Nuclear Theory·nucl-th

Tuesday·February 28, 2023

16 papers—4 primary·12 cross-listed

05
Finite volume effects in the extended linear sigma model via low momentum cutoff
Győző Kovács🇭🇺 · Péter Kovács🇭🇺 · Pok Man Lo🇵🇱 · Krzysztof Redlich🇵🇱 · György Wolf🇭🇺
Contrary to field theoretical calculations in the thermodynamic limit where the volume is assumed to be infinitely large, the heavy-ion collisions always carry the effects of finite size. A sufficiently small system size is expected to affect the thermodynamic quantities and the phase diagram of the strongly interacting matter. To study these effects one can take into account the finite spatial extent of the system within the framework of an effective model too, via the restriction of the momentum integrals using discretization or in a simplified case using a low momentum cutoff. We investigated the effects of the finite volume in a vector meson extended Polyakov quark-meson model and found a remarkable change in the thermodynamics and the phase transition, especially in the location of the critical endpoint.
↳ hep-phnucl-thPoS(2023)·5 citations
06
Radiative decays of the spin- $2$ partner of $X (3872)$
Pan-Pan Shi🇨🇳 · Jorgivan M. Dias🇨🇳 · Feng-Kun Guo🇨🇳
It has been generally expected that the $X (3872)$ has a spin-2 partner, $X_{2}$ , with quantum numbers $J^{P C} = 2^{++}$ . In the hadronic molecular model, its mass was predicted to be below the $D^{*} D ˉ^{*}$ threshold, and the new structure reported in the $γ ψ (2 S)$ invariant mass distribution by the Belle Collaboration with mass $M = (4014.3 \pm 4.0 \pm 1.5)$ MeV and decay width $Γ = (4 \pm 11 \pm 6)$ MeV, with a global significance of 2.8 $σ$ , is a nice candidate for it. We consider the radiative decay widths for the $X_{2} \to γ ψ$ with $ψ = J / ψ, ψ (2 S)$ treating the $X_{2}$ as a $D^{*} D ˉ^{*}$ shallow bound state, and estimate the events of $X_{2}$ in two-photon collisions that can be collected in the $γ J / ψ \to γ ℓ^{+} ℓ^{-}$ ( $ℓ = e, μ$ ) final states at Belle. Based on the upper limit for the ratio of decay widths of $X (3872) \to γ ψ (2 S)$ and $X (3872) \to γ J / ψ$ measured by BESIII, we predict the similar ratio $Γ (X_{2} \to γ ψ (2 S)) /Γ (X_{2} \to γ J / ψ)$ to be smaller than $1.0$ . We suggest searching for the $X_{2}$ signal in the $γ J / ψ$ invariant mass distribution via two-photon fusions. The results will lead to insights into both the $X (3872)$ and the new structure observed by Belle.
↳ hep-phhep-exnucl-exnucl-thPLB(2023)·19 citations
07
Effect of time-varying electromagnetic field on Wiedemann-Franz law in a hot hadronic matter
Kamaljeet Singh🇮🇳 · Jayanta Dey🇮🇳 · Raghunath Sahoo🇮🇳 · Sabyasachi Ghosh🇮🇳
We have estimated the electrical and thermal conductivity of a hadron resonance gas for a time-varying magnetic field, which is also compared with constant and zero magnetic field cases. Considering the exponential decay of electromagnetic fields with time, a kinetic theory framework can provide the microscopic expression of electrical and thermal conductivity in terms of relaxation and decay times. In the absence of the magnetic field, only a single time scale appears, and in the finite magnetic field case, their expressions carry two-time scales, relaxation time and cyclotron time period. Estimating the conductivities for HRG matter in three cases -- zero, constant, and time-varying magnetic fields, we have studied the validity of the Wiedemann-Franz law. We noticed that at a high-temperature domain, the ratio saturates at a particular value, which may be considered as Lorenz number of the hadron resonance gas. With respect to the saturation values, the deviation of the Wiedemann-Franz law has been quantified at the low-temperature domain. For the first time, the present work sketches this quantitative deviation of the Wiedemann-Franz law for hadron resonance gas at a constant and a time-varying magnetic field.
↳ hep-phhep-exnucl-exnucl-thPRD(2023)·23 citations
08
New type of hydrogenlike charm-pion or charm-kaon matter
Si-Qiang Luo🇨🇳 · Zhan-Wei Liu🇨🇳 · Xiang Liu🇨🇳
Borrowing the structures of the hydrogen atom, molecular ion, and diatomic molecule, we predict the nature of a new type of hydrogenlike charm-pion or charm-kaon matter that could be obtained by replacing the proton and electron in hydrogen matter with a charmed meson and a pion or a kaon, respectively. We find that the spectra of the atom, molecular ion, and diatomic molecule can be obtained simultaneously with the Coulomb potential for the hydrogen, the charm-pion, and the charm-kaon systems. The predicted charm-pion matter also allows us to explore the mass shift mediated by the strong interaction. For the charm-pion and charm-kaon systems, the strong interactions could lead to binding energy shifts. Our calculations suggests that the binding energy shifts in charm-pion systems are in the order of several to tens of eV. For the charm-kaon systems, the results are in the order of tens to hundreds of eV. Exploring hydrogenlike charm-pion matter must lead to new demands for high-precision experiments.
↳ hep-phhep-exnucl-exnucl-thPRD(2023)·7 citations
09
