Using the $B_s$ meson wave function extracted from non-leptonic $B_s$ decays, we reevaluate the rare decays $B_s\to \ell^+\ell^- γ, (\ell=e,μ)$ in the standard model, including two kinds of contributions from magnetic-penguin operator with virtual and real photon. We find that the contributions from magnetic-penguin operator $b\to sγ$ with real photon to the exclusive decays, which is regarded as to be negligible in previous literatures, are large, and the branchings of $B_s\to \ell^+\ell^-γ$ are nearly enhanced by a factor 2. With the predicted branching ratios at order of $10^{-8}$, it is expected that the radiative dileptonic decays will be detected in the LHC-b and B factories in near future.
The sensitivity of the $B \to πK$ mode to electroweak penguins and the recent experimental data for the $B \to ππ$, $πK$ modes has given rise to what is known as the ``$B \to πK$ puzzle''. Recently it has been observed that this {\sl puzzle} can be resolved by considering the new physics which can enter via $Z^0$ penguins. In this note we analyze the effect of this enhanced $Z^0$ penguins on the lepton polarization asymmetries of $b \to s \ell^+ \ell^-$.
We investigate the rare electroweak penguin transition $b \to s \ell^+ \ell^-$ though angular analyses in baryonic $b$-decays. Instead of performing likelihood fits, that might suffer from ambiguity issues, we employ the moments technique, which is a simple counting experiment. The method is known to be robust under low statistics conditions and avoids the ambiguity problem by construction. We provide the full set of 32 orthonormal moments for $Λ^0_b\to p h^-\ell^+\ell^-$, where $h\in\{π,K\}$, for a polarized $Λ^0_b$ and the dihadron system $[ph]$ being in a spin-1/2 state.
Rare B decays of the type $b \to s~\ell^+\ell^-(ν\barν)$ are analyzed in a generic scenario where New Physics effects enter predominantly via $Z$ penguin contributions. We show that this possibility is both phenomenologically allowed and well motivated on theoretical grounds. The important role played in this context by the lepton forward-backward asymmetry in $B\to K^*\ell^+\ell^-$ is emphasized.
We report on recent progress in the field of nonlocal (so-called resolved) contributions to the inclusive penguin decays which presently belong to the largest uncertainties in these inclusive decay modes. There is still a very large scale and a large charm mass dependence in the present leading order results which can in the future be decreased by including the $α_s$ corrections.
A useful inequality is obtained if charmless strange B decays are assumed to be dominated by the gluonic penguin diagram and the tree diagram contribution is small but not negligible. The penguin-tree interference contribution which is linear in the tree amplitude is included but the direct tree contribution which is quadratic is neglected.
We study Lambda_{QCD}/m_B corrections to factorization in B -> K pi decays. First, we analyze these decay channels within factorization, showing that, irrespectively of the value of gamma, it is not possible to reproduce the experimental data. Then, we discuss Lambda_{QCD}/m_B corrections to these processes, and argue that there is a class of doubly Cabibbo enhanced non-factorizable contributions, usually called charming penguins, that cannot be neglected. Including these corrections, we obtain an excellent agreement with experimental data. Furthermore, contrary to what is obtained with factor…
Constraints placed on physics beyond the Standard Model from the recent CLEO observation of the inclusive decay $B\to X_sγ$ are summarized. Further searches for new physics using the process $B\to X_s\ell^+\ell^-$ are discussed. {Presented at the {\it International Workshop on B Physics: Physics Beyond the Standard Model at the B Factory}, Nagoya, Japan, October 26-28, 1994}
For the exploration of flavour physics, b -> d penguin processes are an important aspect, with the prominent example of \bar B^0_d -> K^0 \bar K^0. We recently derived lower bounds for the CP-averaged branching ratio of this channel in the Standard Model; they were found to be very close to the corresponding experimental upper limits, thereby suggesting that \bar B^0_d -> K^0 \bar K^0 should soon be observed. In fact, the BaBar collaboration subsequently announced the first signals of this transition. Here we point out that it is also possible to derive lower bounds for \bar B -> ργdecays, whi…
The pure annihilation type decays $B^0_d\toϕγ$ and $B_s\toργ$ receive only color suppressed penguin contributions with a very small branching ratio in the standard model. When we include the previously neglected electromagnetic dipole operator, the branching ratios can be enhanced one order magnitude larger than previous study using QCD factorization approach. That is ${\cal BR}(\bar B^0_d\toϕγ)\simeq 1 \times 10^{-11}$ and ${\cal BR}(B_s\toργ) \sim (6-16)\times 10^{-10}$. The new effect can also give a large contribution, of order $10^{-9}$, to transverse polarization of $B\toϕρ$ and $B\to ωϕ…
A useful inequality is obtained if charmless strange B decays are assumed to be dominated by a $ΔI = 0$ transition like that from the gluonic penguin diagram and the contributions of all other diagrams including the tree, electroweak penguin and annihilation diagrams are small but not negligible. The interference contributions which are linear in these other amplitudes are included but the direct contributions which are quadratic are neglected.
