Measurement of heavy-flavour production in proton–proton collisions at with ALICE

Abstract

The measurement of the heavy-flavour production cross sections in pp collisions at the LHC will allow to test perturbative QCD calculations in a new energy domain. Moreover, within the physics program of the ALICE experiment, it will provide the reference for the study of medium effects in Pb-Pb collisions, where heavy quarks are regarded as sensitive probes of parton-medium interaction dynamics. We present the status and first preliminary results of charm and beauty production measurements with the ALICE experiment, using hadronic D meson decays and semi-leptonic D and B meson decays, including the first cross section measurement of muons from heavy flavour decays at forward rapidity. We also describe the preliminary cross section measurement for J/ψ production, obtained using the di-electron decay channel at central rapidity and the di-muon decay channel at forward rapidity.

Testing pQCD and AdS/CFT energy loss at RHIC and LHC

“…In Fig. 2 (a) we again see excellent agreement between the WHDG predictions of D meson suppression and the preliminary ALICE data [14] within the stated uncertainties. We provide for future reference WHDG predictions at √ s = 2.71 ATeV of B meson suppression in Fig.…”

“…At RHIC kinematics, no energy loss calculation provided a consistent picture of the multiple observables reported [2]. In particular, constraining pQCD-based calculations to π 0 suppression led to a qualitative underprediction of predictions from an AdS/CFT drag model [18] and constrained R D AA (p T ) and R π 0 AA (p T ) predictions from WHDG [3,2] compared to preliminary ALICE data [14] the v π 0 2 (p T 9 GeV/c) [19] and a quantitative underprediction of non-photonic electron suppression [3]. However, constrained to RHIC data, we find the pQCD-based WHDG energy loss calculation qualitatively describes the light hadron suppression and quantitatively describes the azimuthal anisotropy and heavy meson suppression at LHC, using no free parameters.…”

“…The three AdS/CFT drag curves shown explore part of the possible parameter space associated with linking QCD parameters to those in N = 4 SYM [5]. Clearly the drag predictions quantitatively overpredict the suppression of D mesons compared to the preliminary ALICE data [14]; however, due to the large uncertainties in that data, the theoretical calculation cannot currently be claimed to be falsified. Future distinguishing measurements include very different p T -dependencies for B meson suppression and for the double ratio of R D AA (p T )/R B AA (p T ).…”

“…FIGURE 2. (a) R DAA (p T ) predictions from an AdS/CFT drag model[18] and constrained R D AA (p T ) and R π 0 AA (p T ) predictions from WHDG[3,2] compared to preliminary ALICE data[14] at √ s = 2.76 ATeV and 0-20% centrality at LHC. Constrained (b) R B AA (p T ) and (c) R D AA (p T )/R B AA (p T ) predictions from WHDG and AdS/CFT drag models at √ s = 2.76 ATeV and 0-20% centrality at LHC.…”

Transport properties of the hot quark-gluon plasma

“…In figure 2 it is shown by solid line the prediction of the T-matrix approach while the dashed line show the result if one discard the coalescence mechanism and assume an hadronization only by parton fragmentation. Predictions for at the LHC appears to be also quite succesfull showing a fairly good agreement with eralier results from the ALICE Collaboration [21,22].…”