Nuclear Theory·nucl-th

Tuesday·December 21, 2021

10 papers—3 primary·7 cross-listed

01
Specific heat and its high-order moments in relativistic heavy-ion collisions from a multiphase transport model
Ru-Xin Cao🇨🇳 · Song Zhang🇨🇳 · Yu-Gang Ma🇨🇳
Energy dependence of specific heat extracted from temperature fluctuation of Au + Au collisions at $s_{N N}$ = 7.7 GeV to 200 GeV was investigated by using a multiphase transport (AMPT) model. The results were compared with those from other models and some differences at low $s_{N N}$ were found. To explain the above differences and describe the properties of the hot dense matter at low $s_{N N}$ , a new quantity $C_{v}^{*}$ was derived for describing specific heat in heavy-ion collisions. It was found that, by using $C_{v}^{*}$ together with its high order moments (skewness and kurtosis), thermal properties of the hot dense matter can be described and different thermal properties with or without parton process can be clearly distinguished. The proposed observable provides a way to learn the property of QCD matter % phase transition %along with critical point in heavy-ion collisions.
nucl-thhep-phnucl-exPRC(2022)·13 citations
02
Short range correlations in the extended quantum molecular dynamics model
Lei Shen · Bo-Son Huang · Yu-Gang Ma
Short-range potential has been added into an extended quantum molecular dynamics (EQMD) model. The RMS radius, binding energy and momentum distribution of $^{12}$ C with different initial structures and short-range potential parameters have been checked. The separation energy of $^{12}$ C(p,2p) $^{11}$ B reaction is calculated and compared with the experimental data, it indicates that our modified EQMD model can be taken as a reliable tool for studying proton pair knock-out reaction. Furthermore, the short range correlation effects on emission time and momentum spectrum of two protons are discussed. Finally, the momentum correlation function of the emitted proton pair is calculated by the Lednicky and Lyuboshitz's analytical method. The result explains that short-range repulsion causes high momentum tail and weakens the momentum correlation function.
nucl-thnucl-exPRC(2022)·17 citations
03
Linking partial dynamical symmetry to nuclear energy density functionals
A. Leviatan · N. Gavrielov · K. Nomura
We use self-consistent mean-field methods in combination with the interacting boson model (IBM) of nuclei, to establish a linkage between universal energy density functionals (EDFs) and partial dynamical symmetry (PDS). An application to $^{168}$ Er shows that IBM Hamiltonians derived microscopically from known nonrelativistic and relativistic EDFs in this region, conform with SU(3)-PDS.
nucl-thBulg.J.Phys.(2022)·2 citations
04
Incorporating the weak mixing angle dependence to reconcile the neutron skin measurement on 208Pb by PREX-II
Mattia Atzori Corona🇮🇹 · Matteo Cadeddu🇮🇹 · Nicola Cargioli🇮🇹 · Paolo Finelli🇮🇹 · Matteo Vorabbi🇺🇸
The only available electroweak measurement of the $^{208} Pb$ neutron skin, $Δ R_{np}$ , performed by the PREX-II Collaboration through polarized electron-lead scattering, shows a mild tension with respect to both the theoretical nuclear-model predictions and a host of measurements. However, the dependence on the weak mixing angle should be incorporated in the calculation, since its low-energy value is experimentally poorly known. We first repeat the PREX-II analysis confirming their measurement by fixing the weak mixing angle to its standard model value. Then, we show the explicit dependence of the PREX-II measurement on the weak mixing angle, obtaining that it is fully degenerate with the neutron skin. To break this degeneracy, we exploit the weak mixing angle measurement from atomic parity violation on lead, obtaining a slightly thinner neutron skin but with about doubled uncertainties, possibly easing the PREX tension. Relying on the theoretical prediction, $Δ R_{np}^{th} \approx 0.13 - 0.19 fm$ , and using it as a prior in the fit, we find a weak mixing angle value about $1.2 σ$ smaller than the standard model prediction. Thus, we suggest a possible solution of the PREX-II tension by showing that, considering its underlying dependence on the weak mixing angle, the PREX-II neutron skin determination could be in agreement with the other available measurements and predictions if the weak mixing angle at the proper energy scale is smaller than the standard model prediction.
↳ hep-phnucl-exnucl-thPRC(2022)·20 citations
05
When cold, dense quarks in 1+1 and 3+1 dimensions are not a Fermi liquid
Marton Lajer🇺🇸 · Robert M. Konik🇺🇸 · Robert D. Pisarski🇺🇸 · Alexei M. Tsvelik🇺🇸
We analyze the behavior of quarks coupled to a $S U (N_{c})$ gauge theory in 1+1 dimensions. In the limit of strong coupling, the model reduces to a Wess-Zumino-Novikov-Witten (WZNW) model. At nonzero density, excitations near the Fermi surface form a non-Fermi liquid. With $N_{f}$ flavors, the finite density of quarks reduce to a free $U (1)$ field, which governs fluctuations in baryon number, together with a WZNW $S U (N_{f})$ nonlinear sigma model at level $N_{c}$ , from the pion/kaon modes. We compute the singularity in the charge susceptibility at the Fermi surface and the attendant power law correlations. We suggest that this is relevant to the quarkyonic regime of cold, dense QCD in 3+1 dimensions, in the limit that the Fermi surface is covered by many small patches, and the theory is effectively one dimensional. In this regime the dominant excitations near the Fermi surface are not baryons, but gapless bosonic modes.
↳ hep-thcond-mat.str-elhep-phnucl-thPRD(2022)·9 citations
06
Universal relations for rapidly rotating cold and hot hybrid star
