Tests of CPT invariance for neutral-flavoured-meson--antimeson mixing

We focus on two aspects of CPT invariance in neutral-meson--antimeson ($M^0 \bar M^0$) mixing: 1. Tests of CPT invariance, using only the property of ``lack of vacuum regeneration'', which occurs as a part of the well-known Lee--Oehme--Yang (LOY) theory; 2. Methods for extracting the CPT-violating mixing parameter $\theta$ through explicit calculations by using the LOY-type theory fully. In the latter context, we demonstrate the importance of the C-even $| M^0 \bar M^0>$ state. In particular, by measuring the time dependence of opposite-sign dilepton events arising from decays of the C-even and C-odd $| M^0 \bar M^0>$ states, $\theta$ may be disentangled from the parameters $\lambda_+$ and $\bar \lambda_-$ characterizing violations of the $\Delta F = \Delta Q$ rule. Furthermore, these two parameters may also be determined. The same is true if one uses like-sign dilepton events arising from only the C-even $| M^0 \bar M^0>$ state.Comment: 13 pages, no figures, Revtex; change in title, extensive changes in the presentation, version to be published in Eur. Phys. J.

Dilepton asymmetries at BB factories in search of ΔB=−ΔQ\Delta B =- \Delta Q transitions

In order to detect the possible presence of $\Delta B = - \Delta Q$ amplitudes in neutral $B$ meson decays, we consider the measurement of decay time asymmetries involving like-sign dilepton events at the $B$ factories.Comment: 5 pages, latex, no fig

On the Orthogonality of Independently Propagating States as Occurring in the Lee-Oehme-Yang Theory

We generalize a theorem by Khalfin, originally derived for the states $| F_1 > = | M^0>$, $| F_2 > = |\bar M^0>$, where $M^0$ is a neutral flavoured meson (e.g., $K^0$ or $B_d^0$), by assuming CPT invariance. Dispensing with CPT invariance and allowing for an arbitrary pair of orthogonal states $| F_{1,2}>$, we show that any linear combinations $| P_a > = p_a | F_1 > + q_a | F_2>$ and $| P_b > = p_b | F_1 > - q_b | F_2>$, if postulated to be independently propagating in time, as in the Lee--Oehme--Yang Theory, must be mutually orthogonal. This implies a reciprocity relation: equality of the probabilities of the transitions $| F_1 > \leftrightarrow | F_2>$. Also implied is another relation involving the coefficients $p_{a,b}$, $q_{a,b}$, which can be interpreted as $\mathrm{Im} \theta = 0$, where $\theta$ is the rephasing-invariant parameter describing CPT violation in $M^0 \bar M^0$ mixing for Khalfin's choice of $| F_{1,2}>$. The states $| F_{1,2}>$ of \emph{our} theorem need not form a particle-antiparticle pair, nor even be restricted to particle physics.Comment: 9 pages, LATEX, no figues. Misprints corrected and part of the presentation changed, version to be published in Phys. Rev.

Two-Particle Correlations and Meson-Antimeson Mixing Effects

We discuss 2-particle correlations which arise in the time evolution of C-odd and C-even meson--antimeson states of flavoured neutral mesons. In order to keep our discussion general, we do not use the Weisskopf -- Wigner approximation. Possible deviations from quantum-mechanical coherence effects are parameterized by a so-called decoherence parameter $\zeta$. In particular, we study the $\zeta$-dependence of the asymmetry of unlike and like-flavoured events which was recently observed experimentally in the $K^0 \bar{K}^0$ system. In this $\zeta$-dependence, we point out some important general features which do not rely on the Weisskopf -- Wigner approximation. Some other related results are derived more generally than in the literature.Comment: 12 pages, revtex, no figure

Two-Particle Correlations and B0Bˉ0B^0\bar{B}^0 Mixing

We study the EPR correlation implied by the entangled wavefunction of the $B^0\bar{B}^0$ pair created by the $\Upsilon$(4S) resonance. The analysis uses the basis provided by the mass eigenstates $B_1,B_2$ rather than the flavour states $B^0, \bar{B}^0$. Data on the inclusive dilepton charge ratio are close to the expectation of quantum mechanics, but nearly 8 standard deviations away from that of complete decoherence.Comment: 10 pages, Latex, no figure

Probing space-time structure of new physics with polarized beams at the ILC

At the International Linear Collider large beam polarization of both the electron and positron beams will enhance the signature of physics due to interactions that are beyond the Standard Model. Here we review our recently obtained results on a general model independent method of determining for an arbitary one-particle inclusive state the space-time structure of such new physics through the beam polarization dependence and angular distribution of the final state particle.Comment: 6 pages, plain latex, Talk given at LCWS06, Linear Collider Workshop, 9-13 March 2006, Bangalore, Indi

CP-Violating Correlations between Lepton-Charge and Jet-Charge in Z -> b\bar b events

Correlations that signal direct CP violation in the bottom sector are suggested. They need data on $Z\to b\bar b$ events which consist of a bottom hadron decay into an exclusive semileptonic channel $h \ell \nu$ (where $h$ is a hadron), and the other bottom hadron decay into a multi-body final state that manifests as a jet in the opposite hemisphere.Comment: 10 pages, Latex, no figures, expanded versio

Testing the ΔS=ΔQ\Delta S=\Delta Q Rule with Exclusive Semi-Leptonic Kaon Decays

We consider the possibility of violations of the selection rule $\Delta S=\Delta Q$ at an appreciable level in {\it exclusive} semi-leptonic decays of Kaons. At $\Phi$-Factories, intense Kaon beams will be available and will probe among others, the semi-leptonic decays $K_{l4}$ and $K_{l3\gamma}$ in addition to $K_{l3}$ and could provide novel testing grounds for the $\Delta S=\Delta Q$ rule. In particular, the branching ratio of $K_{l3\gamma}$ is non-negligible and could be used to probe new phenomena associated with the violation of this selection rule. Furthermore, we modify certain di-lepton event rate ratios and asymmetries and time asymmetries that have been constructed by Dass and Sarma for di-lepton events from Beon decays to test the $\Delta B=\Delta Q$ at the $\Upsilon (4S)$, to the Kaon system at the $\phi(1020)$. We find that the large width of the $K_S$ relative to that of $K_L$ plays an important role in enhancing some of the time asymmetries.Comment: 10 pages, Plain Latex, To be run twice

Effects of Possible ΔB=−ΔQ\Delta B =- \Delta Q Transitions in Neutral BB Meson Decays}

We explore the possibility that the existing data on like-sign dileptons at the $\Upsilon (4S)$ resonance consist of events arising from $B_{d}^0 -\bar B_{d}^0$ mixing and also from $\Delta B = - \Delta Q$ transitions. The consequences of these nonstandard transitions for certain time-asymmetries which are likely to be measured at the $B$ factories are studied.Comment: {\LARGE \bf 10 pages, no figures, process using latex, TIFR/TH/93-5