Nuclear Theory·nucl-th

Friday·August 7, 2020

10 papers—5 primary·5 cross-listed

01
[Submitted on 5 Aug 2020]
Effects of QCD critical point on light nuclei production
Kai-Jia Sun🇺🇸 · Che Ming Ko🇨🇳 · Feng Li🇺🇸
Using the nucleon coalescence model, which can naturally take into account the correlations in the nucleon density distribution, we study the effects of QCD critical point on light nuclei production in relativistic heavy-ion collisions. We find that the yield ratio $N_{t} N_{p} / N_{d}^{2}$ of proton ( $p$ ), deuteron ( $d$ ) and triton ( $t$ ) increases monotonically with the nucleon density correlation length, which is expected to increase significantly near the critical point in the QCD phase diagram. Our study thus demonstrates that the yield ratio $N_{t} N_{p} / N_{d}^{2}$ can be used as a sensitive probe of the QCD critical phenomenon. We further discuss the relation between the QCD phase transitions in heavy-ion collisions and the possible non-monotonic behavior of \pdt~in its collision energy dependence.
Comments:
6 pages, 1 figure
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2008.02325 [pdf]
PLB(2021)·27 citations
02
[Submitted on 6 Aug 2020]
Pseudospin symmetry and octupole correlations for multiple chiral doublets in 131Ba
Y. P. Wang🇨🇳 · Y. Y. Wang🇨🇳 · J. Meng🇨🇳
A reflection-asymmetric triaxial particle rotor model with three quasiparticles and a reflection-asymmetric triaxial rotor is developed, and applied to investigate the observed multiple chiral doublets (Mḩi}D) candidates with octupole correlations in 131Ba, i.e., two pairs of positive-parity bands D3-D4 and D5-D6, as well as one pair of negative-parity bands D7-D8. The energy spectra, the energy staggering parameters, the B(M1)/B(E2) ratios, and the B(E1)/B(E2) ratios are reproduced well. The chiral geometries for these Mḩi}D candidates are examined by the azimuthal plots, and the evolution of chiral geometry with spin is clearly demonstrated. The intrinsic structure for the positive-parity bands is analyzed and the possible pseudospin-chiral quartet bands are suggested.
Comments:
16 pages, 8 figures, PHYSICAL REVIEW C (in press)
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2008.02414 [pdf]
PRC(2020)·24 citations
03
[Submitted on 6 Aug 2020]
Shape Coexistence in Hot Rotating 100 Nb
Mamta Aggarwal
Temperature and angular momentum induced shape changes in the well deformed 100 Nb have been investigated within the theoretical framework of Statistical theory combined with triaxially deformed Nilson potential and Strutinsky prescription. Two shape coexistence, one in the ground state of 104 Nb between oblate and triaxial shapes and another one between oblate and rarely seen prolate non-collective shapes in excited hot rotating 100 Nb at the mid spin values around 14-16h are reported for the first time. The level density parameter indicates the influence of the shell effects and changes drastically at the shape transition. The band crossing is observed at the sharp shape transition.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2008.02602 [pdf]
0 citations
04
[Submitted on 6 Aug 2020]
Shape Transition to a Rare Shape Phase of Prolate Non-collective in A = 100 Isobars
Mamta Aggarwal
A theoretical investigation on the shape transitions with neutron number, temperature and spin for A $=$ 100 isobars of Z $=$ 42 to 50 is presented. A variety of shape transitions are observed while moving from neutron rich 100 Mo to proton rich 100 Sn with predominant triaxial shapes. Temperature and spin induced shape transitions are explored within the microscopic theoretical framework of and statistical theory of hot rotating nuclei. Prolate non-collective which is a rare shape phase is reported in this mass region on the proton rich side of the nuclear chart.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2008.02611 [pdf]
0 citations
05
[Submitted on 6 Aug 2020]
Investigation of Quark Distributions in a Family of Pentaquarks using the Thomas-Fermi Quark Model
Mohan Giri🇺🇸 · Suman Baral🇳🇵 · Gopi C. Kaphle🇳🇵 · Nirmal Dangi🇳🇵 · Sudip Shiwakoti🇺🇸 · Leonardo Bardomero🇺🇸 · Paul Lashomb🇺🇸 · Walter Wilcox🇺🇸
