scholarly journals Three-loop massive form factors: complete light-fermion corrections for the vector current

2018 ◽  
Vol 2018 (3) ◽  
Author(s):  
Roman N. Lee ◽  
Alexander V. Smirnov ◽  
Vladimir A. Smirnov ◽  
Matthias Steinhauser
Keyword(s):  
Form Factors ◽  
Vector Current ◽  
Light Fermion

scholarly journals Current Algebra and Form Factors of the Axial-Vector Current

1967 ◽  
Vol 37 (4) ◽  
pp. 716-726 ◽  
Author(s):  
Akira Sato ◽  
Yoshimatsu Yokoo ◽  
Junji Takahashi
Keyword(s):  
Current Algebra ◽  
Axial Vector ◽  
Form Factors ◽  
Vector Current ◽  
Axial Vector Current

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 πe3Form Factorf-Near the Mass Shell

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
M. I. Krivoruchenko
Keyword(s):  
Form Factor ◽  
Mass Shell ◽  
Numerical Estimate ◽  
Mass Difference ◽  
Form Factors ◽  
Vector Current ◽  
Gauge Dependence ◽  
A Value ◽  
Model Independent ◽  
The Difference

The generalized Ward-Takahashi identity (gWTI) in the pion sector for broken isotopic symmetry is derived and used for the model-independent calculation of the longitudinal form factorf-of theπe3vector vertex. The on-shellf-is found to be proportional to the mass difference of the pions and the difference between the vector isospinT=1and scalar isospinT=2pion radii. A numerical estimate of the form factor yields a value two times higher than the previous estimate from the quark model. Off-shell form factors are known to be ambiguous because of the gauge dependence and the freedom in the parameterization of the fields. The near-mass-shellf-appears to be an exception, allowing for experimental verification of the consequences of the gWTI. We calculate the near-mass-shellf-using the gWTI and dispersion techniques. The results are discussed in the context of the conservation of vector current (CVC) hypothesis.

Kl4 Decays

2001 ◽  
Vol 16 (supp01a) ◽  
pp. 172-174
Author(s):  
Bing An Li
Keyword(s):  
Chiral Limit ◽  
Axial Vector ◽  
Form Factors ◽  
Vector Current ◽  
Decay Rates ◽  
Adjustable Parameter ◽  
Axial Vector Current ◽  
Effective Theory ◽  
Decay Modes ◽  
Large N

An effective theory of large NC QCD of mesons has been used to study six Kl4 decay modes. PCAC is satisfied. A relationship between three form factors of axial-vector current has been found. ρ → ππ plays important role. the decay rates are calculated in the chiral limit. There is no adjustable parameter.

THE STRUCTURE OF 6Li AND ITS COULOMB FORM FACTORS

1971 ◽  
Vol 32 (C5) ◽  
pp. C5b-269-C5b-270
Author(s):  
Kuniharu Kubodera
Keyword(s):  
Form Factors
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