Nuclear Theory·nucl-th

Tuesday·February 13, 2024

16 papers—9 primary·7 cross-listed

01
Reply to the "Comments to the paper "Detailed study of the astrophysical direct capture reaction $^{6} Li (p, γ)^{7} Be$ in ..." " by S.B. Dubovichenko, A.S. Tkachenko, R. Ya. Kezerashvili, arXiv:2401.04281 (2024)
E.M. Tursunov · S.A. Turakulov · K.I. Tursunmakhatov
The differences in potential models used in our work and in the original paper of the authors of the Comment are discussed. The neglecting of simple rules of reaction calculations is shown as a possible origin of the defect in the temperature dependence of the reaction rates in the work of the authors of the Comment.
nucl-thastro-ph.SR0 citations
02
Detecting anomalous CP violation in heavy ion collisions through baryon-electric charge correlations
David Frenklakh🇺🇸 · Dmitri E. Kharzeev🇺🇸 · Andrea Palermo🇺🇸
The chiral magnetic effect (CME) and the chiral vortical effect (CVE) induce a correlation between baryon and electric currents. We show that this correlation can be detected using a new observable: a mixed baryon-electric charge correlator. This correlator is proportional to the baryon asymmetry, suggesting a novel way to separate the chiral effects from the background in heavy ion collisions.
nucl-thPRD(2024)·3 citations
03
Radiative neutron capture rate of $^{11}$ B $(n, γ)^{12}$ B reaction from the Coulomb dissociation of $^{12}$ B
Shubhchintak · G. Singh · R. Chatterjee · M. Dan
We calculate the $^{11}$ B $(n, γ)^{12}$ B reaction rate, an important constituent in nucleosynthesis networks, contributed by resonant as well as non-resonant capture. For the resonant rate, we use the narrow resonance approximation whereas the non-resonant contribution is calculated with the Coulomb dissociation method for which we use finite-range distorted wave Born approximation theory. We then compare our calculated rate of $^{11}$ B $(n, γ)^{12}$ B reaction with those reported earlier and with other charged particle reactions on $^{11}$ B.
nucl-thFew Body Syst.(2024)·3 citations
04
Consistent inclusion of fluctuations in first-order causal and stable relativistic hydrodynamics
Lorenzo Gavassino🇺🇸 · Nicki Mullins🇺🇸 · Mauricio Hippert🇺🇸
We construct, for the first time, a Bemfica-Disconzi-Noronha-Kovtun (BDNK) theory for linear stochastic fluctuations, which is proved to be mathematically consistent, causal, and covariantly stable. The Martin-Siggia-Rose action is shown to be bilocal in most cases, and the noise is not white. The presence of nonhydrodynamic modes induces long-range correlations in the primary fluid variables (temperature, chemical potential, and flow velocity). However, correlators of conserved densities remain localized in space, and coincide with those calculated within fluctuating Isreal-Stewart theory. We show that, in some cases, there is a nonlocal change of variables that maps the Israel-Stewart action into the BDNK action.
nucl-thgr-qchep-thPRD(2024)·15 citations
05
Second-Order Transport Coefficients in Neutron Star Mergers
Yumu Yang · Mauricio Hippert · Enrico Speranza · Jorge Noronha
In neutron stars, flavor-changing weak interactions determine the equilibrium fraction of protons over neutrons. In binary neutron-star mergers, violent changes in density modify this equilibrium value at timescales of milliseconds, comparable to those required for weak interactions to take place. As a result, the fraction of protons evolves out of phase with the density oscillations, giving rise to irreversible processes. The corresponding shift in pressure leads to dissipative work that can be modeled as an effective bulk-viscous correction. In this work, we derive the relevant equations of motion of Israel-Stewart hydrodynamics within this context. Using a toy model, we compute the second-order transport coefficients. Finally, we comment on the use of a realistic equation of state. Our results are expected to be useful for the study of viscous effects in numerical simulations of binary mergers.
