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

In two-dimensional conformal field theories (CFT) in Minkowski spacetime, we study the spacetime distance between two events along two distinct modular trajectories. When the spatial line is bipartite by a single interval, we consider both the ground state and the state at finite different temperatures for the left and right moving excitations. For the free massless Dirac field in the ground state, the bipartition of the line given by the union of two disjoint intervals is also investigated. The modular flows corresponding to connected subsystems preserve relativistic causality. Locality along the modular flows of some fields is explored by evaluating their (anti-)commutators. In particular, the bilocal nature of the modular Hamiltonian of two disjoint intervals for the massless Dirac field provide multiple trajectories leading to Dirac delta contributions in the (anti-)commutators even when the initial points belong to different intervals, thus being spacelike separated.

United States

Dobrica Jovanovic

Mihail Mintchev

Erik Tonni

Modular evolutions and causality in two-dimensional conformal field theory

We explicitly compute correlation functions with the insertion of a continuous symmetry defect in bosonic field theories. To recover its expected action on the charged operators, the definition of the defect must be modified to include a specific contact term. This can be regarded as a singular background gauge field for the global symmetry. It can be traced to the definition of the generating functional for current correlators, where the source is akin to a background gauge field for the symmetry. For holographic theories, it has been proposed that continuous symmetry defects are realized in terms of non-BPS $\textit{D}$($\textit{q}$ – 1) branes. We argue that these can be regarded as $$ Dq/\overline{Dq} $$ system and show its application to the case of the baryonic symmetry in the Klebanov-Witten theory. The $$ Dq/\overline{Dq} $$ can be regarded as a particular regularization of the defect, holographically realizing the field theory discussion.

Spain

Hugo Calvo

Francesco Mignosa

Diego Rodriguez-Gomez

Continuous symmetry defects and brane/anti-brane systems

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

Using recent developments in expressing one-loop partition functions in Euclidean $\textit{AdS}$ space-times in terms of character integrals, we relate the one-loop effective action for a free field theory in $\textit{AdS}$ (comprised of a massless scalar field and a massless Majorana fermion field) to the partition function of the de Alfaro-Fubini-Furlan (DFF) conformal quantum mechanics (CQM) models on the two global $\textit{AdS}$ boundaries. The equal number of bosonic and fermionic degrees in the field theory guarantee that the one-loop calculation is free of all UV divergences except a logarithmic one consistent with the expected entanglement entropy behaviour in a CQM. Via a thermofield double representation, we compute the entanglement entropy between two copies of the $\textit{CFT}$ (CQM), each living near one of the two boundaries of global $\textit{AdS}$ , in a state at global time $\textit{τ}$ → – ∞. This entanglement entropy is expressed in terms of the logarithm of the regularised length of a closed particle trajectory infinitesimally near the rim of the Euclidean $\textit{AdS}$ disc. We view this relation between boundary quantum entanglement and a bulk geometrical quantity as the $\textit{AdS}$ /$\textit{CFT}$ version of the Ryu-Takayanagi conjecture in our setup. The boundary entanglement entropy is equal to 4 times the thermodynamic entropy read off from the regularised one-loop effective action in $\textit{AdS}$ . Further, we compute the bulk entanglement entropy associated with black hole horizons in Lorentzian $\textit{AdS}$ and show that it precisely matches the boundary entanglement entropy.

Portugal

Gabriel Cardoso

Bernardo Martins

Suresh Nampuri

Bulk-boundary entanglement correspondence and the Ryu-Takayanagi conjecture in an $\textit{AdS}$

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

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.

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.

Francisco Arco

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