Nuclear Theory·nucl-th

Thursday·March 19, 2026

11 papers—1 primary·10 cross-listed

02
Higher-point Energy Correlators: Factorization in the Back-to-Back Limit & Non-perturbative Effects
Ankita Budhraja🇳🇱 · Isabelle Pels🇳🇱 · Wouter J. Waalewijn🇳🇱
N-point energy correlators are powerful observables for studying strong interactions, with applications ranging from extractions of the strong coupling $α_{s}$ to probes of jet modification in heavy-ion collisions and determination of the top-quark mass. Their practical use has, however, been limited by the complicated phase space for large N. Using a recently introduced parametrization that simplifies this structure, we study projected N-point correlators in two regimes: factorization in the back-to-back limit and leading non-perturbative effects in the collinear limit. While results in the back-to-back regime were previously limited to the energy-energy correlator, our approach allows us to derive the factorization theorem for arbitrary N. We compute the new ingredient, a one-loop jet function, needed for the next-to-next-to-leading-logarithmic resummation, which enables future $α_{s}$ extractions with complementary systematics. We further determine the analytic structure of leading non-perturbative power corrections for arbitrary N, including their dependence on the center-of-mass energy Q, the value of N, and the angular scale $x$ . We present the first results for non-integer N<1, finding that the classical scaling in $x$ acquires an N-dependent modification, and that a new non-perturbative matrix element $Ω ~^{[N]}$ appears. In a certain approximation, $Ω ~^{[N]}$ can be related to the standard parameter $Ω_{1}$ relevant for N>1. Our analytic predictions are tested against the hadronization model in Pythia, finding good agreement. The results presented in this paper demonstrate the significant advancements enabled through our new parametrization of energy correlators.
↳ hep-phhep-exnucl-thJHEP(2026)·4 citations
03
Is the Turner Window Open? Seeking Closure with Resonant Absorption of Galactic Axions in NaI Dark Matter Detectors
W. C. Haxton🇺🇸 · Xing Liu🇺🇸 · Anupam Ray🇨🇦 · Evan Rule🇺🇸
Motivated by the DAMA/LIBRA annual modulation signal, the dark matter community has invested heavily in ultra-clean underground NaI detectors to search for light WIMPs. We point out a new target of opportunity for these detectors -- axions produced by the carbon-burning stars within our galaxy. These stars synthesize large quantities of $^{23}$ Na, keeping it at temperatures $\sim 1 0^{9}$ K for periods up to tens of thousands of years. Under these conditions, $^{23}$ Na radiates 440 keV axions through repeated photo-excitation and axio-deexcitation of its first excited state. Upon reaching a NaI detector, the process is reversed: the axion is resonantly absorbed, producing a 440 keV deexcitation photon. NaI thus serves as both $γ$ source and $γ$ detector. We find that existing NaI detectors can probe axion-nucleon couplings $∣ g_{a N N}^{eff^{23} Na} ∣ \approx g_{a pp} \sim 1 0^{- 6}$ -- $1 0^{- 2}$ , including QCD axions with $m_{a} ≳ 10$ eV. While there are several astrophysical constraints on axions with these couplings, our re-examination of these bounds shows that substantial gaps remain, providing strong motivation for the proposed searches.
↳ hep-phastro-ph.HEhep-exnucl-ex+12 citations
04
Resolving anomalous collectivity in the $4_{1}^{+}$ to $2_{1}^{+}$ transition of $^{58}$ Fe
J. A. Woodside🇦🇺 · B. J. Coombes🇦🇺 · A. E. Stuchbery🇦🇺 · A. J. Mitchell🇦🇺 · M. Reece🇦🇺 · G. J. Lane🇦🇺 · T. J. Gray🇺🇸 · G. Pasqualato🇫🇷 · L. J. McKie🇦🇺 · N. J. Spinks🇦🇺
The low-excitation states of atomic nuclei in the region around the $N = Z = 28$ shell closure are generally well described by the shell model. Most experimental observables in the iron isotopes $^{56}$ Fe, $^{58}$ Fe, and $^{60}$ Fe ( $Z = 26$ ; $N = 30$ , $32$ , $34$ ) support a shell-model description. However, the lifetimes of the $4_{1}^{+}$ state in $^{58}$ Fe in the literature result in a reduced transition strength that deviates markedly from shell-model predictions. There are three independent measurements, all in agreement and all based on the Doppler Shift Attenuation Method (DSAM) or Doppler-Broadened Line Shape method (DBLS). In this work, Coulomb-excitation measurements were performed on $^{56}$ Fe and $^{58}$ Fe beams to determine the ratios $B (E 2; 4_{1}^{+} \to 2_{1}^{+}) / B (E 2; 2_{1}^{+} \to 0_{1}^{+})$ . Thus, $B (E 2; 4_{1}^{+} \to 2_{1}^{+})$ is determined relative to the known $B (E 2; 2_{1}^{+} \to 0_{1}^{+})$ values. For $^{56}$ Fe, $B (E 2; 4_{1}^{+} \to 2_{1}^{+}) = 23 (4)$ W.u., agreeing with the adopted value. However, for $^{58}$ Fe, the $B (E 2; 4_{1}^{+} \to 2_{1}^{+})$ values obtained (for the various combinations of matrix element signs that could not be firmly established) are all significantly lower than the value derived from the previous lifetime measurements, and are in accord with shell-model calculations. The 1978 DSAM measurement of Bolotin et al., Nucl. Phys. A 311, 75 (1978), has been re-examined. The discrepancy between that measurement and the Coulomb-excitation measurement can be ascribed to the Lindhard-Scharff-Schiøtt (LSS) electronic stopping powers adopted for the DSAM analysis, which considerably overestimate contemporary values. Evidently, lifetime measurements from that era that are based on LSS stopping powers should be used with caution. The revised lifetime data, incorporating current stopping powers, are compared with shell-model calculations.
