Using accurate computational methods, we compute the quasinormal frequencies of a massive scalar field propagating near a black hole in the framework of non-minimal Einstein–Yang–Mills theory with a non-zero cosmological constant. We show that increasing the mass of the scalar field significantly decreases the damping rate of the quasinormal modes for both asymptotically flat and de Sitter black holes. However, in the de Sitter case, arbitrarily long-lived modes can exist, whereas in the asymptotically flat case, the damping rate never vanishes completely. In the limit of quasi-resonances, we observe a kind of universal behavior where the frequencies do not depend on the coupling constant. Applying the time-domain integration of perturbation equations we show that even when the effective potential has a negative gap, the scalar field is stable and the perturbations decay in time. In the regime of large mass of the field we obtain the analytic formula for quasinormal modes.

Spain

Alexey Dubinsky

Long-lived quasinormal modes and quasi-resonances around non-minimal Einstein–Yang–Mills black holes

Exotic neutral gauge bosons are powerful candidates for new physics beyond the Standard Model. The Left-Right Symmetric Model is a well-motivated framework that addresses several open questions in particle physics, including neutrino masses, dark matter, and the matter-antimatter asymmetry. It predicts new gauge bosons, such as $\textit{Z}$ and $\textit{W}$ , along with additional right-handed particles. We investigate the processes $\textit{μ}$ $\textit{μ}$ → $$ q\overline{q} $$ and $\textit{μ}$ $\textit{μ}$ → $\textit{l}$ $\textit{l}$ with the $\textit{Z}$ boson appearing as an intermediate state. The coupling strength, decay width and mass are the key parameters that govern the production and decay of the $\textit{Z}$ boson. The results indicate that the angular distributions of final-state particles are sensitive to the couplings of $\textit{Z}$ to the other fermions. The forward-backward asymmetry, derived from angular distributions, serves as a sensitive observable for distinguishing Standard Model predictions from those involving $\textit{Z}$ exchange. It also provides a powerful probe of the $\textit{Z}$ couplings to fermions. Compared with the current results at the Large Hadron Collider (LHC), the future muon collider has great potential to explore new parameter space with the $\textit{Z}$ boson.

China

Zongyang Lu

Jianing Qin

Honglei Li

Zhi-Long Han

Fei Huang

Chun-Yuan Li

Xing-Hua Yang

Zhong-Juan Yang

Phenomenological study of heavy neutral gauge bosons in the left-right symmetric model at future muon collider

A first search is presented for vector-like leptons (VLLs) exclusively decaying into a light long-lived pseudoscalar boson and a standard model $\textit{τ}$ lepton. The pseudoscalar boson is assumed to have a mass below the $\textit{τ}$ $\textit{τ}$ threshold, so that it decays exclusively into two photons. It is identified using the CMS muon system. The analysis is carried out using a data set of proton-proton collisions at a center-of-mass energy of 13 TeV collected by the CMS experiment in 2016–2018, corresponding to an integrated luminosity of 138 fb . Selected events contain at least one pseudoscalar boson decaying electromagnetically in the muon system and at least one hadronically decaying $\textit{τ}$ lepton. No significant excess of data events is observed compared to the background expectation. Upper limits are set at 95% confidence level on the vector-like lepton production cross section as a function of the VLL mass and the pseudoscalar boson mean proper decay length. The observed and expected exclusion ranges of the VLL mass extend up to 700 and 670 GeV, respectively, depending on the pseudoscalar boson lifetime.

Armenia

V. Chekhovsky

A. Hayrapetyan

V. Makarenko

A. Tumasyan

Austria

W. Adam

J. Andrejkovic

L. Benato

T. Bergauer

S. Chatterjee

K. Damanakis

M. Dragicevic

P. 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. Laer

P. Mechelen

N. Breugelmans

J. D’Hondt

S. Dansana

A. Moor

M. Delcourt

F. Heyen

Y. Hong

S. Lowette

I. Makarenko

D. Müller

S. Tavernier

M. Tytgat

G. Onsem

S. Putte

D. Vannerom

B. Bilin

B. Clerbaux

A. Das

I. Bruyn

G. Lentdecker

H. Evard

L. Favart

P. Gianneios

A. Khalilzadeh

F. Khan

K. Lee

A. Malara

M. Shahzad

L. Thomas

M. Vanden Bemden

C. Velde

P. Vanlaer

M. Coen

D. Dobur

G. Gokbulut

J. Knolle

L. Lambrecht

D. Marckx

K. Skovpen

N. Den Bossche

J. Linden

L. Wezenbeek

S. Bein

A. Benecke

A. Bethani

G. Bruno

C. Caputo

J. De Favereau De Jeneret

C. Delaere

I. Donertas

A. Giammanco

A. Guzel

Sa. Jain

V. Lemaitre

J. Lidrych

P. Mastrapasqua

T. Tran

S. Turkcapar

Brazil

G. Alves

E. Coelho

G. Correia Silva

C. Hensel

T. Menezes De Oliveira

C. Mora Herrera

P. Rebello Teles

M. Soeiro

E. Tonelli Manganote

A. Vilela Pereira

W. Aldá Júnior

M. Barroso Ferreira Filho

H. Brandao Malbouisson

W. Carvalho

J. Chinellato

Search for vector-like leptons with long-lived particle decays in the CMS muon system in proton-proton collisions at $$\sqrt{\text{s}}$$ = 13 TeV

