14 research outputs found
Observable Neutron-Antineutron Oscillations in Seesaw Models of Neutrino Mass
We show that in a large class of supersymmetric models with spontaneously
broken B-L symmetry, neutron--antineutron oscillations occur at an observable
level even though the scale of B-L breaking is very high, v_{B-L} ~ 2 x 10^{16}
GeV, as suggested by gauge coupling unification and neutrino masses. We
illustrate this phenomenon in the context of a recently proposed class of
seesaw models that solves the strong CP problem and the SUSY phase problem
using parity symmetry. We obtain an upper limit on N-\bar{N} oscillation time
in these models, \tau_{N-\bar{N}} < 10^{9} -10^{10} sec. This suggests that a
modest improvement in the current limit on \tau_{N-\bar{N}} of 0.86 x 10^8 sec
will either lead to the discovery of N-\bar{N} oscillations, or will
considerably restrict the allowed parameter space of an interesting class of
neutrino mass models.Comment: 11 pages RevTeX, 1 figur
Master Formula Approach to Chiral Symmetry Breaking: Pi-Pi scattering
The master formula approach to chiral symmetry breaking is used to analyze
the phase shifts for scattering in the elastic region. The results are
in excellent agreement with the data for the phase shifts up to the K-K bar
threshold. Our analysis shows that the pi-pi data near threshold in the scalar
channel favors a large quark condensate in the vacuum, i.e. \sim
-(240 MeV)^3.Comment: 17 pages, LaTeX, 1 postscript file of 12 figures in addition.
Equation 2 is changed, the rest is the sam
Role of a_1(1260) resonance in multipion decays of light vector mesons
The contribution of the a_1(1260) meson to the amplitudes of the decays
rho(770) to 4 pi, omega(782) to 5 pi, and phi(1020) to 5 pi is analyzed in the
chiral model of pseudoscalar, vector, and axial vector mesons based on the
generalized hidden local symmetry added with the anomalous terms. The analysis
shows that inclusion of a_1 meson in the intermediate states results in
enhancement of the branching ratios of the above decays by the factor ranging
from 1.3 to 1.9 depending on the mass of a_1 meson ranging from 1.23 GeV to
m_{a_1}=m_rho sqrt{2}=1.09 GeV, the greater factor standing in case of lower
mass of the a_1.Comment: 14 pages, 5 figure
Many pion decays of rho(770) and omega(782) mesons in chiral theory
The decays rho(770) to 4 pi and omega(782) to 5pi are considered in detail in
the approach based on the Weinberg Lagrangian obtained upon the nonlinear
realization of chiral symmetry, added with the term induced by the anomalous
Lagrangian of Wess and Zumino. The partial widths and excitation curves of the
decays rho^0 to 2 pi^+ 2 pi^-, pi^+ pi^- 2 pi^0, rho^{+-} to 2 pi^{+-} pi^{-+}
pi^0, rho^(+-} to pi^(+-} 3 pi^0 are evaluated for e^+e^- annihilation,
photoproduction and tau lepton decays. The results of calculations are compared
with the recent CMD-2 data on the decay rho^0 to 2 pi^+ 2 pi^- observed in
e^+e^- annihilation. The omega to 5 pi decay widths and excitation curves in
e^+e^- annihilation are obtained. The angular distributions for various
combinations of the final pions in the decays rho to 4 pi and omega to 5 pi are
written. The perspectives of the experimental study of the above decays in
e^+e^- annihilation, tau lepton decays and photoproduction are discussed.Comment: Revtex, 32 pages including 11 ps figures. Replaced to fit the version
published in Phys. Rev. D. Material rearranged, clarifying remarks and
references added, typos fixe
The decays omega(782), phi(1020) to 5 pi in the hidden local symmetry approach
The decays omega -> 2pi^+ 2pi^- pi^0 and omega -> pi^+ pi^- 3pi^0 are
reconsidered in the hidden local symmetry approach (HLS) added with the
anomalous terms. The decay amplitudes are analyzed in detail, paying the
special attention to the Adler condition of vanishing the whole amplitude at
vanishing momentum of any final pion. Combining the Okubo-Zweig-Iizuka (OZI)
rule applied to the five pion final state, with the Adler condition, we
calculate also the phi -> 2pi^+ 2pi^-pi^0 and phi -> pi^+ pi^- 3pi^0 decay
amplitudes. The partial widths of the above decays are evaluated, and the
excitation curves in e^+e^- annihilation are obtained, assuming reasonable
particular relations among the parameters characterizing the anomalous terms of
the HLS Lagrangian. The evaluated branching ratios B(phi -> pi^+ pi^-
3pi^0)~2x10^{-7} and B(phi -> 2pi^+ 2pi^- pi^0)~7x10^{-7} are such that with
the luminosity L=500 pb^{-1} attained at DAFNE phi factory, one may already
possess about 1685 events of the decays phi -> 5pi.Comment: 15 pages text, 12 pages of figures. Typos corrected, clarifying
remarks added. Accepted for publication in Phys.Rev.