Particle spectra in Minimum Bias events at 13TeV Juan Manuel Grados Luyando on behalf of the CMS collaboration Deutsches Elektronen-Synchrotron, Hamburg MPI@LHC 2015 Trieste, Italy 1
Motivation Probe the different components of hadron production The transition from the perturbative to the non-perturbative region Behaviour of QCD at small-x Multiple parton interactions Saturation of parton densities Soft diffractive components Tune the modeling of these contributions Center-of-mass energy dependence Taming of the cross section in the low p T region Juan Manuel Grados Luyando MPI@LHC Trieste, Italy November 2015 2
Multiple Parton Interactions Multiple Parton Interactions Soft to semi-hard interactions Phenomenological models Tuning of the model parameters based on experimental data Comparison to the new CMS tunes Simultaneous fits to CDF UE data at 0.9 and 1.96 TeV, and CMS UE at 7 TeV Energy dependence of the MPI parameters Different parton densities Theoretical uncertainties from allowed parameter space Juan Manuel Grados Luyando MPI@LHC Trieste, Italy November 2015 3
Pseudorapidity at 0T • Measurement of pseudorapidity distribution of charged hadrons in proton-proton collisions at √ s = 13 TeV • Presented for inelastic events • No minimum transverse momentum requirement ( measurement done at 0T ) • Corrected to primary long-lived charged hadrons (no leptons) CMS 0.06 pp √ s = 13 TeV 0.05 0.04 data fraction PYTHIA 8 CUETP8M1 0.03 E POS L HC 0.02 0.01 0 0 10 20 30 40 50 number of reconstructed tracks Phys. Lett. B 751 (2015) 143–163 Juan Manuel Grados Luyando MPI@LHC Trieste, Italy November 2015 4
Pseudorapidity at 0T • Measurement of pseudorapidity distribution of charged hadrons in proton-proton collisions at √ s = 13 TeV • Presented for inelastic events • No minimum transverse momentum requirement ( measurement done at 0T ) • Corrected to primary long-lived charged hadrons (no leptons) Charged-particle multiplicity, √ s = 13 TeV 9 dN ch / d η 8 7 6 5 Data 4 CUETP 8 S 1 -CTEQ 6 L 1 3 CUETP 8 M 1 PYTHIA 8 Tune 4 C 2 1 0 1 . 15 1 . 1 MC/Data 1 . 05 1 . 0 0 . 95 0 . 9 0 . 85 0 . 8 - 2 - 1 . 5 - 1 - 0 . 5 0 . 5 1 . 5 0 1 2 η PHYTHIA8 (CUETP8M1 and CUETP8S1) and EPOS LHC agree with the measurement within the error bands Phys. Lett. B 751 (2015) 143–163 Juan Manuel Grados Luyando MPI@LHC Trieste, Italy November 2015 5
Pseudorapidity at 0T • Measurement of pseudorapidity distribution of charged hadrons in proton-proton collisions at √ s = 13 TeV • Presented for inelastic events • No minimum transverse momentum requirement ( measurement done at 0T ) • Corrected to primary long-lived charged hadrons (no leptons) PHYTHIA8 (CUETP8M1 and CUETP8S1) and EPOS LHC agree with the measurement within the error bands Phys. Lett. B 751 (2015) 143–163 Juan Manuel Grados Luyando MPI@LHC Trieste, Italy November 2015 6
Pseudorapidity at 8 TeV • Measurement of pseudorapidity distribution of charged particles in proton-proton collisions at √ s = 8 TeV • Presented for different diffractive event selections (TOTEM event selection) • Corrected down to zero transverse momentum • Corrected to all charged particles TOTEM acceptance: 5.3 < | η | < 6.4 -1 -1 -1 Inclusive pp NSD-enhanced pp CMS-TOTEM, s = 8 TeV, L = 45 b SD-enhanced pp CMS-TOTEM, s = 8 TeV, L = 45 b µ CMS-TOTEM, s = 8 TeV, L = 45 b µ µ 5 η η η 8 8 /d /d /d Data Pythia6 Z2* ch ch ch Pythia8 4C dN dN dN 7 7 Herwig++ EE3-CTEQ6L1 4 EPOS LHC QGSJetII-04 6 6 3 5 5 Data Data Pythia6 Z2* Pythia6 Z2* 2 4 4 Pythia8 4C Pythia8 4C Herwig++ EE3-CTEQ6L1 Herwig++ EE3-CTEQ6L1 EPOS LHC EPOS LHC 3 3 1 QGSJetII-04 QGSJetII-04 N 1 in 5.3< <6.5 and -6.5< <-5.3 ≥ η η N 1 in only 5.3< <6.5 or only -6.5< <-5.3 N 1 in 5.3< <6.5 or -6.5< <-5.3 ≥ η η ≥ η η 2 2 ch ch ch MC / Data 0 1 2 3 4 5 6 MC / Data 0 1 2 3 4 5 6 MC / Data 0 1 2 3 4 5 6 1.2 1.2 1.5 1 1 1 0.8 0.8 0 1 2 3 4 5 6 0 1 2 3 4 5 6 0 1 2 3 4 5 6 | | | | | | η η η Eur. Phys. J. C (2014) 74:3053 Juan Manuel Grados Luyando MPI@LHC Trieste, Italy November 2015 7
