First direct observation of time-reversal non-invariance in the neutral-kaon system

Citation
A. Angelopoulos et al., First direct observation of time-reversal non-invariance in the neutral-kaon system, PHYS LETT B, 444(1-2), 1998, pp. 43-51
Citations number
12
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physics
Journal title
PHYSICS LETTERS B
ISSN journal
0370-2693 → ACNP
Volume
444
Issue
1-2
Year of publication
1998
Pages
43 - 51
Database
ISI
SICI code
0370-2693(199812)444:1-2<43:FDOOTN>2.0.ZU;2-6
Abstract
We report on the first observation of time-reversal symmetry violation thro ugh a comparison of the probabilities of (K) over bar(0) transforming into K-0 and K-0 into (K) over bar(0) as a function of the neutral-kaon eigentim e t. The comparison is based on the analysis of the neutral-kaon semilepton ic decays recorded in the CPLEAR experiment. There, the strangeness of the neutral kaon at time t = 0 was tagged by the kaon charge in the reaction <p (p)over bar> --> K (+/-) pi (+/-) K-0 ((K) over bar(0)) at rest, whereas th e strangeness of the kaon at the decay time t = tau was tagged by the lepto n charge in the final state. An average decay-rate asymmetry [R((K) over bar<INF>t=0</INF><SUP>0</SUP> --> e<SUP>+</SUP>pi<SUP>-</SUP>nu <INF>t=tau</INF>) - R(K<INF>t=0</INF><SUP>0</SUP> --> e<SUP>-</SUP>pi<SUP></SUP><(nu)over bar><INF>t=tau</INF>)/R((K) over bar<INF>t=0</INF><SUP>0</S UP> --> e<SUP>+</SUP>pi<SUP>-</SUP>nu<INF>t=tau</INF>) + R(K<INF>t=0</INF>< SUP>0</SUP> --> e<SUP>-</SUP>pi<SUP>+</SUP><(nu)over bar><INF>t=tau</INF>)] = (6.6 +/- 1.3<INF>stat</INF> +/- 1.0<INF>syst</INF>) X 10<SUP>-3 </SUP>was measured over the interval 1 tau(S) < tau < 20 tau(S), thus leadi ng to evidence for time-reversal non-invariance. (C) 1998 Elsevier Science B.V. All righs reserved.