TestingCPTwith Anomalous Magnetic Moments

Abstract

A theoretical framework is introduced that describes possible CPT-violating effects in the context of quantum electrodynamics. Experiments comparing the anomalous magnetic moments of the electron and the positron can place tight limits on CPT violation. The conventional figure of merit adopted in these experiments, involving the difference between the corresponding g factors, is shown to provide a misleading measure of the precision of CPT limits. We introduce an alternative figure of merit, comparable to one commonly used in CPT tests with neutral mesons. To measure it, a straightforward extension of current experimental procedures is proposed. With current technology, a CPT bound better than about 1 part in 10 20 is attainable. [S0031-9007(97)03884-2] PACS numbers: 11.30. Er, 12.20.Fv, 13.40.Em, 14.60.Cd The CPT theorem [1] is a powerful result holding for local relativistic quantum field theories of point particles in flat spacetime. It states that such theories must be invariant under the combined operations of charge conjugation C, parity reversal P, and time reversal T. Among the implications of the theorem are the equality of particle and antiparticle masses and lifetimes.Invariance under CPT has been tested in a variety of experiments [2]. The tightest bound published to date arises from experiments with the neutral kaon system [3], where the CPT figure of merit(1) is known to be smaller than 2 parts in 10 18 . This remarkable precision is possible because neutral-kaon oscillations provide a natural interferometer with dimensionless sensitivity controlled by the mass difference between the physical K L and K S states: j͑m L 2 m S ͒͞m K j Ӎ 10 214 . The quoted precision for r K is thus attained via measurements with a precision of about 1 part in 10 4 .Atomic experiments have also confirmed CPT symmetry. High-precision comparisons of the anomalous magnetic moments of the electron and positron currently provide the most stringent bounds on CPT violation in lepton systems [4]. Denote the electron and positron g factors by g 2 and g 1 , respectively. Then, a conventional figure of merit used in these experiments is [2]which is known to be smaller than 2 parts in 10 12 . The experiments confine isolated single electrons or positrons in a Penning trap for the indefinite periods [4,5] and measure their cyclotron and anomaly frequencies to a precision of better than 1 part in 10 8 . These frequencies can be combined to determine g 2 2, which is of order 10 23 , and hence to yield the limit on r g .The figure of merit r g is poorer than r K by about 6 orders of magnitude, even though the experimental measurements involved in the g 2 2 experiments are about 4 orders of magnitude sharper. This discrepancy originates in the difference between the quantities entering the dimensionless figures of merit. One is a mass (energy) difference while the other is a coupling difference. Indeed, all CPT tests to date have looked for differences between particles and antiparticle masses, lifetimes, or couplings. An important ...

Threshold analyses and Lorentz violation

“…This dynamical framework is constructed to contain all Lorentz-and CPT-violating lagrangian terms consistent with coordinate invariance, a fundamental requirement to be discussed below. The SME has provided the basis for numerous experimental Lorentz-and CPT-violation searches involving hadrons [13][14][15], protons and neutrons [16][17][18], electrons [18][19][20][21][22], photons [23][24][25][26][27], muons [28], and neutrinos [8,29,30].…”

The Lorentz-Violating Extension of the Standard Model

“…The SME is a dynamical model constructed to contain all Lorentz-and CPT-violating lagrangian terms consistent with coordinate independence, which is a fundamental requirement to be discussed below. To date, numerous Lorentz-and CPT-violation tests involving hadrons [8][9][10][11][12][13][14][15][16][17][18][19][20][21], protons and neutrons [22][23][24][25][26][27][28][29][30][31], electrons [31][32][33][34][35][36][37][38][39][40][41], photons [42][43][44][45][46][47], muons [48][49][50], and neutrinos [2,[51][52][53][54] have been analysed or identified within th...…”

Lorentz violation andαdecay

“…Sensitive searches for Lorentz violation have included studies of matter-antimatter asymmetries for trapped charged particles [13,14,15] and bound state systems [16,17], determinations of muon properties [18,19], analyses of the behavior of spin-polarized matter [20,21], frequency standard comparisons [22,23,24,25], Michelson-Morley experiments with cryogenic resonators [26,27,28], Doppler effect measurements [29,30], measurements of neutral mesons [31,32,33,34,35,36], polarization measurements on the light from distant galaxies [37,38,39,40], high-energy astrophysical tests [41,42,43,44] and others. The results of these experiments set bounds on various SME coefficients.…”