The beyond-the-standard-model scenario presented in this work is motivated by the observations of neutrino masses, the anomalous magnetic moments of the electron and muon, and dark matter in the Universe. We explain these observations by extending the standard model with two generations of vector-like fermions and an inert scalar doublet, all of which are odd under a $Z_2$ symmetry. The light neutrino masses and mixings are generated radiatively while maintaining consistency with bounds on lepton flavor violation. Loop diagrams featuring the same fields also explain the anomalous magnetic moments. Similarly, the correct dark matter relic abundance is reproduced without conflicting with direct detection constraints, or those from big bang nucleosynthesis or cosmic microwave background observations. Finally, prospective signatures at the LHC are discussed.

India

Vandana Sahdev

Neutrino masses, anomalous magnetic moments and dark matter with vector-like fermions and an inert scalar doublet * V.S. acknowledges the support from research grant no. CRG/2018/004889 of the SERB, India; T.R. Seshadri for providing resources during the initial stages of the work; and Brajesh Choudhary for providing access to computers bought under the aegis of Grant No. SR-MF/PS-0212014-DUB (G) of the DST (India)

Uncovering physical laws from experimental data is a fundamental goal of theoretical physics. In this work, we apply the spline-based, interpretable Kolmogorov–Arnold Network (KAN) to investigate the algebraic structure underlying the baryon octet and decuplet mass spectra. Within a symbolic regression framework and without imposing theoretical priors, KAN recovers a symbolic representation equivalent to the classical Gell-Mann–Okubo mass relations, which can be transformed into the standard form through algebraic rearrangement. Compared with conventional fitting approaches, this method achieves comparable predictive accuracy while providing substantially improved interpretability and analytical transparency. Our results demonstrate the potential of KAN as a powerful tool for symbolic discovery in hadron physics and for bridging data-driven modeling with fundamental physical laws.

China

Jian-Yao He

Italy

Xun Chen

Xiao-Yan Zhu

Wen Luo

Discovering the Gell-Mann–Okubo formula with Kolmogorov-Arnold networks * Supported by the National Natural Science Foundation of China (NSFC) (12405154) and the European Union – Next Generation EU through research grant (P2022Z4P4B), ''SOPHYA - Sustainable Optimised PHYsics Algorithms: fundamental physics to build an advanced society'', under the PRIN 2022 PNRR program of the Italian Ministero dell'Università e Ricerca (MUR)

The rare exclusive decay of the Higgs boson, $ H \to J/\psi + \gamma $ , is a crucial channel for assessing the Yukawa coupling of the charm quark. In this article, we examine this process up to the next-to-next-to-leading order (NNLO) in QCD utilizing the Principle of Maximum Conformality (PMC). The PMC offers a systematic approach to eliminate renormalization scale uncertainties by resumming non-conformal $\textit{β}$ contributions into the QCD running coupling through the renormalization group equation (RGE). A PMC scale of $ Q_\star = 3.29\ {\rm{GeV}} $ is obtained, which reflects the low virtuality of the underlying QCD dynamics in the $ H \to J/\psi + \gamma $ process. Notably, this is an order of magnitude smaller than the scale estimated using the conventional method, $\textit{i.e.}$, $ \mu_r = m_H/2 $ . By removing the non-conformal $ \{\beta_i\} $ -terms from the perturbative QCD (pQCD) series, we observe that the PMC NLO QCD correction term is significantly enhanced, while the PMC NNLO QCD correction is suppressed. This indicates improved convergence of the pQCD series up to NNLO. Finally, we calculate the decay width $ \Gamma(H \to J/\psi + \gamma) = $ $ 14.183^{+0.249}_{-0.347} \pm 0.022 $ eV, where the first uncertainty arises from the factorization scale $ \mu_\Lambda \in [1, 2]\ {\rm{GeV}} $ , and the second is due to the estimation of unknown higher-order terms using the Pad $ \acute{e} $ approximant approach. The corresponding branching fraction is $ {\cal{B}}(H \to J/\psi + \gamma) = 3.485_{-0.161}^{+0.152} \times 10^{-6} $ .

