Showing papers by "Antonio Pich published in 2011"
Posted Content•
TL;DR: The 2011 Workshop on Precision Measurements of {alpha,sub s} (m{sub Z}) was held at the Max-Planck-Institute for Physics, Munich, February 9-11, 2011 as discussed by the authors.
Abstract: These are the proceedings of the Workshop on Precision Measurements of {alpha}{sub s} held at the Max-Planck-Institute for Physics, Munich, February 9-11, 2011. The workshop explored in depth the determination of {alpha}{sub s}(m{sub Z}) in the {ovr MS} scheme from the key categories where high precision measurements are currently being made, including DIS and global PDF fits, {tau}-decays, electro-weak precision observables and Z-decays, event-shapes, and lattice QCD. These proceedings contain a short summary contribution from the speakers, as well as the lists of authors, conveners, participants, and talks.
81 citations
TL;DR: In this article, the authors analyzed the CP rate asymmetry in this inclusive decay and determined the resulting constraints on the model parameters, and extended the phenomenological analysis of the branching ratio, and examined the influence of resulting correlations on the like-sign dimuon charge asymmetry.
Abstract: In the two-Higgs-doublet model the alignment of the Yukawa matrices in flavour space guarantees the absence of flavour-changing neutral currents at tree level, while introducing new sources for CP violation parametrized in a very economical way [1] This implies potentially large influence in a number of processes, b ! s being a prominent example where rather high experimental and theoretical precision meet We analyze the CP rate asymmetry in this inclusive decay and determine the resulting constraints on the model parameters We demonstrate the compatibility with previously obtained limits [2] Moreover we extend the phenomenological analysis of the branching ratio, and examine the influence of resulting correlations on the like-sign dimuon charge asymmetry in B decays
51 citations
TL;DR: In this paper, the authors constructed the amplitudes that fulfill exact elastic unitarity, account for one-loop chiral perturbation theory contributions and include all $1/{N}_{C}$ leading terms, with the only limitation of considering just the lowest-lying nonet of exchanged resonances.
Abstract: We construct $\ensuremath{\pi}\ensuremath{\pi}$ amplitudes that fulfill exact elastic unitarity, account for one-loop chiral perturbation theory contributions and include all $1/{N}_{C}$ leading terms, with the only limitation of considering just the lowest-lying nonet of exchanged resonances. Within such a scheme, the ${N}_{C}$ dependence of $\ensuremath{\sigma}$ and $\ensuremath{\rho}$ masses and widths is discussed. Robust conclusions are drawn in the case of the $\ensuremath{\rho}$ resonance, confirming that it is a stable meson in the limit of a large number of QCD colors, ${N}_{C}$. Less definitive conclusions are reached in the scalar-isoscalar sector. With the present quality of data, we cannot firmly conclude whether or not the ${N}_{C}=3$ ${f}_{0}(600)$ resonance completely disappears at large ${N}_{C}$ or if it has a subdominant component in its structure, which would become dominant for a number of quark colors sufficiently large.
42 citations
TL;DR: In this paper, the vector form factor of the pion at the next-to-leading order (NLO) in the 1/NC expansion was calculated using the Resonance Chiral Theory Lagrangian.
Abstract: Using the Resonance Chiral Theory Lagrangian, we perform a calculation of the vector form factor of the pion at the next-to-leading order (NLO) in the 1/NC expansion. Imposing the correct QCD short-distance constraints, one fixes the amplitude in terms of the pion decay constant F and resonance masses. Its low momentum expansion determines then the corresponding \( \mathcal{O}\left( {{p^4}} \right) \) and \( \mathcal{O}\left( {{p^6}} \right) \) low-energy chiral couplings at NLO, keeping control of their renormalization scale dependence. At μ0 = 0.77 GeV, we obtain L9(μ0) = (7.9 ± 0.4) ∙ 10−3 and C88(μ0) − C90(μ0) = (−4.6 ± 0.4) ∙ 10−5 .
