scholarly journals THE ROLE OF $K^*_0(1430)$ IN D → PK AND τ → KPντ DECAYS

1999 ◽  
Vol 14 (26) ◽  
pp. 4161-4175 ◽  
Author(s):  
S. FAJFER ◽  
J. ZUPAN
Keyword(s):  
Experimental Data ◽  
Form Factor ◽  
Matrix Element ◽  
Scalar Meson ◽  
Final State Interaction ◽  
Form Factors ◽  
Decay Rates ◽  
Scalar Form Factor ◽  
Meson Resonance ◽  
Scalar Form

We consider the scalar form factor in the weak current matrix element <PK|jμ|0>, P=π, η, η′. It obtains the contributions from the scalar meson resonance [Formula: see text] and from the scalar projection of the vector meson K*(892) resonance. We analyze decay amplitudes of the Cabibbo suppressed decays D → KP, P=π, η, η′ using the factorization approach. The form factors of the relevant matrix elements are described by assuming the dominance of nearby resonances. The annihilation contribution in these decays arises from the matrix element <PK|jμ|0>. All the required parameters are experimentally known except the scalar meson [Formula: see text] decay constant. We fit the decay amplitudes and we find that final state interaction improves the agreement with the experimental data. Then we extract bounds on scalar form factor parameters and compare them with the experimental data obtained in the analyses of K→πeνe and K→πμνμ. The same scalar form factor is present in the τ → KPντ decay, with P=π, η, η′. Using the obtained bounds we investigate the significance of the scalar meson form factor in the τ→ KPντ, P=π, η, η′ decay rates and spectra. We find that the [Formula: see text] scalar meson dominates in the τ→Kη′ντ decay spectrum.

scholarly journals Tensor form factor for the D → π(K) transitions with Twisted Mass fermions.

2018 ◽  
Vol 175 ◽  
pp. 13022
Author(s):  
Vittorio Lubicz ◽  
Lorenzo Riggio ◽  
Giorgio Salerno ◽  
Silvano Simula ◽  
Cecilia Tarantino
Keyword(s):  
Form Factor ◽  
Matrix Element ◽  
Form Factors ◽  
Vector Current ◽  
Hadronic Matrix Element ◽  
Tensor Form ◽  
Scalar Form ◽  
Mass Collaboration ◽  
Twisted Mass ◽  
Tensor Current

We present a preliminary lattice calculation of the D → π and D → K tensor form factors fT (q2) as a function of the squared 4-momentum transfer q2. ETMC recently computed the vector and scalar form factors f+(q2) and f0(q2) describing D → π(K)lv semileptonic decays analyzing the vector current and the scalar density. The study of the weak tensor current, which is directly related to the tensor form factor, completes the set of hadronic matrix element regulating the transition between these two pseudoscalar mesons within and beyond the Standard Model where a non-zero tensor coupling is possible. Our analysis is based on the gauge configurations produced by the European Twisted Mass Collaboration with Nf = 2 + 1 + 1 flavors of dynamical quarks. We simulated at three different values of the lattice spacing and with pion masses as small as 210 MeV and with the valence heavy quark in the mass range from ≃ 0.7 mc to ≃ 1.2mc. The matrix element of the tensor current are determined for a plethora of kinematical conditions in which parent and child mesons are either moving or at rest. As for the vector and scalar form factors, Lorentz symmetry breaking due to hypercubic effects is clearly observed in the data. We will present preliminary results on the removal of such hypercubic lattice effects.

scholarly journals The $$ \overline{B} $$ → π form factors from QCD and their impact on |Vub|

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Domagoj Leljak ◽  
Blaženka Melić ◽  
Danny van Dyk
Keyword(s):  
Form Factor ◽  
Lattice Qcd ◽  
Sum Rules ◽  
Semileptonic Decay ◽  
Form Factors ◽  
Scalar Form Factor ◽  
Small Momentum Transfer ◽  
Scalar Form ◽  
Sum Rule ◽  
First Time

Abstract We revisit light-cone sum rules with pion distribution amplitudes to determine the full set of local $$ \overline{B} $$ B ¯ → π form factors. To this end, we determine all duality threshold parameters from a Bayesian fit for the first time. Our results, obtained at small momentum transfer q2, are extrapolated to large q2 where they agree with precise lattice QCD results. We find that a modification to the commonly used BCL parametrization is crucial to interpolate the scalar form factor between the two q2 regions. We provide numerical results for the form factor parameters — including their covariance — based on simultaneous fit of all three form factors to both the sum rule and lattice QCD results. Our predictions for the form factors agree well with measurements of the q2 spectrum of the semileptonic decay $$ {\overline{B}}^0\to {\pi}^{+}{\mathrm{\ell}}^{-}{\overline{\nu}}_{\mathrm{\ell}} $$ B ¯ 0 → π + ℓ − ν ¯ ℓ . From the world average of the latter we obtain |Vub| = (3.77 ± 0.15) · 10−3, which is in agreement with the most recent inclusive determination at the 1 σ level.

The contribution of valence quarks in the nucleon GE and GM

2019 ◽  
Vol 34 (27) ◽  
pp. 1950148
Author(s):  
Negin Sattary Nikkhoo ◽  
Mohammad Reza Shojaei
Keyword(s):  
Experimental Data ◽  
Angular Momentum ◽  
Form Factor ◽  
Total Angular Momentum ◽  
Form Factors ◽  
Distribution Functions ◽  
The Other ◽  
Parton Distribution Functions ◽  
Nucleon Electromagnetic Form Factor ◽  
Elastic Form

The goal of this paper is to extract the flavor decomposition of nucleon electromagnetic form factor using the modified Gaussian and extended Regge ansatzes in the GPDs. We consider the CJ15 and JR09 parton distribution functions for both of these ansatzes in calculating the nucleon elastic form factors. Our results are compared with experimental data in the range [Formula: see text] 4-momentum transfers. Also, we calculate the total angular momentum carried by quarks, the gravitational form factors, and the transverse gravitational density for quarks of the nucleon. In the end, our results are compared with the other studies.

scholarly journals NUCLEAR INTERACTIONS: THE CHIRAL PICTURE

2008 ◽  
Vol 23 (27n30) ◽  
pp. 2273-2280 ◽  
Author(s):  
M. R. ROBILOTTA
Keyword(s):  
Form Factor ◽  
Pion Exchange ◽  
Scalar Form Factor ◽  
Scalar Form ◽  
Central Potential ◽  
Nuclear Interactions

Chiral expansions of the two-pion exchange components of both two- and three-nucleon forces are reviewed and a discussion is made of the predicted pattern of hierarchies. The strength of the scalar-isoscalar central potential is found to be too large and to defy expectations from the symmetry. The causes of this effect can be understood by studying the nucleon scalar form factor.

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