A search for flavor violating decays of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Z</mi></math> boson to charged leptons is performed using data from 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> collected 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>. Each of the decays <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Z</mi><mo stretchy="false">→</mo><mi>e</mi><mi>μ</mi></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Z</mi><mo stretchy="false">→</mo><mi>e</mi><mi>τ</mi></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Z</mi><mo stretchy="false">→</mo><mi>μ</mi><mi>τ</mi></math> is considered. The data are consistent with the backgrounds expected from standard model processes. For the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Z</mi><mo stretchy="false">→</mo><mi>e</mi><mi>μ</mi></math> channel the observed (expected) 95% confidence level upper limit on the branching fraction is <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>1.9</mn><mo stretchy="false">(</mo><mn>2.0</mn><mo stretchy="false">)</mo><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>7</mn></mrow></msup></math>, which is the most stringent direct limit to date on this process; the corresponding limits for the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Z</mi><mo stretchy="false">→</mo><mi>e</mi><mi>τ</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Z</mi><mo stretchy="false">→</mo><mi>μ</mi><mi>τ</mi></math> channels are <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>13.8</mn><mo stretchy="false">(</mo><mn>11.4</mn><mo stretchy="false">)</mo><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>6</mn></mrow></msup></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>12.0</mn><mo stretchy="false">(</mo><mn>5.3</mn><mo stretchy="false">)</mo><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>6</mn></mrow></msup></math>, respectively. Additionally, the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>e</mi><mi>μ</mi></math> final state is used to search for lepton flavor violating decays of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>Z</mi><mo>′</mo></msup></math> resonances in the mass range from 110 to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>500</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></mrow></math>. No significant excess is observed above the predicted background levels.

Armenia

A. Hayrapetyan

V. Makarenko

A. Tumasyan

Austria

W. Adam

J.W. Andrejkovic

L. Benato

T. Bergauer

M. Dragicevic

C. Giordano

P.S. Hussain

M. Jeitler

N. Krammer

A. Li

D. Liko

I. Mikulec

J. Schieck

R. Schöfbeck

D. Schwarz

M. Shooshtari

M. Sonawane

W. Waltenberger

C.E. Wulz

Belgium

T. Janssen

H. Kwon

D. Ocampo Henao

T. Van Laer

P. Van Mechelen

J. Bierkens

N. Breugelmans

J. D’Hondt

S. Dansana

A. De Moor

M. Delcourt

F. Heyen

Y. Hong

P. Kashko

S. Lowette

I. Makarenko

D. Müller

J. Song

S. Tavernier

M. Tytgat

G.P. Van Onsem

S. Van Putte

D. Vannerom

B. Bilin

B. Clerbaux

A.K. Das

I. De Bruyn

G. De Lentdecker

H. Evard

L. Favart

P. Gianneios

A. Khalilzadeh

F.A. Khan

A. Malara

M.A. Shahzad

L. Thomas

M. Vanden Bemden

C. Vander Velde

P. Vanlaer

F. Zhang

M. De Coen

D. Dobur

G. Gokbulut

J. Knolle

L. Lambrecht

D. Marckx

K. Skovpen

N. Van Den Bossche

J. van der Linden

J. Vandenbroeck

L. Wezenbeek

S. Bein

A. Benecke

A. Bethani

G. Bruno

A. Cappati

J. De Favereau De Jeneret

C. Delaere

A. Giammanco

A.O. Guzel

V. Lemaitre

J. Lidrych

P. Malek

P. Mastrapasqua

S. Turkcapar

Brazil

G.A. Alves

M. Barroso Ferreira Filho

E. Coelho

C. Hensel

T. Menezes De Oliveira

C. Mora Herrera

P. Rebello Teles

M. Soeiro

E.J. Tonelli Manganote

A. Vilela Pereira

W.L. Aldá Júnior

H. Brandao Malbouisson

W. Carvalho

Search for charged lepton flavor violating <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Z</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>Z</mi><mo>′</mo></msup></math> boson decays 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>

