Nuclear Theory·nucl-th

Monday·April 20, 2026

12 papers—4 primary·8 cross-listed

05
Systematic Analytic Regularization in $φ^{4}$ and Yukawa Theories
Jarryd Bath🇿🇦 · W. A. Horowitz🇺🇸
We introduce a novel regularization scheme: Systematic Analytic Regularization (SAR). SAR regularizes a theory at the level of the action by analytically continuing the power of the kinetic operator, ensuring that the theory is formally finite before any terms in the Dyson series are evaluated. We demonstrate that SAR fully and self-consistently regularizes $φ^{4}$ and Yukawa theories at NLO.
↳ hep-thhep-phnucl-th0 citations
06
sPHENIX measurement of Open-Charm Baryon-to-Meson Ratios in $p$ + $p$ collisions at RHIC
Xudong Yu (on behalf of the sPHENIX Collaboration)🇨🇳
sPHENIX is a state-of-the-art experiment at the Relativistic Heavy Ion Collider (RHIC), dedicated to the study of heavy-flavor and jet physics. Its precision tracking system, combined with streaming readout, enables heavy-flavor measurements with high-statistics and essentially unbiased data samples. During the 2024 run, sPHENIX was fully commissioned and recorded a sample of 100 billion unbiased $p$ + $p$ collisions, together with a minimum-bias Au+Au dataset. The 2025 run further expanded the sPHENIX dataset with high-statistics $p$ + $p$ , O+O and Au+Au collisions. This extensive $p$ + $p$ sample opens the door to heavy-flavor measurements with orders of magnitude more statistics than previously available at RHIC. Notably, there has been no prior measurement of the $Λ_{c}^{+} / D^{0}$ baseline in $p$ + $p$ collisions at RHIC energies. The large sPHENIX dataset now enables the first exploration of key open questions, such as the hadronization mechanism of baryons and the strange-to-light flavor meson ratio.
↳ nucl-exhep-exnucl-thJ.Subatomic Part.Cosmol.(2026)·0 citations
07
Theoretical modeling of charged current $ν_{μ} (ν ˉ_{μ}) -^{40} A r$ DIS at DUNE energies
F. Zaidi🇮🇳 · S. Akther🇮🇳 · M. Sajjad Athar🇮🇳 · S.K. Singh🇮🇳
The charged current $ν_{μ} (ν ˉ_{μ})$ -induced deep inelastic scattering (DIS) from an $^{40} Ar$ target is studied using a microscopic framework that incorporates nuclear medium effects due to Fermi motion, binding energy, nucleon correlations, mesonic ( $π$ and $ρ$ ) contributions, and nuclear shadowing and antishadowing across the relevant Bjorken- $x$ region. The nuclear structure functions $F_{i A} (x, Q^{2})$ $(i = 1 - 3)$ are evaluated using a relativistic nucleon spectral function ( $S_{h}$ ) within the local density approximation employing the free nucleon structure functions, $F_{i N} (x, Q^{2})$ $(i = 1 - 3)$ . These $F_{i N} (x, Q^{2})$ $(i = 1 - 3)$ are calculated using parton distribution functions (PDFs) from MMHT 2014 parameterization, including higher-order perturbative QCD corrections up to next-to-next-to-leading order (NNLO), along with nonperturbative target mass corrections (TMC). The resulting nuclear structure functions $F_{i A} (x, Q^{2})$ $(i = 1 - 3)$ are subsequently used to compute the differential DIS cross sections for $^{40} A r$ nucleus. Numerical results are presented for $ν_{μ} (ν ˉ_{μ})$ beam energies $E = 4$ GeV and $E = 6$ GeV for the differential scattering cross sections $\frac{d ^{2} σ}{d x d y}$ and $\frac{d σ}{d x}$ , relevant to ongoing and upcoming liquid-argon neutrino experiments such as DUNE and the Fermilab Short-Baseline Neutrino program.
↳ hep-phhep-exnucl-thPRD(2026)·0 citations
08
P-wave $c c ˉ$ meson contributions in exotic hadrons
Kotaro Miyake🇯🇵 · Yasuhiro Yamaguchi🇯🇵
The nature of the $X (3872)$ and other exotic hadrons has been a subject of extensive investigation. While various theoretical models have been proposed, experimental evidence suggests that the $X (3872)$ may be a mixture state of a hadronic molecule and a $c c ˉ$ core. In this work, we perform a systematic study of hidden-charm tetraquark candidates $X (3860)$ , $X (3872)$ , and $Z (3930)$ using a coupled-channel model that incorporates both $c c ˉ$ states and $D^{(*)} D ˉ^{(*)}$ hadronic molecular components. The model parameters are fixed to reproduce the masses of the $X (3872)$ and $Z (3930)$ , and the resulting framework is used to predict the mass and structure of the $0^{++}$ state associated with the $X (3860)$ . Our results support the mixture interpretation of these exotic hadrons, exhibiting strong attractions from the transition potential between $c c ˉ$ and $D^{(*)} D ˉ^{(*)}$ components. The molecular component dominates in the $X (3872)$ , while the $c c ˉ$ component plays a more prominent role in the $X (3860)$ and $Z (3930)$ .
