An analytical and numerical systematic study of the neutrino mass matrix with one texture zero is presented in a basis where the charged leptons are diagonal. Under the assumption that neutrinos are Dirac particles, the analysis is conducted in detail for the normal and inverted hierarchy mass spectra. Our study is performed without any approximations, first analytically and then numerically, using current neutrino oscillation data. The analysis constrains the parameter space in such a way that, among the six possible one-texture-zero patterns, only four are favored in the normal hierarchy and one in the inverted hierarchy by current oscillation data at the $3 \sigma$ level. Phenomenological implications for the lepton CP-violating phase and neutrino masses are also explored.

Colombia

Richard H. Benavides

Yessica Lenis

John D. Gómez

William A. Ponce

One texture zero for Dirac neutrinos in a diagonal charged lepton basis * Richard H. Benavides acknowledges additional financial support from Minciencias (CD82315 CT ICETEX 2021-1080)

Heavy Majorana neutrinos ($\textit{N}$) are predicted in many models of physics beyond the Standard Model. In this work, we explore the production and detection prospects of TeV-scale heavy neutrinos ( $ m_N \gtrsim 1 $ TeV) at a future 3 TeV Compact Linear Collider (CLIC). We focus on two distinct decay topologies: (i) $ N \to \ell^\pm W^\mp $ with hadronic $\textit{W}$ boson decay, leading to a final state with one charged lepton and a hadronic fat jet $ J_W $ ; and (ii) $ N \to \nu h $ with subsequent Higgs decay $ h \to b\bar{b} $ , yielding a Higgs-tagged fat jet $ J_h $ and $\not {E}_T$ . Based on comprehensive detector-level simulations and background analysis, we present both $ 2\sigma $ exclusion limits and $ 5\sigma $ discovery reaches in the $ m_N $ – $ |V_{\ell N}|^2 $ plane. We further extract 95% confidence level upper limits on the mixing parameter $ |V_{\ell N}|^2 $ and perform a detailed comparison with existing constraints from direct searches at future colliders and indirect global fits. Our findings demonstrate that a 3 TeV CLIC can improve the sensitivity to $ |V_{\ell N}|^2 $ by about two orders of magnitude compared with the projected reaches of future hadron colliders while remaining competitive with other CLIC search channels.

China

Yao-Bei Liu

Jing-Wei Lian

Searches for heavy neutrinos at a 3 TeV CLIC in fat jet final states * Yao-Bei Liu is supported by the Natural Science Foundation of Henan Province, China (252300421988), Jing-Wei Lian is supported by the National Natural Science Foundation of China (12447140) and the Natural Science Foundation of Henan Province, China (252300421771)

We study a three-loop induced neutrino mass scenario from a non-holomorphic modular $\textit{A}$ $_{4}$ flavor symmetry and obtain the minimum scenario leading to predictions of the lepton masses, mixing angles, and Dirac and Majorana phases, which are shown through chi square analyses. In addition, we discuss the lepton flavor violations, muon anomalous magnetic moment, lepton universality, and relic density of the dark matter candidate. Moreover, we show that our model can be extended to satisfy the observed relic density of dark matter within the limit of perturbation by adding one singlet scalar boson without changing predictions in the neutrino sector.

Takaaki Nomura

Hiroshi Okada

Neutrino mass model at a three-loop level from a non-holomorphic modular $\textit{A}$ $_{4}$ symmetry * Takaaki Nomura is supported by the Fundamental Research Funds for the Central Universities. Hiroshi Okada is supported by Zhongyuan Talent (Talent Recruitment Series) Foreign Experts Project

A fast-rolling axion can transfer its kinetic energy to gauge fields via the Chern-Simons coupling, leading to copious production of gauge quanta during inflation. The amplified gauge fields act as a source for both scalar and tensor perturbations. In this work, we propose a mechanism for suppressing scalar perturbations while sourcing strong tensor perturbations. We present an implementation of such a mechanism, demonstrating that sourced tensor perturbations are expected to be detected by upcoming next-generation cosmic microwave background experiments.

