Browsing Department of Electronics, Computing & Maths by Authors
Charged-particle pseudorapidity density at mid-rapidity in p–Pb collisions at √sNN = 8.16 TeVAcharya, S.; Acosta, F.-T.; Adamová, D.; Adhya, S. P.; Adler, A.; Adolfsson, J.; Aggarwal, M. M.; Rinella, G. Aglieri; Agnello, M.; Ahammed, Z.; et al. (Springer Science, 2019-04-04)The pseudorapidity density of charged particles, dNch/dη, in p–Pb collisions has been measured at a centreof-mass energy per nucleon–nucleon pair of √sNN = 8.16 TeV at mid-seudorapidity for non-single-diffractive events. The results cover 3.6 units of pseudorapidity, |η| < 1.8. The dNch/dη value is 19.1 ± 0.7 at |η| < 0.5. This quantity divided by Npart /2 is 4.73±0.20, where Npart is the average number of participating nucleons, is 9.5% higher than the corresponding value for p–Pb collisions at √sNN = 5.02 TeV. Measurements are compared with models based on different mechanisms for particle production. All models agree within uncertainties with data in the Pb-going side, while HIJING overestimates, showing a symmetric behaviour, and EPOS underestimates the p-going side of the dNch/dη distribution. Saturation-based models reproduce the distributions well for η > −1.3. The dNch/dη is also measured for different centrality estimators, based both on the chargedparticle multiplicity and on the energy deposited in the ZeroDegree Calorimeters. A study of the implications of the large multiplicity fluctuations due to the small number of participants for systems like p–Pb in the centrality calculation for multiplicity-based estimators is discussed, demonstrating the advantages of determining the centrality with energy deposited near beam rapidity.
Measuring K0sK± interactions using pp collisions at √s=7 TeVBoca, G.; Bock, F.; Bogdanov, A.; Boldizsár, L.; Bolozdynya, A.; Bombara, M.; Bonomi, G.; Bonora, M.; Borel, H.; Borissov, A.; et al. (Elsevier, 2019-03-10)We present the first measurements of femtoscopic correlations between the KS0 and K± particles in pp collisions at √s=7 TeV measured by the ALICE experiment. The observed femtoscopic correlations are consistent with final-state interactions proceeding solely via the a0(980) resonance. The extracted kaon source radius and correlation strength parameters for KS0K− are found to be equal within the experimental uncertainties to those for KS0K+. Results of the present study are compared with those from identical-kaon femtoscopic studies also performed with pp collisions at √s=7 TeV by ALICE and with a KS0K± measurement in Pb–Pb collisions at √sNN=2.76 TeV. Combined with the Pb–Pb results, our pp analysis is found to be compatible with the interpretation of the a0(980) having a tetraquark structure instead of that of a diquark.