We study the new $Z'$ boson as a portal for the production of Higgs bosons $h_0$ and $H_0$ predicted by the Bestest Little Higgs Model through Higgs-strahlung processes $\mu^+\mu^- \to (Z, Z') \to Zh_0, ZH_0$ . We focus on the resonant and nonresonant effects of the $Zh_0, ZH_0$ signals. In our analysis, we consider the center-of-mass energies of $\sqrt{s}=3, 4, 6, 10, 30$ TeV and integrated luminosities of ${\cal{L}}=2, 4, 6, 10, 30$ ${ {\rm{ab}}^{-1}}$ projected for a future muon collider. The possibility of performing precision measurements for Higgs bosons $h_0$ and $H_0$ is very promising for the future muon collider. Furthermore, our results may be useful to the High Energy Physics community. Complementarily, we generate and provide the Feynman rules necessary for studying processes $\mu^+\mu^- \to (Z, Z') \to Zh_0, ZH_0$ .

J.M. Martínez-Martínez

A. Gutiérrez-Rodríguez

E. Cruz-Albaro

M.A. Hernández-Ruíz

New $\textit{Z}$' boson of the bestest little Higgs model as a portal to signatures of Higgs bosons $\textit{h}$ $_{0}$ and $\textit{H}$ $_{0}$ at the future muon collider

Dark Matter can interact with electroweak gauge bosons via higher-dimensional operators, in spite of being neutral under gauge interactions, much like neutral atoms interact with photons through Rayleigh scattering. This study explores effective interactions between a real scalar Dark Matter particle, singlet under the SM gauge group, and electroweak gauge bosons. We present a comprehensive analysis of current constraints and projected sensitivities from both lepton and hadron colliders as well as direct and indirect detection experiments in testing Rayleigh Dark Matter interactions. We find that, thanks to the complementarity between collider experiments and cosmological probes, thermally produced Rayleigh Dark Matter at the hundreds of GeV scale can be thoroughly tested with the next generation of experiments. For lighter candidates, upcoming forecasts will explore uncharted parameter space, significantly surpassing the thermal Dark Matter benchmark.

Italy

Daniele Barducci

Dario Buttazzo

Alessandro Dondarini

Roberto Franceschini

Giulio Marino

Federico Mescia

Paolo Panci

Scalar Rayleigh Dark Matter: current bounds and future prospects

Both ATLAS and CMS have recently performed the first searches for a heavy new spin-0 resonance decaying into a lighter new spin-0 resonance and a $\textit{Z}$ boson, where the lighter spin-0 resonance subsequently decays into $$ t\overline{t} $$ pairs. These searches are of particular interest to probe Two Higgs doublet model (2HDM) parameter space regions that predict a strong first-order electroweak phase transition. In the absence of CP violation, the investigated decay is possible if the lighter and the heavier spin-0 particles have opposite CP parities. The analysis techniques employed by ATLAS and CMS do not distinguish between the two possible signatures $\textit{A}$ → $\textit{ZH}$ and $\textit{H}$ → $\textit{ZA}$, where $\textit{A}$ and $\textit{H}$ denote CP-odd and CP-even Higgs bosons, respectively, if both signals are predicted to have the same total cross sections. We demonstrate the capability of angular variables that are sensitive to spin correlations of the top quarks to differentiate between $\textit{A}$ → $\textit{ZH}$ and $\textit{H}$ → $\textit{ZA}$ decays, even in scenarios where both signals possess identical total cross sections. Focusing on masses of 600 GeV and 800 GeV as a representative 2HDM benchmark, we find that a distinction between the two possible channels is possible with high significance with the anticipated data from the high-luminosity LHC, if the invariant mass distribution of the $$ t\overline{t} $$ system is further binned in angular variables defined by the direction of flight of the leptons produced in the top-quark decays. Moreover, we find a moderate gain in experimental sensitivity due to the improved background rejection for both signals.

Germany

Francisco Arco

Spain

Thomas Biekötter

Panagiotis Stylianou

Georg Weiglein

Top-quark spin correlations as a tool to distinguish pseudoscalar $\textit{A}$ → $\textit{ZH}$ and scalar $\textit{H}$ → $\textit{ZA}$ signatures in $$ Zt\overline{t} $$ final states at the LHC

We study a class of supersymmetric Froggatt-Nielsen (FN) models with multiple U(1) symmetries and Standard Model (SM) singlets inspired by heterotic string compactifications on Calabi-Yau threefolds. The string-theoretic origin imposes a particular charge pattern on the SM fields and FN singlets, dividing the latter into perturbative and non-perturbative types. Employing systematic and heuristic search strategies, such as genetic algorithms, we identify charge assignments and singlet VEVs that replicate the observed mass and mixing hierarchies in the quark sector, and subsequently refine the Yukawa matrix coefficients to accurately match the observed values for the Higgs VEV, the quark and charged lepton masses and the CKM matrix. This bottom-up approach complements top-down string constructions and our results demonstrate that string FN models possess a sufficiently rich structure to account for flavour physics. On the other hand, the limited number of distinct viable charge patterns identified here indicates that flavour physics imposes tight constraints on string theory models, adding new constraints on particle spectra that are essential for achieving a realistic phenomenology.

