Reduction of Charm Quark Mass Scheme Dependence in Bˉ→Xsγ\bar B \to X_s \gamma at the NNLL Level

The uncertainty of the theoretical prediction of the $\bar B \to X_s \gamma$ branching ratio at NLL level is dominated by the charm mass renormalization scheme ambiguity. In this paper we calculate those NNLL terms which are related to the renormalization of $m_c$, in order to get an estimate of the corresponding uncertainty at the NNLL level. We find that these terms significantly reduce (by typically a factor of two) the error on ${BR}(\bar B \to X_s \gamma)$ induced by the definition of $m_c$. Taking into account the experimental accuracy of around 10% and the future prospects of the $B$ factories, we conclude that a NNLL calculation would increase the sensitivity of the observable $\bar B \to X_s \gamma$ to possible new degrees of freedom beyond the SM significantly.Comment: 13 pages including 3 figure

Genetic characterization of grape varieties in Armenia

Historically, grapes have been an important crop in Armenia. The world‘s earliest known wine-making facility has been discovered in Armenia during excavation of Areni-1 cave between 2007-2010, and analysis has confirmed the discovery of the oldest complete wine production facility ever discovered dated between 6,000 B.C. and 8,000 B.C. Having thousands of years history, Armenian native grape varieties are characterized with high genetic diversity and variability. The study has evaluated the genetic diversity of the Armenian grapevine cultivars within the Vitis collection of the Scientific Center of Fruit Growing, Viticulture and Wine-making (Merdzavan, Armenia) and analysed the relationships of this genetic pool with the international varieties registered in European Vitis Database. The analysis of 59 accessions of grapevines from Armenia at 23 microsatellite markers generated 336 alleles. The most informative locus turned out to be VVS2 (21 alleles, PI = 0.016). Twelve cases of identical genotypes and five cases of homonymy among studied genotypes were identified. The genetic profiles of 28 accessions were unique. Most of them belonged to autochthonous varieties. Genetic analyses tools are highly contributing to the identification and inventory of existing grape varieties. The data generated proves the importance of molecular characterization of grapevines in Armenia especially old ones to support effective preservation of rich diversity of Armenian grape varieties and clones

Spectrum of surface-mode contributions to the excitation probability for electron beam interacting with sharp-edged dielectric wedges

The interaction of a nonrelativistic charged particle beam, travelling parallel to the surface of a sharp-edged dielectric wedge is analyzed. The general expressions for excitation probability are obtained for a beam moving along the direction of a symmetry axis, either outside or inside the dielectric wedge. The dielectric function of the medium is assumed to be isotropic, and numerical results are given for the materials of experimental interest.Comment: LaTeX 2.09, 15 pages, 10 figure

Optimal refrigerator

We study a refrigerator model which consists of two $n$-level systems interacting via a pulsed external field. Each system couples to its own thermal bath at temperatures $T_h$ and $T_c$, respectively ($\theta\equiv T_c/T_h<1$). The refrigerator functions in two steps: thermally isolated interaction between the systems driven by the external field and isothermal relaxation back to equilibrium. There is a complementarity between the power of heat transfer from the cold bath and the efficiency: the latter nullifies when the former is maximized and {\it vice versa}. A reasonable compromise is achieved by optimizing the product of the heat-power and efficiency over the Hamiltonian of the two system. The efficiency is then found to be bounded from below by $\zeta_{\rm CA}=\frac{1}{\sqrt{1-\theta}}-1$ (an analogue of the Curzon-Ahlborn efficiency), besides being bound from above by the Carnot efficiency $\zeta_{\rm C} = \frac{1}{1-\theta}-1$. The lower bound is reached in the equilibrium limit $\theta\to 1$. The Carnot bound is reached (for a finite power and a finite amount of heat transferred per cycle) for $\ln n\gg 1$. If the above maximization is constrained by assuming homogeneous energy spectra for both systems, the efficiency is bounded from above by $\zeta_{\rm CA}$ and converges to it for $n\gg 1$.Comment: 12 pages, 3 figure

Towards next-to-next-to-leading-log accuracy for the width difference in the Bs−B¯s system: fermionic contributions to order (mc/mb)⁰ and (mc/mb)¹

We calculate a class of three-loop Feynman diagrams which contribute to the next-to-next-to-leading logarithmic approximation for the width difference ΔΓs in the B s −B ¯ s system. The considered diagrams contain a closed fermion loop in a gluon propagator and constitute the order αs2Nf, where Nf is the number of light quarks. Our results entail a considerable correction in that order, if ΔΓs is expressed in terms of the pole mass of the bottom quark. If the MS ¯ scheme is used instead, the correction is much smaller. As a result, we find a decrease of the scheme dependence. Our result also indicates that the usually quoted value of the NLO renormalization scale dependence underestimates the perturbative error

Proton induced reactions on 114Sn and 120Sn targets at energies up to 18 MeV

We measure cross sections of proton-induced reactions on tin up to energies of 18 MeV using the stacked-foil activation technique, and report first experimental values for 114Sn(p,{\alpha})111In, {^{120}}Sn(p,{\alpha})117gIn, and 114Sn(p,x)113Sn reactions. Measured cross sections have been compared to existing experimental values and numerical calculations based on Talys1.95. Our data are in good agreement with all previous experiments, and also with Talys1.95 results except for 120Sn(p,{\alpha})117m,gIn reactions where the numerical calculations are shifted to higher energies. We also measure isomeric cross section ratios for 117m,gIn and 120m,gSb pairs as functions of the incident proton energy.Comment: 21 pages, 9 figures, 3 table