Using the Thomas-Fermi quark model, a collective, spherically symmetric density of states is created to represent a gas of interacting fermions with various degeneracies at zero temperature. Over a family of multi-pentaquarks, color interaction probabilities are obtained after averaging over all the possible configurations. It is found that three different Thomas-Fermi functions are necessary for light, charm, and anti-charm quarks. These are assumed to be linearly related by proportionality constants resulting in consistency conditions. We analyze these conditions and find that they lead to an interesting pattern of spherical quark distributions.
Comments:
16 pages, 2 figures, EVIST collaboration
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2008.02677 [pdf]
Commun.Theor.Phys.(2021)·2 citations
06
[Submitted on 5 Aug 2020] (cross-list from astro-ph.HE)
Black Dwarf Supernova in the Far Future
M. E. Caplan
In the far future long after star formation has ceased the universe will be populated by sparse degenerate remnants, mostly white dwarfs, though their ultimate fate is an open question. These white dwarfs will cool and freeze solid into black dwarfs while pycnonuclear fusion will slowly process their composition to iron-56. However, due to the declining electron fraction the Chandrasekhar limit of these stars will be decreasing and will eventually be below that of the most massive black dwarfs. As such, isolated dwarf stars with masses greater than $\sim 1.2 M_{⊙}$ will collapse in the far future due to the slow accumulation of iron-56 in their cores. If proton decay does not occur then this is the ultimate fate of about $1 0^{21}$ stars, approximately one percent of all stars in the observable universe. We present calculations of the internal structure of black dwarfs with iron cores as a model for progenitors. From pycnonuclear fusion rates we estimate their lifetime and thus delay time to be $1 0^{1100}$ years. We speculate that high mass black dwarf supernovae resemble accretion induced collapse of O/Ne/Mg white dwarfs while later low mass transients will be similar to stripped-envelope core-collapse supernova, and may be the last interesting astrophysical transients to occur prior to heat death.
Comments:
6 pages, 1 figure, accepted for publication in MNRAS
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2008.02296 [pdf]
MNRAS(2020)·7 citations
07
[Submitted on 6 Aug 2020] (cross-list from hep-ph)
Centrality, transverse momentum and collision energy dependence of the Tsallis parameters in relativistic heavy-ion collisions
Rajendra Nath Patra🇺🇦 · Bedangadas Mohanty🇮🇳 · Tapan K. Nayak🇨🇭
The thermodynamic properties of matter created in high-energy heavy-ion collisions have been studied in the framework of the non-extensive Tsallis statistics. The transverse momentum ( $p_{T}$ )~spectra of identified charged particles (pions, kaons, protons) and all charged particles from the available experimental data of Au-Au collisions at the Relativistic Heavy Ion Collider (RHIC) energies and Pb-Pb collisions at the Large Hadron Collider (LHC) energies are fitted by the Tsallis distribution. The fit parameters, $q$ and $T$ measure the degree of deviation from an equilibrium state and the effective temperature of the thermalized system, respectively. The $p_{T}$ ~spectra are well described by the Tsallis distribution function from peripheral to central collisions for the wide range of collision energies, from $s_{NN}$ = 7.7 GeV to 5.02 TeV. The extracted Tsallis parameters are found to be dependent on the particle species, collision energy, centrality, and fitting ranges in $p_{T}$ . For central collisions, both $q$ and $T$ depend strongly on the fit ranges in $p_{T}$ . For most of the collision energies, $q$ remains almost constant as a function of centrality, whereas $T$ increases from peripheral to central collisions. For a given centrality, $q$ systematically increases as a function of collision energy whereas $T$ has a decreasing trend. A profile plot of $q$ and $T$ with respect to collision energy and centrality shows an anti-correlation between the two parameters.
Comments:
