14 research outputs found
Rare Kaon Decays in the -Expansion
We study the unknown coupling constants that appear at order in the
Chiral Perturbation Theory analysis of ,
and decays. To that
end, we compute the chiral realization of the Hamiltonian
in the framework of the -expansion of the low-energy action. The
phenomenological implications are also discussed.Comment: 18 pages, LaTeX, CPT-92/P.279
Search for the decay in the momentum region
We have searched for the decay in the kinematic
region with pion momentum below the peak. One event was
observed, consistent with the background estimate of . This
implies an upper limit on
(90% C.L.), consistent with the recently measured branching ratio of
, obtained using the standard model
spectrum and the kinematic region above the peak. The
same data were used to search for , where is a weakly
interacting neutral particle or system of particles with .Comment: 4 pages, 2 figure
Further search for the decay in the momentum region P < 195 MeV/c
We report the results of a search for the decay
in the kinematic region with momentum MeV/c using the
data collected by the E787 experiment at BNL. No events were observed. When
combined with our previous search in this region, one candidate event with an
expected background of events results in a 90% C.L. upper limit
of on the branching ratio of .
We also report improved limits on the rates of and where are hypothetical, massless, long-lived
neutral particles.Comment: 5 pages, 3 figures, Accepted for publication in Phys. Rev.
Saturation of counterterms by resonances in decays
The decays , and are
reinvestigated within the framework of chiral perturbation theory. The
counterterms induced by strong, electromagnetic and weak interactions are
determined assuming the resonance exchange. The weak deformation model, the
factorization model and the large limit are used to create a weak
Lagrangian. It is found that the results of the first two approaches depend on
the coupling, defined in the effective chiral Lagrangian of the order. The set of parameters used in the extended Nambu and
Jona-Lasinio model can accommodete
decay rate within the factorization approach. The CP violating decay rate is discussed.Comment: 24 pages, LaTe
New hadrons as ultra-high energy cosmic rays
Ultra-high energy cosmic ray (UHECR) protons produced by uniformly
distributed astrophysical sources contradict the energy spectrum measured by
both the AGASA and HiRes experiments, assuming the small scale clustering of
UHECR observed by AGASA is caused by point-like sources. In that case, the
small number of sources leads to a sharp exponential cutoff at the energy
E<10^{20} eV in the UHECR spectrum. New hadrons with mass 1.5-3 GeV can solve
this cutoff problem. For the first time we discuss the production of such
hadrons in proton collisions with infrared/optical photons in astrophysical
sources. This production mechanism, in contrast to proton-proton collisions,
requires the acceleration of protons only to energies E<10^{21} eV. The diffuse
gamma-ray and neutrino fluxes in this model obey all existing experimental
limits. We predict large UHE neutrino fluxes well above the sensitivity of the
next generation of high-energy neutrino experiments. As an example we study
hadrons containing a light bottom squark. These models can be tested by
accelerator experiments, UHECR observatories and neutrino telescopes.Comment: 17 pages, revtex style; v2: shortened, as to appear in PR
Rare Decays
The rare decays of the meson have had a long tradition as a laboratory
for testing the symmetry properties of the weak interactions, and the manner in
which these symmetries are broken by higher order effects. Present--day
interest is focussed on decays that are suppressed by --symmetry or GIM
symmetry. Such decays, in the standard theory, are sensitive to effects of the
virtual top quark, and could also reveal new interactions transcending the
standard model. In addition, the radiative decays of the meson have become
a useful testing--ground for effective Lagrangians describing the low energy
interactions of pions, kaons and photons.Comment: Invited Talk at the Third Workshop on High Energy Particle Physics
(WHEPP 3) Madras, 1994, LaTex, 14 pages, 3 figures available upon reques
Recommended from our members
Prospects for observing K/sup +/. -->. pi. /sup +/nu anti nu
We report on the progress of experiment 787 at Brookhaven National Laboratory designed to study K/sup +/ ..-->.. ..pi../sup +/ + '...', where '...' is a one or more feebly interacting neutrals. The experiment will have an initial sensitivity of 2 x 10/sup -10/ for two or more particles (e.g., K/sup +/ ..-->.. ..pi../sup +/nu anti nu), and 4 x 10/sup -11/ for one particle (e.g., K/sup +/ ..-->.. ..pi../sup +/ + axion). The experiment can also study such reactions as K/sup +/ ..-->.. ..pi../sup +/..gamma gamma.., K/sup +/ ..-->.. ..pi../sup +/..mu../sup + -/e/sup - +/, K/sup +/ ..-->.. ..mu../sup +/nu..gamma.., ..pi../sup 0/ ..-->.. nu anti nu, and ..pi../sup 0/ ..-->.. e/sup +/e/sup -/. 6 refs., 4 figs
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A high resolution detector for H{sup 0} {yields} {gamma}{gamma}
SSC detectors represent a challenging departure, both in size and precision, from currently operating detectors. In this note we enumerate some of the benefits of using high magnetic fields both to simplify the detector and improve its resolution and sensitivity. We have chosen an arrangement optimized to search for the reaction H{sup 0} {yields} {gamma}{gamma}. The arrangement also has the excellent momentum resolution for muons and electrons considered critical for the discovery of such processes as H{sup 0} {yields} Z{sup 0}Z{sup 0} {yields} {ell}{sup +}{ell}{sup {minus}}{ell}{sup +}{ell}{sup {minus}}, H{sup 0} {yields} Z{sup 0}Z{sup 0} {yields} {ell}{sup +}{ell}{sup {minus}}{ell}{sup +}{ell}{sup {minus}}, new and narrow vector bosons, and bound states of extra generational quarks. This detection scheme represents an improvement in the H{sup 0} {yields} {gamma}{gamma} mass resolution of at least a factor of 7 beyond the best currently proposed detectors. In addition, we have a significantly improved rejection of common H{sup 0} {yields} {gamma}{gamma} backgrounds. As indeed most experiments do not exceed their initial projections, this extra factor could insure the unambiguous discovery of this decay should it indeed occur. As no reasonably realistic detector can achieve excellent detection for all physics signatures we chose to give tip on excellent hadron calorimetry. For Higgs masses between 80 and 150 GeV/c{sup 2} the Higgs decay into two photons is an excellent signature. To date, all attempts to search for this decay mode have centered on the use of electromagnetic calorimetry. We are proposing a different approach. We will convert the two photons close to the production point and measure the momenta of the electron pairs