Nuclear Theory·nucl-th

Thursday·December 1, 2022

12 papers—5 primary·7 cross-listed

01
Neutron-skin values and matter and neutron radii determined from reaction cross sections of proton scattering on $^{12}$ C, $^{40, 48}$ Ca, $^{58}$ Ni, $^{208}$ Pb
Tomotsugu Wakasa · Shingo Tagami · Jun Matsui · Maya Takechi · Masanobu Yahiro
Very lately, the PREX and the CREX collaboration present skin values, $r_{skin}^{208} (newPREX2) = 0.278 \pm 0.078 (exp) \pm 0.012 (theor.) fm$ and $r_{skin}^{48} = 0.121 \pm 0.026 (exp) \pm 0.024 (model)$ , respectively. We recently determined a neutron-skin value $r_{skin}^{208} = 0.278 \pm 0.035$ fm from measured reaction cross sections $σ_{R} (exp)$ of p+ $^{208}$ Pb scattering in a range of incident energies $10 \lsim E_{in} \lsim 100$ MeV where the chiral (Kyushu) $g$ -matrix folding model is reliable for $^{12}$ C+ $^{12}$ C scattering. The data $σ_{R} (exp)$ are available for proton scattering on $^{58}$ Ni, $^{40, 48}$ Ca, $^{12}$ C targets. Our first aim is to test the Kyushu $g$ -matrix folding model for p+ $^{208}$ Pb scattering in $20 \lsim E_{in} \lsim 180$ MeV. Our second aim is to determine skin values $r_{skin}$ and matter and neutron radii, $r_{m}$ and $r_{n}$ , for $^{208}$ Pb, $^{58}$ Ni, $^{40, 48}$ Ca, $^{12}$ C from the $σ_{R} (exp)$ . Our method is the Kyushu $g$ -matrix folding model with the densities scaled from the D1S-GHFB+AMP densities, where D1S-GHFB+AMP stands for Gogny-D1S HFB (GHFB) with the angular momentum projection (AMP). As for proton scattering, we find that our model is reliable in $20 \lsim E_{in} \lsim 180$ MeV. For $^{208}$ Pb, the skin value deduced from $σ_{R} (exp)$ in $20 \lsim E_{in} \lsim 180$ MeV is $r_{skin}^{208} (σ_{R}) = 0.299 \pm 0.020$ fm. Our results on $r_{skin}$ are compared with the previous works. Our result $r_{skin}^{208} (σ_{R}) = 0.299 \pm 0.020$ fm agrees with $r_{skin}^{208} (PREX2) = 0.283 \pm 0.071$ fm. In addition, our result $r_{skin}^{48} = 0.103 \pm 0.022$ fm is consistent with the CREX value.
nucl-thPRC(2023)·9 citations
02
Medium Response and Jet-Hadron Correlations in Relativistic Heavy-Ion Collisions
Shanshan Cao🇨🇳 · Guang-You Qin🇨🇳
High-energy heavy-ion collisions at the Relativistic Heavy-Ion Collider and the Large Hadron Collider have evolved from qualitative understanding into precise extraction of the properties of the Quantum Chromodynamics medium at extremely high temperature. Jet quenching has offered unique insights into the transport properties of the Quark-Gluon Plasma (QGP) created in these energetic collisions. Apart from medium modification of jets, jet-induced medium excitation constitutes another crucial aspect of jet-QGP interaction, and is indispensable in understanding the soft components of jets. We review recent theoretical and phenomenological developments on medium response to jet energy loss, including an overview of both weakly and strongly coupled approaches for describing the thermalization and propagation of energy deposition from jets, effects of medium response on jet observables, and exploration of its unique signatures in jet-hadron correlations. Jet-induced medium excitation is shown to be an essential component in probing the in-medium dynamics of jets and a critical step towards precise extraction of the QGP properties.
nucl-thhep-phnucl-exAnn.Rev.Nucl.Part.Sci.(2023)·39 citations
03
Lifetime of the hypertriton
D. Gazda🇨🇿 · A. Pérez-Obiol🇪🇸 · A. Gal🇮🇱 · E. Friedman🇮🇱
Conflicting values of the hypertriton lifetime $τ (_{Λ}^{3} H)$ were derived in relativistic heavy ion (RHI) collision experiments over the last decade. A very recent ALICE Collaboration measurement is the only experiment where the reported $τ (_{Λ}^{3} H)$ comes sufficiently close to the free- $Λ$ lifetime $τ_{Λ}$ ,as expected naively for a very weakly bound $Λ$ in $_{Λ}^{3} H$ . We revisited theoretically this $_{Λ}^{3} H$ lifetime puzzle, using $_{Λ}^{3} H$ and $^{3} He$ wave functions computed within the abinitio no-core shell model employing interactions derived from chiral effective field theory to calculate the two-body decay rate $Γ (_{Λ}^{3} H \to^{3} He + π^{-})$ . We found significant but opposing contributions arising from $Σ N N$ admixtures in $_{Λ}^{3} H$ and from $π^{-} -^{3} He$ final-state interaction. To derive $τ (_{Λ}^{3} H)$ , we evaluated the inclusive $π^{-}$ decay rate $Γ_{π^{-}} (_{Λ}^{3} H)$ by using the measured branching ratio $Γ (_{Λ}^{3} H \to^{3} He + π^{-}) / Γ_{π^{-}} (_{Λ}^{3} H)$ and added the $π^{0}$ contributions through the $Δ I = \frac{1}{2}$ rule. The resulting $τ (_{Λ}^{3} H)$ varies strongly with the rather poorly known $Λ$ separation energy $E_{sep} (_{Λ}^{3} H)$ and it is thus possible to associate each one of the distinct RHI $τ (_{Λ}^{3} H)$ measurements with its own underlying value of $E_{sep} (_{Λ}^{3} H)$ .