Kai-Ge Zhang

Jian-Feng He

Chengjie Fu

Zong-Kuan Guo

Suppression of scalar perturbations due to a heavy axion

The <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msup><mi>π</mi><mo>+</mo></msup><mi>p</mi></mrow></math> elastic scattering process is studied, using an effective Lagrangian approach that incorporates the <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>s</mi></math>-, <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>u</mi></math>-, and <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>t</mi></math>-channel amplitudes, including <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msup><mi mathvariant="normal">Δ</mi><mrow><mo>+</mo><mo>+</mo></mrow></msup><mrow><mo>(</mo><mn>1232</mn><mo>)</mo></mrow></mrow><mo>,</mo><mo> </mo><mrow><msup><mi mathvariant="normal">Δ</mi><mn>0</mn></msup><mrow><mo>(</mo><mn>1232</mn><mo>)</mo></mrow></mrow></math>, neutron, and <math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mi>ρ</mi><mn>0</mn></msup></math> contributions. By constructing the spin-density matrices from the scattering amplitudes, the von Neumann (entanglement) entropy is derived and associated with the spin degrees of freedom of the initial and final state particles. The entropy is computed by performing a partial trace over the spin subsystems, and its behavior is analyzed as a function of the center-of-mass energy <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>W</mi></math> and scattering angle <math xmlns="http://www.w3.org/1998/Math/MathML"><mi>θ</mi></math>. It is found that entropy exhibits nontrivial angular and energy dependences, reflecting the interplay among resonance contributions and background amplitudes. In particular, the <math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mi mathvariant="normal">Δ</mi><mrow><mo>+</mo><mo>+</mo></mrow></msup></math> region shows relatively low entanglement, suggesting spin coherence dominated by the specific resonant contribution, while the background contributions increase entropy due to mixed spin configurations. These results indicate that entanglement entropy can serve as a novel probe into the quantum structure of hadronic scattering amplitudes, providing complementary insights beyond conventional cross-section analyses.

South Korea

Seung-il Nam

Entanglement entropy for <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msup><mi>π</mi><mo>+</mo></msup><mi>p</mi></mrow></math> elastic scattering using a spin-density matrix

We analyze the sensitivity of the Large Hadron Collider (LHC) and the Future Circular Collider-hadron-hadron (FCC-hh) to the existence of pseudoscalar Higgs boson <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>A</mi><mn>0</mn></msub></math> predicted by the bestest little Higgs model. We study the tree-level (two and three body) and one-loop decays of the pseudoscalar, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>A</mi></mrow><mn>0</mn></msub><mo stretchy="false">→</mo><mi>b</mi><mover accent="true"><mrow><mi>b</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover><mo>,</mo><mi>t</mi><mover accent="true"><mrow><mi>t</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover><mo>,</mo><mi>γ</mi><mi>t</mi><mover accent="true"><mrow><mi>t</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover><mo>,</mo><mi>γ</mi><mi>b</mi><mover accent="true"><mrow><mi>b</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover><mo>,</mo><mi>Z</mi><mi>t</mi><mover accent="true"><mrow><mi>t</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover><mo>,</mo><mi>Z</mi><mi>b</mi><mover accent="true"><mrow><mi>b</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover><mo>,</mo><mi>W</mi><mi>t</mi><mover accent="true"><mrow><mi>b</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover><mo>,</mo><msub><mrow><mi>h</mi></mrow><mn>0</mn></msub><mi>t</mi><mover accent="true"><mrow><mi>t</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover><mo>,</mo><msub><mrow><mi>h</mi></mrow><mn>0</mn></msub><mi>b</mi><mover accent="true"><mrow><mi>b</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover></mrow></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>A</mi></mrow><mrow><mn>0</mn></mrow></msub><mo stretchy="false">→</mo><mi>γ</mi><mi>γ</mi><mo>,</mo><mi>γ</mi><mi>Z</mi><mo>,</mo><mi>Z</mi><mi>Z</mi><mo>,</mo><mi>g</mi><mi>g</mi><mo>,</mo><mi>W</mi><mi>W</mi></mrow></math>, respectively. In addition, we perform a phenomenological study of the production of the pseudoscalar <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>A</mi><mn>0</mn></msub></math> via gluon-fusion <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>g</mi><mi>g</mi><mo stretchy="false">→</mo><msub><mi>A</mi><mn>0</mn></msub><mo stretchy="false">→</mo><mi>Y</mi></math> processes, where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Y</mi><mo>≡</mo><mi>b</mi><mover accent="true"><mi>b</mi><mo stretchy="false">¯</mo></mover><mo>,</mo><mi>t</mi><mover accent="true"><mi>t</mi><mo stretchy="false">¯</mo></mover><mo>,</mo><mi>γ</mi><mi>γ</mi><mo>,</mo><mi>γ</mi><mi>Z</mi><mo>,</mo><mi>Z</mi><mi>Z</mi><mo>,</mo><mi>g</mi><mi>g</mi><mo>,</mo><mi>W</mi><mi>W</mi></math>. From the cross section of the processes of interest and the expected integrated luminosity of the LHC and FCC-hh, we determined the number of events that could be produced in both colliders.

