In this article, we present projected 95% C.L. limits on axion-like particle (ALP) couplings from ALP production at a future $$e^+e^-$$ collider operating at $$\sqrt{s} = 250~\text {GeV}$$ with integrated luminosity $$L = 0.5~\text {ab}^{-1}$$ . We constrain the effective couplings $$g_{\gamma \gamma }$$ , $$g_{Z\gamma }$$ , $$g_{ZZ}$$ , and $$g_{WW}$$ over the ALP mass range $$20~\text {GeV} \le m_a \le 100~\text {GeV}$$ , finding projected bounds at the level of $$\mathcal {O}(10^{-1})~\text {TeV}^{-1}$$ for $$g_{\gamma \gamma }/f_a$$ . Given that the latest muon anomalous magnetic moment measurement ( $$\Delta a_\mu $$ ) shows no statistically significant deviation from the Standard Model prediction, we reinterpret the ALP contributions to $$\Delta a_\mu $$ as a stringent consistency requirement. We then derive the corresponding allowed regions for $$g_{\gamma \gamma }$$ and the ALP–muon coupling $$C_{\mu \mu }$$ , and apply them to a fermionic dark matter scenario in which the relic density depends on both the dark matter mass $$m_\chi $$ and $$m_a$$ . The same parameter space is further constrained by Higgs signal strength measurements through $$h \rightarrow \gamma \gamma $$ and $$h \rightarrow Z\gamma $$ . A comparative analysis with existing experimental and theoretical bounds highlights the complementarity of $$\Delta a_\mu $$ , dark matter, and Higgs observables in restricting ALP couplings, demonstrating that even in the absence of a $$\Delta a_\mu $$ anomaly, these constraints provide essential guidance for viable ALP parameter space.

South Africa

India

Pramod Sharma

Soham Singh

Mukesh Kumar

Ashok Goyal

Comprehensive constraints on ALP couplings from future $$e^+e^-$$ colliders, muon $$g-2$$ , thermal dark matter and Higgs measurements

<p>A search for resonant structures in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>J</mi><mo>/</mo><mi>ψ</mi><mo>+</mo><mi>ψ</mi><mo stretchy="false">(</mo><mn>2</mn><mi mathvariant="normal">S</mi><mo stretchy="false">)</mo></mrow></math> mass spectrum is performed using proton-proton collision data 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>, corresponding to an integrated luminosity of <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>, recorded by the ATLAS experiment at the LHC. The decay channels of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi><mo>+</mo><mi>ψ</mi><mrow><mo stretchy="false">(</mo><mn>2</mn><mi mathvariant="normal">S</mi><mo stretchy="false">)</mo></mrow><mo stretchy="false">→</mo><mn>4</mn><mi>μ</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi><mo>+</mo><mi>ψ</mi><mrow><mo stretchy="false">(</mo><mn>2</mn><mi mathvariant="normal">S</mi><mo stretchy="false">)</mo></mrow><mo stretchy="false">→</mo><mn>4</mn><mi>μ</mi><mo>+</mo><mn>2</mn><mi>π</mi></math> are analyzed. An excess near 6.9 GeV is observed in both channels with a combined significance of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>8.9</mn><mi>σ</mi></mrow></math>. No significant signal is observed near 7.2 GeV, and an upper limit on its yield relative to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>X</mi><mo stretchy="false">(</mo><mn>6900</mn><mo stretchy="false">)</mo></math> is provided. A simultaneous fit with the di-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi></math> channel is carried out under assumptions regarding the resonance interferences, yielding a ratio of the partial decay widths between the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi><mo>+</mo><mi>ψ</mi><mrow><mo stretchy="false">(</mo><mn>2</mn><mi mathvariant="normal">S</mi><mo stretchy="false">)</mo></mrow></math> and di-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi></math> channels of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>1.08</mn><mo>±</mo><mn>0.2</mn><msubsup><mn>0</mn><mrow><mo>−</mo><mn>0.17</mn></mrow><mrow><mo>+</mo><mn>0.40</mn></mrow></msubsup></math> for the resonance near 6.9 GeV.</p>

