In this work, the electromagnetic and gravitational form factors of $$\Delta $$ isobars, as well as the electromagnetic $$N-\Delta $$ transition form factors, are studied systematically and continuously using a covariant quark–diquark approach with the pion cloud effect. In our model, the baryon is treated as a two-body system to simplify calculations, and the quarks are assumed to be surrounded by the pion cloud. The related physical properties, such as the charge radius and magnetic moment of $$\Delta (1232)$$ and the helicity amplitudes of the $$N-\Delta $$ transition, are obtained and discussed. Our results for the form factors of both $$\Delta (1232)$$ and the electromagnetic $$N-\Delta $$ transition are in reasonable agreement with the experimental and lattice results. Moreover, we found that the pion cloud plays an important role in the results by increasing the magnetic transition form factor $$G_M(t)$$ and shifting the sign of the D-term of $$\Delta $$ to negative.

China

Jiaqi Wang

Dongyan Fu

Yubing Dong

Form factors of $$\Delta (1232)$$ and the electromagnetic $$N-\Delta $$ transition

We calculate the resummed perturbative free energy of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">N</mi><mo>=</mo><mn>4</mn></math> supersymmetric Yang-Mills in four spacetime dimensions (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>SYM</mi></mrow><mrow><mn>44</mn></mrow></msub></mrow></math>) to order <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>λ</mi><mrow><mn>5</mn><mo>/</mo><mn>2</mn></mrow></msup></math> in the ‘t Hooft coupling at finite temperature and zero chemical potential. All infrared divergences cancel when we include contributions from <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>SYM</mi></mrow><mrow><mn>44</mn></mrow></msub></mrow></math> ring diagrams and the final result is both ultraviolet and infrared finite. Our result has special significance since order <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>λ</mi><mrow><mn>5</mn><mo>/</mo><mn>2</mn></mrow></msup></math> is the highest order calculation that can be done with perturbation theory, because there are nonperturbative effects associated with the magnetic mass scale that come into play at order <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>λ</mi><mn>3</mn></msup></math>. We compare results obtained with regularization by dimensional reduction (RDR), which preserves supersymmetry, and canonical dimensional regularization (DR). We also compare with a generalized Padé approximant constructed by matching the weak coupling result at order <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>λ</mi><mn>2</mn></msup></math> and the large <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>N</mi><mi>c</mi></msub></math> strong coupling result at order <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>λ</mi><mrow><mo>−</mo><mn>3</mn><mo>/</mo><mn>2</mn></mrow></msup></math>. Finally we make a comparison between our result and the QCD free energy and show that <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>SYM</mi></mrow><mrow><mn>44</mn></mrow></msub></mrow></math> has better convergence properties.

Canada

Margaret E. Carrington

Gabor Kunstatter

Saudi Arabia

Ubaid Tantary

<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="script">N</mi><mo>=</mo><mn>4</mn></mrow></math> supersymmetric Yang-Mills thermodynamics to order <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>λ</mi><mrow><mn>5</mn><mo>/</mo><mn>2</mn></mrow></msup></math>

We study Dirac fields on <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>AdS</mi></mrow><mrow><mi>n</mi></mrow></msub></mrow></math> in both global and Poincaré charts and, for each mass window, we classify the boundary conditions at conformal infinity that ensure the existence of advanced and retarded propagators. We distinguish the well-known MIT–bag class from a generalized family, thereby extending to arbitrary dimensions the procedure initiated in [D. S. Blanco, <a href="http://dx.doi.org/10.1063/5.0135971">J. Math. Phys. (N.Y.) 64, 032301 (2023)</a>.]. As in the scalar case, we show that suitable generalized boundary data can support bound states. In four dimensions, we work out two explicit examples: (i) the MIT case, for which we construct the advanced/retarded propagators and the two-point function of the associated ground state and (ii) a representative generalized boundary condition, for which we construct the propagators and exhibit a normalizable bound state.

Italy

Claudio Dappiaggi

Andrea Parpinel

Boundary conditions and Dirac fields on <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>AdS</mi></mrow><mrow><mi>n</mi></mrow></msub></mrow></math>

We investigate multipartite total amount of correlations by analyzing the mutual information of N-partite states for both free bosonic and fermionic fields in the background of a Garfinkle-Horowitz-Strominger (GHS) dilaton black hole. Focusing on multipartite GHZ and W states, we examine how the Hawking effect influences the N-partite mutual information when one observer hovers near the event horizon while the remaining observers stay in the asymptotically flat region. By tracing over the inaccessible modes inside the event horizon, we derive analytical expressions for the N-partite mutual information in dilaton spacetime for both bosonic and fermionic fields. Our results show that fermionic mutual information is larger than its bosonic counterpart under the influence of the dilaton black hole, whereas the fermionic relative entropy of coherence (REC) is smaller than the bosonic REC. Moreover, the mutual information of GHZ states is consistently larger than that of W states, while the REC of GHZ states is smaller than that of W states in curved spacetime. These findings reveal distinct behaviors of multipartite mutual information and quantum coherence for different particle statistics and multipartite state structures under gravitational effects, providing further insight into many-body total correlations in curved spacetime.

