Nuclear Theory·nucl-th

Tuesday·April 7, 2026

16 papers—9 primary·7 cross-listed

01
Phenomenological Criteria of Halo Nuclei in Ne Isotopes via Diffuseness and Helm-Model Approaches with Reaction Cross Sections
Heesung Kwon · Kyoungsu Heo · Seonghyun Kim · Eunja Ha · Myung-Ki Cheoun
We present a systematic study of halo characteristics in the neutron-rich isotopes 28-32Ne within the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc). Microscopic density distributions are analyzed in coordinate space, momentum space, and reaction observables to establish a quantitative and locally defined criterion for halo identification in medium-mass nuclei. The DRHBc densities reveal a pronounced neutron extension in 31Ne. A phenomenological analysis based on deformed Woods-Saxon fits shows a clear isotopic anomaly in the surface diffuseness parameter, with a value of about 1.1 fm for 31Ne, significantly larger than those of neighboring isotopes. The anomalously large diffuseness is therefore treated as the primary phenomenological halo signature, whereas the reduced fitted radius parameter is used only as a supporting consequence of the chosen normalization and tail-sensitive fit. Helm-model form-factor analysis demonstrates that deformation contributes to geometric smearing but does not fully account for the extended spatial structure, as reflected in the enhanced difference between microscopic and folded rms radii. Glauber reaction cross section calculations further confirm a robust relative enhancement of the interaction cross section for 31Ne that persists across reasonable nucleon-nucleon interaction prescriptions. These complementary analyses consistently identify 31Ne as the most prominent halo candidate within the 28-32Ne isotopic chain, while 32Ne exhibits intermediate features and 29Ne shows no clear halo signature. The present framework provides a practical and quantitative approach for identifying halo phenomena in deformed, neutron-rich nuclei beyond the light-mass region.
nucl-th0 citations
02
Anisotropic Flow of light (anti-)(hyper-)nuclei in Pb+Pb Collision at $s_{N N} = 5.36$ TeV
Fu Ma · Zheng-Qing Wang · Xiong-Hong He · Che Ming Ko · Qi-Ye Shou · Kai-Jia Sun · Wenbin Zhao · Wen-Hao Zhou
Using the coalescence model with nucleon phase-space distributions generated by the hybrid MUSIC framework, we study the elliptic flow ( $v_{2}$ ) and triangular flow ( $v_{3}$ ) of (anti-)protons, (anti-)deuterons, (anti-) $^{3} He$ , and $_{Λ}^{3} H$ in Pb+Pb collisions at $s_{N N} = 5.36$ TeV. We find that the simple $v_{2}$ scaling with the number of constituent nucleons $A$ breaks down at high transverse momentum $p_{T} / A > 1.5$ GeV/ $c$ , while an improved scaling relation holds well up to $p_{T} / A \approx 3$ GeV/ $c$ . In contrast, $v_{3}$ exhibits similar behavior under both scaling prescriptions, with no significant difference. We also make predictions for $v_{2}$ and $v_{3}$ of the hypertriton and find these flows are insensitive to the Lambda-deuteron ( $Λ - d$ ) distance inside the hypertriton. Our results are compared with preliminary experimental measurements by the ALICE Collaboration and offer insight into the production mechanisms of light (anti-)(hyper-)nuclei in high-energy heavy-ion collisions.
nucl-thhep-phPLB(2026)·1 citation
03
Heavy and heavy-light tensor and axial-tensor mesons in the Covariant Spectator Theory
Elmar P. Biernat🇵🇹 · Alfred Stadler🇵🇹
We present the first calculation of tensor and axial-tensor mesons with total spin $J \geq 2$ within the Covariant Spectator Theory. We employ a refined quark-antiquark interaction kernel that incorporates the momentum dependence of the strong coupling, replacing the previously used constant term of the kernel. Global least-squares fits to the masses of experimentally established heavy and heavy-light meson states yield an excellent description of the mass spectrum for $J^{P} = 0^{\pm}, 1^{\pm}, 2^{\pm}$ , and $3^{\pm}$ using only eight adjustable parameters.