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

Y. Abulaiti

Italy

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

F. Ahmadov

S. Ahuja

China

X. Ai

G. Aielli

A. Aikot

M. Ait Tamlihat

B. Aitbenchikh

M. Akbiyik

Sweden

T.P.A. Åkesson

A.V. Akimov

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

M. Aliev

G. Alimonti

W. Alkakhi

C. Allaire

B.M.M. Allbrooke

D.R. Allen

J.S. Allen

J.F. Allen

P.P. Allport

A. Aloisio

Argentina

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

C.G. Ames

T. Amezza

D. Amidei

B. Amini

K. Amirie

A. Amirkhanov

Portugal

S.P. Amor Dos Santos

K.R. Amos

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

Observation of structures in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>J</mi><mo>/</mo><mi>ψ</mi><mo>+</mo><mi>ψ</mi><mo stretchy="false">(</mo><mn>2</mn><mi>S</mi><mo stretchy="false">)</mo></math> mass spectrum with the ATLAS detector

A model-independent search for low-mass resonances decaying into pairs of oppositely charged muons is presented. The analysis uses proton-proton collision data corresponding to an integrated luminosity of 140 fb , recorded by the ATLAS detector at the Large Hadron Collider between 2015 and 2018. The search targets hypothetical dimuon resonances in the invariant mass range from 35 GeV to 75 GeV. The modelling of this mass region is particularly challenging for conventional analytic background parameterisations. To address this, a Gaussian process regression technique is used to model the background. The dimuon mass spectrum is analysed for potential signals, and no statistically significant excess is observed. Upper limits at the 95% confidence level are set on the fiducial production cross-section of new resonances decaying promptly into muons, ranging from 20 fb to 110 fb, depending on the resonance mass. These results are further interpreted in the context of dark-photon and dark-matter-mediator models, leading to new constraints on their parameter spaces.

N. Abicht

S. Abidi

B. Acharya

S. Addepalli

M. Addison

A. Affolder

M. Agaras

Azerbaijan

T. Åkesson

N. Akolkar

G. Alberghi

G. Albouy

Z. Alegria

I. Aleksandrov

Saudi Arabia

H. Ali

S. Alibocus

B. Allbrooke

D. Allen

J. Allen

Australia

C. Alley

Z. Alsolami

M. Alviggi

S. Amor Dos Santos

J. Anders

A. Anderson

A. Anisenkov

F. Anulli

M. Aoki

T. Aoki

M. Aparo

L. Aperio Bella

M. Apicella

C. Appelt

Search for dimuon resonance in the 35 to 75 GeV mass range using 140 fb $\textit{−}$1 of 13 TeV $\textit{pp}$ collisions with the ATLAS detector

This paper presents two searches for the electroweak production of higgsinos with compressed mass spectra using 140 fb of $$ \sqrt{s}=13 $$ TeV proton-proton collision data collected by the ATLAS experiment at the Large Hadron Collider. Events are required to feature an energetic jet, large missing transverse momentum, and at least one low-momentum charged particle that serves as a candidate higgsino decay product. In the first search, targeting higgsino mass splittings in the range of 0.3–1 GeV, the higgsinos are expected to predominantly decay into pions that are identified as low-momentum charged particles with large transverse impact parameters due to the long higgsino lifetime ($\textit{cτ}$ ≈ 𝒪(0$\textit{.}$1–10 mm)), and neural networks are used to discriminate between signal and background processes. The second search targets larger mass splittings in the range of 1–3 GeV, where the higgsinos are expected to decay promptly into low-momentum leptons, one of which is identified by dedicated low-momentum electron or muon taggers based on neural networks utilising tracking and calorimeter information. No significant excess above the Standard Model prediction is observed in either search and the results are interpreted within simplified models, to set lower limits on the masses of the higgsino-like charginos and neutralinos. Together, these searches exclude chargino masses below 126 GeV at 95% confidence level for mass splittings between the chargino and lightest neutralino in the range of 0.3–2 GeV. This represents the first ATLAS constraints in a portion of this parameter space and surpasses the limits previously set by other experiments.

A. Akimov

P. Allport

C. Ames

K. Amos

Search for higgsinos in compressed mass spectra using low-momentum tracks in $\textit{pp}$ collisions at $$ \sqrt{s}=13 $$ TeV with the ATLAS detector

A numerical framework for approximating G <inf>2</inf>-structure 3-forms on contact Calabi&#8211;Yau manifolds is presented. The approach proceeds in three stages: first, existing neural network models are employed to compute an approximate Ricci-flat metric on a Calabi&#8211;Yau threefold. Second, using this metric and the explicit construction of a G <inf>2</inf>-structure on the associated 7-dimensional Calabi&#8211;Yau link in the 9-sphere, numerical approximations of the 3-form are generated on a large set of sampled points. Finally, a dedicated neural architecture is trained to learn the 3-form and its induced Riemannian metric directly from data, validating the learned structure and its torsion via a numerical implementation of the exterior derivative, which may be of independent interest.

