相关论文: Low Energy Constants from Kl4 Form-Factors

The ratio of electric to magnetic proton form factors G_E/G_M as measured in polarization transfer experiments shows a characteristic linear decrease with increasing momentum transfer Q^2. We present a simple argument how such a decrease…

We calculate the finite volume corrections to meson masses and decay constants in two and three flavour Chiral Perturbation Theory to two-loop order. The analytical results are compared with the existing result for the pion mass in…

The leading one-loop corrections to the gravitational form factors of the delta resonance are calculated in the framework of chiral effective field theory. Various contributions to the energy-momentum tensor and the renormalization of the…

We calculate results for K to pi and K to 0 matrix elements to next-to-leading order in 2+1 flavor partially quenched chiral perturbation theory. Results are presented for both the Delta I=1/2 and 3/2 channels, for chiral operators…

We study the properties of the B-->pi and B-->K transition form factors in partially quenched QCD by using the approach of partially quenched chiral perturbation theory combined with the static heavy quark limit. We show that the form…

We study the decays $K\to\pi\pi$ in one-loop two-flavour Chiral Perturbation Theory. We provide arguments why the calculation of the coefficient of the pionic chiral logarithm $\logm = M^2\log M^2$ is unique and then perform the…

We study the hadronic form factors of $\tau$ lepton decays $\tau \to K \pi(\eta) \nu$. We compute one loop corrections to the form factors using the chiral Lagrangian including vector mesons. The counterterms which subtract the divergence…

It is shown that the low energy coefficients of the next-to-leading order (NLO) chiral perturbation theory needed to determine $\Delta I=1/2$, $K\to\pi\pi$ decay amplitudes can be fixed by calculating $K\pi\to\pi$ amplitudes on lattice.…

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…

I consider some selected topics in chiral perturbation theory (CHPT) as probed at colliders such as DA$\Phi$NE. Emphasis is put on processes involving pions in the isospin zero S-wave which require multi-loop calculations. These include the…

We present technical details of the evaluation of the elastic pi-pi scattering amplitude to two loops in chiral perturbation theory. In particular, we elaborate on the renormalization procedure at the two-loop order and on the evaluation of…

Using recent precise hadronic tau-decay data on the V-A spectral function and general properties of QCD such as analyticity, the operator product expansion and chiral perturbation theory, we get accurate values for the QCD chiral order…

We present a calculation of the Vector Form Factor at the next-to-leading order in the 1/N_C expansion, within the framework of Resonance Chiral Theory. The calculation is performed in the chiral limit, and with two dynamical quark…

We present the ingredients necessary for the determination of physical K->pi pi decay amplitudes for Delta I=3/2 transitions, from lattice simulations at unphysical kinematics and the use of chiral perturbation theory at next-to-leading…

The three complex form factors entering the $\Delta\to N\gamma^\ast$ vertex are calculated to ${\cal O}(\epsilon^3)$ in the framework of a chiral effective theory with explicit $\Delta$(1232) degrees of freedom. Furthermore, the role of…

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…

The CP conserving amplitudes for the decays $K\to3\pi$ are calculated in Chiral Perturbation Theory at the next-to-leading order. We present the expressions in a compact form with single parameter functions only. These expressions are then…

We use both old and new theoretical developments in QCD dispersion relation constraints on the scalar form factor in the decay K --> \pi l \nu_l to obtain constraints on the strange quark mass. The perturbative QCD side of the calculation…

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…

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…