2,127 research outputs found
Palatini-Born-Infeld Gravity, Bouncing Universe, and Black Hole Formation
We consider the Palatini formalism of the Born-Infeld gravity. In the
Palatini formalism, the propagating mode is only graviton, whose situation is
different from that in the metric formalism. We discuss about the FRW cosmology
by using an effective potential. Especially we consider the condition that the
bouncing could occur. We also give some speculations about the black hole
formationComment: LaTeX 10 pages, title is changed, the differences from the previous
works are clarified, version to appear in Physics Letters
The sigma-Meson Production in Excited Upsilon Decay Processes
We analyze the pipi production amplitudes in the excited Upsilon decay
processes, Upsilon (2S) to Upsilon (1S)pi^+pi^-, Upsilon (3S) to Upsilon
(1S)pi^+pi^- and Upsilon (3S) to Upsilon (2S)pi^+pi^-, and the pipi and KKbar
production amplitudes in the charmonium decay processes, psi (2S) to Jpsi
pi^+pi^- and Jpsi to phi pi^+pi^-, phi K^+K^-, including the possible effect of
light sigma production. The amplitudes are parametrized by the sum of
Breit-Wigner amplitudes for the sigma and the other relevant particles and of
the direct 2pi-production amplitude, following the VMW method. All the pipi
(and KKbar mass spectra are reproduced well with the obtained values of
sigma-parameters, m_sigma =526(+48,-37)MeV and Gamma_sigma =301(+145,-100)MeV,
which is almost consistent with the values in our previous phase shift
analyses.Comment: proc. of "Hadron '01," Protvino, Russia, Aug, 2001. 5 pages, uses
ptptex.st
The Ds(2317) and Ds(2463) Mesons as Scalar and Axial-Vector Chiralons in the Covariant Level-Classification Scheme
The new narrow mesons observed recently in the final states Ds+ pi0 and Ds*+
pi0 are pointed out to be naturally assigned as the ground-state scalar and
axial-vector chiralons in the c sbar system, which would newly appear in the
covariant hadron-classification scheme proposed a few years ago.Comment: 8 pages, 1 figure, uses ptptex.st
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