Wen-Yuan Li

Ting Sun

Sheng-Quan Wang

Jian-Ming Shen

Hua Zhou

Xing-Gang Wu

Leonardo Di Giustino

Analysis of $\textit{H}$ → $\textit{J}$/$\textit{ψ}$ + $\textit{γ}$ up to Next-to-Next-to-Leading order QCD corrections * Supported in part by the Natural Science Foundation of China (12265011, 12175025, 12347101); the Project of Guizhou Provincial Department of Science and Technology (YQK[2023]016, ZK[2023]141, CXTD[2025]030); the Hunan Provincial Natural Science Foundation (2024JJ3004); the YueLuShan Center for Industrial Innovation (2024YCII0118), and the Natural Science Foundation of Sichuan Province (2024NSFSC1367)

In this article we develop a worldline technique based on the method of images to study the effective action associated to Yang–Mills theories on manifolds with boundaries. We consider the possibility of having either relative or absolute boundary conditions, which are particular types of mixed boundary conditions. Both vector fields and ghost fields are taken into account in this analysis. As a check of our construction, we compute the first three Seeley–DeWitt coefficients of the heat kernel asymptotics. Finally, we employ our technique to calculate the rate of gluon production due to a chromoelectric field background in the presence of a boundary.

Argentina

Santiago Christiansen Murguizur

Lucas Manzo

Pablo Pisani

Worldline images for Yang–Mills theory within boundaries

This Letter presents a combination of searches for Higgs boson pair (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>H</mi><mi>H</mi></math>) production performed by the ATLAS and CMS Collaborations using proton-proton collision datasets recorded at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msqrt><mi>s</mi></msqrt><mo>=</mo><mn>13</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi></math> during the Large Hadron Collider Run 2, corresponding to integrated luminosities ranging between 126 and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>140</mn><mtext> </mtext><mtext> </mtext><msup><mi>fb</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></math>. The upper limit at the 95% confidence level on the total <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>H</mi><mi>H</mi></math> signal strength, defined as the ratio of the measured cross section to the standard model (SM) prediction, corresponds to 2.5, with an expected value of 1.7 (2.8) assuming the absence (presence) of the SM <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>H</mi><mi>H</mi></math> signal. The strength of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>H</mi><mi>H</mi></math> signal is measured to be <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mn>0.8</mn><mrow><mo>−</mo><mn>0.7</mn></mrow><mrow><mo>+</mo><mn>0.9</mn></mrow></msubsup></math> relative to the SM prediction. The observed significance is found to be 1.1 standard deviations whereas 1.3 are expected for the SM <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>H</mi><mi>H</mi></math> signal. Constraints are set on the Higgs boson trilinear self-coupling and on the couplings of two Higgs bosons to two vector bosons, both normalized to the SM predictions and denoted as <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>κ</mi><mi>λ</mi></msub></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>κ</mi><mrow><mn>2</mn><mi>V</mi></mrow></msub></math>, respectively. The observed individual constraints at the 95% confidence level are <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo>−</mo><mn>0.71</mn><mo>&lt;</mo><msub><mrow><mi>κ</mi></mrow><mrow><mi>λ</mi></mrow></msub><mo>&lt;</mo><mn>6.1</mn></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>0.73</mn><mo>&lt;</mo><msub><mi>κ</mi><mrow><mn>2</mn><mi>V</mi></mrow></msub><mo>&lt;</mo><mn>1.3</mn></math>, while the expected constraints assuming the presence of the SM <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>H</mi><mi>H</mi></math> signal are <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo>−</mo><mn>1.3</mn><mo>&lt;</mo><msub><mi>κ</mi><mi>λ</mi></msub><mo>&lt;</mo><mn>6.7</mn></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>0.66</mn><mo>&lt;</mo><msub><mi>κ</mi><mrow><mn>2</mn><mi>V</mi></mrow></msub><mo>&lt;</mo><mn>1.4</mn></math>.

