We analyze the $B\to K_2^*(\to Kπ)l^+l^-$ (with $l=e,μ,τ$) decay in the standard model and two new physics scenarios: vector-like quark model and family non-universal $Z'$ model. We derive its differential angular distributions, using the recently calculated form factors in the perturbative QCD approach. Branching ratios, polarizations, forward-backward asymmetries and transversity amplitudes are predicted, from which we find a promising prospective to observe this channel on the future experiment. We also update the constraints on effective Wilson coefficients and/or free parameters in these two new physics scenarios by making use of the experimental data of $B\to K^*l^+l^-$ and $b\to sl^+l^-$. Their impact on $B\to K_2^*l^+l^-$ is subsequently explored and in particular the zero-crossing point for the forward-backward asymmetry in these new physics scenarios can sizably deviate from the SM scenario. In addition we also generalize the analysis to a similar mode $B_s\to f_2'(1525)(\to K^+K^-) l^+l^-$.
The polarized lepton pair forward-backward asymmetries in (B -> rho l^+ l^-) decay using a general, model independent form of the effective Hamiltonian is studied. The general expression for nine double-polarization forward-backward asymmetries are calculated. The study of the forward-backward asymmetries of the doubly-polarized lepton pair proves to be very useful tool in looking for new physics beyond the standard model.
We study the polarized lepton pair forward-backward asymmetries in (B -> K^* l^+ l^-) decay using a general, model independent form of the effective Hamiltonian. We present the general expression for nine double-polarization forward-backward asymmetries. It is shown that, the study of the forward-backward asymmetries of the doubly-polarized lepton pair is a very useful tool for establishing new physics beyond the standard model.
Polarized forward-backward asymmetries in the (B_s -> l^+ l^- gamma) decay are calculated using the most general, model independent form of the effective Hamiltonian, including all possible forms of interactions. The dependencies of the asymmetries on new Wilson coefficients are investigated. The detectability of the asymmetries at LHC is discussed.
The measurement of the forward-backward asymmetries of heavy quarks provides one of the most precise determinations of $\sin^2θ_W$ in $Z$ decays. We discuss in detail the one--loop QCD radiative corrections to these asymmetries. Results are given for single heavy--quark jet asymmetries and asymmetries of the thrust axis, as well as for heavy--quark two--jet final states.}
We study the doubly-polarized lepton pair forward-backward asymmetries in (Lambda_b -> Lambda l^+ l^-) decay using a general, model independent form of the effective Hamiltonian. We present the general expression for nine double-polarization forward-backward asymmetries. It is observed that, the study of the forward-backward asymmetries of the doubly-polarized lepton pair is a very useful tool for establishing new physics beyond the standard model. Moreover, the correlation between forward-backward asymmetry and branching ratio is investigated. It is shown that there exist certain certain regi…
This study examines the influence of the fourth generation quarks on the double lepton polarizations forward--backward asymmetries in B \rar K^\ast \ell^+ \ell^- decay. We obtain that for both (muon, tau) channels the magnitude and the sign of the differential forward--backward asymmetries and the magnitude of the average forward--backward asymmetries are quite sensitive to the 4th generation quarks mass and mixing parameters. It can serve as a good tool to search for new physics effects, precisely, to search for the fourth generation quarks(t', b') via its indirect manifestations in the loop …
We study the double-lepton polarization asymmetries and single and double-lepton polarization forward backward asymmetries of the rare b \to s \ell^+ \ell^- mode within the Standard Model and in the Appelquist-Cheng-Dobrescu model, which is a new physics scenario with a single universal extra dimension. In particular, we examine the sensitivity of the observables to the radius R of the compactified extra-dimension, which is the new parameter in this new physics model.
Double polarized forward-backward asymmetries in $B\rightarrow K_{1}(1270,1400)\ell^{+}\ell^{-}$ with $\ell=μ, τ$ decays are studied, using most general non-standard local four-fermi interactions, where the mass eigenstates $K_{1}(1270)$ and $K_{1}(1400)$ are the mixture of $^{1}{P}_{1}$ and $^{3}{P}_{1}$ states with the mixing angle $θ_{K}$. We have calculated the expressions of nine doubly polarized forward-backward asymmetries and it is presented that the polarized lepton pair forward-backward asymmetries are greatly influenced by the new physics. Therefore, these asymmetries are interestin…
We study the forward-backward and the CP-violating asymmetries (both time-independent and time-dependent) in rare semileptonic and radiative leptonic B_{d,s}-decays and investigate the sensitivity of these asymmetries to the extensions of the Standard model.
