Search for Violation ofCPTand Lorentz Invariance inBs0Meson Oscillations

Abstract

We present the first search for CPT-violating effects in the mixing of B 0 s mesons using the full Run II data set with an integrated luminosity of 10.4 fb −1 of proton-antiproton collisions collected using the D0 detector at the Fermilab Tevatron Collider. We measure the CPT-violating asymmetry in the decay B 0 s → µ ± D ± s as a function of celestial direction and sidereal phase. We find no evidence for CPT-violating effects and place limits on the direction and magnitude of flavor-dependent CPTand Lorentz-invariance violating coupling coefficients. We find 95% confidence intervals of ∆a ⊥ < 1.2 × 10 −12 GeV and (−0.8 < ∆aT − 0.396∆aZ < 3.9) × 10 −13 GeV.PACS numbers: 11.30. Cp, 13.20.He, 14.40.Nd Lorentz invariance requires that the description of a particle is independent of its direction of motion or boost velocity. The Standard Model Extension (SME) [1] provides a framework for potential Lorentz and CPT invariance violation (CPTV), suggesting that such violations can occur at the Planck scale but still result in potentially observable effects at currently available collider energies. The process of neutral meson oscillations is described by a 2 × 2 effective Hamiltonian with mass eigenvalues of the propagating particles having very small differences between them that drive the oscillation probability. For the B 0 s -B 0 s system, the fractional difference between the eigenvalues is of the order of 10 −12 . Due to this, B 0 s -B 0 s oscillations form an interferometric system that is very sensitive to small couplings between the valence quarks and a possible Lorentz-invariance violating field, making it an ideal place to search for new physics [2]. The measurement of the like-sign dimuon asymmetry by the D0 Collaboration [3] shows evidence of anomalously large CP-violating effects. This is currently one of the few significant deviations from the standard model of particle physics. One of the interpretations of this effect could be a CPT-invariant CP violation (CPV) in neutral B-meson mixing. The propagating "light" (L) and "heavy" (H) mass eigenvalues of the B 0 s -B 0 s system can be written as [4]:If the complex parameter ξ s is zero, CPT is conserved and CPV is due to |q/p| = 1 so that the oscillation probability). An alternative interpretation is that the asymmetry could arise from T-invariant CPV in B 0 s -B 0 s mixing [5] where |q/p| = 1, but ξ s is non-zero so that the probability of non-oscillation or oscillation back to the original state where ∆a µ is a four vector direction and magnitude in space-time characterizing Lorentz-invariance violation which in the SME is given by ∆a µ = r s a s µ −r b a b µ where a q µ are Lorentz-violating coupling constants for the two valence quarks in the B 0 s meson, and where the factors r q allow for quark-binding or other normalization effects. The four-velocity of the B 0 s meson is given by β µ = γ(1, β), β µ ∆a µ is the difference between the diagonal elements of the effective Hamiltonian, and the mass and decay rate differences of the mass eigenstates are...

Electroweak precision tests of the Standard Model after the discovery of the Higgs boson

“…It should be noted that this value was not fully corrected for the underlying assumption of the PYTHIA event generator of a fixed weak mixing angle for all fermions. A partial correction was achieved by comparing the PYTHIA interpretation with a modified version of RESBOS, which uses different values of the effective weak mixing angle for leptons and up-and down-quarks [238]. The dominant uncertainty in the final measurements is due to the limited data statistics.…”

Quark-sector Lorentz violation in Z-boson production

“…Experiments involving hadrons provide opportunities to constrain the comparatively unexamined CPT-and Lorentz-violating effects on mesons, baryons, and underlying quark and gluon (parton) degrees of freedom [12]. To date, d = 3 quark coefficients have been constrained using K, D, B d , and B s meson oscillations [13][14][15][16][17][18][19][20][21][22][23][24][25]. Relatively recently, techniques of chiral perturbation theory have established connections between minimal effective meson and baryon coefficients and parton coefficients, leading to several constraints on d = 3, 4 quark and ed = 4 gluon coefficients using low-energy experiments and high-energy astrophysical sources [26][27][28][29][30].…”

Quark-sector Lorentz violation in $Z$-boson production

“…Experiments involving hadrons provide opportunities to constrain the comparatively unexamined CPT-and Lorentz-violating effects on mesons, baryons, and underlying quark and gluon (parton) degrees of freedom [12]. To date, d = 3 quark coefficients have been constrained using K, D, B d , and B s meson oscillations [13][14][15][16][17][18][19][20][21][22][23][24][25]. Relatively recently, techniques of chiral perturbation theory have established connections between minimal effective meson and baryon coefficients and parton coefficients, leading to a number of constraints on d = 3, 4 quark and d = 4 gluon coefficients using low-energy experiments and highenergy astrophysical sources [26][27][28][29][30].…”