Probing Cosmic Neutrino Background Charge via Unconventional Interferometer

If neutrinos carry non-zero electric charge, they would interact directly with photons. This would induce a phase shift along the photon path in the optical experiment. We propose a novel idea to detect this phase shift induced by cosmic neutrino background (CNB) and the photon interaction using laser interferometry experiment. We show that our setup can probe the CNB neutrino charge in the order of $10^{-18} \,e- 10^{-17}\, e$. This is quite competitive with the existing upper bound on neutrino charge from both laboratory experiments and astrophysical observations.Comment: 10 pages, 4 figure

Top Quark Rare Decays via Loop-Induced FCNC Interactions in Extended Mirror Fermion Model

Flavor changing neutral current (FCNC) interactions for a top quark $t$ decays into $Xq$ with $X$ represents a neutral gauge or Higgs boson, and $q$ a up- or charm-quark are highly suppressed in the Standard Model (SM) due to the Glashow-Iliopoulos-Miami mechanism. Whilst current limits on the branching ratios of these processes have been established at the order of $10^{-4}$ from the Large Hadron Collider experiments, SM predictions are at least nine orders of magnitude below. In this work, we study some of these FCNC processes in the context of an extended mirror fermion model, originally proposed to implement the electroweak scale seesaw mechanism for non-sterile right-handed neutrinos. We show that one can probe the process $t \to Zc$ for a wide range of parameter space with branching ratios varying from $10^{-6}$ to $10^{-8}$, comparable with various new physics models including the general two Higgs doublet model with or without flavor violations at tree level, minimal supersymmetric standard model with or without $R$-parity, and extra dimension model.Comment: 30 pages, 8 figures, 2 tables and 1 appendix. Version to appear in NP

Light Dark Matter Scattering in Gravitational Wave Detectors

We present prospects for discovering dark matter scattering in gravitational wave detectors. The focus of this work is on light, particle dark matter with masses below 1 GeV/c$^{2}$. We investigate how a potential signal compares to typical backgrounds like thermal and quantum noise, first in a simple toy model and then using KAGRA as a realistic example. That shows that for a discovery much lighter and cooler mirrors would be needed. We also give some brief comments on space-based experiments and future atomic interferometers.Comment: 26 pages, 5 figures; version published in Eur. Phys. J.

Millicharge Dark Matter Detection with Mach-Zehnder Interferometer

If the dark sector exists and communicates with Standard Model through the $U(1)$ mixing, it is possible that electromagnetism would have influence on matter fields in dark sector, so-called millicharge particles (mCPs). Furthermore, the highest mCPs could be dark matter particles. Recently it has been shown that the mCPs would be slowed down and captured by the earth. As a result, the number density of accumulated mCPs underground is enhanced by several orders of magnitude as compared to that of dark matter in our solar system. In this study, we propose to use the Mach-Zehnder (MZ) laser interferometer to detect earth bound mCPs through the detection of phase shifts of photons. We show that, for mass of mCPs lager than $1$ GeV, the sensitivity of probing the mixing parameter $\epsilon$ could reach as low as $10^{-11}$ if number density is larger than $1~\rm{cm^{-3}}$.Comment: 12 pages, 4 figure

Lepton Flavor Violating Decays of Neutral Higgses in Extended Mirror Fermion Model

We perform the one-loop induced charged lepton flavor violating decays of the neutral Higgses in an extended mirror fermion model with non-sterile electroweak-scale right-handed neutrinos and a horizontal $A_4$ symmetry in the lepton sector. We demonstrate that for the 125 GeV scalar $h$ there is tension between the recent LHC result ${\cal B}(h \to \tau \mu) \sim$ 1% and the stringent limits on the rare processes $\mu \to e \gamma$ and $\tau \to (\mu$ or $e) \gamma$ from low energy experiments.Comment: 23 pages, 3 figures. Added some of referenc

Exploring Dark Photon via Sub-Frequency Laser Search in Gravitational Wave Detectors

We propose a novel idea to detect dark photon in the gravitational wave (GW) experiments. Our setups are capable to perform the whole process of dark photon production, its decay products, and new physics signal discovery. This "mini LHC" is inspired from the recent idea of the dark photon detection using the laser light in light shinning through the wall (LSW) experiments such as ALPS II. Taking the sub-frequency light emitted from the laser source as the new physics signal, we show that the sensitivity of our proposal is two order magnitude better than the original idea in the LSW studies.Comment: 5 figures, 1 tabl

Effects of new heavy fermions on complex scalar dark matter phenomenology in gauged two Higgs doublet model

We study the inclusion of new heavy fermions on complex scalar dark matter (DM) phenomenology within gauged two Higgs doublet model (G2HDM). We find that for DM mass above 1 TeV, heavy quarks coannihilations into the Standard Model (SM) quarks and gluons dominate the thermally-averaged cross section relevant for the relic abundance of complex scalar DM. We demonstrate that the effects of QCD Sommerfeld correction as well as QCD bound state formation in determining the DM relic density are negligible. We show that the allowed parameter space is significantly constrained by the current PLANCK relic density data as well as XENON1T limit appropriate for DM direct search