France

G. Aad

Norway

E. Aakvaag

United States

B. Abbott

United Arab Emirates

S. Abdelhameed

Germany

K. Abeling

N.J. Abicht

S.H. Abidi

M. Aboelela

Morocco

A. Aboulhorma

Israel

H. Abramowicz

B.S. Acharya

A. Ackermann

C. Adam Bourdarios

Poland

L. Adamczyk

S.V. Addepalli

United Kingdom

M.J. Addison

J. Adelman

Türkiye

A. Adiguzel

T. Adye

A.A. Affolder

Y. Afik

Spain

M.N. Agaras

A. Aggarwal

Romania

C. Agheorghiesei

A. Ahmad

F. Ahmadov

S. Ahuja

X. Ai

G. Aielli

A. Aikot

M. Ait Tamlihat

B. Aitbenchikh

Sweden

T.P.A. Åkesson

Japan

D. Akiyama

N.N. Akolkar

S. Aktas

G.L. Alberghi

Canada

J. Albert

Switzerland

U. Alberti

P. Albicocco

G.L. Albouy

S. Alderweireldt

Z.L. Alegria

CERN

M. Aleksa

I.N. Aleksandrov

C. Alexa

Greece

T. Alexopoulos

F. Alfonsi

M. Algren

M. Alhroob

Czechia

B. Ali

H.M.J. Ali

S. Ali

S.W. Alibocus

South Africa

M. Aliev

G. Alimonti

C. Allaire

B.M.M. Allbrooke

D.R. Allen

J.S. Allen

J.F. Allen

Australia

C.S. Alley

E.R. Almazan

A. Aloisio

F. Alonso

C. Alpigiani

Z.M.K. Alsolami

A. Alvarez Fernandez

M. Alves Cardoso

M.G. Alviggi

M. Aly

Brazil

Y. Amaral Coutinho

A. Ambler

C. Amelung

M. Amerl

T. Amezza

B. Amini

K. Amirie

A. Amirkhanov

Portugal

S.P. Amor Dos Santos

D. Amperiadou

S. An

C. Anastopoulos

T. Andeen

J.K. Anders

A.C. Anderson

A. Andreazza

S. Angelidakis

A. Angerami

A.V. Anisenkov

A. Annovi

C. Antel

E. Antipov

M. Antonelli

F. Anulli

M. Aoki

T. Aoki

M.A. Aparo

L. Aperio Bella

Combination of ATLAS and CMS Searches for Higgs Boson Pair Production at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msqrt><mrow><mi>s</mi></mrow></msqrt><mo>=</mo><mn>13</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi></mrow></math>

Inverse beta decay (IBD), <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mover accent="true"><mi>ν</mi><mo stretchy="false">¯</mo></mover><mi>e</mi></msub><mi>p</mi><mo stretchy="false">→</mo><msup><mi>e</mi><mo>+</mo></msup><mi>n</mi><mrow><mo stretchy="false">(</mo><mi>γ</mi><mo stretchy="false">)</mo></mrow></math>, is the main detection channel for reactor antineutrinos in water- and hydrocarbon-based detectors. As reactor antineutrino experiments now target sub-percent-level sensitivity to oscillation parameters, a precise theoretical description of IBD, including recoil, weak magnetism, nucleon structure, and radiative corrections, becomes essential. In this work, we give a detailed and precise calculation of the total and differential cross sections for radiative IBD, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mover accent="true"><mi>ν</mi><mo stretchy="false">¯</mo></mover><mi>e</mi></msub><mi>p</mi><mo stretchy="false">→</mo><msup><mi>e</mi><mo>+</mo></msup><mi>n</mi><mi>γ</mi></math>. We use a heavy baryon chiral perturbation theory framework, systematically incorporating electroweak, electromagnetic, and strong-interaction corrections. We derive new analytic cross-section expressions, clarify the collinear structure of radiative corrections, and provide a systematic uncertainty analysis. We also discuss phenomenological applications for reactor antineutrino experiments, e.g., JUNO, and neutron decay. Our results enable subpermille theoretical precision, supporting current and future experiments.

