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

On the basis of computer simulation, the ionization energy loss distributions (spectra) of high-energy positrons impinging on a silicon crystal at various angles $$\psi $$ with respect to the axis $$\langle 100\rangle $$ are considered. The method of simulation of high-energy particle ionization loss in oriented crystals is presented in detail. It is demonstrated that along with the probability of particle close collisions with atoms, the probability of distant collisions can be also sensitive to the particle position in the crystal lattice. Evolution of the ionization loss spectra with the change of crystal orientation relative to the incident particle momentum from the axial $$\langle 100\rangle $$ to the planar (100) and (110) with the increase of $$\psi $$ is investigated. It is shown that in the transition $$\langle 100\rangle \rightarrow (100)$$ the most probable energy loss $$E_\mathrm{{MP}}$$ experiences a sharp maximum and discontinuity, while in the transition $$\langle 100\rangle \rightarrow (110)$$ the amplitude of its variation is much smaller. Behavior of the average restricted energy loss $$E_\mathrm{{AV}}$$ in these transitions is investigated as well. Correlation of the dependences of $$E_\mathrm{{MP}}$$ and $$E_\mathrm{{AV}}$$ on $$\psi $$ with the change of the particle motion regime is discussed.

Ukraine

S. Trofymenko

I. Kyryllin

Evolution of high-energy positron ionization loss spectra in a silicon crystal with the change of its orientation from axial to planar

A precise determination of the CKM angle $\textit{γ}$ from $$ {B}_s^0 $$ oscillations in $$ {B}_s^0\to {D}_s^{\mp }{K}^{\pm } $$ decays offers a critical test of the Standard Model and probes for new physics. We present a comprehensive study on the prospects of measuring $\textit{γ}$ at a future Tera-$\textit{Z}$ factory, utilizing the baseline detector concept of the Circular Electron Positron Collider (CEPC). A two-dimensional simultaneous fit framework, incorporating flavor tagging, decay time resolution modeling, and acceptance corrections, is developed using full Monte Carlo simulations of $$ {B}_s^0\to {D}_s^{\mp}\left(\to {K}^{\mp }{K}^{\pm }{\pi}^{\mp}\right){K}^{\pm } $$ decays and inclusive background processes. The effective flavor tagging power reaches 23.6%, while the decay time resolution is determined to be 26 fs. Projecting to full statistics of signal events across three dominant $$ {D}_s^{-} $$ decay channels, we estimate a statistical precision of $\textit{σ}$($\textit{γ}$) = 0$\textit{.}$69 , which corresponds to 4.1 Tera-$\textit{Z}$ boson equivalent data. This study has established the feasibility of sub-degree level $\textit{γ}$ measurements at a $\textit{Z}$ factory, highlighting its unique advantages in time-dependent $\textit{CP}$ violation studies through ultra-precise vertexing and background suppression capabilities.

China

Ji Peng

Mingrui Zhao

Xiaolin Wang

Manqi Ruan

Hengne Li

Shanzhen Chen

Prospect for measurement of $\textit{CP}$-violating observables in $$ {B}_s^0\to {D}_s^{\mp }{K}^{\pm } $$ decays at a future $\textit{Z}$ factory

In this paper we propose a new paradigm for cosmology: a time dependent scalar condensate background originated from the quadratic $$(R + \alpha R^2)$$ Starobinsky model, where $\textit{R}$ is the Ricci scalar and $$\alpha $$ the coupling constant. In weak gravity limit the system decouples into a conventional graviton and a higher derivative scalar. It was shown earlier through works from our group (Chakraborty and Ghosh in Phys Dark Universe 35:100976, 2022; Ghosh in Phys. A: Stat. Mech. Appl. 407:245, 2014; Das et al. in Cosmology in R $$^{2}$$ -gravity: effects of a higher derivative scalar condensate background. ) that the latter can sustain an oscillatory lowest energy configuration or a $\textit{Geometric Condensate}$ as it consists entirely of metric degrees of freedom. In the present work, we study Gravitational Wave propagation in this condensate background. We show that the explicit time dependent nature of the condensate can generate spatial curvature and radiation-like contributions in the scale factor evolution in FLRW cosmology. Subsequently the condensate leaves its signature on the Gravitational Wave profile as it propagates in the condensate modified FLRW spacetime. The wave profile is calculated analytically in terms of Whittaker functions. The main novelty of the Geometric Condensate scheme is that no external (condensate) matter from outside has been considered.

India

Aurindam Mondal

Subir Ghosh

Gravitational wave propagation in a geometric condensate in Starobinsky cosmology

<p>We study the evolution of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Q</mi></math>-balls under a spontaneously broken global U(1) symmetry. <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Q</mi></math>-balls are stabilized by the conservation of U(1) charge, but when the symmetry is spontaneously broken, the resulting Nambu-Goldstone boson can carry charge away from the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Q</mi></math>-ball, potentially leading to charge leakage. To study this process in a controlled setting, we consider a scenario where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Q</mi></math>-balls first form under an unbroken U(1) symmetry, which is then spontaneously broken. We introduce two complex scalar fields: one responsible for forming the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Q</mi></math>-ball, and the other for spontaneously breaking the U(1) symmetry, allowing us to clearly separate the formation and symmetry-breaking phases. Using numerical simulations in a spherically symmetric system, we find that the evolution of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Q</mi></math>-balls depends sensitively on the structure of the interaction between the two fields and the magnitude of symmetry breaking. Depending on parameters, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Q</mi></math>-balls can completely decay, evaporate into smaller, stable <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Q</mi></math>-balls, or transition into oscillons/I-balls. In particular, we find that stable, localized remnants often survive the evolution over long timescales, especially when the symmetry-breaking scale is small. These results demonstrate that, even though spontaneous U(1) breaking can lead to significant energy and charge loss from <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Q</mi></math>-balls, stable localized objects with reduced or no charge can frequently survive and potentially contribute to cosmological relics.</p>

