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.

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>

Using data samples collected by the BESIII detector located at the Beijing Electron Positron Collider, the cross sections of the process <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo></mrow></msup><mo stretchy="false">→</mo><msub><mrow><mi>f</mi></mrow><mrow><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>1285</mn><mo stretchy="false">)</mo><msup><mrow><mi>π</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>π</mi></mrow><mrow><mo>−</mo></mrow></msup></mrow></math> are measured at 45 center-of-mass energies from 3.808 to 4.951 GeV. An investigation on the energy-dependent cross section is performed, and no significant structure is observed.

China

M. Ablikim

Russia

M.N. Achasov

Sweden

P. Adlarson

Germany

O. Afedulidis

X.C. Ai

R. Aliberti

Italy

A. Amoroso

Q. An

Y. Bai

JINR

O. Bakina

I. Balossino

Y. Ban

H.R. Bao

Poland

V. Batozskaya

Mongolia

K. Begzsuren

N. Berger

M. Berlowski

M. Bertani

D. Bettoni

F. Bianchi

E. Bianco

A. Bortone

I. Boyko

United States

R.A. Briere

A. Brueggemann

H. Cai

X. Cai

A. Calcaterra

G.F. Cao

N. Cao

Türkiye

S.A. Cetin

J.F. Chang

G.R. Che

G. Chelkov

C. Chen

C.H. Chen

Chao Chen

G. Chen

H.S. Chen

H.Y. Chen

M.L. Chen

S.J. Chen

S.L. Chen

S.M. Chen

T. Chen

X.R. Chen

X.T. Chen

Y.B. Chen

Y.Q. Chen

Z.J. Chen

Z.Y. Chen

South Korea

S.K. Choi

G. Cibinetto

F. Cossio

J.J. Cui

H.L. Dai

J.P. Dai

A. Dbeyssi

R.E. de Boer

D. Dedovich

C.Q. Deng

Z.Y. Deng

A. Denig

I. Denysenko

M. Destefanis

F. De Mori

B. Ding

X.X. Ding

Y. Ding

J. Dong

L.Y. Dong

M.Y. Dong

X. Dong

M.C. Du

S.X. Du

Y.Y. Duan

Z.H. Duan

P. Egorov

Y.H. Fan

J. Fang

S.S. Fang

W.X. Fang

Y. Fang

Y.Q. Fang

R. Farinelli

L. Fava

F. Feldbauer

G. Felici

C.Q. Feng

J.H. Feng

Y.T. Feng

M. Fritsch

C.D. Fu

J.L. Fu

Y.W. Fu

H. Gao

X.B. Gao

Y.N. Gao

Cross section measurement of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo></mrow></msup><mo stretchy="false">→</mo><msub><mrow><mi>f</mi></mrow><mrow><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>1285</mn><mo stretchy="false">)</mo><msup><mrow><mi>π</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>π</mi></mrow><mrow><mo>−</mo></mrow></msup></mrow></math> at center-of-mass energies between 3.808 and 4.951 GeV

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.

Ya-Ping Xie

Brazil

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.

Jonathan J. Heckman

Max Hübner

Chitraang Murdia

On the holographic dual of a symmetry operator at finite temperature

We glue together two copies of pure anti–de Sitter (AdS) spacetime along their conformal boundaries creating a manifold without boundaries. The resulting space, which in dimension <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>d</mi><mo>+</mo><mn>2</mn></math> we denote by <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="normal">A</mi><mi mathvariant="normal">d</mi><msubsup><mrow><mi mathvariant="normal">S</mi></mrow><mrow><mo>±</mo></mrow><mrow><mi>d</mi><mo>+</mo><mn>2</mn></mrow></msubsup></mrow></math>, has the topology of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>S</mi><mn>2</mn></msup><mo>×</mo><msup><mi mathvariant="normal">Σ</mi><mi>d</mi></msup></math>, where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi mathvariant="normal">Σ</mi><mi>d</mi></msup></math> is a <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>d</mi></math> manifold without boundary. Acting with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="double-struck">Z</mi><mi>n</mi></msub></math> on the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>S</mi><mn>2</mn></msup></math> factor amounts to coupling a pair of membranes at the north and south poles of the two-sphere. Moreover, extending the domain of the two-sphere polar coordinate from <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">[</mo><mn>0</mn><mo>,</mo><mi>π</mi><mo stretchy="false">]</mo></math> to the interval <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">[</mo><mn>0</mn><mo>,</mo><mo stretchy="false">(</mo><mn>2</mn><mi>N</mi><mo>−</mo><mn>1</mn><mo stretchy="false">)</mo><mi>π</mi><mo stretchy="false">]</mo></math>, where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>N</mi><mo>&gt;</mo><mn>1</mn></math>, enables the coupling of one stack of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>N</mi></math> coincident membranes at each pole of the two-sphere (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>2</mn><mi>N</mi></math> membranes in total). Assuming the existence of a quantum gravity theory on the glued spacetime, we compute the classical approximation of the entanglement entropy across an entangling surface consisting of the two antipodal stacks of membranes. We find that the resulting entropy exhibits a boundary cutoff divergence that can be canceled by taking the limit of an infinite number of membranes. This large-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>N</mi></math> cancelation—possible only in the doubled, extended geometry without boundaries—yields a finite, universal quarter-area law. The calculation does not require details of the quantum theory other than its infrared limit, which we assume to be Einstein gravity.

