Probing new physics in B -> f_0(980) K decays

We study the hadronic decay modes $B^{\pm(0)} \to f_0(980) K^{\pm(0)}$, involving a scalar and a pseudoscalar meson in the final state. These decay modes are dominated by the loop induced $b \to s \bar q q(q=s,u,d)$ penguins along with a small $b \to u$ tree level transition (for $B^+ \to f_0 K^+$) and annihilation diagrams. Therefore, the standard model expectation of direct CP violation is negligibly small and the mixing induced CP violation parameter in the mode $B^0 \to f_0 K_S$ is expected to give the same value of $\sin(2\beta)$, as extracted from $B^0 \to J/\psi K_S$ but with opposite sign. Using the generalized factorization approach we find the direct CP violation in the decay mode $B^+ \to f_0 K^+$ to be of the order of few percent. We then study the effect of the R-parity violating supersymmetric model and show that the direct CP violating asymmetry in $B^+ \to f_0(980) K^+$ could be as large as $\sim 80$ and the mixing induced CP asymmetry in $B^0 \to f_0 K_S$ (i.e., $-S_{f_0 K_S}$) could deviate significantly from that of $\sin(2 \beta)_{J/\psi K_S}$.Comment: 18 pages, 5 figures, version to appear in Phys. Rev.

Weak phase information from the color suppressed B_d^0 -> D^{*0} K^{*0} modes

The decay channels $B_d^0 \to D^{*0} K^{*0}$ are investigated for extracting weak $CKM$ phase information. These channels are described by color-suppressed tree diagrams only and are free from penguin contributions. The branching ratios for these channels are found to be $\sim \cal O$ $(10^{-5} - 10^{-6})$ which can be measured at the currently running $B$ factories. The method presented here may be well-suited to determine the phase $\gamma$.Comment: 11 pages, revised extensively, version to appear in Phys. Rev.

Possibility of extracting the weak phase γ\gamma from Λb→ΛD0\Lambda_b \to \Lambda D^0 decays

We explore the possibility of extracting the weak phase $\gamma$ from pure tree decays $\Lambda_b \to \Lambda (D^0, \bar{D^0}, D^0_{CP})$ in a model independent way. The CP violating weak phase $\gamma$ can be determined cleanly, without any hadronic uncertainties, as these decay modes are free from the penguin pollutions. Furthermore, neither tagging nor time dependent studies are required to extract the angle $\gamma$ with these modes.Comment: 12 pages, LaTex, Minor changes in the text, version to appear in Phys. Rev.

Responsible fisheries and sustainable aquaculture - A pledge for 21st century

The beginning of the new millennium century the next millennium looks not only to secure enough food for the existing population but also to provide a guarantee to sustained food availability for future generation. Though scientific aquaculture has substituted the traditional practices in a big way, it cannot be fully relied upon to meet the demands of future generation. This is due to the fact that continued over fishing, heavy intensification of farms in localized areas, degradation of aquatic environment etc will put insurmountable strain on the fishery sector which is capable enough for a sustainable food supply

Effect of FCNC mediated Z boson on lepton flavor violating decays

We study the three body lepton flavor violating (LFV) decays $\mu^- \to e^- e^+ e^-$, $\tau^- \to l_i^- l_j^+ l_j^-$ and the semileptonic decay $\tau \to \mu \phi$ in the flavor changing neutral current (FCNC) mediated $Z$ boson model. We also calculate the branching ratios for LFV leptonic B decays, $B_{d,s} \to \mu e$, $B_{d,s} \to \tau e$, $B_{d,s} \to \tau \mu$ and the conversion of muon to electron in Ti nucleus. The new physics parameter space is constrained by using the experimental limits on $\mu^- \to e^- e^+ e^-$ and $\tau^- \to \mu^- \mu^+ \mu^-$. We find that the branching ratios for $\tau \to eee$ and $\tau \to \mu \phi$ processes could be as large as $\sim {\cal O}(10^{-8})$ and ${\rm Br}B_{d,s} \to \tau \mu, \tau e) \sim {\cal O}(10^{-10})$. For other LFV B decays the branching ratios are found to be too small to be observed in the near future.Comment: 15 pages, 8 figures, typos corrected, one more section added, version to appear in EPJ

Double-Lepton Polarization Asymmetries and Branching Ratio in B \rar K_{0}^{*}(1430) l^+ l^- transition from Universal Extra Dimension Model

