Speaker
Description
NA61/SHINE is a multi-purpose, fixed-target hadron spectrometer at the CERN SPS. Its research program includes studies of strong interactions as well as reference measurements for neutrino and cosmic-ray physics. A significant advantage of NA61/SHINE over collider experiments is its extended coverage of phase space available for particle production. This includes the entire projectile hemisphere of the collision, with no low-$p_T$ cut-off.
The energy and system-size dependence of strangeness production plays an essential role in studies of the transition from confined to deconfined matter. At the same time, resonance production is a key observable to study the dynamics of colliding systems at high density. With its zero net strangeness and its valence structure composed predominantly of $s$ and $\bar{s}$ valence quarks, the $\phi$(1020) meson will not be sensitive to strangeness-related effects in a purely hadronic scenario, but will behave like a doubly-strange particle in a partonic system. On the other hand, the $K^*$(892)$^0$ meson brings information on the time evolution of the hadronic phase, with the $K^*$(892)$^0$ to charged kaon production ratio allowing to estimate the time between chemical and kinetic freeze-outs.
This talk presents the first-ever results on $\phi$(1020) and $K^*$(892)$^0$ meson production in intermediate-size systems at the CERN SPS, that is, central Ar+Sc collisions at beam momenta of 40$A$, 75$A$, and 150$A$ GeV/$c$ ($\sqrt{s_{NN}}$ = 8.8, 11.9, and 16.8 GeV, respectively). The presented results include transverse momentum and transverse mass spectra, double-differential rapidity-$p_T$ distributions, $p_T$-integrated rapidity spectra, mean multiplicities, and particle ratios. These are compared to data on Pb+Pb and $p$+$p$ collisions. The discussion of open and hidden strangeness production enhancement, as well as the time between freeze-outs and rescattering is included in the talk. We also show the comparison with several microscopic models, demonstrating their overall failure in describing these new measurements.
| Category | Experiment |
|---|---|
| Collaboration (if applicable) | NA61/SHINE |
