相关论文: Chiral Extrapolation of the Strangeness Changing K…

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…

Using partially twisted boundary conditions we compute the K->pi semi-leptonic form factors in the range of momentum transfers 0 <~ q^2 <= q^2_{max}=(mK-mpi)^2 in lattice QCD with N_f=2+1 dynamical flavours. In this way we are able to…

We calculate the form factors of the $K \to \pi l \nu$ semileptonic decays in three-flavor lattice QCD, and study their chiral behavior as a function of the momentum transfer and the Nambu-Goldstone boson masses. Chiral symmetry is exactly…

We derive and calculate unitarity bounds on the slope and curvature of the strangeness-changing scalar form factor at zero momentum transfer, using low-energy constraints and Watson final state interaction theorem. The results indicate that…

We investigate the scalar K pi form factor at low energies by the method of unitarity bounds adapted so as to include information on the phase and modulus along the elastic region of the unitarity cut. Using at input the values of the form…

We calculate the two form-factors for the four Kaon to pion transitions via a vector current to order $p^6$ in Chiral Perturbation Theory to first order in isospin breaking via the quark masses. In addition we derive relations between these…

We obtain stringent bounds in the < r^2 >_S^{K pi}-c plane where these are the scalar radius and the curvature parameters of the scalar pi K form factor respectively using analyticity and dispersion relation constraints, the knowledge of…

We use one-loop $\SU(2)_L\times \SU(2)_R$ chiral perturbation theory ($\SU(2)$ ChPT) to study the behaviour of the form-factors for semileptonic $K\to\pi$ decays with the pion mass at $q^2=0$ and at $q^2_{\textrm{max}}=(m_K-m_\pi)^2$, where…

Employing results from a recent determination of the scalar KPi form factor F_0^KPi within a coupled channel dispersion relation analysis \cite{JOP01}, in this work we calculate the slope and curvature of F_0^KPi(t) at zero momentum…

We derive expressions for strangeness-changing scalar form factors, which incorporate known theoretical constraints both at low and high energies. Their leading behaviour in the limit of a large number of colours is calculated from the…

Several lattice collaborations performing simulations with 2+1 light dynamical quarks have experienced difficulties in fitting their data with standard Nf=3 chiral expansions at next-to-leading order, yielding low values of the quark…

An accurate low-energy dispersive parametrization of the scalar Kpi form factor was constructed some time ago in terms of a single parameter guided by the Callan-Treiman low-energy theorem. A similar twice subtracted dispersive…

The extrapolation of nucleon magnetic form factors calculated within lattice QCD is investigated within a framework based upon heavy baryon chiral effective-field theory. All one-loop graphs are considered at arbitrary momentum transfer and…

We calculate the vector and scalar form factors of the pion to two loops in Chiral Perturbation Theory. We estimate the unknown O(p^6) constants using resonance exchange. We make a careful comparison to the available data and determine two…

We use chiral perturbation theory to study the extrapolations necessary to make physical predictions from lattice QCD data for the electromagnetic form factors of pseudoscalar mesons. We focus on the quark mass, momentum, lattice spacing,…

We calculate the one-loop contributions to the difference \Delta_{\pi K} between the isoscalar on-shell pion-kaon scattering amplitude at the Cheng-Dashen point and the scalar form factor \Gamma_K (2M_\pi^2) in the framework of three flavor…

We calculate the $O(p^6)$ corrections to the anomalous form factors appearing in $\pi^+$, $K^+ \to e^+ \nu \gamma,\ \mu^+\nu\gamma$ and $K_{l4}$ decays in Chiral Perturbation Theory. The relevant dimension $6$ terms of the lagrangian are…

We calculate all of the form factors for the one-photon, $K_L \rightarrow \pi^+ \pi^- \gamma^* \rightarrow \pi^+ \pi^- e^+e^-$ contribution to the $K_L \rightarrow \pi^+ \pi^- e^+e^-$ decay amplitude at leading order in chiral perturbation…

A self-consistent analysis of K->2pi and K->3pi decays within a unique framework of chiral dynamics applied to the QCD-corrected weak nonleptonic quark lagrangian has been performed. The results on K->2pi amplitudes at O(p^6), including the…

The introduction of partially twisted boundary conditions allows weak and electromagnetic form factors to be evaluated at specified values of the hadronic momenta (and hence momentum transfers) in lattice simulations. We present and…