Chile

Cesar Arias

Extended AdS spacetime without boundaries and entanglement without holography

The Atacama Cosmology Telescope (ACT) Collaboration has reported a scalar spectral index <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>n</mi><mi>s</mi></msub><mo>=</mo><mn>0.9743</mn><mo>±</mo><mn>0.0034</mn></math>. This is substantially larger than the classical prediction of nonminimally coupled inflation models such as Higgs Inflation, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>n</mi><mi>s</mi></msub><mo>≈</mo><mn>0.965</mn></math>. Here we revisit the unitarity-conserving nonminimally coupled inflation model proposed by R. N. Lerner and J. McDonald [<a href="http://dx.doi.org/10.1103/PhysRevD.82.103525">Phys. Rev. D 82, 103525 (2010)</a>]. We show that when the inflaton is a complex nonminimally coupled gauge singlet scalar with additional interactions in the Jordan frame to maintain unitarity, the model predicts <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>n</mi><mi>s</mi></msub><mo>=</mo><mn>0.9730</mn></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>r</mi><mo>≈</mo><mn>9</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>6</mn></mrow></msup></math> for scalar self-coupling <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>λ</mi><mo>=</mo><mn>0.1</mn></math>.

United Kingdom

John McDonald

Unitarity-conserving nonminimally coupled inflation and the ACT spectral index

We propose a simple, renormalizable scenario in which all of dark energy arises from a one-loop Coleman–Weinberg potential induced by a scalar field Yukawa-coupled exclusively to Standard-Model neutrinos. Classically, $$V_{\min }=0$$ , but neutrino loops lift the vacuum by $$\rho _{\text {DE}}=\frac{y^{2}m_{\nu }^{6}}{512\pi ^{4}m_{\phi }^{2}}$$ , matching the observed dark energy scale for $$y\approx 0.28m_{\phi }/$$ eV and $$m_{\nu }\sim 0.1\,$$ eV. We detail cosmological tracking, demonstrate stability against neutrino clumping, and show that rapid scalar oscillations leave no detectable imprint on current neutrino-oscillation experiments—though they provide a clear target for future high-precision probes. Compared to other mass varying neutrino models, our framework employs only a renormalizable quadratic potential, avoids unnatural hierarchies, and makes concrete, testable predictions.

Georgia

Z. Kepuladze

Quantum dark energy from neutrino loops: model, stability and oscillation imprints

To date, wormholes have not been observed. Dynamic wormholes are difficult to detect due to their transient existence or extremely low spacetime curvature contrast, while static wormholes rely on “exotic matter” that violates the Null Energy Condition and lack direct theoretical support. This study explores the mechanism of dynamic wormhole formation via gravitational collapse of Bose–Einstein Condensate (BEC) dark matter in generalized Vaidya spacetime. Under specific conditions, the gravitational collapse of BEC dark matter interacts with gravitational fields to trigger abrupt changes in spacetime topology. This process depends on special parameters that are more likely to be satisfied in extreme environments. During the collapse, the condensate properties of BEC influence the evolution of spacetime curvature, and its intrinsic oscillatory behavior may facilitate the formation of dynamic wormholes. The research deduces function constraints that satisfy various energy conditions, constructs a dynamic wormhole form adapted to generalized Vaidya spacetime, and derives the Hawking radiation expression and mass function constraints by combining Lorentz-breaking quantum gravity theory. This mechanism confirms the feasibility of dynamic wormhole formation, provides a new perspective for understanding the behavior of dark matter under extreme gravity and the evolution of spacetime topology, and advances wormhole research toward the analysis of dynamic formation processes.

Junjie Wei

Discussion on the feasibility of dynamic wormhole formation based on the gravitational collapse of Bose–Einstein condensed dark matter on generalized Vaidya space-time

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

In this paper, we investigate a digitised SU(2) lattice gauge theory in the Hamiltonian formalism. We use partitionings to digitise the gauge degrees of freedom and show how to define a penalty term based on finite element methods to project onto physical states of the system. Moreover, we show for a single plaquette system that in this framework the limit $$g\rightarrow 0$$ can be approached at constant cost.

Timo Jakobs

Marco Garofalo

Tobias Hartung

Cyprus

Karl Jansen

Johann Ostmeyer

Switzerland

Simone Romiti

Carsten Urbach

Dynamics in hamiltonian lattice gauge theory: approaching the continuum limit with partitionings of SU(2)