In this work, a charged fluid system is studied by employing the complexity factor formalism for a static spherical spacetime. We proceed by calculating two distinct mass functions and obtaining the Einstein field equations for the anisotropic fluid. Following Herrera’s methodology, we designate $${Y}_{TF}$$ as the complexity factor as it integrates the two fundamental dynamic components like the density inhomogeneity and pressure anisotropy. Additionally, the field equations are addressed by applying a few constraints, with the first being the condition of zero complexity. By implementing two distinct forms for the radial metric potential, we derive two independent solutions. The unknowns involved in these models are then found using the junction conditions by taking into account the Reissner–Nordström exterior metric. Subsequently, observed data from multiple stars is used to generate a visual depiction of the obtained solutions. Our analysis demonstrates that both proposed models maintain physically stable and viable profiles, highlighting the critical role of the vanishing complexity condition in constructing anisotropic fluid solutions under the presence of an electric charge.

Pakistan

Azerbaijan

Tayyab Naseer

M. Sharif

Javeria Javid

Saudi Arabia

Jordan

Kottakkaran Nisar

Mohammed Zakarya

Orthogonal splitting of the Riemann curvature tensor and implications of resulting scalar(s) on compact stellar evolution

A model-agnostic search for Beyond the Standard Model physics is presented, targeting final states with at least four light leptons (electrons or muons). The search regions are separated by event topology and unsupervised machine learning is used to identify anomalous events in the full 140 fb $$^{-1}$$ of proton–proton collision data collected with the ATLAS detector during Run 2. No significant excess above the Standard Model background expectation is observed. Model-agnostic limits are presented in each topology, along with limits on several benchmark models including vector-like leptons, wino-like charginos and neutralinos, or smuons. Limits are set on the flavourful vector-like lepton model for the first time.

France

G. Aad

Norway

E. Aakvaag

United States

B. Abbott

United Arab Emirates

S. Abdelhameed

Germany

K. Abeling

N. Abicht

S. Abidi

M. Aboelela

Morocco

A. Aboulhorma

Israel

H. Abramowicz

Y. Abulaiti

Italy

United Kingdom

B. Acharya

A. Ackermann

C. Adam Bourdarios

Poland

L. Adamczyk

S. Addepalli

M. Addison

J. Adelman

Türkiye

A. Adiguzel

T. Adye

A. Affolder

Y. Afik

Spain

M. 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. Åkesson

A. Akimov

Japan

D. Akiyama

N. Akolkar

S. Aktas

G. Alberghi

Canada

J. Albert

Switzerland

U. Alberti

P. Albicocco

G. Albouy

S. Alderweireldt

Z. Alegria

M. Aleksa

I. Aleksandrov

C. Alexa

Greece

T. Alexopoulos

F. Alfonsi

M. Algren

M. Alhroob

Czechia

B. Ali

H. Ali

S. Ali

S. Alibocus

South Africa

M. Aliev

G. Alimonti

W. Alkakhi

C. Allaire

B. Allbrooke

D. Allen

J. Allen

P. Allport

A. Aloisio

Argentina

F. Alonso

C. Alpigiani

Z. Alsolami

A. Alvarez Fernandez

M. Alves Cardoso

M. Alviggi

M. Aly

Brazil

Y. Amaral Coutinho

A. Ambler

C. Amelung

M. Amerl

C. Ames

T. Amezza

D. Amidei

B. Amini

K. Amirie

A. Amirkhanov

Portugal

S. Amor Dos Santos

K. Amos

D. Amperiadou

S. An

C. Anastopoulos

T. Andeen

J. Anders

A. Anderson

A. Andreazza

S. Angelidakis

A. Angerami

A. Anisenkov

A. Annovi

C. Antel

E. Antipov

M. Antonelli

Search for Beyond the Standard Model physics with anomaly detection in multilepton final states in $\textit{pp}$ collisions at $$\sqrt{s}=13~\textrm{TeV}$$ with the ATLAS detector

We propose an $$ \mathcal{N}=2 $$ preserving deformation that leads to the confining phase of the 3d reduction of the $\textit{D}$ [SU($\textit{N}$)] Argyres-Douglas theories, referred to as 𝔻 [SU($\textit{N}$)]. This deformation incorporates monopole superpotential terms, which have recently played interesting roles in exploring possible RG fixed points of 3d supersymmetric gauge theories. Employing this confining phenomenon in 3d 𝔻 [SU($\textit{N}$)] theories, we also propose a deconfined version of the Kim-Park duality, an IR duality for 3d $$ \mathcal{N}=2 $$ adjoint SQCDs, where an adjoint matter field is replaced by a linear quiver tail of 𝔻 [SU($\textit{N}$)]. Surprisingly, both the confinement of deformed 𝔻 [SU($\textit{N}$)] and the deconfined Kim-Park duality can be proven only assuming some basic 3d $$ \mathcal{N}=2 $$ IR dualities. Finally, we propose a variant of the Kim-Park duality deformed by a single monopole superpotential term, which can also be derived using the same method.

