Nuclear Theory·nucl-th

Friday·July 3, 2026

10 papers—6 primary·4 cross-listed

07
[Submitted on 1 Jul 2026] (cross-list from hep-ph)
The theory of electric dipole moments: the view from below
Jordy de Vries🇳🇱
Permanent electric dipole moments (EDMs) of nucleons, nuclei, atoms, and molecules are among the most sensitive probes of CP violation beyond the Standard Model and are intimately connected to the strong CP problem and the origin of the matter-antimatter asymmetry of the universe. This review presents the theory of EDMs from the bottom up, tracing the chain of connections that links CP-violating interactions at level of elementary particles to observable EDMs across a wide range of systems. Starting from a general CP-odd effective Lagrangian at the quark-gluon level comprising the QCD theta term, quark EDMs and chromo-EDMs, the Weinberg operator, and CP-odd four-fermion interactions, I show how chiral perturbation theory organizes the nonperturbative QCD dynamics into a small set of hadronic low-energy constants, whose relative sizes are determined by the chiral representation of the underlying source. These hadronic interactions feed into calculations of nuclear EDMs and Schiff moments, which in turn enter atomic and molecular structure calculations that connect to experimentally accessible observables in diamagnetic and paramagnetic systems. Special attention is given to the recently identified sensitivity of paramagnetic systems to hadronic CP violation, which opens a new and relatively unexplored window on the quark-gluon sector. The complementarity of the full EDM portfolio including the neutron, light nuclei, atoms, and molecules, and the role of theory in disentangling the underlying source of CP violation is discussed throughout.
Comments:
24 pages, Chapter for the Encyclopedia of Nuclear Physics
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); Atomic Physics (physics.atom-ph)
arXiv:
2607.01443 [pdf]
0 citations
08
[Submitted on 2 Jul 2026] (cross-list from hep-ph)
$Λ$ hyperons in core-collapse supernovae: Equilibration and neutrino opacities
Ruben Zatini🇪🇸 · Jorge Martin Camalich🇪🇸 · Pasquale Dario Serpico🇫🇷 · Tobias Fischer🇵🇱
Strange hadrons are commonly included in dense-matter equation-of-state models by imposing chemical equilibrium, but the weak-interaction timescales required to establish it in core-collapse supernovae have not been systematically assessed. In this paper we compute the $Λ$ -hyperon production rates in the hot, dense, and isospin-asymmetric conditions characteristic of post-collapse proto-neutron stars. We find that local $Λ$ chemical equilibration is driven by nonleptonic strangeness-changing reactions, especially $N N \leftrightarrow N Λ$ scattering, on timescales of order $1 0^{- 11}$ - $1 0^{- 10}$ s, many orders of magnitude shorter than macroscopic proto-neutron-star evolution timescales. Using an effective-field-theory framework constrained by hypernuclear weak-decay data, we find that short-range contact interactions dominate the nonleptonic rates, beyond a pure one-meson-exchange description. Semileptonic channels are too slow to set the equilibrium $Λ$ abundance, but they open additional absorption channels for low-energy muon neutrinos and antineutrinos, such as $ν_{μ} + Λ \to μ^{-} + p$ and $p + μ^{-} + ν ˉ_{μ} \to Λ$ . At low energies, these $Λ$ -induced neutrino opacities exceed the corresponding nucleonic contributions for muon (anti)neutrinos, possibly influencing the evolution of the muon lepton number during proto-neutron-star deleptonization. These results support local chemical equilibrium for $Λ$ hyperons under the conditions studied and provide new weak-interaction input for flavor-dependent neutrino transport, muonization, and proto-neutron-star evolution.
Comments:
20 pages, 4 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2607.02086 [pdf]
0 citations
09
[Submitted on 2 Jul 2026] (cross-list from hep-ph)
A Maximum-Entropy Method for Zero-Skewness Valence GPDs Constrained by Nucleon Electromagnetic Form Factors
Seung-il Nam🇰🇷
