A search is presented for hadronic signatures of beyond the Standard Model (BSM) physics, with an emphasis on signatures of a strongly coupled hidden dark sector accessed via resonant production of a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>Z</mi><mo>′</mo></msup></math> mediator. The ATLAS experiment dataset collected at the Large Hadron Collider from 2015 to 2018 is used, consisting of proton-proton collisions 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> and 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>. The <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>Z</mi><mo>′</mo></msup></math> mediator is considered to decay to two dark quarks, which each hadronize and decay to showers containing both dark and Standard Model particles, producing a topology of interacting and noninteracting particles within a jet known as “semivisible.” Machine learning methods are used to select these dark showers and reject the dominant background of mismeasured multijet events, including an anomaly detection approach to preserve broad sensitivity to a variety of BSM topologies. A resonance search is performed by fitting the transverse mass spectrum based on a functional form background estimation. No significant excess over the expected background is observed. Results are presented as limits on the production cross section of semivisible jet signals, parametrized by the fraction of invisible particles in the decay and the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>Z</mi><mo>′</mo></msup></math> mass, and by quantifying the significance of any generic Gaussian-shaped mass peak in the anomaly region.

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

P. Albicocco

G.L. Albouy

S. Alderweireldt

Z.L. Alegria

CERN

M. Aleksa

I.N. Aleksandrov

C. Alexa

Greece

T. Alexopoulos

F. Alfonsi

Switzerland

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

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

F. Anulli

M. Aoki

T. Aoki

Search for new physics in final states with semivisible jets or anomalous signatures using the ATLAS detector

We compute next-to-leading power corrections in the zero-jettiness variable for the production of colorless final states at hadron colliders at next-to-leading order in QCD. To assess if the process-independence of leading power contributions can be extended, we attempt to construct generic expansions of phase spaces and matrix elements squared through next-to-leading power in the zero-jettiness. We highlight challenges associated with the collinear limit, where universality no longer holds at the subleading power, making the result process-dependent. We show that quantities that need to be calculated in the collinear limit can be obtained using Berends-Giele currents, enabling computation of power corrections to high-multiplicity final states. As a concrete example, we apply our method to compute power corrections in the zero-jettiness for lepton pair as well as multi-photon production in $$ q\overline{q} $$ collisions.

Prem Agarwal

Kirill Melnikov

Ivan Pedron

Philip Pfohl

Power corrections to the production of a color-singlet final state in hadron collisions in the $\textit{N}$-jettiness slicing scheme at NLO QCD

An important theoretical achievement of the last century was the realization that strict renormalizability can be a powerful criterion to select Lagrangians in the framework of perturbative quantum field theory. The Standard Model Lagrangian (without gravity) is strictly renormalizable from a perturbative point of view. On the other hand, the inclusion of gravity seems not to respect this criterion, since general relativity is perturbatively non-renormalizable. The aim of this work is to provide concrete evidence that strict renormalizability is still a valid criterion even when applied to gravity. First, we show that adding quadratic curvature terms to the Einstein-Hilbert action gives rise to a strictly renormalizable theory known as quadratic gravity. Second, we argue that this unique theory represents the most conservative approach to quantum gravity and, at the same time, is highly predictive, as it can explain new physics beyond general relativity already in the sub-Planckian regime. In particular, it provides one of the best fits to the CMB anisotropies via Starobinsky inflation and makes sharp cosmological predictions that can be tested in the near future. Finally, we comment on the (super-)Planckian regime and conclude with a historical note.

Netherlands

Luca Buoninfante

Strict renormalizability as a paradigm for fundamental physics

In quantum many-body systems, time-evolved states typically remain confined to a smaller region of the Hilbert space known as the $\textit{Krylov subspace}$. The time evolution can be mapped onto a one-dimensional problem of a particle moving on a chain, where the average position 〈$\textit{n}$〉 defines Krylov state complexity or spread complexity. Generalized spread complexities, associated with higher-order moments 〈$\textit{n}$ 〉 for $\textit{p >}$ 1, provide finer insights into the dynamics. We investigate the time evolution of generalized spread complexities following a quantum quench in random matrix theory. The quench is implemented by transitioning from an initial random Hamiltonian to a post-quench Hamiltonian obtained by dividing it into four blocks and flipping the sign of the off-diagonal blocks. This setup captures universal features of chaotic quantum quenches. When the initial state is the thermofield double state of the post-quench Hamiltonian, a peak in spread complexity preceding equilibration signals level repulsion, a hallmark of quantum chaos. We examine the robustness of this peak for other initial states, such as the ground state or the thermofield double state of the pre-quench Hamiltonian. To quantify this behavior, we introduce a measure based on the peak height relative to the late-time saturation value. In the continuous limit, higher-order complexities show increased sensitivity to the peak, supported by numerical simulations for finite-size random matrices.

