Search for the $C\!P$-violating strong decays $η\to π^+π^-$ and $η^\prime(958) \to π^+π^-$

Journal article

A search for the $C\!P$-violating strong decays $\eta \to \pi^+\pi^-$ and $\eta^\prime(958) \to \pi^+\pi^-$ has been performed using approximately $2.5 \times 10^{7}$ events of each of the decays $D^+ \to \pi^+\pi^+\pi^-$ and $D_s^+ \to \pi^+\pi^+\pi^-$, recorded by the LHCb experiment. The data set corresponds to an integrated luminosity of 3.0 fb$^{-1}$ of $pp$ collision data recorded during LHC Run 1 and 0.3 fb$^{-1}$ recorded in Run 2. No evidence is seen for $D^+_{(s)} \to \pi^+ \eta^{(\prime)}$ with $\eta^{(\prime)} \to \pi^+\pi^-$, and upper limits at 90% confidence level are set on the branching fractions, $\mathcal{B}(\eta \to \pi^+\pi^-) < 1.6 \times 10^{-5}$ and $\mathcal{B}(\eta^\prime \to \pi^+\pi^-) < 1.8 \times 10^{-5}$. The limit for the $\eta$ decay is comparable with the existing one, while that for the $\eta^\prime$ is a factor of three smaller than the previous limit.

Authors: Aaij, R; Adeva, B; Adinolfi, M; Cheung, S; Evans, T

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Elsevier
• Journal: Physics Letters B
• Volume: 764
• Pages: 233-240
• Publication date: 2016-11-23
• Acceptance date: 2016-11-17
• DOI: 10.1016/j.physletb.2016.11.032
• EISSN: 1873-2445
• ISSN: 0370-2693
• Keywords: hep-ex