Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userThe $B$ Anomalies and New Physics in $b to s e^+ e^-$
175
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We investigate the implications of the latest LHCb measurement of $R_K$ for NP explanations of the $B$ anomalies. The previous data could be explained if the $b to s mu^+ mu^-$ NP is in (I) $C_{9,{rm NP}}^{mumu}$ or (II) $C_{9,{rm NP}}^{mumu} = -C_{10,{rm NP}}^{mumu}$, with scenario (I) providing a better explanation than scenario (II). This continues to hold with the new measurement of $R_K$. However, for both scenarios, this measurement leads to a slight tension of $O(1sigma)$ between separate fits to the $b to s mu^+ mu^-$ and $R_{K^{(*)}}$ data. In this paper, we investigate whether this tension can be alleviated with the addition of NP in $b to s e^+ e^-$. In particular, we examine the effect of adding such NP to scenarios (I) and (II). We find several scenarios in which this leads to improvements in the fits. $Z$ and LQ models with contributions to both $b to s mu^+ mu^-$ and $b to s e^+ e^-$ can reproduce the data, but only within scenarios based on (II). If the tension persists in future measurements, it may be necessary to consider NP models with more than one particle contributing to $b to s ell^+ ell^-$.
rate research
Read More
A search for the decays $B^0_sto e^+e^-$ and $B^0to e^+e^-$ is performed using data collected with the LHCb experiment in proton-proton collisions at center-of-mass energies of $7$, $8$ and $13,text{TeV}$, corresponding to integrated luminosities of $1$, $2$ and $2,text{fb}^{-1}$, respectively. No signal is observed. Assuming no contribution from $B^0to e^+e^-$ decays, an upper limit of $mathcal{B}(B^0_sto e^+e^-)<9.4,(11.2)times10^{-9}$ is obtained at $90,(95),%$ confidence level. If no $B^0_sto e^+e^-$ contribution is assumed, a limit of $mathcal{B}(B^0to e^+e^-)<2.5,(3.0)times10^{-9}$ is determined at $90,(95),%$ confidence level. These upper limits are more than one order of magnitude lower than the previous values.
The rare decay B to K* (to K pi) mu+ mu- is regarded as one of the crucial channels for B physics since its angular distribution gives access to many observables that offer new important tests of the Standard Model and its extensions. We point out a number of correlations among various observables which will allow a clear distinction between different New Physics (NP) scenarios. Furthermore, we discuss the decay B to K* nu anti-nu which allows for a transparent study of Z penguin effects in NP frameworks in the absence of dipole operator contributions and Higgs penguin contributions. We study all possible observables in B to K* nu anti-nu and the related b to s transitions B to K nu anti-nu and B to X_s nu anti-nu in the context of the SM and various NP models.
We report the analysis of the three-body e+e- => B B-bar pi, B B*-bar pi, and B* B*-bar pi processes, including the first observation of the Zb+-(10610) =>[B B*-bar+c.c.]+- and Zb+-(10650) => [B*B*-bar]+- transitions. We measure visible cross sections for the three-body production of sigma_vis(e+e- => [B B*-bar+c.c.]+-pi-+=(11.2+-1.0(stat.)+-1.2(syst.)) pb and sigma_vis(e+e- => [B*B*-bar]+-pi-+)=(5.61+-0.73(stat.)+-0.66(syst.)) pb and set a 90% C.L. upper limit of sigma_vis(e+e- => [BB-bar]+-pi-+)<2.1 pb. The results are based on a 121.4 1/fb data sample collected with the Belle detector at a center-of-mass energy near the Y(5S) peak.
Recently, the LHCb collaboration has reported the excesses in the $b to s ll$ processes. One of the promising candidates for new physics to explain the anomalies is the extended Standard Model (SM) with vector-like quarks and leptons. In that model, Yukawa couplings between the extra fermions and SM fermions are introduced, adding extra scalars. Then, the box diagrams involving the extra fields achieve the $b to s ll$ anomalies. It has been known that the excesses require the large Yukawa couplings of leptons, so that this kind of model can be tested by studying correlations with other observables. In this paper, we consider the extra scalar to be a dark matter (DM) candidate, and investigate DM physics as well as the flavor physics and the LHC physics. The DM relic density and the direct-detection cross section are also dominantly given by the Yukawa couplings, so that we find some explicit correlations between DM physics and the flavor physics. In particular, we find the predictions of the $b to s ll$ anomalies against the direct detection of DM.
At the present time, there are a number of measurements of $B$-decay observables that disagree with the predictions of the standard model. These discrepancies have been seen in processes governed by two types of decay: (i) $b to s mu^+ mu^-u$ and (ii) $b to c tau^- {bar u}$. In this talk, I review the experimental results, as well as the proposed new-physics explanations. We may be seeing the first signs of physics beyond the standard model.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
