Related papers: A Parametrization for $K^+\to \pi^+\pi^- e^+\nu$

Recently, the formalism needed to relate the finite-volume spectrum of systems of nondegenerate spinless particles has been derived. In this work we discuss a range of issues that arise when implementing this formalism in practice, provide…

We study the ratios R_{e/mu}^{(P)} = Gamma(P -> e nu [gamma])/Gamma(P -> mu nu [gamma]) (P=pi,K) in Chiral Perturbation Theory to order e^2 p^4. We complement the two-loop effective theory results with a matching calculation of the…

The estimation of rare K decay matrix-elements from Kl3 experimental data is extended beyond LO in Chiral Perturbation Theory. Isospin-breaking effects at NLO (and partially NNLO) in the ChPT expansion, as well as QED radiative corrections…

We properly define off-shell $K\to\pi$ transition amplitudes and use them to extract information for on-shell $K\to\pi\pi$ amplitudes within Chiral Perturbation Theory. At order $p^2$ in the chiral expansion all three parameters of weak…

We present a complete calculation of the K_{l3} decays K^+ --> pi^0 l^+ nu_l and K^0 --> pi^- l^+ nu_l to O(p^4, (m_d-m_u) p^2, e^2 p^2) in chiral perturbation theory with virtual photons and leptons. We introduce the concept of generalized…

The vector form factor f_+(t) of the semileptonic decay D -> K l nu, measured recently with a high accuracy, can be used to determine the strong coupling constant g_{D_s^* D K}. The latter is related to the normalised coupling \hat{g}…

Within Chiral Perturbation Theory (CHPT) we compute the form factors A, V and $\gamma = A/V$ in the $\pi \to \nu l \gamma$ decay to $O(p^6)$. A and $\gamma$ obtain corrections of order 25%.

Based on a dispersive approach, we apply the inverse amplitude method to unitarize one-loop SU(2) and SU(3) Chiral Perturbation Theory. Numerically, we find that this unitarization technique yields the correct complex analytic structure in…

The form factors for the $B-->\pi$ transition are evaluated in the entire momentum transfer range by using the constraints obtained in the framework combining the heavy quark expansion and chiral symmetry for light quarks and the quark…

The decays $K^{+} \rightarrow \pi^{+} e^{+} e^{-}$, $K_{S} \rightarrow \pi^{0} e^{+} e^{-}$ and $K_{L} \rightarrow \pi^{0} e^{+} e^{-}$ are reinvestigated within the framework of chiral perturbation theory. The counterterms induced by…

$K_{\ell4}$ decays offer several reasons of interest: they allow an accurate measurement of $\pi\pi$-scattering lengths; they provide the best source for the determination of some low-energy constants of ChPT; one form factor is directly…

The inverse-amplitude method is applied to the one-loop chiral expansion of the pion, kaon, and $K_{l3}$ form factors. Since these form factors are determined by the same chiral low-energy constants, it is possible to obtain finite…

The form factors of the $K^+ \to \gamma$ transition are studied in the light-front quark model and chiral perturbation theory of $O(p^6)$. The decay spectrum of $K^+ \to e^+ \nu_{e}\gamma$, dominated by the structure dependent contribution,…

This paper describes the calculation of the semileptonic K_l3 decay form factor at order p^6 of chiral perturbation theory which is the next-to-leading order correction to the well-known p^4 result achieved by Gasser and Leutwyler. At order…

We compare the linear meson model and chiral perturbation theory in next to leading order in the quark mass expansion. In particular, we compute the couplings L_4--L_8 of chiral perturbation theory as functions of the parameters of the…

In the presence of photons, the neutral $K_{\ell 4}$ decay, $K^0\to\pi^0\pi^-\ell^+\nu_\ell$, can be parameterized in terms of three vectorial, one anomalous, and one tensorial form factors. We present here analytic expressions of two…

Preliminary values for the K+ -> pi+ mu+ mu- branching ratio and form factor are reported, based on 400 events, a factor of 2 more in total events and 100 times the present world sample of fully reconstructed events. The results are…

The form factor \pi^0\gamma^*\gamma^* is obtained to the next leading order of derivative expansion of the chiral anomaly and the VMD. As a test the form factor has been used to calculate the cross section of ee^+-->\pi^0\gamma. Theory…

We perform a matching of the two loop-chiral perturbation theory representation of the scalar Kpi form factor to a dispersive one. Knowing the value of F_K/F_pi and f_+(0) in the Standard Model (SM) allows to determine two O(p^6) LECs, the…

A phenomenological analysis of $K\to \pi\pi\gamma$ ($K_L\to\pi^+\pi^-\gamma$ and $K^+\to\pi^+\pi^0\gamma$) with the direct emission photon is carried out beyond the leading order in the chiral perturbation theory. We show that the…