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# Search results

63 records were found.

## How far can you go ? Surprises and pitfalls in three-flavour chiral extrapolations

Comment: 7 pages, 4 figures, Presented at the XXV International Symposium on Lattice Field Theory, July 30 - August 4 2007, Regensburg, Germany

## Connecting B_d and B_s decays through QCD factorisation and flavour symmetries

Comment: Proceedings of the EPS-HEP 2007 Conference, Manchester (UK). 3 pages, 1 figure

## QCD factorisation and flavour symmetries illustrated in B_d,s -> KK decays

Comment: 4 pages, 2 figures. Talk given at the 4th International Workshop on the CKM Unitarity Triangle (CKM2006), 12-16 December 2006, Nagoya, Japan, to appear in the proceedings (KEK Report)

## Low-energy pi-pi and pi-K scatterings revisited in three-flavour resummed chiral perturbation theory

Comment: 35 pages, 3 figures, accepted for publication in Eur. Phys. J. C

## The role of strange sea quarks in chiral extrapolations on the lattice

Comment: 31 pages, 9 figures. A few comments added and typos corrected

## pi-pi and pi-K scatterings in three-flavour resummed chiral perturbation theory

Comment: Proceedings of the EPS-HEP 2007 Conference, Manchester (UK). 3 pages, 1 figure

## Minimal Flavour Violation for Leptoquarks

Scalar leptoquarks, with baryon and lepton number conserving interactions, could have TeV scale masses, and be produced at colliders or contribute to a wide variety of rare decays. Some insight as to the most sensitive search channels would be useful. We assume that the leptoquark-lepton-quark coupling can be constructed from the known mass matrices, and estimate the rates for selected rare processes in three cases: leptoquarks carrying lepton and quark flavour, leptoquarks with quark flavour only, and unflavoured leptoquarks. We find that leptoquark decay to top quarks is an interesting search channel.

## A note on renormalon models for the determination of alpha_s(M_tau)

The tau hadronic width provides a determination of the strong coupling constant alpha_s at low energies, since it can be related to a weighted integral of the Adler function in the complex energy plane. Using Operator Product Expansion, one sees that the sensitivity to alpha_s comes from the perturbative contribution, which can be obtained by integrating the perturbative expansion of the Adler function. Two different prescriptions proposed to perform this integral, called Fixed-Order Perturbation Theory and Contour-Improved Perturbation Theory (FOPT and CIPT), yield different results for the strong coupling constant. Recently, models for the Adler function based on renormalon calculus have been proposed to determine which of the two methods is the most accurate, by comparing the resulting asymptotic series with the true value of the in...

## The K^*_0(800) scalar resonance from Roy-Steiner representations of pi K scattering

We discuss the existence of the light scalar meson K^*_0(800) (also called kappa) in a rigorous way, by showing the presence of a pole in the pi K --> pi K amplitude on the second Riemann sheet. For this purpose, we study the domain of validity of two classes of Roy-Steiner representations in the complex energy plane. We prove that one of them is valid in a region sufficiently broad in the imaginary direction. From this representation, we compute the l=0 partial wave in the complex plane with neither additional approximation nor model dependence, relying only on experimental data. A scalar resonance with strangeness S=1 is found with the following mass and width: E_0 = 658 \pm 13 MeV and Gamma_0 = 557 \pm 24 MeV.

## Renormalization of B-meson distribution amplitudes

Comment: 7 pages, 2 figures. Contribution to the proceedings of the Int. Workshop on Effective Field Theories: from the pion to the upsilon. Feb. 2009. Valencia, Spain