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Sep 17, 2013
09/13

by
G. Calderon

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Nonleptonic two body B decays including radially excited $\pi(1300)$ or $\rho(1450)$ mesons in the final state are studied using the framework of generalized naive factorization approach. Branching ratios and CP asymmetries of $B\to P\pi(1300)$, $B\to V\pi(1300)$, $B\to P\rho(1450)$ and $B\to V\rho(1450)$ decays are calculated, where P and V stand for pseudoscalar and vector charmless mesons. Form factors for $B\to \pi(1300)$ and $B\to \rho(1450)$ transitions are estimated in the improved...

Source: http://arxiv.org/abs/1003.4521v1

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2.5K

May 4, 2009
05/09

by
Sofronio G. Calderón

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Book digitized by Google from the library of the University of Michigan and uploaded to the Internet Archive by user tpb.

Source: http://books.google.com/books?id=f_WjwqRpW18C&oe=UTF-8

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Sep 14, 2008
09/08

by
Sofronio G. Calderón

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Book digitized by Google from the library of the University of Michigan and uploaded to the Internet Archive by user tpb.

Source: http://books.google.com/books?id=RDQ3NIVTt8kC&oe=UTF-8

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Sep 15, 2008
09/08

by
Sofronio G. Calderón

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Book digitized by Google from the library of the University of Michigan and uploaded to the Internet Archive by user tpb.

Source: http://books.google.com/books?id=lUZBhFHyePQC&oe=UTF-8

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Sep 17, 2013
09/13

by
G. Calderon; G. Lopez Castro

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In the standard model, the top quark decay width \Gamma_t is computed from the exclusive t -> bW decay. We argue in favor of using the three body decays t-> bf_i\bar{f}_j to compute \Gamma_t as a sum over these exclusive modes. As dictated by the S-matrix theory, these three body decays of the top quark involve only asymptotic states and incorporate the width of the W boson resonance in a natural way. The convolution formula (CF) commonly used to include the finite width effects is found...

Source: http://arxiv.org/abs/hep-ph/0108088v3

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Sep 22, 2013
09/13

by
G. Calderon; G. Lopez Castro

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We update the determination of |V_us| using semielectronic and semimuonic decays of K mesons. A modest improvement of 15% with respect to its present value is obtained for the error bar of this matrix element when we combine the four available semileptonic decays. The combined effects of long-distance radiative corrections and nonlinear terms in the vector form factors can decrease the value of |V_us| by up to 1%. Refined measurements of the decay widths and slope form factors in the semimuonic...

Source: http://arxiv.org/abs/hep-ph/0111272v1

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Sep 22, 2013
09/13

by
G. Calderon; D. Delepine; G. Lopez Castro

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Based on the description of unstable $K_{L,S}$ particles in quantum field theory (QFT), we compute the time-dependent probabilities for transitions between asymptotic states in $\tau^{\pm} \to [\pi^+\pi^-]_K\pi^{\pm}\nu$ decays, where the pair $[\pi^+\pi^-]_K$ is the product of (intermediate state) neutral kaon decays. Then we propose a definition of $\tau$ decays into $K_L$ and $K_S$ states, which reflects into the cancellation between their CP rate asymmetries, thus solving in a natural way...

Source: http://arxiv.org/abs/hep-ph/0702282v1

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Sep 18, 2013
09/13

by
G. Calderon; J. H. Munoz; C. E. Vera

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We present a systematic study of exclusive charmless nonleptonic two-body B decays including axial-vector mesons in the final state. We calculate branching ratios of B\to PA, VA and AA decays, where A, V and P denote an axial-vector, a vector and a pseudoscalar meson, respectively. We assume naive factorization hypothesis and use the improved version of the nonrelativistic ISGW quark model for form factors in B\to A transitions. We include contributions that arise from the effective \Delta B=1...