We study the effects of electroweak penguin (EWP) amplitudes in $B$ meson decays into two charmless pseudoscalars in the approximation of retaining only the dominant EWP operators $Q_9$ and $Q_{10}$. Using flavor SU(3) symmetry, we derive a set of model-independent relations between EWP contributions and tree-level decay amplitudes one of which was noted recently by Neubert and Rosner. Two new applications of these relations are demonstrated in which uncertainties due to EWP corrections are eliminated in order to determine a weak phase. Whereas the weak angle $α$ can be obtained from $B\toππ$ …
The LHCb experiment has very recently presented new results on Lepton Universality Violation (LUV) in $B \to K^{(*)} \ell^+ \ell^-$ decays involving $K_S$ in the final state, which strengthens the recent evidence of LUV obtained in $B^+ \to K^{+} \ell^+ \ell^-$ decays and the previous measurements of $B \to K^{*0} \ell^+ \ell^-$. While LUV observables in the Standard Model are theoretically clean, their predictions in New Physics scenarios are sensitive to the details of the hadronic dynamics, and in particular of the charming penguin contribution. In this work, we show how a conservative trea…
We calculate the enhancements to the inclusive charmless decays of b quark, $b \to s g, s q\bar{q}, sgg$, from gluon penguin diagrams induced by the charged and neutral Higgs bosons $(H^{\pm}, h^0, H^0$, and A^0) in the Two-Higgs-Doublet Model with flavor-changing couplings. Within the considered parameter space, the new contributions from charged Higgs boson are dominant. After including the new contributions, the branching ratio $BR(b \to sg)$ (q^2 =0) can be increased form $\sim 0.2%$ in the standard model to 4.4% and 2.6% in the two-Higgs-doublet model for $m_{H^+}=100$ and 200 GeV, respec…
We study the effect of a sequential fourth generation on b\to s gamma, B_s mixing, B\to K^{(*)}\ell^+\ell^-, X_s\ell^+\ell^- and ϕK_S, taking into account the presence of a new CP phase in quark mixing. We find that the effects via electromagnetic and strong penguins, such as in b\to s gamma or CP violation in B\to ϕK_S, are rather mild, but impact via box or Z penguins is quite significant. Not only can one have much larger than expected B_s mixing, even if it is measured near the present limit, mixing dependent CP violation could become maximal. For electroweak penguin modes, the fourth gene…
We report on new results on $B \to K^* γ$ and recent studies on $B \to K^* \ell^+ \ell^-$ and $B \to h ν\barν$ at Belle at KEKB accelerator. All the analyses used full data sample of 711~fb${}^{-1}$ taken on $Υ(4S)$ resonance.
We report on the measurement of the decay $B\to K^{\star}γ$, lepton-flavor dependent angular analysis of the decay $B\to K^{\star}\ell\ell$, and search for the decays $B\to hνν$. All these analyses are performed on the 711 $fb^{-1}$ data sample recorded by the Belle detector at the $Υ(4S)$ resonance.
