HonexComb meeting #13

Tuesday 22 Feb 2022, 14:30 → 16:30 Europe/Zurich

53/R-044 (CERN)

Honexcomb #13

24 participants at peak

Georgios - light by light

Raph : How is the approval progressing in the collaboration ? No objection on the CMS side ; waiting for the ATLAS answer ; sharing intel…

Jacek : Could you elaborate on the 10% improvement in the combined measurement?

Sandor - Lambda c / D

Johanna : LHCb at 0.4, not consistent with slide 4… Peculiar rapidity dependence on slide 7… Jiayin : LHCb has new analysis going on, in pPb and PbPb, stay tuned…

Raph : Would it help to put the points at a more realistic pt when the bins are really large?

Jaebeom : comparison with models, slide 8, is color reconnection still in the game?

Jeremy : Lambda c in pp at 5 TeV from LHCb would really help, or even at 13 TeV. Slide 5 : the blue points are at the wrong energy.

Christian : Pythia, was discussed a bit in the open charm task force. Be careful about using color reconnection for cascades.

Florian - quarkonium feed-downs

Johanna and Cesar : have you tried to look at e+ e- ? Within a flavor, that could work…

Cesar : slide 4 from converted photons ? Yes.

Iwona : Plans for charmonia? Next report

Jaebeom : Consider the polarization ?
offline follow-up discussion: Jaebeom was mentioning the impact of polarization effects on cross-section model calculations. However, so far my derivation of feed-down fractions is completely based on experimental measurements which, hopefully, account for the uncertainty on an hypothetical polarized quarkonium production. I only refer to theory to support some assumptions when necessary.

Jeremy - Open charm

Johanna : Should provide d sigma / d y first, before to integrate

Slide 4 : How comes Alice and LHCb+Alice agree for the Lambda-c ? LHCb almost don’t contribute.

Cesar : Slide 4, which fragmentation functions ? In comes from the measurements here ; otherwise the ones from Pythia in the simulations.

Iwona : Timeline - after QM2022

1 News

Speakers: Alexander Philipp Kalweit (CERN), Christian Bierlich (Lund University (SE)), Giulia Manca (Universita` degli studi di Cagliari and INFN, Cagliari, IT), Iwona Grabowska-Bold (AGH University of Science and Technology (PL)), Jacek Tomasz Otwinowski (Institute of Nuclear Physics Polish Academy of Sciences (PL)), Jacopo Ghiglieri (Centre National de la Recherche Scientifique (FR)), Raphael Granier De Cassagnac (Centre National de la Recherche Scientifique (FR))

2022.02.22.HONEXCOMB.pdf

2 Light-by-Light scattering

Speaker: Georgios Krintiras (The University of Kansas (US))

Slides

3 Lambda-c / D comparison plots

Speaker: Sandor Lokos (Institute of Nuclear Physics Polish Academy of Sciences (PL))

Lc_D_ratio.pdf

Lc_D_ratio.pptx

Results on Lc / D ratio were presented from ALICE, LHCb, CMS, STAR

LHCb results pp and PbPb at 13 TeV are coming up this year, hopefully resolves seom disagreements between the data. ALICE already submitted such results. It would be good to compare these.

Rapidity and pT dependencies are intended to be understood via modelling. As a first approach Christian, Jacek and Sandor will consult on PYTHIA 8 and where they can get with that.

Concerns were raised about the rapidity dependence. This is the most visible disagreement between LHCb and other experiments (see slide 7).

 

4 Quarkonium feed-downs

Speaker: Florian Damas (LLR - Centre National de la Recherche Scientifique (FR))

feeddowns_honexcomb_22-02-2022.pdf

5 A word about the total charm cross section ?

Speakers: Jeremy Wilkinson (GSI - Helmholtzzentrum fur Schwerionenforschung GmbH (DE)), Jiayin Sun (Universita e INFN, Cagliari)

HonexComb_totalcharm_jwilkinson_22022022.pdf