The first measurement at midrapidity (|y| < 0.5) of the production yield of the strange-charm baryons Ξ+ c and Ξ0 c as a function of transverse momentum (pT) in dif- ferent charged-particle multiplicity classes in proton-proton collisions at √s = 13 TeV with the ALICE experiment at the LHC is reported. The Ξ+ c baryon is reconstructed via the Ξ+ c → Ξ−π+π+ decay channel in the range 4 < pT < 12 GeV/c, while the Ξ0 c baryon is reconstructed via both the Ξ0 c → Ξ−π+ and Ξ0 c → Ξ−e+νe decay channels in the range 2 < pT < 12 GeV/c. The baryon-to-meson (Ξ0,+ c /D0) and the baryon-to-baryon (Ξ0,+ c /Λ+ c ) production yield ratios show no significant dependence on multiplicity. In addition, the observed yield ratios are not described by theoretical predictions that model charm-quark fragmentation based on measurements at e+e− and e−p colliders, indicating differences in the charm-baryon production mechanism in pp collisions. A comparison with different event generators and tunings, including different modelling of the hadronisation process, is also discussed. Moreover, the branching-fraction ratio of BR(Ξ0 c → Ξ−e+νe)/BR(Ξ0 c → Ξ−π+) is measured as 0.825 ± 0.094 (stat.) ± 0.081 (syst.). This value supersedes the previous ALICE measurement, improving the statistical precision by a factor of 1.6.
Multiplicity dependence of Csic+ and Csic0 production in pp collisions at sqrt(s)=13 TeV
Cortese, P.;Jacazio, N.;Ramello, L.;Sitta, M.;
2025-01-01
Abstract
The first measurement at midrapidity (|y| < 0.5) of the production yield of the strange-charm baryons Ξ+ c and Ξ0 c as a function of transverse momentum (pT) in dif- ferent charged-particle multiplicity classes in proton-proton collisions at √s = 13 TeV with the ALICE experiment at the LHC is reported. The Ξ+ c baryon is reconstructed via the Ξ+ c → Ξ−π+π+ decay channel in the range 4 < pT < 12 GeV/c, while the Ξ0 c baryon is reconstructed via both the Ξ0 c → Ξ−π+ and Ξ0 c → Ξ−e+νe decay channels in the range 2 < pT < 12 GeV/c. The baryon-to-meson (Ξ0,+ c /D0) and the baryon-to-baryon (Ξ0,+ c /Λ+ c ) production yield ratios show no significant dependence on multiplicity. In addition, the observed yield ratios are not described by theoretical predictions that model charm-quark fragmentation based on measurements at e+e− and e−p colliders, indicating differences in the charm-baryon production mechanism in pp collisions. A comparison with different event generators and tunings, including different modelling of the hadronisation process, is also discussed. Moreover, the branching-fraction ratio of BR(Ξ0 c → Ξ−e+νe)/BR(Ξ0 c → Ξ−π+) is measured as 0.825 ± 0.094 (stat.) ± 0.081 (syst.). This value supersedes the previous ALICE measurement, improving the statistical precision by a factor of 1.6.| File | Dimensione | Formato | |
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