Related papers: Calculation of P-Wave Charmonium Decay Rates Using…
In this work, we calculate the amplitudes of the processes $c\bar c({^3P_J}) \rightarrow DD,DD^*, D^*D^* \rightarrow c\bar c({^3P_J})$ in the leading order of the nonrelativistic expansion. The imaginary parts of the amplitudes are…
We construct a relativistic $^3P_0$ wavefunction for scalar mesons within the framework of light-front quark model(LFQM). This scalar wavefunction is used to perform relativistic calculations of absolute widths for the radiative decay…
The decay Delta^+ --> p gamma is studied in the 1/N_c expansion of QCD. The ratio of the helicity amplitudes is determined to be A_{3/2}/A_{1/2} = \sqrt{3} + O(1/N_c^2). Equivalently, the ratio E2/M1 of the multipole amplitudes is predicted…
We investigate the spectrum and decay rates of low lying charmonium states within the framework of the non relativistic quark model by employing a Coulomb like potential from the perturbative one gluon exchange and the linear confining…
We compute the renormalization mismatch displayed in 1--loop approximation by classically equivalent 4-quark operators and coming from different possible definitions of the $\gamma_5$ matrix in dimensional regularization. The result is then…
The masses of $1^{--}$ P-wave charmonium-like and bottomonium-like tetraquark states are calculated in a constituent quark model (CQM) where the Cornell-like potential and Breit-Fermi interaction are employed. All model parameters were…
We calculate the long-distance matrix elements for the decays of the lowest-lying S- and P-wave states of charmonium and bottomonium in quenched lattice QCD, using a nonrelativistic formulation for the heavy quarks. (The short-distance…
Estimating decay parameters in lattice simulations is a computationally demanding problem, requiring several volumes and momenta. We explore an alternative approach, where the transition amplitude can be extracted from the spectral…
Recent results include the measurement of B->D(*)pi+pi-pi-pi0 decays, with rates of ~1.8% observation of a significant omega pi^- substructure that appears to result from the decay of the rho' resonance, whose mass and width we determine as…
The method of QCD light-cone sum rules is used to calculate soft nonfactorizable contributions to the decay amplitude for B -> J/psi K. The result confirms expectations that in color-suppressed decays nonfactorizable corrections can be…
The mass spectra of charmonium are investigated using a Coulomb plus linear (Cornell) potential. Gaussian wave function in position space as well as in momentum space are employed to calculate the expectation value of potential and kinetic…
The decay constants of the low lying S-wave $B_c$ mesons, i.e. $B_c(nS)$ and $B^*_c(nS)$ with $n\leq 3$, are calculated in the nonrelativistic quark model. The running coupling of the strong interaction is taken into account, and the…
Within the QCD factorization approach we compute the amplitudes for annihilation channels of B mesons decays into final states containing two pseudoscalar particles. These decays may be plagued by effects like non-perturbative physics or…
Corrections $\sim \alpha^2 $ to the positronium decay rate, induced by one--loop vacuum polarization diagram, are calculated. Their relative values are $0.4468(3)(\alpha/\pi)^2$ for para- and $0.960(3)(\alpha/\pi)^2$ for orthopositronium.
Dimensional regularization is used to derive the equations of motion of two point masses in harmonic coordinates. At the third post-Newtonian (3PN) approximation, it is found that the dimensionally regularized equations of motion contain a…
Decay constants of $P$-wave mesons are computed in the framework of instantaneous Bethe-Salpeter method (Salpeter method). By analyzing the parity and possible charge conjugation parity, we give the relativistic configurations of wave…
One can analyze the hadronic decay amplitudes for $B\to PP$ decays using flavor SU(3) symmetry in different ways, such as the algebraic and quark diagram approaches. We derive specific relations between these two sets of amplitudes. In the…
QCD string model is employed to calculate the masses and spin splittings of lowest charmonium hybrid states with a magnetic gluon. Relative decay rates into various S- and P-wave D-meson pairs are calculated for these hybrids.
The decays B -> D^{**} pi, where D^{**} is a narrow p-wave charm resonance, are investigated in the context of a generalized factorization hypothesis, including the leading nonfactorizable corrections. The decay rates for these processes…
Radiative decays of the spin 1/2 baryonic resonances R with the decay mode R -> KN in case of small energy release are considered. Pentaquark is an example of such resonance. It is shown that in case of positive resonance parity corrections…