Weak radiative baryonic B decays $\bar B\to B_1\bar B_2γ$ mediated by the electromagnetic penguin process $b\to sγ$ are re-examined within the framework of the pole model. The meson pole contribution that has been neglected before is taken into account in this work. It is found that the intermediate $K^*$ contribution dominates in the $Σ\bar pγ$ mode and is comparable to the baryon pole effect in $Λ\bar pγ$ and $Ξ\barΛγ$ modes. The branching ratios for $B^-\toΛ\bar pγ$ and $B^-\toΞ^0\barΣ^-γ$ are of order $2.6\times 10^{-6}$ and $6\times 10^{-7}$, respectively. The threshold enhancement effect…
The theoretical precision of the measurement of the $B^0_{d,s}$-$\bar B^0_{d,s}$ mixing phases $ϕ_{d,s}$ through the benchmark decays $B^0_d\to J/ψK_S$, $B^0_s\to J/ψϕ$ and $B^0_s\to J/ψf_0(980)$ is limited by doubly Cabibbo-suppressed penguin topologies which are usually neglected. However, the search for New-Physics effects in the quark-flavor sector has entered a territory where these effects have to be taken into account, which will be particularly relevant for the LHCb upgrade era. Thanks to their non-perturbative nature, the penguin corrections cannot be calculated but have rather to be …
Theoretical framework for lattice QCD computations of $B\to K \ell^+ \ell^-$ and $\bar{B}_s\to \ell^+\ell^- γ$ decays rates, including contributions from charming penguin diagrams
Università di Roma “Tor Vergata”（罗马托尔维加塔大学）；INFN, Sezione di Roma Tre（意大利国家核物理研究所罗马三分所）；INFN, Sezione di Roma（意大利国家核物理研究所罗马分所）；Università di Roma La Sapienza（罗马第一大学）；University of Southampton（南安普顿大学）
The $Z'$-gauge boson in an $U(1)_{L_μ-L_τ}$ gauge symmetry has two interesting features: one is its vector couplings to the charged leptons, and the other is the decoupling from the electron. Based on these properties, we investigate the feasibility to simultaneously resolve the $R_{K^{(*)}} = BR(B\to K^{(*)} μ^+ μ^-)/BR(B\to K^{(*)} e^+ e^-)$ and $R_{D^{(*)}} = BR(\bar B\to D^{(*)} τ\barν_τ)/BR(\bar B\to D^{(*)} \ell \barν_\ell)$ anomalies in an $U(1)_{L_μ-L_τ}$ model, where the former is expected to arise from the $Z'$-penguin-induced $b\to s μ^+ μ^-$ process and the latter from the tree-lev…
Observation of CP violation in $B^o\to K^\pmπ^{\mp}$ decays and its absence in $B^+\to K^+π^o$ decays are explained in new improved data analysis of more precise $B\to Kπ$ data. Success of the "Lipkin Sum Rule" indicates that four $B\tow Kπ$ branching ratios are determined by three parameters, the penguin diagram $P$ and two interference terms $P\cdot T$ and $P\cdot S$ between the dominant penguin and two tree diagrams; the color-favored and color suppressed diagrams. Previous analyzes confirmed the model with errors leaving values of interference terms less that two standard deviations from z…
$B$-meson decays involving radiative and electroweak penguin processes are sensitive probes to new physics beyond the standard model. The Belle experiment recently reported measurements of the inclusive radiative decay $B \to X^{}_{s} γ$, and exclusive radiative decays $B \to K^{\ast} γ$ and $B \to K^{0}_{S} ηγ$. A lepton-flavor dependent measurements of angular observables for the decays $B \to K^{\ast} \ell \ell$ by Belle hinted at possible deviation from lepton-flavor-universality. Any departure from lepton flavor universality is essentially accompanied by lepton flavor violation. Recently,…
We derive and solve the renormalisation-group (RG) equation of the shape function $g_{17}(ω,ω_1;μ)$, which appears at subleading power in the factorization of the inclusive decays $\bar{B} \to X_s γ$ and $\bar B \to X_s \ell^+\ell^-$. Our results provide the first ingredient for a next-to-leading order analysis of the respective resolved-photon ${Q}^{c}_{1} - {Q}_{7γ}$ interference contribution, whose current uncertainties are among the largest ones in both inclusive penguin modes. As a by-product of our study, we find that the analytic properties of the soft anomalous dimension as well as the…
The fact that the measured B to ππ, πK branching ratios exhibit puzzling patterns has received a lot of attention in the literature and motivated the formulation of a series of new physics scenarios with enhanced Z-penguins. In this work, we analyze the effect of such an enhancement on the lepton polarization asymmetries of B_s to γ\ell^+ \ell^- decays by applying the results of a specific scenario for the solution of ``B to πK puzzle''.