We study the forward-backward and the CP-violating asymmetries (both time-independent and time-dependent) in rare semileptonic $B_d\toρ^0 l^+l^-$, $B_s\toϕl^+l^-$, and radiative leptonic $B_{d,s}\to γl^+l^-$ decays and investigate the sensitivity of these asymmetries to the extensions of the Standard model.
In a recent paper we presented a calculation of NNLL virtual corrections to the forward-backward asymmetries in $b\to X_s\ell^+\ell^-$ decay. That result does not include bremsstrahlung corrections which are free from infrared and collinear singularities. In the present paper we include the remaining ${\cal O}(α_s)$ bremsstrahlung corrections to the forward-backward asymmetries in $b\to X_s\ell^+\ell^-$ decay. The numerical effect of the calculated contributions is found to be below 1%.
We examine the O(alpha_s) forward-backward asymmetries for the production process e+ e- --> gamma,Z --> q qbar (g), tagging the outgoing heavy-quark jet at center-of-momentum energies off the Z-peak. The complicated analytic results are reduced to simple polynomial forms that provide excellent approximations. For charm and bottom quark, a full dynamical cancellation gives O(alpha_s) zeros in the forward-backward asymmetry close to the Z-peak. We conclude with a detailed numerical analysis of our results.
It has now become possible to observe appreciable numbers of hadronically produced lepton pairs in mass ranges where the contributions of the photon and $Z^0$ are comparable. Consequently, in the reaction $p \bar p \to \ell^- \ell^+ + \ldots$, substantial forward-backward asymmetries can be seen. These asymmetries provide a test of the electroweak theory in a new regime of energies, and can serve as diagnostics for any new neutral vector bosons coupling both to quarks and to charged lepton pairs.
We provide a qualitative and quantitative unified picture of the charge asymmetry in top quark pair production at hadron colliders in the SM and summarise the most recent experimental measurements.
We study the spin polarizations of both tau leptons in the decay b -> s tau+ tau-. In addition to the polarization asymmetries involving a single tau, we construct asymmetries for the case where both polarizations are simultaneously measured. We also study forward-backward asymmetries with polarized tau's. We find that a large number of asymmetries are predicted to be large, >~ 10%. This permits the measurement of all Wilson coefficients and the b-quark mass, thus allowing the standard model (SM) to be exhaustively tested. Furthermore, there are many unique signals for the presence of new phys…
Using the Bethe-Salpeter equation (BSE) we investigate the forward-backward asymmetries $( A_{FB}) $ in $Λ_b \rightarrow Λl^+ l^-(l=e,μ,τ)$ in the quark-diquark model. This approach provides precise form factors that are different from those of QCD sum rules. We calculate the rare decay form factors for $Λ_b \rightarrow Λl^+ l^-$ and investigate the (integrated) forward-backward asymmetries in these decay channels. We find that the integrated $A^l_{FB}$, $\bar{A}^l_{FB}(Λ_b \rightarrow Λe^+ e^-) \simeq -0.1371 $, $\bar{A}^l_{FB}(Λ_b \rightarrow Λμ^+ μ^- ) \simeq -0.1376 $, $\bar{A}^l_{FB}(Λ_b …
Precision determinations of Standard Model (SM) Electro-Weak (EW) parameters at the Large Hadron Collider (LHC) are dominated by uncertainties due to Parton Distribution Functions (PDFs). Reweighting and profiling techniques are routinely employed to treat this. We explore approaches based on combining measurements of charged current and neutral current Drell-Yan (DY) asymmetries to improve PDF uncertainties. We present the results of a numerical analysis performed with the open-source platform xFitter. PDF uncertainties are examined for lepton-charge and forward-backward asymmetries in region…
We investigate the possibility of scalar interaction affecting the forward backward asymmetry in the decay mode $B\to K μ^+ μ^-$. Using the scalar contribution and advocating Cheng-Sher type ansatz we obtain sizable forward backward asymmetry. Furthermore, we study the effect of the scalar interaction in $K^+ \to π^+ μ^+ μ^-$. It is pointed out that non-zero forward backward asymmetry in $B\to K l^+ l^-$, if found in future B-factories, may indicate the new physics in the scalar sector.
