Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:2405.16525 · Scientific Reports

Entanglement and Bell inequality violation in vector diboson systems produced in decays of spin-0 particles

Alexander Bernal, Paweł Caban, Jakub Rembieliński

Published Jul 2, 2025• 18 citations
arXivHTMLPDF

Abstract

We discuss entanglement and the violation of the Collins-Gisin-Linden-Massar-Popescu (CGLMP) inequality in a system of two vector bosons produced in the decay of a spin-0 particle. We assume the most general CPT conserving, Lorentz- invariant coupling of the spin-0 particle with the daughter bosons. We compute the most general two-boson density matrix obtained by averaging over kinematical configurations with an appropriate probability distribution (which can be obtained when both bosons subsequently decay into fermion-antifermion). We show that the two-boson state is entangled and violates the CGLMP inequality for all values of the (anomalous) coupling constants and that in this case the state is entangled iff it can violate the CGLMP inequality. As an exemplary process of this kind we use the decay [Formula: see text] with anomalous coupling.

DOI
10.1038/s41598-025-07747-3

Related papers

Entanglement and Bell inequalities violation in $$H\rightarrow ZZ$$ with anomalous coupling

Alexander Bernal, Paweł Caban, Jakub Rembieliński

Abstract We discuss entanglement and violation of Bell-type inequalities for a system of two Z bosons produced in Higgs decays. We take into account beyond the Standard Model (anomalous) coupling between H and daughter bosons but we limit ourselves to an overall scalar ZZ state (we exclude the possibility that H contains a pseudo-scalar component). In particular we consider the case when each Z decays further into fermion-antifermion pair. We find that the ZZ state is entangled and violates the CGLMP inequality for all values of the (anomalous) coupling constant. We also discuss the impact of a background on these results. The methods we develop are completely general, since they can be extrapolated to any scalar particle decaying into two spin-1 particles of different masses. Moreover, the violation of the CGLMP inequality in the final state is theoretically ensured for any value of the couplings.

arXiv:2307.13496•The European Physical Journal C•Nov 17, 2023•46 citations

Bell-type inequalities for systems of relativistic vector bosons

Alan J. Barr, Paweł Caban, Jakub Rembieliński

We perform a detailed analysis of the possible violation of various Bell-type inequalities for systems of vector boson-antiboson pairs. Considering the general case of an overall scalar state of the bipartite system, we identify two distinct classes of such states, and determine the joint probabilities of spin measurement outcomes for each them. We calculate the expectation values of the CHSH, Mermin and CGLMP inequalities and find that while the generalised CHSH inequality is not expected to be violated for any of the scalar states, in the case of the Mermin and CGLMP inequalities the situation is different – these inequalities can be violated in certain scalar states while they cannot be violated in others. Moreover, the degree of violation depends on the relative speed of the two particles.

arXiv:2204.11063•Quantum•Jul 27, 2023•39 citations

Gisin’s theorem for two d -dimensional systems based on the Collins-Gisin-Linden-Masser-Popescu inequality

Jing‐Ling Chen, Dong-Ling Deng, Ming-Guang Hu

In this Rapid Communication, we show analytically that all pure entangled states of two $d$-dimensional systems (qudits) violate the Collins-Gisin-Linden-Masser-Popescu (CGLMP) inequality. This property was pointed out by Gisin in the qubit case and then generalized by Gisin-Peres and Popescu-Rohrlich to the qudit case based on the Clauser-Horne-Shimony-Holt (CHSH) inequality. We report the Gisin's theorem for two qudits by making use of the CGLMP inequality.

arXiv:0802.0125•Physical Review A•Jun 17, 2008•15 citations

Testing Bell inequalities in Higgs boson decays

Alan J. Barr

Higgs boson decays produce pairs of W bosons in a maximally entangled state, the spins of which can be expected to violate Bell inequalities. We show that the spin density matrix of the W± pair may be reconstructed experimentally from the directions of the charged lepton decay products, and from it the expectation values of various Bell operators determined. Numerical simulations of H→WW⁎ decays indicate that violation of a generalised CHSH inequality is unlikely to be measurable, however the CGLMP inequality is near-maximally violated. Experimental Bell tests could be performed at a variety of colliders and in different production channels. If reconstruction effects and backgrounds can be controlled then statistically significant violations could be observable even with datasets comparable to those already collected at the LHC.

arXiv:2106.01377•Physics Letters B•Jan 4, 2022•105 citations

Entanglement and Bell inequality violation in $B\to \it{ΦΦ}$ decays

Emidio Gabrielli A, Luca Marzola

The decays of the $B$ meson into vector mesons, observed at the LHCb experiment, provide an ideal laboratory to investigate particle physics phenomena with quantum information theory methods. In this article, we focus on the decays yielding a pair of $\itΦ$ mesons to investigate the presence of entanglement in the spin correlations of the system and quantify the amount of Bell inequality violation it entails. Our results show that the present LHCb data allows access to entanglement and to the Bell inequality violation with a significance exceeding the 5$σ$ threshold in both the cases. This demonstrates that the strong and electroweak interactions responsible for the $B$ meson decay act as a source of entanglement and the quantum mechanics nature of high-energy phenomena. Particular attention is paid to the assessment of loopholes: deficiencies in the experimental setup which could invalidate the results of the Bell test.

arXiv:2408.05010•Aug 9, 2024•0 citations

Entanglement and Bell Inequality Violation in B → ϕϕ Decays

Emidio Gabrielli A, Luca Marzola

The decays of the B meson into vector mesons, observed during the LHCb experiment, provide an ideal laboratory to investigate particle physics phenomena with quantum information theory methods. In this article, we focus on the decays yielding a pair of ϕ mesons to investigate the presence of entanglement in the spin correlations of the system and quantify the amount of Bell inequality violation it entails. Our results show that the present LHCb data allow access to entanglement and to the Bell inequality violation with a significance exceeding the 5σ threshold in both the cases. This demonstrates that the strong and electroweak interactions responsible for the B meson decay act as a source of entanglement and the quantum mechanics nature of high-energy phenomena. Particular attention is paid to the assessment of loopholes: deficiencies in the experimental setup which could invalidate the results of the Bell test.