Practicing carpe diem in the journey of studying physics: A brief review of the scientific contribution of Ru-Keng Su
Shaoyu Yin🇨🇳 · Wei-Liang Qian🇧🇷 · Ping Wang🇨🇳 · Bin Wang🇨🇳 · Rong-Gen Cai🇨🇳
We briefly review the scientific contributions of the late Prof. Ru-Keng Su in his academic life. In the area of intermediate and high-energy nuclear physics, Su explored various topics in high-energy nuclear physics and particle physics, inclusively about the finite temperature field theory, effective models for nuclear and quark matter, soliton, and quasiparticle models, among others. In gravity and cosmology, Su's research primarily embraces black hole thermodynamics, quasinormal modes, cosmological microwave background radiation, modified theories of gravity, and AdS/CFT correspondence and its applications. Besides, many aspects of Su's distinguished impact on the Chinese academic physics community are discussed. We also summarize the biographical and academic career of Su. This article is an elaborated version of the memorial article that will be published in \href{https://www.mdpi.com/journal/symmetry}{\it symmetry}.
↳ physics.hist-phhep-phnucl-th0 citations
10
Electric-field driven nonequilibrium phase transitions in AdS/CFT
Daisuke Endo🇯🇵 · Yuichi Fukazawa🇯🇵 · Masataka Matsumoto🇨🇳 · Shin Nakamura🇯🇵
We study phase transitions and critical phenomena in nonequilibrium steady states controlled by an electric field. We employ the D3/D7 model in the presence of a charge density and electric field at finite temperatures. The system undergoes the first-order and the second-order phase transitions under the variation of the electric field in the presence of dissipation. We numerically find that the critical exponents which we define for the nonequilibrium phase transition in this model take the mean-field values.
↳ hep-thcond-mat.stat-mechcond-mat.str-elnucl-thJHEP(2023)·4 citations
11
Interactions of $π K$ , $π π K$ and $K K π$ systems at maximal isospin from lattice QCD
Zachary T. Draper🇺🇸 · Andrew D. Hanlon🇺🇸 · Ben Hörz🇩🇪 · Colin Morningstar🇺🇸 · Fernando Romero-López🇺🇸 · Stephen R. Sharpe🇺🇸
We study the interactions of systems of two and three nondegenerate mesons composed of pions and kaons at maximal isospin using lattice QCD, specifically $π^{+} K^{+}$ , $π^{+} π^{+} K^{+}$ and $K^{+} K^{+} π^{+}$ . Utilizing the stochastic LapH method, we determine the spectrum of these systems on two CLS $N_{f} = 2 + 1$ ensembles with pion masses of $200$ MeV and $340$ MeV, and include many levels in different momentum frames. We constrain the K matrices describing two- and three-particle interactions by fitting the spectrum to the results predicted by the finite-volume formalism, including up to $p$ waves. This requires also results for the $π^{+} π^{+}$ and $K^{+} K^{+}$ spectrum, which have been obtained previously on the same configurations. We explore different fitting strategies, comparing fits to energy shifts with fits to energies boosted to the rest frame, and also comparing simultaneous global fits to all relevant two- and three-particle channels to those where we first fit two-particle channels and then add in the three-particle information. We provide the first determination of the three-particle K matrix in $π^{+} π^{+} K^{+}$ and $K^{+} K^{+} π^{+}$ systems, finding statistically significant nonzero results in most cases. We include $s$ and $p$ waves in the K matrix for $π^{+} K^{+}$ scattering, finding evidence for an attractive $p$ -wave scattering length. We compare our results to Chiral Perturbation Theory, including an investigation of the impact of discretization errors, for which we provide the leading order predictions obtained using Wilson Chiral Perturbation Theory.
↳ hep-lathep-phnucl-thJHEP(2023)·48 citations
12
Isolated photon production in $pp$ collisions at forward rapidities and high multiplicity events
Yuri N. Lima🇧🇷 · André V. Giannini🇧🇷 · Victor P. Goncalves🇧🇷
The production of isolated photons in high multiplicity events is investigated considering the Color Glass Condensate (CGC) formalism. The associated cross-section for proton - proton collisions is estimated considering three distinct solutions of the Balitsky - Kovchegov (BK) equation and predictions for the normalized photon yield as a function of the multiplicities of co - produced charged particles are presented. We predict the increasing of the yield with the multiplicity, with the slope being smaller for larger rapidities. As the isolated photon production is not affected by the fragmentation process, a future experimental investigation of this process in current high energy hadronic colliders is ideal to test the treatment of high multiplicity events using the CGC formalism, previously applied only for the production of hadronic final states.
↳ hep-phhep-exnucl-exnucl-thEPJA(2024)·7 citations
13
Proton Charge Radius from Lepton Scattering
Weizhi Xiong🇨🇳 · Chao Peng🇺🇸