nucl-thhep-phnucl-exEPJ Web Conf.(2022)·1 citation
04
Predicting Beta Decay Energy with Machine Learning
Jose M. Munoz · Serkan Akkoyun · Zayda P. Reyes · Leonardo A. Pachon
$Q_{β}$ represents one of the most important factors characterizing unstable nuclei, as it can lead to a better understanding of nuclei behavior and the origin of heavy atoms. Recently, machine learning methods have been shown to be a powerful tool to increase accuracy in the prediction of diverse atomic properties such as energies, atomic charges, volumes, among others. Nonetheless, these methods are often used as a black box not allowing unraveling insights into the phenomena under analysis. Here, the state-of-the-art precision of the $β$ -decay energy on experimental data is outperformed by means of an ensemble of machine-learning models. The explainability tools implemented to eliminate the black box concern allowed to identify uncertainty and atomic number as the most relevant characteristics to predict $Q_{β}$ energies. Furthermore, physics-informed feature addition improved models' robustness and raised vital characteristics of theoretical models of the nuclear structure.
nucl-thnucl-exphysics.data-anPRC(2023)·14 citations
05
Vortex rings in heavy-ion collisions at energies $s_{N N} =$ 3--30 GeV and possibility of their observation
Yu. B. Ivanov🇷🇺
The ring structures that appear in Au+Au collisions at collision energies $s_{N N} =$ 3 -- 30 GeV are studied. The calculations are performed within the model of three-fluid dynamics. It is demonstrated that a pare of vortex rings are formed, one at forward and another at backward rapidities, in ultra-central Au+Au collisions at $s_{N N} >$ 4 GeV. The vortex rings carry information about early stage of the collision, in particular about the stopping of baryons. It is shown that these rings can be detected by measuring the ring observable $R_{Λ}$ even in rapidity range $0 < y < 0.5$ (or $- 0.5 < y < 0$ ) on the level of 0.5--1.5\% at $s_{N N} =$ 5 -- 20 GeV. At forward/backward rapidities, the $R_{Λ}$ signal is expected to be stronger. Possibility of observation of the vortex-ring signal against background of non-collective transverse polarization is discussed.
nucl-thhep-phnucl-exPRC(2023)·6 citations
06
Freezing-In Gravitational Waves
Jacopo Ghiglieri🇫🇷 · Jan Schütte-Engel🇺🇸 · Enrico Speranza🇺🇸
The thermal plasma in the early universe produced a stochastic gravitational wave (GW) background, which peaks today in the microwave regime and was dubbed the cosmic gravitational microwave background (CGMB). In previous works only single graviton production processes that contribute to the CGMB have been considered. Here we also investigate graviton pair production processes and show that these can lead to a significant contribution if the ratio between the maximum temperature and the Planck mass, $T_{max} / m_{p}$ , divided by the internal coupling in the heat bath is large enough. As the dark matter freeze-in production mechanism is conceptually very similar to the GW production mechanism from the primordial thermal plasma, we refer to the latter as ``GW freeze-in production''. We show that quantum gravity effects appear in single graviton production and are smaller by a factor $(T_{max} / m_{p})^{2}$ than the leading order contribution. In our work we explicitly compute the CGMB spectrum within a scalar model with quartic interaction.
↳ hep-phastro-ph.COgr-qchep-th+1PRD(2024)·58 citations
07
Strong two-meson decays of light and charmed vector mesons
Roberto Correa da Silveira🇧🇷 · Fernando E. Serna🇧🇷 · Bruno El-Bennich🇧🇷
We calculate the strong decay couplings for $ρ \to π π$ , $ϕ \to K K$ , $K^{*} \to K π$ and $D^{*} \to D π$ in a unified and consistent approach based on the impulse approximation, nonperturbative solutions of the quark-gap equation and the Poincaré invariant Bethe-Salpeter amplitudes of vector and pseudoscalar mesons. In particular, we obtain the coupling $g_{D^{*} D π} = 17.2 4_{- 2.30}^{+ 3.06}$ in very good agreement with the experimental value by CLEO, which corresponds to a strong effective coupling between heavy vector and pseudoscalar mesons to the pion of $g^= 0.5 8_{- 0.08}^{+ 0.10}$ .
