Rukmani Mohanta

The fourth family: A simple explanation for the observed pattern of anomalies in B–CP asymmetries

We show that a fourth family of quarks with mt′mt′ in the range of (400–600) GeV provides a rather simple explanation for the several indications of new physics that have been observed involving CP asymmetries of the b -quark. The built-in hierarchy of the 4×44×4 mixing matrix is such that the t′t′ readily provides a needed perturbation (≈15%≈15%) to sin2βsin2β as measured in B→ψKsB→ψKs and simultaneously is the dominant source of CP asymmetry in Bs→ψϕBs→ψϕ. The correlation between CP asymmetries in Bs→ψϕBs→ψϕ and Bd→ϕKsBd→ϕKs suggests mt′≈(400–600) GeVmt′≈(400–600) GeV. Such heavy masses point to the tantalizing possibility that the 4th family plays an important role in the electroweak symmetry breaking. The spectacular performance of the two asymmetric B-factories allowed us to reach an important milestone in our understanding of CP-violation phenomena. For the first time it was established that the observed CP-violation in the B and K systems was indeed accountable by the single, CP-odd, Kobayashi–Maskawa phase in the CKM matrix [1] and [2]. In particular, the time dependent CP -asymmetry in the gold-plated B0→ψKsB0→ψKs can be accounted for by the Standard Model (SM) CKM-paradigm to an accuracy of around 15% [3] and [4]. It has then become clear that the effects of a beyond the standard model (BSM) phase can only be a perturbation. Nevertheless, in the past few years as more data were accumulated and also as the accuracy in some theoretical calculations was improved it has become increasingly apparent that several of the experimental results are difficult to reconcile within the SM with three generations [SM3] [5] and [6]. It is clearly important to follow these indications and to try to identify the possible origin of these discrepancies especially since they may provide experimental signals for the LHC which is set to start quite soon. While at this stage many extensions of the SM could be responsible, in this Letter, we will make the case that an addition of a fourth family of quarks [7], [8], [9], [10] and [11] provides a rather simple explanation for the pattern of deviations that have been observed [12]. In fact we will show that the data suggests that the charge 2/3 quark of this family needs to have a mass in the range of (400–600) GeV [13].

Scalar Leptoquarks and the Rare B Meson Decays

We study some rare decays of B meson involving the quark level transition \(b \rightarrow q l^+l^-~(q=d,s)\) in the scalar leptoquark model. We constrain the leptoquark parameter space using the recently measured branching ratios of \(B_{s,d} \rightarrow \mu ^+ \mu ^-\) processes. Using such parameters, we obtain the branching ratios, direct CP violation parameters and isospin asymmetries in \(B \rightarrow K \mu ^+ \mu ^-\) and \(B \rightarrow \pi \mu ^+ \mu ^-\) processes. We also obtain the branching ratios for some lepton flavour violating decays \(B \rightarrow l_i^+ l_j^-\). We find that the various anomalies associated with the isospin asymmetries of \(B \rightarrow K \mu ^+ \mu ^-\) process can be explained in the scalar leptoquark model.

Explaining the RK and RD(*) anomalies with vector leptoquarks

Recently, the B factories BABAR and Belle as well as the LHCb experiment have reported several anomalies in the semileptonic B meson decays, such as the R-K and R-D(*) etc. We investigate these deviations by considering the vector leptoquarks relevant for both b -> sl(+)l(-) and b -> cl(-)v(l) transitions. The leptoquark parameter space is constrained by using the experimentally measured branching ratios of B-s -> l(broken vertical bar) l(-), (B) over bar -> X(s)l(broken vertical bar) l(-) (v (v) over bar), and B-u(broken vertical bar) -> l(broken vertical bar) v(1) processes. Using the constrained leptoquark couplings, we compute the branching ratios, forward- backward asymmetries, tau, and D* polarization parameters in the (B) over bar -> D-(*) l (v) over bar (1)processes. We find that the vector leptoquarks can explain both the R-D(*) and R-K anomalies, simultaneously. Furthermore, we study the rare leptonic B-u,c(*) -> l (v) over bar decay processes in this model.

Study of FCNC mediated rare

We study the rare semileptonic and radiative leptonic B_s decays in the universal extra dimension model. In this scenario, with a single extra dimension, there exists only one new parameter beyond those of the standard model, which is the inverse of the compactification radius R. We find that with the additional contributions due to the KK modes the branching ratios of the rare B_s decays are enhanced from their corresponding standard model values and the zero point of the forward backward asymmetries are shifted towards the left.

B_s

R. Mohanta and A. K. Giri 1 School of Physics, University of Hyderabad, Hyderabad 500 046, India 2 Department of Physics, Punjabi University, Patiala 147002, India Abstract We investigate the effect of unparticles in the pure annihilation type decays B → D s φ and D s K ∗0. Since these decays have only annihilation contributions their branching ratios are expected to be very small in the standard model and the direct CP asymmetry parameters to be zero. We find that due to the unparticle effect these branching ratios can be significantly enhanced from their standard model values. Furthermore, sizable nonzero direct CP violation could also be possible in these channels due to the presence of intrinsic CP conserving phase in the unparticle propagator.

decays in a single universal extra dimension scenario

We study the effect of scalar leptoquarks in the lepton flavor violating

Possible signatures of unparticles in rare annihilation type B decays

B

Lepton flavor violating B meson decays via a scalar leptoquark

meson decays induced by the flavor-changing transitions

Study of FCNC mediated Z boson effectin the semileptonic rare baryonic decays Λ b → Λl + l -

b\ensuremath{\rightarrow}q{l}_{i}^{+}{l}_{j}^{\ensuremath{-}}

Neutrino mixing matrices with relatively large θ 13 and with texture one-zero

with