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.

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

South Africa

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

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.

N. Abicht

S. Abidi

B. Acharya

S. Addepalli

M. Addison

A. Affolder

M. Agaras

Azerbaijan

T. Åkesson

A. Akimov

N. Akolkar

G. Alberghi

G. Albouy

Z. Alegria

I. Aleksandrov

Saudi Arabia

H. Ali

S. Alibocus

B. Allbrooke

J. Allen

P. Allport

Z. Alsolami

M. Alviggi

C. Ames

S. Amor Dos Santos

K. Amos

J. Anders

A. Anderson

A. Anisenkov

F. Anulli

M. Aoki

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

Australia

C.S. Alley

E.R. Almazan

T. Aoki

M.A. Aparo

L. Aperio Bella

M. Apicella

C. Appelt

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

The production of single top quarks and top antiquarks via the $\textit{t}$-channel exchange of a virtual $\textit{W}$ boson is measured in proton-proton collisions at a centre-of-mass energy of 13 TeV at the Large Hadron Collider. The full Run 2 data sample recorded with the ATLAS detector in the years 2015–2018 is used, corresponding to an integrated luminosity of 140 fb . The absolute and normalised production cross-sections are measured differentially as a function of the transverse momentum and absolute rapidity of the top quark and top antiquark. In addition, the ratio of top quark to top antiquark production cross-sections is measured. The measured distributions are compared with next-to-leading-order quantum chromodynamics predictions obtained with different combinations of matrix-element generators, parton-shower programs and proton parton distribution functions, as well as to next-to-next-to-leading-order calculations. Overall, good agreement is observed between the measurements and the theoretical predictions. For most measured distributions, the sensitivity to differences between the predictions is limited by the systematic uncertainties in the measurement. The measured differential distributions are also interpreted in an effective field theory approach to constrain the Wilson-Coefficient $$ {C}_{Qq}^{3,1} $$ associated with a four-quark operator. The interpretation accounts for the effect of the selection efficiency, which is altered significantly by non-zero contributions from $$ {C}_{Qq}^{3,1} $$ .

D. Allen

Measurement of differential $\textit{t}$-channel single top (anti)quark production cross-sections at 13 TeV with the ATLAS detector

A measurement of the associated production of a top-quark pair with the Higgs boson ( $$ t\overline{t}H $$ ) in multilepton final states is presented. The analysis is based on a data sample of proton-proton collisions at $$ \sqrt{s}=13 $$ TeV recorded with the ATLAS detector at the CERN Large Hadron Collider and corresponding to an integrated luminosity of 140 fb . Six final states defined by the number and flavour of reconstructed charged leptons are combined in a simultaneous likelihood fit to extract the $$ t\overline{t}H $$ signal and constrain the most relevant backgrounds. The measured $$ t\overline{t}H $$ cross-section normalised to Standard Model (SM) prediction is $$ {\sigma}_{t\overline{t}H}/{\sigma}^{\mathrm{SM}}=0.{63}_{-0.19}^{+0.20} $$ . This result corresponds to an observed (expected) significance of 3.3$\textit{σ}$ (5.3$\textit{σ}$). Additionally, two other fits are used to measure the $$ t\overline{t}H $$ cross-section differentially in bins of the Higgs boson transverse momentum in the simplified template cross-section framework, and to extract the associated production cross-section of a single top-quark with the Higgs boson ($\textit{tH}$) together with the $$ t\overline{t}H $$ one. The $\textit{CP}$ structure of the top quark-Higgs boson Yukawa coupling is probed through an analysis of $$ t\overline{t}H $$ and $\textit{tH}$ events. The results are compatible with the SM hypothesis, and values of the mixing angle between $\textit{CP}$-even and $\textit{CP}$-odd top-Higgs Yukawa couplings of |$\textit{α}$| $\textit{>}$ 62 are excluded at 68% confidence level.

M. Aparo

Measurement of the Higgs boson production in association with top quarks in multilepton final states in $\textit{pp}$ collisions at $$ \sqrt{s}=13 $$ TeV with the ATLAS detector

The novel proposal to invoke the split of the Ricci scalar into bulk and boundary terms in the gravitational action, opens up a new avenue of investigation into stellar dynamics. The Lagrangian contains functional forms of the bulk term while the boundary term do not contribute to the dynamics. The advantage of the proposition is that the stellar structure equations are up to order two, thus the theory is not haunted by ghosts. We obtain explicitly the defining equations for the thermodynamical variables and the geometry for the pure quadratic case, since the linear case amounts to general relativity. In trying to establish the vacuum geometry associated with the theory it turns out that two possible metrics emerge through the vanishing of the energy-momentum tensor. Next, we analyse the isotropy equation and make the observation that it is autonomous. It is rare that this happens in astrophysical modelling. This behaviour prompted the use of dynamical systems to understand the stability properties of fixed points or invariant submanifolds. It was necessary to choose a gauge in order to split the autonomous equation into a system from which we could plot a phase portrait and deduce the stability of solution trajectories. We find that the invariant submanifolds were generally stable with nearby paths approaching them.

Sudan Hansraj

Christian Boehmer

Ndumiso Buthelezi

Dynamical systems approach to stellar modelling in $\textit{f}$($\textit{G}$, $\textit{B}$) gravity

We present quantitative results on the single-mass heavy-flavor contributions in the region of large virtualities <italic>Q</italic> 2 up to three-loop order to the unpolarized structure function <italic>F</italic> <inf>2</inf>( <italic>x, Q</italic> 2) and the polarized structure function <italic>g</italic> <inf>1</inf>( <italic>x, Q</italic> 2) for the first time. These results are relevant for precision QCD analyses of the World deep-inelastic data and the data taken at future colliders, such as the Electron&#8211;Ion Collider, since the scaling violations due to massless and massive Wilson coefficients are significantly different. In order to measure the strong coupling constant <math altimg='si19.svg'><mrow><msub><mi>&#945;</mi><mi>s</mi></msub><mrow><mo>(</mo><msubsup><mi>M</mi><mi>Z</mi><mn>2</mn></msubsup><mo>)</mo></mrow></mrow></math> and the twist-2 parton distribution functions consistently at highest precision, the next-to-next-to-leading order corrections have to be taken into account. We also provide a fast and precise public numerical code for the unpolarized and polarized massive Wilson coefficients in the asymptotic region.

The three-loop single-mass heavy-flavor corrections to the structure functions <italic>F</italic> <inf>2</inf>( <italic>x, Q</italic> 2) and <italic>g</italic> <inf>1</inf>( <italic>x, Q</italic> 2)