Under the framework of soft-collinear effective theory, we analyze the charmless $B\to VV$ decays in a global way at leading power in $1/m_b$ and leading order in $α_s$ with $V$ denoting a light vector meson. In the flavor SU(3) symmetry, decay amplitudes for the 28 decay modes are expressed in terms of 8 nonperturbative parameters. With 35 experimental results, we fit these 8 nonperturbative parameters. Annihilation contributions are neglected due to power suppression in the $m_b\to \infty$ limit, so we include in the fit the nonperturbative charm penguins, which will play an important role i…
The semileptonic decays $\bar{B}\to D(D^*)π\ell\barν$ are analyzed by heavy quark and chiral symmetries. The branching ratio is of order of a few percent for $\dpi$, but it is much smaller for $\dstar$, of order $10^{-4}-10^{-5}$. The decay mode $B^-\to D^+π^-e^-\barν_e$ provides a nice place for extracting the $D^*Dπ$ coupling constant from the semileptonic decays of a $\bar{B}$ meson. Two types of weak radiative decays of $\bar{B}$ mesons and bottom baryons are studied. The decay $Λ_b^0\to Λ^0γ$ receives the electromagnetic penguin $b\to sγ$ contribution and has a branching ratio of order $2…
We argue that the longitudinal lepton polarization and the forward-backward asymmetries in exclusive $B\to (K,K^*)\ell^+\ell^-$ decays are largely unaffected by the theoretical uncertainties in the long-distance contributions both induced by the long-range charming penguins in the $\ell^+\ell^-$ channel and those in the meson channels encoded in the meson transition form factors, and are mainly determined by the short-distance Wilson coefficients at the low-energy scale $μ\simeq m_b$. Thus, the above mentioned asymmetries provide a powerful probe of the Standard Model and its extensions.
We briefly review the status of rare radiative and semileptonic $b \to s (γ, \ell^+ \ell^-)$, ($\ell=e,μ$) decays. We discuss possible signatures of new physics in these modes and emphazise the role of the exclusive channels. In particular, measurements of the Forward-Backward asymmetry in $B \to K^* \ell^+ \ell^-$ decays and its zero provide a clean test of the Standard Model, complementary to studies in $b \to s γ$ decays. Further, the Forward-Backward CP asymmetry in $B \to K^* \ell^+ \ell^-$ decays is sensitive to possible non-standard sources of CP violation mediated by flavor changing ne…
In view of the importance of the nonperturbative resolved contributions for the overall uncertainties of the two inclusive penguin decays $\bar B \to X_s γ$ and $\bar B \to X_{s,d} \ell^+\ell^-$ we reanalyse these contributions using new estimates of moments of the subleading shape functions and of other input parameters. Within a systematic approach we find a significant reduction of the nonperturbative uncertainties in the inclusive decay $\bar B \to X_{s,d} \ell^+\ell^-$, but a much less pronounced reduction in the inclusive decay $\bar B \to X_s γ$ compared to a recent analysis on the reso…
The $B\to a_1 \ell^+ \ell^-$ decays occur by the electroweak penguin and box diagrams which can be performed through the flavor changing neutral current (FCNC). We calculate the form factors of the FCNC $B \to a_1$ transitions in the light--cone sum rules approach, up to twist--4 distribution amplitudes of the axial vector meson $a_1$. Forward--backward asymmetry, as well as branching ratios of $B\to a_1\ell^{+}\ell^{-}$, and $B\to a_1 γ$ decays are considered. A comparison is also made between our results and the predictions of other methods.