nucl-thhep-phActa Phys.Polon.Supp.(2026)·0 citations
04
Disentangling Flow Contributions from the Chiral Magnetic Effect in U+U Collisions with Forward-Backward Multiplicity Asymmetry
Kaiser Shafi🇮🇳 · Sandeep Chatterjee🇮🇳
The observation of the Chiral Magnetic Effect (CME) in heavy-ion collisions remains challenging because of large flow-induced backgrounds and experimental constraints. We demonstrate that the forward-backward multiplicity asymmetry (FBMA) provides a robust and experimentally accessible control parameter to separate the flow background from CME signal in the collisions of deformed nuclei, such as prolate uranium where FBMA is naturally enhanced and correlated with the initial-state geometry. Monte Carlo Glauber simulations indicate that varying FBMA within a fixed centrality class modulates ellipticity largely independently of the magnetic-field correlator, establishing FBMA as a practical tool for disentangling CME signals from flow driven background.
nucl-thhep-phhep-th0 citations
05
Nonlocality Effect in the Alpha decay half-lives of superheavy nuclei with XGBRegressor
Jinyu Hu · Chen Wu
Building on the work of E. L. Medeiros [1] and our previous study [2], we generalize the alpha-nucleus nonlocality effect to odd-A and odd-odd nuclei within the two-potential approach (TPA) framework. The coordinate-dependent parameters introduced by this nonlocality are optimized using an advanced gradient boosting regression model. This improved TPA is applied to calculate the $α$ -decay half-lives of 599 nuclei with $Z = 52 - 118$ , yielding a root-mean-square (RMS) deviation that is 74.8 $%$ lower than that of the original TPA. Subsequently, we employ the improved TPA, along with the DZR [3] and MUDL [4]models, to predict alpha-decay half-lives for 142 superheavy nuclei with $Z = 117 - 120$ . The predictions from all three models are in close agreement, with the results from our improved TPA and the DZR model being nearly identical.
nucl-th0 citations
06
Generation of fission yield covariance matrices and its application in uncertainty analysis of decay heat
Wendi Chen · Tao Ye · Hairui Guo · Jiahao Chen · Bo Yang · Yangjun Ying
The uncertainties and covariance matrices of fission yield are important in the uncertainty analysis of decay heat. At present, there are no covariance matrixes of fission yield given in the evaluated nuclear data library, although they have provided the uncertainties with good estimates. In this work, the generalized least squares (GLS) updating approach was adopted to evaluate the fission yield covariances with the constraints from basic physical conservation equation and chain yield data, using the nuclear data files from ENDF/B-VIII.0, JENDL-5 and JEFF-3.3. Based on these original and updated data, summation calculation was performed for fission pulse decay heat of thermal neutron-induced fission of $^{235}$ U. The uncertainties of decay heat were obtained through generalized perturbation theory, including the uncertainties propagated from fission yield, decay energy, decay constant and branching ratio. The original uncorrelated yield data contributes a $\sim 4%$ uncertainty at all times and dominates the decay heat uncertainty at cooling times longer than \SI{100}{s}. With the generated covariance matrixes, the uncertainty of calculated decay heat is strongly reduced and decay energy data makes a major contribution in general. The relative uncertainties at cooling time \SI{0.1}{\second} are $\sim$ 10 $%$ for ENDF/V-VIII.0 and JEFF-3.3 and $\sim$ 5 $%$ for JENDL-5 and those at cooling time 10 $^{5}$ s are about 1 $%$ for three libraries. The influence of the GLS updating procedure on the contributions of important fission products to decay heat and their sensitive coefficients was also discussed.
nucl-thNucl.Sci.Tech.(2026)·0 citations
07
Dissipative spin hydrodynamics in Bjorken flow and thermal dilepton production
Sejal Singh🇮🇳 · Sourav Dey🇮🇳 · Arpan Das🇮🇳 · Hiranmaya Mishra🇮🇳 · Amaresh Jaiswal🇮🇳
We investigate the boost-invariant expansion of a recently developed first-order spin hydrodynamic framework in which the spin chemical potential is treated as a leading-order hydrodynamic variable. Considering a symmetric energy-momentum tensor and a separately conserved spin tensor, we derive the coupled evolution equations for the medium temperature and the independent components of the spin chemical potential in the presence of both viscous and spin-diffusive transport coefficients. For a boost-invariant system, only the magnetic-like components of the spin chemical potential survive, and their evolution is shown to depend sensitively on the spin transport coefficients. The transverse spin components decay more rapidly due to spin dissipation, while the longitudinal component survives for a longer duration. We further demonstrate that the evolution of the spin degrees of freedom modifies the temperature profile of the expanding medium. Using the resulting temperature profiles, we calculate thermal dilepton production rates from quark-antiquark annihilation. We find that the presence of spin dynamics enhances the dilepton yield relative to standard dissipative hydrodynamics, with the magnitude of the enhancement depending on the spin transport coefficients. Our results indicate that thermal dileptons can provide an indirect probe of spin dynamics and spin transport in the quark-gluon plasma.
