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

Due to Heisenberg’s uncertainty principle, atomic electrons localized around the nucleus exhibit a characteristic momentum distribution that, in elements with high atomic number, remains significant up to relativistic values. Consequently, in fixed-target experiments, atoms can effectively act as electron accelerators, increasing the centre-of-mass energy in collisions with beam particles. In this work, we leverage this effect to explore its potential for new physics searches. We consider positrons from beams of various energies annihilating with atomic electrons in a W fixed target. We compute the production rates of new vector bosons and pseudoscalar particles as functions of their couplings and masses. We show that the electron-at-rest approximation significantly underestimates the mass reach for producing these new states compared to the results obtained by properly accounting for atomic electron momenta. In particular, we estimate the sensitivity for detecting these new particles using the positron beam at the Beam Test Facility linac at the Laboratori Nazionali di Frascati, the H4 beamline in the CERN North Area, and the proposed Continuous Electron Beam Accelerator Facility of Jefferson Laboratory.

Italy

Fernando Arias-Aragón

Giovanni Grilli di Cortona

Estonia

Enrico Nardi

France

Léo Veissière

Atoms as electron accelerators for new physics searches

A new manifestly spacetime-supersymmetric prescription for superstring amplitude computations is given using the pure spinor formalism which does not contain subtleties from poles in the pure spinor ghosts. This super-Poincaré covariant prescription is related by a U(5)-covariant field redefinition to the Ramond-Neveu-Schwarz amplitude prescription where the pure spinor parameterizes the choice of SO(10)/U(5). For $\textit{F}$-term scattering amplitudes which preserve a subset of the spacetime supersymmetries, the new pure spinor amplitude prescription reduces to the previous pure spinor prescription.

Brazil

Nathan Berkovits

Equivalence proof of pure spinor and Ramond-Neveu-Schwarz superstring amplitudes

We calculate the hadronic scales $$r_0,$$ $$r_1$$ and their ratio $$r_0/r_1$$ on $${N_\textrm{f}}=2+1$$ flavor QCD ensembles generated by the CLS consortium. These scales are determined from a tree-level improved definition of the static force on the lattice, which we measure using Wilson loops. Our analysis involves various continuum and chiral extrapolations of data that cover pion masses between 134 MeV and 420 MeV and five lattice spacings down to 0.039 fm. We compare the potential scales to gradient flow scales by forming corresponding ratios. We find $$r_0=0.4757(64)$$ fm at the physical point. As a byproduct of our analysis we express the $${N_\textrm{f}}=3$$ QCD Lambda parameter determined by the ALPHA Collaboration in units of the scale $$r_0$$ and obtain $$r_0 \Lambda ^{(3)}_{\overline{\textrm{MS}}} = 0.820(28).$$ Furthermore we present results for the second derivative of the potential to study its shape and compare it to phenomenological potential models.

Germany

Tom Asmussen

Roman Höllwieser

Francesco Knechtli

Tomasz Korzec

The determination of potential scales in 2+1 flavor QCD

In light of the latest results from ACT observations we review a class of potentials labeled as fractional attractors, that can originate from Palatini gravity. We show that, for certain choices of the scalar potential <math altimg='si1.svg'><mi>V</mi><mo stretchy='false'>(</mo><mi>&#981;</mi><mo stretchy='false'>)</mo></math>, the fractional attractors predict both a spectral index <math altimg='si2.svg'><msub><mrow><mi>n</mi></mrow><mrow><mi>s</mi></mrow></msub></math> and a tensor-to-scalar ratio <italic>r</italic> that fall within the 1 <italic>&#963;</italic> region of the combined ACT+Planck data for a wide range of parameters. We also provide a numerical fit for the parameter space of these models in the case of a simple quadratic and quartic fractional potential.

Christian Dioguardi

United Arab Emirates

Antonio J. Iovino

Antonio Racioppi

Fractional attractors in light of the latest ACT observations

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

United Kingdom

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.

United States

Matthew Heydeman

Chiara Toldo

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

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