Rare decays of heavy-flavoured particles provide an ideal laboratory to look for deviations from the Standard Model, and explore energy regimes beyond the LHC reach. Decays proceeding via electroweak penguin diagrams are excellent probes to search for New Physics, and $b \to s \ell^{+}\ell^{-}$ processes are particularly interesting since they give access to many observables such as branching fractions, asymmetries and angular observables. Recent results from the LHCb experiment are reviewed.
Leptonic decays of $B$-mesons are theoretically very clean probes for testing the Standard Model (SM) and possible physics beyond it. Amongst the various leptonic decays of the $B$-meson, the pure dileptonic decay $B \to \ell^+ \ell^-$ is very important as this mode is helicity suppressed in the SM but can be substantially enhanced in some of the models beyond the SM, such as supersymmetric (SUSY) theories and the two Higgs doublet model (2HDM). Although the purely dileptonic decay mode is helicity suppressed in the SM its associated mode $B \to \ell^+ \ell^- γ$ does not have the same suppress…
We discuss two models with 1 extra CP phase in $b\leftrightarrow s$ transition. The CP phase $\arg (V_{t^\prime s}V_{t^\prime b})$ with fourth generations, previously ignored, could impact on $b\to s\ell^+\ell^-$, $Δm_{B_s}$ and $\sin2Φ_{B_s}$, but does not affect EM and strong penguins. With SUSY at TeV scale, a right-handed ``$\widetilde{sb}_{1}$'' squark can be driven light by flavor mixing. It does not affect $b\to s\ell^+\ell^-$, but can generate $S_{ϕK_S} < 0$ while giving $S_{η^\prime K_S} \sim \sin2Φ_{B_d} \cong0.74$. $B_s$ mixing and $\sin2Φ_{B_s}$ would likely be large, and $S_{K_Sπ^…
We scrutinize the penguin dominated $ B_s \to K^+ K^-$ decay mode involving $b \to s$ quark level transition in family non-universal $Z^ \prime$ and vector-like down quark model. There is discrepancy in the standard model branching ratio value of this mode with the experimental results reported by Belle, CDF and LHCb Collaborations. Additionally, the measured values of CP-violating asymmetries $ C_{K^+K^-}$ and $ S_{K^+K^-}$ deviate from the SM results. We constrain the new parameter space by using the existing experimental limits on leptonic $ B_s\to \ell \ell$ ($\ell = e, μ, τ$) processes. W…
We analyze the contributions to rare kaon decays mediated by flavor-changing Z-penguin diagrams in a generic low-energy supersymmetric extension of the Standard Model. In order to perform a model-independent analysis we expand the squark mass matrices around the diagonal, following the so called mass-insertion approximation. We argue that in the present case it is necessary to go up to the second order in this expansion to take into account all possible large effects. The current bounds on such second-order term, which was neglected in previous analyses, are discussed in detail and the corresp…
The rare decays $B\to K^{(*)}\ell^+\ell^-$, $B\to K^{(*)}ν\barν$ and $B_s\toμ^+μ^-$ are analyzed in a generic scenario where New Physics effects enter predominantly via $Z$ penguin contributions. We show that this possibility is well motivated on theoretical grounds, as the $\bar sbZ$ vertex is particularly susceptible to non-standard dynamics. In addition, such a framework is also interesting phenomenologically since the $\bar sbZ$ coupling is rather poorly constrained by present data. The characteristic features of this scenario for the relevant decay rates and distributions are investigated…
The electroweak sector of the Standard Model contains three generations of charged leptons $\ell^-\in\{e^-,μ^-,τ^-\}$ as exact replicas of each other, except for their Yukawa couplings to the Higgs that determine their masses. The Yukawas, and thereby, the masses, are not predicted but are parameters in the theory. A basic tenet in the formalism, known as lepton universality, is equality of the couplings to the electroweak gauge bosons $\{γ, Z, W^-\}$ among all three generations, and has mostly stood the test of time. However, precision tests in $B$ decays have recently posed serious challenge…
