1,771 research outputs found
K-matrix analysis of the (IJ^{PC}=00^{++})-wave in the mass region below 1900 MeV
We present the results of the current analysis of the partial wave
IJ^{PC}=00^{++} based on the available data for meson spectra (pi-pi, K\bar K,
eta-eta, eta-eta', pi-pi-pi-pi). In the framework of the K-matrix approach, the
analytical amplitude has been restored in the mass region 280 MeV< \sqrt s
<1900 MeV. The following scalar-isoscalar states are seen: comparatively narrow
resonances f_0(980), f_0(1300), f_0(1500), f_0(1750) and the broad state
f_0(1200-1600). The positions of the amplitude poles (masses and total widths
of the resonances) are determined as well as pole residues (partial widths to
meson channels pi-pi, K\bar K, eta-eta, eta-eta', pi-pi-pi-pi). The fitted
amplitude gives us the positions of the K-matrix poles (bare states) and the
values of bare-state couplings to meson channels thus allowing the
quark-antiquark nonet classification of bare states. On the basis of the
obtained partial widths to the channels pi-pi, K\bar K, eta-eta, eta-eta', we
estimate the quark/gluonium content of f_0(980), f_0(1300), f_0(1500),
f_0(1750), f_0(1200-1600). For f_0(980), f_0(1300), f_0(1500) and f_0(1750),
their partial widths testify the q\bar q origin of these mesons though being
unable to provide precise evaluation of the possible admixture of the gluonium
component in these resonances. The ratios of the decay coupling constants for
the f_0(1200-1600) support the idea about gluonium nature of this broad state.Comment: 59 pages, 18 figures, epsfig, references are adde
Problem of the Complete Measurement for CP-violating Parameters in Neutral B-meson Decays
Phenomenological CP-violating parameters in decays of neutral B-mesons are
discussed. Special attention is given to the degree of their measurability. We
emphasize important role of the sign of and suggest how it could
be determined experimentally.Comment: 12 pages, no figures; some small errors are corrected, publication
reference is appende
Polarization degrees of freedom in near-threshold photoproduction of omega mesons in the pi^0 gamma decay channel
We study polarization variables in the photoproduction of omega-mesons with
subsequent omega to gamma pi^0 decay. Single and double polarization
observables are calculated as a function of different final-state angles.
Reaction models include pomeron (natural parity) and pi^0 (unnatural parity)
exchange in the t-channel. In addition, the contribution of s-channel
resonances is considered. The sensitivity of the polarization observables to
the reaction dynamics is discussed.Comment: 10 pages, 10 figures, explicit reference to sign of decay asymmetry
adde
Baryon-baryon and baryon-antibaryon interaction amplitudes in the spin--momentum operator expansion method
Partial wave scattering amplitudes in baryon-baryon and baryon-antibaryon
collisions and amplitudes for the production and decay of baryon resonances are
constructed in the framework of the spin-momentum operator expansion method.
The approach is relativistically invariant and it allows us to perform combined
analyses of different reactions imposing analyticity and unitarity directly.
The role of final state interactions (triangle and box diagrams) is discussed.Comment: 23 pages, 10 figure
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