The implications of the fourth generation quarks in the B-->K_{1}(1270,1400)l^{+}l^{-} with l=mu,... more The implications of the fourth generation quarks in the B-->K_{1}(1270,1400)l^{+}l^{-} with l=mu, tau decays are studied, 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 \theta_{K}. In this context, we have studied various observables like branching ratio (BR), forward backward asymmetry (A_{FB}) and longitudinal and transverse helicity fractions (f_{L,T}) of K_{1} meson in B-->K_{1}l^{+}l^{-} decays. To study these observables, we have used the Light Cone QCD sum rules form factors and set the mixing angle \theta_{K}=-34^{o}. It is noticed that the BR is suppressed for K_{1}(1400) as a final state meson compared to that of K_{1}(1270). Same is the case when the final state leptons are tauons rather than muons. In both the situations all the above mentioned observables are quite sensitive to the fourth generation effects. Hence the measurements of these observables at LHC, for the above mentioned processes can serve as a good tool to investigate the indirect searches for the existence of fourth generation quarks.
The implication of the fourth-generation quarks in the B -> K^*l^+l^- (l=mu,tau) decays, when K^*... more The implication of the fourth-generation quarks in the B -> K^*l^+l^- (l=mu,tau) decays, when K^* meson is longitudinally or transversely polarized, is presented. In this context, the dependence of the branching ratio with polarized K^* and the helicity fractions (f_{L,T}) of K^* meson are studied. It is observed that the polarized branching ratios as well as helicity fractions are sensitive to the NP parameters, especially when the final state leptons are tauons. Hence the measurements of these observables at LHC can serve as a good tool to investigate the indirect searches of new physics beyond the Standard Model.
A comparative study of the exclusive rare $B_{c}\rightarrow D_{s}^{\ast}\ell^{+}\ell^{-}$ ($\ell=... more A comparative study of the exclusive rare $B_{c}\rightarrow D_{s}^{\ast}\ell^{+}\ell^{-}$ ($\ell=\mu, \tau$) decays has been made in the minimal supersymmetric models (MSSM) and the SUSY SO(10) GUT models. In this context, various physical observables such as branching ratios $(\mathcal{BR})$, forward-backward asymmetries $(\mathcal{A}_{FB})$, lepton polarization asymmetries $(P_{L,N,T})$ and helicity fractions ($f_{L,T}$) of $D_{s}^{\ast}$ meson by using the the QCD sum rules form factors have been investigated. It is found that the SUSY effects are characteristically prominent to that of the SM values for these observables. For instance, in SUSY I and SUSY II, the forward-backward asymmetry does not cross zero which is mainly due to the same sign of the $C_{7}^{eff}$ and $C_{9}^{eff}$ Wilson coefficients. Similarly in SUSY SO(10) GUT models due to the complex nature of the new Wilson coefficients -- corresponding to the new operators arising due to the contribution of neutral Higgs bosons (NHBs) -- the above mentioned observables are sizably affected. Therefore the analysis of said observables in charmed semileptonic $B$ meson decays can put some stringent constraints on the parameter space of SUSY variants and can serve as a windowpane to look beyond the SM.
The weak decays of B_{c} --> D_{s}^{*}l^{+}l^{-} (l=mu,tau) are investigated in the Standard Mode... more The weak decays of B_{c} --> D_{s}^{*}l^{+}l^{-} (l=mu,tau) are investigated in the Standard Model with fourth generation (SM4). Taking fourth generation quark mass m_{t'} of about 300 to 600 GeV with the CKM matrix elements V_{t'b}^{*}V_{t's} in the range (0.03-1.2)*10^{-2} and using the new CP odd phase (phi_{sb}) to be 90^{o} the analysis of decay rates, forward-backward asymmetries, lepton polarization asymmetries and the helicity fractions of D_{s}^{*} meson in B_{c} --> D_{s}^{*}l^{+}l^{-} (l=mu,tau) is made. It is shown that the values of these physical observables are greatly influenced by the effects of extra sequential quark generation in the SM. It is found that the zero position of the forward-backward asymmetry in B_{c} --> D_{s}^{*} mu^{+} mu^{-} deviates significantly from that of the SM value while the effects in the decay rate, helicity fractions of D_s^{*} meson and the lepton polarization asymmetries are also quite promising. In B_{c} --> D_{s}^{*} tau^{+} tau^{-} decay, the SM4 the NP effects are somewhat mild in the decay rate and forward-backward asymmetry but they have shown them up in the longitudinal and transverse lepton polarization and also in the helicity fractions of the D_{s}^{*} meson which differ distinctively from the SM values. Thus the study of these physical observables will provide us useful information to probe new physics and helps us to search for the fourth generation of quarks (t',b') in an indirect way.
The implications of the fourth generation quarks in the B-->K_{1}(1270,1400)l^{+}l^{-} with l=mu,... more The implications of the fourth generation quarks in the B-->K_{1}(1270,1400)l^{+}l^{-} with l=mu, tau decays are studied, 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 \theta_{K}. In this context, we have studied various observables like branching ratio (BR), forward backward asymmetry (A_{FB}) and longitudinal and transverse helicity fractions (f_{L,T}) of K_{1} meson in B-->K_{1}l^{+}l^{-} decays. To study these observables, we have used the Light Cone QCD sum rules form factors and set the mixing angle \theta_{K}=-34^{o}. It is noticed that the BR is suppressed for K_{1}(1400) as a final state meson compared to that of K_{1}(1270). Same is the case when the final state leptons are tauons rather than muons. In both the situations all the above mentioned observables are quite sensitive to the fourth generation effects. Hence the measurements of these observables at LHC, for the above mentioned processes can serve as a good tool to investigate the indirect searches for the existence of fourth generation quarks.
The implication of the fourth-generation quarks in the B -> K^*l^+l^- (l=mu,tau) decays, when K^*... more The implication of the fourth-generation quarks in the B -> K^*l^+l^- (l=mu,tau) decays, when K^* meson is longitudinally or transversely polarized, is presented. In this context, the dependence of the branching ratio with polarized K^* and the helicity fractions (f_{L,T}) of K^* meson are studied. It is observed that the polarized branching ratios as well as helicity fractions are sensitive to the NP parameters, especially when the final state leptons are tauons. Hence the measurements of these observables at LHC can serve as a good tool to investigate the indirect searches of new physics beyond the Standard Model.
A comparative study of the exclusive rare $B_{c}\rightarrow D_{s}^{\ast}\ell^{+}\ell^{-}$ ($\ell=... more A comparative study of the exclusive rare $B_{c}\rightarrow D_{s}^{\ast}\ell^{+}\ell^{-}$ ($\ell=\mu, \tau$) decays has been made in the minimal supersymmetric models (MSSM) and the SUSY SO(10) GUT models. In this context, various physical observables such as branching ratios $(\mathcal{BR})$, forward-backward asymmetries $(\mathcal{A}_{FB})$, lepton polarization asymmetries $(P_{L,N,T})$ and helicity fractions ($f_{L,T}$) of $D_{s}^{\ast}$ meson by using the the QCD sum rules form factors have been investigated. It is found that the SUSY effects are characteristically prominent to that of the SM values for these observables. For instance, in SUSY I and SUSY II, the forward-backward asymmetry does not cross zero which is mainly due to the same sign of the $C_{7}^{eff}$ and $C_{9}^{eff}$ Wilson coefficients. Similarly in SUSY SO(10) GUT models due to the complex nature of the new Wilson coefficients -- corresponding to the new operators arising due to the contribution of neutral Higgs bosons (NHBs) -- the above mentioned observables are sizably affected. Therefore the analysis of said observables in charmed semileptonic $B$ meson decays can put some stringent constraints on the parameter space of SUSY variants and can serve as a windowpane to look beyond the SM.
The weak decays of B_{c} --> D_{s}^{*}l^{+}l^{-} (l=mu,tau) are investigated in the Standard Mode... more The weak decays of B_{c} --> D_{s}^{*}l^{+}l^{-} (l=mu,tau) are investigated in the Standard Model with fourth generation (SM4). Taking fourth generation quark mass m_{t'} of about 300 to 600 GeV with the CKM matrix elements V_{t'b}^{*}V_{t's} in the range (0.03-1.2)*10^{-2} and using the new CP odd phase (phi_{sb}) to be 90^{o} the analysis of decay rates, forward-backward asymmetries, lepton polarization asymmetries and the helicity fractions of D_{s}^{*} meson in B_{c} --> D_{s}^{*}l^{+}l^{-} (l=mu,tau) is made. It is shown that the values of these physical observables are greatly influenced by the effects of extra sequential quark generation in the SM. It is found that the zero position of the forward-backward asymmetry in B_{c} --> D_{s}^{*} mu^{+} mu^{-} deviates significantly from that of the SM value while the effects in the decay rate, helicity fractions of D_s^{*} meson and the lepton polarization asymmetries are also quite promising. In B_{c} --> D_{s}^{*} tau^{+} tau^{-} decay, the SM4 the NP effects are somewhat mild in the decay rate and forward-backward asymmetry but they have shown them up in the longitudinal and transverse lepton polarization and also in the helicity fractions of the D_{s}^{*} meson which differ distinctively from the SM values. Thus the study of these physical observables will provide us useful information to probe new physics and helps us to search for the fourth generation of quarks (t',b') in an indirect way.
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Papers by aqeel ahmed