In this work we study temporal quantum correlations, quantified by Leggett-Garg (LG) and LG-type inequalities, in the $B$ and $K$ meson systems. We use the tools of open quantum systems to incorporate the effect of decoherence which is quantified by a single phenomenological parameter. The effect of $CP$ violation is also included in our analysis. We find that the LG inequality is violated for both $B$ and $K$ meson systems, the violation being most prominent in the case of $K$ mesons and least for ${B}_{s}$ system. Since the systems with no coherence do not violate LGI, incorporating decoherence is expected to decrease the extent of violation of LGI and is clearly brought out in our results. We show that the expression for the LG functions depends upon an additional term, apart from the experimentally measurable meson transition probabilities. This term vanishes in the limit of zero decoherence. On the other hand, the LG-type parameter can be directly expressed in terms of transition probabilities, making it a more appropriate observable for studying temporal quantum correlations in neutral meson systems.In this work we study temporal quantum correlations, quantified by Leggett-Garg (LG) and LG-type inequalities, in the $B$ and $K$ meson systems. We use the tools of open quantum systems to incorporate the effect of decoherence which is quantified by a single phenomenological parameter. The effect of $CP$ violation is also included in our analysis. We find that the LG inequality is violated for both $B$ and $K$ meson systems, the violation being most prominent in the case of $K$ mesons and least for ${B}_{s}$ system. Since the systems with no coherence do not violate LGI, incorporating decoherence is expected to decrease the extent of violation of LGI and is clearly brought out in our results. We show that the expression for the LG functions depends upon an additional term, apart from the experimentally measurable meson transition probabilities. This term vanishes in the limit of zero decoherence. On the other hand, the LG-type parameter can be directly expressed in terms of transition probabilities, making it a more appropriate observable for studying temporal quantum correlations in neutral meson systems.

arXiv:1802.04265Physical review. D/Physical review. D.Mar 26, 201834 citations

Study of Quantum Decoherence in Neutral B Meson pairs produced at the $\Upsilon(5S)$ ResonanceStudy of Quantum Decoherence in Neutral B Meson pairs produced at the $\Upsilon(5S)$ Resonance

Louise Beriet

This thesis presents the development and validation of an analysis framework to study quantum decoherence in neutral B-meson pairs produced at the $\Upsilon(5S)$ resonance, using Monte Carlo simulated data from the Belle experiment. Unlike the $\Upsilon(4S)$ , the $\Upsilon(5S)$ provides access to both antisymmetric ( $C=-1$ ) and symmetric ( $C=+1$ ) quantum states through the channels $B^0\bar{B}^0$ , $B^{0*}\bar{B}^0+c.c.$ , and $B^{0*}\bar{B}^{0*}$ . Decoherence effects are studied with the Partial Spontaneous Disentanglement model, which introduces a fraction $\zeta$ of $B^{0*}\bar{B}^{*0}$ pairs disentangled at production. The analysis exploits the decay times of both neutral B mesons, for which time-dependent probability density functions are derived and extended to include detector-resolution effects. The framework is first validated on Signal Monte Carlo samples, where one-dimensional fits to $\Sigma t$ successfully recover the expected decoherence values for both entangled and disentangled configurations. Fits to Generic Monte Carlo samples, which include realistic backgrounds and event compositions, reveal strong correlations between the decoherence parameter and flavour-tagging wrong-tag fractions, particularly in the $C=-1$ channels. The results from these fits show significant deviations from expected $\zeta$ values and large uncertainties. Pure Toy Monte Carlo studies confirm that the fitter behaves linearly with respect to the injected decoherence parameter and show only small biases consistent with those observed in the nominal fits, but too small to fully explain them. To address the limitations of the single fits, a two-dimensional analysis in $(\Delta t,\Sigma t)$ is developed. By exploiting the full time-dependent information, the two-dimensional fit significantly reduces the statistical uncertainty on the decoherence parameter from $\sim\mathcal{O}(10\%)$ to $\sim\mathcal{O}(4\%)$ and mitigates correlations with the flavour-tagging parameters. This work constitutes a proof of concept for future analyses on Belle data and demonstrates the potential of the $\Upsilon(5S)$ system for studying quantum entanglement and decoherence in neutral B mesons.This thesis presents the development and validation of an analysis framework to study quantum decoherence in neutral B-meson pairs produced at the $\Upsilon(5S)$ resonance, using Monte Carlo simulated data from the Belle experiment. Unlike the $\Upsilon(4S)$, the $\Upsilon(5S)$ provides access to both antisymmetric ($C=-1$) and symmetric ($C=+1$) quantum states through the channels $B^0\bar{B}^0$, $B^{0*}\bar{B}^0+c.c.$, and $B^{0*}\bar{B}^{0*}$. Decoherence effects are studied with the Partial Spontaneous Disentanglement model, which introduces a fraction $\zeta$ of $B^{0*}\bar{B}^{*0}$ pairs disentangled at production. The analysis exploits the decay times of both neutral B mesons, for which time-dependent probability density functions are derived and extended to include detector-resolution effects. The framework is first validated on Signal Monte Carlo samples, where one-dimensional fits to $\Sigma t$ successfully recover the expected decoherence values for both entangled and disentangled configurations. Fits to Generic Monte Carlo samples, which include realistic backgrounds and event compositions, reveal strong correlations between the decoherence parameter and flavour-tagging wrong-tag fractions, particularly in the $C=-1$ channels. The results from these fits show significant deviations from expected $\zeta$ values and large uncertainties. Pure Toy Monte Carlo studies confirm that the fitter behaves linearly with respect to the injected decoherence parameter and show only small biases consistent with those observed in the nominal fits, but too small to fully explain them. To address the limitations of the single fits, a two-dimensional analysis in $(\Delta t,\Sigma t)$ is developed. By exploiting the full time-dependent information, the two-dimensional fit significantly reduces the statistical uncertainty on the decoherence parameter from $\sim\mathcal{O}(10\%)$ to $\sim\mathcal{O}(4\%)$ and mitigates correlations with the flavour-tagging parameters. This work constitutes a proof of concept for future analyses on Belle data and demonstrates the potential of the $\Upsilon(5S)$ system for studying quantum entanglement and decoherence in neutral B mesons.