Oleksandr Tomalak

Qishan Liu

Yu-Feng Li

Theory of inverse beta decay for reactor antineutrinos

We present a complete calculation of radiative corrections to the inverse beta decay reaction, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mover accent="true"><mi>ν</mi><mo stretchy="false">¯</mo></mover><mi>e</mi></msub><mo>+</mo><mi>p</mi><mo stretchy="false">→</mo><msup><mi>e</mi><mo>+</mo></msup><mo>+</mo><mi>n</mi></math>, at reactor antineutrino energies using heavy-baryon chiral perturbation theory. Our analysis consistently incorporates quantum electrodynamics, chromodynamics, and electroweak contributions for the first time within this framework. We provide updated, high-precision cross-section predictions with a full error budget and present the positron energy spectrum, including radiative effects. The results are essential for normalizing the reactor antineutrino flux, determining neutrino oscillation parameters with subpercent accuracy, and searching for new physics at nuclear power plants.

Radiative Corrections to Inverse Beta Decay: Precision Analysis for Reactor Neutrinos

We study a dark photon dark matter scenario associated with a gauged <italic>U</italic>(1) <inf><italic>X</italic></inf> symmetry, stabilized by a dark parity that forbids kinetic mixing with the Standard Model. The leading interactions between the dark photon dark matter and the Standard Model arise from dimension-six Higgs-portal operators. In previous work, we found that for the parity-violating operator, the dark matter annihilation process is <italic>p</italic>-wave suppressed, naturally evading stringent direct-detection constraints while reproducing the observed relic abundance through thermal freeze-out. For a cutoff scale of 1&#8201;TeV, a dark matter mass of around 400&#8201;GeV is favored to realize the observed relic abundance. This scenario predicts cosmic-ray signals, in particular in the <math altimg='si15.svg'><mrow><msup><mi>W</mi><mo>+</mo></msup><msup><mi>W</mi><mo>&#8722;</mo></msup></mrow></math> channel, which can be targeted by indirect-detection experiments. Recently, a halo-like gamma-ray excess has been reported by Totani. Assuming a Navarro&#8211;Frenk&#8211;White <math altimg='si16.svg'><mrow><mo>&#8722;</mo><msup><mi>&#961;</mi><mn>2</mn></msup></mrow></math> morphology for the dark matter distribution, a dark matter mass of 420&#8201;GeV is favored for the <math altimg='si15.svg'><mrow><msup><mi>W</mi><mo>+</mo></msup><msup><mi>W</mi><mo>&#8722;</mo></msup></mrow></math> final state. Motivated by this excess, we consider the present dark photon dark matter framework augmented by a CP-even sub-GeV scalar mediator, which couples to the dark photon mass operator in order to enhance the present-day annihilation rate in the Galactic halo while inducing only an <math altimg='si17.svg'><mrow><mi mathvariant='script'>O</mi><mo>(</mo><mn>1</mn><mo>)</mo></mrow></math> correction at freeze-out. The exchange of this scalar induces a long-range attractive force, leading to Sommerfeld enhancement of the annihilation rate. The enhancement is saturating in dwarf spheroidal galaxies and the annihilation rate is dropping as <italic>p</italic>-wave remaining consistent with constraints from dwarf galaxies and cosmology.

Kimiko Yamashita

Higgs-portal spin-1 dark matter with parity-violating interaction for a galactic halo gamma ray excess

The one-state statement for closed universes has sparked considerable discussion. In this paper, we examine its physical meaning in the context of the Hartle-Hawking state and de Sitter space. We argue that the one-state property of closed universes is fully compatible with the finite-dimensional quantum mechanics experienced by observers inside de Sitter space, and that this compatibility requires neither mixing of $\textit{α}$-sectors nor any modification of the rules of the gravitational path integral. The apparent tension is resolved by sharply distinguishing the baby-universe Hilbert space (the space of closed universes viewed from the $\textit{outside}$) from the bulk Hilbert space that governs quantum mechanics for an observer $\textit{inside}$ a single de Sitter universe.