nucl-thhep-ph2 citations
08
Rigid triaxiality has the SU(3) symmetry: $^{166}$ Er as an example
Chunxiao Zhou · Xue Shang · Tao Wang
The emergence of triaxiality in the low-lying collective bands of $^{166}$ Er is systematically explored within the SU3-IBM. In this framework, SU(3) higher-order interactions are included, which enable the descriptions of various quadrupole deformations. The triaxiality of $^{166}$ Er is described with a triaxiality angle $γ = 9. 7^{\circ}$ . In addition, the calculated energy spectra, $B (E 2)$ transition strengths, and quadrupole moments show excellent agreement with experimental data. These results provide further evidence supporting the SU(3) triaxial interpretation of $^{166}$ Er and confirm its triaxial deformation rather than the prolate shape.
nucl-th0 citations
09
The Ground State Aspects and the Impact of Shell Structures on the Stability of Es-Isotopes
C. Dash · A. Anupam · I. Naik · B. K. Sharma · B. B. Sahu
In this work, we have analyzed the nuclear structure and several prospective decay characteristics of the $^{240 - 259}$ Es $_{99}$ isotopes. For this we use Relativistic Mean Field model (RMF) with NL-SH and NL3* force parameter in an axially deformed oscillator basis. In structural properties, we have analyzed binding energy (B.E.), skin thickness ( $r_{n p}$ ) , charge radius ( $r_{c}$ ), one neutron separation energy ( $S_{1 n}$ ), two neutron separation energy ( $S_{2 n}$ ), differential variation of two neutron separation energy ( $d S_{2 n}$ ), the single particle energy and its variation with quadrupole deformation parameter of Es isotopes. We have also estimated the $α$ -decay, $β$ -decay and cluster decay half lives of Es isotopes to analyze the shell structure and also to predict the suitable decay mode among them. The $α$ -decay half-life periods are calculated using the MUDL and AKRE formulae using both our calculated Q-values and empirically assessable Q-values. In a similar manner, we have computed the half-lives of cluster decay using Universal Decay Law and HOROI formula. A longer decay half-life indicates a shell stabilized parent nucleus, while a small parent half-life suggests the shell stability of the daughter. This study provides us the insights regarding the structural changes with the change in neutron number enabling us to predict shell closures and nuclear stability. We found a shell/sub-shell closure at N = 154 for the NL-SH parameter set. This research aids in our comprehension of Es isotopes' shell structure and decay mechanism.
nucl-thphysics.soc-phPhys.Scripta(2026)·1 citation
10
Precise determination of electron-capture $Q$ value of $^{113}$ Sn decay related to electron neutrino mass measurements
Zhuang Ge🇫🇮 · Tommi Eronen🇫🇮 · Vasile Alin Sevestrean🇷🇴 · Ovidiu Nitescu🇷🇴 · Sabin Stoica🇷🇴 · Marlom Ramalho🇫🇮 · Jouni Suhonen🇫🇮 · Anu Kankainen🇫🇮 · Marjut Hukkanen🇫🇮 · Arthur Jaries🇫🇮 · Ari Jokinen🇫🇮 · Joel Kostensalo🇫🇮 and 6 other authors
A high-precision measurement of the electron-capture (EC) decay $Q$ value for the ground-state-to-ground-state (gs-to-gs) transition of $^{113}$ Sn to $^{113}$ In has been performed using the JYFLTRAP double Penning trap mass spectrometer. Employing the phase-imaging ion-cyclotron-resonance technique, the isomeric state of $^{113}$ Sn at 77.389(19) keV was resolved, and the cyclotron frequency ratio measured between the isomer $^{113 m}$ Sn and the daughter nucleus $^{113}$ In. This yielded an isomer-to-ground-state $Q$ value of 1116.64(19) keV and gs-to-gs $Q$ value of 1039.25(19) keV. The atomic mass excess of $^{113}$ Sn was determined as $-$ 88327.87(27) keV/c $^{2}$ , in excellent agreement with the Atomic Mass Evaluation 2020 (AME2020) but with a sixfold precision improvement. Using nuclear energy-level data for $^{113}$ In, we identified two low $Q$ -value transitions of the ground state of $^{113}$ Sn to excited states of $^{113}$ In at 1024.280(50) keV ( $Q_{E C}^{*} = 14.97 (20)$ keV, second forbidden non-unique) and 1029.650(50) keV ( $Q_{E C}^{*} = 9.60 (20)$ keV, allowed). The allowed transition exhibits small energy differences ( $Δ_{L 1} = 5.58 (20)$ keV, $Δ_{L 2} = 5.87 (20)$ keV) from L1 and L2 shell binding energies, enhancing endpoint events. Partial half-lives and energy-release spectra were calculated using the self-consistent Dirac-Hartree-Fock-Slater (DHFS) method (including exchange, overlap, shake-up, and shake-off corrections) together with the nuclear shell model, show enhanced endpoint sensitivity for the allowed transition to the state at 1029.650 keV. Including subthreshold atomic states in the spectral function enhances the EC rate near the zero-neutrino-momentum region by a factor of five, enabling new approaches for low $Q$ -value EC reactions in neutrino-mass studies.
