10 research outputs found
Spectroscopy of B_c Mesons in the Relativized Quark Model
We calculate the spectrum of the charm-beauty mesons using the relativized
quark model. Using the wavefunctions from this model we compute the radiative
widths of excited c\bar{b} states. The hadronic transition rates between
c\bar{b} states are estimated using the Kuang-Yan approach and are combined
with the radiative widths to give estimates of the relative branching ratios.
These results are combined with production rates at the Tevatron and the LHC to
suggest promising signals for excited B_c states. Our results are compared with
other models to gauge the reliability of the predictions and point out
differences.Comment: 15 pages, 1 fig. uses revtex4. References adde
Radiative proton-antiproton annihilation to a lepton pair
The annihilation of proton and antiproton to electron-positron pair,
including radiative corrections due to the emission of virtual and real photons
is considered. The results are generalized to leading and next-to leading
approximations. The relevant distributions are derived and numerical
applications are given in the kinematical range accessible to the PANDA
experiment at the FAIR facility.Comment: 2 figure
Bremsstrahlung and pair production processes at low energies, multi-differential cross section and polarization phenomena
Radiative electron-proton scattering is studied in peripheral kinematics,
where the scattered electron and photon move close to the direction of the
initial electron. Even in the case of unpolarized initial electron the photon
may have a definite polarization. The differential cross sections with
longitudinally or transversal polarized initial electron are calculated. The
same phenomena are considered for the production of an electron-positron pair
by the photon, where the final positron (electron) can be also polarized.
Differential distributions for the case of polarized initial photon are given.
Both cases of unscreened and completely screened atomic targets are considered.Comment: 15 pages, 6 figure
Vector exchanges in production of light meson pairs and elementary atoms
The production of pseudoscalar and scalar mesons pairs and bound states
(positronium or pionium atoms) in high energy collisions at high
energies provided by photon or vector meson exchanges are considered. The
vector exchanges lead to nondecreasing with energy cross section of binary
process with states in the fragmentation
regions of initial particles. The production of light mesons pairs as well as a pairs of positronium and
pionium atoms in peripheral kinematics are discussed. Unlike the photon
exchange the vector meson exchange needs a reggeization, leading to fall with
energy. Nevertheless due to peripheral kinematics out of very forward
production angles the vector meson exchanges dominated. The proposed approach
allows to express the matrix elements of the considered processes through
impact factors, which can be calculated in perturbation models like Chiral
Perturbation Theory (ChPT) or Nambu-Jona-Lasinio (NJL) model or determined from
sub-processes or vector mesons radiative decay widths. We obtain
the cross sections for pionium atom production in collisions of high energy
pions and electrons with protons. The possibility to measure these processes in
experiment are discussed.Comment: 12 pages, 2 figure
Pairs Emission in a Uniform Background Field: an Algebraic Approach
A fully algebraic general approach is developed to treat the pairs emission
and absorption in the presence of some uniform external background field. In
particular, it is shown that the pairs production and annihilation operators,
together with the pairs number operator, do actually fulfill the SU(2)
functional Lie algebra. As an example of application, the celebrated Schwinger
formula is consistently and nicely recovered, within this novel approach, for a
Dirac spinor field in the presence of a constant and homogeneous electric field
in four spacetime dimensions.Comment: 26 pages, no figure