↳ hep-phnucl-thJ.Subatomic Part.Cosmol.(2026)·1 citation
09
Delineating neutral and charged mesons in magnetic fields
Toru Kojo🇯🇵 · Sakura Itatani🇯🇵
We investigate the properties of neutral and charged mesons in magnetic fields, from weak-field to strong-field regimes. To develop analytic insights, we employ a non-relativistic quark model with a confining potential of the harmonic oscillator type. Short-range correlations, such as Coulomb and color-magnetic interactions, are treated as perturbations. In particular, we focus on the magnetic field dependence of the relative and the center-of-mass motions. The qualitative trends differ significantly between neutral and charged mesons: for neutral mesons, the transverse momenta are conserved and continuous, while charged mesons exhibit quantized transverse dynamics. The Zeeman effects, arising from intrinsic spins and orbital angular momenta, are carefully examined. In particular, for charged mesons with spins $s \geq 1$ , we discuss how the zero-point energy in the internal quark motion cancels the Zeeman energy from the orbital angular momentum, ensuring the energetic stability of mesons with high spins. The effectively reduced dimensionality of these mesons in the strong-field limit is also discussed.
↳ hep-phhep-lathep-thnucl-thPRD(2026)·2 citations
10
Exact expectation values in a boost-invariant fluid of Dirac fermions with finite spin density
Andrea Palermo🇫🇷 · Daniele Roselli🇮🇹
We study a boost-invariant, out-of-equilibrium fluid of non-interacting Dirac fermions with a finite canonical spin potential. After solving the Dirac equation in Milne coordinates, we exactly diagonalize the non-equilibrium density operator and compute the partition function and expectation values of relevant observables, including spin polarization, energy density, longitudinal and transverse pressures, spin density, and \emph{spin torque}, i.e. the source of spin non-conservation. We find an analytic expression for the partition function at finite spin potential, and show numerically that thermodynamic relations connecting it to thermodynamic functions hold in the system under consideration. We show that, in a boost-invariant system, both shear-induced polarization and the spin Hall effect are absent, and that a non-vanishing polarization can only arise from a finite spin potential in a free theory. We obtain an analytic expression for the spin polarization as a function of the spin potential in some particular cases, and otherwise compute numerically its exact expectation value at finite spin potential. Our results are discussed in the context of relativistic spin hydrodynamics and quark--gluon plasma phenomenology.
↳ hep-thnucl-thJHEP(2026)·1 citation
11
Testing Scalar Field Self-Dualities in d=2 using a Variational Method
Paul Romatschke🇦🇹 · Ulrike Romatschke🇦🇹
Recently, self-dualities based on saddle-point expansions have been proposed as a means to obtain qualitative non-perturbative information in scalar field theories. In this work, we test this proposition quantitatively by studying the phase transition for critical scalar $ϕ^{4}$ field theory in 1+1 dimensions using a variational method. We find that saddle-point methods obtain quantitative agreement for the free energy, but differ on the order of 25 percent for the peak location of the correlation length.
↳ hep-thhep-latnucl-thPRD(2026)·0 citations
12
Isospin-symmetry violation -- kaons and beyond (ISO-BREAK 25: summary and outlook)
Marek Gazdzicki (1)🇵🇱 · Francesco Giacosa (1)🇵🇱 · Katarzyna Grebieszkow (2)🇵🇱 · David Blaschke (3)🇵🇱 · Marcus Bleicher (4)🇩🇪 · Bastian Brandt (5)🇩🇪 · Wojciech Brylinski · Tobiasz Czopowicz (6)🇵🇱 · Jim Drachenberg (7)🇺🇸 · Dipangkar Dutta (8)🇺🇸 · Francesca Ercolessi (9)🇮🇹 · Mark Gorenstein (10)🇺🇦 and 31 other authors
This report summarizes the presentations and discussions during the ISO-BREAK 25 Workshop ``Isospin symmetry violation: kaons and beyond'', which was held at Jan Kochanowski University in Kielce on October 23-25, 2025. We address the current status of the isospin-symmetry breaking discovered by NA61/SHINE in nucleus-nucleus collisions at the CERN SPS, its confirmation by other experiments and studies in \ee and deep inelastic scattering. In addition, we discuss the theoretical status as well as we outline experimental and theoretical priorities towards understanding this currently unexplained phenomenon.
↳ nucl-exhep-exhep-phnucl-th2 citations

Affiliations

first authorsco-authorsvia INSPIRE