A.M. Snigirev🇷🇺 · E.E. Zabrodin🇷🇺
A simple geometrical model with event-by-event fluctuations is suggested to study elliptical and triangular eccentricities in the initial state of relativistic heavy-ion collisions. This model describes rather well the ALICE and ATLAS data for Pb+Pb collisions at center-of-mass energy $s_{N N} = 5.02$ ~TeV per nucleon pair, assuming that the second, $v_{2}$ , and third, $v_{3}$ , harmonics of the anisotropic flow are simply linearly proportional to the eccentricities $ε_{2}$ and $ε_{3}$ , respectively. We show that the eccentricity $ε_{3}$ has a pure fluctuation origin and is substantially dependent on the size of the overlap area only, while the eccentricity $ε_{2}$ is mainly related to the average collision geometry. Elliptic flow, therefore, is weakly dependent on the event-by-event fluctuations everywhere except of the very central collisions 0--2%, whereas triangular flow is mostly determined by the fluctuations. The scaling dependence of the magnitude of the flow harmonics on atomic number, $v_{n} \propto A^{- 1/3}$ , is predicted for this centrality interval.
Comments:
Further development and extension of ideas discussed in arXiv:2007.04850. Accepted for publication in J. of Physics G: Nucl. and Part. Physics
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2107.00521 [pdf]
J.Phys.G(2021)·9 citations
04
[Submitted on 29 Jun 2021]
Diffusion as a possible mechanism controlling the production of superheavy nuclei in cold fusion reactions
T. Cap · M. Kowal · K. Siwek-Wilczyńska
The fusion probability for the production of superheavy nuclei in cold fusion reactions was investigated and compared with recent experimental results for $^{48}$ Ca, $^{50}$ Ti, and $^{54}$ Cr incident on a $^{208}$ Pb target. Calculations were performed within the fusion-by-diffusion model (FbD) using new nuclear data tables by Jachimowicz et al. It is shown that the experimental data could be well explained within the framework of the FbD model. The saturation of the fusion probability at bombarding energies above the interaction barrier is reproduced. It emerges naturally from the physical effect of the suppression of contributions of higher partial waves in fusion reactions and is related to the critical angular momentum. The role of the difference in values of the rotational energies in the fusion saddle point and contact (sticking) configuration of the projectile-target system is discussed.
Comments:
submitted to PLB
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2107.00579 [pdf]
PRC(2022)·9 citations
05
[Submitted on 1 Jul 2021]
Constraining the hadronic spectrum and repulsive interactions in a hadron resonance gas via fluctuations of conserved charges
Jamie M. Karthein🇺🇸 · Volker Koch🇺🇸 · Claudia Ratti🇺🇸 · Volodymyr Vovchenko🇺🇸
We simultaneously incorporate two common extensions of the hadron resonance gas model, namely the addition of extra, unconfirmed resonances to the particle list and the excluded volume repulsive interactions. We emphasize the complementary nature of these two extensions and identify combinations of conserved charge susceptibilities that allow to constrain them separately. In particular, ratios of second-order susceptibilities like $χ_{11}^{B Q} / χ_{2}^{B}$ and $χ_{11}^{B S} / χ_{2}^{B}$ are sensitive only to the baryon spectrum, while fourth-to-second order ratios like $χ_{4}^{B} / χ_{2}^{B}$ , $χ_{31}^{B S} / χ_{11}^{B S}$ , or $χ_{31}^{B Q} / χ_{11}^{B Q}$ are mainly determined by repulsive interactions. Analysis of the available lattice results suggests the presence of both the extra states in the baryon-strangeness sector and the repulsive baryonic interaction, with indications that hyperons have a smaller repulsive core than non-strange baryons. The modified hadron resonance gas model presented here significantly improves the description of lattice QCD susceptibilities at chemical freeze-out and can be used for the analysis of event-by-event fluctuations in heavy-ion collisions.
