Lepton polarization correlations in B→K∗τ−τ+B \to K^* \tau^- \tau^+

In this work we will study the polarizations of both leptons ($\tau$) in the decay channel $B\to K^* \tau^- \tau^+$. In the case of the dileptonic inclusive decay $B\to K^* \ell^- \ell^+$, where apart from the polarization asymmetries of single lepton $\ell$, one can also observe the polarization asymmetries of both leptons simultaneously. If this sort of measurement is possible then we can have, apart from decay rate, FB asymmetry and the six single lepton polarization asymmetries (three each for $\ell^-$ and $\ell^+$), nine more double polarization asymmetries. This will give us a very useful tool in more strict testing of SM and the physics beyond. We discuss the double polarization asymmetries of $\tau$ leptons in the decay mode $B\to K^* \tau^- \tau^+$ within the SM and the Minimal Supersymmetric extensions of it.Comment: 21 pages, 21 figures; version to match paper to appear in PR

Comparison of ground and aerial application of fungicide for control of Ascochyta blight in chickpeas

Non-Peer ReviewedAscochyta rabiei control from aerial and ground application was assessed near Saskatoon in 2003 and 2004. Each year, a site of about 12 ha was seeded to kabuli (cv. CDC Xena) chickpeas. At the first sign of disease, applications of fungicide were commenced and maintained at approximately 10-day intervals. In 2003, four applications (two with Headline (pyraclostrobin), two with Lance (boscalid)) were conducted. In 2004, the last Lance application was not done. Aerial application was made using a Cessna AgTruck applying 37 L/ha using CP nozzles emitting a spray with a VMD of approximately 271 μm. Ground applications were conducted using a Melroe SpraCoupe applying 100 L/ha using XR8003 nozzles with a VMD of approximately 246 μm. Disease ratings were done throughout the season, and seed yields were taken at crop maturity. Disease incidence progressed to 80 to 90% in the untreated plots, and fungicide application reduced disease incidence (to 20 to 30%) and increased seed yield in both years. Disease incidence and seed yield were not affected by application method in either season

Electromagnetic Decays of Heavy Baryons

The electromagnetic decays of the ground state baryon multiplets with one heavy quark are calculated using Heavy Hadron Chiral Perturbation Theory. The M1 and E2 amplitudes for S^{*}--> S gamma, S^{*} --> T gamma and S --> T gamma are separately computed. All M1 transitions are calculated up to O(1/Lambda_chi^2). The E2 amplitudes contribute at the same order for S^{*}--> S gamma, while for S^{*} --> T gamma they first appear at O(1/(m_Q \Lambda_\chi^2)) and for S --> T gamma are completely negligible. The renormalization of the chiral loops is discussed and relations among different decay amplitudes are derived. We find that chiral loops involving electromagnetic interactions of the light pseudoscalar mesons provide a sizable enhancement of these decay widths. Furthermore, we obtain an absolute prediction for the widths of Xi^{0'(*)}_c--> Xi^{0}_c gamma and Xi^{-'(*)}_b--> Xi^{-}_b gamma. Our results are compared to other estimates existing in the literature.Comment: 17 pages, 3 figures, submitted to Phys. Rev.

The magnetic moments of 'Lambda_b' and 'Lambda_c' baryons in light cone QCD sum rules

Using the most general form of the interpolating currents of heavy baryons, the magnetic moments of heavy baryons "Lambda_Q (Q=b,c)" are calculated in framework of the light cone QCD sum rules. A comparison of our results on magnetic moments with the existing theoretical results calculated in various other frameworks are presented.Comment: 14 pp, 6 figures (postscript formatted), LaTex formatte

Interlayer Exchange Coupling Mediated by Valence Band Electrons

The interlayer exchange coupling mediated by valence band electrons in all-semiconductor IV-VI magnetic/nonmagnetic superlattices is studied theoretically. A 3D tight-binding model, accounting for the band and magnetic structure of the constituent superlattice components is used to calculate the spin-dependent part of the total electronic energy. The antiferromagnetic coupling between ferromagnetic layers in EuS/PbS superlattices is obtained, in agreement with the experimental evidences. The results obtained for the coupling between antiferromagnetic layers in EuTe/PbTe superlattices are also presented.Comment: 8 pages, 6 figures, to be submitted to Phys.Rev.