We present NNLL results for the double differential decay width dGamma(b -> X_s l+ l-)/(dsh dcos(theta)), where theta is the angle between the momenta of the b-quark and the l+, measured in the rest-frame of the lepton pair. From these results we also derive NNLL results for the lepton forward-backward asymmetries. Genuinely new calculations for the combined virtual- and gluon bremsstrahlung corrections associated with the operators O_7, O_9 and O_10 are necessary. We find that the NNLL corrections drastically reduce the renormalization scale dependence of the forward-backward asymmetries. In …
We discuss an improved theoretical description of the semi-inclusive B meson decays $B\to K(K^*)X$. The decay distributions are calculated. Their branching ratios are found to be appreciable. The CP asymmetries in the neutral B modes $\bar{B^0}\to K^-(K^{*-})X$ are sizable. An observation of direct CP violation and a measurement of $γ$ may come from these neutral B modes.
We address the impact of future measurements of charged and neutral current Drell-Yan (DY) asymmetries and their combination on Parton Distribution Functions (PDFs) uncertainties. We quantify the reduction of PDF uncertainties using the QCD tool xFitter. We examine the effects of such reduced PDF errors on both Standard Model (SM) and Beyond SM (BSM) observables.
We study the impact of future measurements of lepton-charge and forward-backward asymmetries in Drell-Yan processes in regions of transverse and invariant masses near the Standard Model gauge bosons peaks to improve the Parton Distribution Functions uncertainties. We study the implications on $W^{'}$ and $Z^{'}$ searches following the reduction of these uncertainties. We find that the sensitivity to the Beyond the Standard Model states is greatly increased with respect to the case of base Parton Distribution Functions sets, thereby enabling one to set more stringent limits on (or indeed discov…
This paper presents the first calculations of the parity-violating polarization asymmetry and forward-backward asymmetry of the $e^- e^+ \rightarrow μ^+ μ^- (γ)$ process at a center-of-mass energy of 10.58 GeV with up to one-loop electroweak radiative corrections. The calculations are relevant for future precision electroweak measurements at the Belle~II experiment, which is now collecting data at the SuperKEKB $e^- e^+$ collider with a center-of-mass energy at the mass of the $Υ(4S)$ resonance. In this paper we take under full control the bremsstrahlung process at the conditions of Belle II/S…
We investigate the forward-backward asymmetries in the pair production of fourth family fermions through the new Z' interactions in the e+e- collisions. The Z' boson having family universal couplings can contribute to the pair production of fourth family fermions via the s-channel exchange. The linear colliders will provide a clean environment for the physics of Z' boson to measure its couplings precisely. The effects of the Z' boson to the asymmetries are shown to be important in some parameter regions for different Z' models. Among these parameters, the invariant mass distribution m_FFbar wi…
We study the radiative dileptonic $B \rar γl^+ l^- $ transition in the presence of a universal extra dimension in the Applequist-Cheng-Dobrescu model. In particular, using the corresponding form factors calculated via light cone QCD sum rules, we analyze the branching ratio and double lepton polarization asymmetries related to this channel and compare the results with the predictions of the standard model. We show how the results deviate from predictions of the standard model at lower values of the compactification factor ($1/R $) of extra dimension.
Using the covariant constituent quark model previously developed by us we calculate the differential rate and the forward-backward asymmetries on the lepton and hadron side for the rare baryon decays Lambda_b -> Lambda l+ l- (l=e, mu, tau) and Lambda_b -> Lambda gamma. We use helicity methods to write down a three-fold joint angular decay distribution for the cascade decay Lambda_b -> Lambda (-> p pi-) + J_eff (-> l+ l-). Through appropriate angular integrations we obtain expressions for the rates, the lepton-side forward-backward (FB) asymmetry and the polarization of the daughter baryon Lamb…
The relatively clean theoretical probes of the Standard Model (SM), and the various theories beyond the SM, provided by radiative, semi-leptonic and (purely) leptonic decays of B-mesons have become increasingly important. Due to the large number of possible distributions in the semi-leptonic decays based on the quark level transition $b \to s \ell^+ \ell^-$ (not just the branching ratio), these transitions have become very useful. A study of the Forward-Backward asymmetries for the inclusive decay ($B \to X_s \ell^+ \ell^-$) is carried out in this paper. This study shall be performed in the SM…
We analyze the supersymmetric contributions to the direct and mixing CP asymmetries and also to the branching ratios of the B --> K πdecays in a model independent way. We consider both gluino and chargino exchanges and emphasize that a large gluino contribution is essential for saturating the direct and mixing CP asymmetries. We also find that combined contributions from the penguin diagrams with chargino and gluino in the loop could lead to a possible solution for the branching ratios puzzle and account for the results of R_c and R_n within b --> s γconstraints. When all relevant constraints …
Theoretically motivated smallness of the penguin amplitude in $B \to ππ$ decays allowes to calculate the value of the unitarity triangle angle $α(ϕ_2)$ with good accuracy. The relatively large branching ratio of the decay into $π^0 π^0$ is explained by the large value of FSI phase difference between $ΔI = 1/2$ and $ΔI = 3/2$ tree amplitudes.