South Korea

Hugo Camargo

Yichao Fu

Viktor Jahnke

Keun-Young Kim

Kuntal Pal

Higher-order Krylov state complexity in random matrix quenches

In relativistic heavy-ion collisions, charged particles are accelerated to nearly the speed of light, and their external electromagnetic fields can be effectively approximated as quasireal photons. These photons interact with another nucleus via photon-nuclear interactions, producing vector mesons. These vector mesons possess extremely low transverse momentum (<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msub><mi>p</mi><mi>T</mi></msub><mo>∼</mo><mn>0.1</mn><mspace width="0.16em"></mspace><mi>GeV</mi><mo>/</mo><mi>c</mi></mrow></math>), distinguishing them from particles produced via hadronic interactions. STAR and ALICE have observed <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>J</mi><mo>/</mo><mi>ψ</mi></mrow></math>, <math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mi>ρ</mi><mn>0</mn></msup></math> and other vector mesons with very low <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>p</mi><mi>T</mi></msub></math>, which are well described by photoproduction models. This unique characteristic of having extremely low transverse momentum allows them to serve as a novel experimental probe. Recent STAR results show that the equivalent photons in photoproduction processes are fully linearly polarized, affecting the azimuthal distribution of final-state particles like <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msup><mi>ρ</mi><mn>0</mn></msup><mo>→</mo><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>−</mo></msup></mrow></math>. Since the polarization links to the initial collision geometry, the <math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mi>ρ</mi><mn>0</mn></msup></math> azimuthal modulation can probe nuclear structure. However, the post-collision magnetic field may deflect these particles, distorting the azimuthal distribution and complicating structure measurements. We simulated the distribution of residual magnetic fields over time under different collision conditions using ultrarelativistic quantum molecular dynamics for <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>Au</mi><mo>+</mo><mi>Au</mi></mrow></math> collisions at <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msqrt><msub><mi>s</mi><mi>NN</mi></msub></msqrt><mo>=</mo><mn>200</mn></mrow></math> GeV and calculated their effects on the azimuthal modulation (<math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mo>〈</mo><mo form="prefix">cos</mo><mn>2</mn><mi>ϕ</mi><mo>〉</mo></mrow></math>) of photoproduced <math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mi>ρ</mi><mn>0</mn></msup></math>. Our results show that in peripheral collisions, the field significantly alters the <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mo>〈</mo><mo form="prefix">cos</mo><mn>2</mn><mi>ϕ</mi><mo>〉</mo></mrow></math> for photoproduced <math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mi>ρ</mi><mn>0</mn></msup></math> with <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msub><mi>p</mi><mi>T</mi></msub><mo>≈</mo><mspace width="0.16em"></mspace><mn>0.1</mn></mrow></math> <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>GeV</mi><mo>/</mo><mi>c</mi></mrow></math>. This provides key insights for future nuclear structure studies via photoproduction in peripheral collisions.

Zhan Zhang

Xin Wu

Xinbai Li

Wangmei Zha

Zebo Tang

Influence of the residual magnetic field on the azimuthal distribution of final-state particles in photonuclear processes

The discovery of numerous new hadrons over the past two decades has provided unprecedented opportunities to understand the nonperturbative QCD and hadron structure. The hadronic molecule picture plays an important role in explaining these new hadrons and enriching the configurations of exotic hadronic states. In this Letter, using the model-independent <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi><mi>K</mi></math> potential extracted from the relevant experimental data, a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>J</mi><mrow><mi>P</mi><mi>C</mi></mrow></msup><mo>=</mo><msup><mn>0</mn><mrow><mo>−</mo><mo>−</mo></mrow></msup></math> <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mover accent="true"><mi>D</mi><mo stretchy="false">¯</mo></mover><mi>s</mi></msub><mi>D</mi><mi>K</mi></math> three-body hadronic molecule is predicted with a mass of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msubsup><mrow><mn>4310</mn></mrow><mrow><mo>−</mo><mn>24</mn></mrow><mrow><mo>+</mo><mn>14</mn></mrow></msubsup><mtext> </mtext><mtext> </mtext><mi>MeV</mi></mrow></math>. This state shows decoupling to conventional <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>c</mi><mover accent="true"><mi>c</mi><mo stretchy="false">¯</mo></mover></math> charmonia or the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mover accent="true"><mi>D</mi><mo stretchy="false">¯</mo></mover><mi>s</mi></msub><msubsup><mi>D</mi><mrow><mi>s</mi><mn>0</mn></mrow><mo>*</mo></msubsup><mo stretchy="false">(</mo><mn>2317</mn><mo stretchy="false">)</mo></math> two-body molecular state. It can be regarded as a compelling three-body hadronic molecular candidate. We further demonstrate that the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>B</mi><mo>+</mo></msup><mo stretchy="false">→</mo><msup><mi>D</mi><mrow><mo>*</mo><mo>±</mo></mrow></msup><msup><mi>D</mi><mo>∓</mo></msup><msup><mi>K</mi><mo>+</mo></msup></math> decays could be promising channels for searching for the predicted state in future high-luminosity LHCb runs.

