Measurements of $${\Xi }{^-} $$ and $$\overline{\Xi }{^+} $$ production in proton–proton interactions at $$\sqrt{s_{NN}}$$ = 17.3 $$\hbox {Ge}\hbox {V}$$ in the NA61/SHINE experiment

Abstract

The production of $$\Xi (1321)^{-}$$ Ξ ( 1321 ) - and $$\overline{\Xi }(1321)^{+}$$ Ξ ¯ ( 1321 ) + hyperons in inelastic p+p interactions is studied in a fixed target experiment at a beam momentum of 158 $$\hbox {Ge}\hbox {V}\!/\!c$$ Ge / c . Double differential distributions in rapidity $${y}$$ y and transverse momentum $$p_{T}$$ p T are obtained from a sample of 33M inelastic events. They allow to extrapolate the spectra to full phase space and to determine the mean multiplicity of both $${\Xi }{^-} $$ Ξ - and $$\overline{\Xi }{^+} $$ Ξ ¯ + . The rapidity and transverse momentum spectra are compared to transport model predictions. The $${\Xi }{^-} $$ Ξ - mean multiplicity in inelastic p+p interactions at 158 $$\hbox {Ge}\hbox {V}\!/\!c$$ Ge / c is used to quantify the strangeness enhancement in A+A collisions at the same centre-of-mass energy per nucleon pair.

Highlights from NA61/SHINE

“…The results refer to primary Ξ − and Ξ + produced in strong and electromagnetic processes and are corrected for geometrical detector acceptance and reconstruction efficiency. This data was used to calculate the enhancement factors, , as a ratio of rapidity density for hyperons production in mid-rapidity in nucleus-nucleus collisions per the number of wounded nucleons divided by the corresponding value from p+p interactions [16] at given collision energy. The enhancement factors are presented in Figure 7 and the NA61/SHINE results on Ξ − and Ξ + production in p+p interactions created a new reference for the recalculation of the strangeness enhancement observed in the NA57 p+Be and A+A data.…”

“…The enhancement factors are presented in Figure 7 and the NA61/SHINE results on Ξ − and Ξ + production in p+p interactions created a new reference for the recalculation of the strangeness enhancement observed in the NA57 p+Be and A+A data. + production (right) in nucleus-nucleus interactions per number of wounded nucleons divided by the corresponding value for p+p interactions [16] This result is compared to data from the NA57 experiment at the SPS [17], the STAR experiment at the RHIC [18] and the ALICE experiment at the LHC [19].…”

Measurements of $${\Xi \left( 1530\right) ^{0}} $$ and $${\overline{\Xi }\left( 1530\right) ^{0}} $$ production in proton–proton interactions at $$\sqrt{s_{NN}}$$ = 17.3 $$\text{ GeV }$$ in the NA61/SHINE experiment

“…The rapidity densities (dn/dy) at mid-rapidity of (1530) 0 and (1530) 0 produced in inelastic p+p interactions at √ s N N = 17.3 GeV collisions can be compared with results from ALICE at CERN LHC measured at √ s N N = 7 TeV [2]. The ratios of (1530) to [11,12] at mid-rapidity in p+p interactions at 17.3 GeV and 7 TeV are shown in Table 4. The ratio of (1530) to at these two energies are similar: 0.294 ± 0.017 ± 0.047 at 17.3 GeV and 0.3241 ± 0.0053 +0.0325 0.0275 at 7 TeV, while the yields of (1530) 0 increase with collision energy by an order of magnitude from (2.75±0.18±0.58)×10 −4 at 17.3 GeV to (2.56±0.07 +0.40 −0.37 )×10 −3 at 7 TeV.…”

“…The new measurements by NA61/SHINE of (1530) 0 and (1530) 0 produced in inelastic p+p interactions at 158 GeV/c as well as previously obtained results for π + , π − , K + , K − , p, p, K * (892) 0 , , φ(1020), − and + (see Refs. [3,4,12,[17][18][19][20]) were compared to two versions of the Hadron Resonance Gas Model (HRG) using the software package THERMAL-FIST 1.3 of Ref. [21].…”

Fragmentation Functions for $Ξ^-/\barΞ^+$ Using Neural Networks

“…Earlier data are also available from MARKII [12] and TASSO [13,14] at somewhat smaller center-of-mass energies. In recent years, also data for Ξ − -production in pp and pp collisions have been published, covering centerof-mass energies from √ s = 17.3 GeV at NA61/SHINE [15], √ s = 200 GeV at STAR [16,17], 1.96 TeV at CDF [18], and up to 7 and 13 TeV at CMS [19,20] and ALICE [21][22][23]. The relevant energy scale in these collider experiments is the transverse momentum of the produced hadron which is, however, rather low and does not reach values above 10 GeV.…”