nucl-thastro-ph.HEhep-ph1 citation
06
Examination of the $ϕ - N N$ bound-state problem with lattice QCD $N - ϕ$ potentials
Faisal Etminan🇮🇷 · Amanullah Aalimi🇮🇷
The developed Faddeev three-body equations are solved to search for bound-state solutions of a phi-meson $(ϕ)$ and two nucleons $(NN)$ system. The newly published spin $3/2$ $N- \ensuremath \phi$ potential based on the $(2+1)$ -flavor lattice QCD simulations near physical point, and realistic $NN$ Malfliet-Tjon (MT) potential, are employed. Our numerical calculations for $(I) J^{π} = (0) 2^{-}$ $ϕ -d$ system in maximum spin leads to ground state binding energy of about $7$ MeV and a matter radius of about $8$ fm. Our results indicates the possibility of the formation of new nuclear clusters.
nucl-thPRC(2024)·16 citations
07
Transport coefficients of transient hydrodynamics for the hadron-resonance gas and thermal-mass quasiparticle models
Gabriel S. Rocha🇺🇸 · Gabriel S. Denicol🇧🇷
We calculate all transport coefficients of second order transient hydrodynamics in two effective kinetic theory models: a hadron-resonance gas and a quasiparticle model with thermal masses tuned to reproduce QCD thermodynamics. We compare the corresponding results with calculations for an ultrarelativistic single-component gas, that are widely employed in hydrodynamic simulations of heavy ion collisions. We find that both of these effective models display a qualitatively different normalized bulk viscosity, when compared to the calculation for the single-component gas. Indeed, $ζ / [τ_{Π} (ε_{0} + P_{0})] ≃ 16.91 (1/3 - c_{s}^{2})^{2}$ , for the hadron-resonance gas model, and $ζ / [τ_{Π} (ε_{0} + P_{0})] ≃ 5 (1/3 - c_{s}^{2})$ for the quasiparticle model. Differences are also observed for many second-order transport coefficients, specially those related to the bulk viscous pressure. The transport coefficients derived are shown to be consistent with fundamental linear stability and causality conditions.
nucl-thhep-phPRD(2024)·9 citations
08
"To renormalize or not to renormalize ?'' in the proton-deuteron scattering calculations
H. Witała · J. Golak · R. Skibiński
We discuss two approaches which, by applying the screening method, permit one to include the long range proton-proton (pp) Coulomb force in proton-deuteron (pd) momentum-space scattering calculations. In the first one, based on Alt-Grassberger-Sandhas (AGS) equation, presented in Phys. Rev. C{\bf{71}}, 054005 (2005) and {\bf{73}}, 057001 (2006), one needs to renormalize elastic scattering amplitude before calculating observables. In the second treatment, proposed by us in Eur. Phys. Journal A {\bf{41}}, 369 (2009), {\bf{41}}, 385 (2009), and arXiv:2310.03433 [nucl.th], this renormalization is avoided. For the proton induced deuteron breakup reaction both approaches require renormalization of the corresponding transition amplitudes. We derive the basic equations underlying both methods under the assumption that all contributing partial wave states are included and explain why in our approach renormalization of the elastic scattering amplitude is superfluous. We show that in order to take into account in the screening limit all partial waves it is required that four additional terms, based on the 3-dimensional and partial-wave projected pp Coulomb t-matrices, identical for both approaches, must appear in transition amplitudes. We investigate importance of these terms for elastic pd scattering below the breakup threshold.
nucl-th0 citations
09
Statistical analysis of the fluctuations of an initial-state model with independently distributed hot spots
Nicolas Borghini🇩🇪 · Hendrik Roch🇩🇪 · Alicia Schütte🇩🇪
We determine the uncorrelated modes that characterize the fluctuations in a semi-realistic model for the initial state of high-energy nuclear collisions, consisting of hot spots whose positions are distributed independently. Varying the number of hot spots, their size, and the weights with which they contribute to the initial state, we find that the parameter that has the largest influence on the relative importance of the fluctuation modes is the source size, with more extended hot spots leading to a more marked predominance of the principal modes.
