Nuclear Theory·nucl-th

Thursday·July 16, 2020

12 papers—6 primary·6 cross-listed

01
Effective Field Theory for Two-Body Systems with Shallow S-Wave Resonances
J. Balal Habashi🇺🇸 · S. Sen🇺🇸 · S. Fleming🇺🇸 · U. van Kolck🇫🇷
Resonances are of particular importance to the scattering of composite particles in quantum mechanics. We build an effective field theory for two-body scattering which includes a low-energy $S$ -wave resonance. Our starting point is the most general Lagrangian with short-range interactions. We demonstrate that these interactions can be organized into various orders so as to generate a systematic expansion for an $S$ matrix with two low-energy poles. The pole positions are restricted by renormalization at leading order, where the common feature is a non-positive effective range. We carry out the expansion explicitly to next-to-leading order and illustrate how it systematically accounts for the results of a toy model -- a spherical well with a delta shell at its border.
nucl-thAnnals Phys.(2020)·19 citations
02
Properties of nuclear pastas
Jorge A. Lopez · Claudio O. Dorso · Guillermo A. Frank
In this Review we study the nuclear pastas as they are expected to be formed in neutron star cores. We start with a study of the pastas formed in nuclear matter (composed of protons and neutrons), we follow with the role of the electron gas on the formation of pastas, and we then investigate the pastas in neutron star matter (nuclear matter embedded in an electron gas).
nucl-thFront.Phys.(Beijing)(2021)·25 citations
03
Nuclear shape evolution and shape coexistence in Zr and Mo isotopes
Pankaj Kumar · Virender Thakur · Smriti Thakur · Vikesh Kumar · Shashi K. Dhiman
The phenomena of shape evolution and shape coexistence in even-even $^{88 - 126}$ Zr and $^{88 - 126}$ Mo isotopes is studied by employing covariant density functional theory (CDFT) with density-dependent point coupling parameter sets DD-PCX and DD-PC1, and with separable pairing interaction. The results for rms deviation in binding energies, two-neutron separation energy, the differential variation of two-neutron separation energy, and rms charge radii, as a function of neutron number, are presented and compared with available experimental data. In addition to the oblate-prolate shape coexistence in $^{96 - 110}$ Zr isotopes, the correlation between shape transition and discontinuity in the observables are also examined. A smooth trend of charge radii in Mo isotopes is found to be due to the manifestation of triaxiality softness. The observed oblate and prolate minima are related to the low single-particle energy level density around the Fermi level of neutron and proton respectively. The present calculations also predict a deformed bubble structure in $^{100}$ Zr isotope.
nucl-thEPJA(2021)·16 citations
04
Bayesian inference of nuclear symmetry energy from measured and imagined neutron skin thickness in $^{116, 118, 120, 122, 124, 130, 132}$ Sn, $^{208}$ Pb, and $^{48}$ Ca
Jun Xu · Wen-Jie Xie · Bao-An Li
The neutron skin thickness $Δ r_{n p}$ in heavy nuclei has been known as one of the most sensitive terrestrial probes of the nuclear symmetry energy around $\frac{2}{3}$ of the saturation density $ρ_{0}$ of nuclear matter. Existing neutron skin data mostly from hadronic observables suffer from large uncertainties and their extraction from experiments are often strongly model dependent. While waiting eagerly for the promised model-independent and high-precision neutron skin data for $^{208}$ Pb and $^{48}$ Ca from the parity-violating electron scattering experiments (PREX-II and CREX at JLab as well as MREX at MESA), within the Bayesian statistical framework using the Skyrme-Hartree-Fock model we infer the posterior probability distribution functions (PDFs) of the slope parameter $L$ of the nuclear symmetry energy at $ρ_{0}$ from imagined $Δ r_{n p} (^{208}$ Pb $) = 0.15$ , 0.20, and 0.30 fm as well as $Δ r_{n p} (^{48}$ Ca $) = 0.12$ , 0.15, and 0.25 fm, with different $1 σ$ error bars. The results are compared with the PDFs of $L$ inferred using the same approach from the available $Δ r_{n p}$ data for Sn isotopes from hadronic probes. They are also compared with results from a recent Bayesian analysis of the radius and tidal deformability data of canonical neutron stars from GW170817 and NICER. The neutron skin data for Sn isotopes gives $L = 45. 5_{- 21.6}^{+ 26.5}$ MeV surrounding its mean value or $L = 53. 4_{- 29.5}^{+ 18.6}$ MeV surrounding its maximum {\it a posteriori} value, respectively, with the latter smaller than but consistent with the $L = 6 6_{- 20}^{+ 12}$ MeV from the neutron star data within their 68\% confidence intervals. In order to provide additionally useful information on $L$ extracted from the $Δ r_{n p}$ of Sn isotopes, the experimental error bar of $Δ r_{n p} (^{208}$ Pb) should be at least smaller than 0.06 fm aimed by some current experiments.