Chiung Hwang

South Korea

Sungjoon Kim

S-confinement of 3d Argyres-Douglas theories and the Seiberg-like duality with an adjoint matter

The decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>A</mi><mo stretchy="false">→</mo><mi>Z</mi><mi>H</mi></math> is a characteristic signal of two-Higgs-doublet models (2HDMs), where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>A</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>H</mi></math> lie primarily within the same <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>S</mi><mi>U</mi><mo stretchy="false">(</mo><mn>2</mn><msub><mo stretchy="false">)</mo><mi>L</mi></msub></math> multiplet, leading to a coupling of order <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>g</mi><mn>2</mn></msub></math> to the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Z</mi></math> boson. The subsequent decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>H</mi><mo stretchy="false">→</mo><mi>t</mi><msup><mi>t</mi><mrow><mo stretchy="false">(</mo><mo>*</mo><mo stretchy="false">)</mo></mrow></msup></math> is particularly promising, as it gives rise to distinct final states involving multiple leptons and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>b</mi></math>-jets. The required splitting between <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mi>A</mi></msub></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mi>H</mi></msub></math> can naturally occur near the electroweak scale while being consistent with perturbative unitarity. Whereas dedicated ATLAS and CMS searches focused on the region with both top-quarks on-shell, we cover lower masses where one top quark is off-shell by recasting Standard Model <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>t</mi><mover accent="true"><mi>t</mi><mo stretchy="false">¯</mo></mover><mi>Z</mi></math> measurements of ATLAS and CMS. The obtained limits on <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>σ</mi><mo stretchy="false">(</mo><mi>A</mi><mo stretchy="false">→</mo><mi>Z</mi><mi>H</mi><mo stretchy="false">)</mo><mo>×</mo><mi>Br</mi><mo stretchy="false">(</mo><mi>H</mi><mo stretchy="false">→</mo><mi>t</mi><mover accent="true"><mi>t</mi><mo stretchy="false">¯</mo></mover><mo stretchy="false">)</mo></math> are between 0.12 pb and 0.62 pb. Interestingly, we observe these stringent limits despite a preference (up to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>2.5</mn><mi>σ</mi></math>) for a nonzero new physics signal, most pronounced around for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>m</mi></mrow><mrow><mi>A</mi></mrow></msub><mo>≈</mo><mn>450</mn><mi>–</mi><mn>460</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mi>H</mi></msub><mo>≈</mo><mn>290</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math>, with a best-fit value of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>σ</mi><mo stretchy="false">(</mo><mi>A</mi><mo stretchy="false">→</mo><mi>Z</mi><mi>H</mi><mo stretchy="false">)</mo><mo>×</mo><mi>Br</mi><mo stretchy="false">(</mo><mi>H</mi><mo stretchy="false">→</mo><mi>t</mi><mover accent="true"><mi>t</mi><mo stretchy="false">¯</mo></mover><mo stretchy="false">)</mo><mo>≈</mo><mn>0.3</mn><mtext> </mtext><mtext> </mtext><mi>pb</mi></math>. This cross section can be accommodated within a top-philic 2HDM for a top-Yukawa coupling of the second Higgs doublet of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>0.16</mn><mo>≲</mo><msub><mi>μ</mi><mi>t</mi></msub><mo>≲</mo><mn>0.33</mn></math>.

Saiyad Ashanujjaman

Guglielmo Coloretti

Andreas Crivellin

India

Siddharth P. Maharathy

Bruce Mellado

Constraining <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>A</mi><mo stretchy="false">→</mo><mi>Z</mi><mi>H</mi></math> with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>H</mi><mo stretchy="false">→</mo><mi>t</mi><mover accent="true"><mi>t</mi><mo stretchy="false">¯</mo></mover></math> in the low-mass region

We construct an explicit basis set for pentaquark states on a regular 4-simplex, that diagonalizes the Hamiltonian for light pentaquarks with confinement on the light front (LF). The ensuing eigenstates are free of the center of mass motion and satisfy exact Dirichlet boundary conditions. Hyperfine interactions in the form of color-spin or flavor-spin are shown to lift the degeneracy of the 16 pentastates, with a spectrum that compares fairly with some of the empirical nucleon excited states. The quark PDF for the light pentastates is discussed.