In this paper we shall focus on the effects of concrete models such as SM and Model III of 2HDM on the polarized and unpolarized forward-backward asymmetries of $\overline{B}\rightarrow \overline{K}_0^{*}(1430) \ell^+\ell^-$ and $\overline{B}\rightarrow \overline{K} \ell^+\ell^-$ decays. The obtained results of these decay modes are compared to each other. Also, we obtain the minimum required number of events for detecting each asymmetry and compare them with the number of produced $B\bar{B}$ pairs at the LHC or supposed to be produced at the Super-LHC. At the end, we conclude that the study o…
We consider the next-to-leading order corrections, O(alpha_s), to forward-backward charge asymmetries for lepton-pair production in association with a large transverse momentum jet at large hadron colliders. We find that the leading order results are essentially confirmed. Although experimentally challenging and in practice with large backgrounds, these observables could provide a new determination of the weak mixing angle sin2 theta^lept_eff (M_Z^2) with a statistical precision for each lepton flavour of ~10^(-3) (7 x 10^{-3}) at LHC (Tevatron), and if b jets are identified, of the b quark Z …
We investigate the $B \rar K_{0}^{*}(1430) l^+ l^- $ transition in the Applequist-Cheng-Dobrescu model in the presence of a universal extra dimension. In particular, we calculate double lepton polarization asymmetries and branching ratio related to this channel and compare the obtained results with the predictions of the standard model. Our analysis of the considered observables in terms of radius $R$ of the compactified extra-dimension as the new parameter of the model show a considerable discrepancy between the predictions of two models in low $\frac{1}{R}$ values.
Leptonic and semi-leptonic rare decays of B-mesons are very clean (both theoretically and experimentally) signatures of any new physics beyond the Standard Model (SM). More specifically the decay \btokll has been theoretically observed to be very sensitive to new physics as the Forward Backward (FB) asymmetry in this decay mode vanishes in the SM. Supersymmetry, however, predicts a non-vanishing value of this asymmetry. In this work we will study the polarized lepton pair FB asymmetry, i.e. the FB asymmetry of the lepton when one (or both) final state lepton(s) are polarized. We will study the…
The exclusive semileptonic $B\to K_{1}(1270) \ell^{+}\ell^{-}$ ($\ell=μ, τ$) decays are analyzed in variants of two Higgs double models (THDMs). The mass eigenstates $K_{1}(1270)$ and $K_{1}(1400)$ are the mixture of two axial-vector SU(3) $^{1}{P}_{1}$ and $^{3}{P}_{1}$ states with the mixing angle $θ_{K}$. Making use of the form factors calculated in the Light Cone QCD approach and by taking the mixing angle $θ_{K}=-34^{\circ}$, the impact of the parameters of the THDMs on different asymmetries in above mentioned semileptonic $B$ meson decays are studied. In this context the forward-backward…
We compute, for top quark pair production at the Tevatron and the Large Hadron Collider, the collider-independent forward-backward asymmetries defined in [1] in the standard model at next-to-leading order in QCD, including also electromagnetic and weak corrections.
We investigate the exclusive nonleptonic decays $B\rightarrow χ_{c1}K(π)$ in the conventional perturbative QCD (PQCD) formalism. The predictions of branching ratios and $CP$ asymmetries are given in detail. We compare our results with available experimental data as well as predictions of other theoretical studies existing in the literature. It seems that the branching ratios of $B\rightarrow χ_{c1} K$ are more consistent with data than the earlier analyses. For the Cabibbo-suppressed $B_s$ decay, the branching ratio can reach the order of $10^{-5}$, which would be straight forward for experime…
We introduce the forward-backward asymmetries A_u, A_d corresponding to u ubar, d dbar -> t tbar production, respectively, at hadron colliders. These are collider- and center-of-mass-independent observables, directly related to the forward-backward and charge asymmetries measured at the Tevatron and the LHC, respectively. We discuss how to extract these asymmetries from data. Because these asymmetries are collider-independent, their measurement at these two colliders could elucidate the nature of the anomalous forward-backward asymmetry measured at the Tevatron. Our framework also shows in a m…
In this work, within the QCD factorization approach, we investigate the branching fractions and CP asymmetries of decays $B \to K_0^*(1430)ρ$ and $B \to K_0^*(1430)ϕ$ under two different scenarios both in the standard model and the family nonuniversal $Z^\prime$ model. We find that the annihilation terms play crucial roles in these decays and lead to the main uncertainties. For decays $B^- \to \bar K_0^{*-} (1430)ρ^0 (ω)$, the new $Z^\prime$ boson could change branching fractions remarkably. However, for other decays, its contribution might be clouded by large uncertainties from annihilations.…
We consider two body decays of B meson into a light vector (V) and a pseudoscalar (P) meson. The constraint obtained from the $B\to P P$ modes on the parameter space of the input parameters is imposed also on $B\to V P$ modes. In particular we constrain $ξ\equiv (1/N_c)$ for those modes from recently measured $B\to ωK, ϕK$ and are able to get a satisfactory pictures for all modes where data exists. Modes that should be seen shortly and those with possibly large CP asymmetries are identified.
Predictions are made for the forward-backward and charge asymmetries in bottom-quark pair production at hadron colliders. Tree-level exchanges of electroweak (EW) gauge bosons dominate the Standard Model (SM) contribution to the asymmetry near the $Z$-pole. The mixed EW-QCD corrections are computed in an approximate way, and are found to be small in magnitude. These SM predictions are consistent with experimental results from CDF, D0, and LHCb. In particular, CDF and LHCb find that the asymmetry in the invariant mass bin containing the $Z$-pole is larger than in the adjacent bins, as predicted…
We study long-distance effects in rare exclusive semileptonic decays B -> K_{1}ell ^{+}ell ^{-}, K_{1} is the axial vector meson.The form factors, describing the meson transition amplitudes of the effective Hamiltonian, are calculated using Ward identites which are then used to calculate branching ratio and forward-backward asymmetry in these decay modes. The zero of forward-backward asymmetry is of special interest and provide us the precission test of Standard model.
We study the two-body hadronic $D\to PV$ decays, where $P$ ($V$) denotes a pseudoscalar (vector) meson, in the factorization-assisted topological-amplitude approach proposed in our previous work. This approach is based on the factorization of short-distance and long-distance dynamics into Wilson coefficients and hadronic matrix elements of four-fermion operators, respectively, with the latter being parametrized in terms of several nonperturbative quantities. We further take into account the $ρ$-$ω$ mixing effect, which improves the global fit to the branching ratios involving the $ρ^0$ and $ω$…
Within the paradigm of warped extra dimensions, third generation quarks are expected to be the most sensitive to effects beyond the Standard Model. The anomalies observed at the LEP and Tevatron colliders in the forward-backward asymmetries of the bottom (A_FB^b) and top (A_FB^t) quarks can thus be seen as early signatures of warped extra-dimensional scenarios. We propose a realization of such a scenario, with a gauge custodial symmetry in the bulk, which allows to address simultaneously the A_FB^b anomaly and the discrepancies observed recently on A_FB^t at high top quark rapidities and ttbar…
We calculate the branching ratios and CP violating asymmetries of the four $B \to K \etap$ decays in the perturbative QCD (pQCD) factorization approach. Besides the full leading order contributions, the partial next-to-leading order (NLO) contributions from the QCD vertex corrections, the quark loops, and the chromo-magnetic penguins are also taken into account. The NLO pQCD predictions for the CP-averaged branching ratios are $Br(B^+ \to K^+ η) \approx 3.2 \times 10^{-6}$, $Br(B^\pm \to K^\pm \etar) \approx 51.0 \times 10^{-6}$, $Br(B^0 \to K^0 η) \approx 2.1 \times 10^{-6}$, and $Br(B^0 \to …
Longitudinally polarized, unpolarized and forward-backward mass differential cross sections for Drell-Yan lepton-pair production by arbitrary vector bosons are calculated in next-to-leading order (NLO) QCD. Analytical results are presented in a form valid for all consistent $n$-dimensional regularization schemes, with the mass factorization scheme kept general. NLO predictions for all Drell-Yan type processes ($W^\pm$, $Z$ and $γ^*$) at BNL's relativistic heavy ion collider (RHIC) are made using polarized parton distributions which fit the recent deep-inelastic scattering data. These are exami…
We compute the branching ratio and forward-backward asymmetry ($A_{FB}$) distribution for the rare dileptonic decay $B \to K^* μ^+ μ^-$ for the full range of $q^2$, the dimuon mass squared, region. For the required form factors, we use nonperturbative inputs as predicted by the anti-de Sitter (AdS)/QCD correspondence. When using the Breit-Wigner model with momentum-dependent decay constants to account for the $ψ$ and $ψ^\prime$ resonance effects in the nonresonance region of the spectrum, we find our predictions to be in better agreement with the experimental data for the branching ratio.
