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R. J. Oakes

Publications and source records attributed to R. J. Oakes.

14 recordsLinked to original sources
arXiv2008

B meson Dileptonic Decays in NMSSM with a Light CP-odd Higgs Boson

In the next-to-minimal supersymmetric model (NMSSM) a light CP-odd Higgs boson is so far allowed by current experiments, which, together with a large tan-beta, may greatly enhance the rare dileptonic decays B-> X_s l^+ l^- and B_s-> l^+ l^- gamma. We examine these decays paying special attention to the new operator allowed by the light CP-odd Higgs boson. We find that in the parameter space allowed by current experiments like LEP II and b-> s gamma, the branching ratios of these rare decays can be greatly enhanced and thus the existing experimental data on B-> X_s mu^+ mu^- can further stringently constrain the parameter space (especially the region with a super-light CP-odd Higgs boson and large tan-beta). In the surviving parameter space we give the predictions for other dileptonic decay branching ratios and also show the results for the forward-backward asymmetry.

hep-ph↗
arXiv2002

CP violating phase $γ$ and the partial widths asymmetry in $B^- \to π^+ π^- K^-$ and $B^- \to K^+ K^- K^-$ decays

Motivated by recent Belle measurement of the branching ratios $B^- \to π^+ π^- K^-$ and $B^- \to K^+ K^- K^-$ and $B^\pm \to χ_{c0} K^\pm$, we investigate the CP violating asymmetry in the partial widths for the decays $B^- \to π^+ π^- K^-$ and $B^- \to K^+ K^- K^-$, which results from the interference of the nonresonant decay amplitude with the resonant amplitude $B^\pm \to χ_{c0} K^\pm $ $ \toπ^+ π^- K^\pm $ and $B^\pm \to χ_{c0} K^\pm$ $ \to K^+ K^- K^-$. By taking $γ\simeq 58^o$ we predict that the partial widths asymmetry is reaching 10% for the $B^- \to π^+ π^- K^-$ decay and 16% for the $B^- \to K^+ K^- K^-$decay.

hep-ph↗
arXiv1998

The penguin operators in nonresonant $B^- \to M \bar M π^-$ $(M =π^-, K^-, K^0)$ decays

We investigate the contributions coming from the penguin operators in the nonresonant $B^- \to M \bar M π^-$ ($M =π^-, K^-, K^0$) decays. The effective Wilson coefficients of the the strong penguin operators $O_{4,6}$ are found to be relatively larger. We calculate the contributions arising from the $O_4$ and $O_6$ operators in the nonresonant decays $B^- \to M \bar Mπ^-$ ($M = π^-, K^-, \bar K^0$) using a model combining heavy quark symmetry and the chiral symmetry, developed previously. We find that the forbidden nonresonant $B^- \to K^0 \bar K^0 π^-$ decay occurs through the strong penguin operators. These penguin contributions affect the branching ratios for $B^- \to M \bar Mπ^-$ ($M = π^-, K^-$) by only a few percent. The branching ratio for $B^- \to K^0 \bar K^0 π^-$ is estimated to be of the order $ 10^{-6}$.

hep-ph↗
arXiv1998

The CP violating asymmetry in $B^{\pm} \to M {\bar M} π^{\pm}$ decays

We analyze the asymmetry in the partial widths for the decays $B^{\pm} \to M {\bar M} π^{\pm}$ ($ M = π^+, K ^+, π^0, η$), which results from the interference of the nonresonant decay amplitude with the resonant amplitude for $B^{\pm} \to χ_{c0} π^{\pm} $ followed by the decay $χ_{c0} \to M {\bar M} $. The CP violating phase $γ$ can be extracted from the measured asymmetry. We find that the partial width asymmetry for $B^\pm \to π^+ π^- π^\pm$ is about $0.33~sin γ$, and about $0.45~ sin γ$ for $B^\pm \to K^+ K^-π^\pm$, while it is somewhat smaller for $B^\pm \to π^0 π^0 π^\pm$ and $B^\pm \to ηηπ^\pm$. Potential sources of uncertainties in these results, primarily coming from poorly known input parameters, are discussed.

hep-ph↗
arXiv1998

Signal for CP violation in $B^{\pm} \to P {\bar P} π^{\pm}$ decays

We analyze the partial rate asymmetry in $B^{\pm} \to P {\bar P} π^{\pm}$ decays ($ P = π^+, K ^+, π^0, η$) which results from the interference of the nonresonant decay amplitude and the resonant amplitude for $B^{\pm} \to χ_{c0} π^{\pm} $ followed by the decay $χ_{c0} \to P {\bar P} $. The CP violating phase $γ$ can be extracted from the measured asymmetry. We find that the partial rate asymmetry for $B^\pm \to π^+ π^- π^\pm$ is $0.33~sin γ$, while for $B^\pm \to K^+ K^-π^\pm$ it amounts $0.45~ sin γ$.

