Theory overview of testing fundamental symmetries
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Theory overview of testing fundamental symmetries Nick E. Mavromatos
© Springer International Publishing Switzerland 2014
Abstract I review first some theoretical motivations for violation of Lorentz and/or CPT Invariance. Although the latter symmetries may be violated in a quantum gravity setting, nevertheless there are situations in which these violations are due to a given classical background geometry that may characterised early epochs of our Universe, and in fact be responsible for the observed dominance of matter over antimatter in the Universe. In this way I estimate some of the coefficients of the Standard Model Extension (SME), which is a framework for a field theoretic study of such a breakdown of fundamental symmetries. Then I describe briefly some tests of these symmetries, giving emphasis in low-energy antiproton physics and electric dipole moment measurements, of interest to this conference. I also mention the rˆole of entangled states of neutral mesons in providing independent measurements of T(ime reversal) and CP Violation, thus providing independent tests of CPT symmetry, as well as novel (“smoking-gun” type) tests of decoherence-induced CPT violation, which may characterise some models of quantum gravity. Keywords Lorentz symmetry · CPT violation · Phenomenology
1 Theoretical motivations for Lorentz and CPT violation The theory of Quantum Gravity is still elusive and far from any experimental verification. Nevertheless, in the last decade there have been significant improvements in the precision of terrestrial and astrophysical instrumentation, which resulted in stringent bounds being placed on several models of quantum gravity available in the literature so far. Most of these Proceedings of the 11th International Conference on Low Energy Antiproton Physics (LEAP 2013) held in Uppsala, Sweden, 10-15 June, 2013 N. E. Mavromatos () King’s College London, Department of Physics, Strand, London WC2R 2LS, UK e-mail: [email protected] Present Address: N. E. Mavromatos CERN, Physics Department, Theory Division, CH-1211 Geneva 23, Switzerland
N. E. Mavromatos
models predict a breakdown of fundamental symmetries, such as (local) Lorentz invariance and CPT symmetry [1]. On the other hand, it is also possible that our Universe, at early epochs, was not characterised by the Robertson-Walker geometry, but by other, non-trivial background space times which may violated Lorentz and CPT symmetries in such a way that some remnants of such violations remained today, albeit small. In the latter case, the relics of such violations today may not be necessarily suppressed by the Planck scale, thus having a greater chance of being observed in the foreseeable future. In the first part of the talk I will discuss such a case, with the hope of better motivating the experimental searches for Lorentz and CPT violation. Lorentz & CPT violating geometries in the early universe The simplest example of such a geometry, is provided [2] by an extension of the gravitational sector of the standard model to include
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