12 pages, 10 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2008.02559 [pdf]
Eur.Phys.J.Plus(2021)·25 citations
08
[Submitted on 6 Aug 2020] (cross-list from hep-ph)
Correlating $h \to μ^{+} μ^{-}$ to the Anomalous Magnetic Moment of the Muon via Leptoquarks
Andreas Crivellin🇨🇭 · Dario Mueller🇨🇭 · Francesco Saturnino🇨🇭
Recently, both ATLAS and CMS measured the decay $h \to μ^{+} μ^{-}$ , finding a signal strength with respect to the Standard Model expectation of $1.2 \pm 0.6$ and $1.19 + 0.41 + 0.17 - 0.39 - 0.16$ , respectively. This provides, for the first time, evidence that the Standard Model Higgs couples to second generation fermions. This measurement is particularly interesting in the context of the intriguing hints for lepton flavor universality violation, accumulated within recent years, as new physics explanations could also be tested in the $h \to μ^{+} μ^{-}$ decay mode. Leptoquarks are prime candidates to account for the flavor anomalies. In particular, they can provide the necessary chiral enhancement (by a factor $m_{t} / m_{μ}$ ) to address $a_{μ}$ with TeV scale new physics. In this letter we point out that such explanations of $a_{μ}$ also lead to enhanced effects in $h \to μ^{+} μ^{-}$ and we examine the correlations between $h \to μ^{+} μ^{-}$ and $a_{μ}$ within leptoquark models. We find that the effect in the branching ratio of $h \to μ^{+} μ^{-}$ ranges from several percent up to a factor three, if one aims at accounting for $a_{μ}$ at the $2 σ$ level. Hence, the new ATLAS and CMS measurements already provide important constraints on the parameter space, rule out specific $a_{μ}$ explanations and will be very important to test the flavor anomalies in the future.
Comments:
8 pages, 3 figures, g-2 updated, EFT discussion added, version accepted for publication in PRL
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2008.02643 [pdf]
PRL(2021)·83 citations
09
[Submitted on 6 Aug 2020] (cross-list from hep-ph)
Relativistic Friedrichs-Lee model and quark-pair creation model
Zhi-Yong Zhou🇨🇳 · Zhiguang Xiao🇨🇳
In this paper, we present how the Friedrichs-Lee model could be extended to the relativistic scenario and be combined with the relativistic quark pair creation model in a consistent way. This scheme could be applied to study the "unquenched" effect of the meson spectra. As an example, if the lowest $J^{P C} = 0^{++}$ $(u u ˉ + d d ˉ) / 2$ bound state in the potential model is coupled to the $π π$ continuum, two resonance poles could be found from the scattering amplitude for the continuum states. One of them could correspond to the $f_{0} (500) / σ$ and the other probably $f_{0} (1370)$ . This scheme might shed more light on why extra states could appear in the hadron spectrum other than the prediction of the quark potential model.
Comments:
v3, figure 3 added, some discussions added, published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2008.02684 [pdf]
EPJC(2020)·14 citations
10
[Submitted on 5 Aug 2020] (cross-list from hep-ph)
Neutron star structure with nuclear force mediated by hypothetical X17 boson
Vlasios Petousis🇨🇿 · Martin Veselsky🇨🇿 · Jozef Leja🇸🇰
A reported $17$ MeV boson, which has been proposed as an explanation to the $^{8}$ Be and $^{4}$ He anomaly, is investigated in the context of its possible influence to neutron stars structure. Implementing a $m_{X}$ =17 MeV to the nuclear equation of state using different incompressibility values K $_{0}$ =245 MeV and K $_{0}$ =260 MeV and solving Tolman-Oppenheimer-Volkoff equations, we estimate an upper limit of $M_{T O V} \approx 2.4 M ⊙$ for a non rotating neutron star with span in radius $R$ between $11.5$ km to $14$ km. Moving away from pure - NN with admixture of 10\% protons and simulating possible softening of equation of state due to hyperons, we see that our estimated limits fit quite well inside the newest reported studies, coming from neutron stars merger event, GW190814
Comments:
5 pages, 4 figures, To appear in the EPJ Web of Conferences
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2008.02733 [pdf]
EPJ Web Conf.(2021)·5 citations

Affiliations

first authorsco-authorsvia INSPIRE