PaperPanorama

Nuclear Theory·nucl-th

Thu·Oct 8, 2026

7 papers—1 primary·6 cross-listed

All7Primary1Cross-lists6
  1. 01

    Novel chiral-wobbling excitation mode in atomic nuclei

    Kouser Qureshie · S. P. Rouoof · J. A. Sheikh · Nazira Nazir · G. H. Bhat · S. Jehangir · N. A. Rather · R. J. Guo · S. Y. Wang · C. Liu · Q. B. Chen · S. Frauendorf

    The properties of high-spin band structures in Br nucleus are investigated using the triaxial projected shell model (TPSM) and particle triaxial rotor (PTR) approaches. It has already been demonstrated that lowest three bands observed in Br have a characteristic feature of a chiral-wobbler. The first excited band is the chiral partner of the yrast band and the second excited band is the wobbling band based on the yrast state. We have analyzed the third excited band using the TPSM and PTR calculated quantities, and a unique character of this band is revealed. It is predicted that this band is the chiral partner of the second excited band, and is also a wobbling mode based on the first excited band.

    nucl-thnucl-ex
  2. 02

    Axion effects on hybrid stars: earlier hadron-quark phase transition and larger quark-matter cores

    Yu-Heng Liu · He Liu · Hong-Ming Liu · Min Ju · Xu-Hao Wu · Peng-Cheng Chu

    We investigate the effects of axions on the properties of hybrid stars and the possible hadron-quark phase transition in their cores within the Maxwell construction. The hadronic phase is described by the improved isospin- and momentum-dependent interaction (ImMDI) model, while the quark phase is modeled by a three-flavor Nambu--Jona-Lasinio (NJL) model with an axion-modified Kobayashi-Maskawa-'t Hooft (KMT) interaction. Based on the obtained equation of state, we analyze the properties of hybrid-star matter, including the speed of sound and the polytropic index, as well as the structural characteristics of hybrid stars, including the mass-radius relation and the properties of the quark core. Our study shows that the axion field slightly stiffens the equation of state of quark matter but significantly shifts the hadron-quark phase transition to lower baryon densities. These two effects compete in influencing the equation of state of hybrid-star matter, and may even soften it, which is different from the effect of the vector coupling interaction. Consequently, the axion field has only a weak influence on the maximum mass of hybrid stars, but significantly increases the mass and radius of the quark core, especially for weak vector coupling. These results indicate that, within the present Maxwell construction, the primary role of the axion is to promote an earlier hadron-quark transition at low densities and to enlarge the quark core.

    ↳ astro-ph.HEnucl-th
  3. 03

    Tensor-structure sum rules for spin-1 targets at all

    Vladimir Pascalutsa · Marc Vanderhaeghen

    We derive a family of sum rules for the tensor structure functions of targets with spin one or higher, rooted in exact Siegert relations. The mixed rank-two -- degeneracy combines amplitudes of opposite crossing parity and, under the superconvergence assumption, gives in the Hoodbhoy--Jaffe--Manohar (HJM) basis. At large , the protected moment agrees with Detmold's target-mass-complete twist-two OPE; in the strict Bjorken projection, and if is neglected, it reduces to the Efremov--Teryaev (ET)-type condition , whose measured-range footprint is consistent with the HERMES data. Two further rank-two combinations connect crossing-even amplitudes and determine the corresponding subtraction functions through weighted HJM moments. The protected combination can be isolated through separated tensor and responses, providing a direct experimental strategy for JLab and, ultimately, a future EIC.

