Nuclear Theory·nucl-th

Tuesday·June 14, 2022

12 papers—6 primary·6 cross-listed

07
Open Bottom Mesons and Upsilon States in Hot Magnetized Strange Hadronic Matter
Amal Jahan C.S.🇮🇳 · Amruta Mishra🇮🇳
The masses of open bottom mesons ( $B$ ( $B^{+}$ , $B^{0}$ ), $B ˉ$ ( $B^{-}$ , $B^{0} ˉ$ ), $B_{s}$ ( $B_{s}^{0}$ , $B_{s}^{0} ˉ$ )) and upsilon states ( $Υ (1 S)$ , $Υ (2 S)$ , $Υ (3 S)$ , $Υ (4 S)$ , and $Υ (1 D)$ ) are investigated in the isospin asymmetric strange hadronic medium at finite temperature in the presence of strong magnetic fields using a chiral effective Lagrangian approach. For charged baryons, the magnetic field introduces contribution from Landau energy levels. The masses of the open bottom mesons get modified through their interactions with the baryons and the scalar mesons, which undergo modifications in a magnetized medium. The charged open bottom mesons have additional positive mass shifts due to Landau quantization in the presence of the magnetic field. The medium mass shift of the upsilon states originates from the modification of the gluon condensates simulated by the variation of dilaton field ( $χ$ ) and a quark mass term in the magnetized medium. The open bottom mesons and upsilon states experience a mass drop in the magnetized medium. The masses of these mesons initially increase with a rise in temperature, and beyond a high value of temperature, their masses are observed to drop. When the temperature is below 90 MeV, the in-medium masses of the mesons increase with an increase in the magnetic field. However, at high temperatures (T $>$ 90 MeV), the masses are observed to drop with an increase in the magnetic field. The dominant in-medium effects are the density effects, which can have observable effects in asymmetric heavy-ion collisions planned at compressed baryonic matter experiments at FAIR at the future facility of GSI.
↳ hep-phnucl-thIJMPE(2022)·5 citations
08
Scaling Properties of the $Δ γ$ Correlator: Constraints on Background and CME-Sensitive Charge Separation in Heavy-Ion Collisions
Roy A. Lacey (1) · Niseem Magdy (2) ((1) Depts. of Chemistry and Physics, Stony Brook University, Stony Brook, New York 11794, USA (2) Dept. of Physics, Texas Southern University, Houston, TX 77004, USA)
The scaling properties of the $Δ γ$ correlator are used to investigate charge separation associated with the chiral magnetic effect (CME) in $p$ +Au, $d$ +Au, Ru+Ru, Zr+Zr, and Au+Au collisions at $s_{NN} = 200$ ~GeV, and in $p$ +Pb and Pb+Pb collisions at $s_{NN} = 5.02$ and $2.76$ ~TeV. Anomalous Viscous Fluid Dynamics (AVFD) calculations provide complementary benchmarks for background and signal+background behavior. Scaling $Δ γ$ by the elliptic-flow coefficient $v_{2}$ reduces the leading flow-coupled background dependence, while the resulting $Δ γ / v_{2}$ exhibits a common approximate $1/ N_{ch}$ scaling behavior for $p$ +Au, $d$ +Au, $p$ +Pb, and Pb+Pb collisions, consistent with multiplicity dilution of background-driven charge correlations across markedly different collision systems and environments. In contrast, Ru+Ru, Zr+Zr, and Au+Au collisions exhibit systematic positive deviations from their respective $1/ N_{ch}$ background-scaling trends. These scaling violations are qualitatively similar to those generated by AVFD calculations with an input CME signal and, relative to the experimentally constrained background scaling, provide evidence for a CME contribution to the measured charge separation. The inferred CME fraction is approximately $27%$ for mid-central Au+Au collisions and roughly a factor of two smaller for Ru+Ru and Zr+Zr, whose values are consistent within uncertainties. The inferred CME fractions reduce the expected Ru+Ru--Zr+Zr difference to only $\sim 1.3%$ in the total charge-separation signal, explaining its limited experimental sensitivity. These results demonstrate that scaling violations relative to an experimentally constrained background provide a quantitative strategy for isolating a CME contribution to charge separation in heavy-ion collisions.
↳ nucl-exhep-exnucl-th7 citations
09
Leading order, next-to-leading order, and non-perturbative parton collision kernels: effects in static and evolving media
Rouzbeh Modarresi Yazdi🇨🇦 · Shuzhe Shi🇨🇦 · Charles Gale🇨🇦 · Sangyong Jeon🇨🇦
Energetic partons traveling in a strongly interacting medium lose energy by emitting radiation and through collisions with medium constituents. Non-perturbative, next-to-leading order and leading order collision kernels are implemented within AMY-McGill formalism. The resulting gluon emission rates are then evaluated and compared by considering scattering occurring in a brick of quark-gluon plasma, as well as in a realistic simulation of Pb-Pb, collisions at $s = 2.76$ ATeV using MARTINI. We find that the variations in quenching of hard partons resulting from using different kernels can be important, depending on the overall value of the strong coupling constant $α_{s}$ .
↳ hep-phnucl-thPRC(2022)·16 citations
10
Relativistic spin dynamics for vector mesons
Xin-Li Sheng🇨🇳 · Lucia Oliva🇮🇹 · Zuo-Tang Liang🇨🇳 · Qun Wang🇨🇳 · Xin-Nian Wang🇺🇸
