Strange particle production in proton–proton collisions at $\sqrt{s}=0.9$ $\mbox {${\rm TeV}$}$ with ALICE at the LHC

Abstract

The production of mesons containing strange quarks (K 0 S , φ) and both singly and doubly strange baryons ( , , and − + + ) are measured at mid-rapidity in pp collisions at √ s = 0.9 TeV with the ALICE experiment at the LHC. The results are obtained from the analysis of about 250 k minimum bias events recorded in 2009. Measurements of yields (dN/dy) and transverse momentum spectra at mid-rapidity for inelastic pp collisions are presented. For mesons, we report yields ( dN/dy ) of 0.184 ± 0.002(stat.) ± 0.006(syst.) for K 0 S and 0.021 ± 0.004(stat.) ± 0.003(syst.) for φ. For baryons, we find dN/dy = 0.048 ± 0.001(stat.) ± 0.004(syst.) for , 0.047 ± 0.002(stat.) ± 0.005(syst.) for and 0.0101 ± 0.0020(stat.) ± 0.0009(syst.) for − + + . The results are also compared with predictions for identified particle spectra from QCD-inspired models and provide a baseline for comparisons with both future pp measurements at higher energies and heavy-ion collisions.

Measurement of V 0 production ratios in pp collisions at $ \sqrt {s} = 0.9 $ and 7 TeV

“…Excellent agreement is observed between results at both √ s = 0.9 and 7 TeV as well as with results from STAR at √ s = 0.2 TeV. The measured ratios are also consistent with results published by ALICE [2] and CMS [3].…”

Underlying Event measurements in pp collisions at $ \sqrt {s} = 0.9 $ and 7 TeV with the ALICE experiment at the LHC

“…Its high granularity and particle identification capabilities can be exploited for precise measurements of global event properties [18][19][20][21][22][23][24]. The central barrel covers the polar angle range 45 • −135 • (|η| < 1) and full azimuth.…”

“…We multiply the contamination estimate by a data-driven coefficient to take into account the low strangeness yield in the Monte Carlo compared to data [24]. The coefficient is derived from a fit of the discrepancy between data and Monte Carlo strangeness yields in the tails of the DCA XY distribution which are predominantly populated by secondaries.…”

“…Moreover, we have compared our assessment of the underestimation of strangeness yields with a direct measurement from the ALICE collaboration [24]. Based on the discrepancy between the two estimates, we assign a systematic uncertainty of 0-2.3% depending on the p T threshold and collision energy, see tables 5 and 6.…”

Tsallis Distribution Decorated with Log-Periodic Oscillation

“…The same formula re-emerged later to become known as the QCD-based Hagedorn formula [7]. It was used for the first time in [8] and became one of the standard phenomenological formulas for p T data analysis [9][10][11][12][13][14][15][16][17].…”