The exclusive <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>J</mi><mo>/</mo><mi>ψ</mi></mrow></math> photoproduction and the exclusive <math xmlns="http://www.w3.org/1998/Math/MathML"><mi mathvariant="normal">Υ</mi></math> photoproduction in proton-proton <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mo>(</mo><mi>p</mi><mi>p</mi><mo>)</mo></mrow></math> and proton-lead <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mo>(</mo><mi>p</mi><mi>Pb</mi><mo>)</mo></mrow></math> collisions at the energies available at the CERN Large Hadron Collider are investigated using the generalized parton distribution approach. Assuming the Goloskokov-Kroll model, we estimate the corresponding total cross sections and rapidity distributions considering different parametrizations for the unpolarized gluon distribution of the proton. In particular, we compare the linear predictions, associated with Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution, with those derived taking into account the leading nonlinear corrections resulting from gluon recombination. The dependence of our predictions on the choice for the factorization scale is discussed.

China

Ya-Ping Xie

Victor P. Gonçalves

Exclusive heavy-vector-meson photoproduction in <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>p</mi><mi>p</mi></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>p</mi><mi>Pb</mi></mrow></math> collisions within the generalized parton distribution approach: A phenomenological analysis

Topological symmetry operators of holographic large <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>N</mi></math> <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>CFT</mi></mrow><mrow><mi>D</mi></mrow></msub></mrow></math>’s are dual to dynamical branes in the gravity dual <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>AdS</mi></mrow><mrow><mi>D</mi><mo>+</mo><mn>1</mn></mrow></msub></mrow></math>. We use this correspondence to establish a dictionary between thermal expectation values of symmetry operators in the Euclidean <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>CFT</mi></mrow><mrow><mi>D</mi></mrow></msub></mrow></math> and the evaluation of gravitational saddles in the presence of a dynamical brane. Expectation values of 0-form symmetry operators in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>CFT</mi></mrow><mrow><mi>D</mi></mrow></msub></mrow></math> are then related to branes wrapped on volume minimizing cycles in the bulk, i.e., the Euclidean continuation of a black hole horizon. We illustrate with some representative examples, including gravity in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>AdS</mi></mrow><mrow><mn>3</mn></mrow></msub></mrow></math>, duality/triality defects in four-dimensional <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">N</mi><mo>=</mo><mn>4</mn></math> super Yang-Mills theory, and the dual of R-symmetry operators probing five-dimensional Bogomol’nyi–Prasad–Sommerfield black holes.

United States

Jonathan J. Heckman

Sweden

Max Hübner

Chitraang Murdia

On the holographic dual of a symmetry operator at finite temperature

We develop a unified dynamical systems framework for spatially flat FLRW cosmology in $\textit{f}$($\textit{Q}$) gravity, covering all three connection branches using a single set of Hubble-normalised variables without fixing the function $\textit{f}$($\textit{Q}$) a priori. This model-independent and connection-agnostic approach enables direct comparison across connection choices and uncovers structural features of the cosmological dynamics not visible in connection-specific formulations. While the existing works narrowly focus only on fixed point analysis, in our work we put special efforts to identify the invariant submanifolds, model-independent trajectories and physically viable regions of phase space across connections. For a broad class of viable $\textit{f}$($\textit{Q}$) models, we establish the generic existence of de Sitter attractors and matter-dominated fixed points in the two branches of connection, offering a robust route to late-time acceleration without fine-tuning. We further identify an invariant submanifold that yields $$\Lambda $$ CDM-like background evolution despite underlying dynamics distinct from General Relativity, providing a geometric origin for cosmic acceleration distinguishable only at the perturbation level. We also derive a first integral on this submanifold, allowing analytic reconstruction of the dynamical connection and uncovering hidden conservation laws. Another key feature we found is that while trivial connections exhibit strong parameter dependence, the nontrivial branches often feature parameter-independent behaviours. We also study the variation of the effective gravitational coupling, $$k_{\text {eff}}$$ , across branches and show how this can be constrained using astrophysical observations, which bridges theoretical viability with observational consistency in a novel way. Applying our framework to the illustrative model $$f(Q)=\alpha Q + \beta (-Q)^n$$ , we find late-time acceleration and $$\Lambda $$ CDM-like behaviour without vacuum energy. Finally, we propose a general route for extending dynamical systems analysis to broader classes of $\textit{f}$($\textit{Q}$) models using the $$m_i$$ -hierarchy method. This framework enables closure for models previously inaccessible to standard approaches and offers a diagnostic tool for identifying structurally viable cosmologies within modified gravity theories.