↳ hep-phhep-exhep-latnucl-thPRD(2023)·13 citations
08
Dissipative reactions with intermediate-energy beams -- a novel approach to populate complex-structure states in rare isotopes
A. Gade · B. A. Brown · D. Weisshaar · D. Bazin · K. W. Brown · R. J. Charity · P. Farris · A. M. Hill · J. Li · B. Longfellow · D. Rhodes · W. Reviol · J. A. Tostevin
A novel pathway for the formation of multi-particle-multi-hole (np-mh) excited states in rare isotopes is reported from highly energy- and momentum-dissipative inelastic-scattering events measured in reactions of an intermediate-energy beam of 38Ca on a Be target. The negative-parity,complex-structure final states in 38Ca were observed following the in-beam gamma-ray spectroscopy of events in the 9Be(38Ca,38Ca+gamma)X reaction in which the scattered projectile lost longitudinal momentum of order p = 700 MeV/c. The characteristics of the observed final states are discussed and found to be consistent with the formation of excited states involving the rearrangement of multiple nucleons in a single, highly-energetic projectile-target collision. Unlike the far-less dissipative, surface-grazing reactions usually exploited for the in-beam gamma-ray spectroscopy of rare isotopes, these more energetic collisions appear to offer a practical pathway to nuclear-structure studies of more complex multi-particle configurations in rare isotopes - final states conventionally thought to be out of reach with high-luminosity fast-beam-induced reactions.
↳ nucl-exnucl-thPRL(2022)·11 citations
09
Contribution of the Weinberg-type operator to atomic electric dipole moments
Naohiro Osamura🇯🇵
We report the calculation of the isovector CP-odd $π N$ interaction generated by the Weinberg operator, the CP violating three-gluon operator. This enables to restrict models which induce the operator by using experimental data of atomic electric dipole moment. The QCD sum rules are used to determine the matrix element required to assess the CP-odd $π N$ interactions. The relation between the Weinberg operator and the Hg and Xe EDMs is clarified, and the constraint on the Weinberg operator is obtained using the experimental data for the Hg EDM.
↳ hep-phnucl-thphysics.atom-phAIP Conf.Proc.(2024)·0 citations
10
Progress in calculation of the fourth Mellin moment of the pion light-cone distribution amplitude using the HOPE method
William Detmold🇺🇸 · Anthony V. Grebe🇺🇸 · Issaku Kanamori🇯🇵 · C.-J. David Lin🇹🇼 · Robert J. Perry🇹🇼 · Yong Zhao🇺🇸
The pion light-cone distribution amplitude (LCDA) is a central non-perturbative object of interest for the calculation of high-energy exclusive processes in quantum chromodynamics. This article describes the progress in the lattice QCD calculation of the fourth Mellin moment of the pion LCDA using a heavy-quark operator product expansion (HOPE).
↳ hep-lathep-phnucl-thPoS(2023)·2 citations
11
Chiral perturbation theory
Stefan Scherer🇩🇪 · Matthias R. Schindler🇺🇸
Chiral perturbation theory (ChPT) is an effective field theory that describes the properties of strongly-interacting systems at energies far below typical hadron masses. The degrees of freedom are hadrons instead of the underlying quarks and gluons. ChPT is a systematic and model-independent approximation method based on an expansion of amplitudes in terms of light-quark masses and momenta. The following is a brief overview of ChPT that is largely based on Scherer, Schindler, Lect. Notes Phys. 830 (2012), which can be referred to for a more detailed introduction.
↳ hep-phnucl-th2 citations
12
The baryon coupling scheme in an unified SU(3) and SU(6) symmetry formalism
Luiz L. Lopes🇧🇷 · Kauan D. Marquez🇧🇷 · Débora P. Menezes🇧🇷
We calculate the baryon-meson coupling constants for the spin-1/2 baryonic octet and spin-3/2 decuplet in a unified approach relying on symmetry arguments such as the fact that the Yukawa couplings, present in the Lagrangian density of the Walecka-type models, must be an invariant under SU(3) and SU(6) group transformations. The coupling constants of the baryon with the scalar $σ$ meson are fixed to reproduce the known potential depths for the hyperons and $Δ$ resonances, in an approach that can be extended to all particles. We then apply the calculated coupling constants to study neutron star matter with hyperons and deltas admixed to its composition. We conclude that the $Δ^{-}$ is by far the most important exotic particle that can be present in the neutron star interior. It is always present, independent of the chosen parameterization, and might appear in almost every known neutron star, once its onset happens at very low density. Yet, its presence affects the astrophysical properties of the canonical 1.4 M $_{⊙}$ star, and, in some cases, it can even contribute to an increase in the maximum mass reached.
↳ hep-phastro-ph.HEnucl-thPRD(2023)·33 citations

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first authorsco-authorsvia INSPIRE