Xiao-Wei Teng

Rui-Yang Xu

Hui-Chen Yang

Shu-Min Wu

Bosonic and fermionic mutual information of N-partite systems in dilaton black hole background

We study two-body scattering as an SU(N)-equivariant map acting on tensor-product representation spaces and analyze the entanglement generated by the $\textit{S}$-matrix. This representation-theoretic perspective separates group structure from dynamics: the decomposition of $\textit{R}$⊗$\textit{R}$′ fixes the invariant operator algebra and therefore the qualitative entangling power of the process. For particles in the fundamental representation, End ($\textit{N}$⊗$\textit{N}$) = Span{𝕀, 𝕊}, so only the identity and swap directions preserve separability, whereas generic combinations generate entanglement. Adjoint-adjoint scattering involves a larger invariant algebra involving $\textit{d}$-tensors and is intrinsically entangling. In Yang-Mills theory one can use color-kinematics duality to show that the color kernel lies on a fixed ray of this operator space, yielding a universal maximum of the outgoing entanglement for scattering at right angles, $$ {E}_{\star}^{(2)}=\frac{3}{4} $$ for SU(2) and $$ {E}_{\star}^{(3)}\simeq 0.91 $$ , independent of kinematics. Dimension-six operators preserve this universality, while dimension-eight deformations populate new color sectors and shift $$ {E}_{\star}^{(N)} $$ , suggesting that entanglement in color space functions as a tomographic probe of effective operators. In helicity space, requiring maximally entangled inputs to scatter into maximally entangled outputs uniquely selects the Yang-Mills quartic coupling and enforces the color Jacobi identity, restating the on-shell Ward constraints as conditions on entanglement preservation. Our results suggest that the information-theoretic viewpoint unifies algebraic, geometric, and dynamical aspects of scattering.

United States

Kun-Feng Lyu

Rahul Muraleedharan

Kuver Sinha

Entanglement, Yang-Mills, and the scattering matrix as an SU(N)-equivariant kernel

Recently, a semi-microscopic structure model has been presented to study the structure of a weakly-bound, two-body nucleus with a deformed core, including Pauli-blocking effects. The model has been successfully applied within the adiabatic distorted wave approximation (ADWA) reaction framework to study the reactions 16C(d, p) 17C, restricting the analysis to bound states of the residual 17C nucleus. In these calculations, the structure of 17C is described using the recently presented semimicroscopic Nilsson+AMD model (NAMD), considering different Pauli-blocking methods. In the present work, the analysis is extended to unbound states of this nucleus with the aim of constraining the location of the 1 <italic>d</italic> <inf>3/2</inf> single-particle strength and infer the <math altimg='si3.svg'><mrow><mi>N</mi><mo linebreak='goodbreak'>=</mo><mn>16</mn></mrow></math> shell-gap. Comparing the measured energy differential cross section for this reaction with calculations in which the position of the 1 <italic>d</italic> <inf>3/2</inf> orbital is arbitrarily varied, we conclude that a large shell-gap (&#8239;&gt;&#8239;5 MeV) is required, in agreement with recently reported value from [J. Lois-Fuentes et al., Phys. Lett. B 867, 139600 (2025)].

Spain

P. Punta

J.A. Lay

A.M. Moro

J. Lois-Fuentes

B. Fernández-Domínguez

Constraining the N=16 shell gap in 17C via transfer to the continuum in the 16C( <italic>d, p</italic>) 17C reaction

We calculate the large-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>N</mi></math> expansion of the sphere free energy <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>F</mi><mo>=</mo><mo>−</mo><mi>log</mi><msub><mi>Z</mi><msup><mi>S</mi><mi>d</mi></msup></msub></math> of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">O</mi><mo stretchy="false">(</mo><mi>N</mi><mo stretchy="false">)</mo><msup><mi>ϕ</mi><mn>4</mn></msup></math> and the Gross-Neveu <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">(</mo><mover accent="true"><mi>ψ</mi><mo stretchy="false">¯</mo></mover><mi>ψ</mi><msup><mo stretchy="false">)</mo><mn>2</mn></msup></math> conformal field theories (CFTs) to order <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>1</mn><mo>/</mo><mi>N</mi></math>. Analytic regularization of these theories requires consistently shifting the UV scaling dimension of the auxiliary field: this can only be done by modifying its kinetic term. This modification combines with the counterterms to give the result that matches the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>ε</mi></math> expansion, resolving a puzzle raised by Tarnopolsky. These <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>F</mi></math>’s can be written compactly in terms of the anomalous dimensions, for both the short- and long-range versions of these CFTs. We also provide various technical results including a computation of the counterterms on the sphere and a neat derivation of the sphere free energy of a free conformal field. Finally, we observe that the long-range CFT becomes the short-range CFT at exactly the point where its <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mover accent="true"><mi>F</mi><mo stretchy="false">˜</mo></mover><mo>=</mo><mo>−</mo><mi>sin</mi><mfrac><mrow><mi>π</mi><mi>d</mi></mrow><mn>2</mn></mfrac><mi>F</mi></math> is maximized as a function of the vector’s scaling dimension.

United Kingdom

Ludo Fraser-Taliente

Sphere free energy of vector models to order <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>1</mn><mo>/</mo><mi>N</mi></math>

The neutron-capture reaction 140Ce(n, <italic>&#947;</italic>) is a key input for <italic>s</italic>-process nucleosynthesis due to its low capture probability, and has been discussed as a possible origin of the discrepancy between predicted and observed stellar cerium abundances. This discrepancy motivated a recent activation measurement at <italic>kT</italic>&#8239;&#8776;&#8239;34 keV and a time-of-flight (TOF) measurement, which reported conflicting Maxwellian-averaged cross sections (MACS), leading to large differences at the astrophysically relevant temperature of <italic>kT</italic>&#8239;&#8776;&#8239;8 keV. In this work, the 140Ce(n, <italic>&#947;</italic>) and 142Ce(n, <italic>&#947;</italic>) cross sections were measured using an activation technique with a quasi-Maxwellian neutron source at <italic>kT</italic>&#8239;&#8776;&#8239;11 keV, produced via the 18O(p,n) reaction. A natCe sample was irradiated at the PTB Ion Accelerator Facility, and the induced activities were measured by an ultra-low-background HPGe detector at the Felsenkeller underground laboratory. Cross sections were determined relative to the 197Au(n, <italic>&#947;</italic>) standard and used to derive MACS values. The resulting MACS of 22.2(1.2) mb at <math altimg='si5.svg'><mrow><mi>k</mi><mi>T</mi><mo linebreak='goodbreak'>=</mo><mn>10</mn></mrow></math> keV is higher than the value previously adopted in stellar models, indicating that the observed 140Ce abundance discrepancy is unlikely to originate from an overestimated neutron-capture cross section. The present result also provides a direct test of the widely used MACS extrapolation procedure from &#8239;&#8764;&#8239;30 keV to &#8239;&#8764;&#8239;8 keV and offers a unique insight into its reliability and potential limitations.

Israel

I. Goldberg

Germany

M. Pichotta

D. Bemmerer

A. Honig

B. Lutz

E. Pirovano

S. Röttger

M. Friedman

Direct measurement of the 140Ce(n, <italic>&#947;</italic>) cross section at <italic>kT</italic> &#8239;&#8776;&#8239;11 keV

We consider the 𝒩 = 4 SYM theory with gauge group Sp($\textit{N}$) and the 𝒩 = 2 superconformal field theory consisting of four hypermultiplets in the fundamental representation and one hypermultiplet in the rank-two antisymmetric representation of the Sp($\textit{N}$) gauge group. Building on previous results obtained via supersymmetric localization and a Toda equation, we determine the leading non-perturbative corrections at strong coupling to the integrated correlator between a Wilson line and two Higgs-branch moment map operators. In the case of the 𝒩 = 2 SCFT, the presence of truncated asymptotic expansions led us to develop a resurgent method complementary to Cheshire cat resurgence. This approach has the advantage of yielding an exact expression for the correlator in terms of an analytic function, which can subsequently be expanded in the strong-coupling regime.

Lorenzo Lillo

Alessandro Pini

Non-perturbative corrections to line defect integrated correlators in Sp($\textit{N}$) SCFTs

We calculate the correction exponents in the chiral Heisenberg model in the 1/$\textit{N}$ expansion. These exponents are related to the slopes of $$\beta $$ functions at the phase transition point. We present the results at order $$1/N^2$$ and check that they agree with the results of the $$\epsilon $$ expansion near $$d = 4$$ . We find that one of the correction exponents diverges as $$d \rightarrow 3$$ . We argue that the appearance of the pole is a rather general phenomenon and is associated with operator mixing involving the system of four-fermion operators. After analyzing the operator mixing structure, we propose a resummation procedure which modifies the exponents already at $\textit{leading order}$. We also perform calculations directly in the three-dimensional model and find complete agreement with the resummed exponents.

Alexander Manashov

Leonid Shumilov

Correction exponents in the chiral Heisenberg model at $$1/N^2$$ : singular contributions and operator mixing