The three-dimensional classical <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="normal">O</mi><mo stretchy="false">(</mo><mi>N</mi><mo stretchy="false">)</mo></mrow></math> model with a boundary has received renewed interest due to the discovery of the extraordinary-log boundary universality class for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>2</mn><mo>≤</mo><mi>N</mi><mo>&lt;</mo><msub><mrow><mi>N</mi></mrow><mrow><mi>c</mi></mrow></msub></mrow></math>. The critical value <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>N</mi><mi>c</mi></msub></math> and the exponent of the boundary correlation function are related to certain amplitudes in the normal universality class. To determine their precise values, we revisit the 3D <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="normal">O</mi><mo stretchy="false">(</mo><mi>N</mi><mo stretchy="false">)</mo></mrow></math> boundary conformal field theory for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>N</mi><mo>=</mo><mn>1</mn></mrow></math>, 2, 3, 4, 5. After substantially improving the accuracy of the boundary bootstrap, our determinations are in excellent agreement with the Monte Carlo results, resolving the previous discrepancies due to low truncation orders. We also use the recent bulk bootstrap results to deduce highly accurate Ising data. Many bulk and boundary predictions are obtained for the first time. Our results demonstrate the great potential of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>η</mi></math> minimization method for many unexplored bootstrap problems in which positivity constraints are absent.

China

Runzhe Hu

Wenliang Li

Accurate Boundary Bootstrap for the Three-Dimensional <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="normal">O</mi><mo stretchy="false">(</mo><mi>N</mi><mo stretchy="false">)</mo></mrow></math> Normal Universality Class

A new measurement of the $^{65}$Cu($\textit{γ}$, $\textit{n}$)$^{64}$Cu photoneutron cross section is performed using quasi-monoenergetic, tunable $\textit{γ}$-ray beams produced at the Shanghai Laser Electron Gamma Source (SLEGS). The energy spectrum of the SLEGS $\textit{γ}$-ray beams incident on the isotopically enriched $^{65}$Cu target is monitored using a BGO detector, while the photoneutron yields are determined with a moderated $^{3}$He detection array with high and flat efficiency. Within the energy range of $10.1 \le E_\gamma \le 17.6$ MeV, the measured $\sigma(E_\gamma)$ data have an uncertainty of $\lesssim 4$ %, and a pronounced giant-dipole peak is observed at $E_\gamma \simeq 16.65$ MeV with a maximal cross section of $\sigma_{\text{max}} \simeq 137$ mb. These photoneutron data are compared with previous experimental results and are employed to extract the $\textit{γ}$-ray strength function of $^{65}$Cu above the neutron threshold. Furthermore, we calculate the radiative neutron capture cross sections and astrophysical reaction rates for $^{64}$Cu, which is a short-lived intermediate nucleus whose reaction rate controls the local abundance distribution in the weak $\textit{s}$-process. It is found that the calculated $^{64}$Cu($\textit{n,}$ $\textit{γ}$)$^{65}$Cu data have an overall agreement with ENDF/B-VIII.0, JEFF-3.3, and TENDL-2023 evaluations, and the corresponding astrophysical reaction rates are consistent with those reported in the JINA REACLIB database.

Yu-Long Shen

Zi-Rui Hao

Qian-kun Sun

Hong-Wei Wang

Long-Xiang Liu

Hang-Hua Xu

Yue Zhang

Sheng Jin

Kai-Jie Chen

Meng-Die Zhou

Zhen-Wei Wang

Meng-Ke Xu

Xiang-Fei Wang

Chang Yang

Pu Jiao

Chun-Wang Ma

Gong-Tao Fan

Zhi-Cai Li

Wen Luo

Photoneutron cross section measurements on $^{65}$Cu: toward understanding ($\textit{n,}$ $\textit{γ}$) cross sections relevant to weak $\textit{s}$-process nucleosynthesis * This work was supported by the National Key Research and Development Program (2023YFA1606901), and the National Natural Science Foundation of China (12575133, 12505144)

We present an investigation of the structural properties of heavy-light ( $$D, D_s, B, B_s$$ ) and heavy-heavy ( $$B_c$$ ) mesons by incorporating the $\textit{V}$-scheme strong coupling constant $$\alpha _V$$ up to the third-loop order ( $$N^3$$ LO). The inclusion of three-loop radiative corrections is critical to achieving perturbative convergence and effectively canceling renormalon-induced instabilities. A central feature of this work is the rigorous calibration of the string tension $\textit{b}$ using the universal scaling ratio $$R_{n_f} = \Lambda _{\overline{\text {MS}}}^{(n_f)}/\sqrt{b}$$ , matched to the non-perturbative Sommer scale $$r_0$$ from FLAG 2024 averages. By integrating these flavor-dependent $$N^3$$ LO refinements ( $$b \approx 0.1951 \pm 0.0369$$ GeV $$^2$$ ) into a variational Cornell potential framework, we demonstrate a systematic“stiffening”of the internal structure and a physical spatial contraction across successive loop orders. Our $$N^3$$ LO results for root-mean-square (RMS) matter radii and charge radii exhibit remarkable agreement with established benchmarks: specifically, the $$B_c$$ charge radius (0.191 fm) and matter radius (0.2967 fm) align closely with light-front predictions and relativistic quark model studies. Evaluation of the Isgur–Wise function reveals that while higher-order corrections primarily reshape the light-quark spectator cloud, the heavy core localization remains dominated by the constituent mass scale.