nucl-thnucl-exPRC(2020)·55 citations
05
Formation of light nuclei at chemical freezeout: Description within a statistical thermal model
Deeptak Biswas🇮🇳
The thermal description of light nuclei at the chemical freeze-out has been investigated. First, I have verified the equilibration of the light nuclei and then introduced a new method to investigate the light nuclei formation. One can study the proximity between the phase space density of light nuclei ratios and their hadronic constituents e.g $d ˉ / d$ and $(p ˉ n ˉ / p n)$ . I have found that with the exclusion of the decay feed-down from the hadronic yields in the thermal model, the hadronic representations have good agreement with the light nuclei ratios. I have performed a similar analysis with the ratio of $Λ$ -hypernuclei and $^{3} H e$ , which is related to the ratio $Λ/ p$ . In this context, the strangeness population factor $S_{3}$ has been studied also. These results indicate that the nuclei and hypernuclei formation may occur near the standard chemical freeze-out and before the decay of the hadronic resonances. This method will serve as a guideline to discuss the light nuclei formation and the inclusion of decay into their hadronic constituents.
nucl-thhep-phPRC(2020)·10 citations
06
Extracting the temperature dependence in high- $p_{⊥}$ particle energy loss
Stefan Stojku🇷🇸 · Bojana Ilic🇷🇸 · Marko Djordjevic🇷🇸 · Magdalena Djordjevic🇷🇸
The suppression of high- $p_{⊥}$ particles is one of the main signatures of parton energy loss during its passing through the QGP medium, and is reasonably reproduced by different theoretical models. However, a decisive test of the reliability of a certain energy loss mechanism, apart from its path-length, is its temperature dependence. Despite its importance and comprehensive dedicated studies, this issue is still awaiting for more stringent constraints. To this end, we here propose a novel observable to extract temperature dependence exponent of high- $p_{⊥}$ particle's energy loss, based on $R_{AA}$ . More importantly, by combining analytical arguments, full-fledged numerical calculations and comparison with experimental data, we argue that this observable is highly suited for testing (and rejecting) the long-standing $Δ E / E \propto L^{2} T^{3}$ paradigm. The anticipated significant reduction of experimental errors will allow direct extraction of temperature dependence, by considering different centrality pair in $A + A$ collisions (irrespective of the nucleus size) in high- $p_{⊥}$ region. Overall, our results imply that this observable, which reflects the underlying energy loss mechanism, is very important to distinguish between different theoretical models.
nucl-thhep-phPRC(2021)·15 citations
07
Jet-based measurements of Sivers and Collins asymmetries at the future Electron-Ion Collider
Miguel Arratia🇺🇸 · Zhong-Bo Kang🇺🇸 · Alexei Prokudin🇺🇸 · Felix Ringer🇺🇸
We present predictions and projections for hadron-in-jet measurements and electron-jet azimuthal correlations at the future Electron-Ion Collider (EIC). These observables directly probe the three-dimensional (3D) structure of hadrons, in particular, the quark transversity and Sivers parton distributions and the Collins fragmentation functions. We explore the feasibility of these experimental measurements by detector simulations and discuss detector requirements. We conclude that jet observables have the potential to enhance the 3D imaging EIC program.
↳ hep-phhep-exnucl-exnucl-thPRD(2020)·63 citations
08
Resolution of hyper-triton chemical freeze-out puzzle in high energy nuclear collisions
O. V. Vitiuk🇺🇦 · K. A. Bugaev🇺🇦 · E. S. Zherebtsova🇷🇺 · D. B. Blaschke🇷🇺 · L. V. Bravina🇳🇴 · E. E. Zabrodin🇳🇴 · G. M. Zinovjev🇺🇦