Noshad Khosravi Largani · Tobias Fischer · Armen Sedrakian · Mateusz Cierniak · David E. Alvarez-Castillo · David B. Blaschke
Several global parameters of compact stars are related via empirical relations, which are (nearly) independent of the underlying equation of state (EoS) of dense matter and, therefore, are said to be universal. We investigate the universality of relations that express the maximum mass and the radius of non-rotating and maximally rapidly rotating configurations, as well as their moment of inertia, in terms of the compactness of the star. For this, we first utilize a collection of cold (zero-temperature) and hot (isentropic) nucleonic EoS and confirm that the universal relations are holding for our collection of EoS. We then go on, to add to our collection and test for the same universality models of EoS that admit a strong first-order phase transition from nucleonic to deconfined quark matter. Also in this case we find that the universal relations hold, in particular for hot, isentropic hybrid stars. By fitting the universal relations to our computed data, we determine the coefficients entering these relations and the accuracy to which they hold.
↳ astro-ph.HEnucl-thMNRAS(2022)·38 citations
07
Measurement of the {\alpha}-particle monopole transition form factor challenges theory: a low-energy puzzle for nuclear forces?
S. Kegel · P. Achenbach · S. Bacca · N. Barnea · J. Bericic · D. Bosnar · L. Correa · M. O. Distler · A. Esser · H. Fonvieille · I. Friscic · M. Heilig and 21 other authors
We perform a systematic study of the $α$ -particle excitation from its ground state $0_{1}^{+}$ to the $0_{2}^{+}$ resonance. The so-called monopole transition form factor is investigated via an electron scattering experiment in a broad $Q^{2}$ -range (from $0.5$ to $5.0$ fm $^{- 2}$ ). The precision of the new data dramatically superseeds that of older sets of data, each covering only a portion of the $Q^{2}$ -range. The new data allow the determination of two coefficients in a low-momentum expansion leading to a new puzzle. By confronting experiment to state-of-the-art theoretical calculations we observe that modern nuclear forces, including those derived within chiral effective field theory which are well tested on a variety of observables, fail to reproduce the excitation of the $α$ -particle.
↳ nucl-exnucl-thPRL(2023)·28 citations
08
Predictions for neutron stars from holographic nuclear matter
Nicolas Kovensky🇫🇷 · Aaron Poole🇬🇧 · Andreas Schmitt🇬🇧
We discuss masses, radii, and tidal deformabilities of neutron stars constructed from the holographic Witten-Sakai-Sugimoto model. Using the same model for crust and core of the star, we combine our theoretical results with the latest astrophysical data, thus deriving more stringent constraints than given by the data alone. For instance, our calculation predicts -- independent of the model parameters -- an upper limit for the maximal mass of the star of about 2.46 solar masses and a lower limit of the (dimensionless) tidal deformability of a 1.4-solar-mass star of about 277.
↳ astro-ph.HEhep-phhep-thnucl-thSciPost Phys.Proc.(2022)·11 citations
09
Study of the hidden charm $D D ˉ^{*}$ interactions in chiral effective field theory
Hao Xu🇨🇳
We study the chiral interactions of the hidden charm $D D ˉ^{*}$ system within chiral effective field theory. Chiral Lagrangians are constructed by incorporating the chiral symmetry, heavy quark symmetry as well as proper charge conjugation properties of the heavy mesons. The interacting potentials of the $S$ -wave $D D ˉ^{*}$ are calculated up to second chiral order at 1-loop level, where complete two-pion exchange interactions are included. We further investigate the behaviors of the potentials in coordinate space, as well as their bound state properties. Our studies indicate that there exists a interacting strength ordering among considered four channels: $str. [0^{+} (1^{++})] > str. [0^{-} (1^{+-})] > str. [1^{+} (1^{+-})] > str. [1^{-} (1^{++})]$ where str. stands for the strength of the $D D ˉ^{*}$ interaction. Moreover, we find that $X (3872)$ can be treated as a good candidate of $0^{+} (1^{++})$ molecular state. There also tends to form $0^{-} (1^{+-})$ and $1^{+} (1^{+-})$ molecular states and we expect the experiments to search for the predicted multi-structures around the $D D ˉ^{*}$ mass region.
↳ hep-phhep-latnucl-thPRD(2022)·8 citations
10
Study of the Isomeric State in $^{16}$ N Using the $^{16}$ N $^{g, m}$ ( $d$ , $^{3}$ He) Reaction
T. L. Tang · C. R. Hoffman · B. P. Kay · I. A. Tolstukhin · S. Almaraz-Calderon · B. W. Asher · M. L. Avila · Y. Ayyad · K. W. Brown · D. Bazin · J. Chen · K. A. Chipps and 10 other authors
The isomeric state of $^{16}$ N was studied using the $^{16}$ N $^{g, m}$ ( $d$ , $^{3}$ He)~proton-removal reactions at \mbox{11.8~MeV/ $u$ } in inverse kinematics. The $^{16}$ N beam, of which 24% was in the isomeric state, was produced using the ATLAS in-fight facility and delivered to the HELIOS spectrometer, which was used to analyze the $^{3}$ He ions from the ( $d$ , $^{3}$ He) reactions. The simultaneous measurement of reactions on both the ground and isomeric states, reduced the systematic uncertainties from the experiment and in the analysis. A direct and reliable comparison of the relative spectroscopic factors was made based on a Distorted-Wave Born Approximation approach. The experimental results suggest that the isomeric state of $^{16}$ N is an excited neutron-halo state. The results can be understood through calculations using a Woods-Saxon potential model, which captures the effects of weak-binding.
↳ nucl-exnucl-thPRC(2022)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE