Showing papers by "Antonio Pich published in 2005"
TL;DR: In this article, the OPAL Collaboration was used to determine the moments of the invariant mass distribution of the hadronic $\ensuremath{tau}$ decays into strange particles by the ODE Collaboration.
Abstract: Recent experimental results on hadronic $\ensuremath{\tau}$ decays into strange particles by the OPAL Collaboration are employed to determine ${V}_{us}$ and ${m}_{s}$ from moments of the invariant mass distribution. Our results are ${V}_{us}=0.2208\ifmmode\pm\else\textpm\fi{}0.0034$ and ${m}_{s}(2\text{ }\text{ }\mathrm{G}\mathrm{e}\mathrm{V})=81\ifmmode\pm\else\textpm\fi{}22\text{ }\text{ }\mathrm{M}\mathrm{e}\mathrm{V}$. The error on ${V}_{us}$ is dominated by experiment and should be improvable in the future. Nevertheless, already now our result is competitive with the standard extraction of ${V}_{us}$ from ${K}_{e3}$ decays, and it is compatible with unitarity.
148 citations
TL;DR: In this article, a meromorphic approximation to the Green function on QCD was matched by imposing the correct large-momentum falloff, both off-shell and on the relevant hadron mass shells, in order to determine a number of chiral low-energy constants of O(p(6), in particular the ones governing SU(3) breaking in the K-l3 vector form factor at zero momentum transfer.
Abstract: Using the 1=/N-C expansion scheme and truncating the hadronic spectrum to the lowest-lying resonances, we match a meromorphic approximation to the Green function onto QCD by imposing the correct large-momentum falloff, both off- shell and on the relevant hadron mass shells. In this way we determine a number of chiral low-energy constants of O(p(6)), in particular the ones governing SU(3) breaking in the K-l3 vector form factor at zero momentum transfer. The main result of our matching procedure is that the known loop contributions largely dominate the corrections of O(p(6)) to f(+)(0). We discuss the implications of our final value f(+)(K0 pi-) (0) = 0.984 +/- 0.012 for the extraction of V-us from K-l3 decays.
134 citations
TL;DR: In this paper, a meromorphic approximation to the Green function on QCD was matched by imposing the correct large-momentum falloff, both off-shell and on the relevant hadron mass shells.
Abstract: Using the 1/N_C expansion scheme and truncating the hadronic spectrum to the lowest-lying resonances, we match a meromorphic approximation to the Green function onto QCD by imposing the correct large-momentum falloff, both off-shell and on the relevant hadron mass shells. In this way we determine a number of chiral low-energy constants of O(p^6), in particular the ones governing SU(3) breaking in the K_{l3} vector form factor at zero momentum transfer. The main result of our matching procedure is that the known loop contributions largely dominate the corrections of O(p^6) to f_{+}(0). We discuss the implications of our final value f_{+}^{K^0 \pi^-}(0)=0.984 \pm 0.012 for the extraction of V_{us} from K_{l3} decays.
116 citations
TL;DR: In this article, the quark mixing factor Vus from hyperon semileptonic decays is analyzed and the discrepancies between the results obtained in two previous studies are clarified.
Abstract: We analyze the numerical determination of the quark mixing factor Vus from hyperon semileptonic decays. The discrepancies between the results obtained in two previous studies are clarified. Our fits indicate sizeable SU(3) breaking corrections, which unfortunately can only be fully determined from the data at the first order. The lack of a reliable theoretical calculation of second-order symmetry breaking effects translates into a large systematic uncertainty, which has not been taken into account previously. Our final result, |Vus| = 0.226±0.005, is not competitive with the existing determinations from Kl3, Kl2 and τ decays.
63 citations
01 Jul 2005
TL;DR: In this article, the authors used the moments of the invariant mass distribution of the hadronic τ decays invariant distribution to determine the strange quark mass m s and m s (2 GeV ) = 81 ± 22 ǫ MeV.
Abstract: We review recent work to determine the strange quark mass m s as well as the proposal to determine | V u s | using hadronic τ decay data. The recent update of the strange spectral function by OPAL and their moments of the invariant mass distribution are employed. Our results are | V u s | = 0.2208 ± 0.0034 and m s ( 2 GeV ) = 81 ± 22 MeV . Our result is already competitive to the standard extraction of | V u s | from K e 3 decays and to the new proposals to determine it. The error on | V u s | is dominated by experiment and will be eventually much improved by the B-factories hadronic τ data. Ultimately, a simultaneous fit to both m s and | V u s | to a set of moments of the hadronic τ decays invariant mass distribution will provide one of the most accurate determinations of these Standard Model parameters.
11 citations
Posted Content•
TL;DR: The 32nd International Conference on High-energy Physics (ICHP) was held in China as mentioned in this paper, with a focus on high-energy physics, and was held between 16-22 de Agosto de 2004.
Abstract: 4 paginas, 1 figura.-- Comunicacion presentada en el 32nd International Conference on High-energy Physics celebrado del 16 al 22 de Agosto de 2004 en Beijing (China).-- arXiv:hep-ph/0410215v1
8 citations
TL;DR: The basic ideas and methods of chiral perturbation theory are briefly reviewed in this article, and the recent attempts to build an effective Lagrangian in the resonance region and summarize the known large-NC constraints on the low-energy chiral couplings.
Abstract: The basic ideas and methods of chiral perturbation theory are briefly reviewed. I discuss the recent attempts to build an effective Lagrangian in the resonance region and summarize the known large–NC constraints on the low-energy chiral couplings.
6 citations
TL;DR: In this article, the quark mixing factor V(us) from hyperon semileptonic decays was analyzed and the discrepancy between the results obtained in two previous studies was clarified.
Abstract: We analyze the numerical determination of the quark mixing factor V(us) from hyperon semileptonic decays. The discrepancies between the results obtained in two previous studies are clarified. Our fits indicate sizeable SU(3) breaking corrections, which unfortunately can only be fully determined from the data at the first order. The lack of a reliable theoretical calculation of second-order symmetry breaking effects translates into a large systematic uncertainty, which has not been taken into account previously. Our final result, V(us) = 0.226 +/- 0.005, is not competitive with the existing determinations from K(l3), K(l2) and \tau decays.
4 citations
Posted Content•
TL;DR: The work presented in this paper was presented at the XXXX Rencontres de Moriond on Electroweak Interactions and Unified Theories (ENIT) 2005 in La Thuile (Italy).
Abstract: 6 paginas, 1 tabla.-- Trabajo presentado en la XXXX Rencontres de Moriond on Electroweak Interactions and Unified Theories celebrada del 5 al 12 de Marzo de 2005 en La Thuile (Italia).
4 citations