Searches for pair-produced long-lived particles (LLPs) at the LHC commonly operate under the assumption that the two LLPs are identical. In this paper we entertain the possibility that the targeted final states are, instead, induced by a LLP pair with different masses and/or lifetimes. We propose a simple and intuitively-parametrised toy model in order to study such asymmetric production of LLPs. Using the recasting material of a recent search for displaced jets by the ATLAS collaboration, we demonstrate that we can set constraints on the production cross-section times branching fraction into jets for a variety of asymmetric LLP and mediator mass combinations.

France

Thomas Chehab

Louie Corpe

Andreas Goudelis

Abdelhamid Haddad

Louise Millot

Constraints on asymmetric production of long-lived scalars at the Large Hadron Collider

In this study, we investigate the gravitational collapses of rotating stellar systems accounting for gamma-ray burst jet progenitors. Based on the virial theorem of hadron collisional relaxations and Newtonian slow-rotating approximation, we analyze the conversion of gravitational binding energy into kinetic energy of hadrons, whose collisions produce photons and electron-positron pairs forming fireballs. Our qualitative analysis implies that rotation effects collimated and spinning fireballs with nontrivial angular momenta along the propagating direction, thus making ultra-relativistic jets. Results reveal the possible trends that the fireball becomes more collimated and the jet angle decreases as the total angular momentum and mass ratio $\textit{J}$/$\textit{M}$ of the slow-rotating collapsing core increases. Discussing the extrapolation of these trends to fast-rotating collapsing systems, we speculate that the ratio $\textit{J}$/$\textit{M}$ should be a key quantity for differentiating long bursts (massive core collapses) from short bursts (binary coalescence). We derive the intrinsic correlations of collimated fireball quantities that should be imprinted on a large sample of observed GRB data as empirical correlations.

Italy

She-Sheng Xue

Collimated and spinning fireballs for ultra-relativistic jets: long vs short gamma-ray bursts by angular momentum and mass ratio

We revisit the path integral formulation of bosonic string theory in locally-AdS spacetimes. Through a careful analysis of the worldsheet sigma model, we write down an effective theory of long strings living near the boundary of AdS . By directly computing the partition function of the long-string sector, we find that the worldsheet path integral naturally organizes itself into the Coulomb-gas expansion of a 2D conformal field theory on the asymptotic boundary, with the number of coulomb integrals being dual to the dimension of the moduli space of worldsheet instantons on the boundary of AdS . As such, we provide a derivation of the CFT dual of long strings in AdS for completely generic spacetime and worldsheet topologies.

United Kingdom

Bob Knighton

Deriving the long-string CFT in AdS

We propose a novel collider signature for neutral long-lived particles (LLPs): the emerging photon jet in the hadronic calorimeter (HCAL). This signature arises when a neutral LLP decays into photons within the HCAL, producing an electromagnetic shower without associated charged tracks or energy deposits in the electromagnetic calorimeter (ECAL). To demonstrate the viability of this approach, we consider the fermiophobic Higgs boson <math altimg='si1.svg'><msub><mrow><mi>h</mi></mrow><mrow><mi mathvariant='normal'>f</mi></mrow></msub></math> in the Type-I two-Higgs-doublet model as a representative scenario. In the ultralight regime ( <math altimg='si2.svg'><msub><mrow><mi>m</mi></mrow><mrow><msub><mrow><mi>h</mi></mrow><mrow><mi mathvariant='normal'>f</mi></mrow></msub></mrow></msub><mo linebreak='goodbreak' linebreakstyle='after'>&lt;</mo><mn>1</mn></math> GeV), <math altimg='si1.svg'><msub><mrow><mi>h</mi></mrow><mrow><mi mathvariant='normal'>f</mi></mrow></msub></math> decays exclusively into a photon pair via loop-induced processes, resulting in a suppressed width and consequently a long lifetime. Focusing on the golden channel <math altimg='si3.svg'><mi>p</mi><mi>p</mi><mo stretchy='false'>&#8594;</mo><msup><mrow><mi>H</mi></mrow><mrow><mo>&#177;</mo></mrow></msup><msub><mrow><mi>h</mi></mrow><mrow><mi mathvariant='normal'>f</mi></mrow></msub><mo stretchy='false'>&#8594;</mo><msup><mrow><mi>W</mi></mrow><mrow><mo>&#177;</mo></mrow></msup><msub><mrow><mi>h</mi></mrow><mrow><mi mathvariant='normal'>f</mi></mrow></msub><msub><mrow><mi>h</mi></mrow><mrow><mi mathvariant='normal'>f</mi></mrow></msub></math>, we analyze the exotic final state in which one <math altimg='si1.svg'><msub><mrow><mi>h</mi></mrow><mrow><mi mathvariant='normal'>f</mi></mrow></msub></math> decays in the ECAL and appears as a highly collimated photon jet (reconstructed as a single photon), while the other decays within the HCAL, producing an emerging photon jet. Through a detailed signal-to-background analysis incorporating realistic detector effects via fast simulation, we demonstrate that this signature achieves discovery-level sensitivity at the HL-LHC across a broad region of parameter space consistent with theoretical and experimental constraints. While our study focuses on the fermiophobic Higgs, the emerging photon jet in the HCAL constitutes a broadly applicable and previously unexplored strategy for detecting neutral LLPs decaying into photons, opening a new avenue in LLP searches at colliders.