↳ nucl-exnucl-th0 citations
11
Two Lectures on the Phase Diagram of QCD
Larry McLerran🇺🇸
The phase diagram of QCD at finite temperature and density is discussed. Large numbers of quark colors, $N_{c} >> 1$ , is used to explain generic features of the phase diagram. For temperatures below $T \leq 160$ ~MeV at zero baryon number density, the three dimensional string model is shown to describe the thermodynamics of QCD, and as well, the integrated spectrum of non-Goldstone mesons and glueballs. The lowest mass state in the spectrum of the open and closed string is treated separately due to the tachyon problem of string theory. This is with no undetermined free parameters. It is argued that there are at least three phases at zero baryon number density characterized by the $N_{c}$ dependence of extensive thermodynamic quantities. It is also argued that the intermediate phase has restored chiral symmetry. At high baryon number density and low temperature, again there are three phases. A Quarkyonic phase, with energy density of order $N_{c}$ , is distinguished from its counterpart at low baryon density and temperature by its chiral properties.
↳ hep-phhep-thnucl-thActa Phys.Polon.B(2026)·3 citations
12
Causality, the Kovtun-Son-Starinets bound, and a novel sum rule for spectral densities
G. Yu. Prokhorov🇷🇺 · O. V. Teryaev🇷🇺
We directly show that the local ratio of the shear viscosity to the entropy density for Unruh radiation at a finite distance from the horizon is universal and satisfies the relation $η / s = 1/ (4 π c_{s}^{2})$ , which involves the speed of sound $c_{s}$ . Since $c_{s}^{2} \leq 1$ by causality, this establishes the close connection between the famous Kovtun-Son-Starinets bound and causality. Moreover, we show that the ratio of bulk to shear viscosity saturates another well-known bound for the bulk viscosity, predicted within holographic approach. We also show that the condition of isotropy of thermal radiation in the Rindler space leads to a novel sum rule relating the $c^{(0)} (μ)$ and $c^{(2)} (μ)$ spectral densities, and we explicitly demonstrate its validity for conformal field theory and free massive Dirac fields in any number of dimensions. The sum rule provides the validity of Pascal law and bears some similarity with Burkhardt-Cottingham sum rule for spin-dependent parton distributions. Our result suggests a new perspective on dissipative transport phenomena in media undergoing extreme acceleration, such as quark-gluon plasma created in relativistic heavy-ion collisions.
↳ hep-thhep-phnucl-th1 citation
13
Lattice studies of chimera baryons in Sp(4) gauge theory
Jong-Wan Lee🇰🇷 · Ed Bennett🇬🇧 · Luigi Del Debbio🇬🇧 · Niccolò Forzano🇬🇧 · Ryan C. Hill🇬🇧 · Deog Ki Hong🇰🇷 · Ho Hsiao🇯🇵 · C.-J. David Lin🇹🇼 · Biagio Lucini🇬🇧 · Alessandro Lupo🇫🇷 · Maurizio Piai🇬🇧 · Davide Vadacchino🇬🇧 · Fabian Zierler🇬🇧
We study chimera baryons, fermion bound states composed of two (hyper)quarks transforming in the fundamental and one in the antisymmetric representation of a non-Abelian gauge group. While in QCD they coincide with ordinary baryons, in composite Higgs models (CHMs) with top partial compositeness, spin-1/2 chimera baryons serve as partners of the top quark and are responsible for its large mass. We perform non-perturbative lattice calculations of the low-lying spectrum of the chimera baryons, in a specific realization of CHMs based on a Sp(4) gauge theory. In the quenched approximation, we present the numerical results in the continuum and massless limits. Then, for dynamical fermions, we measure the spectrum and matrix elements by employing a newly developed spectral density analysis for several choices of the lattice parameters.