Comments:
10 pages, 5 figures, version published in Phys. Rev. D
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2107.00588 [pdf]
PRD(2021)·28 citations
06
[Submitted on 29 Jun 2021] (cross-list from hep-ph)
Degeneracy patterns of chiral companions at finite temperature
Juan M. Torres-Rincon🇩🇪
Chiral symmetry represents a fundamental concept lying at the core of particle and nuclear physics. Its spontaneous breaking in vacuum can be exploited to distinguish chiral hadronic partners, whose masses differ. In fact, the features of this breaking serve as guiding principles for the construction of effective approaches of QCD at low energies, e.g., the chiral perturbation theory, the linear sigma model, the (Polyakov)--Nambu--Jona-Lasinio model, etc. At high temperatures/densities chiral symmetry can be restored bringing the chiral partners to be nearly degenerated in mass. At vanishing baryochemical potential, such restoration follows a smooth transition, and the chiral companions reach this degeneration above the transition temperature. In this work I review how different realizations of chiral partner degeneracy arise in different effective theories/models of QCD. I distinguish the cases where the chiral states are either fundamental degrees of freedom or (dynamically-generated) composed states. In particular, I discuss the intriguing case in which chiral symmetry restoration involves more than two chiral partners, recently addressed in the literature.
Comments:
34 pages, 12 figures. Published version in Symmetry journal, Special Issue "Advances on Chiral Symmetry and Its Restoration". Typos corrected and new references added
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2106.15700 [pdf]
Symmetry(2021)·5 citations
07
[Submitted on 30 Jun 2021] (cross-list from hep-ph)
Radiative corrections for factorized jet observables in heavy ion collisions
Varun Vaidya🇺🇸
I look at the renormalization of the medium structure function and a medium induced jet function in a factorized cross section for jet substructure observables in Heavy Ion collisions. This is based on the formalism developed in \cite{Vaidya:2020lih}, which uses an Open quantum system approach combined with the Effective Field Theory(EFT) for forward scattering to derive a factorization formula for jet observables which work as hard probes of a long lived dilute Quark Gluon Plasma(QGP) medium. I show that the universal medium structure function that captures the observable independent physics of the QGP has both UV and rapidity anomalous dimensions that appear due to medium induced Bremsstrahlung. The resulting Renormalization Group(RG) equations correspond to the BFKL equation and the running of the QCD coupling respectively. I present the first results for the numerical impact of resummation using these RG equations on the mean free path of the jet in the medium. I also briefly discuss the prospects of extending this formalism for a short lived dense medium.
Comments:
35 pages, 8 Figures, some updated discussion
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2107.00029 [pdf]
JHEP(2024)·14 citations
08
[Submitted on 1 Jul 2021] (cross-list from hep-ph)
Proton number cumulants and correlation functions in Au-Au collisions at $s_{NN} = 7.7 - 200$ GeV from hydrodynamics
Volodymyr Vovchenko🇺🇸 · Volker Koch🇺🇸 · Chun Shen🇺🇸
We present a dynamical description of (anti)proton number fluctuations cumulants and correlation functions in central Au-Au collisions at $s_{NN} = 7.7 - 200$ GeV by utilizing viscous hydrodynamics simulations. The cumulants of proton and baryon number are calculated in a given momentum acceptance analytically, via an appropriately extended Cooper-Frye procedure describing particlization of an interacting hadron resonance gas. The effects of global baryon number conservation are taken into account using a generalized subensemble acceptance method. The experimental data of the STAR collaboration are consistent at $s_{NN} ≳ 20$ GeV with simultaneous effects of global baryon number conservation and repulsive interactions in baryon sector, the latter being in line with the behavior of baryon number susceptibilities observed in lattice QCD. The data at lower collision energies show possible indications for sizable attractive interactions among baryons. The data also indicate sizable negative two-particle correlations between antiprotons that are not satisfactorily described by baryon conservation and excluded volume effects. We also discuss differences between cumulants and correlation functions (factorial cumulants) of (anti)proton number distribution, proton versus baryon number fluctuations, and effects of hadronic afterburner.
Comments:
18 pages, 12 figures, published in Physical Review C
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2107.00163 [pdf]
PRC(2022)·100 citations
09
[Submitted on 1 Jul 2021] (cross-list from hep-ph)
Treating divergence in quark matter by using energy projectors
Guojun Huang🇨🇳 · Pengfei Zhuang🇨🇳
We calculate gluon self-energy using quark energy projectors in a general quark-gluon plasma. By separating the quark field into a positive- and a negative-energy mode, the quark loop constructed with the same mode is always convergent, and the divergence appears only in the mixed loop with different modes and is medium independent. After removing the divergence in vacuum, we obtain the one-loop gluon self-energy at finite temperature, chemical potential and quarks mass without approximation. With the method of quark loop resummation, we calculate non-perturbatively the gluon Debye mass and thermodynamic potential. In the limit of small gluon momentum in comparison with temperature, chemical potential and quark mass, our calculation comes back to the known HTL/HDL results in literature.
