Status of Xic0 analysis using semileptonic decay channel in p+Pb collisions Nov 16th 2019 Jeongsu Bok (Inha University) Motivation • Heavy quarks are • sensitive probes to study the Quark-Gluon Plasma in heavy-ion coll isions. • Due to their large masses, they are formed in initial hard scattering of parton before the timescale of QGP formation • àproduced early in the collision, live long enough to sample QGP • experience the whole system evolution • Baryon containing Heavy Quark • Charm-baryon measurements provide unique insight into hadroniz ation processes • Baryon-to-Meson ratio is expected to be higher in p+Pb and Pb+Pb 11/16/19 2 Charmed baryon-to-meson ratio • Charmed baryon-to-meson ratio in p+p and p+Pb higher tha n than model calculations 11/16/19 3 0 0 �c / D • Phys. Lett. B. 781 (2018) 8–19 • Theories underestimate it 11/16/19 4 Charmed baryon-to-meson ratio in Pb+Pb • Enhancement in Pb+Pb • Compatible with models that include recombination 11/16/19 5 Charmed baryon-to-meson ratio in terms of multiplicity • Increase from low to high multiplicity • ratio in high multiplicity in pp comparable Pb-Pb • àrecombination already saturated in p+p? 11/16/19 6 0 + �c (�c ) • Charm hadronization not fully understood • à we need more result with different channel such as �c • Possibility to be hadronized via coalescence in QGP? • Strange enhancement? • Multiplicity dependence? 11/16/19 7 0 Studying �c using semi-leptonic decay • Analysis procedure • Reconstruct �- Hadronic decay channel: 0 • Reconstruct electron �c à π+ Ξ- → π+ π- Λ → π+ π- p π- • Subtract WS background 0 • Unfold �c pT spectra • Dataset • p+Pb 5.02 TeV • Using LHC16q (32 runs) (LHC16t 4 runs) • MC : LHC17d2b_fast_new 11/16/19 8 Backup : p+Pb plots • �- Mass p+p 13 TeV LHC16l 11/16/19 9 Backup : p+Pb plots • Nsigma (TOF), nsigma (TPC) p+Pb 5 TeV • p+p 13 TeV LHC16l 11/16/19 10 Backup : p+Pb plots • Mass of Electron pair 11/16/19 11 Status and plan (1) • Status • Research Grant for ‘Study of charmed Xi baryon production in heav y ion collisions(2019/09~2022/08)’ • Just started 5.02 TeV p+Pb and worked on 13 TeV (for qm) • Starting from Jinjoo’s 13 TeV framework. • However, number of e-Xi- pair looks too small in p+Pb. Under investigation. • Short-term-plan • Going back to the analysis • Fix current issue in MC for p+Pb • Resolve issue in 13 TeV analysis, then preliminary early next year 11/16/19 12 Status and Plan (2) • Mid&Long-term plan • 2019 Nov ~ 2020 Feb: solve issues in p+p 13 TeV and p+Pb 5 TeV • 2020 Feb ~ 2020 Apr : Analyze p+p 13 TeV and p+Pb • 2020 May : Hard Probes 2020 (Jinjoo) • 2020 June : prepare theory/sim curve and paper proposal for p+p 5 TeV and p+p 13 TeV • Further study in 2020 • Another paper if p+Pb 5 TeV analysis is successful with enough statistics • High multiplicity 13 TeV to see multiplicity dependence • Extend multiplicity with p+Pb • Further study • Pb+Pb + • �c using 2pi �-, apply ML (see Jaehyun’s slides) 11/16/19 13 11/16/19 14 • largely underestimated compared to the default PYTHIA tune (Monash) • Good agreement including color-reconnection processes between partons created i n different MPIs (can enhance strange and baryon production) • Alternative description that does not require the presence of a QGP-like medium 11/16/19 15 • pythia 8 • uses 2 → 2 processes followed by a leading-logarithmic pT-ordered parton shower for the charm quark pair production • And hadronisation is treated with the Lund string model [66]. • different tunes of hadronization: • Monash 2013 tune • And Mode 0,2,3 tune from • based on a model for the hadronisation of multi-parton systems, which include s string formation beyond the leading-color approximation and is implemented in pythia 8 with specific tuning of the color reconnection parameters. • As compared to the Monash 2013 tune, this model provides a better descriptio n of the measured baryon-to-meson ratios in the light-flavor sector. • Two other tunes (Mode 2 and Mode 3) provided give similar ratios as Mode 0. • The measured ratio is also compared to other models implementing different h adronization mechanisms: dipsy with the rope hadronisation and herwig 7.0.4 with the cluster hadronisation 11/16/19 16 Xic+ • Xic+ à Xi* pi+ à Xi- pi+ pi+ • Xi* : 11/16/19 17 Xic+ • Pdg live charmed baryon • http://pdglive.lbl.gov/Particle.action?node=S045&init=0 • http://pdglive.lbl.gov/BranchingRatio.action?desig=10&parCode=S 045 11/16/19 18.