We study the interaction between photons, dark photons, and axions at future lepton colliders, focusing on single-photon events with missing energy as the experimental signature. We find that future facilities such as the International Linear Collider, Circular Electron-Positron Collider, and Future Circular Collider will be sensitive to the axion–photon–dark photon coupling down to the order of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mn>10</mn><mrow><mo>−</mo><mn>4</mn></mrow></msup><mtext> </mtext><mtext> </mtext><msup><mrow><mi>GeV</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></math> for dark photon masses around <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">O</mi><mo stretchy="false">(</mo><mn>10</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi><mo stretchy="false">)</mo></math>, assuming that the axion is extremely light and escapes detection. We further show that longitudinal beam polarization at the International Linear Collider can enhance the signal significance by a factor of 4, providing the strongest projected reach in the model parameter space. Existing constraints from Large Electron-Positron II are analyzed for comparison. Furthermore, the mass of dark photon can be determined by measuring the sharp dropoff in the distribution of the recoil mass.

Taiwan

Chuan-Ren Chen

Yuan-Feng Hsieh

Vietnam

Van Que Tran

Probing the axion-photon-dark photon interaction at future <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math> colliders

We investigate the general susceptibilities in the charm sector by using the van der Waals hadron resonance gas model (VDWHRG).We argue that the ideal hadron resonance gas, which assumes no interactions between hadrons, and the excluded volume hadron resonance gas, which includes only repulsive interactions, fail to explain the lattice quantum chromodynamics (lQCD) data at very high temperatures. In contrast, the VDWHRG model, incorporating both attractive and repulsive interactions, extends the degree of agreement with lQCD up to nearly 180 MeV. We estimate the partial pressure in the charm sector and study charm susceptibility ratios in a baryon-rich environment, which is tricky for lQCD due to the fermion sign problem. Our study further solidifies the notion that the hadrons should not be treated as noninteracting particles, especially when studying higher order fluctuations, but rather one should consider both attractive and repulsive interactions between the hadrons.

India

Kangkan Goswami

Kshitish Kumar Pradhan

Mexico

Dushmanta Sahu

Raghunath Sahoo

Partial pressure and susceptibilities of the charmed sector in the van der Waals hadron resonance gas model

We study flavor-changing bottom quark radiative decay $ b {\rightarrow} s \gamma $ induced at the one-loop level within the minimal gauged two-Higgs-doublet model (G2HDM). Among the three new contributions to this rare process in G2HDM, we find that only the charged Higgs $ {\cal{H}}^\pm $ contribution can be constrained by the current global fit data in $\textit{B}$-physics. The other two contributions from complex vectorial dark matter $ {\cal{W}} $ and dark Higgs $ {\cal{D}} $ are not sensitive to the current data. Incorporating theoretical constraints imposed on the scalar potential and electroweak precision data for the oblique parameters, we exclude mass regions $ m_{\cal{H}}^\pm \lesssim 250 $ GeV and $ m_{\cal{D}} \lesssim 100 $ GeV at the 95% confidence level.

China

Che-Hao Liu

Qiaoyi Wen

Fanrong Xu

Tzu-Chiang Yuan

New contributions to $\textit{b}$ → $\textit{sγ}$ in the minimal G2HDM * Supported in part by the National Natural Science Foundation of China (19Z103010239, 12350410369 (VQT), U1932104 (FRX)) and the NSTC (111-2112-M-001-035 (TCY))

General one-loop formulas for loop-induced processes $gg/\gamma \gamma \rightarrow \phi_i\phi_j$ with $\phi_i\phi_j = hh,~hH,~HH$ are presented in this paper. The analytic expressions evaluated in this study are valid for a class of Higgs Extensions of the Standard Model, $\textit{e.g.,}$ Inert Doublet Higgs, Two Higgs Doublet, Zee-Babu, and Triplet Higgs Models$\textit{.}$ Analytic expressions for one-loop form factors are expressesd in terms of the basic scalar one-loop two-, three-, and four-point functions following the output format of the packages $ {\tt LoopTools}$ and $ {\tt Collier}$ . Hence, physical results can be evaluated numerically using one of these packages. The analytic results are tested using several checks such as the ultraviolet finiteness and infrared finiteness of the one-loop amplitudes. Furthermore, the amplitudes obey the ward identity due to massless gauge bosons in the initial states. This identity is also verified numerically. Regarding applications, we present the phenomenological results for the investigated processes in the Zee-Babu model as a typical example. In particular, production cross-sections for the processes $\gamma \gamma\rightarrow hh$ are scanned over the parameter space of the Zee-Babu Model.

