Nuclear Theory·nucl-th

Friday·June 26, 2020

16 papers—6 primary·10 cross-listed

01
Estrellas híbridas con núcleos superconductores de color
Daniela Curin · Ignacio F. Ranea-Sandoval · Milva G. Orsaria · Gustavo A. Contrera
The aim of this work is the study of hybrid stars interiors from the equations of state describing the matter composing them. We used modern hadronic equations of state to describe the matter in the outer core of these stars. The quark phase is modeled by an extended version of the Field Correlator Method, in which vector interactions among quarks and color superconductivity are included. We analyze the effect of these two contributions on the mass-radius relationship and tidal deformability. This is a relevant quantity for neutron stars after the GW170817 event, allowing to impose additional constraints to the equation of state of these compact objetcs.
nucl-thastro-ph.HEastro-ph.IM0 citations
02
What's in the core of massive neutron stars?
Yong-Liang Ma🇨🇳 · Mannque Rho🇫🇷
When hadron-quark continuity is formulated in terms of a topology change at a density higher than twice the nuclear matter densiy $n_{0}$ the core of massive compact stars can be described in terms of quasiparticles of fractional baryon charges, behaving neither like pure baryons nor deconfined quarks. Hidden symmetries, both local gauge and pseudo-conformal (or broken scale), emerge and give rise to the long-standing quenched $g_{A}$ in nuclear Gamow-Teller transitions at $\sim n_{0}$ and to the pseudo-conformal sound velocity $v_{p cs}^{2} / c^{2} \approx 1/3$ at $\gsim 3 n_{0}$ . These properties are confronted with the recent observations in superallowed Gamow-Teller transitions and in astrophysical observations.
nucl-thastro-ph.HEhep-ph17 citations
03
Signature of $N^{⋆}$ resonance in mass spectrum of the $K K ˉ N$ decay channels
Sajjad Marri🇮🇷
Three-body calculations of $I = \frac{1}{2}$ , $J^{π} = \frac{1}{2}^{+}$ state of $K K ˉ N$ system were performed. Using separable potentials for two-body interactions in the Faddeev equation, different reaction process for $K K ˉ N$ three-body system were studied. Within this method, the $π Σ K$ and $π η N$ mass spectra were extracted. Different types of $K ˉ N - π Σ$ potentials based on phenomenological and chiral SU(3) approach were used and the dependence of the mass spectra to the $K ˉ N$ model of interaction were studied. It was shown that the $π Σ K$ and $π η N$ mass spectra could be a useful tool to study the properties of the $N^{⋆}$ resonance.
nucl-thPRC(2020)·3 citations
04
Jet quenching parameter from a soft wall AdS/QCD model
Xiangrong Zhu🇨🇳 · Zi-qiang Zhang🇨🇳
We study the effect of chemical potential and nonconformality on the jet quenching parameter in a holographic QCD model with conformal invariance broken by a background dilaton. It turns out that the presence of chemical potential and nonconformality both increase the jet quenching parameter thus enhancing the energy loss, consistently with the findings of the drag force.
nucl-thCPC(2020)·5 citations
05
Global polarization in heavy-ion collisions based on axial vortical effect
Yu. B. Ivanov🇷🇺
Global polarization of $Λ$ and $Λ ˉ$ is calculated based on the axial vortical effect (AVE). Simulations are performed within the model of the three-fluid dynamics. Equations of state with the deconfinement transition result in a good agreement with STAR data for both $Λ$ and $Λ ˉ$ polarization, in particular, with the $Λ$ - $Λ ˉ$ splitting. Suppression of the gravitational-anomaly contribution required for the data reproduction is in agreement with predictions of the QCD lattice simulations. Predictions for the global polarization in forthcoming experiments at lower collision energies are made. These forthcoming data will provide a critical test for the AVE and thermodynamic mechanisms of the polarization.