Japan

Masahiro Kawasaki

Kai Murai

Fuminobu Takahashi

<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Q</mi></math>-balls under a spontaneously broken U(1) symmetry

<p>We present a minimal cosmological solution to the hierarchy problem. Our model consists of a light pseudoscalar and an extra Higgs doublet in addition to the standard model field content. We consider a landscape of vacua with varying values of the electroweak vacuum expectation value (VEV). The vacuum energy in our model peaks in a region of the landscape where the electroweak VEV is nonzero and much smaller than the cutoff. During inflation, due to exponential expansion, such regions of the landscape with maximal vacuum energy dominate the universe in volume, thus explaining the observed smallness of the electroweak scale with respect to the cutoff. The pseudoscalar potential in our model is that of a completely generic pseudogoldstone boson—not requiring the clockwork mechanism—and its field value never exceeds its decay constant or the Planck scale. Our mechanism is robust to the variation of other model parameters in the landscape as the electroweak VEV is varied. It also predicts a precise and falsifiable relationship between the masses and couplings of the different Higgs boson mass eigenstates. Moreover, the pseudoscalar in our model can account for the observed dark matter relic density.</p>

Susobhan Chattopadhyay

Dibya S. Chattopadhyay

Rick S. Gupta

Cosmological Selection of a Small Weak Scale from Large Vacuum Energy: A Minimal Approach

We study a simplified model of two colourless heavy vector resonances in the singlet representation of SU(2) , with zero and unit hypercharge. We discuss mixing with the Standard Model gauge bosons due to electroweak symmetry breaking, semi-analytic formulae for production at proton colliders, requirements to obey the narrow width approximation and selected low energy constraints. We show current LHC constraints and sensitivity projections for the HL-LHC, HE-LHC, SPPC and FCC-hh on the charged and neutral heavy vectors. The utility of the simplified model Lagrangian is demonstrated by matching these results onto three explicit models: a weakly coupled abelian extension of the Standard Model gauge group, a weakly coupled non-abelian extension and a strongly coupled minimal composite Higgs model. All our results are presented in terms of physical resonance masses, using expressions which are accurate even at vector masses near the electroweak scale due to a parameter inversion we derive. We discuss the importance of this inversion and point out that its effect, and the effects of electroweak symmetry breaking, can remain important up to resonance masses of several TeV. Finally, we clarify the relation between this simplified model and the Heavy Vector Triplet (HVT) model, a simplified model for heavy SU(2) triplets with zero hypercharge, and provide exact and approximate matching relations.

United States

Michael Baker

Timothy Martonhelyi

Andrea Thamm

Italy

Riccardo Torre

A simplified model of Heavy Vector Singlets for the LHC and future colliders

The string and brane tensions do not have to be put in by hand, they can be dynamically generated, as in the case when we formulate string and brane theories in the modified measure formalism. Here we take the measure as a metric independent lagrange multiplier that forces some lagrangian density to be zero. Then string tension appears, but as an integration constant. It can be seen however that these string tensions are not universal, but rather each string and each brane generates its own tension. To make the string tension fully dynamical, a bulk field (the tension field) is introduced. As we have seen in previous publications, world sheet conformal invariance in the case of two different species of strings with different tension can produce braneworlds, Swampland constraints may be avoided. Here we introduce braneworld scenarios without singularities of the string tensions, although they still can grow to very large values, this is done by demanding a certain periodicity in one light like coordinate. Now we add another crucial observation; Dark matter to us may consist of matter made out of strings with different tensions because of decoupling of standard string interactions for strings with different tensions, although interactions mediated by the tension field can exist between strings of different tensions.

Bahamas

Israel

Germany

E. Guendelman

Strings with a different tension as dark matter

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

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 transfer the scenario of quantum network nonlocal correlation to the vicinity of a black hole’s event horizon, aiming to evaluate the impact of Hawking effect on network nonlocality within this specific context. In an entanglement swapping network with two bipartite resources and three parties, we examine two scenarios with distinct Hawking radiation locations: one where it affects the endpoint parties’ system and another where it impacts all parties’ system. In both cases, network nonlocality decays due to Hawking radiation and disappears entirely when the Hawking temperature reaches a critical threshold. However, we observe a striking phenomenon: when resource states are maximally entangled and the affected system belongs to the endpoint participants, network nonlocality diminishes but does not vanish throughout the radiation process. Subsequently, we extend our investigation to star and chain networks to evaluate how resource quantity and distribution influence network nonlocality under Hawking radiation. Our results indicate that star networks exhibit greater resilience against Hawking radiation in maintaining nonlocality.

Jia Ji

Kan He

Shu-Yuan Yang

Nonlocal correlation in quantum network near a Schwarzschild black hole