We propose a relativistic theory for spin density matrices of vector mesons based on Kadanoff-Baym equations in the closed-time-path formalism. The theory puts the calculation of spin observables such as the spin density matrix element $ρ_{00}$ for vector mesons on a solid ground. Within the theory we formulate $ρ_{00}$ for $ϕ$ mesons into a factorization form in separation of momentum and space-time variables. We argue that the main contribution to $ρ_{00}$ at lower energies should be from the $ϕ$ fields that can polarize the strange quark and antiquark in the same way as electromagnetic fields. The key observation is that there is correlation inside the $ϕ$ meson wave function between the $ϕ$ field that polarizes the strange quark and that polarizes the strange antiquark. This is reflected by the fact that the contributions to $ρ_{00}$ are all in squares of fields which are nonvanishing even if the fields may strongly fluctuate in space-time. The fluctuation of strong force fields can be extracted from $ρ_{00}$ of quarkonium vector mesons as links to fundamental properties of quantum chromodynamics.
↳ hep-phnucl-thPRD(2024)·71 citations
11
Constraints on key $^{17}$ O( $α, γ$ ) $^{21}$ Ne resonances and impact on the weak s-process
M. Williams · A.M. Laird · A. Choplin · P. Adsley · B. Davids · U. Greife · K. Hudson · D. Hutcheon · A. Lennarz · C. Ruiz
The efficiency of the slow neutron-capture process in massive stars is strongly influenced by neutron-capture reactions on light elements. At low metallicity, $^{16}$ O is an important neutron absorber, but the effectiveness of $^{16}$ O as a light-element neutron poison is modified by competition between subsequent $^{17}$ O $(α, n)^{20}$ Ne and $^{17}$ O $(α, γ)^{21}$ Ne reactions. The strengths of key $^{17}$ O $(α, γ)^{21}$ Ne resonances within the Gamow window for core helium burning in massive stars are not well constrained by experiment. This work presents more precise measurements of resonances in the energy range $E_{c . m .} = 612 - 1319$ keV. We extract resonance strengths of $ω γ_{638} = 4.85 \pm 0.79$ $μ$ eV, $ω γ_{721} = 13. 0_{- 2.4}^{+ 3.3}$ $μ$ eV, $ω γ_{814} = 7.72 \pm 0.55$ meV and $ω γ_{1318} = 136 \pm 13$ meV, for resonances at $E_{c . m .} =$ 638, 721, 814 and 1318 keV, respectively. We also report an upper limit for the 612 keV resonance of $ω γ < 140$ neV ( $95%$ c.l.), which effectively rules out any significant contribution from this resonance to the reaction rate. From this work, a new $^{17}$ O $(α, γ)^{21}$ Ne thermonuclear reaction rate is calculated and compared to the literature. The effect of present uncertainties in the $^{17}$ O $(α, γ)^{21}$ Ne reaction rate on weak s-process yields are then explored using post-processing calculations based on a rotating $20 M_{⊙}$ low-metallicity massive star. The resulting $^{17}$ O $(α, γ)^{21}$ Ne reaction rate is lower with respect to the pre-existing literature and found to enhance weak s-process yields in rotating massive star models.
↳ nucl-exastro-ph.SRnucl-thPRC(2022)·5 citations
12
Subleading contributions to $N$ -boson systems inside the universal window
Paolo Recchia🇫🇷 · Alejandro Kievsky🇮🇹 · Luca Girlanda🇮🇹 · Mario Gattobigio🇫🇷
We study bosonic systems in the regime in which the two-body system has a shallow bound state or, equivalently, a large value of the two-body scattering length. Using the effective field theory framework as a guide, we construct a series of potential terms which have decreasing importance in the description of the binding energy of the systems. The leading order potential terms consist of a two-body term, usually attractive, plus a three-body term, usually repulsive; this last term is required to prevent the collapse of systems with more than two particles. At this order, the parametrization of the two-body potential is done to obtain a correct description of the scattering length, which governs the dynamics in this regime, whereas the three-body term fixes a three-body datum. We investigate the role of the cut-off in the leading order description and we extend the exploration beyond the leading order by including the next-to-leading order terms in both, the two- and three-body potentials. We use the requirement of the stability of the N-body system, whose energy is variationally estimated, to introduce the three-body forces. The potential parametrization, as a function of the cut-off, is fixed to describe the energy of 4 He clusters up to seven particles within the expected accuracy. Finally, we also explore the possibility to describe at the same time the atom-dimer scattering length.
↳ physics.atom-phnucl-thPRA(2022)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE

Open Bottom Mesons and Upsilon States in Hot Magnetized Strange Hadronic Matter

Scaling Properties of the Δγ Correlator: Constraints on Background and CME-Sensitive Charge Separation in Heavy-Ion Collisions

Leading order, next-to-leading order, and non-perturbative parton collision kernels: effects in static and evolving media

Relativistic spin dynamics for vector mesons

Constraints on key 17O(α,γ)21Ne resonances and impact on the weak s-process

Subleading contributions to N-boson systems inside the universal window

Affiliations

Scaling Properties of the $Δ γ$ Correlator: Constraints on Background and CME-Sensitive Charge Separation in Heavy-Ion Collisions

Constraints on key $^{17}$ O( $α, γ$ ) $^{21}$ Ne resonances and impact on the weak s-process

Subleading contributions to $N$ -boson systems inside the universal window