Development of giant freshwater prawn broodstock

The commercial success of a giant freshwater prawn (Macrobrachium rosenbergii) hatchery depends upon the uninterrupted supply of the desired quantity and quality of broodstock. This study was an attempt to develop the broodstock near a hatchery, to be used for seed production throughout the year. The hatchery produced seed were stocked at the rate of 3/m2 after initial pond preparation. The prawns were fed with a pelleted diet (3 mm size) prepared by using locally available feed ingredients. The seed had an initial weight of 0.30 g and attained an average weight of 92.0 g and 62.0 g in males and females, respectively, within 11 months. Berried prawns were observed starting from the month of June (5%), after six months of stocking, with a maximum in September (60%). The percentage of berried prawns increased from June to September when the water temperature was optimum and decreased from December when it got cold. The broodstock developed in this experiment could be used in the hatchery after six months of stocking, and brooders could be used to produce seed for two seasons before being sold in the market

Study of some B_s to f_0(980) decays in the fourth generation model

We study some non leptonic and semileptonic decays of $B_s$ meson into a final scalar meson $f_0(980)$ in the fourth quark generation model. Since the $f_0(980)$ meson is dominantly composed of ($s \bar s$) pair, the mixing induced CP asymmetry in the decay mode $B_s \to J/\psi f_0(980)$ would {\it a priori} give $\sin 2 \beta_s$, where $\beta_s$ is the $B_s-\bar B_s$ mixing phase. In the standard model this asymmetry is expected to be vanishingly small. We find that in the fourth generation model a large mixing induced CP asymmetry could be possible for this process. Similarly the branching ratios of the rare semileptonic decays $B_s \to f_0(980) l^+ l^-$ and $B_s \to f_0(980) \nu \bar \nu$ are found to be enhanced significantly from their corresponding standard model values.Comment: 18 pages, 5 figures, minor changes in the text, added few references, to appear in Phys. Rev.

Leptoquark effects on b→sννˉb \to s \nu \bar{\nu} and B→Kl+l−B \to K l^+ l^- decay processes

We study the rare semileptonic decays of $B$ mesons induced by $b \to s \nu \bar{\nu}$ as well as $b \to s l^+ l^-$ transitions in the scalar leptoquark model where the leptoquarks transform as $(3,2,7/6)$ and $(3,2,1/6)$ under the standard model gauge group. The leptoquark parameter space is constrained using the most recent experimental results on ${\rm Br}(B_s \rightarrow \mu^+ \mu^-)$ and ${\rm Br}(B_d \to X_s \mu^+ \mu^-)$ processes. Considering only the baryon number conserving leptoquark interactions, we estimate the branching ratios for the exclusive $\bar{B} \rightarrow \bar{K}^{(*)} \nu \bar{\nu}$ and inclusive $B \rightarrow X_s \nu \bar{\nu}$ decay processes by using the constraint parameters. We also obtain the low recoil (large lepton invariant mass, i.e., $q^2 \sim m^2_b$) predictions for the angular distribution of $\bar B \rightarrow \bar{K} l^+ l^-$ process and several other observables including the flat term and lepton flavour non-universality factor in this model.Comment: 24 pages, 10 figures, version to appear in New J. Phy