Fangcheng He

Edward Shuryak

Wan Wu

Ismail Zahed

Light <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>S</mi></math>-wave pentaquarks on the light front

Understanding the source of the universe’s asymmetry between matter and antimatter is one of the major open questions in particle physics. In this work, the sensitivity of novel machine-learning-based inference techniques to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math>-odd and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math>-even <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>H</mi><mi>W</mi><mi>W</mi></math> anomalous couplings is studied in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>W</mi><mi>H</mi><mo stretchy="false">→</mo><mo>ℓ</mo><mi>ν</mi><mi>b</mi><mover accent="true"><mi>b</mi><mo stretchy="false">¯</mo></mover></math> channel (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo>ℓ</mo><mo>=</mo><mi>e</mi><mo>,</mo><mrow><mi>μ</mi></mrow></mrow></math>), within the standard model effective field theory framework. Two machine-learning simulation-based inference (SBI) methods are explored: a per-event likelihood-ratio estimator, which directly approximates the ratio of probability densities between competing hypotheses, is benchmarked against a per-event optimal-observable estimator optimized for sensitivity to the parameters of interest. Both approaches are also compared to traditional summary statistics, in this case histograms of kinematic and angular observables, as commonly used in experimental analyses. SBI methods provide tighter constraints than one-dimensional summary statistics, though their performance is comparable to two-dimensional histogram analysis. The optimal-observable approach remains promising for its ability to probe multiple couplings simultaneously. Restricting the analysis to a region of high <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>S</mi><mo>/</mo><mi>B</mi></math> also enhances sensitivity to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math>-odd operators while preserving sensitivity to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math>-even operators, which histogram analyses often lose. Although the likelihood-ratio estimator sometimes struggles with likelihood minima and shapes, optimizations that target its robustness could make it more sensitive than both the optimal-observable estimator and the histogram method. These results underscore the potential of advanced simulation-based inference techniques, encouraging further exploration with LHC Run 3 data to surpass current ATLAS and CMS sensitivities.

Marta Silva

Ricardo Barrué

Inês Ochoa

Patricia Conde Muíño

Searching for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>H</mi><mi>W</mi><mi>W</mi></math> anomalous couplings with simulation-based inference

A potential quark model is used to search for a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msubsup><mrow><mi>P</mi></mrow><mrow><mi>c</mi><mover accent="true"><mrow><mi>c</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover><mi>s</mi></mrow><mrow><mn>0</mn></mrow></msubsup><mo>=</mo><mo stretchy="false">(</mo><mi>c</mi><mover accent="true"><mrow><mi>c</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover><mi>u</mi><mi>d</mi><mi>s</mi><msup><mrow><mo stretchy="false">)</mo></mrow><mrow><mn>0</mn></mrow></msup></mrow></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>J</mi><mi>P</mi></msup><mo>=</mo><mn>1</mn><mo>/</mo><msup><mn>2</mn><mo>−</mo></msup></math> pentaquark state that has recently been observed experimentally by LHCb Collaboration at 4338.2 MeV, with a width of 7.0 MeV and high statistical significance <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo form="prefix">&gt;</mo><mn>15</mn><mi>σ</mi></math>. Our model Hamiltonian reproduces the masses of the low-lying charmed and strange hadrons. We use the Gaussian expansion method to solve the five-body Schrödinger equation. Employing the real scaling method, including the relevant meson-baryon thresholds explicitly, sharp resonances are distinguished from the meson-baryon scattering states. We incorporate new color states of the color-octet meson and baryon configurations as well as the color-singlet configurations for the five-quark states. We find no <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>J</mi><mi>P</mi></msup><mo>=</mo><mn>1</mn><mo>/</mo><msup><mn>2</mn><mo>−</mo></msup></math> resonance close to the observed state, and also none in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>J</mi><mi>P</mi></msup><mo>=</mo><mn>3</mn><mo>/</mo><msup><mn>2</mn><mo>−</mo></msup></math> state. This increases the likelihood that <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>P</mi><mrow><mi>c</mi><mover accent="true"><mi>c</mi><mo stretchy="false">¯</mo></mover><mi>s</mi></mrow><mn>0</mn></msubsup></math> is a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="normal">Ξ</mi><mi>c</mi></msub><mover accent="true"><mi>D</mi><mo stretchy="false">¯</mo></mover></math> hadronic molecule rather than a compact state.