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.Comment: 12 Pages, 15 Figures and 1 Tabl

SM with four generations: Selected implications for rare B and K decays

We extend our recent work and study implications of the Standard Model with four generations (SM4) for rare B and K decays. We again take seriously the several 2-3 $\sigma$ anomalies seen in B, $B_s$ decays and interpret them in the context of this simple extension of the SM. SM4 is also of course of considerable interest for its potential relevance to dynamical electroweak symmetry breaking and to baryogenesis. Using experimental information from processes such as $B \to X_s \gamma$, $B_d$ and $B_s$ mixings, indirect CP-violation from $K_L \to \pi \pi$ etc along with oblique corrections, we constrain the relevant parameter space of the SM4, and find $m_{t'}$ of about 400-600 GeV with a mixing angle $| V_{t'b}^*V_{t's}|$ in the range of about (0.05 to 1.4)$\times 10^{-2}$ and with an appreciable CP-odd associated phase, are favored by the current data. Given the unique role of the CP asymmetry in $B_s \to \psi \phi$ due to its gold-plated nature, correlation of that with many other interesting observables, including the semileptonic asymmetry ($A_{SL}$) are studied in SM4. We also identify several processes, such as $B \to X_s \nu \bar\nu$, $K_L \to \pi^0 \nu \bar \nu$ etc, that are significantly different in SM4 from the SM. Experimentally the very distinctive process $B_s\to \mu^+\mu^-$ is also discussed; the branching ratio can be larger or smaller than in SM, $(3.2 \to 4.2)\times 10^{-9}$, by a factor of ${\cal{O}}(3)$.Comment: v2: 49 pages, 20 eps figures, Corrected some typos, added few references and minor changes with regard to direct CP in K pi. Also some added information to facilitate direct comparison with Buras et al, arXiv:1002.2126

Neutral Gauge Boson Contributions to the Dimuon Charge Asymmetry in B Decays

Recently, the D0 Collaboration measured the CP-violating like-sign dimuon charge asymmetry in neutral B decays, finding a 3.2sigma difference from the standard-model (SM) prediction. A non-SM charge asymmetry a_sl^s suggests a new-physics (NP) contribution to Bs-Bsbar mixing. In this case, in order to explain the measured value of a_sl^s within its 1sigma range, NP must be present in Gamma_12^s, the absorptive part of the mixing. In this paper, we examine whether such an explanation is possible in models with flavor-changing Z (ZFCNC) or Z' (Z'FCNC) gauge bosons. The models must also reproduce the measured values of the indirect CP asymmetry S_psi-phi in Bs -> J/psi phi, and Delta Gamma_s, the Bs-Bsbar width difference. We find that the ZFCNC model cannot reproduce the present measured values of S_psi-phi and a_sl^s within their 1sigma ranges. On the other hand, in the Z'FCNC model, the values of all three observables can be simultaneously reproduced.Comment: 18 pages, 7 figures, JHEP format. Some ZFCNC equations corrected, ZFCNC analysis redone, references added, conclusions unchange

FCNC Top Quark Decays in Extra Dimensions

The flavor changing neutral top quark decay t -> c X is computed, where X is a neutral standard model particle, in a extended model with a single extra dimension. The cases for the photon, X= \gamma$, and a Standard Model Higgs boson, X = H, are analyzed in detail in a non-linear$R_\xi gauge. We find that the branching ratios can be enhanced by the dynamics originated in the extra dimension. In the limit where 1/R >> ->, we have found Br(t -> c \gamma) \simeq 10^{-10} for 1/R = 0.5 TeV. For the decay t -> c H, we have found Br(t -> cH) \simeq 10^{-10} for a low Higgs mass value. The branching ratios go to zero when 1/R -> \infty.Comment: Accepted to be published in the Europ. Phys. Jour. C; 16 pages, 2 figure

Bounds on Heavy-to-Heavy Mesonic Form Factors

We provide upper and lower bounds on the form factors for B -> D, D^* by utilizing inclusive heavy quark effective theory sum rules. These bounds are calculated to leading order in Lambda_QCD/m_Q and alpha_s. The O(alpha_s^2 beta_0) corrections to the bounds at zero recoil are also presented. We compare our bounds with some of the form factor models used in the literature. All the models we investigated failed to fall within the bounds for the combination of form factors (omega^2 - 1)/(4 omega)|omega h_{A2}+h_{A3}|^2.Comment: 27 pages, 10 figure