Nuclear Theory·nucl-th

Tuesday·May 26, 2026

13 papers—5 primary·8 cross-listed

06
Solar Axions from Nuclear Transitions
Tanmoy Kumar🇮🇳 · Newton Nath🇮🇳
We investigate the possibility of detecting 14.4 keV and 9.4 keV solar axions and axion-like particles that could be produced in the M1 nuclear transitions of $^{57}$ Fe and $^{83}$ Kr, respectively. To do so, we used data from soft X-ray observations of the quiet Sun collected by the Solar X-ray Monitor (XSM) on board India's Chandrayaan-2 lunar mission. We observe that although the effective axion-nucleon couplings for $^{83}$ Kr and $^{57}$ Fe differ only slightly, their fluxes differ by nearly three orders of magnitude. Consequently, the limit on $∣ g_{a N}^{eff} \times g_{aγ γ} ∣$ and only $g_{aγ γ}$ vs. $m_{a}$ provide more than an order-of-magnitude stronger constraint for Fe than for Kr.
↳ hep-phastro-ph.HEastro-ph.SRnucl-th0 citations
07
Low-lying $Λ$ and $Σ$ resonances studied with the forward $K^{*}$ productions off the proton induced by a high-momentum $π$ beam
H. Kamano🇯🇵 · T.-S. H. Lee🇺🇸
We develop a novel model utilizing the forward $K^{*}$ production reaction off the nucleon, $π N \to K^{*} M B$ , induced by a high-momentum $π$ beam, as a tool to study low-lying $Y^{*}$ resonances below and just above the $K ˉ N$ threshold. Because conventional $K^{-} p$ scattering experiments face difficulties in directly accessing this kinematic region, the proposed reaction offers a valuable complementary approach for $Y^{*}$ spectroscopy. The constructed model is based on the one-meson exchange mechanism, which is known to dominate forward-angle production at high energies, and the half-off-shell scattering amplitudes from the ANL-Osaka dynamical coupled-channels models (Model A and Model B). We predict various observables, including differential cross sections and angular distributions. Our results demonstrate significant enhancements in the subthreshold region of the invariant mass spectra. Notably, we show that overlapping resonances, such as a potential new $3/ 2^{+}$ $Σ$ state and the well-established $Σ (1385) 3/ 2^{+}$ , can constitute a single peak in the $π Λ$ mass spectrum, indicating that the existence of previously unconfirmed subthreshold states cannot be ruled out by analyzing only the existing mass spectrum data. Furthermore, we find that angular distributions provide strong discriminatory power to disentangle such overlapping states through partial-wave interference effects, while the $t^{'}$ and $ϕ_{M}^{*}$ dependencies provide crucial constraints on the high-energy production mechanisms. Our predictions for these highly sensitive observables can facilitate high-statistics measurements, which are accessible at modern hadron facilities such as J-PARC, to unravel the $S = - 1$ $Y^{*}$ mass spectrum.
↳ hep-phhep-exnucl-exnucl-thPRC(2026)·0 citations
08
The Pseudospectral Method for the Dirac Equation with Confining Potential
Dengshan Liu · Huihui Xie · Pengxiang Du · Jian Li · Tomoya Naito
We observe that solving the Dirac equation for confined potentials using the generalized pseudospectral (GPS) method leads to deteriorating convergence of energy eigenvalues and highly oscillatory in wave functions as the confinement radius decreases. It is found that this issue stems from the first-order differentiation formulation employed in GPS method. Motivated by this insight, we adopt the kinetically balanced generalized pseudospectral method, which incorporates the kinetically-balanced condition into the GPS method. Numerical results demonstrate that the mono-kinetically-balanced generalized pseu dospectral (MKB-GPS) method yields converged energy eigenvalues and generates smooth, continuous wave functions. This is the first application of the MKB-GPS method to confined potentials, and its effectiveness is validated for small confinement radii.
↳ physics.atom-phmath-phmath.MPnucl-th+10 citations
09
Superfluid fraction and effective ion mass in the crystalline crust of a neutron star: role of interband response
Nicolas Chamel
Neutron superfluidity in the inner crust of a neutron star is further investigated, focusing on the role of the interband response in the superfluid fraction and the effective mass of crustal ions induced by their motion through the superfluid. Calculations are performed within the linear response theory of the self-consistent time-dependent Hartree-Fock-Bogoliubov equations with Skyrme nuclear energy density functionals in the Bardeen-Cooper-Schrieffer approximation. The absence of interband response in previous analyses is clarified. The neutron superfluid density is formally shown to be consistent with the entrainment matrix derived earlier in homogeneous neutron-proton superfluid mixture, thus providing a unified description of entrainment effects in the inner crust and outer core of a neutron star within the same microscopic framework. The relative importance of the intraband and interband responses in different regions of the crust is numerically assessed from three-dimensional band-structure calculations, taking into account quantum zero-point motion of ions about their equilibrium position. The neutron superfluid fraction is found to be enhanced by the interband response, resulting in effective ion masses that remain close to the mass of quantum mechanically bound nucleons for realistic neutron pairing gaps. Results are compared to predictions from classical hydrodynamics with different prescriptions for the permeability of ions to superfluidity.