Jan 1, 20260 citations

In this work we study temporal quantum correlations, quantified by Leggett-Garg (LG) and LG-type inequalities, in the

B

and

K

meson systems. We use the tools of open quantum systems to incorporate the effect of decoherence which is quantified by a single phenomenological parameter. The effect of

CP

violation is also included in our analysis. We find that the LG inequality is violated for both

B

and

K

meson systems, the violation being most prominent in the case of

K

mesons and least for

{B}_{s}

system. Since the systems with no coherence do not violate LGI, incorporating decoherence is expected to decrease the extent of violation of LGI and is clearly brought out in our results. We show that the expression for the LG functions depends upon an additional term, apart from the experimentally measurable meson transition probabilities. This term vanishes in the limit of zero decoherence. On the other hand, the LG-type parameter can be directly expressed in terms of transition probabilities, making it a more appropriate observable for studying temporal quantum correlations in neutral meson systems.

Study of Quantum Decoherence in Neutral B Meson pairs produced at the

\Upsilon(5S)

Resonance

This thesis presents the development and validation of an analysis framework to study quantum decoherence in neutral B-meson pairs produced at the

\Upsilon(5S)

resonance, using Monte Carlo simulated data from the Belle experiment. Unlike the

\Upsilon(4S)

, the

\Upsilon(5S)

provides access to both antisymmetric (

C=-1

) and symmetric (

C=+1

) quantum states through the channels

B^0\bar{B}^0

B^{0*}\bar{B}^0+c.c.

, and

B^{0*}\bar{B}^{0*}

. Decoherence effects are studied with the Partial Spontaneous Disentanglement model, which introduces a fraction

\zeta

B^{0*}\bar{B}^{*0}

pairs disentangled at production. The analysis exploits the decay times of both neutral B mesons, for which time-dependent probability density functions are derived and extended to include detector-resolution effects. The framework is first validated on Signal Monte Carlo samples, where one-dimensional fits to

\Sigma t

successfully recover the expected decoherence values for both entangled and disentangled configurations. Fits to Generic Monte Carlo samples, which include realistic backgrounds and event compositions, reveal strong correlations between the decoherence parameter and flavour-tagging wrong-tag fractions, particularly in the

C=-1

channels. The results from these fits show significant deviations from expected

\zeta

values and large uncertainties. Pure Toy Monte Carlo studies confirm that the fitter behaves linearly with respect to the injected decoherence parameter and show only small biases consistent with those observed in the nominal fits, but too small to fully explain them. To address the limitations of the single fits, a two-dimensional analysis in

(\Delta t,\Sigma t)

is developed. By exploiting the full time-dependent information, the two-dimensional fit significantly reduces the statistical uncertainty on the decoherence parameter from

\sim\mathcal{O}(10\%)

\sim\mathcal{O}(4\%)

and mitigates correlations with the flavour-tagging parameters. This work constitutes a proof of concept for future analyses on Belle data and demonstrates the potential of the

\Upsilon(5S)

system for studying quantum entanglement and decoherence in neutral B mesons.