nucl-thhep-phPRC(2020)·20 citations
06
Bayesian Analysis of the $^{70}$ Zn $(d,^{3} He)^{69}$ Cu Transfer Reaction
C. Marshall🇺🇸 · P. Morfouace🇫🇷 · N. de Séréville🇫🇷 · R. Longland🇺🇸
Transfer reactions provide information about the single-particle nature of nuclear levels. In particular, the differential cross sections from these measurements are sensitive to the angular momentum of the transferred particle and the spectroscopic factor of the populated level. However, the process of extracting these properties is subject to uncertainties, both from experimental and theoretical sources. By integrating the distorted wave Born approximation into a Bayesian model, we propagate these uncertainties through to the spectroscopic factors and orbital angular momentum values. We use previously reported data of the proton pickup reaction $^{70}$ Zn $(d,^{3} He)^{69}$ Cu as an example. By accounting for uncertainties in the experimental data, optical model parameters, and reaction mechanism, we find that the extracted spectroscopic factors for low lying states of $^{69}$ Cu are subject to large, asymmetric uncertainties ranging from $35%$ to $108%$ . Additionally, Bayesian model comparison is employed to assign probabilities to each of the allowed angular momentum transfers. This method confirms the assignments for many states, but suggests that the data for a state lying at $3.70$ MeV is better characterized by an $ℓ = 3$ transfer, rather than the previously reported $ℓ = 2$ .
nucl-thPRC(2020)·9 citations
07
Higgs modulation of emergent mass as revealed in kaon and pion parton distributions
Zhu-Fang Cui🇨🇳 · Minghui Ding🇮🇹 · Fei Gao🇩🇪 · Khepani Raya🇨🇳 · Daniele Binosi🇮🇹 · Lei Chang🇨🇳 · Craig D. Roberts🇨🇳 · Jose Rodriguez-Quintero🇪🇸 · Sebastian M. Schmidt🇩🇪
Strangeness was discovered roughly seventy years ago, lodged in a particle now known as the kaon, $K$ . Kindred to the pion, $π$ ; both states are massless in the absence of Higgs-boson couplings. Kaons and pions are Nature's most fundamental Nambu-Goldstone modes. Their properties are largely determined by the mechanisms responsible for emergent mass in the standard model, but modulations applied by the Higgs are crucial to Universe evolution. Despite their importance, little is known empirically about $K$ and $π$ structure. This study delivers the first parameter-free predictions for all $K$ distribution functions (DFs) and comparisons with the analogous $π$ distributions, i.e. the one-dimensional maps that reveal how the light-front momentum of these states is shared amongst the gluons and quarks from which they are formed. The results should stimulate improved analyses of existing data and motivate new experiments sensitive to all $K$ and $π$ DFs.
↳ hep-phhep-exhep-latnucl-ex+1EPJA(2021)·54 citations
08
Novel dynamic critical phenomena induced by superfluidity and the chiral magnetic effect in Quantum Chromodynamics
Noriyuki Sogabe🇯🇵
In this thesis, we study the novel dynamic critical phenomena induced by superfluidity and the chiral magnetic effect in Quantum Chromodynamics (QCD), respectively. In particular, we find the new dynamic universality class of the high-density QCD critical point between the nuclear and quark superfluid phases beyond the conventional Hohnenberg and Halperin's classification. We also consider the second-order chiral phase transition under an external magnetic field and find that the inclusion of the chiral magnetic effect changes the dynamic universality class from the model E into model A within the conventional classification.
↳ hep-phhep-thnucl-th0 citations
09
Nuclear Reaction Screening, Weak Interactions, and r-Process Nucleosynthesis in High Magnetic Fields
Michael Famiano🇺🇸 · A. Baha Balantekin🇯🇵 · Toshitaka Kajino🇯🇵 · Motohiko Kusakabe🇨🇳 · Kanji Mori🇯🇵 · Yudong Luo🇯🇵
Coulomb screening and weak interactions in a hot, magnetized plasma are investigated. Coulomb screening is evaluated in a relativistic thermal plasma in which electrons and positrons are in equilibrium. In addition to temperature effects, effects on weak screening from a strong external magnetic field are evaluated. In high fields, the electron transverse momentum components are quantized into Landau levels. The characteristic plasma screening length at high temperatures and at high magnetic fields is explored. In addition to changes to the screening length, changes in weak interaction rates are estimated. It is found that high fields can result in increased $β$ -decay rates as the electron and positron spectra are dominated by Landau levels. Finally, the effects studied here are evaluated in a simple r-process model. It is found that relativistic Coulomb screening has a small effect on the final abundance distribution. While changes in weak interaction rates in strong magnetic fields can have an effect on the r-process evolution and abundance distribution, the field strength required to have a significant effect may be larger than what is currently thought to be typical of the r-process environment in collapsar jets or neutron star mergers. If r-process sites exist in fields $≳ 1 0^{14}$ G effects from fields on weak decays could be significant.