India

Rishan Choudhury

Pritom Nath

Jugal Lahkar

Variationally improved structure of heavy-light mesons at $$N^3$$ LO: stiffening effects and universal form factors in the $\textit{V}$-scheme

Recent experimental data from <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>MINER</mi><mi>ν</mi><mi mathvariant="normal">A</mi></mrow></math> on transverse kinematics observables across four different nuclear targets—carbon, oxygen, iron, and lead—have been utilized to refine the modeling of final state interaction effects in the nuwro Monte Carlo neutrino event generator. For this purpose, we have developed an event reweighting tool for future applications to adjust the strength of final-state interactions. This study highlights the requirement for stronger nucleon reinteractions than previously assumed, but it still falls within the uncertainty range observed in a study comparing proton transparency measurements. This conclusion has significant implications for both experimental and theoretical work involving nuwro.

Poland

Hemant Prasad

Jan T. Sobczyk

Rwik Dharmapal Banerjee

J. Luis Bonilla

Krzysztof M. Graczyk

Beata E. Kowal

Artur M. Ankowski

Fine-tuning final state interactions model in the nuwro Monte Carlo event generator

We propose and calculate a holographic Krylov complexity in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">N</mi><mo>=</mo><mn>4</mn></math> SYM theory via the proper momentum for motion in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>AdS</mi><mn>5</mn></msub></math> sliced by <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>AdS</mi><mn>3</mn></msub></math>. The motion in an <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>AdS</mi><mn>3</mn></msub></math> subgroup corresponds to the Krylov complexity of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>S</mi><mi>l</mi><mo stretchy="false">(</mo><mn>2</mn><mo stretchy="false">)</mo></math> subsector. The general motion corresponds to the Krylov complexity of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">N</mi><mo>=</mo><mn>4</mn></math> SYM.

Russia

Ali Fatemiabhari

Brazil

Horatiu Nastase

Dibakar Roychowdhury

Holographic Krylov complexity in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">N</mi><mo>=</mo><mn>4</mn></math> SYM theory

In a recent work, we argued that the net quark number gained by a bath of quarks and gluons upon bringing an external static quark probe, while being equal to 1 in the high temperature, deconfined phase, is equal to 0 or 3 in the low temperature, confined phase, depending on the value of the quark chemical potential. This establishes a clear-cut connection between the confinement of a medium as probed by order parameters such as the Polyakov loop, and the ability of that same medium to screen the quark probe into states with the same net quark content as mesons or baryons. In this work, we extend these findings to the SU(<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>N</mi><mi>c</mi></msub></math>) color group, consider color probes in various (fundamental and nonfundamental) representations, and conjecture a rationale of how these results could be recovered from a purely thermodynamic argument that shortcuts the use of the Euclidean functional framework, while emphasizing the role of color <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>N</mi><mi>c</mi></msub></math>-ality as a proxy for center symmetry within the Minkowskian framework.

France

V. Tomas Mari Surkau

Urko Reinosa

SU(<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>N</mi><mi>c</mi></msub></math>) confinement and color <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>N</mi><mi>c</mi></msub></math>-ality

