Nuclear Theory·nucl-th

Tuesday·July 19, 2022

9 papers—2 primary·7 cross-listed

01
Nuclear excitation cross section of $^{229}$ Th via inelastic electron scattering
Hanxu Zhang · Wu Wang · Xu Wang
Nuclear excitation cross section of $^{229}$ Th from the ground state to the low-lying isomeric state via inelastic electron scattering is calculated, on the level of Dirac distorted wave Born approximation. With electron energies below 100 eV, inelastic scattering is very efficient in the isomeric excitation, yielding excitation cross sections on the order of 10 $^{- 27}$ to 10 $^{- 26}$ cm $^{2}$ . Systematic analyses are presented on elements affecting the excitation cross section, including the ion-core potential, the relativistic effect, the knowledge of the reduced nuclear transition probabilities, etc.
nucl-thPRC(2022)·26 citations
02
Effective shear and bulk viscosities of the quark-gluon plasma: QCD versus heavy-ion data
Fernando G. Gardim🇧🇷 · Jean-Yves Ollitrault🇫🇷
In recent years, there has been a significant effort to extract the temperature-dependent shear ( $η / s$ ) and bulk ( $ζ / s$ ) viscosity over entropy ratios of the quark-gluon plasma from a global comparison of heavy-ion data with results of hydrodynamic simulations. However, anisotropic flow, which is arguably the most sensitive probe of viscosity, is only sensitive to an {\it effective\/} viscosity over entropy ratio, which is obtained by taking a weighted average over the temperature, and summing the contributions of shear and bulk. We estimate this effective viscosity using existing first-principles calculations, which give $0.17 < (η / s)_{eff} < 0.21$ , and $(ζ / s)_{eff} < 0.08$ , implying that the damping of anisotropic flow at the LHC is mostly due to shear viscosity. The values extracted from global data analyses are compatible with these theory predictions.
nucl-thhep-phnucl-exActa Phys.Polon.Supp.(2023)·3 citations
03
Jets in evolving matter within the opacity expansion approach
Andrey V. Sadofyev🇪🇸 · Matthew D. Sievert🇺🇸 · Ivan Vitev🇺🇸
In a recent study [1] we have extended the opacity expansion approach to describe jet-medium interactions including medium motion effects in the context of heavy-ion collisions. We have computed color field of the in-medium sources, including the effects of the transverse field components and the energy transfer between the medium and jet. The corresponding contributions are sub-eikonal in nature, and were previously ignored in the literature. Here we discuss how our approach can be applied to describe the medium motion effects in the context of Deep Inelastic Scattering.
↳ hep-phnucl-thSciPost Phys.Proc.(2022)·10 citations
04
Far-from-equilibrium kinetic dynamics of $λ ϕ^{4}$ theory in an expanding universe
Nicki Mullins (Illinois U., Urbana)🇺🇸 · Gabriel S. Denicol (Niteroi, Fluminense U.)🇧🇷 · Jorge Noronha (Illinois U., Urbana)🇺🇸
We investigate the far-from-equilibrium behavior of the Boltzmann equation for a gas of massless scalar field particles with quartic (tree level) self-interactions ( $λ ϕ^{4}$ ) in Friedmann-Lemaitre-Robertson-Walker spacetime. Using a new covariant generating function for the moments of the Boltzmann distribution function, we analytically determine a subset of the spectrum and the corresponding eigenfunctions of the linearized Boltzmann collision operator. We show how the covariant generating function can be also used to find the exact equations for the moments in the full nonlinear regime. Different than the case of a ultrarelativistic gas of hard spheres (where the total cross section is constant), for $λ ϕ^{4}$ the fact that the cross section decreases with energy implies that moments of arbitrarily high order directly couple to low order moments. Numerical solutions for the scalar field case are presented and compared to those found for a gas of hard spheres.
↳ hep-phgr-qcnucl-thPRD(2022)·18 citations
05
The $X (3960)$ seen in $D_{s}^{+} D_{s}^{-}$ as the $X (3930)$ state seen in $D^{+} D^{-}$
M. Bayar🇹🇷 · A. Feijoo🇪🇸 · E. Oset🇪🇸
We perform a calculation of the interaction of the $D D ˉ$ , $D_{s} D ˉ_{s}$ coupled channels and find two bound states, one coupling to $D D ˉ$ and another one at higher energies coupling mostly to $D_{s}^{+} D_{s}^{-}$ . We identify this latter state with the $X_{0} (3930)$ seen in the $D^{+} D^{-}$ mass distribution in the $B^{+} \to D^{+} D^{-} K^{+}$ decay, and also show that it produces an enhancement of the $D_{s}^{+} D_{s}^{-}$ mass distribution close to threshold which is compatible with the LHCb recent observation in the $B^{+} \to D_{s}^{+} D_{s}^{-} K^{+}$ decay which has been identified as a new state, $X_{0} (3960)$ .
↳ hep-phnucl-thPRD(2023)·35 citations
06
Liénard-Wiechert potential of a heavy quark moving in QGP medium
Jobin Sebastian🇮🇳 · Mohammad Yousuf Jamal🇮🇳 · Najmul Haque🇮🇳
