Nuclear Theory·nucl-th

Friday·March 28, 2025

9 papers—3 primary·6 cross-listed

01
Heavy Neutron Star Phenomenology with an H-dibaryon
Jesper Leong🇦🇺 · Anthony W. Thomas🇦🇺 · Pierre A. M. Guichon🇦🇺
The equation of state for dense nuclear matter in $β$ -equilibrium is explored including the possibility of a doubly-strange H-particle. Consistent with experimental constraints, the mass of the H in free space is taken to be near the $Λ Λ$ threshold. Within the quark-meson coupling model, which we use, no new parameters are required to describe the interaction between the H-dibaryon and the other baryons. The maximum mass is only slightly reduced, and the tidal deformability is essentially unchanged with this addition. In heavy neutron stars the H is abundant and extends as far as 6 km from the center of the core.
nucl-thastro-ph.HEhep-phPRC(2026)·2 citations
02
Are Neutron Stars Rich in H-dibaryons?
Jesper Leong · Anthony W. Thomas · Pierre A. M. Guichon
The possible existence of an H-dibaryon near the $Λ - Λ$ threshold has still not been decided experimentally. This raises the question of the potential effects on neutron stars if it does exist. We explore the consequences within the quark-meson coupling model, using the excluded volume formalism. While the H is abundant in heavy stars the maximum mass is only lowered slightly by its presence.
nucl-thastro-ph.HEhep-phPoS(2025)·1 citation
03
Superfluid density in linear response theory : pulsar glitches from the inner crust of neutron stars
Giorgio Almirante🇫🇷 · Michael Urban🇫🇷
The question of whether there are enough superfluid neutrons in the inner crust of neutron stars to explain pulsar glitches remains a topic of debate. Previous band structure calculations suggest that the entrainment effect significantly reduces the superfluid density. In this letter, a new derivation of the BCS expression for the superfluid density is given. We compute it in the superfluid band theory framework through linear response theory, for a small relative velocity between superfluid and normal components, under the assumption that the pairing gap in the rest frame of the superfluid is constant and not affected by the perturbation. Our result suggests that a formula extensively used in neutron star physics is incomplete. Numerical evaluations for two realistic configurations reveal that the previously neglected contribution drastically alters the picture of the superfluid reservoir in the inner crust of neutron stars, suggesting that about 90% of the neutrons are effectively superfluid.
nucl-thcond-mat.quant-gasPRL(2025)·14 citations
04
Host-dependent frequency offsets in $^{229}$ Th nuclear clockwork
U. C. Perera · H. W. T. Morgan · Eric R. Hudson · Andrei Derevianko
Recent advances in laser excitation of the low-energy nuclear isomer transition in $^{229}$ Th have opened avenues for developing nuclear clocks, a novel quantum technology with exceptional performance and sensitivity to exotic physics. Here we explore the host-dependence of the nuclear clock frequency, focusing on the isomer shift induced by the difference in the nuclear charge distribution between the ground and excited nuclear states. We combine relativistic many-body methods of atomic structure with periodic density functional theory to evaluate the isomer shifts in solid-state hosts. We elucidate the critical importance of the ``relaxation'' effect in evaluating the isomer shifts. Our analysis predicts nuclear clock frequencies for various solid-state and trapped ion platforms: $ω_{clk} (solid state) = 2, 020, 407, 384 (40) MHz$ , $ω_{clk} (^{229} Th^{4 +}) = 2, 020, 407, 648 (70) MHz$ , and $ω_{clk} (^{229} Th^{3 +}) = 2, 020, 407, 114 (70) MHz$ . We also determine the nuclear transition energy for the bare $^{229}$ Th nucleus to be $ω_{nuc} = 8.272 (22) eV$ . Our calculated valence-band isomer shifts for different host materials constrain the nuclear transition frequencies to an 80 MHz-wide frequency window, aiding experimental searches for the $^{229}$ Th nuclear transition in novel materials.
↳ physics.atom-phcond-mat.mtrl-scinucl-thPRL(2025)·11 citations
05
First study of polarized proton-proton scattering with small- $x$ helicity evolution
Daniel Adamiak🇺🇸 · Nicholas Baldonado🇺🇸 · Yuri V. Kovchegov🇺🇸 · Ming Li🇺🇸 · W. Melnitchouk🇺🇸 · Daniel Pitonyak🇺🇸 · Nobuo Sato🇺🇸 · Matthew D. Sievert🇺🇸 · Andrey Tarasov🇺🇸 · Yossathorn Tawabutr🇫🇮
We perform a phenomenological study of helicity-dependent parton distribution functions (PDFs) using small- $x$ helicity evolution equations, incorporating for the first time single-inclusive jet production data in polarized proton-proton ( $pp$ ) scattering at parton momentum fractions $x < 0.1$ . We also simultaneously include double-longitudinal spin asymmetries in inclusive and semi-inclusive deep-inelastic scattering probing $x < 0.1$ . Employing the polarized small- $x$ pure-glue calculation of $pp \to g X$ for the jet production cross section, we modify the large- $N_{c} & N_{f}$ KPS-CTT evolution equations by setting $N_{f} = 0$ to replicate the large- $N_{c}$ (pure-glue) limit, while retaining external quark flavors for the spinor field operators. We find that the $pp$ data have a considerable impact on the helicity PDFs at small $x$ , reducing their uncertainties and leading to a total quark and gluon helicity in the proton for $x < 0.1$ of $- 0.04 \pm 0.23$ . Combining our analysis with the a recent JAM helicity PDF analysis of the world polarized data, which includes $x > 0.1$ , we find a total quark and gluon helicity contribution for $x > 1 0^{- 7}$ of between 0.02 and 0.51.