Protons are bound states of the strong interaction governed by Quantum Chromodynamics (QCD). Its charge radius ( $r_{E}^{p}$ ) is an important quantity as it characterizes the spatial distribution of the proton's charge, which is carried by the quarks. On the other hand, the proton charge radius is an essential physical input for the bound-state Quantum Electrodynamic (QED) calculations for the hydrogen atomic energy levels. Nevertheless, the large discrepancy between $r_{E}^{p}$ measurements from muonic hydrogen spectroscopy, and those from $e p$ elastic scattering and ordinary hydrogen spectroscopy, have been puzzling physicists for over a decade. Tremendous efforts, in both theoretical and experimental sides, have been dedicated to providing various insights into this puzzle, yet certain issues still remain unresolved, particularly in the field of lepton scatterings. This review will focus on $r_{E}^{p}$ measurements using lepton scatterings, the recent theoretical and experimental developments in this field, as well as future experiments using this technique.
↳ nucl-exhep-exhep-phnucl-thUniverse(2023)·26 citations
14
Experimental evidence of the effect of nuclear shells on fission dissipation and time
D. Ramos🇪🇸 · M. Caamano🇪🇸 · F. Farget🇫🇷 · C. Rodriguez-Tajes🇫🇷 · A. Lemasson🇫🇷 · C. Schmitt🇫🇷 · L. Audouin🇫🇷 · J. Benlliure🇪🇸 · E. Casarejos🇪🇸 · E. Clement🇫🇷 · D. Cortina🇪🇸 · O. Delaune🇫🇷 and 11 other authors
Nuclear fission is still one of the most complex physical processes we can observe in nature due to the interplay of macroscopic and microscopic nuclear properties that decide the result. An example of this coupling is the presence of nuclear dissipation as an important ingredient that contributes to drive the dynamics and has a clear impact on the time of the process. However, different theoretical interpretations, and scarce experimental data make it poorly understood. In this letter, we present the first experimental determination of the dissipation energy in fission as a function of the fragment split, for three different fissioning systems. The amount of dissipation was obtained through the measurement of the relative production of fragments with even and odd atomic numbers with respect to different initial fission energies. The results reveal a clear effect of particular nuclear shells on the dissipation and fission dynamics. In addition, the relative production of fragments with even and odd atomic numbers appears as a potential contributor to the long-standing problem of the time scale in fission.
↳ nucl-exnucl-thPRC(2023)·9 citations
15
The Spectrum of Low- $p_{T}$ $J / ψ$ in Heavy-Ion Collisions in a Statistical Two-Body Fractal Model
Huiqiang Ding🇨🇳 · Luan Cheng🇨🇳 · Tingting Dai🇨🇳 · Enke Wang🇨🇳 · Wei-Ning Zhang🇨🇳
We establish a statistical two-body fractal (STF) model to study the spectrum of $J / ψ$ . $J / ψ$ serves as a reliable probe in heavy-ion collisions. The distribution of $J / ψ$ in hadron gas is influenced by flow, quantum and strong interaction effects. Previous models have predominantly focused on one or two of these effects while neglecting the others, resulting in the inclusion of unconsidered effects in the fitted parameters. Here, we study the issue from a new point of view by analyzing the fact that all three effects induce a self-similarity structure, involving a $J / ψ$ - $π$ two-meson state and a $J / ψ$ , $π$ two-quark state, respectively. We introduce modification factor $q_{T B S}$ and $q_{2}$ into the probability and entropy of charmonium. $q_{T B S}$ denotes the modification of self-similarity on $J / ψ$ , $q_{2}$ denotes that of self-similarity and strong interaction between \emph{c }and $c ˉ$ on quarks. By solving the probability and entropy equations, we derive the values of $q_{T B S}$ and $q_{2}$ at various collision energies and centralities. Substituting the value of $q_{T B S}$ into distribution function, we successfully obtain the transverse momentum spectrum of low- $p_{T}$ $J / ψ$ , which demonstrates good agreement with experimental data. The STF model can be employed to investigate other mesons and resonance states.
↳ hep-phnucl-thEntropy(2023)·2 citations
16
Charmonium production in a thermalizing heat bath
Taesoo Song🇩🇪 · Joerg Aichelin🇫🇷 · Elena Bratkovskaya🇩🇪
Using the Remler formalism for the creation of composed particles, we study charmonium production both in thermalized and thermalizing boxes, which contain charm and anticharm quarks. The thermalizing box studies include the lowering of the box temperature, the spatial diffusion of charm and anticharm quarks, which are initially confined in the central region, as well as the combination of both, what imitates heavy-ion collisions. Comparing numerical and analytical results we demonstrate that the rate of the original Remler formalism has to be supplemented by two rates to obtain, for $t \to \infty$ , results, which are consistent with the statistical model predictions: i) a rate, which takes into account the temperature dependence of the Wigner density of the quarkonium during the expansion and, in the case that a heavy quark potential is not implemented in the Monte Carlo approach, ii) a rate which comes from the change of the relative distance between the heavy quark and antiquark. These results provide the basis for future applications of the Remler formalism to heavy-ion collisions.
↳ hep-phnucl-thPRC(2023)·10 citations

Affiliations

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