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Long distance chiral corrections in beta meson amplitudes
We discuss the chiral corrections to fB and BB with particular emphasis on determining the portion of the correction that arises from long distance physics. For very small pion and kaon masses all of the usual corrections are truly long distance, while for larger masses the long distance portion decreases. These chiral corrections have been used to extrapolate lattice calculations towards the physical region of lighter masses. We show in particular that the chiral extrapolation is better behaved if only the long distance portion of the correction is used. We also display the long distance portions of the infrared enhanced chiral logarithms that appear in partially quenched chiral perturbation theory
Refining the scalar and tensor contributions in decays
In this article we analyze the contribution from intermediate spin-0 and
spin-2 resonances to the decay by means of a chiral
invariant Lagrangian incorporating these mesons. In particular, we study the
corresponding axial-vector form-factors. The advantage of this procedure with
respect to previous analyses is that it incorporates chiral (and isospin)
invariance and, hence, the partial conservation of the axial-vector current.
This ensures the recovery of the right low-energy limit, described by chiral
perturbation theory, and the transversality of the current in the chiral limit
at all energies. Furthermore, the meson form-factors are further improved by
requiring appropriate QCD high-energy conditions. We end up with a brief
discussion on its implementation in the Tauola Monte Carlo and the prospects
for future analyses of Belle's data.Comment: 32 pages, 13 figures. Extended discussion on the numerical importance
of the tensor and scalar resonances and the parametrization of the scalar
propagator. Version published in JHE
D-meson decay constants and a check of factorization in non-leptonic B-decays
We compute the vector meson decay constants fD*, fDs* from the simulation of
twisted mass QCD on the lattice with Nf = 2 dynamical quarks. When combining
their values with the pseudoscalar D(s)-meson decay constants, we were able (i)
to show that the heavy quark spin symmetry breaking effects with the charm
quark are large, fDs*/fDs = 1.26(3), and (ii) to check the factorization
approximation in a few specific B-meson non-leptonic decay modes. Besides our
main results, fD* = 278 \pm 13 \pm 10 MeV, and fDs* = 311 \pm 9 MeV, other
phenomenologically interesting results of this paper are: fDs*/fD* = 1.16 \pm
0.02 \pm 0.06, fDs*/fD = 1.46 \pm 0.05 \pm 0.06, and fDs/fD* = 0.89 \pm 0.02
\pm 0.03. Finally, we correct the value for B(B0 \rightarrow D+ pi-) quoted by
PDG, and find B(B0 \rightarrow D+ pi-) = (7.8 \pm 1.4) \times 10-7.
Alternatively, by using the ratios discussed in this paper, we obtain B(B0
\rightarrow D+ pi-) = (8.3 \pm 1.0 \pm 0.8)\times10-7.Comment: 16 pages, 4 eps figure
Weinberg like sum rules revisited
The generalized Weinberg sum rules containing the difference of isovector
vector and axial-vector spectral functions saturated by both finite and
infinite number of narrow resonances are considered. We summarize the status of
these sum rules and analyze their overall agreement with phenomenological
Lagrangians, low-energy relations, parity doubling, hadron string models, and
experimental data.Comment: 31 pages, noticed misprints are corrected, references are added, and
other minor corrections are mad
Goldstone inflation
Identifying the inflaton with a pseudo-Goldstone boson explains the flatness of its potential. Successful Goldstone Inflation should also be robust against UV corrections, such as from quantum gravity: in the language of the effective field theory this implies that all scales are sub-Planckian. In this paper we present scenarios which realise both requirements by examining the structure of Goldstone potentials arising from Coleman-Weinberg contributions. We focus on single-field models, for which we notice that both bosonic and fermionic contributions are required and that spinorial fermion representations can generate the right potential shape. We then evaluate the constraints on non-Gaussianity from higher-derivative interactions, finding that axiomatic constraints on Goldstone boson scattering prevail over the current CMB measurements. The fit to CMB data can be connected to the UV completions for Goldstone Inflation, finding relations in the spectrum of new resonances. Finally, we show how hybrid inflation can be realised in the same context, where both the inflaton and the waterfall fields share a common origin as Goldstones