South Korea

Jinheung Kim

Dongjoo Kim

Soojin Lee

Jeonghyeon Song

Emerging photon jets in the hadronic calorimeter: A novel signature of neutral long-lived particles at the LHC

The study of neutral $\textit{D}$-meson mixing provides a unique probe of long-distance effects in the charm sector, where Standard Model contributions are dominated by nonperturbative effects. In this work, we investigate the feasibility of using spectral reconstruction techniques within lattice QCD to compute the long-distance contributions to $\textit{D}$ − $$ {\overline{D}}^0 $$ mixing. After outlining the general formalism describing neutral meson mixing in the charm sector, we focus on the determination of the mixing amplitudes and the dimensionless parameters $\textit{x}$ = ∆$\textit{m}$ $\textit{/}$Γ and $\textit{y}$ = ∆Γ $\textit{/}$(2Γ ), which respectively encode the mass and width differences between the $\textit{D}$-meson mass eigenstates. We discuss in detail the required theoretical and computational framework, including the definition and renormalization of the four-quark operators entering the ∆$\textit{C}$ = 1 weak Hamiltonian, and strategies for evaluating the relevant correlation functions employing variance-reduction techniques. To extract the mixing ampli- tudes, we explore methods for reconstructing the spectral density from lattice correlators, providing preliminary assessments of the data quality required to reach the scaling regime, where the smearing width is small enough to yield physically meaningful results. Our findings lay the groundwork for future precision determinations of long-distance contributions to $\textit{D}$-meson mixing from first principles.

Switzerland

Matteo Carlo

Felix Erben

Maxwell Hansen

Long distance contributions to neutral $\textit{D}$-meson mixing from lattice QCD

We study two- and three-point correlation functions of chiral primary half-BPS operators in four-dimensional $$ \mathcal{N} $$ = 2 superconformal circular, cyclic symmetric quiver theories. Using supersymmetric localization, these functions can be expressed as matrix integrals which, in the planar limit, reduce to Fredholm determinants of certain semi-infinite matrices. This powerful representation allows us to investigate the correlation functions across the parameter space of the quiver theory, including both weak and strong coupling regimes and various limits of the number of nodes and the operator scaling dimensions. At strong coupling, the standard semiclassical AdS/CFT expansion diverges in the long quiver limit. However, by incorporating both perturbative corrections (in negative powers of the ’t Hooft coupling) and an infinite tower of nonperturbative, exponentially suppressed contributions, we derive a remarkably simple expression for the correlation functions in this limit. These functions exhibit exponential decay with increasing node separation and admit an interpretation within a five-dimensional effective theory. We determine the mass spectrum of excitations propagating along the emergent fifth dimension within this theory, finding it to be given by the zeros of Bessel functions.

Gregory Korchemsky

Alessandro Testa

Correlation functions in four-dimensional superconformal long circular quivers

Neutrino oscillations constitute an excellent tool to probe physics beyond the Standard Model. In this paper, we investigate the potential of the ESSnuSB experiment to constrain the effects of flavour-dependent long-range forces (LRFs) in neutrino oscillations, which may arise due to the extension of the Standard Model gauge group by introducing new U(1) symmetries. Focusing on three specific U(1) symmetries — $\textit{L}$ − $\textit{L}$ , $\textit{L}$ − $\textit{L}$ , and $\textit{L}$ − $\textit{L}$ , we demonstrate that ESSnuSB offers a favourable environment to search for LRF effects. Our analyses reveal that ESSnuSB can set 90% confidence level bounds of $\textit{V}$ < 2.99 × 10 eV, $\textit{V}$ < 2.05 × 10 eV, and $\textit{V}$ < 1.81 × 10 eV, which are competitive to the upcoming Deep Underground Neutrino Experiment (DUNE). It is also observed that reducing the systematic uncertainties from 5% to 2% improves the ESSnuSB limits on $\textit{V}$ . Interestingly, we find limited correlations between LRF parameters and the less constrained lepton mixing parameters $\textit{θ}$ and $\textit{δ}$ , preserving the robustness of ESSnuSB’s sensitivity to CP violation. Even under extreme LRF potentials ($\textit{V}$ ≫ 10 eV), the CP-violation sensitivity and $\textit{δ}$ precision remain largely unaffected. These results establish ESSnuSB as a competitive experimental setup for probing LRF effects, complementing constraints from other neutrino sources and offering critical insights into the physics of long-range forces.