Towards the NNLL precision in Bˉ→Xsγ\bar B \to X_s \gamma

The present NLL prediction for the decay rate of the rare inclusive process $\bar B \to X_s \gamma$ has a large uncertainty due to the charm mass renormalization scheme ambiguity. We estimate that this uncertainty will be reduced by a factor of 2 at the NNLL level. This is a strong motivation for the on-going NNLL calculation, which will thus significantly increase the sensitivity of the observable $\bar B \to X_s \gamma$ to possible new degrees of freedom beyond the SM. We also give a brief status report of the NNLL calculation.Comment: 5 pages, 2 figures, contribution to the proceedings of EPS-HEP 200

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

Photon cooling: linear vs nonlinear interactions

Linear optics imposes a relation that is more general than the second law of thermodynamics: For modes undergoing a linear evolution, the full mean occupation number (i.e. photon number for optical modes) does not decrease, provided that the evolution starts from a (generalized) diagonal state. This relation connects to noise-increasing (or heating), and is akin to the second law and holds for a wide set of initial states. Also, the Bose-entropy of modes increases, though this relation imposes additional limitations on the initial states and on linear evolution. We show that heating can be reversed via nonlinear interactions between the modes. They can cool -- i.e. decrease the full mean occupation number and the related noise -- an equilibrium system of modes provided that their frequencies are different. Such an effect cannot exist in energy cooling, where only a part of an equilibrium system is cooled. We describe the cooling set-up via both efficiency and coefficient of performance and relate the cooling effect to the Manley-Rowe theorem in nonlinear optics.Comment: 16 pages, 9 figures; second extended version to appear in Physical Review

Computation of Microcanonical Entropy at Fixed Magnetization Without Direct Counting

We discuss a method to compute the microcanonical entropy at fixed magnetization without direct counting. Our approach is based on the evaluation of a saddle-point leading to an optimization problem. The method is applied to a benchmark Ising model with simultaneous presence of mean-field and nearest-neighbour interactions for which direct counting is indeed possible, thus allowing a comparison. Moreover, we apply the method to an Ising model with mean-field, nearest-neighbour and next-nearest-neighbour interactions, for which direct counting is not straightforward. For this model, we compare the solution obtained by our method with the one obtained from the formula for the entropy in terms of all correlation functions. This example shows that for general couplings our method is much more convenient than direct counting methods to compute the microcanonical entropy at fixed magnetization

Artistic creativity of martiros saryan as the indicator of national self-identification of the personality in a multicultural space: features of methodology of a retrospective research

In this article, the life and works of the famous Armenian artist, founder of the modern Armenian school of painting Martiros Saryan (1880-1972) are analyzed in the context of the influence of Russian and Armenian culture during the Russian period of his activity. In this retrospective analysis of the life and works of the artist, it is proposed to use the new indicator, which is Russian or the Middle East countries place names being included in the titles of works by the artist. On the basis of the analysis of Russian archival sources and the analytical research of content, it is established that, in Russia, the interest of the artist during the first period of his life and study was mainly on subjects reflecting the life of the Armenian diaspora in the south of Russia. Landscapes were mainly represented against the background in which the artist spent his childhood. During the time which he spent in Moscow, interest in Russian culture was connected with the recognition of the contribution of teachers of the School of Painting, Sculpture and Architecture in the development of the Russian art school and world culture. Saryan has shown the aspiration to seize this particular technic of painting, at the same time he had the original vision of the world. Keywords: methodology, personality, geographical indicators, Martiros Saryan, culture,regional archiv

Photo-induced processes in collagen-hypericin system revealed by fluorescence spectroscopy and multiphoton microscopy

Collagen is the main structural protein and the key determinant of mechanical and functional properties of tissues and organs. Proper balance between synthesis and degradation of collagen molecules is critical for maintaining normal physiological functions. In addition, collagen influences tumor development and drug delivery, which makes it a potential cancer therapy target. Using second harmonic generation, two-photon excited fluorescence microscopy, and spectrofluorimetry, we show that the natural pigment hypericin induces photosensitized destruction of collagen-based tissues. We demonstrate that hypericin–mediated processes in collagen fibers are irreversible and may be used for the treatment of cancer and collagen-related disorders