↳ astro-ph.HEcond-mat.supr-connucl-th0 citations
10
Odderon Form Factors in Reggeized Spin-2 Pomeron and Spin-3 Odderon Exchange in $pp$ and $p p ˉ$ Elastic Scattering
Dominador F. Vaso · Jr. · Prin Sawasdipol · Jingle B. Magallanes · Chakrit Pongkitivanichkul · Daris Samart
We investigate the form-factor dependence of Reggeized tensor Pomeron and Odderon exchanges in high-energy elastic $pp$ and $p p ˉ$ scattering. The spin structure is implemented through explicit covariant spin-2 and spin-3 projectors, kept factorized from the Reggeized scalar kernels, so that vertex effects can be separated from trajectory dynamics. Seven Odderon--proton form-factor parametrizations are tested against a global dataset including TOTEM $pp$ data at $s = 2.76$ , $7$ , $8$ , and $13$ ~TeV and Tevatron $p p ˉ$ data at $s = 1.80$ and $1.96$ ~TeV. A clear hierarchy is found. Six dipole, polynomial, Gaussian, and hybrid parametrizations give comparable fit qualities, $χ_{red}^{2} ≃ 1.44$ -- $1.48$ , whereas a one-parameter exponential form, $F_{O} (t) = exp [- B ∣ t ∣/2]$ , yields $χ_{red}^{2} = 0.98$ for 138 degrees of freedom. The fitted couplings and Regge slopes remain comparatively stable across the form-factor choices, indicating that the improvement is driven mainly by the Odderon--proton vertex rather than by large compensating shifts in trajectory parameters. The exponential form admits an impact-parameter interpretation as a Gaussian transverse profile, with an effective radius $⟨ b^{2} ⟩ = 2 B ℏ c$ . The extracted radii are of hadronic size and suggest a peripheral soft Odderon interaction. The shrinking $t$ -range over which the single-Regge-exchange description remains accurate at increasing energy indicates the onset of absorptive and unitarity corrections. These results provide a compact phenomenological framework for connecting the $pp / p p ˉ$ dip--bump difference with the transverse structure of $C$ -odd color-singlet exchange.
↳ hep-phhep-thnucl-th1 citation
11
Intermittency and fractal behaviour of charged particles in EPOS4 and PYTHIA8 generated events at LHC energies
Fakhar Ul Haider🇮🇳 · Ramni Gupta🇮🇳 · Salman Khurshid Malik🇮🇳 · Balwan Singh🇮🇳 · Zarina Banoo🇮🇳 · Pryianka Choudhary
Large number density fluctuations of the charged particles produced in heavy-ion collisions are a promising signature for exploring the QCD phase transition and critical point in the nuclear matter phase diagram. Intermittency methodology is used to probe the fractal and scale invariant nature of these fluctuations. Intermittency is the phenomenon of power-law growth of the normalized factorial moments ( $F_{q}$ ) of the number density distributions over decreasing bin size. The charged particles generated in the midrapidity region using PYTHIA8 and EPOS4 (UrQMD ON/OFF) for Pb--Pb collisions at $s_{NN}$ = 5.02 TeV are studied. Scaling behaviour of $F_{q}$ are studied as a function of phase space partitioning and second order moments to quantify the particle production nature within the default constraints of the two models. The scaling exponent related to the phase transition and parameters connected to fractal nature obtained for both these models show the absence of fluctuations of critical nature and multifractal behaviour.
↳ hep-exhep-phnucl-th0 citations
12
Core-collapse supernovae and supernova neutrinos
B. Mueller🇦🇺 · B. Sykes🇦🇺
Core-collapse supernovae are the terminal explosions of massive stars. After successive phases of nuclear fusion proceeding up to silicon burning, these stars form an iron core that is supported by electron degeneracy pressure. The core eventually collapses to a proto-neutron star, and in most cases the outer layers of the star are ejected by a shock wave, with a kinetic energy of order $1 0^{51} erg$ . Neutrinos and multi-dimensional fluid flow play a key role in extracting energy from the collapsed core to drive the explosion. After adumbrating the astrophysical context of stellar evolution and transient observations, this chapter sketches the modern theory of neutrino-driven supernova explosions, and discusses the key role of nuclear physics and neutrino interaction rates in the supernova problem. It also outlines the role of neutrinos and gravitational waves as probes into the supernova core.
↳ astro-ph.HEgr-qchep-phnucl-th2 citations
13
Predicted Exotic Doubly Heavy-Strange Pentaquarks
Albert Feijoo🇪🇸 · Eulogio Oset🇪🇸
We predict exotic doubly heavy--strange pentaquarks with minimal quark content $u d ˉ s Q Q^{'}$ ( $Q Q^{'} = cc, b c, bb$ ) within a coupled-channel unitary framework where the interaction is derived from an extension of the local hidden gauge approach to the heavy-quark sector. We obtain a robust spectrum of manifestly exotic states; two states appear in the $u d ˉ scc$ sector, three in $u d ˉ sc b$ , and four in $u d ˉ s bb$ . These emerge either as bound states or resonances, along with five additional virtual states manifested as threshold cusps. The binding mechanism is dominated by off-diagonal transitions among heavy-baryon--light-meson channels, while diagonal interactions are strongly suppressed. These results extend exotic hadron spectroscopy into the doubly heavy--strange sector and provide concrete targets for future experimental searches.
↳ hep-phhep-thnucl-th0 citations

Affiliations

first authorsco-authorsvia INSPIRE