Short-lived Neutral Kaons Research Articles

Calculation of atmospheric high-energy neutrino spectra and the measurement data of IceCube and ANTARES experiments

Presented are results of calculation of the atmospheric neutrino spectra in the energy range from 100 GeV to 10 PeV using the QGSJET-II and SIBYLL 2.1 models of hadron–nuclear interactions and two experimentally based Zatsepin–Sokol’skaya and Hillas–Gaisser models of the cosmic ray spectrum. It is shown that rare decays of short-lived neutral kaons produce about one third of the flux of electron neutrinos and up to 10% of muon neutrinos at energies above 100 TeV. The calculated spectra agree satisfactorily with the IceCube and ANTARES measurement data. The measurement errors leave open the possibility of a contribution from decays of charmed particles to fluxes of muon neutrinos with energies above 500 TeV and electron neutrinos with energies above 30 TeV.

The comparison of the calculated atmospheric neutrino spectra with the measurements of IceCube and ANTARES experiments

We calculate the atmospheric neutrino spectra in the energy range of 102 − 107 GeV using the hadronic models QGSJET-II, SIBYLL 2.1 and the parameterizations of cosmic ray spectra by Zatsepin-Sokolskaya, and Hillas-Gaisser supported by experiments. It is shown that rare decay mode of short-lived neutral kaons produce about 30% of the electron neutrino flux and up to 10% of muon neutrinos at energies above 200 TeV. Comparative analysis of our calculations based on the Ƶ(E, h)-function approach and those obtained with use of the new MCEq-method (A. Fedynitch et al.) demonstrates the close agreement of both calculations. The comparison of calculated neutrino spectrum to the experimental data shows that IceCube and ANTARES measurements leave opened window for the prompt neutrino flux contribution obtained with the quark-gluon string model (QGSM).

Exploration of Lorentz violation in neutral-kaon decay

The KLOE Collaboration recently reported bounds on the directional dependence of the lifetime of the short-lived neutral kaon KS0 with respect to the dipole anisotropy of the cosmic microwave background. We interpret their results in an effective field theory framework developed to probe the violation of Lorentz invariance in the weak interaction and previously applied to semileptonic processes, in particular β decay. In this approach a general Lorentz-violating tensor χμν is added to the standard propagator of the W boson. We perform an exploratory study of the prospects to search for Lorentz violation in nonleptonic decays. For the kaon, we find that the sensitivity to Lorentz violation is limited by the velocity of the kaons and by the extent to which hadronic effects can be calculated. In a simple model we derive the KS0 decay rate and calculate the asymmetry for the lifetime. Using the KLOE data, limits on the values of χμν are determined.

The History of Cosmic Ray Studies after Hess

The discovery of cosmic rays by Victor Hess was confirmed with balloon flights at higher altitudes by Kolhörster. Soon the interest turned into questions about the nature of cosmic rays: gamma rays or particles? Subsequent investigations have established cosmic rays as the birthplace of elementary particle physics. The 1936 Nobel prize was shared between Victor Hess and Carl Anderson. Anderson discovered the positron in a cloud chamber. The positron was predicted by Dirac several years earlier. Many new results came now from studies with cloud chambers and nuclear emulsions. Anderson and Neddermeyer saw the muon, which for some time was considered to be a candidate for the Yukawa particle responsible for nuclear binding. Lattes, Powell, Occhialini and Muirhead clarified the situation by the discovery of the charged pions in cosmic rays. Rochester and Butler found Vʼs, which turned out to be short-lived neutral kaons decaying into a pair of charged pions. Λʼs, Σʼs and Ξʼs were found in cosmic rays using nuclear emulsions. After that period, accelerators and storage rings took over. The unexpected renaissance of cosmic rays started with the search for solar neutrinos and the observation of the supernova 1987A and other accelerators in the sky. With the observation of neutrino oscillations one began to look beyond the standard model of elementary particles. After 100 years of cosmic ray research we are again at the beginning of a new era, and cosmic rays may contribute to solve the many open questions, like dark matter and dark energy, by providing energies well beyond those of earth-bound accelerators.