Symmetry•Aug 13, 2024•15 citations
We discuss entanglement and the violation of the Collins-Gisin-Linden-Massar-Popescu (CGLMP) inequality in a system of two vector bosons produced in the decay of a spin-0 particle. We assume the most general CPT conserving, Lorentz- invariant coupling of the spin-0 particle with the daughter bosons. We compute the most general two-boson density matrix obtained by averaging over kinematical configurations with an appropriate probability distribution (which can be obtained when both bosons subsequently decay into fermion-antifermion). We show that the two-boson state is entangled and violates the CGLMP inequality for all values of the (anomalous) coupling constants and that in this case the state is entangled iff it can violate the CGLMP inequality. As an exemplary process of this kind we use the decay [Formula: see text] with anomalous coupling.
Entanglement and Bell inequalities violation in H→ZZH\rightarrow ZZH→ZZ with anomalous coupling
Abstract We discuss entanglement and violation of Bell-type inequalities for a system of two Z bosons produced in Higgs decays. We take into account beyond the Standard Model (anomalous) coupling between H and daughter bosons but we limit ourselves to an overall scalar ZZ state (we exclude the possibility that H contains a pseudo-scalar component). In particular we consider the case when each Z decays further into fermion-antifermion pair. We find that the ZZ state is entangled and violates the CGLMP inequality for all values of the (anomalous) coupling constant. We also discuss the impact of a background on these results. The methods we develop are completely general, since they can be extrapolated to any scalar particle decaying into two spin-1 particles of different masses. Moreover, the violation of the CGLMP inequality in the final state is theoretically ensured for any value of the couplings.
We perform a detailed analysis of the possible violation of various Bell-type inequalities for systems of vector boson-antiboson pairs. Considering the general case of an overall scalar state of the bipartite system, we identify two distinct classes of such states, and determine the joint probabilities of spin measurement outcomes for each them. We calculate the expectation values of the CHSH, Mermin and CGLMP inequalities and find that while the generalised CHSH inequality is not expected to be violated for any of the scalar states, in the case of the Mermin and CGLMP inequalities the situation is different – these inequalities can be violated in certain scalar states while they cannot be violated in others. Moreover, the degree of violation depends on the relative speed of the two particles.
In this Rapid Communication, we show analytically that all pure entangled states of two ddd-dimensional systems (qudits) violate the Collins-Gisin-Linden-Masser-Popescu (CGLMP) inequality. This property was pointed out by Gisin in the qubit case and then generalized by Gisin-Peres and Popescu-Rohrlich to the qudit case based on the Clauser-Horne-Shimony-Holt (CHSH) inequality. We report the Gisin's theorem for two qudits by making use of the CGLMP inequality.
Higgs boson decays produce pairs of W bosons in a maximally entangled state, the spins of which can be expected to violate Bell inequalities. We show that the spin density matrix of the W± pair may be reconstructed experimentally from the directions of the charged lepton decay products, and from it the expectation values of various Bell operators determined. Numerical simulations of H→WW⁎ decays indicate that violation of a generalised CHSH inequality is unlikely to be measurable, however the CGLMP inequality is near-maximally violated. Experimental Bell tests could be performed at a variety of colliders and in different production channels. If reconstruction effects and backgrounds can be controlled then statistically significant violations could be observable even with datasets comparable to those already collected at the LHC.
Entanglement and Bell inequality violation in B→ΦΦB\to \it{ΦΦ}B→ΦΦ decays
The decays of the BBB meson into vector mesons, observed at the LHCb experiment, provide an ideal laboratory to investigate particle physics phenomena with quantum information theory methods. In this article, we focus on the decays yielding a pair of Φ\itΦΦ mesons to investigate the presence of entanglement in the spin correlations of the system and quantify the amount of Bell inequality violation it entails. Our results show that the present LHCb data allows access to entanglement and to the Bell inequality violation with a significance exceeding the 5σσσ threshold in both the cases. This demonstrates that the strong and electroweak interactions responsible for the BBB meson decay act as a source of entanglement and the quantum mechanics nature of high-energy phenomena. Particular attention is paid to the assessment of loopholes: deficiencies in the experimental setup which could invalidate the results of the Bell test.
The decays of the B meson into vector mesons, observed during the LHCb experiment, provide an ideal laboratory to investigate particle physics phenomena with quantum information theory methods. In this article, we focus on the decays yielding a pair of ϕ mesons to investigate the presence of entanglement in the spin correlations of the system and quantify the amount of Bell inequality violation it entails. Our results show that the present LHCb data allow access to entanglement and to the Bell inequality violation with a significance exceeding the 5σ threshold in both the cases. This demonstrates that the strong and electroweak interactions responsible for the B meson decay act as a source of entanglement and the quantum mechanics nature of high-energy phenomena. Particular attention is paid to the assessment of loopholes: deficiencies in the experimental setup which could invalidate the results of the Bell test.