Tensor form factors of $P\to P,S,V$ and $A$ transitions within the standard and the covariant light-front approaches

Abstract

In this paper, we investigate the tensor form factors of $P\to P,S,V$ and $A$ transitions within the standard light-front (SLF) and the covariant light-front (CLF) quark models (QMs). The self-consistency and Lorentz covariance of CLF QM are analyzed via these quantities, and the effects of zero-mode are discussed. For the $P\to V$ and $A$ transitions, besides the inconsistence between the results extracted via longitudinal and transverse polarization states, which is caused by the residual $\omega$-dependent spurious contributions, we find and analyze a "new" self-consistence problem of the traditional CLF QM, which is caused by the different strategies for dealing deal with the trace term in CLF matrix element. A possible solution to the problems of traditional CLF QM is discussed and confirmed numerically. Finally, the theoretical predictions for the tensor form factors of some $c\to q,s$ and $b\to q,s,c$ ($q=u,d$) induced $P\to P,S,V$ and $A$ transitions are updated within the CLF QM with a self-consistent scheme.

Comments: 34 pages, 9 figures and 7 tables. arXiv admin note: text overlap with arXiv:1908.04677