We investigate the potential of high-intensity muon experiments such as MEG~II and Mu3e to uncover dark matter (DM) through the lepton-flavor-violating decay $\mu^+\to e^+\chi\bar\chi$. We describe the underlying interactions in terms of dimension-six four-fermion operators and systematically explore all allowed Lorentz structures. We show that precision measurements of the Michel spectrum can probe new-physics scales of ${\cal O}({\rm TeV})$ for DM masses above approximately $1~{\rm MeV}$. For lighter DM, whose signal is confined close to the Michel endpoint, the radiative decay $\mu^+\to e^+\chi\bar\chi\gamma$ at MEG~II opens a complementary window, with sensitivity comparable to and, in some regions, stronger than that of the non-radiative channel. Remarkably, for reheating temperatures below the tens-of-MeV scale but above the BBN bound, MEG~II and Mu3e can probe regions in which freeze-in through the very same LFV interactions accounts for the observed DM abundance.
Upcoming experiments are set to dramatically improve the search for charged lepton flavor violation, with the sensitivity to the rates of $\mu\to eee$ decay and $\mu N\to eN$ conversion expected to improve by four orders of magnitude in the near future. We study how these measurements reshape our understanding of funda...
A. Di Lecce, Majid Ekhterachian, Marko Pesut et al.· 0 citations
The rare decays $K^+\to\pi^+\nu\bar\nu$ and $K_L\to\pi^0\nu\bar\nu$ are among the most precisely predicted flavor observables, enabling determinations of the CKM matrix and its CP-violating phase, as well as providing sensitivity to new physics at scales far beyond the reach of colliders. We propose a dedicated rare-ka...
We investigate the potential of Higgs cascade decays to probe neutralino dark matter below the neutrino floor in the semi-constrained Next-to-Minimal Supersymmetric Standard Model with nonuniversal gaugino masses. We focus on lightest-neutralino masses of 65 to 100 GeV and study the process $pp\to H_2\to A_1A_1\to\gamm...
Ya-Bo Dong, Kun Wang, Hai-Jun Yang et al.· 0 citations
The mono-photon process $e^+e^- \to \gamma+\mathrm{invisible}$ at Belle II probes both invisible new states and the electroweak couplings of neutrinos. In this work, we study the process $e^+e^- \to \gamma\nu\bar{\nu}$, finding that Belle II with the full expected dataset can determine the neutrino-sensitive effective...
C. H. D. de Lima, D. McKeen, Afif Omar et al.· 0 citations
The neutrino-matter interaction cause the final flavor compositions deviating from those expected in vacuum. In this work we consider neutrinos interact with ultra-light scalar dark matters $\phi$ ($m_\phi\ll 1\,{\rm eV}$). When the neutrinos emitted from a distant source and propagate through the dark matter medium, t...
The flavor structure of the Standard Model (SM) remains one of the most compelling questions in particle physics, with the third generation being particularly intriguing due to its significantly larger masses and comparatively less precisely measured properties. These features make third-generation flavor transitions p...
Abhik Sarkar, Subhajit Kala, Amir Subba et al.· 0 citations
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