# Publications by Neville Harnew

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

Physics Letters B Elsevier 764 (2016) 233-240

R Aaij, B Adeva, M Adinolfi, S-F Cheung, T Evans, P Gandini, BRG Cazon, T Hadavizadeh, N Harnew, D Hill, N Hussain, J Jalocha, M John, O Lupton, S Malde, A Nandi, W Qian, A Rollings, S Stevenson, S Topp-Joergensen, G Veneziano, G Wilkinson

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, $\mathcal{B}(\eta \to \pi^+\pi^-) &lt; 1.6 \times 10^{-5}$ and $\mathcal{B}(\eta^\prime \to \pi^+\pi^-) &lt; 1.8 \times 10^{-5}$. 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.

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