Lc production in pp and pPb collisions with ALICE at the LHC

Submission Date: 
27/12/2017
Article Information
Submission Form
System: 
p-p
System: 
p-Pb
Energy: 
5.02 TeV
Energy: 
7 TeV
Abstract Plain Text: 

THIS IS A PRELIMINARY ABSTRACT: The paper will describe the results on the Lc cross-section in pp collisions at 7 TeV and pPb collisions at 5 TeV measured by ALICE at the LHC. Three decay channels will be presented (Lc --> pKpi, Lc --> K0sp, Lc --> enuL), and three different analysis approaches will be described.

The pt-differential production cross section of the prompt Lc+ charmed baryon was measured with the ALICE detector at the
Large Hadron Collider (LHC) in pp collisions at $\sqrt{s} = 7$ TeV and in pPb collisions at $\sqrt{s_{NN}} = 5.02$ TeV at midrapidity.
The Lc+ (and charge conjugate) was reconstructed in the hadronic decay modes Lc --> pKpi Lc --> pK0s and in the semileptonic
channel Lc --> enuL (and charge conjugates). The integrated luminosity of the data samples corresponds to L = 4.8 and 5.9 nb-1
in pp collisions in the hadronic and semileptonic channel respectively, and
L = 47.8 ub-1 in pPb collisions.
Different analysis techniques were used to measure the Lc+ cross section in the two systems, from which the Lc+/D0 ratio and the first measurement at the LHC of the Lc+ nuclear modification factor RpPb were derived.
The measured values of the Lc+/D0 ratio, which is sensitive to the c-quark hadronisation mechanism, and
in particular to the production of baryons, are $0.546 \pm 0.061 \pm \substack{ +0.164\\ -0.165} $ in \pp and $0.599 \pm 0.060 \substack{ +0.151\\ -0.082}$ in pPb collisions. The results are higher than what previous experiments measured at different colliding
systems, energies, rapidity and \pt intervals, where othere processes were involved, and where the Lc+ production modes may differ. The RpPb is found to be consistent with unity and with that of D mesons
within the uncertainties. The results are presented detailing the analysis methodologies, the systematic uncertainties, and are compared with the results of perturbative Quantum Chromodynamics calculations and Monte Carlo event generators.