Two-pion Bose-Einstein correlations inppcollisions ats=900  GeV

Abstract

We report on the measurement of two-pion correlation functions from pp collisions at ffiffi ffi s p ¼ 900 GeV performed by the ALICE experiment at the Large Hadron Collider. Our analysis shows an increase of the Hanbury Brown-Twiss radius with increasing event multiplicity, in line with other measurements done in particle-and nuclear collisions. Conversely, the strong decrease of the radius with increasing transverse momentum, as observed at the Relativistic Heavy Ion Collider and at Tevatron, is not manifest in our data.

Charged kaon femtoscopic correlations inppcollisions ats=7 TeV

“…4 show an increase with multiplicity in agreement with the radii, at 900 GeV [8] and 7 TeV [9], and the K 0 s K 0 s radii [10], as was observed for correlations in heavy-ion collisions [22]. These radii also decrease with increasing m T for the large multiplicity bins N ch (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) and N ch ð>22Þ.…”

“…For each class of events, we calculated the charged-particle pseudorapidity density dN ch =d corrected for the detection efficiency obtained with Monte Carlo. The considered event multiplicity ranges (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11), (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22), >22 correspond to mean charged-particle densities, dN ch =d, of 3.2, 8.1, and 17.2, respectively, with systematic uncertainties of $5%.…”

“…(1). The same method was used to model the baseline for the ALICE correlation studies in 0.9 [8] In order to estimate the systematic error from the choice of baseline functional form, we repeated the fitting procedure using the baseline fitted with Eqs. (3) and (4).…”

“…The ALICE Collaboration has already studied two-pion correlation radii in pp collisions at 900 GeV [8] and 7 TeV [9] and K 0 s K 0 s correlation radii in pp collisions at 7 TeV [10]. Two-pion Bose-Einstein correlations in pp collisions at ffiffi ffi s p ¼ 900 GeV and 7 TeV have been successfully described within the EPOS þ hydro model [11].…”

Multipion Bose-Einstein correlations inpp,p-Pb, and Pb-Pb collisions at energies available at the CERN Large Hadron Collider

“…The low-multiplicity events produced in pp and p-Pb collisions contain a non-negligible nonfemtoscopic background arising from minijets [30][31][32]. We reduce this background by retaining only high-multiplicity events in pp and p-Pb.…”