Nuclear Theory·nucl-th

Friday·June 24, 2022

8 papers—5 primary·3 cross-listed

01
Complete experiment problem for photoproduction of two pseudoscalar mesons on a nucleon in a truncated partial-wave analysis
A. Fix🇷🇺 · I. Dementjev🇷🇺
It is shown that within a truncated partial wave analysis for photoproduction of two pseudoscalar mesons, it is possible to halve the number of independent partial amplitudes by taking into account parity conservation. In addition, within the framework of the proposed formalism, one can rather easily resolve the double discrete ambiguity arising from the symmetry under complex conjugation of the helicity amplitudes. This leads to essential simplifications of the complete experiment problem, at least as far as mathematical aspects are concerned.
nucl-thhep-phPRC(2022)·1 citation
02
Charmonium dissociation at high baryon chemical potential
Bo Tong🇨🇳 · Baoyi Chen🇨🇳
We study the charmonium dissociation in the hot medium with finite baryon chemical potential $μ_{B}$ . Charmonium bound states are dissociated in the medium by the color screening effect and the random scatterings with thermal partons, which are included in the real and imaginary parts of the potential respectively. $J / ψ$ fraction in the $c c ˉ$ pair defined to be the quantum overlap between the wave package and the wave function of $J / ψ$ eigenstate decreases with time due to the complex potentials. When $μ_{B}$ is large compared with the medium temperature, the Deybe mass is increased evidently. We consider $μ_{B}$ -dependent Deybe mass in both real and imaginary parts of the potential to calculate the $J / ψ$ survival probability in the static medium and the Bjorken medium. $J / ψ$ survival probability is reduced evidently by the $μ_{B}$ effect at low temperatures available in the medium produced in Beam Energy Scan experiments, while this effect becomes not apparent at high temperatures.
nucl-thhep-phPRC(2022)·2 citations
03
Formation of large chunk of nuclear matter in heavy-ion collisions
Gao-Chan Yong🇨🇳
In terrestrial laboratory with existing accelerators, the maximum multinucleon system produced so far is limited to that with total nucleon number being less than the sum of two colliding nuclei. Such situation may hinder our studies on the properties of nuclear many-body system. Here a way of producing large multinucleon system via multi-nucleus collision device Collider Plus in terrestrial laboratory is proposed. It is shown that large chunk of nucleonic matter can be produced through nuclear ternary fusion reactions at lower beam energies and also large block of dense matter can be formed via ternary collisions of heavy nuclei at intermediate energies. These investigations may shed lights on the studies of the synthesis of superheavy elements and the properties of bulk superdense nuclear matter.
nucl-thnucl-exPLB(2022)·0 citations
04
Mass radius and mechanical properties of the proton via strange $ϕ$ meson photoproduction
Xiao-Yun Wang🇨🇳 · Chen Dong🇨🇳 · Quanjin Wang🇨🇳
In this work, the cross sections of $ϕ$ photoproduction are systematically investigated with the two gluon exchange model and the pomeron model. The results obtained show that the theoretical values of the two models agree well with the experimental data. Since the mass radius and mechanical properties of the proton are encoded in the scalar gravitational form factor of the momentum energy tensor, based on the differential cross sections of $ϕ$ photoproduction at near-threshold predicted by the two gluon exchange model, the average mass radius of the proton is derived as $⟨ r^{2} ⟩_{m} = 0.78 \pm 0.06$ fm. As a comparison, we directly extract the proton mass radius from the experimental data of $ϕ$ photoproduction to obtain an average value of $0.80 \pm 0.05$ fm, which is very close to the result given by the two gluon exchange model. Taking a similar approach, we extracted the average value of $m_{D}$ to obtain the distribution of the pressure and shear force contributed within the proton, and compared the results with other groups. The results of this paper may provide necessary theoretical information for the subsequent in-depth study of the internal structure and properties of proton.
nucl-thPRD(2022)·20 citations
05
Tensor polarization and the dissipative damping of vector meson in QCD Medium
Feng Li🇨🇳 · Shuai Y. F. Liu🇨🇳