CKM Favored Semileptonic Decays of Heavy Hadrons at Zero Recoil

We study the properties of Cabibbo-Kobayashi-Maskawa (CKM) favored semileptonic decays of mesons and baryons containing a heavy quark at the point of no recoil. We first use a diagrammatic analysis to rederive the result observed by earlier authors that at this kinematic point the $B$ meson decays via $b\to c$ transitions can only produce a $D$ or $D^*$ meson. The result is generalized to include photon emissions which violate heavy quark flavor symmetry. We show that photons emitted by the heavy quarks and the charged lepton are the only light particles that can decorate the decays $\bar{B}\to D(D^*) + \ell\nu$ at zero recoil, and the similar processes of heavy baryons. Implications for the determinations of the CKM parameter $V_{cb}$ are discussed. Also studied in this paper is the connection between our diagrammatic analysis of suppression of particle emission and the formal observation based on weak currents at zero recoil being generators of heavy quark symmetry. We show that the two approaches can be unified by considering the Isgur-Wise function in the presence of an external source.Comment: 27 pages, including 11 figures using macros FEYNMAN.te

Radiative Decays of Excited ΛQ\Lambda_Q Baryons in the Bound State Picture

It is shown that, in the bound state picture, the $\Lambda_c(2593) \to\Lambda_c\gamma$ and $\Lambda_c(2625)\to\Lambda_c\gamma$ decays are severely suppressed. On the other hand, for their bottom counterparts, which are predicted to have masses 5900 and 5926 MeV respectively, may have significant radiative branching ratio. In particular, the $\Lambda_b(5926)\to\Lambda_b\gamma$ mode may even dominate over the strong decay mode. The isospin allowed $\Lambda^{**}_Q\to\Sigma_Q\gamma$ mode is expected to be small.Comment: 8 pages in REVTeX, no figure

Vector and pseudoscalar charm meson radiative decays

Combining heavy quark effective theory and the chiral Lagrangian approach we investigate radiative decays of pseudoscalar $D$ mesons. We first reanalyse $D^{*} \rightarrow D \gamma$ decays within the effective Lagrangian approach using heavy quark spin symmetry, chiral symmetry Lagrangian, but including also the light vector mesons. We then investigate $D \rightarrow V \gamma$ decays and calculate the $D^0 \rightarrow \bar{K}^{*0} \gamma$ and $D^{s+} \rightarrow \rho^+ \gamma$ partial widths and branching ratios.Comment: 21 pages Latex, no figures, IJS-TP-94/19, TUM-31-62/94, NUHEP-TH-94-

One-pion transitions between heavy baryons in the constituent quark model

Single pion transitions of S wave to S wave, P wave to S wave and P wave to P wave heavy baryons are analyzed in the framework of the Heavy Quark Symmetry limit (HQS). We use a constituent quark model picture for the light diquark system with an underlying SU(2N_{f}) X O(3) symmetry to reduce the number of the HQS coupling factors required to describe these transitions. We also use the quantum theory of angular momentum to rewrite the one-pion transitions constituent quark model results in a more general form using the 6j- and 9j-symbols. We finally estimate the decay rates of some single pion transitions between charm baryon states.Comment: Latex, 33 pages including 2 figures (Postscript). Some typos are corrected with minor changes. Two references were added to the final version which will appear in Phy. Rev.

Supersymmetric effects on Forward Backward asymmetries of B→Kℓ+ℓ−B \to K \ell^+ \ell^-

Leptonic and semi-leptonic rare decays of B-mesons are very clean (both theoretically and experimentally) signatures of any new physics beyond the Standard Model (SM). More specifically the decay \btokll has been theoretically observed to be very sensitive to new physics as the Forward Backward (FB) asymmetry in this decay mode vanishes in the SM. Supersymmetry, however, predicts a non-vanishing value of this asymmetry. In this work we will study the polarized lepton pair FB asymmetry, i.e. the FB asymmetry of the lepton when one (or both) final state lepton(s) are polarized. We will study these asymmetries both within the SM and for Supersymmetric corrections to the SM.Comment: 18 pages, RevTeX file including 21 eps figures; version accepted for publication in Phys. Rev. D. Some references adde