nucl-thhep-phEPJC(2025)·4 citations
10
Determination of the Collins-Soper kernel from Lattice QCD
Artur Avkhadiev🇺🇸 · Phiala E. Shanahan🇺🇸 · Michael L. Wagman🇺🇸 · Yong Zhao🇺🇸
This work presents a determination of the quark Collins-Soper kernel, which relates transverse-momentum-dependent parton distributions (TMDs) at different rapidity scales, using lattice quantum chromodynamics (QCD). This is the first such determination with systematic control of quark mass, operator mixing, and discretization effects. Next-to-next-to-leading logarithmic matching is used to match lattice-calculable distributions to the corresponding TMDs. The continuum-extrapolated lattice QCD results are consistent with several recent phenomenological parameterizations of the Collins-Soper kernel and are precise enough to disfavor other parameterizations.
↳ hep-lathep-phnucl-thPRL(2024)·66 citations
11
Flavor Factorization at Two-Loops
Andrew J. Larkoski🇺🇸
Recently, a factorization theorem was proposed for partonic flavor evolution as defined by the net flavor of the Winner-Take-All axis of a jet. We validate the factorization theorem through explicit calculation at two-loop order, and in the process extract all anomalous dimensions and renormalization factors for any ultraviolet-to-infrared flavor transition at this order. These results can then be used to extract the renormalized hard function for flavored jet production at next-to-next-to-leading order for any process of interest.
↳ hep-phhep-exnucl-exnucl-thEPJC(2024)·2 citations
12
Study on the $ϕ$ -meson photoproduction off the proton target with the pentaquark-like $K^{*} Σ$ bound state $P_{s}$
Sang in Shim🇯🇵 · Yongsun Kim🇰🇷 · Seung-il Nam🇰🇷
We utilize the effective Lagrangian method within the tree-level Born approximation to explore $ϕ$ -meson photoproduction, i.e., $γ p \to ϕp$ . Our analysis encompasses contributions from various sources, including the Pomeron, $f_{1}$ -Regge, pseudoscalar particles ( $π$ , $η$ ), scalar particles ( $a_{0}$ , $f_{0}$ ), protons, and three-nucleon resonance states. In addition, we consider a possible pentaquark-like $K^{*} Σ$ -bound state $P_{s}$ . The findings indicate that, apart from the region near the threshold, contributions other than the Pomeron generally have a limited impact on the total cross section. However, at specific angles, alternative contributions become crucial, particularly at smaller values of $cos θ$ . The incorporation of $P_{s}$ and other nucleon resonances proves essential to elucidate the bump observed near $W \sim 2.15$ GeV at very forward angles and behaviors within the range of $W = (2.0 - 2.3)$ GeV. Furthermore, in the region with $W \geq 2.5$ GeV, where nucleon resonances become negligible, contributions from the t-channel mesons become pivotal. Our calculations for spin density matrix components, examined in various frames, exhibit improvement when considering all contributions. This comprehensive approach successfully reproduces the observed bump by including $P_{s}$ . We also briefly estimate the $P_{s}$ production via $ϕ$ -meson photoproduction in the future Electron-Ion Collider (EIC), resulting in the luminosity of 10 fb $^{- 1}$ per month.
↳ hep-phnucl-thMod.Phys.Lett.A(2024)·4 citations
13
Pearcey integrals, Stokes lines and exact baryonic layers in the low energy limit of QCD
Sergio L. Cacciatori🇮🇹 · Fabrizio Canfora🇨🇱 · Federica Muscolino🇨🇱
The first analytic solutions representing baryonic layers living at finite baryon density within a constant magnetic field in the gauged Skyrme model are constructed. A remarkable feature of these configurations is that, if the Skyrme term is neglected, then these baryonic layers in the constant magnetic background cannot be found analytically and their energies grow very fast with the magnetic field. On the other hand, if the Skyrme term is taken into account, the field equations can be solved analytically and the corresponding solutions have a smooth limit for large magnetic fields. Thus, the Skyrme term discloses the universal character of these configurations living at finite Baryon density in a constant magnetic field. The classical gran-canonical partition function of these configurations can be expressed explicitly in terms of the Pearcey integral. This fact allows us to determine analytically the Stokes lines of the partition function and the corresponding dependence on the baryonic chemical potential as well as on the external magnetic field. In this way, we can determine various critical curves in the ( $μ_{B} - B_{e x t}$ ) plane which separates different physical behaviors. These families of inhomogeneous baryonic condensates can be also dressed with chiral conformal excitations of the solutions representing modulations of the layers themselves. Some physical consequences are analyzed.