↳ hep-phhep-exnucl-exnucl-thPRD(2025)·12 citations
06
MPD physics performance studies in Bi+Bi collisions at $s_{N N} = 9.2$ GeV
MPD Collaboration
The Multi-Purpose Detector (MPD) is one of the three experiments of the Nuclotron Ion Collider-fAcility (NICA) complex, which is currently under construction at the Joint Institute for Nuclear Research in Dubna. With collisions of heavy ions in the collider mode, the MPD will cover the energy range 4-11 GeV to scan the high baryon-density region of the QCD phase diagram. With expected statistics of 50-100 million events collected during the first run, MPD will be able to study a number of observables, including measurements of light hadrons and hypernuclei production, particle flow, correlations and fluctuations, have a first look at dielectron production, and modification of vector-meson properties in dense matter. In this paper, we present selected results of the physics feasibility studies for the MPD experiment in Bismuth-Bismuth collisions at an energy of 9.2 GeV, the system considered as one of the first available at the NICA collider.
↳ nucl-exhep-phnucl-thRev.Mex.Fis.(2025)·24 citations
07
Global analysis of fragmentation functions to light neutral hadrons
Jun Gao🇨🇳 · ChongYang Liu🇨🇳 · Mengyang Li🇨🇳 · XiaoMin Shen🇨🇳 · Hongxi Xing🇨🇳 · Yuxiang Zhao🇨🇳 · Yiyu Zhou🇨🇳
Fragmentation functions (FFs) are crucial non-perturbative components in quantum chromodynamics (QCD), playing a vital role in predictions and understanding of the hadronization process. In this paper, we present the FFs for $K_{S}^{0}$ , $η$ , $π^{0}$ mesons, and $Λ$ baryons in the context of global QCD analysis. The data included in the fit are from single inclusive $e^{+} e^{-}$ annihilation (SIA), semi-inclusive deep-inelastic scattering (SIDIS) and proton-proton collisions, with kinematic cuts carefully applied to ensure validity of collinear factorization and perturbative QCD expansion. For the first time, data from SIDIS and hadron-in-jet production in SIA have been incorporated into the extraction of FFs for light-flavor neutral hadrons. Our analysis reveals that these data play a critical role in constraining the gluon distribution, and in distinguishing between different quark flavors. Pulls from different datasets are also studied by performing alternative fits with systematically subtracting groups of data from the nominal fit. For the quality of the fit, good $χ^{2}$ values are achieved for most of the datasets, and FFs are generally well constrained within the momentum fraction region $\pqty 0.1, 0.5$ . The extracted $K_{S}^{0}$ fragmentation functions, together with the $K_{S}^{0}$ FFs constructed from $K^{\pm}$ FFs via isospin symmetry, are used to test isospin symmetry in kaon fragmentation. Although a definitive conclusion cannot be reached yet, these studies have identified several potential measurements that can be performed at existing facilities, which may ultimately help us to arrive at a conclusive answer. With the comprehensive species of FFs extracted within the NPC framework, we are able to perform a test on the momentum sum rule with the light-flavor charged and neutral hadrons.
↳ hep-phhep-exnucl-exnucl-thPRD(2025)·19 citations
08
The impact of future $D$ - and $B$ -meson measurements with the SMOG2 program at LHCb on the determination of nuclear parton distribution functions
Carlo Flore🇮🇹 · Cynthia Hadjidakis🇫🇷 · Daniel Kikoła🇵🇱 · Aleksander Kusina🇵🇱 · Anton Safronov🇵🇱
We perform an analysis of the potential impact of future $D$ - and $B$ -meson measurement within the SMOG2 fixed-target program at the LHCb experiment on nuclear parton distribution functions. Following~\cite{Bursche:2018orf}, we assume that SMOG2 will collect data for five nuclear targets: He, Ne, Ar, Kr, Xe and hydrogen which will provide a baseline for constructing nuclear ratios. The analysis is performed by using the PDF reweighting method. We demonstrate that such a measurement will allow to considerably reduce the current uncertainties of the nuclear gluon distribution and, to some extent, even the uncertainties of the light sea-quark distributions. Furthermore, it will provide the first possibility to systematically study the current assumptions on the $A$ -dependence of the nuclear parton distributions.
↳ hep-phhep-exhep-thnucl-ex+1PLB(2025)·2 citations
09
Internal structure of $T_{cc}$ and $X (3872)$ by using compositeness
Tomona Kinugawa🇯🇵 · Tetsuo Hyodo🇯🇵
The internal structure of the near-threshold exotic hadrons, $T_{cc}$ and $X (3872)$ , are studied by respecting the decay and coupled-channel contributions. The effective field theory model is introduced to calculate the compositeness, the probability of finding the hadronic molecular component. Applying the new interpretation scheme for the complex compositeness of unstable states and using the bare energies of the compact component estimated by the constituent quark model, we find that approximately 50 % of the $T_{cc}$ wavefunction is occupied by the $D^{0} D^{*+}$ molecular component. This indicates that the structure of $T_{cc}$ is primarily dominated by the $D^{0} D^{*+}$ component, having the nearest threshold. However, other components, such as the isospin partner $D^{* 0} D^{+}$ channels, also provide non-negligible contributions. On the other hand, about 90 % of $X (3872)$ is composed of the $D^{0} D ˉ^{0 *}$ molecular component. This is because the non-composite bare state and the charged $D D ˉ^{*}$ threshold are located relatively far from the $X (3872)$ and contribute very little to its internal structure.
↳ hep-phnucl-thPoS(2025)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE