arXiv subjects

F. Falahati

Publications and source records attributed to F. Falahati.

10 recordsLinked to original sources

arXiv2015

Lepton polarization and CP-violating effects in $\overline{B}\rightarrow \overline{K}_{0}^{*}(1430) \ell^+\ell^-$ Decay in Standard and Two Higgs Doublet Model

In this paper we analyze the dilepton mass square $q^2$ dependency of single lepton polarization asymmetries and CP violation for $\overline{B}\rightarrow \overline{K}_0^{*}(1430) \ell^+\ell^-, \ell=μ,τ)$ in the 2HDM context. Also, we study the averages of these asymmetries in the domain $4 m_{\ell}^2<q^2< (m_B-m_{{K}_0^{*}})^2$. Our study manifests that the investigation of the above-mentioned asymmetries for $\overline{B}\rightarrow \overline{K}_0^*(1430) \ell^+\ell^-$ processes could provide useful information for probing new Higgs bosons in the future B-physics experiments.

hep-ph↗

arXiv2015

Polarized and Unpolarized Lepton Pair Forward-backward Asymmetries in $\overline{B}\rightarrow \overline{K}_{0}^{*}(1430) \ell^+\ell^-$ and $\overline{B}\rightarrow \overline{K} \ell^+\ell^-$ Decays in Two Higgs Doublet Model

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 of these asymmetries for $\overline{B}\rightarrow \overline{K}_0^*(1430) \ell^+\ell^-$ and $\overline{B}\rightarrow \overline{K} \ell^+\ell^-$ processes are very effective tools for establishing new physics in the future B-physics experiments.

hep-ph↗

arXiv2011

Exclusive $D_{s} \to (η,η^{\prime}) l ν$ decays in light cone QCD

Probing the $\bar ss$ content of the $η$ and $η'$ mesons and considering mixing between these states as well as gluonic contributions, the form factors responsible for semileptonic $D_s \to (η, η') l ν$ transitions are calculated via light cone QCD sum rules. Corresponding branching fractions and their ratio for different mixing angles are also obtained. Our results are in a good consistency with experimental data as well as predictions of other nonperturbative approaches.

hep-ph↗

arXiv2010

Rare Semileptonic $B_{s}$ Decays to $η$ and $η'$ mesons in QCD

We analyze the rare semileptonic $B_s \to (η, η') l^+ l^-$, $(l=e, μ, τ)$ and $B_s \to (η, η') ν\barν$ transitions probing the $\bar s s$ content of the $η$ and $η'$ mesons via three--point QCD sum rules. We calculate responsible form factors for these transitions in full theory. Using the obtained form factors, we also estimate the related branching fractions and longitudinal lepton polarization asymmetries. Our results are in a good consistency with the predictions of the other existing nonperturbative approaches.

hep-ph↗

arXiv2009

Analysis of the $B_q\to D_q(D_q^) P$ and $B_q\to D_q(D_q^) V$ decays within the factorization approach in QCD

Using the factorization approach and considering the contributions of the current-current, QCD penguin and electroweak penguin operators at the leading approximation, the decay amplitudes and decay widths of $B_q\to D_q(D_q^*) P$ and $B_q\to D_q(D_q^*) V$ transitions, where $q=u,d,s$ and P and V are pseudoscalar and vector mesons, are calculated in terms of the transition form factors of the $B_q\to D_{q}$ and $B_q\to D^{*}_{q}$. Having computed those form factors in three-point QCD sum rules, the branching fraction for these decays are also evaluated. A comparison of our results with the predictions of the perturbative QCD as well as the existing experimental data is presented.

hep-ph↗

arXiv2009

Investigation of the $D_{s1}$ structure via $B_c$ to $D_{s1} l^+l^-/ν\barν$ transitions in QCD

We investigate the structure of the $D_{s1}(2460,2536) (J^P=1^+)$ mesons via analyzing the semileptonic $B_{c}\to D_{s1}l^+l^-$, $l=τ, μ, e$ and $B_{c}\to D_{s1}ν\barν$ transitions in the framework of the three--point QCD sum rules. We consider the $D_{s1}$ meson in two ways, the pure $|c\bar{s}>$ state and then as a mixture of two $|^3P_1>$ and $|^1P_1>$ states. Such type rare transitions take place at loop level by electroweak penguin and weak box diagrams in the standard model via the flavor changing neutral current transition of $b \to s$. The relevant form factors are calculated taking into account the gluon condensate contributions. These form factors are numerically obtained for $|c\bar s>$ case and plotted in terms of the unknown mixing angle $θ_s$, when the $D_{s1}$ meson are considered as mixture of two $|^3P_1>$ and $|^1P_1>$ states. The obtained results for the form factors are used to evaluate the decay rates and branching ratios. Any future experimental measurement on these form factors as well as decay rates and branching fractions and their comparison with the obtained results in the present work can give considerable information about the structure of this meson and the mixing angle $θ_s$.

hep-ph↗

arXiv2008

Double-Lepton Polarization Asymmetries in $B_s \rar ϕ\ell^+ \ell^-$ Decay in the Fourth-Generation Standard Model

In this paper, we investigate the effects of the fourth generation of quarks on the double-lepton polarization asymmetries in the $B_s \rar ϕ\ell^+ \ell^-$ decay. It is shown that these asymmetries in $B_s \rar ϕ\ell^+ \ell^-$ decay compared with those of $B \rar K \ell^+ \ell^-$ decay are more sensitive to the fourth-generation parameters. We conclude that an efficient way to establish the existence of the fourth generation of quarks could be the study of these asymmetries in the $B_s \rar ϕ\ell^+ \ell^-$ decay.

hep-ph↗

arXiv2008

Analysis of the Rare $B_c \to D_{s,d}^{*} l^+ l^-$ Decays in QCD

The rare $B_c \to D_{s,d}^{*} l^+ l^-$ decays are investigated in the framework of the three point QCD sum rules approach. Considering the gluon condensate corrections to the correlation function, the form factors relevant to these transitions are calculated. The total decay width and branching ratio for these decays are also evaluated. The results for the branching ratios are in good agreement with the quark models.

hep-ph↗

arXiv2008

The Effects of Fourth Generation on the double Lepton Polarization in B \rar K \ell^+ \ell^- decay

This study investigates the influence of the fourth generation quarks on the double lepton polarizations in B \rar K \ell^+ \ell^- decay. Taking |V_{t's}V_{t'b}|\sim \{0.01-0.03\} with phase about 100^\circ, which is consistent with the b\to s\ell^+\ell^- rate and the B_s mixing parameter Delta m_{B_s}$, we obtain that the double lepton(muon and tau) polarizations are quite sensitive to the existence of fourth generation. It can serve as a good tool to search for new physics effects, precisely, to indirect search for the fourth generation quarks(t', b').

hep-ph↗

arXiv2007

Double Lepton Polarization Forward--Backward Asymmetries in B \rar K^\ast \ell^+ \ell^- Decay in the SM4

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 diagrams.

hep-ph↗