Related papers: Dark light shining on $B\to K^{(*)} E_{\rm miss}$
We propose a minimal UV-complete model for kinematically forbidden Dark Matter (DM) leading to a sub-GeV thermal relic. Our crucial realization is that the two-Higgs-doublet model can provide a light mediator through which the DM can…
An axion-like particle $a$ (ALP) can explain the excess of $B\rightarrow K + \text{invisible}$ events at Belle-II. However, many analyses of ALP scenarios are over-simplified. We revisit the $B\rightarrow K a$ transition rate in a popular…
We study flavor changing neutral current decays of $B$ and $K$ mesons in the dark $U(1)_D$ model, with the dark photon/dark $Z$ mass between 10 MeV and 2 GeV. Although the model provides an improved fit (compared to the standard model) to…
The surprising excess of missing-energy events far beyond all standard-model expectations in the weak decays of the charged ground-state $B^+$ meson into some charged strange meson, rather recently observed by the Belle-II experiment, may…
The study of the rare decays $B\to K^{(*)} \nu \bar\nu$ offers a window into the dynamics operating at the electroweak scale, allowing studies of the Standard Model and searches for heavy new physics. However, the analysis of these decays…
The Belle II experiment recently observed the decay $B^+ \to K^+ \nu \nu$ for the first time, with a measured value for the branching ratio of $ (2.3 \pm 0.7) \times 10^{-5}$. This result exhibits a $\sim 3\sigma$ deviation from the…
We consider $U(1)_H$ extensions of Type-I 2HDM plus a singlet scalar $\phi_H$, introducing a new Higgs doublet $H_2$ and a singlet $\phi_H$ charged under $U(1)_H$. The SM Higgs doublet $H_1$ as well as all the SM fermions and three…
Spin-1/2 inelastic dark matter (DM) models are popular among sub-GeV to GeV thermal DM scenarios due to the dominant role of co-annihilation in determining the DM relic abundance. In these models, the dark Higgs boson plays a crucial role…
There are presently several discrepancies in $b \to s \ell^+ \ell^-$ decays of $B$ mesons suggesting new physics coupling to $b$ quarks and leptons. We show that a $Z'$, with couplings to quarks and muons that can explain the $B$-decay…
If the standard electroweak gauge model is extended to include two or more Higgs doublets, there may be a neutral Higgs boson $h$ which is light (with a mass of say 10 GeV) but the $hZZ$ coupling is suppressed so that it has so far escaped…
The recent Belle II observation of $B \to K E_{\rm miss}$ challenges theoretical interpretations in terms of Standard Model neutrino final states. Instead, we consider new physics scenarios where up to two new light-invisible particles of…
Recently the Belle II Collaboration has reported a measurement of the $B^+\to K^+\nu\bar\nu$ rate that is higher than the standard-model expectation. Since the emitted neutrinos are unobserved, the excess could be due to the $B^+$ decaying…
Two of the most widely studied extensions of the Standard Model (SM) are $a)$ the addition of a new $U(1)$ symmetry to its existing gauge groups, and $b)$ the expansion of its scalar sector to incorporate a second Higgs doublet. We show…
We elucidate the recently observed discrepancy in the branching ratio of $B^{+}\rightarrow K^{+}$ +inv decay mode using a GeV scale scalar dark matter in an anomaly-free $U(1)_{B-L}$ gauge extension of the Standard Model. We constrain the…
The Belle II experiment aims to record 50 ab$^{-1}$ data with the high luminosity to be provided by the SuperKEKB asymmetric-energy electron-positron collider. The anticipated high statistics data enables us to perform studies of $B$ decays…
Inelastic dark matter models that have two dark matter particles and a massive dark photon can reproduce the observed relic dark matter density without violating cosmological limits. The mass splitting between the two dark matter particles…
In the Standard Model (SM) the branching ratio for the decay $K_L \to \nu \bar{\nu}$ into two neutrinos is helicity suppressed and predicted to be very small $ \leq O(10^{-17})$. We consider two natural extensions of the SM, such as…
The observed deviations from the Standard Model in several b -> s mu mu processes can be explained in terms of a new vector boson produced on-shell in B meson decays. A mass of 2.5-3 GeV and a total width of 10-20% allow to hide the…
In this paper, we study two Higgs doublet models with gauged U(1)_H symmetry, motivated by the excesses around 96 GeV reported by the CMS collaboration in the searches for light resonances decaying to two photons and two \tau's. In this…
The possibility of a dark sector weakly coupling to Standard Model (SM) particles through new light mediators is explored at the Belle II experiment. We present here results from three different searches, for a long-lived (pseudo)scalar…