367 research outputs found
Tests of the Equivalence Principle with Neutral Kaons
We test the Principle of Equivalence for particles and antiparticles, using
CPLEAR data on tagged K0 and K0bar decays into pi^+ pi^-. For the first time,
we search for possible annual, monthly and diurnal modulations of the
observables |eta_{+-}| and phi_{+-}, that could be correlated with variations
in astrophysical potentials. Within the accuracy of CPLEAR, the measured values
of |eta_{+-}| and phi_{+-} are found not to be correlated with changes of the
gravitational potential. We analyze data assuming effective scalar, vector and
tensor interactions, and we conclude that the Principle of Equivalence between
particles and antiparticles holds to a level of 6.5, 4.3 and 1.8 x 10^{-9},
respectively, for scalar, vector and tensor potentials originating from the Sun
with a range much greater than the distance Earth-Sun. We also study
energy-dependent effects that might arise from vector or tensor interactions.
Finally, we compile upper limits on the gravitational coupling difference
between K0 and K0bar as a function of the scalar, vector and tensor interaction
range.Comment: 15 pages latex 2e, five figures, one style file (cernart.csl)
incorporate
Test of CPT Symmetry and Quantum Mechanics with Experimental data from CPLEAR
We use fits to recent published CPLEAR data on neutral kaon decays to
and to constrain the CPT--violation parameters
appearing in a formulation of the neutral kaon system as an open
quantum-mechanical system. The obtained upper limits of the CPT--violation
parameters are approaching the range suggested by certain ideas concerning
quantum gravity.Comment: 9 pages of uuencoded postscript (includes 3 figures
Estudo do efeito do ozônio gerado durante ensaios elétricos em equipamentos de segurança confeccionados em borracha natural
Asclepius or Hippocrates? Differing interpretations of post‐compulsory initial teacher training mentoring
The neutral kaon decays to : a detailed analysis of the CPLEAR data
A detailed analysis of neutral kaons decaying to \Pgpp \Pgpm \Pgpz\ is presented based on the complete data set containing half a million events. Time-dependent decay rate asymmetries are measured between initially tagged \PKz\ and \PaKz\ and for different regions of the phase space. These asymmetries, resulting from the interference between the CP-conserving decay amplitude of \PKzL\ and the decay amplitude of \PKzS\ -- either CP-violating or CP-conserving -- allow the determinationof the \PKzS\ parameters \etapmz\ (CP-violating) and \lampmz\ (CP-conserving), and also of the main i sospin components of the \PKzS\ decay amplitude. The branching ratio of \PKzS\ \Pgpp \Pgpm \Pgpz\ (CP-conserving) is deduced directly from \lampmz . In addition, we extract the slope parameters describing the energy dependence of the \PKzL \rightarrow \Pgpp \Pgpm \Pgpz Dalitz plot. The whole set of our results fits well within the current phenomenological picture of the neut ral-kaon system including CP violation and Chiral Perturbation Theory (ChPT)
Determination of the T- and CPT-violation parameters in the neutral-kaon system using the Bell-Steinberger relation and data from CPLEAR
Data from the CPLEAR experiment, together with the most recent world averages for some of the neutral-kaon parameters, were constrained with the Bell--Steinberger (or unitarity) relation, allowing the T-violation parameter \ree and the CPT-violation parameter \imd of the neutral-kaon mixing matrix to be determined with an increased accuracy: \ree = (164.9 \pm 2.5)\times 10^{-5}, \imd = ( 2.4 \pm 5.0)\times 10^{-5}. Moreover, the constraint allows the CPT-violation parameter for the neutral-kaon semileptonic decays, \rey, to be determined for the first time. The parameters \rexm and \imxp are given with an increased accuracy. The quantity , which enters the T-violation CPLEAR asymmetry previously published, is determined to be . The value obtained for \red is in agreement with the one resulting from a previous unconstrained fit and has a slightly smaller error
Measurement of the mass difference using semileptonic decays of tagged neutral kaons
We report on a new measurement of the \kl--\ks\ mass difference \dm\ using the CPLEAR full data sample of neutral-kaon decays to \semi. The result is \dm = (0.5295 \pm 0.0020_{\stat} \pm 0.0003_{\syst}) \times 10^{10}\ \hbs. It includes earlier data reported in Ref. \cite{deltam1}. A measurement of the \dsdq\ violating parameter \rex\ is also obtained
A determination of the CPT violation parameter Re() from the semileptonic decay of strangeness-tagged neutral kaons
We have improved by two orders of magnitude the limit currently available for the CPT violation parameter \red . To this purpose we have analyzed the full sample of neutral-kaon decays to \semi\ recorded in the CPLEAR experiment, where the strangeness of the neutral kaons was tagged at production and decay time. An appropriate function of the measured decay rates, including information from the analysis of \pip\pim\ decay channel, gives directly \red . The result is compatible with zero. Values for the parameters \imd, \rexm and \imxp were also obtained
Dispersion relation analysis of the neutral kaon regeneration amplitude in carbon
We apply a forward dispersion relation to the regeneration amplitude for kaon scattering on \PCtw using all available data. The CPLEAR data at low energies allow the determination of the net contribution from the subthreshold region which turns out to be much smaller than earlier evaluations, solving a long standing puzzle
Measurement of the neutral kaon regeneration amplitude in carbon at momenta below 1 GeV/c
The neutral kaon regeneration amplitude in carbon at momenta between 250 and 750~MeV/ was determined by measuring the interference of inherent and coherently regenerated \PKS\ amplitudes. This interference appears in the rates of initially pure (tagged) \PKz\ and \PaKz\ decaying to \Pgpp\Pgpm\ after crossing a carbon absorber
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