India

Jibitesh Dutta

Wompherdeiki Khyllep

Thailand

South Africa

Saikat Chakraborty

Daniele Gregoris

Khamphee Karwan

A unified dynamical systems framework for cosmology in $\textit{f}$($\textit{Q}$) gravity: generic features across the connection branches

We propose a unified model of dark energy and inflation through the Markov–Mukhanov modification of the Einstein–Hilbert action, where the matter sector is coupled to gravity via a scalar coupling function depending only on the energy density of the matter content. We assume that the coupling function encodes the UV corrections to the standard model of cosmology and we determine the form of the coupling that allows for the dark energy component to be dynamical and act as the inflaton field in the early universe. Interestingly we show that our model, in order to account for inflation, prefers a dark energy equation of state with $\textit{w}$ close but not equal to $$-1$$ in agreement with the latest DESI data.

Kazakhstan

Hrishikesh Chakrabarty

Daniele Malafarina

A unified model of dark energy and inflation from the Markov–Mukhanov action

We investigate the reconstruction of standard and generalized Rastall gravity inflationary models, using the scalar spectral index and the Rastall parameter expressed as functions of the number of <math altimg='si3.svg'><mrow><mi>e</mi><mo linebreak='goodbreak'>&#8722;</mo></mrow></math>folds <italic>N</italic>. Within a general formalism, we derive the effective potential in terms of the relevant cosmological parameters and the Rastall parameter for these gravity frameworks. As a specific example, we analyze the attractor <math altimg='si4.svg'><mrow><msub><mi>n</mi><mi>s</mi></msub><mrow><mo>(</mo><mi>N</mi><mo>)</mo></mrow><mo linebreak='goodbreak'>&#8722;</mo><mn>1</mn><mo>&#8733;</mo><msup><mi>N</mi><mrow><mo>&#8722;</mo><mn>1</mn></mrow></msup></mrow></math>, first by considering constant values of the Rastall parameter to reconstruct the inflationary stage in standard Rastall gravity, and then by assuming a linear dependence on the number of <math altimg='si3.svg'><mrow><mi>e</mi><mo linebreak='goodbreak'>&#8722;</mo></mrow></math>folds <italic>N</italic> to reconstruct the inflationary model in generalized Rastall gravity. Thus, the reconstruction of the potential <italic>V</italic>( <italic>&#981;</italic>) is obtained for both standard and generalized Rastall gravity inflationary models. In both frameworks, we constrain key parameters of the reconstructed models during inflation using the latest observational data from Planck.

Chile

Ramón Herrera

Carlos Ríos

Reconstructing inflation in a generalized Rastall theory of gravity

Given that dark matter and normal matter are nontrivially unified in a grand unified theory, called dark grand unification, we derive novel residual theories at low energy explaining dark matter and neutrino mass. The first chain of which is $\textit{E}$ → SU(3) ⊗ SU(3) ⊗ SU(3) , which contains a matter parity by itself stabilizing a dark matter candidate and producing neutrino mass via a seesaw. The second chain is Trinification → SU(3) ⊗ SU(3) ⊗ U(1) ⊗ U(1) , which results in a novel family-universal 3-3-1-1 model, opposite to the normal 3-3-1-1 (or corresponding 3-3-1) model. Surprisingly, it is a variant of both minimal 3-3-1 model and 3-3-1 model with right-handed neutrinos since both $\textit{e}$ and $\textit{ν}$ are located at the bottoms of lepton triplets. Since this universal 3-3-1-1 model is properly embedded in the trinification, the above matter parity works governing dark matter stability as well as suppressing unwanted fermion mixings. Further, neutrino masses are naturally generated by a canonical seesaw combined with a scotogenic scheme.