↳ hep-thhep-phnucl-thNPB(2024)·7 citations
14
Nucleon electric and magnetic polarizabilities in Holographic QCD
Federico Castellani🇮🇹
We analyze the resonance contributions to the generalized Baldin sum rule, namely the sum of the generalized electric and magnetic nucleon polarizabilities $α_{E} (Q^{2})$ and $β_{M} (Q^{2})$ , within the Holographic QCD model by Witten, Sakai, and Sugimoto (WSS). In particular, we account for the contributions from the first low-lying nucleon resonances with spin 1/2 and 3/2 and both parities. After having extrapolated the WSS model parameters to fit experimental data on baryonic observables, we compare our findings with alternative predictions in literature, finding a qualitative agreement with all of them. Moreover, at least for the proton case, where data are available, our results are in qualitative accordance with resonance contributions extracted from experimental nucleon-resonance helicity amplitudes.
↳ hep-phhep-thnucl-thPRD(2024)·3 citations
15
Quarkonia dissociation at finite magnetic field in the presence of momentum anisotropy
Indrani Nilima🇮🇳 · Mujeeb Hasan🇮🇳 · B. K. Singh🇮🇳 · Mohammad Yousuf Jamal🇮🇳
In this study, we investigate the potential of heavy quarkonia within a magnetized hot QGP medium having finite momentum anisotropy. The phenomenon of inverse magnetic catalysis is introduced into the system, influencing the magnetic field-modified Debye mass and thereby altering the effective quark masses. Concurrently, the impact of momentum anisotropy in the medium is considered that influence the particle distribution in the medium. The thermal decay width and dissociation temperature of quarkonium states, specifically the 1S and 2S states of charmonium and bottomonium, are computed. Our results reveal that both momentum anisotropy and the inverse magnetic catalysis effects play a significant role in modifying the thermal decay width and dissociation temperature of these heavy quarkonia states.
↳ hep-phnucl-thEPJC(2024)·8 citations
16
Jet Suppression and Azimuthal Anisotropy from RHIC to LHC
Yacine Mehtar-Tani🇺🇸 · Daniel Pablos🇪🇸 · Konrad Tywoniuk🇳🇴
Azimuthal anisotropies of high- $p_{T}$ particles produced in heavy-ion collisions are understood as an effect of a geometrical selection bias. Particles oriented in the direction in which the QCD medium formed in these collisions is shorter, suffer less energy loss, and thus, are over-represented in the final ensemble compared to those oriented in the direction in which the medium is longer. In this work we present the first semi-analytical predictions, including propagation through a realistic, hydrodynamical background, of the azimuthal anisotropies for jets, obtaining a quantitative agreement with available experimental data as function of the jet $p_{T}$ , its cone size $R$ and the collisions centrality. Jets are multi-partonic, extended objects and their energy loss is sensitive to substructure fluctuations. This is determined by the physics of color coherence that relates to the ability of the medium to resolve those partonic fluctuations. Namely, color dipoles whose angle is smaller than a critical angle, $θ_{c}$ , are not resolved by the medium and they effectively act as a coherent source of energy loss. We find that jet azimuthal anisotropies have a specially strong dependence on coherence physics due to the marked length-dependence of $θ_{c}$ . By combining our predictions for the collision systems and center of mass energies studied at RHIC and the LHC, covering a wide range of typical values of $θ_{c}$ , we show that the relative size of jet azimuthal anisotropies for jets with different cone-sizes $R$ follow a universal trend that indicates a transition from a coherent regime of jet quenching to a decoherent regime. These results suggest a way forward to reveal the role played by the physics of jet color decoherence in probing deconfined QCD matter.
↳ hep-phnucl-thPRD(2024)·39 citations

Affiliations

first authorsco-authorsvia INSPIRE