Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userEffects of charged Higgs boson and QCD corrections in $bar B to D tau bar u_{tau}$
73
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We study effects of charged Higgs boson exchange in $bar B to D tau bar u_{tau}$. The Yukawa couplings of Model II of two-Higgs-doublet model, which has the same Yukawa couplings as MSSM, is considered. We evaluate the decay rate including next-to-leading QCD corrections and estimate uncertainties in the theoretical calculation. Our analysis will contribute to probe an extended Higgs sector at B factory experiments.
rate research
Read More
We evaluate long-distance electromagnetic (QED) contributions to $bar{B}{}^0 to D^+ tau^{-} bar{ u}_{tau}$ and $B^- to D^0 tau^{-} bar{ u}_{tau}$ relative to $bar{B}{}^0 to D^+ mu^{-} bar{ u}_{mu}$ and $B^- to D^0 mu^{-} bar{ u}_{mu}$, respectively, in the standard model. We point out that the QED corrections to the ratios $R(D^{+})$ and $R(D^{0})$ are not negligible, contrary to the expectation that radiative corrections are almost canceled out in the ratio of the two branching fractions. The reason is that long-distance QED corrections depend on the masses and relative velocities of the daughter particles. We find that theoretical predictions for $R(D^{+})^{tau/mu}$ and $R(D^{0})^{tau/mu}$ can be amplified by $sim4%$ and $sim3%$, respectively, for the soft-photon energy cut in range $20$-$40$ MeV.
We report the first measurement of the $tau$ lepton polarization in the decay ${bar B} rightarrow D^* tau^- {bar u_{tau}}$ as well as a new measurement of the ratio of the branching fractions $R(D^{*}) = mathcal{B}({bar B} rightarrow D^* tau^- {bar u_{tau}}) / mathcal{B}({bar B} rightarrow D^* ell^- {bar u_{ell}})$, where $ell^-$ denotes an electron or a muon, with the decays $tau^- rightarrow pi^- u_{tau}$ and $tau^- rightarrow rho^- u_{tau}$. We use the full data sample of $772 times 10^6$ $B{bar B}$ pairs accumulated with the Belle detector at the KEKB electron-positron collider. Our preliminary results, $R(D^*) = 0.276 pm 0.034{rm (stat.)} ^{+0.029} _{-0.026}{rm (syst.)}$ and $P_{tau} = -0.44 pm 0.47 {rm (stat.)} ^{+0.20} _{-0.17} {rm (syst.)}$, are consistent with the theoretical predictions of the Standard Model within $0.6$ standard deviation.
We study the exclusive semi-tauonic B decay, $bar B to D tau bar u_{tau}$, in two-Higgs-doublet models. Using recent experimental and theoretical results on hadronic form factors, we estimate theoretical uncertainties in the branching ratio. As a result, we clarify the potential sensitivity of this mode to the charged Higgs exchange. Our analysis will help to probe the charged Higgs boson at present and future B factory experiments.
We study potential New Physics effects in the $bar B to D^{(*)} tau bar u$ decays. As a particular example of New Physics models we consider the class of leptoquark models and put the constraints on the leptoquark couplings using the recently measured ratios $R(D^{(*)})=BR(bar B to D^{(*)} tau bar u)/BR(bar B to D^{(*)} mu bar u)$. For consistency, some of the constraints are compared with the ones coming from the current experimental bound on $BR(B to X_s u bar u)$. In order to discriminate various New Physics scenarios, we examine the correlations between different observables that can be measured in future.
We report the first measurement of the $tau$ lepton polarization $P_tau(D^*)$ in the decay $bar{B} rightarrow D^* tau^- bar{ u}_tau$ as well as a new measurement of the ratio of the branching fractions $R(D^{*}) = mathcal{B}(bar {B} rightarrow D^* tau^- bar{ u}_tau) / mathcal{B}(bar{B} rightarrow D^* ell^- bar{ u}_ell)$, where $ell^-$ denotes an electron or a muon, and the $tau$ is reconstructed in the modes $tau^- rightarrow pi^- u_tau$ and $tau^- rightarrow rho^- u_tau$. We use the full data sample of $772 times 10^6$ $B{bar B}$ pairs recorded with the Belle detector at the KEKB electron-positron collider. Our results, $P_tau(D^*) = -0.38 pm 0.51 {rm (stat.)} ^{+0.21}_{-0.16} {rm (syst.)}$ and $R(D^*) = 0.270 pm 0.035{rm (stat.)} ^{+0.028}_{-0.025}{rm (syst.)}$, are consistent with the theoretical predictions of 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