Early developments: Particle physics aspects of cosmic rays

Cosmic rays is the birthplace of elementary particle physics. The 1936 Nobel prize was shared between Victor Hess and Carl Anderson. Anderson discovered the positron in a cloud chamber. The positron was predicted by Dirac several years earlier. In subsequent cloud chamber investigations Anderson and Neddermeyer saw the muon, which for some time was considered to be a candidate for the Yukawa particle responsible for nuclear binding. Measurements with nuclear emulsions by Lattes, Powell, Occhialini and Muirhead clarified the situation by the discovery of the charged pions in cosmic rays. The cloud chamber continued to be a powerful instrument in cosmic ray studies. Rochester and Butler found V’s, which turned out to be shortlived neutral kaons decaying into a pair of charged pions. Also Λ’s, Σ’s, and Ξ’s were found in cosmic rays. But after that accelerators and storage rings took over. The unexpected renaissance of cosmic rays started with the search for solar neutrinos and the observation of the supernova 1987A. Cosmic ray neutrino results were best explained by the assumption of neutrino oscillations opening a view beyond the standard model of elementary particles. After 100years of cosmic ray research we are again at the beginning of a new era, and cosmic rays may contribute to solve the many open questions, like dark matter and dark energy, by providing energies well beyond those of accelerators.

A new measurement of Re(ε′/ε) by the NA48 experiment at CERN and future plans

The NA48 experiment at CERN detects concurrently the four decay modes into two pions of the long and short lived neutral kaons. During 1998 and 1999 data taking, statistics in each mode was increased by a factor eight, with respect to the 1997 published data. A new measurement of the double ratio of the four modes has been obtained from these data. This new result on the direct CP violation parameter Re(ε′/ε) is (15.0 ± 2.7) × 10 −4 which, combined with the previous NA48 published result gives Re(ε′/ε) = (15.3 ± 2.6) × 10 −4

A novel application of bent crystal channeling to the production of simultaneous particle beams

Channeling of a 450 GeV/ c proton beam through a bent silicon crystal has found a novel application to the production of simultaneous particle beams. A pair of simultaneous, nearly-collinear beams of long- and short-lived neutral kaons has thereby been derived. These beams form an integral part of an experiment, NA48, at CERN, designed to measure the CP-violation parameter ϵ′ ϵ with high precision.

Testing the non-locality of quantum theory in two-kaon systems

An idea for testing the non-local character of quantum theory in systems made of two neutral kaons is suggested. Such tests require detecting two long-lived or two short-lived neutral kaons in coincidence, when copper slabs are either interposed on or removed from their paths. They may be performed at an asymmetric Φ 0−factory. They could answer some questions raised by the EPR paradox and Bell's inequalities. If such tests are performed and if predictions of quantum mechanics and standard theory of kaon regeneration are verified experimentally, all descriptions of the relevant phenomena in terms of local interactions will be ruled out in principle with the exception of very peculiar ones, which imply the existence of hidden variables, of different kinds of kaons corresponding to different values of the hidden variables, and, for some of these kaons, of regeneration probabilities enhanced by a factor of the order of 400 or more over the average. Of course, the experiment may also reveal a break down of quantum theory.

Comparison of the vector- and axial-vector-meson exchange contributions to the decay rate of the short-lived neutral kaon into two photons.

The contributions of the charged axial-vector mesons b(1235) and a/sub 1/(1270) as exchange particles in the decay mode K/sub S/..--> gamma gamma.. are compared with those of the vector mesons p(770), ..omega..(783), phi(1020), and psi(3097). The range of the rates of decay obtained for several choices of the cutoff mass falls within the limits of the value GAMMA(K/sub S/..-->..2..gamma..)GAMMA(K/sub S/..-->..all) = (2.4 +- 1.2) x 10/sup -6/ obtained recently by the NA31 experimental group at the CERN SPS

Re-evaluation of the relative decay rate of long-lived and short-lived neutral kaons into two neutral pions

Some time ago theCP-violating decay K L 0 → π0π0 was discovered by a CERN-RHEL-Aachen group, using a multiplate spark chamber arrangement near a K L 0 beam, derived from the CERN proton synchrotron. These data have been reanalysed performing a least-squares fit to each event. The average errors of directions and energies of the detected photons have been experimentally determined on samples of 4-shower and 6-shower events. A normalization on regenerated K S 0 → 2π0 decays has been used. The value of |η00|=|A(K L 0 → 2π0)/A(K S 0 → 2π0)|==(2.4±0.5)·10−3 is consistent withT violation andCPT conservation in K L 0 → 2π decay and with the existence of a superweak interaction.

Nonorthogonality of the Long- and Short-Lived Neutral Kaon States and Phenomenological Analysis of Experiments onCPNonconservation inK0Decay

It is noted that the nonzero charge asymmetry in the ${({K}_{L})}_{e3}$ decay demonstrates the nonorthogonality of the ${{K}_{L}}^{0}$ and ${{K}_{S}}^{0}$ states. The result of the foregoing Letter on the charge asymmetry, combined with other measurements relevant to $\mathrm{CP}$ nonconservation in $K$ decay, are found to be consistent with a phenomenological analysis, which yields a pion-pion scattering phase shift consistent with other indirect observations only if the mass difference ${m}_{L}\ensuremath{-}{m}_{S}$ is negative.