Search for CP violation in the phase space of D0 → KS0K±π∓ decays with the energy test

Lesya Shchutska, Olivier Schneider, Guido Haefeli, Frédéric Blanc, Tatsuya Nakada, Elena Graverini, Renato Quagliani, Aravindhan Venkateswaran, Luis Miguel Garcia Martin, Vitalii Lisovskyi, Veronica Sølund Kirsebom, Elisabeth Maria Niel, Ettore Zaffaroni, Dimitrios Kaminaris, Donal Patrick Hill, Sebastian Schulte, Surapat Ek-In, Sara Celani, Serhii Cholak
2024

Abstract

A search for CP violation in D-0 -> (KSK+)-K-0 pi(-) and D-0 -> (KSK-)-K-0 pi(+) decays is reported. The search is performed using an unbinned model-independent method known as the energy test that probes local CP violation in the phase space of the decays. The data analysed correspond to an integrated luminosity of 5.4 fb(-1) collected in proton-proton collisions by the LHCb experiment at a centre-of-mass energy of root s = 13TeV, amounting to approximately 950 thousand and 620 thousand signal candidates for the D-0 -> (KSK-)-K-0 pi(+) and D-0 -> (KSK+)-K-0 pi(-) modes, respectively. The method is validated using D-0 -> K-pi(+)pi(-)pi(+) and D-0 -> K-S(0)pi(+)pi(-) decays, where CP-violating effects are expected to be negligible, and using background-enhanced regions of the signal decays. The results are consistent with CP symmetry in both the D-0 -> (KSK-)-K-0 pi(+) and the D-0 -> (KSK+)-K-0 pi(-) decays, with p-values for the hypothesis of no CP violation of 70% and 66%, respectively.

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