Comments:
10 pages, 2 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2107.00276 [pdf]
PRD(2021)·6 citations
10
[Submitted on 1 Jul 2021] (cross-list from nucl-ex)
First observation of high- $K$ isomeric states in $^{249}$ Md and $^{251}$ Md
T. Goigoux🇫🇷 · Ch. Theisen🇫🇷 · B. Sulignano🇫🇷 · M. Airiau🇫🇷 · K. Auranen🇫🇮 · H. Badran🇫🇮 · R. Briselet🇫🇷 · T. Calverley🇫🇮 · D. Cox🇫🇮 · F. Déchery🇫🇷 · F. Defranchi Bisso🇫🇮 · A. Drouart🇫🇷 and 36 other authors
Decay spectroscopy of the odd-proton nuclei $^{249}$ Md and $^{251}$ Md has been performed. High- $K$ isomeric states were identified for the first time in these two nuclei through the measurement of their electromagnetic decay. An isomeric state with a half-life of $2.8 (5)$ ms and an excitation energy $\geq 910$ keV was found in $^{249}$ Md. In $^{251}$ Md, an isomeric state with a half-life of $1.4 (3)$ s and an excitation energy $\geq 844$ keV was found. Similarly to the neighbouring $^{255}$ Lr, these two isomeric states are interpreted as 3 quasi-particle high- $K$ states and compared to new theoretical calculations. Excited nuclear configurations were calculated within two scenarios: via blocking nuclear states located in proximity to the Fermi surface or/and using the quasiparticle Bardeen-Cooper-Schrieffer method. Relevant states were selected on the basis of the microscopic-macroscopic model with a deformed Woods-Saxon potential. The most probable candidates for the configurations of $K$ -isomeric states in Md nuclei are proposed.
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2107.00517 [pdf]
EPJA(2021)·13 citations
11
[Submitted on 1 Jul 2021] (cross-list from hep-ph)
The unfinished fabric of the three neutrino paradigm
Francesco Capozzi🇺🇸 · Eleonora Di Valentino🇬🇧 · Eligio Lisi🇮🇹 · Antonio Marrone🇮🇹 · Alessandro Melchiorri🇮🇹 · Antonio Palazzo🇮🇹
In the current 3nu paradigm, flavor oscillations probe 3 mixing angles (theta_12, theta_23, theta_13), one CP phase delta, and two squared mass differences delta m^2>0 and Delta m^2, where sign(Delta m^2)=+ (-) for normal (inverted) ordering. Absolute nu masses can be probed by the effective m_beta in beta decay, by the total mass Sigma in cosmology and, if neutrinos are Majorana, by another effective m_{beta beta} in 0nu2beta decay. Within an updated global analysis of (non)oscillation data, we constrain these 3nu parameters, both separately and in selected pairs, and highlight the concordance or discordance among different constraints. Five oscillation parameters (delta m^2, Delta m^2, theta_12, theta_23, theta_13) are consistently measured, with an overall accuracy ranging from ~1% for Delta m^2 to ~6% for sin^2(theta_23) (due to its octant ambiguity). We find overall hints for normal ordering (at 2.5 sigma), as well as for theta_23<pi/4 and for sin(delta)<0 (both at 90% C.L.), and discuss some tensions among datasets. Concerning nonoscillation data, we include the recent KATRIN constraints on m_beta, and we combine the latest 76-Ge, 130-Te and 136-Xe bounds on m_{beta beta}, accounting for NME covariances. We also discuss some variants related to CMB anisotropy and lensing data, which may affect cosmological constraints on Sigma and hints on sign(Delta m^2). The default option, including all Planck results, irrespective of the lensing anomaly, sets upper bounds on Sigma at the level of ~10^-1 eV, and further favors normal ordering up to ~3 sigma. An alternative option, that includes recent ACT results + other independent results (from WMAP and selected Planck data) globally consistent with standard lensing, is insensitive to the ordering but prefers Sigma ~(few) x 10^-1 eV, with different implications for m_beta and m_{beta beta} searches. (Abridged)
Comments:
22 pages, including 16 figures. Revised text with minor additions and corrections; results unchanged. To appear in PRD
Subjects:
High Energy Physics — Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2107.00532 [pdf]
PRD(2021)·295 citations

Affiliations

first authorsco-authorsvia INSPIRE