Measurement ofBd0−B¯d0Mi

Abstract

We report a determination of the B(0)(d)-&B_(0)(d) mixing parameter Deltam(d) based on the time evolution of dilepton yields in Upsilon(4S) decays. The measurement is based on a 5.9 fb(-1) data sample collected by the Belle detector at KEKB. The proper-time difference distributions for same-sign and opposite-sign dilepton events are simultaneously fitted to an expression containing Deltam(d) as a free parameter. Using both muons and electrons, we obtain Deltam(d) = 0.463+/-0.008 (stat)+/-0.016 (syst) ps(-1). This is the first determination of Deltam(d) from time evolution measurements at the Upsilon(4S). We also place limits on possible CPT violations.

Studies ofB0−B0mixing properties with inclusive dilepton events

“…The largest contributions to the systematic error for the ∆m d measurement come from the response function and the uncertainty in the B meson lifetime ratio τ B + /τ B 0 . Recent measurements [3] of this lifetime ratio have significantly reduced this systematic contribution since our first measurement [1]. The result of this dilepton analysis ∆m d = (0.503 ± 0.008 ± 0.010) ps −1 is in good agreement with the results from other methods used by Belle [8] and the current world average [3].…”

“…We extract ∆m d , f + /f 0 the ratio of Υ(4S) branching fractions to B + B − and B 0B0 , and the CPT violation parameters ℜ(cos θ) and ℑ(cos θ). Our previous determination of ∆m d using dilepton events from 5.9 fb −1 [1] treated f + /f 0 as a fixed parameter. Otherwise the results reported here use the same analysis method and include the earlier data and, therefore, supersede the previous values.…”

“…The techniques that have been employed to measure it in Υ(4S) → B 0B0 decays fall into two categories, namely inclusive and exclusive. Among the inclusive methods, the analysis of events where both B mesons decay into a final state that includes a high momentum lepton provides the largest event sample [1] and is well suited for further high precision measurements of the time evolution in the B 0B0 system. This system exhibits sensitivity not only to ∆m d , but also to other potentially interesting phenomena such as CP violation in mixing, the decay width difference between the two mass eigenstates and possible CPT violation in mixing [2].…”

Global three-parameter model for neutrino oscillations using Lorentz violation

“…The scale required to generate a neutrino-oscillation signal at the LSND energies E ' 10 ÿ2 GeV was found to be of order 10 ÿ19 GeV for a L e and c L e E. This result is compatible with the dimensionless ratio ' 10 ÿ17 of electroweak to Planck scales that might be expected to control suppression of Planck-scale physics. The sensitivity achieved is comparable to other searches for Lorentz and CPT violation using interferometric techniques in high-energy physics involving K oscillations [23], D oscillations [24], and B d oscillations [25][26][27][28], including ones with sidereal variations [29]. More generally, the SME sensitivities attainable with various types of neutrino searches can be comparable [18] to those achieved in the numerous experiments in astrophysics, atomic physics, optical physics, nuclear physics, and particle physics [1,2].…”

Limits on neutron Lorentz violation from pulsar timing

“…Experimental searches for Lorentz violation have thus far failed to produce any positive results. These searches have included studies of matter-antimatter asymmetries for trapped charged particles [2,3,4,5] and bound state systems [6,7], determinations of muon properties [8,9], analyses of the behavior of spin-polarized matter [10,11], frequency standard comparisons [12,13,14,15], Michelson-Morley experiments with cryogenic resonators [16,17], Doppler effect measurements [18,19], measurements of neutral meson oscillations [20,21,22,23], polarization measurements on the light from distant galaxies [24,25,26,27], analyses of the radiation emitted by energetic astrophysical sources [28,29], and others.Although the work by Kostelecký and Samuel on string theory [1] has been a major impetus for the study of Lorentz violation in the last ten years, there are also other situations in which Lorentz violation is a possibility. While there is no experimental evidence for Lorentz violation yet, there are numerous theoretical reasons to believe that Lorentz violation may be possible.…”