↳ nucl-exnucl-thPRC(2026)·0 citations
05
A Continuum Schwinger Method to Study the Pion's Generalized Parton Distribution
J.M. Morgado-Chávez🇪🇸 · J. Segovia🇪🇸 · F. de Soto🇪🇸 · J. Rodríguez-Quintero🇪🇸 · V. Bertone🇫🇷 · M. Defurne🇫🇷 · C. Mezrag🇫🇷 · H. Moutarde🇫🇷
Generalised Parton Distributions (GPDs) provide multidimensional insight into hadron structure and are particularly relevant for the pion, whose dynamics are intimately linked to chiral symmetry breaking. We introduce a novel modelling strategy for pion GPDs that satisfies all QCD constraints by construction: support, polynomiality, positivity, and the soft-pion theorem. The approach is illustrated with a simple algebraic model, which is evolved and used to compute deeply virtual Compton scattering (DVCS) Compton Form Factors at next-to-leading order. Our results indicate that gluons dominate the pion response at the Electron Ion Collider kinematics.
↳ hep-phhep-exhep-latnucl-ex+1Acta Phys.Polon.Supp.(2026)·0 citations
06
Pseudoscalar and vector toponia in a Dyson--Schwinger--Bethe--Salpeter framework
H.-R. Zhang🇨🇳 · Z.-F. Cui🇨🇳 · J. Segovia🇪🇸
We study the pseudoscalar ( $J^{P C} = 0^{-+}$ ) and vector ( $1^{--}$ ) top--antitop (toponium) systems within the rainbow--ladder truncation of the Dyson--Schwinger and Bethe--Salpeter equations, employing the Qin--Chang effective interaction. After validating the framework in the charmonium and bottomonium sectors, we extend it consistently to the top sector, incorporating renormalisation-group running of the current quark mass and a careful treatment of the number of active flavours. We compute masses and leptonic decay constants for $N_{f} = 5$ and $6$ , then analyse their dependence on the renormalisation scale in the range $μ = 400 - 800 GeV$ . The resulting toponium masses lie near $344 - 346 GeV$ with hyperfine splittings below $0.14 - 0.17 GeV$ , while the decay constants are large, $6 - 7 GeV$ , and exhibit the expected heavy-quark scaling behaviour. We find only mild sensitivity to the renormalisation point and a systematic reduction of binding when increasing $N_{f}$ . Although the physical top quark decays weakly before hadronisation, our results demonstrate that, within a Poincaré-covariant nonperturbative framework, quantum chromodynamics (QCD) generates tightly correlated pseudoscalar and vector toponium systems in that extreme heavy-quark limit.
↳ hep-phhep-exhep-latnucl-ex+1PRD(2026)·2 citations
07
Inclusive heavy meson photoproduction in $pP b$ and $P b P b$ collisions
Victor P. Goncalves🇧🇷 · Luana Santana🇧🇷 · Wolfgang Schäfer🇵🇱
The inclusive photoproduction of heavy mesons in ultraperipheral $pP b$ and $P b P b$ collisions at the LHC energies is investigated considering the color dipole $S$ -matrix formalism and assuming distinct models for the unintegrated gluon distribution, based on different assumptions for the description of the QCD dynamics. In particular, predictions for the $B^{0}$ -meson photoproduction are presented here for the first time. The study of the $D^{0}$ -meson photoproduction is revisited by estimating the impact of the treatment of the heavy charm fragmentation on the predictions and extended for $pP b$ collisions. Moreover, the contribution associated with the $b \to D^{0}$ transition is estimated. Our results indicate that a future experimental analysis of the heavy meson photoproduction will provide important constrains on the description of the hadronic structure at high energies.