Non-leptonic $B$ decays into charmless final states offer an important laboratory to study CP violation and the dynamics of strong interactions. Particularly interesting are $B^0_s\to K^-K^+$ and $B^0_d\toπ^-π^+$ decays, which are related by the $U$-spin symmetry of strong interactions, and allow for the extraction of CP-violating phases and tests of the Standard Model. The theoretical precision is limited by $U$-spin-breaking corrections and innovative methods are needed in view of the impressive future experimental precision expected in the era of Belle II and the LHCb upgrade. We have recen…
The decays $B_d^0\rightarrow D_d^-D_d^+$ and $B_s^0\rightarrow D_s^-D_s^+$ probe the CP-violating mixing phases $ϕ_d$ and $ϕ_s$, respectively. The theoretical uncertainty of the corresponding determinations is limited by contributions from penguin topologies, which can be included with the help of the $U$-spin symmetry of the strong interaction. We analyse the currently available data for $B^0_{d,s}\rightarrow D_{d,s}^-D_{d,s}^+$ decays and those with similar dynamics to constrain the involved non-perturbative parameters. Using further information from semileptonic $B_d^0\rightarrow D_d^-\ell^…
We present the differential rates for exclusive $\Bbar\to X \ell_1 \ell_2$, where $\ell_1$ is a charged massless lepton and $\ell_2$ is a charged or neutral massless lepton, and $X$ is a mesonic system up to spin 2. The cases of interest are semileptonic (SL) $\Bbar\to \xcu\ellm \barnuell$ decays, and $\Bbar \to X_s \ellm \ellp$ where the the di-lepton can be $c \bar{c}$ resonances or non-resonant electroweak penguins (EWP). We consider helicity amplitudes having non-zero relative phases that can be potential new sources for CP-violation. Our motivations for these additional phases include a c…
We study the effects of the identical leptons in the final state of the $B^+\to \ell^+ \ell^- \ell^+\barν_{\ell}$ decay. The amplitude of the process is described by the same form factors as the amplitude of the ${B\to \ell \ell \ell'\barν'_{\ell}}$ decay for non-identical leptons in the final state. However, the differential distributions are strongly different, as the ${B^+\to \ell^+ \ell^- \ell^+\barν_{\ell}}$ amplitude contains both the direct ($M_a$) and the exchange ($M_b$) diagrams. We calculate a number of the differential distirbutions. In particular, we propose an interesting observa…
Direct CP violation in B^0-> K^+π^- decay has emerged at -10% level, but the asymmetry in B^+ -> K^+π^0 mode is consistent with zero. This difference points towards possible New Physics in the electroweak penguin operator. We point out that a sequential fourth generation, with sizable V^*_{t's}V_{t'b} and near maximal phase, could be a natural cause. We use the perturbative QCD factorization approach for B-> Kπamplitudes. While the B^0-> K^+π^- mode is insensitive to t', we critically compare t' effects on direct CP violation in B^+ -> K^+π^0 with b-> s\ell^+\ell^- and B_s mixing. If the K^+π^…
Exploring correlations between the CP asymmetries of $B^0_d\toπ^0K_{\rm S}$ following from an isospin relation, we uncover new tensions with the Standard Model in data for neutral $B\toπK$ decays. Should this intriguing picture originate from New Physics, a modified electroweak penguin sector provides a key scenario. It includes models with extra $Z'$ bosons, which offer attractive ways to resolve anomalies in $B\to K^{(*)}\ell^+\ell^-$ measurements. We present a new strategy to reveal the underlying physics, apply it to current $B\toπK$ data, and discuss the excellent prospects for Belle II.