We study the dilepton forward-backward and the longitudinal, normal and transverse lepton polarization asymmetries in the heavy baryon decays of $Λ_b\toΛl^+l^-$. We show that the asymmetries have a less dependence on the non-perturbative QCD effects. In the standard model, we find that the integrated forward-backward asymmetries (FBAs) and three components of the polarizations in the QCD sum rule approach (pole model) are $-0.13\ (-0.12)$ and $(58.3,-9.4,-0.07)%$ ($(58.3,-12.6,-0.07)%$) for $Λ_b\toΛμ^+μ^-$ and $-0.04 (-0.03)$ and $(10.9,-10.0,-0.39)%$ ($(10.9,-0.2,-0.34)%$) for $Λ_b\toΛτ^+τ^-$…
The forward-backward asymmetry A_{FB}^t in top quark production at the Tevatron has been seen to be anomalously large both by CDF and D0. Parton-level asymmetries as large as 50%, with a large error bar, have been extracted from the data. It is important to measure other quark asymmetries if possible, as these would help clarify the source of any new physics behind A_{FB}^t. In this note it is argued that asymmetries in b\bar b and c\bar c should be accessible to the Tevatron experiments, using the full data sets. A crude study suggests that muon asymmetries in high-p_T dijet events, with suit…
The mass eigen states $K_1(1270)$ and $K_1(1400)$ are mixture of the strange members of two axial-vector SU(3) octet, $^3P_1(K_1^A)$ and $^1P_1(K_1^B)$. Taking into account this mixture, the forward-backward asymmetry and branching ratio of $B \rar K_1(1270,1400) \ell^+ \ell^-$ transitions are studied in the framework of different supersymmetric models. It is found that the results have considerable deviation from the standard model predictions. Any measurement of these physical observables and their comparison with the results obtained in this paper can give useful information about the natur…
Nonleptonic two body B decays including radially excited $π(1300)$ or $ρ(1450)$ mesons in the final state are studied using the framework of generalized naive factorization approach. Branching ratios and CP asymmetries of $B\to Pπ(1300)$, $B\to Vπ(1300)$, $B\to Pρ(1450)$ and $B\to Vρ(1450)$ decays are calculated, where P and V stand for pseudoscalar and vector charmless mesons. Form factors for $B\to π(1300)$ and $B\to ρ(1450)$ transitions are estimated in the improved version of the Isgur-Scora-Grinstein-Wise quark model. In some processes, CP asymmetries of more than 10% and branching ratios…
We present a theoretical reappraisal of the branching ratios and CP asymmetries for the decays $ B \to X_q \ell^+ \ell^-$, with $q=d,s$, taking into account current theoretical uncertainties in the description of the inclusive decay amplitudes from the long-distance contributions, an improved treatment of the renormalization scale dependence, and other parametric dependencies. Concentrating on the partial branching ratios $Δ{\cal B}(B \to X_q \ell^+ \ell^-)$, integrated over the invariant dilepton mass region $1 {GeV}^2 \leq s \leq 6 {GeV}^2$, we calculate theoretical precision on the charge-c…
The large cross sections for gauge boson production at the Fermilab Tevatron and the CERN Large Hadron Collider (LHC) might give a chance to determine the electroweak parameters with high precision. We calculated two different forward-backward charge asymmetries (A^CS_FB and A^j_FB) of lepton pairs in events with a large transverse momentum jet p p (pbar) -> Z, gamma* + j -> e- e+ j at next-to-leading order (NLO), O(alpha_s) corrections, making use of the Monte Carlo programs MCFM and ALPGEN. These observables could provide a new determination of the weak mixing angle sin^2 theta^lept_eff (M_Z…
