Study of tau- --> V P- nu(tau) in the framework of resonance chiral theory

In this paper we study two kinds of tau decays: (a) tau- --> (rho pi-,omega pi-, phi pi-, K*0 K-) nu(tau), which belong to Delta S=0 processes and (b) Delta S = 1 processes, like tau- --> (rho K-, omega K-, phi K-, \bar{K*0} pi-) nu(tau), in the framework of resonance chiral theory. We fit the tau- --> omega pi- nu(tau) spectral function and the invariant mass distribution of omega K in the process of tau- --> omega K- nu(tau) to get the values of unknown resonance couplings. Then we make a prediction for branching ratios of all channels.Comment: Published version; References added. 20 pages, 3 figures, 2 table

τ−→π−γντ\tau^-\to\pi^-\gamma\nu_\tau as a source of background on the Lepton Flavour Violating decay τ−→μ−γ\tau^-\to\mu^-\gamma

We calculate the decay of $\tau^-\to\pi^-\gamma\nu_\tau$ in the framework of Resonance Chiral Theory ($R\chi T$). By demanding the high energy constraints from QCD on the related form factors, we could predict the various physical observables of $\tau^-\to\pi^-\gamma\nu_\tau$ without any free parameter. Our results show that for a realistic cut on the photon energy (around $100$ MeV) this mode gives a branching ratio of roughly $0.1$ that should have already been detected at the heavy-flavour factories. Another interesting subject we have studied based on our calculation of the decay $\tau^-\to\pi^-\gamma\nu_\tau$ is the experimental background estimation of the lepton flavour violation process $\tau^- \to \mu^- \gamma$. We point out that although the description of radiation that PHOTOS provides -which has been used by BaBar and Belle collaborations to estimate this source of background- is in excellent agreement with the theoretical expectations in the low energy region in $\tau^-\to\pi^-\gamma\nu_\tau$ decay, this is not the case in the high energy region, precisely where it is easier that this decay mimics the process $\tau^-\to\mu^-\gamma$.Comment: 6 pages, 7 figures. Contribution to the Proceedings of the TAU10 Conference held in Manchester, 13-17 September 2010. To be published in Nucl. Phys. Proc. Supp

Analysis of the scalar, axialvector, vector, tensor doubly charmed tetraquark states with QCD sum rules

In this article, we construct the axialvector-diquark-axialvector-antidiquark type currents to interpolate the scalar, axialvector, vector, tensor doubly charmed tetraquark states, and study them with QCD sum rules systematically by carrying out the operator product expansion up to the vacuum condensates of dimension 10 in a consistent way, the predicted masses can be confronted to the experimental data in the future. We can search for those doubly charmed tetraquark states in the Okubo-Zweig-Iizuka super-allowed strong decays to the charmed meson pairs.Comment: 23 pages, 29 figures. arXiv admin note: substantial text overlap with arXiv:1708.0454