    ↳ hep-phhep-thnucl-exnucl-th+1
  4. 04

    Bjorken sum rule down to the elastic region from the lattice

    J. A. Crawford · A. Hannaford-Gunn · R. Horsley · P. E. L. Rakow · T. G. Schar · G. Schierholz · H. Stüben · R. D. Young · J. M. Zanotti

    We present a lattice determination of the Bjorken sum rule via a Feynman-Hellmann calculation of the polarised forward Compton amplitude. We evaluate the lowest moment of the nucleon's polarised structure function, , which we calculate over the range GeV, covering both non-perturbative and perturbative regions. We compare our calculated moments with the Bjorken sum rule, and discuss implications for the calculation of higher-twist effects, as well as evaluations of from hadronic quantities to complement phenomenological and other lattice methods.

    ↳ hep-lathep-phnucl-th
  5. 05

    Composition -modes and -modes of neutron stars with gravitationally coupled dark matter: degeneracy with the symmetry energy

    Probit J Kalita · Bharat Kumar · H C Das

    Composition gravity () modes have been proposed as a probe of dark matter in neutron stars, on the basis of one-fluid models in which the dark matter is in chemical equilibrium with the neutrons. We computed in full general relativity the - and -modes of stars in which fermionic dark matter couples to the nucleons only through gravity, and inferred the dark mass fraction from NICER and GW170817 data with a prior that comprises nucleonic equations of state (EOSs) from Skyrme and relativistic mean-field functionals, among them the models of Dutra \textit{et al.} and of the compilation of Sun, Bhattiprolu and Lattimer. The data do not prefer dark matter and bound its mass fraction at () for particle masses of --~GeV. Coupled only through gravity, the dark matter reaches the buoyancy that restores a -mode only through the gravitational field: a dark core holding of the mass raises the fundamental -mode by at fixed EOS, several times less than in the one-fluid picture. The larger effect is indirect: a star with a dark core needs a stiffer nucleonic EOS, and since the -mode is set by the density dependence of the symmetry energy, its frequency reflects the EOS that the star requires rather than the dark matter it contains; at fixed radius and symmetry energy a core holding of the mass is equivalent to a change of the slope of ~MeV. The -mode, which follows the mean density, behaves differently: a dark core breaks the relation between the -mode and the tidal deformability by about one percent, far outside the posterior spread of nucleonic stars.

    ↳ astro-ph.HEgr-qcnucl-th
  6. 06

    Two-pion exchange potential in system

    Daiki Suenaga · Masayasu Harada

    Motivated by the recent HAL QCD lattice results on the - potential at nearly physical point MeV, we theoretically examine effects from the two-pion exchange in (semi-)long-range parts of the system. We employ the framework of heavy-meson chiral perturbation theory with heavy-quark spin symmetry. The pion exchanges up to next-to-next-to-leading order (NLO) are taken into account. In order to separate the (semi-)long-range contributions, we apply the dispersion-relation method to one-loop diagrams. As a result, we find that the lattice data on the - potential in the regime of is reproduced by adjusting the unknown couplings. In particular, it turns out that contributions from isospin-independent NLO triangle diagrams play a central role in reproducing the lattice data of the form in . We also present predictions of other - potentials, where the similar two-pion exchange tail is predicted. Our findings provide useful information on the (semi-)long-range regime of the - potential focusing on two-pion exchanges.

    ↳ hep-phhep-latnucl-th
  7. 07

    An effective macroscopic description of early-stage chemical equilibration in high-energy heavy-ion collisions

    Anar Akbarov · Hendrik Roch · Chun Shen

    The early stage of high-energy heavy-ion collisions undergoes transient dynamics, evolving non-perturbatively from a gluon-rich to a chemically equilibrated quark-gluon plasma. We develop an effective hydrodynamic approach that casts the microscopic quark equilibration dynamics as the relaxation evolution of an effective macroscopic bulk viscous pressure. The evolution of this effective bulk viscous pressure captures quark chemical equilibration and the breaking of conformal symmetry, thereby providing a smooth onset of the lattice QCD equation of state after a few fm/ in the hydrodynamic evolution. We investigate phenomenological effects of this macroscopic description on final-state observables in , , and collisions at the Large Hadron Collider.

    ↳ hep-phnucl-th