↳ hep-phhep-exnucl-exnucl-thPRD(2026)·0 citations
08
ALPHANSO: Open-Source Modeling of ( $α$ ,n) Neutron Source Terms
Divit Rawal · Anthony J. Nelson · William Zywiec · Daniel Siefman
Applications ranging from nuclear safeguards to dark matter detection require accurate predictions of neutron yields and energy spectra produced by ( $α$ ,n) reactions. Legacy tools like SOURCES-4C remain widely used despite significant limitations, including outdated nuclear data, missing target nuclides, and restricted accessibility. Here, we present ALPHANSO, an open-source Python package for calculating ( $α$ ,n) neutron source terms. ALPHANSO incorporates modern nuclear data libraries and formats covering all naturally occurring target nuclides and provides a transparent, modular framework for updating or extending the data as new evaluations are released. Comparison with an updated version of SOURCES-4A, NeuCBOT, and experimental measurements across a range of elements and materials shows that ALPHANSO reproduces neutron yields and spectra in good agreement with experimental data and state-of-the-art ( $α$ ,n) calculations. These results demonstrate that ALPHANSO is a reliable, accessible, and modern alternative to legacy ( $α$ ,n) source term codes such as SOURCES-4C. Its open-source design and modular data handling make it readily extensible to future evaluated nuclear data and low-background applications.
↳ physics.comp-phnucl-exnucl-thNucl.Instrum.Meth.A(2026)·1 citation
09
Hydrodynamics of dilation and spin currents
Zhong-Hua Zhang🇨🇳 · Xi-Hu Lv🇨🇳 · Xu-Guang Huang🇨🇳
We formulate a relativistic hydrodynamic theory for fluids with spin and intrinsic dilation charges. Using an entropy-current analysis, we derive constitutive relations featuring a bulk viscosity and a dilation conductivity governing the relaxation and diffusion of dilation charge. Linear mode analysis reveals a gapped dilation excitation and the freeze-out of long-wavelength sound modes, similar to the superhorizon modes in cosmology. In the nonrelativistic limit, the theory reduces to that of microstretch fluids. Upon coupling to electromagnetic field, we show that the scale anomaly permits additional contributions in the electric current, dilation current, and energy-momentum tensor. Our theory naturally applies to nearly conformal fluids undergoing rapid expansion or contraction.
↳ hep-thcond-mat.softhep-phnucl-th+11 citation
10
Universal scaling of transport coefficients near the liquid-gas critical point
Johannes V. Roth🇩🇪 · Yunxin Ye🇩🇪 · Sören Schlichting🇩🇪 · Lorenz von Smekal🇩🇪
We employ a novel real-time formulation of the functional renormalization group (FRG) to compute universal scaling functions of the thermal diffusivity and the shear viscosity in the vicinity of the liquid-gas critical point, i.e., for the dynamic universality class of Model H from the Halperin-Hohenberg classification. We map out the universal dependence of the transport coefficients on temperature, external magnetic field, and wavenumber, and provide a detailed comparison with the Kawasaki approximation, which is here obtained from a perturbative one-loop approximation to our real-time FRG flow. In contrast to the Kawasaki approximation, the non-perturbative scaling functions from the full real-time FRG flow show a mild dependence on the thermodynamic path towards the critical point. We further compare our FRG results for the universal wavenumber and temperature dependence of the thermal diffusivity with experimental data from critical fluids.
↳ hep-phcond-mat.stat-mechnucl-th2 citations
11
Asymptotics of superfluid Bjorken flow
Alexander Soloviev🇸🇮 · Michał Spaliński🇫🇮
We consider the dynamics of an expanding superfluid modeled by Mueller-Israel-Stewart theory coupled to a complex scalar field with a $U (1)$ symmetry that is spontaneously broken. This is a manageable theoretical setting for explorations of the chiral phase transition of expanding quark-gluon plasma. We study the late proper-time behavior of Bjorken flow in this physical system and find that asymptotic solutions can be expressed as a transseries of a novel form, which contains factors like $τ^{- a l n τ}$ . This transseries describes how the information encoded in the initial data is diluted in the course of dissipative evolution. These solutions retain memory of the symmetry-breaking transition and describe two qualitatively different late-time behaviors of the dynamical variables, depending on condensate relaxation rate: either a purely damped fall-off or damped oscillations. The possibility that such oscillations could be imprinted in the observed outcomes of heavy ion collision experiments is the main physical insight that follows from our analysis.
↳ hep-thhep-phnucl-thPRD(2026)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE