Mid-rapidity anti-baryon to baryon ratios in pp collisions at $\sqrt{s} = 0.9,\ 2.76\mbox{ and }7\mbox{ TeV}$ measured by ALICE

Abstract

The ratios of yields of anti-baryons to baryons probes the mechanisms of baryon-number transport. Results for p/p, / , + / − and + / − in pp collisions at √ s = 0.9, 2.76 and 7 TeV, measured with the ALICE detector at the LHC, are reported. Within the experimental uncertainties and ranges covered by our measurement, these ratios are independent of rapidity, transverse momentum and multiplicity for all measured energies. The results are compared to expectations from event generators, such as PYTHIA and HIJING/B, that are used to model the particle production in pp collisions. The energy dependence of p/p, / , + / − and + / − , reaching values compatible with unity for √ s = 7 TeV, complement the earlier p/p measurement of ALICE. These dependencies can be described by exchanges with the Regge-trajectory intercept of α J ≈ 0.5, which are suppressed with increasing rapidity interval y. Any significant contribution of an exchange not suppressed at large y (reached at LHC energies) is disfavoured.

Measurement of transverse energy at midrapidity in Pb-Pb collisions atsNN=2.76TeV

“…These assumptions are consistent with the data at high energies where positively and negatively charged hadrons are produced at similar rates and the antibaryon to baryon ratio is close to one [56,57]. Because the spectra [49] are only measured for five centrality bins, the contribution is interpolated from the neighboring centrality bins.…”

Production of light nuclei and anti-nuclei inppand Pb-Pb collisions at energies available at the CERN Large Hadron Collider

“…The applied correction factors are parametrized with the same function which was used for a similar study in Ref. [35]. FIG.…”

“…Following the approach described in Ref. [35], the correction for interaction of (anti-)nuclei with the detector material from GEANT3 was scaled to match the expected values from GEANT4. An alternative implementation to correct for this effect and the relevant uncertainties related to these corrections is discussed in Sec.…”

Production of (Anti-)(Hyper)nuclei in Pb–Pb Collisions Measured with ALICE at the LHC

“…The simulated particles were propagated through the detector using the GEANT3 transport code [14] and then processed through the same reconstruction chain as for the real data. Since the absorption of (anti-)(hyper)nuclei is not properly implemented in GEANT3, a correction based on the measured p (p) absorption [15] was applied in order to take into account the absorption of 3 Λ H ( 3 Λ H) and 3 He ( 3 He) in the material of the ALICE detector. In this approach, the 3 He and 3 Λ H were treated as states of three independent p (p) by means of a proper model, which was tested with deuterons.…”