Elli Heyes

Edward Hirst

Henrique N. Sá Earp

Tomás S.R. Silva

Neural and numerical methods for G <inf>2</inf>-structures on contact Calabi&#8211;Yau 7&#8211;manifolds

We explore 3d $$ \mathcal{N} $$ = 4 theories arising from twisted compactification of 4d $$ \mathcal{N} $$ = 2 ($\textit{G}$, $\textit{G}$ ) Argyres-Douglas superconformal field theories (SCFTs), together with the 2d vertex operator algebras (VOAs) supported on the holomorphic boundary of their topologically twisted sector. Starting from the Coulomb branch BPS spectra of the ($\textit{G}$, $\textit{G}$ ) Argyres-Douglas theories, we develop a systematic and efficient method to obtain the ellipsoid partition functions of associated 3d theories using quiver mutations and wall-crossing invariants. This allows us to extract the modular data of the boundary VOAs, which are related to the Schur sectors of the 4d theories through the 4d SCFT/2d VOA correspondence. Our results provide a useful computational bridge between 4d SCFTs and 2d VOAs through interpolating 3d topological field theories.

South Korea

Minsung Kim

Sungjoon Kim

3D TFTs and boundary VOAs from BPS spectra of ($\textit{G}$, $\textit{G}$ ′) Argyres-Douglas theories

A modified gravitational model whose action is given by an arbitrary function of the Ricci scalar, the matter Lagrangian density, a scalar field, and its kinetic term is investigated as an extension of the gravitational sector including an additional dynamical degree of freedom. Within this framework, the causal structure of rotating cosmological solutions is analyzed by considering Gödel and Gödel-type spacetimes as background geometries used as theoretical probes of the model consistency. Different matter sources are examined, including a perfect fluid and scalar-field configurations. It is found that the standard Gödel metric is not compatible with the scalar sector of the theory unless the model reduces to the General Relativity limit. In contrast, Gödel-type geometries admit a wider class of solutions whose causal properties depend on the model parameters and on the matter content. In particular, perfect-fluid sources may lead to either causal or noncausal configurations, whereas scalar-field configurations constrain the geometry to the causal limit, preventing the formation of closed timelike curves, highlighting that the scalar field plays a nontrivial dynamical role distinct from that of a cosmological constant.

L. Evangelista

M. Silva

J. Moretti

A. Santos

Causality and its violation in $$f(R,\mathcal {L}_m,\phi ,g^{\mu \nu }\nabla _\mu \phi \nabla _\nu \phi )$$ gravity

A search is presented for massive long-lived particles in events featuring at least one displaced vertex and at least one displaced muon, using proton–proton collision data collected by the ATLAS detector at the Large Hadron Collider from 2022 to 2024 at a centre-of-mass energy of 13.6 TeV. The data sample corresponds to an integrated luminosity of 164 fb <math altimg='si22.svg'><msup><mrow /><mrow><mo>&#8722;</mo><mn>1</mn></mrow></msup></math>. The analysis targets scenarios in which long-lived particles decay inside the ATLAS inner detector, resulting in a topology of at least one massive, displaced vertex (DV) with multiple associated tracks, and at least one muon with a large transverse impact parameter relative to the primary interaction point. The muon is not required to be associated with the DV. Two signal regions are defined by the transverse distance of the reconstructed DV from the interaction point. Background contributions are estimated by using fully data-driven techniques. No significant excess above the expected background is observed. Upper limits at 95% confidence level are set on the visible cross-section and on the production cross-sections of several benchmark models of <italic>R</italic>-parity-violating supersymmetry.

A. Ahmad

C.S. Alley

E.R. Almazan

M.A. Aparo

A. Apyan

M. Arampatzi

Search for massive, long-lived particles in events with displaced vertices and displaced muons in <italic>pp</italic> collisions at <math altimg='si21.svg'><mrow><msqrt><mi>s</mi></msqrt><mo linebreak='goodbreak'>=</mo><mn>13.6</mn></mrow></math> TeV with the ATLAS experiment