The Georgi-Glashow model is the simplest possible attempt at grand unification. However, due to its particle content, the model preserves a global <math altimg='si63.svg'><mrow><mi>U</mi><msub><mrow><mo>(</mo><mn>1</mn><mo>)</mo></mrow><mrow><mi>B</mi><mo>&#8722;</mo><mi>L</mi></mrow></msub></mrow></math> symmetry, where <italic>B</italic> and <italic>L</italic> are baryon and lepton numbers, respectively. It thus leaves neutrinos massless just as the Standard Model does. The extensions of the Georgi-Glashow model that break lepton number by two units, i.e., scenarios with <math altimg='si64.svg'><mrow><mo>|</mo><mstyle mathvariant='normal'><mi>&#916;</mi></mstyle><mi>L</mi><mo>|</mo><mo>=</mo><mn>2</mn></mrow></math> operator(s), naturally generate potentially viable Majorana neutrino masses. Since the dynamics that yields <math altimg='si64.svg'><mrow><mo>|</mo><mstyle mathvariant='normal'><mi>&#916;</mi></mstyle><mi>L</mi><mo>|</mo><mo>=</mo><mn>2</mn></mrow></math> interactions unavoidably induces <math altimg='si65.svg'><mrow><mo>|</mo><mstyle mathvariant='normal'><mi>&#916;</mi></mstyle><mi>B</mi><mo>|</mo><mo>=</mo><mn>2</mn></mrow></math> transitions via <math altimg='si66.svg'><mrow><mi>B</mi><mspace width='-0.16em' /><mo linebreak='goodbreak'>&#8722;</mo><mspace width='-0.16em' /><mi>L</mi></mrow></math> breaking, these extensions consequentially lead to intriguing processes such as neutron&#8211;antineutron ( <italic>n</italic>&#8211; <math altimg='si1.svg'><mover><mrow><mi>n</mi></mrow><mo stretchy='true'>&#8254;</mo></mover></math>) oscillation. We investigate this intrinsic connection between neutrino mass generation and <italic>n</italic>&#8211; <math altimg='si1.svg'><mover><mrow><mi>n</mi></mrow><mo stretchy='true'>&#8254;</mo></mover></math> oscillation within a number of representative extensions of the Georgi-Glashow model that can yield realistic neutrino masses and mixing parameters. These extensions include the tree-level seesaw mechanism realizations of the Type I, II, and III varieties, as well as the one-loop and two-loop radiative neutrino mass models.

Slovenia

Croatia

Ilja Doršner

Svjetlana Fajfer

Shaikh Saad

Neutrino mass induced <italic>n</italic>&#8211; <math altimg='si1.svg'><mover><mrow><mi>n</mi></mrow><mo stretchy='true'>&#8254;</mo></mover></math> oscillation

We propose an integrability approach for planar three-point functions at finite coupling in $$ \mathcal{N} $$ = 2 superconformal field theories obtained as $\textit{ℤ}$ orbifolds of $$ \mathcal{N} $$ = 4 super Yang-Mills (SYM). Generalizing the hexagon formalism for $$ \mathcal{N} $$ = 4 SYM, we reproduce the structure constants of Coulomb branch operators, previously obtained by supersymmetric localization, as exact functions of the ’t Hooft coupling. Our analysis explains the common physical origin of Fredholm kernels in integrability and localization, and hints at structures after the resummation in the hexagon formalism. Notably, we conjecture an all-loop, all-magnon expression for the wrapping contribution, that we checked against the Fredholm determinant result. We were also able to check that the first few magnon contributions are consistent with the factorized form of the final result.

Germany

Gwenaël Ferrando

Switzerland

Shota Komatsu

Gabriel Lefundes

Didina Serban

Exact three-point functions in $$ \mathcal{N} $$ = 2 superconformal field theories: integrability vs. localization

We develop a manifest supertwistor space formalism for three dimensional $$ \mathcal{N}=1,2,3,4 $$ superconformal field theories. This formalism simultaneously makes manifest the supersymmetry, conformal invariance and conservation. We solve two and three point correlators of (half) integer spin conserved supercurrents using the graded supergroup generators. Apart from the superconformal generators, we find that the superhelicity operators are necessary to fix their functional form in this setup. The superhelicity operators can be recast into first order Euler equations which besides the standard rational solutions, also admit weak solutions that are distributional in nature. They play an important role in the case of three point functions, where the supercorrelator takes the form of a product of delta functions. Interestingly, we find that these supercorrelators are extremely simple, elegant and uniform for all spins and for all $$ \mathcal{N}\le 4 $$ , which resemble the non supersymmetric correlators where the twistors are replaced with appropriately defined supertwistors.

Aswini Bala

Sachin Jain

Dhruva K. S.

Deep Mazumdar

Vibhor Singh

Brijesh Thakkar

A supertwistor formalism for $$ \mathcal{N}=1,2,3,4 $$ SCFT3

Mixed oriented and nonoriented center vortices are known to generate nontrivial topological charge. However, most previous analyses have been restricted to Abelian-projected thin configurations. Studies of thick vortices have so far focused on the <italic>SU</italic>(2) case and on the intersection of a single pair of oriented objects. In this work, we construct mixed oriented and nonoriented thick center-vortex gauge fields in <italic>SU</italic>( <italic>N</italic>) with smooth profiles and explicit non-Abelian phases. These phases ensure a smooth interpolation between different Cartan fluxes at monopole junctions. We analyze the resulting topological charge density and visualize its morphology, elucidating the color structures responsible for fractional lumps that together yield a nonvanishing global charge.

David R. Junior

Luis E. Oxman

Gustavo M. Simões

Thick oriented and nonoriented center-vortex <italic>SU</italic>( <italic>N</italic>) configurations with fractional topological charge lumps