In recent years, several deviations from the Standard Model predictions in semileptonic decays of $B$-meson might suggest the existence of new physics which would break the lepton-flavour universality. In this work, we have explored the possibility of using muon sneutrinos and right-handed sbottoms to solve these $B$-physics anomalies simultaneously in $R$-parity violating minimal supersymmetric standard model. We find that the photonic penguin induced by exchanging sneutrino can provide sizable lepton flavour universal contribution due to the existence of logarithmic enhancement for the first…
The masses of the positive parity $[{\bf 70},0^+]$ and $[{\bf 70},2^+]$ non-strange baryons are calculated in large $N_c$ QCD by considering the most dominant operators in an $1/N_c$ expansion. The approach is based on the introduction of an excited core, obtained after the last particle (an excited quark) has been removed. Configuration mixing is neglected, for simplicity. Although being a sub-leading $1/N_c$ order, we find that the spin-spin interaction plays a dominant role in describing the data. The role of $N_c^ 0$ operators is also pointed out. We show how the contribution of the linear…
We discuss the electromagnetic-penguin-dominated radiative B decays $B \to X_s + γ, ~B^{\pm (0)} \to K^{*\pm (0)} + γ$, and $B_s \to ϕ+ γ$ in the context of the standard model (SM) and their Cabibbo-Kobayashi-Maskawa (CKM)-suppressed counterparts, $B \to X_d + γ$, $B^\pm \to ρ^\pm + γ, ~B^{0} \to (ρ^{0}, ω) + γ$, and $B_s \to K^{* 0} + γ$, using QCD sum rules for the exclusive decays. The importance of these decays in determining the parameters of the CKM matrix is emphasized. The semileptonic decays $B \to X_s \ell^+ \ell^-$ are also discussed in the context of the SM and their role in determ…
Search for New Physics through the Observables of Semileptonic $B_{c}^+\to D^{\ast+}\ell^{+}\ell^{-}$ Decay
National University of Sciences and Technology (NUST)（国立科学技术大学）；Lahore University of Management Sciences (LUMS)（拉合尔管理科学大学）；National Centre for Physics（国家物理中心）
We predict the amplitude of the $B\to K \ell^+\ell^-$ decay in the region of the dilepton invariant mass squared $0<q^2\leq m_{J/ψ}^2$, that is, at large hadronic recoil. The $B\to K$ form factors entering the factorizable part of the decay amplitude are obtained from QCD light-cone sum rules. The nonlocal effects, generated by the four-quark and penguin operators combined with the electromagnetic interaction, are calculated at $q^2<0$, far below the hadronic thresholds. For hard-gluon contributions we employ the QCD factorization approach. The soft-gluon nonfactorizable contributions are esti…
By employing the QCD factorization approach, we calculate the new physics contributions to the branching radios of the two-body charmless $ B \to PP$ decays in the framework of the minimal supergravity (mSUGRA) model. Within the considered parameter space, we find that (a) the supersymmetric (SUSY) corrections to the Wilson coefficients $C_k$ ($k=3-6$) are very small and can be neglected safely, but the leading order SUSY contributions to $C_{7γ}(M_W)$ and $C_{8g}(M_W)$ can be rather large and even change the sign of the corresponding coefficients in the standard model; (b) the possible SUSY c…
The decays $B_d^0\to J/ψK^0_{\text{S}}$and $B_s^0\to J/ψϕ$ play a key role for the determination of the $B^0_q$-$\bar B^0_q$ ($q=d,s$) mixing phases $ϕ_d$ and $ϕ_s$, respectively. The theoretical precision of the extraction of these quantities is limited by doubly Cabibbo-suppressed penguin topologies, which can be included through control channels by means of the $SU(3)$ flavour symmetry of strong interactions. Using the currently available data and a new simultaneous analysis, we discuss the state-of-the-art picture of these effects and include them in the extracted $ϕ_q$ values. We have a c…
We have studied the contribution of the high-scale SUSY to the K_L to pi^0 nu{bar nu} and K^+ to pi^+ nu{bar nu} processes correlating with the CP violating parameter epsilon_K. Taking account of the recent LHC results for the Higgs discovery and the SUSY searches, we consider the high-scale SUSY at the 10-50 TeV scale in the framework of the non-minimal squark (slepton) flavor mixing. The Z penguin mediated the chargino dominates the SUSY contribution for these decays. At the 10 TeV scale of the SUSY, the chargino contribution can enhance the branching ratio of K_L to pi^0 nu{bar nu} in eight…