Mexico

Y. Cervantes-Baltazar

E. Cruz-Albaro

A. Gutiérrez-Rodríguez

M.A. Hernández-Ruíz

D. Espinosa-Gómez

Search for the pseudoscalar Higgs boson <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>A</mi><mn>0</mn></msub></math> of the bestest little Higgs model at the LHC and FCC-hh

We investigate the shadow properties in a recently proposed rotating wormhole spacetime in the presence of a cold and non magnetized plasma environment surrounding the wormhole throat. Using the Hamilton Jacobi formalism, we derive the orbit equation under specific plasma density profiles, where we consider plasma as a dispersive medium and disregard its influence on the background geometry. The electron density distribution is chosen to preserve a generalized Carter constant. We explore the shadow cast by this class of rotating wormhole in the presence of both homogeneous and non-homogeneous plasma as seen by an asymptotic observer. The photon regions are visualized, and the influence of geometric parameters, plasma parameters, and the observer’s inclination angle with the rotation axis on the resulting shadow morphology is analyzed. We tried to implement constraints on the plasma and the geometrical parameters of the wormhole such as the spin parameter and the deviation (from Kerr) parameter in the backdrop of recent observational bounds coming from the deviation from circularity of the shadow boundary ( $$\Delta C$$ ) and deviation of the average shadow radius from Schwarzschild ( $$\delta $$ ). The bound on $$\Delta C$$ is satisfied by the theoretically allowed range of parameters thus not found very useful to put any constraint; we could impose stringent constraints on the parameters based on the observed value of $$\delta $$ . Comparing the optical characteristics of the image of these wormholes with those of Kerr black holes, we identify the features that could serve as discriminants for similar types of compact objects.

India

Pabitra Gayen

Ratna Koley

Decoding horizonless spacetime: plasma-induced features in a rotating wormhole shadow

We study frequentist confidence intervals based on graphical profile likelihoods (Wilks’ theorem, likelihood integration), and the Feldman–Cousins (FC) prescription, a generalisation of the Neyman belt construction, in a setting with non-Gaussian Markov chain Monte Carlo (MCMC) posteriors. Our simplified setting allows us to recycle the MCMC chain as an input in all methods, including mock simulations underlying the FC approach. We find all methods agree to within $$10 \%$$ in the close to Gaussian regime, but extending methods beyond their regime of validity leads to greater discrepancies. As a key consistency check, we recover a shift in cosmological parameters between low and high redshift cosmic chronometer data with the FC method, but only when one fits all parameters back to the mocks. We observe that fixing parameters, a common approach in the literature, risks underestimating confidence intervals.

Shubham Barua

Shantanu Desai

Ireland

Mauricio Lopez-Hernandez

Eoin Ó. Colgáin

On frequentist confidence intervals in a non-Gaussian regime

We investigate a scale-invariant general two-Higgs-doublet model with explicit <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math> violation. Using the Gildener-Weinberg method, we analyze the Higgs mass spectrum and couplings at the one-loop level, focusing on <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math> violation originating from both the Higgs potential and the Yukawa sector. We show that, due to the flatness condition, both <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math>-even and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math>-odd mixings between the 125 GeV Higgs boson and the heavier Higgs states arise only radiatively. As a result, the Higgs couplings to gauge bosons and fermions remain Standard Model-like, in agreement with current LHC constraints. We also find that the magnitude of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math> violation from the Higgs potential depends on the new complex Yukawa couplings and heavy Higgs masses, due to the flatness condition. In the case where only an additional top Yukawa coupling (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>ρ</mi><mrow><mi>t</mi><mi>t</mi></mrow></msub></math>) is present, the electron electric dipole moment is directly proportional to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Im</mi><msubsup><mi>ρ</mi><mrow><mi>t</mi><mi>t</mi></mrow><mn>2</mn></msubsup></math>. Furthermore, a nontrivial cancellation region can occur for a specific Higgs mass spectrum. We extend our analysis to scenarios with an additional complex electron Yukawa coupling, identifying the conditions under which the electron electric dipole moment is suppressed or vanishes.

Czechia

Dang Bao Nhi Nguyen

Vietnam

Eibun Senaha

Exploring <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math> violation and vanishing electric dipole moment of the electron in a scale-invariant general 2HDM

In this work, I discuss neutron stars with hyperons and antikaon condensate. To fix their coupling constants with the vector mesons of the quantum hadrodynamics, I use a unified scheme imposing that the Yukawa coupling is an invariant under SU(3) and SU(6) groups. Combining with the G-parity, I show that some expected results of the kaon and antikaon interaction with the nucleus are reobtained. In the same sense, the naive quark-isospin counting rule is restored in the SU(6) limit. Furthermore, the G-parity combined with the SU(3) gives us a clear picture of the role played by each meson in the kaon condensation. Numerical results show that the presence of antikaons severely compromises the stiffening of the equation of state by breaking the SU(6) symmetry.

Brazil

Luiz L. Lopes

Baryon and pseudoscalar meson octets within a unified broken SU(6) symmetry