183 research outputs found
Radiative transition of negative to positive parity nucleon
We investigate the transition in the
framework of light cone QCD sum rules. In particular, using the most general
form of the interpolating current for the nucleon as well as the distribution
amplitudes of the photon, we calculate two transition form factors responsible
for this channel and use them to evaluate the decay width and branching ratio
of the transition under consideration. The result obtained for the branching
fraction is in a good consistency with the experimental data.Comment: A typo has been correcte
Investigation of the semileptonic transition of the into the orbitally excited charmed tensor meson
The transition form factors of the semileptonic decay channel are calculated
within the framework of the three-point QCD sum rules. The fit functions of the
form factors are then used to estimate the total decay width and branching
ratio of this transition. The order of branching ratio shows that this channel
can be detected at LHCb.Comment: 15 Pages, 4 Figures and 5 Table
Anomalous magnetic moment of the muon in the two Higgs doublet model
We calculate the new physics effects on the anomalous magnetic moment of the
muon in the framework of the two Higgs doublet model. We predict an upper bound
for the lepton flavor violating coupling, which is responsible for the point
like interaction between muon and tau, by using the uncertainty in the
experimental result of the muon anomalous magnetic moment. We show that the
upper bound predicted is more stringent compared to the one which is obtained
by using the experimental result of the muon electric dipole momentComment: 8 Pages, 5 Figure
The strong and vertices
We investigate the strong vertices among , nucleon and meson
as well as , nucleon and meson in QCD. In particular, we
calculate the strong coupling constants and
for different Dirac structures entered the calculations. In the case of
vertex, the result is compared with the only existing prediction
obtained at .Comment: 12 Pages, 3 Figures and 4 Table
Scalar and vector self-energies of heavy baryons in nuclear medium
The in-medium sum rules are employed to calculate the shifts in the mass and
residue as well as the scalar and vector self-energies of the heavy and baryons, with Q being or quark. The maximum shift
in mass due to nuclear matter belongs to the baryon and it is found
to be . In the case of residue, it is
obtained that the residue of baryon is maximally affected by the
nuclear medium with the shift .
The scalar and vector self-energies are found to be , , , , , and , ,
, , and
.Comment: 13 Pages, 11 Figures and 5 Table
On the strong coupling
We study the strong vertices , and in QCD, where
denotes the negative parity state. We use the most general
form of the interpolating currents to calculate the corresponding strong
coupling constants. It is obtained that the coupling associated to
vertex is strongly suppressed compared to those related to two other vertices.
The strong coupling corresponding to is obtained to be roughly half
of that of vertex. We compare the obtained results on and
vertices with the existing predictions of other theoretical studies as
well as those extracted from the experimental data.Comment: 15 Pages, 4 Figures and 3 Table
Strong couplings of negative and positive parity nucleons to the heavy baryons and mesons
The strong coupling form factors related to the strong vertices of the
positive and negative parity nucleons with the heavy
baryons and heavy vector mesons are
calculated using a three-point correlation function. Using the values of the
form factors at we compute the strong coupling constants
among the participating particles.Comment: 12 Pages and 7 Table
Positive and negative parity hyperons in nuclear medium
The effects of nuclear medium on the residue, mass and self energy of the
positive and negative parity , and hyperons are
investigated using the QCD sum rule method. In the calculations, the general
interpolating currents of hyperons with an arbitrary mixing parameter are used.
We compare the results obtained in medium with those of the vacuum and
calculate the shifts in the corresponding parameters. It is found that the
shifts on the residues in nuclear matter are over all positive for both the
positive and negative parity hyperons, except for the positive parity
hyperon that the shift is negative. The shifts on the masses of these baryons
are obtained to be negative. The shifts on the residues and masses of negative
parity states are large compared to those of positive parities. The maximum
shift belongs to the residue of the negative parity hyperon. The
vector self-energies gained by the positive parity baryons are large compared
to the negative parities' vector self-energies. The maximum value of the vector
self-energy belongs to the positive parity hyperon. The numerical
values are compared with the existing predictions in the literature.Comment: 20 Pages, 9 Figures and 7 Table
- …