↳ astro-ph.HEastro-ph.COnucl-thApJ(2020)·21 citations
10
Relaxation time approximation with pair production and annihilation processes
Samapan Bhadury🇮🇳 · Wojciech Florkowski🇵🇱 · Amaresh Jaiswal🇮🇳 · Radoslaw Ryblewski🇵🇱
We extend the Boltzmann equation in the relaxation time approximation to explicitly include transitions between particles forming an interacting mixture. Using the detailed balance condition as well as conditions of energy-momentum and current conservation, we show that only two independent relaxation time scales are allowed in such an interacting system. Dissipative hydrodynamic equations and the form of transport coefficients is subsequently derived for this case. We find that the shear and bulk viscosity coefficients, as well as the baryon charge conductivity are independent of the transition time scale. However, the bulk viscosity and conductivity coefficients that can be attributed to the individual components of the mixture depend on the transition time.
↳ hep-phhep-thnucl-thPRC(2020)·18 citations
11
Thermal radiation and inclusive production in the running coupling $k_{T}$ -- factorization approach
A. V. Giannini🇧🇷 · V.P. Goncalves🇧🇷 · P.V.R.G. Silva🇧🇷
The characteristics of the thermal radiation are investigated using a two - component model, with the hard component being described by the Color Glass Condensate formalism. The inclusive transverse momentum spectra of charged hadrons produced in proton - proton and proton - nucleus collisions at LHC energies and large - $p_{T}$ are estimated using the running coupling $k_{T}$ - factorization formula and the solution of the Balitsky - Kovchegov equation. Our results indicate that the thermal term is necessary to describe the experimental data and that the effective thermal temperature has an energy dependence similar to the saturation scale. We demonstrate that the enhancement of the thermal temperature in $pP b$ collisions is consistent with that predicted by the saturation scale.
↳ hep-phnucl-thEPJA(2021)·4 citations
12
Modifications on parameters of $Z (4430)$ in a dense medium
K. Azizi🇮🇷 · N. Er🇹🇷
The charmonium-like resonance $Z_{c} (3900)$ and its excited state $Z (4430)$ are among the particles that are serious candidates for double heavy tetraquarks. Calculations of different parameters associated with these states both in the vacuum and the medium with finite density are of great importance. Such investigations help us clarify their nature, internal quark-gluon organization and quantum numbers. In this accordance, we extend our previous analyses on the ground state $Z_{c} (3900)$ to investigate the medium modifications on different parameters of the excited $Z (4430)$ state. In particular, we calculate the mass, vector self-energy and current coupling of $Z (4430)$ in terms of density, up to a density comparable to the density of the cores of massive neutron stars. The obtained results may help experimental groups aiming to study the behavior of exotic states at higher densities.
↳ hep-phhep-exhep-latnucl-thPLB(2020)·10 citations
13
Masses of fully heavy tetraquarks $QQ Q ˉ Q ˉ$ in an extended relativized quark model
Qi-Fang Lü🇨🇳 · Dian-Yong Chen🇨🇳 · Yu-Bing Dong🇨🇳
Inspired by recent measurement of possible fully charmed tetraquarks in LHCb Collaboration, we investigate the mass spectra of fully heavy tetraquarks $QQ Q ˉ Q ˉ$ in an extended relativized quark model. Our estimations indicate that the broad structure around 6.4 GeV should contain one or more ground $cc c ˉ c ˉ$ tetraquark states, while the narrow structure near 6.9 GeV can be categorized as the first radial excitation of $cc c ˉ c ˉ$ system. Moreover, with the wave functions of the tetraquarks and mesons, the strong decays of tetraquarks into heavy quarkonium pair are qualitatively discussed, which can be further checked by the LHCb and CMS Collaborations.