The recently developed hadron resonance gas model with multicomponent hard-core repulsion is used to address and resolve the long standing problem to describe the light nuclear cluster multiplicities including the hyper-triton measured by the STAR Collaboration, known as the hyper-triton chemical freeze-out puzzle. An unprecedentedly accurate description is obtained for the hadronic and other light nuclear cluster data measured by STAR at the collision energy $s_{N N} = 200$ GeV and by ALICE at $s_{N N} = 2.76$ TeV. This success is achieved by applying the new strategy of analyzing the light nuclear cluster data and by using the value for the hard-core radius of the (anti-) $Λ$ hyperons found in earlier work. One of the most striking results of the present work is that for the most probable scenario of chemical freeze-out for the STAR energy the obtained parameters allow to simultaneously reproduce the values of the experimental ratios $S_{3}$ and $S ˉ_{3}$ which were not included in the fit.
↳ hep-phnucl-thEPJA(2021)·9 citations
09
Nonperturbative quark matter equations of state with vector interactions
Konstantin Otto🇩🇪 · Micaela Oertel🇫🇷 · Bernd-Jochen Schaefer🇩🇪
Nonperturbative equations of state (EoSs) for two and three quark flavors are constructed with the functional renormalization group (FRG) within a quark-meson model truncation augmented by vector mesons for low temperature and high density. Based on previous FRG studies without repulsive vector meson interactions the influence of isoscalar vector $ω$ - and $ϕ$ -mesons on the dynamical fluctuations of quarks and (pseudo)scalar mesons is investigated. The grand potential as well as vector meson condensates are evaluated as a function of quark chemical potential and the quark matter EoS in $β$ -equilibrium is applied to neutron star (NS) physics. The tidal deformability and mass-radius relations for hybrid stars from combined hadronic and quark matter EoSs are compared for different vector couplings. We observe a significant impact of the vector mesons on the quark matter EoS such that the resulting EoS is sufficiently stiff to support two-solar-mass neutron stars.
↳ hep-phastro-ph.HEnucl-thEur.Phys.J.ST(2020)·54 citations
10
Inclusive Hadroproduction of $P$ -Wave Heavy Quarkonia in Potential Nonrelativistic QCD
Nora Brambilla🇩🇪 · Hee Sok Chung🇩🇪 · Antonio Vairo🇩🇪
We compute the color-singlet and color-octet nonrelativistic QCD (NRQCD) long-distance matrix elements for inclusive production of $P$ -wave quarkonia in the framework of potential NRQCD. In this way, the color-octet NRQCD long-distance matrix element can be determined without relying on measured cross section data, which has not been possible so far. We obtain inclusive cross sections of $χ_{c J}$ and $χ_{b J}$ at the LHC, which are in good agreement with data. In principle, the formalism developed in this Letter can be applied to all inclusive production processes of heavy quarkonia.
↳ hep-phhep-exhep-latnucl-thPRL(2021)·30 citations
11
A study of charm quark dynamics in quark-gluon plasma with 3+1 D viscous hydrodynamics
Manu Kurian🇮🇳 · Mayank Singh🇨🇦 · Vinod Chandra🇮🇳 · Sangyong Jeon🇨🇦 · Charles Gale🇨🇦
The drag and diffusion coefficients are studied within the framework of Fokker-Planck dynamics for the case of a charm quark propagating in an expanding quark-gluon plasma. The space-time evolution of the nuclear matter created in the relativistic heavy-ion collision is modelled using MUSIC, a 3+1 D relativistic viscous hydrodynamic approach. The effect of viscous corrections to the heavy quark transport coefficients is explored by considering scattering processes with thermal quarks and gluons in the medium. It is observed that the momentum diffusion of the heavy quarks is sensitive to the shear and bulk viscosity to entropy ratios. The collisional energy loss of the charm quark in the viscous quark-gluon plasma is analyzed.
↳ hep-phnucl-exnucl-thPRC(2020)·31 citations
12
Doubly Heavy Baryon Xi_cc Production in Upsilon (1S) Decay
Shi-Yuan Li🇨🇳 · Zhen-Yang Li🇨🇳 · Zong-Guo Si🇨🇳 · Zhong-Juan Yang🇨🇳 · Xiao Zhang🇨🇳
Upsilon (1S) decay to Xi_cc +anything is studied. It is shown that the branching ratio can be as significant as that of Upsilon (1S) decay to J/Psi +anything. The non-relativistic heavy quark effective theory framework is employed for the calculation on the decay width. Measurements on the production of Xi_cc and likely production characteristic of the partonic state with four charm quarks at BELLE2 are suggested.
↳ hep-phnucl-thPRD(2021)·10 citations

Affiliations

first authorsco-authorsvia INSPIRE