Emiko Hiyama

Atsushi Hosaka

Makoto Oka

Georg Wolschin

Quark-model search for compact <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>c</mi><mover accent="true"><mrow><mi>c</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover><mi>u</mi><mi>d</mi><mi>s</mi></mrow></math> pentaquark states

In (2 +1)-dimensional topological quantum field theories (TQFTs), the action of a global symmetry group on the anyon system is one of the central topics of research. Owing to the subtle categorical nature of anyons, a global symmetry acting on them is generally realized in a projective manner. Symmetry fractionalization encodes this projective realization. The obstruction to defining symmetry fractionalization is captured by a cohomology class, known as the $\textit{H}$ obstruction, whose nontriviality signals a failure to define symmetry fractionalization consistently. In this short note, we prove that the $\textit{H}$ obstruction for time-reversal symmetry always vanishes in abelian bosonic TQFTs.

Ippo Orii

Vanishing of the $\textit{H}$

We investigate charge-balance functions for pion, kaon, and proton pairs in proton-proton (pp) collisions at <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msqrt><mi>s</mi></msqrt><mo>=</mo><mn>13</mn></mrow></math> TeV using Monte Carlo models, pythia8, and epos-lhc, with transverse spherocity to classify event topology and charged-particle multiplicity to select system size. Simulations with pythia8 and epos-lhc reveal that balance-function widths in rapidity and azimuthal angle depend on multiplicity and event shape. In pythia8, widths decrease monotonically with multiplicity, consistent with local charge conservation in a fragmentation-dominated scenario. In contrast, the epos-lhc model, especially when using the core corona implementation, exhibits a more intricate response, where the combined effects of hydrodynamic radial flow and longitudinal diffusion result in narrower azimuthal correlations and broader rapidity correlations. These features are characteristic signatures of collective dynamics, similar to those observed in heavy-ion collisions. Events with low spherocity, which are jetlike in nature, exhibit significantly narrower balance-function widths compared to isotropic events with high spherocity, illustrating that event-shape selection provides clear sensitivity to the underlying dynamics of particle production in pp collisions. The species dependence and event-shape sensitivity of the balance-function widths provide information about the hadronization dynamics and collectivity in small systems. These results demonstrate that multidimensional, particle-species-dependent balance-function measurements can disentangle the underlying mechanisms of charge correlations and mediumlike behavior in high-multiplicity pp collisions.

Subash Chandra Behera

Arvind Khuntia

System-size and event-shape dependence of particle-identified balance functions in proton-proton collisions at <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msqrt><mi>s</mi></msqrt><mo>=</mo><mn>13</mn></mrow></math> TeV using PYTHIA 8 and EPOS models

Several possible excesses around $ 95 $ GeV hint at an additional light scalar beyond the Standard Model. We examine the capability of the Circular Electron-Positron Collider (CEPC) to test this hypothesis in the Higgs-strahlung channel $ e^{+}e^{-} \to ZS $ with $ Z \to\mu^{+}\mu^{-} $ and $ S \to\tau^{+}\tau^{-} $ . A full detector simulation shows that the optimal center-of-mass energy for studying the 95 GeV light scalar is 210 GeV. A deep neural network classifier reduces the luminosity required for discovery by half. At $ L = 20\; \mathrm{ab}^{-1} $ , the $ 5\sigma $ sensitivity of the CEPC to the signal strength $ \mu_{\tau\tau}^{ZS} $ reaches 0.016 and 0.020 for $ \sqrt{s} = 210 $ GeV and 240 GeV, respectively. The corresponding thresholds for a 5% precision measurement are $ \mu_{\tau\tau}^{ZS} \gt 0.10 $ and $ \gt 0.12 $ . At $ \sqrt{s}=210 $ GeV (240 GeV), the $ 5\sigma $ coverage of all N2HDM-Flipped samples with $ \chi^2_{h_{95}} \lt 7.82 $ requires $ L=800\ \mathrm{fb}^{-1} $ (1.22 $ \mathrm{ab}^{-1} $ ). These results establish a 210 GeV run, augmented by machine-learning selection, as the most efficient strategy to confirm or refute the 95 GeV excess at future lepton colliders.

Yabo Dong

Manqi Ruan

Kun Wang

Haijun Yang

Jingya Zhu

Testing a 95 GeV Scalar at the CEPC with Machine Learning * This work was supported by the National Natural Science Foundation of China under Grant No. 12275066 and by the startup research funds of Henan University. The work of K. Wang was also supported by the Open Project of the Shanghai Key Laboratory of Particle Physics and Cosmology under Grant No. 22DZ2229013-3. The work of M. Ruan was also supported by the National Key Program for S&T Research and Development under Contract No. 2024YFA1610603. The work of H. Yang was also supported by the National Natural Science Foundation of China under Grant No. W2441004.