Measurement of $phi(1020)$ Meson Production in Fixed-Target $ptext{Ne}$ Collisions at $sqrt{s_{NN}} = 68.5~text{GeV}$

The first measurement of $phi(1020)$ meson production in fixed-target $ptext{Ne}$ collisions at $sqrt{s_{NN}} = 68.5~text{GeV}$ is presented. The $phi(1020)$ mesons are reconstructed in their $K^+K^-$ decay in a data sample consisting of proton collisions on neon nuclei at rest, corresponding to an integrated luminosity of $21.7 pm 1.4~text{nb}^{-1}$, collected by the LHCb detector at CERN. The $phi(1020)$ production cross-section in the centre-of-mass rapidity range of $-1.8 < y^ast < 0$ and transverse momentum range of $800 < p_T < 6500~text{MeV}/c$ is found to be [sigma = 182.7 pm 2.7~text{(stat.)} pm 14.1~text{(syst.)}~mutext{b/nucleon}.] A double-differential measurement of the cross-section is also provided in four regions of rapidity and six regions of transverse momentum of the $phi(1020)$ meson and compared with the predictions from Pythia and EPOS4, which are found to underestimate the experimental values.