hep-ph↗
arXiv1998

Resonant and nonresonant D+ -> K- pi+ l+ nu(l) semileptonic decays

We analyse the semileptonic decay D+ -> K- pi+ l+ nu(l) using an effective Lagrangian developed previously to describe the decays D -> P l nu(l) and D -> V l nu(l). Light vector mesons are included in the model which combines the heavy quark effective Lagrangian and chiral perturbation theory approach. The nonresonant and resonant contributions are compared. With no new parameters the model correctly reproduces the measured ratio Gamma(nres)/Gamma(nres + res). We also present useful nonresonant decay distributions. Finally, a similar model, but with a modified current which satisfies the soft pion theorems at the expense of introducing another parameter, is analyzed and the results of the models are compared.

hep-ph↗
arXiv1997

Probing top quark decay into light stop in the supersymmetric standard model at the upgraded Tevatron

We investigate the possibility of observing the exotic decay mode of the top quark into the lightest stop ($\tilde t_1$) and neutralino ($\tildeχ^0_1$) in the minimal supersymmetric standard model with R-parity at the upgraded Tevatron. First we determine the allowed range for the branching fraction $B(t\to \tilde t_1 \tildeχ^0_1)$ in the region of parameter space allowed by the $R_b$ data and the CDF $eeγγ+{\large \not} E_T$ event, and then consider all possible backgrounds and investigate the possibility of observing this final state at the Tevatron. We find that this final state is unobservable at Run 1. However, Run 2 can provide significant information on this new decay mode of the top quark: either discover it, or establish a strong constraint on the masses of $\tilde t_1$ and $\tildeχ^0_1$ given approximately by $M_{\tilde χ^0_1} > M_{\tilde t_1} - 6$ GeV.

hep-ph↗
arXiv1997

Single top quark production as a probe of R-parity-violating SUSY at pp and p\bar p colliders

We investigate the ability of single top quark production via qq'-> squark->tb and q \bar q'->slepton->t\bar b at the LHC and Tevatron to probe the strength of R-parity violating couplings in the minimal supersymmetric model. We found that given the existing bounds on R-parity violating couplings, single top quark production may be greatly enhanced over that predicted by the standard model, and that both colliders can either discover R-parity violating SUSY or set strong constraints on the relevant R-parity violating couplings. We further found that the LHC is much more powerful than the Tevatron in probing the squark couplings, but the two colliders have comparable sensitivity for the slepton couplings.

hep-ph↗
arXiv1995

An effective model for charmed meson semileptonic decays

We analyze charm meson semileptonic decays using the measured ratios $Γ_L/Γ_T$ and $Γ_{+}/Γ_{-}$ from $D\to {\bar K}^{*}$ and the branching ratios for $D \to {\bar K}^{*}$ and $D \to {\bar K}$. First we introduce the light vector mesons in a model which combines the heavy quark effective Lagrangian and the chiral perturbation approach. We propose a method which predicts the behavior of the form factors. Using the available experimental data we determine the values of some model parameters and reproduce the observed branching ratios for $D_{s} \to Φ$, $D_{s} \to (η+ η^{\prime})$ and $D \to π$. We make predictions for the yet unmeasured branching ratios and polarization observables.

hep-ph↗
arXiv1995

$c\to u γ$ in Cabibbo suppressed D meson radiative weak decays

We investigate Cabibbo suppressed $D^{0}$, $D^{+}$ and $D^{+}_{s}$ radiative weak decays in order to find the best mode to test $c\to u γ$ decay. Combining heavy quark effective theory and the chiral Lagrangian approach we determine the decay widths. We calculate $Γ(D^{0}\to ρ^{0}/ωγ)/ Γ(D^{0}\to {\bar K}^{*0} γ)$ previously proposed to search for possible New Physics. However, we notice that there are large, unknown, corrections within the Standard Model. We propose a better alternative, the ratio $Γ(D_{s}^{+}\to K^{*+} γ)/ Γ(D_{s}^{+}\to ρ^{+} γ)$, and show that it is less sensitive to the Standard Model.

hep-ph↗
arXiv1995

Charm meson radiative decays

Combining heavy quark effective theory and the chiral Lagrangian approach we investigate D meson radiative decays. First, we reanalyse $D^{*} \rightarrow D γ$ decays using heavy quark spin symmetry, chiral symmetry Lagrangian, but including also the light vector mesons. Then, we calculate branching ratios $D \rightarrow V γ$. We make some comments on the Cabbibo suppressed decays $D \to ρ/ ωγ$ and the branching ratios of $D \rightarrow P P γ$ decays.

hep-ph↗
arXiv1994

Vector and pseudoscalar charm meson radiative decays

Combining heavy quark effective theory and the chiral Lagrangian approach we investigate radiative decays of pseudoscalar $D$ mesons. We first reanalyse $D^{*} \rightarrow D γ$ decays within the effective Lagrangian approach using heavy quark spin symmetry, chiral symmetry Lagrangian, but including also the light vector mesons. We then investigate $D \rightarrow V γ$ decays and calculate the $D^0 \rightarrow \bar{K}^{*0} γ$ and $D^{s+} \rightarrow ρ^+ γ$ partial widths and branching ratios.

hep-ph↗