Khiem Hong Phan

Dzung Tri Tran

Thanh Huy Nguyen

One-loop analytical expressions for $\textit{gg}$/$\textit{γγ}$ → ϕ$_{i}$ϕ$_{j}$ in Higgs extensions of the standard model and their applications * This research is supported by Vietnam National Foundation for Science and Technology Development (103.01-2023.16). Khiem Hong Phan and Dzung Tri Tran express their gratitude to all the valuable support from Duy Tan University, for the 30th anniversary of establishment (Nov. 11, 1994 - Nov. 11, 2024) towards ''Integral, Sustainable and Stable Development''

Recent reports from the Large Hadron Collider indicate two excesses: one in the lighter Higgs mass region around 95 GeV, and another in the rare <italic>Z&#947;</italic> final state of the Standard Model (SM) 125 GeV Higgs decay. These anomalies are analyzed within the minimal gauged two-Higgs-doublet model (G2HDM). A viable parameter space in G2HDM is identified that can account for both excesses. Within the viable parameter space, we find a strong correlation between the signal strengths of the SM 125 GeV Higgs decays into <italic>&#947;&#947;</italic> and <italic>Z&#947;</italic> modes. However, this correlation does not extend to the lighter 95 GeV Higgs.

Morocco

Abdesslam Arhrib

When the Standard Model Higgs meets its lighter 95 GeV twin

We formulate fermionic versions, for any number of spatial dimensions, of the van der Waals and Casimir-Polder interactions and study their properties. In both cases, the systems we introduce contain localized “atoms”: two-level systems, coupled to a vacuum Dirac field. This Dirac field plays here a role akin to the electromagnetic field in the van der Waals case. In this context, bag model conditions for the Dirac field serve as the analog of the “mirror” in the Casimir-Polder effect. We found that, in this case, the resulting interaction is repulsive.

Argentina

C.D. Fosco

G. Hansen

Fermionic van der Waals and Casimir-Polder interactions

The precision measurements of the muon magnetic moment and the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>W</mi></mrow></math> boson mass have sparked interest in the potential deviations from standard model (SM) predictions. While it may be premature to attribute any excesses in these precision measurements to new physics, they do offer a valuable indication of potential directions for physics beyond the SM. Additionally, the particle nature of dark matter (DM) remains a crucial enigma. Despite the absence of any definitive DM signal in direct detection and collider experiments, the Galactic Center GeV <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>γ</mi></math>-ray excess and the AMS-02 antiproton (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mover accent="true"><mi>p</mi><mo stretchy="false">¯</mo></mover></math>) excess could potentially offer hints related to the evidence of DM. Motivated by these observations, we propose a simple DM model that addresses all these issues. This model extends the SM by incorporating singlet and doublet Dirac fermion fields, along with a doublet complex scalar field. For the viable parameter regions in this model, we find that future upgrades of the Large Hadron Collider and DM direct detection experiments can only partially probe them, while future high-energy muon colliders hold promise for exploring the unexplored parameter space.