Vietnam

Phung Dong

Do Huong

Implications of a dark grand unification

We investigate the sensitivity of a companion neutrino detector situated in the plane of a high-energy, high-intensity muon storage ring to elastic $\textit{ν}$ and $\textit{ν}$ scattering on electrons (E$\textit{ν}$ES). Assuming a muon collider with center-of-mass energies of up to 10 TeV, we report sensitivity to the weak couplings $\textit{g}$ and $\textit{g}$ up to around 0.05% relative error, and sensitivity to the weak mixing angle in the momentum transfer $\textit{Q}$ ∈ [10 , 2] GeV range up to around 0.03% relative error. E$\textit{ν}$ES measurements with high-energy muon storage rings allow one to directly interrogate the momentum-transfer regime associated with the NuTeV anomaly. This level of precision allows unique sensitivity to the momentum-dependence of sin θ . We estimate that with the neutrinos from a $\textit{E}$ = 1.5 TeV (or higher) muon collider, the hypothesis that sin $\textit{θ}$ does not “run” can be safely ruled out.

André Gouvêa

Adrian Thompson

Electroweak observables in neutrino-electron scattering from a muon storage ring

We present a fully backreacted Einstein-Maxwell-Dilaton–flavor model with dynamical light and strange sectors, calibrated to lattice QCD using a machine-learning–assisted spectral method. The model reproduces the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>2</mn><mo>+</mo><mn>1</mn></mrow></math>-flavor equation of state and chiral dynamics with quantitative accuracy, and maps the Columbia plot with a tricritical point at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msubsup><mrow><mi>m</mi></mrow><mrow><mi>s</mi></mrow><mrow><mi>tri</mi></mrow></msubsup><mo>≃</mo><mn>21</mn><mtext> </mtext><mtext> </mtext><mi>MeV</mi></mrow></math> and a critical mass <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mi>c</mi></msub><mo>≃</mo><mn>0.785</mn><mtext> </mtext><mtext> </mtext><mi>MeV</mi></math>, consistent with lattice results. At finite density, it yields a crossover-to-first-order transition and predicts a critical endpoint at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>T</mi><mi>C</mi></msub><mo>=</mo><mn>75.4</mn><mtext> </mtext><mtext> </mtext><mi>MeV</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>μ</mi><mi>C</mi></msub><mo>=</mo><mn>768</mn><mtext> </mtext><mtext> </mtext><mi>MeV</mi></math>, within the reach of heavy-ion experiments. These findings establish a unified holographic framework for the QCD phase structure across quark masses and baryon density, providing the first consistent and quantitative description of both deconfinement and chiral transitions within a single holographic model.

Jin-Yang Shen

Xin-Yi Liu

Jin-Rui Wu

Yue-Liang Wu

Zhen Fang

Toward a holographic realization of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>2</mn><mo>+</mo><mn>1</mn></mrow></math>-flavor QCD phase structure

Dark photons with kinetic mixing are compelling mediators for the interactions between dark matter and Standard Model particles. While most experimental searches focus on fully visible or fully invisible decays of dark photons, we explore processes that involve dark Higgs-strahlung, i.e. the emission of a dark Higgs boson connected to the mass generation of the dark photon. If the dark Higgs boson is the lightest dark sector particle, it is expected to be long-lived and decay into Standard Model particles via Higgs mixing. At electron-positron colliders, dark Higgs-strahlung may occur either in isolation (leading to a single displaced vertex and missing energy) or accompanied by a photon from initial-state radiation. Both signatures offer distinctive kinematic features, such as peaks in photon energy or missing invariant mass, which enable efficient background suppression and enhance sensitivity beyond existing searches. Our study suggests that Belle II could significantly improve coverage of dark sector models by targeting this previously unexplored final state and that combining dark Higgs-strahlung events with and without additional photon offers great potential for reconstructing the properties of the dark sector.

Germany

Francesca Acanfora

Felix Kahlhoefer

Dark Higgs-strahlung at Belle II: a distinctive dark sector signature with displaced vertices and missing energy