Source: http://arxiv.org/abs/0705.1181v2

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Sep 23, 2013
09/13

by
G. Calderon; J. H. Munoz; C. E. Vera

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Axial-vector mesons $a_1(1260)$, $f_1(1285)$, $h_1(1170)$, $K_1(1270)$, and $K_1(1400)$ can be produced in semileptonic $\tau\to A P \nu_{\tau}$ decays, where $P$ stands for the pseudoscalar mesons $\pi$ or $K$. We calculate the branching ratios based in a meson dominance model. The exclusive channels $\tau^-\to a_1(1260)^-\pi^0\nu$, $\tau^-\to a_1(1260)^0\pi^-\nu$, and $\tau^-\to h_1(1170)\pi^-\nu$ turn out to be of order ${\cal O}(10^{-3})$, the channel $\tau^-\to f_1(1285)\pi^-\nu$ of order...

Source: http://arxiv.org/abs/1212.1534v2

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Sep 23, 2013
09/13

by
E. Cabrera-Granado; E. Díaz; Oscar G. Calderón

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We study slow light performance of molecular aggregates arranged in nanofilms by means of coherent population oscillations (CPO). The molecular cooperative behavior inside the aggregate enhances the delay of input signals in the GHz range in comparison with other CPO-based devices. Moreover, the problem of residual absorption present in CPO processes, is removed. We also propose an optical switch between different delays by exploiting the optical bistability of these aggregates.

Source: http://arxiv.org/abs/1110.4518v1

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Sep 21, 2013
09/13

by
G. Calderon; J. -M. Gerard; J. Pestieau; J. Weyers

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A Regge model calculation relates the strong phase in $B \to DK$ to that in $B\to D\pi$. This provides a significant test of a hadronic picture of final state interactions in B decays.

Source: http://arxiv.org/abs/hep-ph/0311163v1

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Jul 20, 2013
07/13

by
Sonia Melle; Oscar G. Calderon; Gerald G. Fuller; Miguel A. Rubio

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We used scattering dichroism to study the combined effects of viscous and magnetic forces on the dynamics of dipolar chains induced in magnetorheological suspensions under rotating magnetic fields. We found that the chains adjust their size to rotate synchronously with the field but with a constant phase lag. Two different behaviors for the dichroism (proportional to the total number of aggregated particles) and the phase lag are found below or above a critical frequency. We obtained a linear...

Source: http://arxiv.org/abs/cond-mat/0107070v1

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Sep 23, 2013
09/13

by
M. A. Antón; F. Carreño; Óscar G. Calderón; Sonia Melle; Francisco Arrieta-Yáñez

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We present a theoretical study of the slow and fast light propagation in semiconductor optical amplifiers based on coherent population oscillations. By modulating the injection current to force the population oscillations we can modify the delay or advancement of light signals. Specifically, it is shown that the relative phase of the optical signal to the bias current modulations can be used as a knob for changing light propagation from delay to advancement. In addition, we analyze the effect...

Source: http://arxiv.org/abs/0903.1545v1

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Sep 19, 2013
09/13

by
V. A. Malyshev; F. Carreño; M. A. Antón; Oscar G. Calderón; F. Domínguez-Adame

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We carry out a theoretical study of the collective spontaneous emission (superradiance) from an ultrathin film comprised of three-level atoms with $V$-configuration of the operating transitions. As the thickness of the system is small compared to the emission wavelength inside the film, the local-field correction to the averaged Maxwell field is relevant. We show that the interplay between the low-frequency quantum coherence within the subspace of the upper doublet states and the local-field...

Source: http://arxiv.org/abs/quant-ph/0302177v1

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Sep 23, 2013
09/13

by
Yunhui Zhu; E. Cabrera-Granado; Oscar G. Calderon; Sonia Melle; Yoshitomo Okawachi; Alexander L. Gaeta; and Daniel J. Gauthier

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We observe competition between the modulation instability (MI) and stimulated Brillouin scattering (SBS) in a 9.2-GHz broadband SBS slow light device, in which a standard 20-km-long single-mode LEAF fibre is used as the SBS medium. We find that MI is dominant and depletes most of the pump power when we use an intense pump beam at ~1.55 {\mu}m, where the LEAF fibre is anomalously dispersive. The dominance of the MI in the LEAF-fibre-based system suppresses the SBS gain, degrading the SBS slow...

Source: http://arxiv.org/abs/1006.5380v1