33 research outputs found
CPT and Lorentz violation as signatures for Planck-scale physics
In recent years, the breakdown of spacetime symmetries has been identified as
a promising research field in the context of Planck-scale phenomenology. For
example, various theoretical approaches to the quantum-gravity problem are
known to accommodate minute violations of CPT invariance. This talk covers
various topics within this research area. In particular, some mechanisms for
spacetime-symmetry breaking as well as the Standard-Model Extension (SME) test
framework will be reviewed; the connection between CPT and Lorentz invariance
in quantum field theory will be exposed; and various experimental CPT tests
with emphasis on matter--antimatter comparisons will be discussed.Comment: 6 page
Study of isospin violating excitation in
We study the reaction in the vicinity of mass
region. The isospin-violating excitation is accounted for by two major
mechanisms. One is electromagnetic (EM) transition and the other is strong
isospin violations. For the latter, we consider contributions from the
intermediate hadronic meson loops and - mixing as the major
mechanisms via the and s-channel transitions, respectively. By fitting the
recent KLOE data, we succeed in constraining the model parameters and
extracting the branching ratio. It shows that the
branching ratio is sensitive to the excitation line shape and background
contributions. Some crucial insights into the correlation between isospin
violation and Okubo-Zweig-Iizuka (OZI) rule evading transitions are also
learned.Comment: Revised version to appear in J. Phys.
Vus and lepton universality from kaon decays with the KLOE detector
KLOE has measured most decay branching ratios of Ks, Kl and K+/- mesons. It
has also measured the Kl and the K+- lifetime and determined the shape of the
form factors involved in kaon semileptonic decays. We present in the following
a description of the above measurements and a well organized compendium of all
of our data, with particular attention to correlations. These data provide the
basis for the determination of the CKM parameter Vus and a test of the
unitarity of the quark flavor mixing matrix. We also test lepton universality
and place bounds on new physics using measurements of Vus from Kl2 and Kl3
decays.Comment: 23 pages, 12 figures. Submitted to JHE
Measurement of the absolute branching ratios for semileptonic K+/- decays with the KLOE detector
Using a sample of over 600 million phi->K+K- decays collected at the Dafne
e+e- collider, we have measured with the KLOE detector the absolute branching
ratios for the charged kaon semileptonic decays, K+/- -> p0 e nu (gamma) (Ke3)
and K+/- -> p0 mu nu (gamma) (Kmu3). The results, BR(Ke3) = 0.04965 +/-
0.00038_{stat} +/- 0.00037_{syst} and BR(Kmu3) = 0.03233 +/- 0.00029_{stat} +/-
0.00026_{syst}, are inclusive of radiation. Accounting for correlations, we
derive the ratio Kmu3/Ke3 = 0.6511+/-0.0064. Using the semileptonic form
factors measured in the same experiment, we obtain V_{us}f_{+}(0) = 0.2141 +/-
0.0013.Comment: 13 pages, 3 figures, submitted to JHEP. v2: minor revisions required
by JHEP, v3: final version published by JHEP (replacement of 2 incorrect
affiliations)link: http://www.iop.org/EJ/abstract/1029-8479/2008/02/09
Precise measurements of the eta and the neutral kaon meson masses with the KLOE detector
We present precise measurements of the eta and K0 masses using the processes
phi to eta gamma, eta to gamma gamma and phi to Ks Kl, Ks to pi+ pi-. The K0
mass measurement, M_K=497.583 +/- 0.005 (stat) +/- 0.020 (syst) MeV, is in
acceptable agreement with the previous measurements but is more accurate. We
find m(eta) = 547.874 +/- 0.007 (stat) +/- 0.031 (syst) MeV. Our value is the
most accurate to date and is in agreement with two recent measurements based on
eta decays, but is inconsistent, by about 10 sigma, with a measurement of
comparable precision based on eta production at threshold.Comment: 15 pages, 8 figures Submitted to Physics Letters
Hadron Spectroscopy: Theory and Experiment
Many new results on hadron spectra have been appearing in the past few years
thanks to improved experimental techniques and searches in new channels. New
theoretical techniques including refined methods of lattice QCD have kept pace
with these developments. Much has been learned about states made of both light
(u, d, and s) and heavy (c, b) quarks. The present review treats light-quark
mesons, glueballs, hybrids, particles with a single c or b quark, charmonium,
and bottomonium states. Some prospects for further study are noted.Comment: 29 pages, 9 figures, to be published in Journal of Physics G. Further
updating of reference
Measurement of the K_L \to \pi\mu\nu form factor parameters with the KLOE detector
Using 328 pb^{-1}of data collected at DAFNE corresponding to 1.8
million decays, we have measured the form factor
parameters. The structure of the vector-current provides information
about the dynamics of the strong interaction; its knowledge is necessary for
evaluation of the phase-space integral required for measuring the CKM matrix
element and for testing lepton universality in kaon decays. Using a
new parametrization for the vector and scalar form factors, we find
=\pt(25.7\pm 0.6),-3, and =\pt(14.0\pm 2.1),-3,. Our
result for , together with recent lattice calculations of ,
and , satisfies the Callan-Trieman relatio
Study of the a_0(980) meson via the radiative decay phi->eta pi^0 gamma with the KLOE detector
We have studied the phi->a_0(980) gamma process with the KLOE detector at the
Frascati phi-factory DAPhNE by detecting the phi->eta pi^0 gamma decays in the
final states with eta->gamma gamma and eta->pi^+ pi^- pi^0. We have measured
the branching ratios for both final states: Br(phi->eta pi^0 gamma)=(7.01 +/-
0.10 +/- 0.20)x10^-5 and (7.12 +/- 0.13 +/- 0.22)x10^-5 respectively. We have
also extracted the a_0(980) mass and its couplings to eta pi^0, K^+ K^-, and to
the phi meson from the fit of the eta pi^0 invariant mass distributions using
different phenomenological models.Comment: 17 pages, 6 figures, submitted to Physics Letters B. Corrected typos
in eq.
Measurement of the charged kaon lifetime with the KLOE detector
We have measured the charged kaon lifetime using a sample of 15 \times 10^6
tagged kaon decays. Charged kaons were produced in pairs at the DA\PhiNE
\phi-factory, e^+e^- \to \phi \to K^+ K^-. The decay of a K^+ was tagged by the
production of a K^- and viceversa. The lifetime was obtained, for both charges,
from independent measurements of the decay time and decay lenght distributions.
From fits to the four distributions we find \tau = (12.347\pm0.030) ns.Comment: 13 pages, 14 figure