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

Abstract

Abstract A search for CP violation in $$ {D}^0\to {K}_S^0{K}^{+}{\pi}^{-} $$ D 0

→

K S 0

K +

π −

and $$ {D}^0\to {K}_S^0{K}^{-}{\pi}^{+} $$

D 0

→

K S 0

K −

π +

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 $$ \sqrt{s} $$

s

= 13 TeV, amounting to approximately 950 thousand and 620 thousand signal candidates for the $$ {D}^0\to {K}_S^0{K}^{-}{\pi}^{+} $$

D 0

→

K S 0

K −

π +

and $$ {D}^0\to {K}_S^0{K}^{+}{\pi}^{-} $$

D 0

→

K S 0

K +

π −

modes, respectively. The method is validated using D0 → K−π+π−π+ and $$ {D}^0\to {K}_S^0{\pi}^{+}{\pi}^{-} $$

D 0

→

K S 0

π +

π −

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 $$ {D}^0\to {K}_S^0{K}^{-}{\pi}^{+} $$

D 0

→

K S 0

K −

π +

and the $$ {D}^0\to {K}_S^0{K}^{+}{\pi}^{-} $$

D 0

→

K S 0

K +

π −

decays, with p-values for the hypothesis of no CP violation of 70% and 66%, respectively.