We have calculated inclusive direct CP-asymmetries for charmless B^{+/-} -decays. After summing large logarithms to all orders the CP-asymmetries in Delta S=0 and Delta S=1 decays are found as a_{CP} (Delta S=0) = (2.0 +1.2/-1.0)% and a_{CP} (Delta S=1) = ( -1.0 +/- 0.5)%. These results are much larger than previous estimates based on a work without summation of large logarithms. We further show that the dominant contribution to a_{CP} (ΔS=0 ) is proportional to (sin gamma) times |V_{cb}/V_{ub}|. The constraints on the apex (rho-bar,eta-bar) of the unitarity triangle obtained from these two CP…
We analyzed the nonleptonic decays $B/B_s\to ψ(2S) V $ with $V=(ρ, ω, K^{*}, ϕ)$ by employing the perturbative QCD (PQCD) factorization approach. Here the branching ratios, the $CP$ asymmetries and the complete set of polarization observables are investigated systematically. Besides the traditional contributions from the factorizable and nonfactorizable diagrams at the leading order, the next-to-leading order (NLO) vertex corrections could also provide considerable contributions. The PQCD predictions for the branching ratios of the $B_{(s)}\to ψ(2S)K^{*}, ψ(2S) ϕ$ decays are consistent with th…
Motivated by the recent LHCb collaboration measurements of charmless three-body decays of $\bar B_s^0$ meson, we calculate the branching fractions of $\bar B_s ^0 \to K^0 π^+π^-$, $\bar B_s ^0 \to K^0 K^+K^-$, $\bar B_s ^0 \to K^0 π^+K^-$ and $\bar B_s ^0 \to \bar K^0 K^+π^-$ decay modes using the factorization approach. Both the resonant and nonresonant contributions are studied in detail. For the decays $\bar B_s ^0 \to K^0 π^+π^-$ and $\bar B_s ^0 \to K^0 K^+K^-$, our results agree well with experimental data, and the former is dominated by the $K^*$, while the latter one is dominated by th…
Using the $B\to K_1$ form factors evaluated in the perturbative QCD approach, we study semileptonic $B\to K_1(1270)l^+l^-$ and $B\to K_1(1400)l^+l^-$ decays, where $K_1(1270)$ and $K_1(1400)$ are mixtures of $K_{1A}$ and $K_{1B}$ which are $^3P_1$ and $^1P_1$ states, respectively. Using the technique of helicity amplitudes, we express the decay amplitudes in terms of several independent and Lorentz invariant pieces. We study the dilepton invariant mass distributions, branching ratios, polarizations and forward-backward asymmetries of $ B\to K_1l^+l^-$ decays. The ambiguity in the sign of the m…
Based on the low-energy effective Hamiltonian with the generalized factorization, we calculate the new physics contributions to branching ratios and CP-violating asymmetries of the charmless hadronic decays $B_s \to h_1 h_2$ in the standard model and the general two-Higgs doublet models (models I, II, and III). Within the considered paramter space, we find the following. (a) In models I and II, the new physics corrections are always small in size and will be masked by other larger known theoretical uncertainties. (b) In model III, the new physics corrections to the branching ratios of those QC…
Recently, CMS and ATLAS collaborations at LHC announced a Higgs like particle with mass near $125$GeV. Regarding this, to explore its intrinsic properties, different observables are needed to be measured precisely at the LHC for various decay channels of the Higgs. In this context, we calculate the final state lepton polarization asymmetries, namely, single lepton polarization asymmetries ($P_i$) and double lepton polarization asymmetries ($P_{ij}$) in the SM for radiative semileptonic Higgs decay $H\toγτ^+τ^-$. In the phenomenological analysis of these lepton polarization asymmetries both tre…