34 citations
01 Sep 2011
TL;DR: In this article, the QCD analysis of hadronic τ decays is reviewed and a summary of the present phenomenological status is presented, including the determination of α s (m τ 2 ) = 0.338 ± 0.012 from the inclusive τ hadronic width, the measurement of | V u s | through the Cabibbo-suppressed decays of the τ, and the extraction of chiral-perturbation-theory couplings from the spectral tau data.
Abstract: The QCD analysis of hadronic τ decays is reviewed and a summary of the present phenomenological status is presented. The following topics are discussed: the determination of α s ( m τ 2 ) = 0.338 ± 0.012 from the inclusive τ hadronic width, the measurement of | V u s | through the Cabibbo-suppressed decays of the τ, and the extraction of chiral-perturbation-theory couplings from the spectral tau data.
20 citations
01 Jan 2011
TL;DR: In this article, the ALEPH data was used to obtain the dominant correction (∼ 20%) of the perturbative QCD contribution, which can be extracted from the invariant-mass distribution of the final hadrons.
Abstract: where NC = 3 is the number of quark colours and SEW = 1.0201 ± 0.0003 contains the electroweak radiative corrections. The non-perturbative contributions are suppressed by six powers of the τ mass [1] and can be extracted from the invariant-mass distribution of the final hadrons [3]. From the ALEPH data, one obtains δNP = −0.0059± 0.0014 [4]. The dominant correction (∼ 20%) is the perturbative QCD contribution [1] [3]
18 citations
Posted Content•
TL;DR: In this paper, the accurate determination of the strong coupling from tau decay data is briefly reviewed and the present phenomenological status is summarized, and a phenomenological model for strong coupling is presented.
Abstract: The accurate determination of the strong coupling from tau decay data is briefly reviewed. The present phenomenological status is summarized.
12 citations
TL;DR: In this article, an introductory overview of the standard model description of flavour is presented, and the main emphasis is put on present tests of the quark-mixing matrix structure and the phenomenological determination of its parameters.
Abstract: An introductory overview of the Standard Model description of flavour is presented. The main emphasis is put on present tests of the quark-mixing matrix structure and the phenomenological determination of its parameters. Special attention is given to the experimental evidences of CP violation and their important role in our understanding of flavour dynamics.
9 citations
TL;DR: In this paper, the QCD analysis of hadronic tau decays is reviewed and a summary of the present phenomenological status is presented; the following topics are discussed: the determination of alpha_s(m_tau) = 0.338 +- 0.012 from the inclusive tau hadronic width, the measurement of |V_us| through the Cabibbo-suppressed decays of the tau, and the extraction of chiral-perturbation-theory couplings from the spectral tau data.
Abstract: The QCD analysis of hadronic tau decays is reviewed and a summary of the present phenomenological status is presented. The following topics are discussed: the determination of alpha_s(m_tau) = 0.338 +- 0.012 from the inclusive tau hadronic width, the measurement of |V_us| through the Cabibbo-suppressed decays of the tau, and the extraction of chiral-perturbation-theory couplings from the spectral tau data.
3 citations
01 Jan 2011
TL;DR: In this article, a breve descripcion of la Cromodinamica cuantica de campos is presented, along with propiedades fundamentales de this teoria.
Abstract: En este articulo se presenta una breve descripcion de la Cromodinamica Cuantica. Se discuten las propiedades fundamentales de esta teoria cuantica de campos y se muestran los test experimentales mas importantes que la han establecido como la teoria fundamental de las interacciones fuertes.
1 citations
01 Jan 2011
TL;DR: The existence of tres families of quarks and leptones with propiedades identicas, salvo la masa, plantea muchas preguntas fundamentales que el actual marco teorico es incapaz de contestar.
Abstract: La existencia de tres familias de quarks y leptones con propiedades identicas, salvo la masa, plantea muchas preguntas fundamentales que el actual marco teorico es incapaz de contestar. La Teoria Estandar describe correctamente los fenomenos observados, con gran precision, pero no proporciona una comprension satisfactoria de la dinamica de sabor. El descubrimiento del boson de Higgs o de un mecanismo alternativo de rotura de la simetria electrodebil, y el estudio de violaciones de la simetria CP, pueden aportar indicios importantes sobre nueva fisica asociada con el sabor de los fermiones.