arXiv subjects

Jilberto Zamora-Saá

Publications and source records attributed to Jilberto Zamora-Saá.

3 recordsLinked to original sources

arXiv2020

Exploring CP-Violating heavy neutrino oscillations in rare tau decays at Belle II

In this work, we study the lepton number violating tau decays via two intermediate on-shell Majorana neutrinos $N_j$ into two charged pions, and a charged lepton $τ^{\pm} \to π^{\pm} N_j \to π^{\pm} π^{\pm} \ell^{\mp}$. We consider the scenario where the heavy neutrino masses are within $0.5$ GeV $\leq M_N \leq 1.5$ GeV. We evaluated the possibility to measure the modulation of the decay width along the detector length for these processes at taus factories, such as Belle II. We study some realistic conditions which could lead to the observation of this phenomenon at futures $τ$'s factories.

hep-ph↗

arXiv2018

Detection of Cosmic-Ray Ensembles with CREDO

One of the main objectives of cosmic-ray studies are precise measurements of energy and chemical composition of particles with extreme energies. Large and sophisticated detectors are used to find events seen as showers starting in the Earth's atmosphere with recorded energies larger than 100 EeV. However, a Cosmic-Ray Ensemble (CRE) developing before reaching the Earth as a bunch of correlated particles may spread over larger areas and requires an extended set of detectors to be discovered. The Cosmic-Ray Extremely Distributed Observatory (CREDO) is a solution to find such phenomena. Even simple detectors measuring the particle arrival time only are useful in this approach, as they are sufficient both to provide candidate CRE events and to determine the direction from which they are arriving.

astro-ph.IM↗

arXiv2014

CP violations in $π^{\pm}$ Meson Decay

We study the pion decays with intermediate on-shell neutrinos $N$ into two electrons and a muon, $π^{\pm} \to e^{\pm} N \to e^{\pm} e^{\pm} μ^{\mp} ν$. We investigate the branching ratios ${\rm Br}_{\pm} = [Γ(π^- \to e^- e^- μ^+ ν) \pm Γ(π^+ \to e^+e^+μ^-ν)]/Γ(π^- \to {\rm all})$ and the CP asymmetry ratio ${\cal A}_{\rm CP} = {\rm Br}_{-}/{\rm Br}_{+}$ for such decays, in the scenario with two different on-shell neutrinos. If $N$ is Dirac, only the lepton number conserving (LC) decays contribute (LC: $ν= ν_e$ or ${\bar ν}_e$); if $N$ is Majorana, both LC and lepton number violating (LV) decays contribute (LV: $ν={\bar ν}_μ$ or $ν=ν_μ$). The results show that the CP asymmetry ${\cal A}_{\rm CP}$ is in general very small, but increases and becomes $\sim 1$ when the masses of the two intermediate neutrinos get closer to each other, i.e., when their mass difference becomes comparable with their decay width, $ΔM_N \not\gg Γ_N$. The observation of CP violation in pion decays would be consistent with the existence of the well-motivated $ν$MSM model with two almost degenerate heavy neutrinos.

hep-ph↗