Violation Of CPT Symmetry Research Articles

Decoherence in quantum gravity: issues and critiques

An increasing number of papers have appeared in recent years on decoherence in quantum gravity at the Planck energy. We discuss the meaning of decoherence in quantum gravity starting from the common notion that quantum gravity is a theory for the microscopic structures of spacetime, and invoking some generic features of quantum decoherence from the open systems viewpoint. We dwell on a range of issues bearing on this process including the relation between statistical and quantum, noise from effective field theory, the meaning of stochasticity, the origin of non-unitarity and the nature of nonlocality in this and related contexts. To expound these issues we critique on two representative theories: One claims that decoherence in quantum gravity scale leads to the violation of CPT symmetry at sub-Planckian energy which is used to explain today's particle phenomenology. The other uses this process in place with the Brownian motion model to prove that spacetime foam behaves like a thermal bath. A companion paper will deal with intrinsic and fundamental decoherence which also bear on issues in classical and quantum gravity.

Possible test forCPTinvariance with correlated neutralBdecays

We study the breakdown of CPT symmetry which can occur in the decay process $B\overline{B}\ensuremath{\rightarrow}{l}^{\ifmmode\pm\else\textpm\fi{}}{X}^{\ensuremath{\mp}}f$ with f being a CP eigenstate. In this process, the standard model expectations for time-ordered semileptonic and hadronic events, i.e., which of the two decays takes place first, can be altered in the case that there is a violation of CPT symmetry. To illustrate this possibility, we identify and study several time-integrated observables. We find that an experiment with ${10}^{9}B\overline{B}$ pairs has the capability of improving the bound on the CPT violating parameter or perhaps observe CPT violation.

TESTING κ-POINCARÉ WITH NEUTRAL KAONS

In recent work on experimental tests of quantum-gravity-motivated phenomenological models, a significant role has been played by the so-called "κ" deformations of Poincaré symmetries. Sensitivity to values of the relevant deformation length λ as small as 5×10-33 m has been achieved in recent analyses comparing the structure of κ-Poincaré symmetries with data on the gamma rays we detect from distant astrophysical sources. We investigate violations of CPT symmetry which may be associated with κ-Poincaré in the physics of the neutral-kaon system. A simple estimate indicates that experiments on the neutral kaons may actually be more λ-sensitive than the corresponding astrophysical experiments, and may already allow to probe values of λ of order the Planck length.

Past Electron-Positrong−2Experiments Yielded Sharpest Bound onCPTViolation for Point Particles

In our past experiments on a single electron and positron we measured the cyclotron and spin-cyclotron difference frequencies omega_c and omega_a and the ratios a = omega_a/ omega_c at omega_c = 141 Ghz for e^- and e^+ and later, only for e^-, also at 164 Ghz. Here, we do extract from these data, as had not done before, a new and very different figure of merit for violation of CPT symmetry, one similar to the widely recognized impressive limit |m_Kaon - m_Antikaon|/m_Kaon < 10^-18 for the K-mesons composed of two quarks. That expression may be seen as comparing experimental relativistic masses of particle states before and after the C, P, T operations had transformed particle into antiparticle. Such a similar figure of merit for a non-composite and quite different lepton, found by us from our Delta a = a^- - a^+ data, was even smaller, h_bar |omega_a^- - omega_a^+|/2m_0 c^2 = |Delta a| h_bar omega_c/2m_0 c^2) < 3(12) 10^-22.

On the measurement of CP-violating energy differences in matter-antimatter enantiomers

Experiments are outlined for measuring possible, hypothetical CP-violating energy differences arising in chiral molecules and their antimatter-molecule enantiomers. While at present not within the reach of current experimental techniques due to the difficulty of synthesizing and trapping antimatter-molecules, such experiments are feasible, in principle, not just as thought experiments. The experiments help to clarify some fundamental concepts of C, P, and T symmetry violations in molecular physics with connections both to elementary panicle physics and cosmology. They would constitute potentially by far the most sensitive proposed test for CPT symmetry violation.

Космологические модели Вселенной с поворотом стрелы времени

Cosmological models of the Universe with reversal of time's arrow are considered. Formulations are given of the hypothesis of cosmological CPT symmetry suggested earlier by the writer, and of the hypothesis of an open model with many sheets, with negative spatial curvature, and with possible violation of CPT symmetry by an invariant combined charge. The statistical paradox of reversibility is discussed for these models. The small dimensionless parameter d/sup 2//a/sup 2/, which characterizes the mean spatial curvature of the Universe, is explained as the result of the evolution of the Universe through many successive cycles of expansion and contraction.