United Kingdom

Andrei Constantin

Cristofero Fraser-Taliente

United States

Thomas Harvey

Lucas Leung

Andre Lukas

Quark masses and mixing in string-inspired models

Semiclassical quantization techniques are unreliable, if the magnitude of the quantum fluctuations becomes comparable with a classical background scale. This is the case, for example, for superstrings at temperatures close to the Hagedorn temperature. Here, we propose a non-standard treatment which aims to extend the semiclassical approach for type-II superstrings to such cases. This allows us to provide a well-posed reformulation of recent computations of the Hagedorn temperature in a large class of confining gauge theories. Along the way, we fill a gap in the literature by proving that the standard semiclassical partition function of the Green-Schwarz superstring can be made finite, by means of a suitable choice of integration measures, for any background worldsheet in a target spacetime satisfying the (type-IIA) supergravity field equations.

Tommaso Canneti

Federico Castellani

Wolfgang Mück

Vacuum configuration of winding superstrings from non-standard semiclassical quantization

We explain the ATOMKI anomaly with a very light $\textit{Z}$′ state that features non-anomalous and non-flavour-universal vector and axial-vector couplings to all leptons. This $\textit{Z}$′ comes from a theoretical framework with a spontaneously broken U(1)′ symmetry in addition to the Standard Model gauge group and is compliant with current measurements of the anomalous magnetic moments of the electron and the muon as well as beam dump experiments. The lepton flavour structure of this model allows for $\textit{Z}$′ couplings to all light neutrinos, suggesting the possibility of $\textit{Z}$′-mediated Non-Standard Interactions (NSIs) of neutrinos in matter, so that measurements of the strength parameters of the NSIs can constrain the value of the couplings. We use experimental constraints on NSIs of neutrinos using older TEXONO data and newer IceCube data. The IceCube data, in particular, strongly constrain the flavour universality of the leptonic vector current. The constraints enable us to define the region of parameter space of this theoretical scenario that can be pursued in further phenomenological analyses.

Sweden

Rikard Enberg

Türkiye

Yaşar Hiçyılmaz

Stefano Moretti

Carlos Heros

Harri Waltari

Constraints on the $\textit{X}$17 boson from IceCube searches for non-standard interactions of neutrinos

We derive the modular S and T matrices that generate the modular transformations on the characters of two dimensional Carrollian and warped CFT algebras. We verify that they satisfy some of their defining properties.

Austria

Ankit Aggarwal

Joan Simón

Modular matrices of 2d Carrollian and warped CFTs

Supersymmetric rotating 1/16-BPS black holes in $\textit{AdS}$ × $\textit{S}$ are expected to capture the average degeneracy of BPS states in the dual ABJM superconformal theory for given fixed charges. This has been successfully demonstrated for the superconformal index using complexified black hole metrics, but a naive Gibbons-Hawking calculation of the actual degeneracies in the low temperature limit is invalid due to large quantum fluctuations of the near horizon AdS metric. We argue that in a particular mixed grand/canonical ensemble, these fluctuations of the near-BPS Kerr-Newman black holes are described by a version of the $$ \mathcal{N} $$ = 2 super-Schwarzian theory with SU(1,1|1) symmetry. Using this description as well as properties of ABJM, we recover the large $\textit{N}$ superconformal index and find a characteristic “mass gap” of order $\textit{N}$ between the 1/16-BPS states and the lightest near BPS state. We further make a prediction for the operator dimension spectrum above the gap in the large $\textit{N}$, low $\textit{T}$ limit. Our results are consistent with the Bekenstein-Hawking formula at large energies, random matrix theory at low energies, and the microscopic index.

Matthew Heydeman

Chiara Toldo

The spectrum of near-BPS Kerr-Newman black holes and the ABJM mass gap

We develop a bootstrap strategy to obtain the six-point function of supergravitons in $\textit{AdS}$ × $\textit{S}$ from symmetry constraints and consistency conditions. Compared to previous bootstrap algorithms, a novel feature is the use of lightcone OPEs together with the chiral algebra constraint. This makes it possible to isolate different parts of the correlator and fix them separately. Our strategy allows us to gain a refined understanding of the power of different bootstrap constraints, which is also useful for computing more general correlators.

Portugal

Vasco Gonçalves

Maria Nocchi

China

Xinan Zhou

Dissecting supergraviton six-point function with lightcone limits and chiral algebra

In this work, we investigate the geodesic motion of both massless and massive test particles in the vicinity of a spherically symmetric Finslerian Hayward-like black hole (FHBH) that is coupled to a quintessence field (QF) and carries a global monopole (GM). By examining the combined effects of the GM and QF, we observe significant deviations in the geodesic structure for both null and time-like particles when compared to the conventional BH models. Additionally, we explore spin-0 scalar field perturbations by solving the massless Klein–Gordon equation in this modified BH space-time background and analyze the influence of the Finslerian geometry, GM, and QF on the resulting scalar perturbative potential. Using the effective potential derived from null geodesics, we compute the transmission and reflection coefficients and discuss their physical implications. Furthermore, we numerically calculate the quasinormal modes (QNMs) frequencies based on the scalar perturbations potential and assess how the Finslerian modifications, along with the presence of GM and QF, affect the QNM spectrum.

India

Faizuddin Ahmed

Jordan

Ahmad Al-Badawi

İzzet Sakallı

Some observable physical properties of Finslerian Hayward-like black hole with global monopole charge and quintessence field