Ying Zhao

“It from Bit”: the Hartle-Hawking state and quantum mechanics for de Sitter observers

Based on <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math> annihilation data collected with the BESIII detector at center-of-mass energies from 4.600 to 4.699 GeV, corresponding to an integrated luminosity of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>4.5</mn><mtext> </mtext><mtext> </mtext><msup><mi>fb</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></math>, we present the first measurement of the longitudinal polarization of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Λ</mi></math> hyperon produced in the inclusive decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi mathvariant="normal">Λ</mi><mi>c</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><mi mathvariant="normal">Λ</mi><mi>X</mi></math>, where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>X</mi></math> denotes any allowed final states. The polarizations are determined to be <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="script">P</mi><mi mathvariant="normal">Λ</mi></msub><mo>=</mo><mo>−</mo><mn>0.393</mn><mo>±</mo><mn>0.05</mn><msub><mn>5</mn><mrow><mi>stat</mi></mrow></msub><mo>±</mo><mn>0.02</mn><msub><mn>0</mn><mrow><mi>syst</mi></mrow></msub></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="script">P</mi><mover accent="true"><mi mathvariant="normal">Λ</mi><mo stretchy="false">¯</mo></mover></msub><mo>=</mo><mn>0.288</mn><mo>±</mo><mn>0.05</mn><msub><mn>6</mn><mrow><mi>stat</mi></mrow></msub><mo>±</mo><mn>0.01</mn><msub><mn>7</mn><mrow><mi>syst</mi></mrow></msub></math>. A search for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math> violation is performed using an asymmetry constructed from the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Λ</mi></math> polarization and the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Λ</mi><mo stretchy="false">→</mo><mi>p</mi><msup><mi>π</mi><mo>−</mo></msup></math> decay asymmetry parameter, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi mathvariant="script">A</mi><mrow><mi>C</mi><mi>P</mi></mrow><mi>pol</mi></msubsup><mo>=</mo><mn>0.15</mn><mo>±</mo><mn>0.1</mn><msub><mn>2</mn><mrow><mi>stat</mi></mrow></msub><mo>±</mo><mn>0.0</mn><msub><mn>3</mn><mrow><mi>syst</mi></mrow></msub></math> was obtained. Furthermore, an updated measurement of the absolute branching fraction is reported as <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">B</mi><mo stretchy="false">(</mo><msubsup><mi mathvariant="normal">Λ</mi><mi>c</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><mi mathvariant="normal">Λ</mi><mi>X</mi><mo stretchy="false">)</mo><mo>=</mo><mo stretchy="false">(</mo><mn>38.07</mn><mo>±</mo><mn>0.3</mn><msub><mn>8</mn><mrow><mi>stat</mi></mrow></msub><mo>±</mo><mn>0.4</mn><msub><mn>9</mn><mrow><mi>syst</mi></mrow></msub><mo stretchy="false">)</mo><mo>%</mo></math>, representing a fourfold precision improvement over the previous BESIII measurement. A search for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math> violation in the decay rate yields <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi mathvariant="script">A</mi><mrow><mi>C</mi><mi>P</mi></mrow><mi>dir</mi></msubsup><mo>=</mo><mo stretchy="false">(</mo><mn>1.5</mn><mo>±</mo><msub><mn>1.0</mn><mrow><mi>stat</mi></mrow></msub><mo>±</mo><msub><mn>1.0</mn><mrow><mi>syst</mi></mrow></msub><mo stretchy="false">)</mo><mo>%</mo></math>. No evidence for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math> violation is observed in this inclusive charm baryon decay. The subscripts ‘stat’ and ‘syst’ denote statistical and systematic uncertainties, respectively.

M. Ablikim

Russia

M.N. Achasov

P. Adlarson

X.C. Ai

C.S. Akondi

R. Aliberti

A. Amoroso

Q. An

Y.H. An

Y. Bai

JINR

O. Bakina

Y. Ban

H.R. Bao

X.L. Bao

V. Batozskaya

Mongolia

K. Begzsuren

N. Berger

M. Berlowski

M.B. Bertani

D. Bettoni

F. Bianchi

E. Bianco

A. Bortone

I. Boyko

R.A. Briere

A. Brueggemann

H. Cai

M.H. Cai

X. Cai

A. Calcaterra

G.F. Cao

N. Cao

S.A. Cetin

Precision Studies and Searches for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math> Asymmetries in the Inclusive Decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi mathvariant="normal">Λ</mi><mi>c</mi><mo>+</mo></msubsup><mo stretchy="false">→</mo><mi mathvariant="normal">Λ</mi><mi>X</mi></math>