K*(892)+production in proton-proton collisions atEbeam=3.5GeV

Abstract

We present results on the K * (892) + production in proton-proton collisions at a beam energy of E = 3.5 GeV, which is hitherto the lowest energy at which this mesonic resonance has been observed in nucleon-nucleon reactions. The data are interpreted within a two-channel model that includes the 3-body production of K * (892) + associated with the Λ-or Σ-hyperon. The relative contributions of both channels are estimated. Besides the total cross section σ(p + p → K * (892) + + X) = 9.5 ± 0.9 +1.1 −0.9 ± 0.7 µb, that adds a new data point to the excitation function of the K * (892) + production in the region of low excess energy, transverse momenta and angular spectra are extracted and compared with the predictions of the two-channel model. The spin characteristics of K * (892) + are discussed as well in terms of the spin-alignment.

Surprises for the Chemical Freeze-out Lines from the New Data in $p$+$p$ and $A$+$A$ Collisions

“…For the first time, the amount of p+p data was enough to perform the analysis of hadron production within thermal model at energies of √ s N N < 20 GeV, see [1,2]. The new p+p data of the NA61/SHINE and HADES collaborations at √ s N N = 3.2-17.3 GeV [3][4][5][6], the new A+A data of HADES, and the updated data of the NA49 Collaboration at √ s N N = 2.2-17.3 GeV were used for this purpose [1,7,8]. The result is very surprising, see Fig.…”