Unexpectedly large and puzzling spin alignment, and thus tensor polarization, of vector mesons has been observed in heavy-ion collisions. Given that tensor polarization represents a fluctuation of spin, we derive, for the first time, a fluctuation-dissipation relation for tensor polarization, where the polarization is proportional to first-order hydrodynamic gradients (e.g., the shear-stress tensor), with dissipative coefficients depending on the particle's damping properties, as characterized by its spectral function. Employing relativistic hydrodynamics at finite density, we find that dissipative contributions can generate substantial spin alignment. We provide illustrative examples (by tuning one coefficients $α_{sh}$ ) that generate a beam energy, $p_{T}$ , and centrality dependence of spin alignment resembling those observed in experiments, offering insights into these puzzling phenomena and demonstrating its potential as a ``spectrometer" for in-medium vector mesons.
nucl-thhep-ph45 citations
06
Equation of state for hot hyperonic neutron star matter
Hristijan Kochankovski🇪🇸 · Angels Ramos🇪🇸 · Laura Tolos🇪🇸
The FSU2H equation-of-state model, originally developed to describe cold neutron star matter with hyperonic cores, is extended to finite temperature. Results are presented for a wide range of temperatures and lepton fractions, which cover the conditions met in protoneutron star matter, neutron star mergers and supernova explosions. It is found that the temperature effects on the thermodynamical observables and the composition of the neutron star core are stronger when the hyperonic degrees of freedom are considered. An evaluation of the temperature and density dependence of the thermal index leads to the observation that the so-called $Γ$ law, widely used in neutron star merger simulations, is not appropriate to reproduce the true thermal effects, specially when hyperons start to be abundant in the neutron star core. To make finite temperature equations of state easily accessible, simple parameterizations of the thermal index for nucleonic and hyperonic $β$ -stable neutrino-free matter are provided.
↳ astro-ph.HEnucl-thMNRAS(2022)·41 citations
07
Sensitivity of Neutron Star Observations to Three-nucleon Forces
Andrea Sabatucci🇮🇹 · Omar Benhar🇮🇹 · Andrea Maselli🇮🇹 · Costantino Pacilio🇮🇹
Astrophysical observations of neutron stars have been widely used to infer the properties of the nuclear matter equation of state. Beside being a source of information on average properties of dense matter, however, the data provided by electromagnetic and gravitational wave (GW) facilities are reaching the accuracy needed to constrain, for the first time, nuclear dynamics in dense matter. In this work we assess the sensitivity of current and future neutron star observations to directly infer the strength of repulsive three-nucleon forces, which are key to determine the stiffness of the equation of state. Using a Bayesian approach we focus on the constraints that can be derived on three-body interactions from binary neutron star mergers observed by second and third-generation of gravitational wave interferometers. We consider both single and multiple observations. For current detectors at design sensitivity the analysis suggests that only low mass systems, with large signal-to-noise ratios (SNR), allow to reliably constrain the three-body forces. However, our results show that a single observation with a third-generation interferometer, such as the Einstein Telescope or Cosmic Explorer, will constrain the strength of the repulsive three-body potential with exquisite accuracy, turning third-generation GW detectors into new laboratories to study the nucleon dynamics.
↳ astro-ph.HEgr-qcnucl-thPRD(2022)·19 citations
08
Shear-induced anomalous transport and charge asymmetry of triangular flow in heavy-ion collisions
Matteo Buzzegoli🇺🇸 · Dmitri E. Kharzeev🇺🇸 · Yu-Chen Liu🇺🇸 · Shuzhe Shi🇺🇸 · Sergei A. Voloshin🇺🇸 · Ho-Ung Yee🇺🇸
Chiral anomaly implies the existence of non-dissipative transport phenomena, such as the chiral magnetic effect. At second order in the derivative expansion, novel quantum transport phenomena emerge. In this paper, we focus on the anomalous transport driven by a combination of shear, vorticity and magnetic field. We find that the corresponding transport phenomena -- shear-induced chiral magnetic and chiral vortical effects (siCME and siCVE) -- induce characteristic charge correlations among the hadrons produced in heavy ion collisions. We propose the charge asymmetry of triangular flow as a signature of the anomalous transport, and estimate the strength of the signal, as well as the background, using hydrodynamical model simulations. We find that the signal-to-background ratio for the proposed observable is favorable for experimental detection.
↳ hep-phnucl-exnucl-thPRC(2022)·9 citations

Affiliations

first authorsco-authorsvia INSPIRE