Tian-Wei Wu

Ming-Zhu Liu

Li-Sheng Geng

Implication of the Existence of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>J</mi></mrow><mrow><mi>P</mi><mi>C</mi></mrow></msup><mo>=</mo><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mo>−</mo></mrow></msup><mtext> </mtext><msub><mrow><mover accent="true"><mrow><mi>D</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover></mrow><mrow><mi>s</mi></mrow></msub><mi>D</mi><mi>K</mi></mrow></math> Bound State on the Nature of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msubsup><mrow><mi>D</mi></mrow><mrow><mi>s</mi><mn>0</mn></mrow><mrow><mo>*</mo></mrow></msubsup><mo stretchy="false">(</mo><mn>2317</mn><mo stretchy="false">)</mo></mrow></math>, and a New Configuration of Exotic State

A measurement of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mrow><mi>W</mi></mrow><mi>Z</mi><mi>γ</mi></mrow></math> triboson production cross section is presented. The analysis is based on a data sample of proton-proton collisions at a center-of-mass energy of <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> recorded with the CMS detector at the LHC, corresponding to an integrated luminosity of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>138</mn><mtext> </mtext><mtext> </mtext><msup><mi>fb</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></math>. The analysis focuses on the final state with three charged leptons, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mrow><msup><mrow><mo>ℓ</mo></mrow><mrow><mo>±</mo></mrow></msup></mrow><mi>ν</mi><mrow><msup><mrow><mo>ℓ</mo></mrow><mrow><mo>+</mo></mrow></msup></mrow><mrow><msup><mrow><mo>ℓ</mo></mrow><mrow><mo>−</mo></mrow></msup></mrow></mrow></math>, where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo>ℓ</mo><mo>=</mo><mi>e</mi></math> or <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>μ</mi></mrow></math>, accompanied by an additional photon. The observed (expected) significance of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>W</mi></mrow><mi>Z</mi><mrow><mi>γ</mi></mrow></math> signal is 5.4 (3.8) standard deviations. The cross section is measured in a fiducial region, where events with an ℓ originating from a tau lepton decay are excluded, to be <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>5.48</mn><mo>±</mo><mn>1.11</mn><mtext> </mtext><mtext> </mtext><mi>fb</mi></math>, which is compatible with the prediction of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>3.69</mn><mo>±</mo><mn>0.24</mn><mtext> </mtext><mtext> </mtext><mi>fb</mi></math> at next-to-leading order in quantum chromodynamics. Exclusion limits are set on anomalous quartic gauge couplings and on the production cross sections of massive axionlike particles.

Armenia

V. Chekhovsky

A. Hayrapetyan

V. Makarenko

A. Tumasyan

Austria

W. Adam

J.W. Andrejkovic

L. Benato

T. Bergauer

S. Chatterjee

K. Damanakis

M. Dragicevic

P.S. Hussain

M. Jeitler

N. Krammer

A. Li

D. Liko

I. Mikulec

J. Schieck

R. Schöfbeck

D. Schwarz

M. Sonawane

W. Waltenberger

C.E. Wulz

Belgium

T. Janssen

H. Kwon

T. Van Laer

P. Van Mechelen

N. Breugelmans

J. D’Hondt

S. Dansana

A. De Moor

M. Delcourt

F. Heyen

Y. Hong

S. Lowette

I. Makarenko

D. Müller

S. Tavernier

M. Tytgat

G.P. Van Onsem

Observation of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>W</mi><mi>Z</mi><mi>γ</mi></math> production and constraints on new physics scenarios in proton-proton collisions 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>