We investigate the nature of the complex retarded potential of a heavy quarkonium moving in a hot and dense static deconfined nuclear medium. The well-known concept of the retarded potential in electrodynamics is extended to the context of the heavy-quark by modifying the static vacuum Cornell potential through Lorentz transformation to the static frame of the medium. The resulting potential in the vacuum is further corrected to incorporate the screening effect offered by the thermal medium. To do so, the retarded Cornell potential is modified by the dielectric function of the static quark-gluon plasma (QGP) medium. We present the numerical results for the real and imaginary parts of the potential along with the analytical expression of the potential approximated by a small velocity limit. Finally, we present the thermal width of quarkonia in the QGP medium derived using the imaginary part of the potential and study its dependence on velocity and temperature.
↳ hep-phnucl-thPRD(2023)·16 citations
07
Stability and instability of strange dwarfs
Francesco Di Clemente (Ferrara University and INFN Sez. Ferrara)🇮🇹 · Alessandro Drago (Ferrara University and INFN Sez. Ferrara)🇮🇹 · Prasanta Char (STAR Institute, University of Liege)🇧🇪 · Giuseppe Pagliara (Ferrara University and INFN Sez. Ferrara)🇮🇹
More than 20 years ago, Glendenning, Kettner and Weber proposed the existence of stable white dwarfs with a core of strange quark matter. More recently, by studying radial modes, Alford, Harris and Sachdeva concluded instead that those objects are unstable. We aim to clarify this issue. We investigate the stability of these objects by looking at their radial oscillations while incorporating boundary conditions at the quark-hadron interface, corresponding to either a rapid or a slow conversion of hadrons into quarks. Our analysis shows that objects of this type are stable if the star is not strongly perturbed, and ordinary matter cannot transform into strange quark matter because of the Coulomb barrier separating the two components. On the other hand, ordinary matter can be transformed into strange quark matter if the star undergoes a violent process, as in the preliminary stages of a type Ia supernova, and this causes the system to become unstable and to collapse into a strange quark star. In this way, accretion-induced collapse of strange dwarfs can be facilitated, and km-sized objects with subsolar masses can be produced.
↳ astro-ph.SRastro-ph.HEhep-phnucl-thAstron.Astrophys.(2023)·16 citations
08
On the robustness of solitons crystals in the Skyrme model
Gonzalo Barriga🇨🇱 · Fabrizio Canfora🇨🇱 · Marcela Lagos🇨🇱 · Matías Torres🇨🇱 · Aldo Vera🇨🇱
In this work we analize how the inclusion of extra mesonic degrees of freedom affect the finite density solitons crystals of the Skyrme model. In particular, the first analytic examples of hadronic crystals at finite baryon density in both the Skyrme $ω$ -mesons model as well as for the Skyrme $ρ$ -mesons theory are constructed. These configurations have arbitrary topological charge and describe crystals of baryonic tubes surrounded by a cloud of vector-mesons. In the $ω$ -mesons case, it is possible to reduce consistently the complete set of seven coupled non-linear field equations to just two integrable differential equations; one ODE for the Skyrmion profile and one PDE for the $ω$ -mesons field. This analytical construction allows to show explicitly how the inclusion of $ω$ -mesons in the Skyrme model reduces the repulsive interaction energy between baryons. In the Skyrme $ρ$ -mesons case, it is possible to construct analytical solutions using a meron-type ansatz and fixing one of the couplings of the $ρ$ -mesons action in terms of the others. We show that, quite remarkably, the values obtained for the coupling constants by requiring the consistency of our ansatz are very close to the values used in the literature to reduce nuclei binding energies of the Skyrme model without vector-mesons. Moreover, our analytical results are in qualitative agreement with the available results on the nuclear spaghetti phase.
↳ hep-thastro-ph.HEhep-phnucl-thNPB(2022)·7 citations
09
Towards the determination of the gluon helicity distribution in the nucleon from lattice quantum chromodynamics
Colin Egerer🇺🇸 · Bálint Joó🇺🇸 · Joseph Karpie🇺🇸 · Nikhil Karthik🇺🇸 · Tanjib Khan🇧🇩 · Christopher J. Monahan🇺🇸 · Wayne Morris🇺🇸 · Kostas Orginos🇺🇸 · Anatoly Radyushkin🇺🇸 · David G. Richards🇺🇸 · Eloy Romero🇺🇸 · Raza Sabbir Sufian🇺🇸 · Savvas Zafeiropoulos🇫🇷
We present the first exploratory lattice quantum chromodynamics (QCD) calculation of the polarized gluon Ioffe-time pseudo-distribution in the nucleon. The Ioffe-time pseudo-distribution provides a frame-independent and gauge-invariant framework to determine the gluon helicity in the nucleon from first principles. We employ a high-statistics computation using a $3 2^{3} \times 64$ lattice ensemble characterized by a $358$ MeV pion mass and a $0.094$ fm lattice spacing. We establish the pseudo-distribution approach as a feasible method to address the proton spin puzzle with successive improvements in statistical and systematic uncertainties anticipated in the future. Within the statistical precision of our data, we find a good comparison between the lattice determined polarized gluon Ioffe-time distribution and the corresponding expectations from the state-of-the-art global analyses. We find a hint for a nonzero gluon spin contribution to the proton spin from the model-independent extraction of the gluon helicity pseudo-distribution over a range of Ioffe-time, $ν ≲ 9$ .
↳ hep-lathep-phnucl-thPRD(2022)·50 citations

Affiliations

first authorsco-authorsvia INSPIRE