Searcharxiv⌕ Search

arXiv subjects

G. V. Dass

Publications and source records attributed to G. V. Dass.

11 recordsLinked to original sources
arXiv2002

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 $\mathrm{Im} θ= 0$, where $θ$ 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.

hep-ph↗
arXiv2002

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 $θ$ 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, $θ$ may be disentangled from the parameters $λ_+$ and $\bar λ_-$ characterizing violations of the $ΔF = ΔQ$ 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.

hep-ph↗
arXiv2001

Testing the Wigner - Weisskopf approximation by using neutral-meson - antimeson correlated states

We phenomenologically decompose the Weisskopf--Wigner approximation, as applied to the neutral flavoured meson complexes, into three pieces and propose tests for these pieces. Our tests hold for general decay amplitudes and $M^0$--$\bar M^0$ mixing parameters. We concentrate on C-odd $M^0 \bar M^0$ states and stress the importance of such tests in view of the variety of physics extracted from measurements on such complexes. Studying the feasibility of the tests confines one to the $K^0 \bar K^0$ system at present. In particular, we show that the time dependence of the correlated decay $ϕ\to K^0 \bar K^0 \to 2 (π^+ π^-)$ is determined solely by the WWA and provides thus a clean test of it.

hep-ph↗
arXiv2000

Testing CPT invariance by using C-even neutral-meson--antimeson correlated states

We consider the decays of a correlated neutral-meson--antimeson state with C-parity +1. We show that there is CPT noninvariance in the mixing of the neutral mesons if, for any two decay modes f and g, the decay rate has a component R_A which is antisymmetric under the interchange of the decay times t_1 and t_2. In particular, one may cleanly extract the CPT-noninvariance parameter with the help of R_A by using opposite-sign dilepton events.

hep-ph↗
arXiv1999

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 $ζ$. In particular, we study the $ζ$-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 $ζ$-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.

hep-ph↗
arXiv1997

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

We study the EPR correlation implied by the entangled wavefunction of the $B^0\bar{B}^0$ pair created by the $Υ$(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.

hep-ph↗
arXiv1997

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 $h \ell ν$ (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.

hep-ph↗
arXiv1996

The $ΔB = - ΔQ$ transitions and $B_d \leftrightarrow \bar B_d$ oscillations

We estimate the product of the relative strength of the $ΔB = -ΔQ$ amplitude in the decay $B_d^0 \rightarrow D^{*} \ell \bar ν_{\ell }$ and the width-difference parameter $y$. For this we have used the data on time-dependence of $B_{d}^0\bar B_{d}^0$ oscillations in Z decays and the fraction of like-sign dilepton events at the $Υ(4S)$.

hep-ph↗
arXiv1993

Effects of Possible $ΔB =- ΔQ$ Transitions in Neutral $B$ Meson Decays}

We explore the possibility that the existing data on like-sign dileptons at the $Υ(4S)$ resonance consist of events arising from $B_{d}^0 -\bar B_{d}^0$ mixing and also from $ΔB = - ΔQ$ transitions. The consequences of these nonstandard transitions for certain time-asymmetries which are likely to be measured at the $B$ factories are studied.

hep-ph↗