We formulate a reduced-profile maximum-entropy method (MEM) framework for constructing constrained zero-skewness valence-quark generalized parton distribution (GPD) transverse profiles from the four nucleon electromagnetic form factors $F_{1}^{p} (t)$ , $F_{1}^{n} (t)$ , $F_{2}^{p} (t)$ , and $F_{2}^{n} (t)$ . The form-factor sum rules fix only $x$ -integrated moments of the GPDs; the forward limit of $H_{v}^{q}$ is fixed separately by the valence parton distribution functions, and the normalization of $E_{v}^{q}$ by the flavor anomalous magnetic moments. These complementary constraints are combined through the ansatz $H_{v}^{q} (x, t) = q_{v} (x) exp [t f_{H}^{q} (x)]$ and $E_{v}^{q} (x, t) = e_{v}^{q} (x) exp [t f_{E}^{q} (x)]$ , where the positive profile functions encode the $x$ -dependent transverse structure. Rather than attempting an unrestricted functional inversion, we use the entropy functional as a regularizing criterion on a low-dimensional positive profile manifold. In the numerical proof-of-concept calculation, a smooth elastic form-factor input and analytic forward distributions are adopted, together with the reduced form $f (x) = 0.05 + (1 - x)^{2} exp (c_{0} + c_{1} x + c_{2} x^{2})$ , which suppresses local modes that elastic moments alone cannot constrain. Within this reduced ansatz, the resulting profiles reproduce the imposed elastic moment constraints, satisfy the forward normalizations after discrete-grid normalization, and give impact-parameter distributions with the expected transverse shrinkage at large $x$ . The construction provides a controlled zero-skewness baseline for connecting elastic form-factor constraints to $x$ -dependent transverse profiles, and it offers a stable starting point for future analyses incorporating empirical form-factor fits, modern PDF inputs, lattice-QCD generalized form factors, and hard exclusive observables.
Comments:
15 pages, 3 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2607.02302 [pdf]
0 citations
10
[Submitted on 2 Jul 2026] (cross-list from hep-ph)
Event-axis TMD measurements in $e^{+} e^{-}$ and SIDIS
Daniel Diaz Fernandez🇪🇸 · Patricia Andrea Gutierrez Garcia🇪🇸 · Ignazio Scimemi🇪🇸 · Wouter Waalewijn🇳🇱
Transverse-momentum-dependent (TMD) fragmentation in $e^{+} e^{-}$ collisions can be studied by measuring hadrons with respect to the thrust axis, and has been measured at Belle. This provides a complementary way to extract TMD fragmentation functions, avoiding the need to disentangle the two TMD fragmentation functions that enter conventional back-to-back hadron-pair measurements. Starting from the established factorization theorems for this observable, we complete the operator-level formulation of the soft ingredients and perform one-loop checks using the $δ$ -regulator. We also extend existing results for 1-jettiness factorization in semi-inclusive deep-inelastic scattering (SIDIS), where analogous measurements give access to the TMD parton distribution functions of the incoming hadron. For phenomenology, we discuss the nonperturbative effects and propose a model that captures both the event-shape dependence and correlations between the event-shape and transverse-momentum measurements. We resum the transverse-momentum and thrust logarithms, explore several schemes for treating the latter, and implement it in artemide. As a first validation, we compare to simulated $e^{+} e^{-}$ data from Pythia8.3. We find that the proposed nonperturbative model is flexible enough to describe the simulated data, with fitted parameters of the expected size in powers of $Λ_{QCD} / Q$ . In this test, the resummation of the logarithms of $q_{T} / (τ Q)$ appears to have little impact on the fit quality, but changes the fit parameters.
Comments:
30 pages, 7 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2607.02438 [pdf]
0 citations

Affiliations

first authorsco-authorsvia INSPIRE

The theory of electric dipole moments: the view from below

Λ hyperons in core-collapse supernovae: Equilibration and neutrino opacities

A Maximum-Entropy Method for Zero-Skewness Valence GPDs Constrained by Nucleon Electromagnetic Form Factors

Event-axis TMD measurements in e+e− and SIDIS

Affiliations

$Λ$ hyperons in core-collapse supernovae: Equilibration and neutrino opacities

Event-axis TMD measurements in $e^{+} e^{-}$ and SIDIS