↳ hep-lathep-phnucl-thJ.Subatomic Part.Cosmol.(2026)·1 citation
14
Neural-network quantum states for solving few-body problems: application to Efimov physics
Sora Yokoi · Shimpei Endo · Hiroki Saito
Neural-network quantum states have recently emerged as a powerful method for solving quantum many-body problems, with notable successes in lattice systems. Here, we extend this approach to strongly interacting few-body problems in continuous space, and demonstrate its capability by computing the Efimov states and associated few-body bound states. Using a fully connected feedforward neural network with Jacobi coordinates as inputs, combined with a projection method, we compute the ground and first excited states for three- to six-body systems of identical bosons at unitarity, as well as a mass-imbalanced fermionic system consisting of two identical fermions and a third particle. The obtained energies of the ground and first excited states agree well with previously reported results. Furthermore, the proposed approach also reproduces key features of Efimov states, including the discrete scale invariance, the characteristic geometric structure of the wave function, and the critical-mass behavior in mass-imbalanced fermionic systems. Our method can be readily applied to a broad class of strongly correlated few-body problems in continuous space.
↳ cond-mat.quant-gasnucl-thphysics.chem-phphysics.comp-ph1 citation
15
Neutron star with dark matter using vector portal
Deepak Kumar (IISER Berhampur)🇮🇳 · Ranjita K. Mohapatra (Rajdhani College)🇮🇳 · Hiranmaya Mishra (IOP & NISER)🇮🇳 · Sudhanwa Patra (IIT Bhilai & IOP)🇮🇳
Compact astrophysical objects, such as neutron star, can provide a unique environment where the interplay between strongly interacting nuclear matter and dark matter (DM) can yield possible observable signatures. We investigate here the impact of fermionic DM interacting with nucleons via a vector mediator ( $Z^{'}$ ) portal inside neutron stars using the relativistic mean-field (RMF) framework. Unlike scalar portal DM models, which primarily modify the effective nucleon mass through scalar interactions, vector mediators (Z') introduce additional repulsive interactions that directly affect the baryonic chemical potential and the pressure of dense matter. We show that the precise measurements of neutron star properties, including the mass-radius relation and tidal deformability from gravitational wave observations, X-ray and radio observations of pulsars, can shed light on properties of DM. We study the gross structural properties of a neutron star using the Tolman-Oppenheimer-Volkoff (TOV) equations, employing an equation of state (EOS) for neutron star matter in the presence of vector portal-assisted DM. The resulting stellar configurations consistent with observational bounds from gravitational wave observations (GW170817) in LIGO/Virgo and X-ray observations of pulsar PSR J0030+0451 in NICER, are shown to constrain the vector portal DM parameters. It is observed that, while large portal mass can soften the EOS of the DM admixed neutron star matter, the light portal mass can make the EOS stiffer at large densities resulting in distinct mass-radius relation and the tidal deformability between the two scenarios. The vector portal DM scenario, with DM interaction with quarks via Z' vector boson, can establish a direct connection to terrestrial searches, including direct and indirect detection and collider searches for the Z' boson.
↳ hep-phnucl-thPRD(2026)·2 citations
16
Glueballs, Constituent Gluons and Instantons
Edward Shuryak🇺🇸 · Ismail Zahed🇺🇸
We present a constituent two-gluon description of the lowest-lying glueball states in pure Yang--Mills theory, calibrated against quenched lattice results. The framework incorporates an instanton-induced dynamical gluon mass, Casimir-scaled adjoint confinement, the short-distance adjoint Coulomb interaction, and instanton-induced central and tensor forces. The scalar $0^{++}$ glueball is found to be exceptionally compact, with a radius of order the instanton size, $ρ \sim \frac{1}{3} fm$ , consistent with lattice indications. By contrast, the tensor $2^{++}$ state remains spatially extended due to the centrifugal barrier. We also discuss the role of $S$ - $D$ mixing. A semiclassical analysis further supports Regge behavior for excited states, in agreement with lattice results.
↳ hep-phhep-lathep-thnucl-th1 citation

Affiliations

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