arXiv subjects

Zhanhong Lei

Publications and source records attributed to Zhanhong Lei.

7 recordsLinked to original sources

arXiv2026

Line-of-sight magnetic-field propagation effects on axion-like particle constraints from GRB 221009A

High-energy photons from GRB 221009A provide a powerful opportunity to probe axion-like particles (ALPs) through photon-ALP oscillations in cosmic magnetic fields. We revisit the ALP constraints implied by the LHAASO observation of this burst, with particular emphasis on the magnetic-field environments encountered along the line of sight. We include the host-galaxy, intergalactic, and Milky-Way magnetic fields and assess their respective impacts on the photon survival probability and on the exclusion limits in the ALP mass-coupling plane. We show that the constraints are only mildly affected by the choice of host-galaxy and Galactic magnetic-field models, but can change significantly once the intergalactic magnetic field is varied. Its field strength, coherence scale, and stochastic properties can all leave visible imprints on the derived exclusion contours, and in some cases generate pronounced oscillatory features. This demonstrates that the intergalactic magnetic field constitutes the dominant astrophysical uncertainty in extracting ALP limits from GRB 221009A. Our analysis highlights the importance of realistic propagation modeling in future gamma-ray searches for ALPs.

hep-ph↗

arXiv2025

Curvature Perturbations from Higgs Modulated Reheating

In this work we investigate curvature perturbations and non-Gaussianity arising from Higgs modulated reheating in the early Universe. We employ three different methods -- the period-averaging (PA) method, the exact method, and the non-perturbative $δN$ formalism -- to compute the power spectrum and bispectrum of curvature perturbations. Our results show that the non-perturbative $δN$ method provides a reliable estimate across a wide range of reheating time and Higgs field values, including regimes where the Higgs field oscillates significantly after inflation. We find that a smaller Higgs self-coupling ($λ$) leads to a larger curvature perturbation, with the non-Gaussianity predominantly taking a local shape. This highlights the importance of considering non-perturbative effects in calculating the curvature perturbation during Higgs modulated reheating, especially for smaller values of $λ$. Our findings offer valuable insights into the dynamics of reheating and the generation of primordial perturbations in the early Universe.

astro-ph.CO↗

arXiv2025

Probing Non-Thermal Gravitinos Through Large-Scale Structure Observations

We investigate the effects of non-thermally produced dark matter on large-scale structure formation, focusing on the gravitino dark matter. Our analysis shows that large-scale structure measurements from the SDSS LRG data offer a promising approach to probing non-thermally produced gravitinos. Specifically, if gravitinos resulting from neutralino decay constitute a fraction $F_\text{dec}=0.35~(0.1)$ of the dark matter component, the data exclude bino-like neutralino with a mass $m_{χ_1^0}\lesssim 25~(11)\text{ GeV}$ at $95\%\text{ C.L.}$. Furthermore, this constraint appears to be largely independent of the gravitino mass.

hep-ph↗

arXiv2025

Probing Type II Seesaw Leptogenesis Through Lepton Flavor Violation

Lepton flavor violation (LFV) offers a powerful probe of physics beyond the Standard Model, particularly in models addressing neutrino masses and the baryon asymmetry of the universe. In this study, we investigate LFV processes within the framework of type II seesaw leptogenesis, where the Standard Model is extended by an $SU(2)_L$ triplet Higgs field. We focus on key LFV processes including $μ^+\to e^+γ$, $μ^+ \to e^+e^-e^+$, and $μ\rightarrow e$ conversion in nuclei, deriving stringent constraints on the parameter space from current experimental data. We scan the 3$σ$ range of neutrino oscillation parameters and identify the most conservative bounds consistent with existing measurements. Our results reveal that the MEG experiment currently provides the strongest constraints in the normal ordering (NO) scenario, while the SINDRUM experiment offers comparable sensitivity in the inverted ordering (IO) case. Future experiments, such as MEG II, Mu3e, Mu2e, and COMET, are predicted to significantly improve the sensitivity, testing larger regions of the parameter space. This work underscores the crucial role of LFV experiments in probing type II seesaw leptogenesis, providing an avenue to explore the connections between neutrino mass generation, baryogenesis, and inflation at experimentally accessible energy scales.

hep-ph↗

arXiv2023

Type-II Seesaw Leptogenesis along the Ridge

Type-II seesaw leptogenesis is a model that integrates inflation, baryon number asymmetry, and neutrino mass simultaneously. It employs the Affleck-Dine mechanism to generate lepton asymmetry, with the Higgs bosons serving as the inflaton. Previous studies assumed inflation to occur in a valley of the potential, employing the single-field approximation. In this work, we explore an alternative scenario for the type-II seesaw leptogenesis, where the inflation takes place along a ridge of the potential. Firstly, we conduct a comprehensive numerical calculation in the canonical scenario, where inflation occurs in a valley, confirming the effectiveness of the single-field approximation. Then, we introduce a novel scenario wherein inflation initiates along the potential's ridge and transitions to the valley in the late stages. In this case, the single-field inflation approximation is no longer valid, yet leptogenesis is still successfully achieved. We find that this scenario can generate a significant non-Gaussianity signature, offering testable predictions for future experiments.

hep-ph↗

arXiv2023

Testing type II seesaw leptogenesis at the LHC

Type II seesaw leptogenesis simultaneously explains the origin of neutrino masses, the baryon asymmetry of our universe, and the inflation. The Large Hadron Collider(LHC) provides an opportunity to directly test type II seesaw leptogenesis by looking for the predicted triplet Higgs. In this paper, we perform an analysis of the detection prospect for the triplet Higgs at the LHC through the multi-electron channels. We find that due to the contribution of $pp\to H^{\pm \pm }H^{\mp }$ process, the sensitivity of multi-electron channels searching for the doubly-charged Higgs pair production can be improved. We also investigate the $3e+ {E}^{\rm miss}_{\rm T}$ signals to probe the $pp\to H^{\pm \pm }H^{\mp }$ production and find that the future high luminosity LHC could probe a triplet Higgs around 1.2 TeV at $2σ$ level.

hep-ph↗

arXiv2022

Vacuum stability of the type II seesaw leptogenesis from inflation

Recently it has been found that introducing a triplet Higgs to the standard model could provide a feasible leptogenesis to generate the baryon asymmetry of our universe, providing that the inflation is driven by the mixing state of the triplet Higgs and SM Higgs. In this work, we survey the viable parameter space satisfying the vacuum stability and perturbativity in this model. We find that the introduction of the triplet Higgs would also ameliorate the problem of the Higgs vacuum instability. We present two representative parameter regions where the origin of neutrino masses, baryon asymmetry of the universe as well as inflation can be explained while keeping consistent with the condition of vacuum stability and perturbativity.

hep-ph↗