相关论文: Stringent constraints on the scalar K pi form fact…
We consider the vector and scalar form factors of the charm-changing current responsible for the semileptonic decay D\rightarrow \pi l \nu. Using as input dispersion relations and unitarity for the moments of suitable heavy-light…
A method of deriving bounds on the weak meson form factors, based on perturbative QCD, analyticity and unitarity, is generalized in order to fully exploit heavy quark spin symmetry in the ground state $(L=0)$ doublet of pseudoscalar $(B)$…
Recent experimental data for the differential decay distribution of the decay $\tau^-\to\nu_\tau K_S\pi^-$ by the Belle collaboration are described by a theoretical model which is composed of the contributing vector and scalar form factors…
We investigate the pion scalar form factor in the Meiman-Okubo framework, implementing the phase below the inelastic $K\bar K$ threshold, where it is known from the $\pi\pi$ scalar isoscalar phase shift $\delta_0^0$ by Watson theorem.…
The S and P wave $\pi \pi$ phase shifts are recalculated in terms of two phenomenological parameters using the one loop CPTh and the elastic unitarity condition. Using these phase shifts, the vector and scalar form factors are calculated…
Pion-kaon ($\pi K$) pairs occur frequently as final states in heavy-particle decays. A consistent treatment of $\pi K$ scattering and production amplitudes over a wide energy range is therefore mandatory for multiple applications: in…
Bounds on the expansion coefficients of the strangeness changing $K\pi$ form factors were derived recently from analyticity and unitarity, using as input suitable correlation functions calculated by perturbative QCD in the Euclidian region.…
The $\eta \to 3\pi$ decays are a valuable source of information on low energy QCD. Yet they were not used for an extraction of the three flavor chiral symmetry breaking order parameters until now. We use a Bayesian approach in the framework…
The energy and decay width of the pi-K atom are evaluated in the framework of the quasipotential-constraint theory approach. The main electromagnetic and isospin symmetry breaking corrections to the lowest-order formulas for the energy…
We study the constraints arising on the expansion parameters c and d of the Pion electromagnetic form factor from the inclusion of pure space-like data and the phase of time-like data along with one space-like datum, using as input the…
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…
We discuss an on-shell approach to pion-nucleon physics that is consistent order by order in a $1/f_{\pi}$ expansion with the chiral reduction formula, crossing, and relativistic unitarity. A number of constraints between the on-shell…
We calculate the threshold singularities in one-dimensional models using the universal low-energy formfactors obtained in the framework of the non-linear Luttinger liquid model. We find the reason why the simplified picture of the impurity…
Assuming the length of the $3\pi$ cut to be finite and approximating the integrated amplitude by a constant, we derive an expression for the $\pi N\bar{N}$ form factor which is very close to that given by a simple pole. The specific…
This work studies the $\phi \to 3\pi$ decay and the $\phi \to \pi^0 \gamma^\ast$ transition form factor, utilizing the Khuri-Treiman formalism to account for analyticity, crossing, and unitarity. Using once-subtracted dispersion relations,…
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 chiral low energy theorems and elastic unitarity assumption, the $\tau\to\pi K \nu $ decay is investigated. The vector and scalar $\pi K$ form factors are calculated. It is found that the $\pi K$ spectrum is dominated by the $K^*$…
Clean tests of a small admixture of right-handed quark currents directly coupled to the standard W are still lacking. We show that such non-standard couplings can be significantly constrained measuring the value of the scalar Kpi form…
The slope and curvature parameters of the $K\pi$ vector form factor, $F_+^{K\pi}$, are fitted to the data on $\tauKpi$ and $K_{l3}$ decays yielding $\lambda_+'=(25.49 \pm 0.31) \times 10^{-3}$ and $\lambda_+"= (12.22 \pm 0.14) \times…
Low lying scalar resonances emerge as a necessary part to adjust chiral perturbation theory to experimental data once unitarity constraint is taken into consideration. I review recent progress made in this direction in a model independent…