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Nuclear Theory·nucl-th

Tuesday·April 7, 2026

16 papers—9 primary·7 cross-listed

All16Primary9Cross-lists7
  1. 10

    Precise determination of electron-capture value of 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 value for the ground-state-to-ground-state (gs-to-gs) transition of Sn to In has been performed using the JYFLTRAP double Penning trap mass spectrometer. Employing the phase-imaging ion-cyclotron-resonance technique, the isomeric state of Sn at 77.389(19) keV was resolved, and the cyclotron frequency ratio measured between the isomer Sn and the daughter nucleus In. This yielded an isomer-to-ground-state value of 1116.64(19) keV and gs-to-gs value of 1039.25(19) keV. The atomic mass excess of Sn was determined as 88327.87(27) keV/c, in excellent agreement with the Atomic Mass Evaluation 2020 (AME2020) but with a sixfold precision improvement. Using nuclear energy-level data for In, we identified two low -value transitions of the ground state of Sn to excited states of In at 1024.280(50) keV ( keV, second forbidden non-unique) and 1029.650(50) keV ( keV, allowed). The allowed transition exhibits small energy differences ( keV, 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 -value EC reactions in neutrino-mass studies.

    ↳ nucl-exnucl-th0 citations
  2. 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, , is used to explain generic features of the phase diagram. For temperatures below ~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 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 , 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
  3. 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 , which involves the speed of sound . Since 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 and 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
  4. 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
  5. 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
  6. 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 () 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
  7. 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 glueball is found to be exceptionally compact, with a radius of order the instanton size, , consistent with lattice indications. By contrast, the tensor state remains spatially extended due to the centrifugal barrier. We also discuss the role of - mixing. A semiclassical analysis further supports Regge behavior for excited states, in agreement with lattice results.

    ↳ hep-phhep-lathep-thnucl-th1 citation

Affiliations

first authorsco-authorsvia INSPIRE