Heavy-flavour hadronization in pp and heavy ion collisions at the LHC

2 Mar 2020, 09:00 → 3 Mar 2020, 18:10 Europe/Zurich

4/3-006 - TH Conference Room (CERN)

The LHC Collaborations reported measurements of the baryon-to-meson ratios for open charm and bottom hadrons in pp, p-Pb and, to some extent, Pb-Pb collisions at the LHC that challenge the present understanding of heavy-quark hadronization in hadronic collisions. The Lambda_c/D,  Xi_c/D and Lambda_b/B ratios at low momentum are larger than those measured in e+e– and ep collisions at LEP and HERA and predicted by event generators based on string fragmentation and tuned to describe the LEP and HERA data. The Lambda_c/D ratio in pp and p-Pb collisions is remarkably similar to the Lambda/K ratio and both are larger than the p/pi ratio. 

These findings show that the baryon-to-meson ratio depends on the collision system, highlighting the relevance of “long-distance” effects in heavy-quark hadronization. Various QCD mechanisms are recently being considered in the theory community to describe the observations, including colour reconnection, ropes, or statistical approaches. Such effects also have an impact on the measurement of the total heavy-quark production cross section and on the usage of D and B meson production measurements to constrain the PDFs in the proton and in the nucleus.
In nucleus-nucleus collisions, where a hot and dense quark-gluon plasma forms and collectively expands, the enhancement of baryon-to-meson ratios is predicted by theoretical models in which heavy quarks with low momentum hadronize by coalescence with light quarks from the plasma. The first measurements of Lambda_c production in nucleus-nucleus at the LHC (and at RHIC) hint at a larger ratio to D mesons, with respect to the case of pp collisions.
The goals of the proposed workshop are:

1. review and compare the results from the LHC experiments in various collision systems
2. review the status of hadronisation in pp and p-Pb collisions as described in event generators
3. discuss possible new measurements and theory developments
4. discuss the possible commonalities of the physics mechanisms in small and large hadronic collision systems as well as in the light- and heavy-flavour sectors.  

​VIDYO connection will be available.

For information relative to housing, access to CERN for those not holding a CERN card and laptop registration, please check http://lpcc.web.cern.ch/about

The workshop is co-sponsored by the STRONG 2020 project (EU Horizon 2020 grant 824093). 

Monday, 2 March

1 What can we learn about HQ diffusion from AA and pA?

Speaker: Hendrik van Hees (Goethe University Frankfurt)

cern-hq20.pdf

2 What can we learn about Heavy Flavour hadronization from pp, pA and AA @ LHC?

Speaker: Salvatore Plumari (University of Catania (Italy))

PLUMARI_Cern2020.pdf

3 Heavy Flavour in the Statistical Hadronization Model

Speaker: Anton Andronic (Westfaelische Wilhelms-Universitaet Muenster (DE))

cern20.pdf

4 Azimuthal anisotropies in heavy quark production in pp and PbPb, and PbPb onium production: ATLAS results

Speaker: Songkyo Lee (Iowa State University (US))

20200302_songkyo_HFH2020_v3.pdf

16:10 Coffee

5 Measurement of Lambda_c and Xi_c production in pp and p-Pb collisions with ALICE

Speaker: Pietro Antonioli (Universita e INFN, Bologna (IT))

Antonioli-20200302.pdf

6 Heavy Flavour production in pp and heavy ion collisions at LHCb

Speaker: Dr Benjamin Audurier (Centre national de la recherche scientifique)

Audurier_HF_hadronization.pdf

7 Wrap-up discussion

discussion points

18:30 Welcome drink

Salle des Pas perdue is just adjacent CERN's Main Auditorium, on the floor above the cafeteria

Tuesday, 3 March

8 Soft Heavy Flavour Production in PYTHIA

Speaker: Peter Skands (Monash University (AU))

20-HeavyFlavour.pdf

9 Soft Heavy Flavour Production in HERWIG

Speaker: Simon Platzer (University of Vienna (AT))

slides.pdf

10 Charm hadron production in pp and PbPb collisions - Theory

Speaker: Min He

M.He_CERN_HQ_Hadronization_Workshop_Mar.2020.pdf

10:25 Coffee

11 B_s, D_s, and strange and charm baryons in pp and PbPb with CMS

Speaker: Zhaozhong Shi (Massachusetts Inst. of Technology (US))

CERN HF Workshop Final Draft.pdf

12 Measurement of Lambda_c production in Pb-Pb collisions with ALICE

Speaker: Lucas Anne Vermunt (Utrecht University (NL))

HFHadroWorkshop_LVermunt.pdf

13 Measurement of D_s production in pp, pPb and PbPb collisions with ALICE

Speaker: Fabrizio Grosa (Politecnico di Torino (IT))

Ds_HadronisationWS2020_Grosa.pdf

12:25 Lunch break

14 ATLAS measurement of Ks0 and Lambda0 production in ttbar dileptonic events

Speaker: Sergio Calvente Lopez (Universidad Autonoma de Madrid (ES))

ATLAS_k0_Lambda_ttbar.pdf

15 ATLAS measurement of the relative Bc/B+ production cross section

Speaker: Konstantin Toms (University of New Mexico (US))

HFH2020_ktoms.pdf

16 X production in pp and PbPb, and heavy flavour hadron spectroscopy with CMS

Speaker: Alexis Pompili (Universita e INFN, Bari (IT))

HF-hadronization-pp-HI-CERN-Pompili-final-animated.pdf

17 Theoretical aspects of heavy quark exotica production in pp, pA and AA

Speaker: Antonio Polosa (Sapienza Universita e INFN, Roma I (IT))

ProductionX.pdf

16:00 Summary Discussion