↳ hep-phhep-exnucl-thEPJC(2020)·164 citations
14
The thermodynamics of large-N QCD and the nature of metastable phases
Thomas D. Cohen🇺🇸 · Scott Lawrence🇺🇸 · Yukari Yamauchi🇺🇸
In the limit of a large number of colors (N), both Yang-Mills and quantum chromodynamics are expected to have a first-order phase transition separating a confined hadronic phase and a deconfined plasma phase. One aspect of this separation is that at large N, one can unambiguously identify a plasma regime that is strongly coupled. The existence of a first-order transition suggests that the hadronic phase can be superheated and the plasma phase supercooled. The supercooled deconfined plasma present at large N, if it exists, has the remarkable property that it has negative absolute pressure -- i.e. a pressure below that of the vacuum. For energy densities of order unity in a 1/N expansion but beyond the endpoint of the hadronic superheated phase, a description of homogeneous matter composed of ordinary hadrons with masses of order unity in a 1/N expansion can exist, and acts as though it has a temperature of $T_{H}$ in order unity. However, the connection between the canonical and microcanonical descriptions breaks down and the system cannot fully equilibrate as $N \to \infty$ . Rather, in a hadronic description, energy is pushed to hadrons with masses that are arbitrarily large. The thermodynamic limit of large volumes becomes subtle for such systems: the energy density is no longer intensive. These conclusions follow provided that standard large N scaling rules hold, the system at large N undergoes a generic first-order phase transition between the hadronic and plasma phases and that the mesons and glueballs follow a Hagedorn-type spectrum.
↳ hep-phhep-thnucl-thPRC(2020)·3 citations
15
A novel formulation of the unintegrated gluon distribution for DIS
Renaud Boussarie🇺🇸 · Yacine Mehtar-Tani🇺🇸
We provide a semi-classical description of the inclusive gluon induced Deep Inelastic Scattering cross section in a way that accounts for the leading powers in both the Regge and Bjorken limits. Our approach thus allows a systematic matching of small and moderate $x_{Bj}$ regimes of gluon proton structure functions. We find a new unintegrated gluon distribution with an explicit dependence on the longitudinal momentum fraction $x$ which entirely spans both the dipole operator and the gluonic Parton Distribution Function. Computing this gauge invariant gluon operator on the lattice could allow to probe the energy dependence of the saturation scale from first principles.
↳ hep-phnucl-thPLB(2022)·49 citations
16
A lower bound on the maximum mass if the secondary in GW190814 was once a rapidly spinning neutron star
Elias R. Most · L. Jens Papenfort · Lukas R. Weih · Luciano Rezzolla
The recent detection of GW190814 featured the merger of a binary with a primary having a mass of $\sim 23 M_{⊙}$ and a secondary with a mass of $\sim 2.6 M_{⊙}$ . While the primary was most likely a black hole, the secondary could be interpreted as either the lightest black hole or the most massive neutron star ever observed, but also as the indication of a novel class of exotic compact objects. We here argue that the secondary in GW190814 needs not be an ab-initio black hole nor an exotic object; rather, based on our current understanding of the nuclear-matter equation of state, it can be a rapidly rotating neutron star that collapsed to a rotating black hole at some point before merger. Using universal relations connecting the masses and spins of uniformly rotating neutron stars, we estimate the spin, $0.49 ≲ χ ≲ 0.68$ , of the secondary -- a quantity not constrained so far by the detection -- and a novel strict lower bound on the maximum mass, $M_{TOV} > 2.0 8_{- 0.04}^{+ 0.04} M_{⊙}$ , of nonrotating neutron stars, consistent with recent observations of a very massive pulsar. The new lower bound also remains valid even in the less likely scenario in which the secondary neutron star never collapsed to a black hole.
↳ astro-ph.HEgr-qcnucl-thMNRAS(2020)·178 citations

Affiliations

first authorsco-authorsvia INSPIRE