Yi-Zhong Fan

Yao-Yu Li

Chih-Ting Lu

Xiao-Yi Luo

Tian-Peng Tang

Yue-Lin Sming Tsai

Current status of inert Higgs dark matter with dark fermions

We explore a novel scenario involving Abelian–non-Abelian kinetic mixing within the framework of the Standard Model effective field theory (SMEFT) and its extension with a real triplet scalar field. In SMEFT, this mixing arises exclusively from a dimension-6 operator involving the Standard Model Higgs doublet, while the real triplet scalar field introduces an additional dimension-5 operator. We derive the modifications to electroweak gauge boson properties and impose constraints using electroweak precision data. In SMEFT, we find that <math><mi>Z</mi></math>-pole data at the Large Electron–Positron Collider imposes a stringent constraint on the kinetic mixing parameter, requiring it to be less than <math><mi>O</mi><mo>(</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>4</mn></mrow></msup></math>), which corresponds to a new physics scale of about 10 TeV. In the <math><mrow><mi>SMEFT</mi><mo>+</mo><mi>triplet</mi></mrow></math> scenario, the constraint can be significantly relaxed with a sizeable triplet vacuum expectation value while preserving custodial symmetry in a finely tuned parameter space. Future measurements from the Circular Electron Positron Collider could probe the kinetic mixing parameter down to an order of magnitude smaller. Constraints from the Higgs signal strength data, <math><msub><mi>B</mi><mi>s</mi></msub><mo>→</mo><msup><mi>μ</mi><mo>+</mo></msup><msup><mi>μ</mi><mo>−</mo></msup></math>, and muon (<math><mrow><mi>g</mi><mo>−</mo><mn>2</mn></mrow></math>) are also discussed.

Exploring Abelian–non-Abelian kinetic mixing in SMEFT and beyond

This paper is designed for heavy pulsars coming from the Neutron Star Interior Composition Explorer. The research model is describe by Einstein field equations for anisotropic fluid configuration with spherical symmetry. As per present perceptiveness, modified non-linear Van der Waals equation of state is used to relate physical variables. The continuity of inner and outer matter is obtained by comparing inner spacetime to outer Schwarzschild metric. The physical viability of this model is evaluated and further it is compared with observational data of pulsars PSR J0348+0432, PSR J0740+6620 and PSR J0030+0451. The model fulfils all physical and mathematical characteristics of the dense structure studies. It offers the factual proofs carried by evolution of celestial configurations. The working model presented here is physically viable and shows stable behaviour.

Pakistan

S. Mardan

A. Khalid

Rubab Manzoor

Lebanon

Czechia

Muhammad Riaz

Anisotropic model observing pulsars from Neutron Star Interior Composition with modified Van der Waals equation of state

Studying the thermodynamics of the systems produced in ultra-relativistic heavy-ion collisions is crucial in understanding the QCD phase diagram. Recently, a new avenue has opened regarding the implications of large initial angular momentum and subsequent vorticity in the medium evolution in high-energy collisions. This adds a new type of chemical potential into the partonic and hadronic systems, called the rotational chemical potential. We study the thermodynamics of an interacting hadronic matter under rotation, formed in an ultra-relativistic collision. We introduce attractive and repulsive interactions through the van der Waals equation of state. Thermodynamic properties like the pressure (P), energy density ( $$\varepsilon $$ <math> <mi>ε</mi> </math> ), entropy density (s), trace anomaly ( $$(\varepsilon - 3P)/T^{4}$$ <math> <mrow> <mrow> <mo>(</mo> <mi>ε</mi> <mo>-</mo> <mn>3</mn> <mi>P</mi> <mo>)</mo> </mrow> <mo>/</mo> <msup> <mi>T</mi> <mn>4</mn> </msup> </mrow> </math> ), specific heat ( $$c_\textrm{v}$$ <math> <msub> <mi>c</mi> <mtext>v</mtext> </msub> </math> ) and squared speed of sound ( $$c_\textrm{s}^{2}$$ <math> <msubsup> <mi>c</mi> <mtext>s</mtext> <mn>2</mn> </msubsup> </math> ) are studied as functions of temperature (T) for zero and finite rotation chemical potential. The conserved charge fluctuations, which can be quantified by their respective susceptibilities, are also studied. The rotational (spin) density corresponding to the rotational chemical potential is explored. In addition, we explore the possible liquid–gas phase transition in the hadron gas with van der Waals interaction in the T – $$\omega $$ <math> <mi>ω</mi> </math> phase space.

Kshitish Pradhan

Bhagyarathi Sahoo

Thermodynamics of a rotating hadron resonance gas with van der Waals interaction