Pseudorapidity at 8 TeV • Measurement of pseudorapidity distribution of charged particles in proton-proton collisions at √ s = 8 TeV • Presented for different diffractive event selections (TOTEM event selection) • Corrected down to zero transverse momentum • Corrected to all charged particles TOTEM acceptance: 5.3 < | η | < 6.4 CMS+TOTEM, d N ch /d( | η | ) √ s = 8 TeV, Inclusive pp CMS+TOTEM, d N ch /d( | η | ) √ s = 8TeV, NSD-enhanced CMS+TOTEM, d N ch /d( | η | ) √ s = 8 TeV, SD-enhanced (d N ch )/d( | η | ) (d N ch )/d( | η | ) (d N ch )/d( | η | ) 9 9 5 8 8 CMS+TOTEM data 7 7 4 CUETP 6 S 1 6 6 CUETP 8 S 1 -CTEQ 6 L 1 3 CUETP 8 S 1 -HERAPDF 1 . 5 LO 5 5 CUETP 8 M 1 4 4 CMS+TOTEM data CMS+TOTEM data 2 3 3 CUETP 6 S 1 CUETP 6 S 1 CUETP 8 S 1 -CTEQ 6 L 1 CUETP 8 S 1 -CTEQ 6 L 1 2 2 1 CUETP 8 S 1 -HERAPDF 1 . 5 LO CUETP 8 S 1 -HERAPDF 1 . 5 LO 1 1 CUETP 8 M 1 CUETP 8 M 1 0 0 0 1 . 4 1 . 4 1 . 4 1 . 2 1 . 2 1 . 2 MC/data MC/data MC/data 1 1 1 0 . 8 0 . 8 0 . 8 0 . 6 0 . 6 0 . 6 0 1 2 3 4 5 6 0 1 2 3 4 5 6 0 1 2 3 4 5 6 | η | | η | | η | Results after tuning Eur. Phys. J. C (2014) 74:3053 Juan Manuel Grados Luyando MPI@LHC Trieste, Italy November 2015 8
Pseudorapidity Predictions Event selection We can implement a similar event selection but instead of TOTEM we use particles in the range 3 < | η | < 5 (HF calorimeter) in the following way: Non-Single Diffractive enhanced: at least one particle with E> 5 GeV on each side. Single Diffractive enhanced: at least one particle with E> 5 GeV on one side. Other side no particle with E> 5 GeV. Inelastic enhanced: at least one particle on either side with E> 5 GeV. Particle selection -2.4 < | η | < 2.4 (Tracker acceptance) pT > 500MeV Final State Charged particles Juan Manuel Grados Luyando MPI@LHC Trieste, Italy November 2015 9
Pseudorapidity at 3.8T and diffractive events. Predictions Selection: inclusive pp inel. enhanced: E part > 5 GeV in − 5 < η < − 3 or 3 < η < 5 4 4 dN dN d η d η T h e s h a p e o f a l l t h e N N 1 3 . 5 1 3 . 5 3 3 predictions for the inclusive 2 . 5 2 . 5 and inelastic selections is 2 2 1 . 5 1 . 5 P 8 -CUETP 8 -heradpdf P 8 -CUETP 8 -heradpdf very similar , only changing P 8 -CUETP 8 M 1 P 8 -CUETP 8 M 1 1 1 P 8 - 4 C P 8 - 4 C the predicted value by ~0.5 P 8 -Monash P 8 -Monash 0 . 5 0 . 5 EPOS-LHC EPOS-LHC 0 0 particles per η unit. 1 . 3 1 . 3 1 . 2 1 . 2 MC/Data MC/Data 1 . 1 1 . 1 1 . 0 1 . 0 0 . 9 0 . 9 0 . 8 0 . 8 0 . 7 0 . 7 For the NSD selection : 0 . 6 0 . 6 - 2 - 1 . 5 - 1 - 0 . 5 0 0 . 5 1 1 . 5 2 - 2 - 1 . 5 - 1 - 0 . 5 0 0 . 5 1 1 . 5 2 η η PYTHIA8 Tunes predict the NSD enhanced: E part > 5 GeV in − 5 < η < − 3 and 3 < η < 5 SD enhanced: E part > 5 GeV in either − 5 < η < − 3 or 3 < η < 5 same shape with different 4 2 dN dN d η d η N N 1 3 . 5 1 values, while EPOS-LHC has 3 1 . 5 a valley in the central region. 2 . 5 2 1 1 . 5 P 8 -CUETP 8 -heradpdf P 8 -CUETP 8 -heradpdf P 8 -CUETP 8 M 1 P 8 -CUETP 8 M 1 For the SD selection : 0 . 5 1 P 8 - 4 C P 8 - 4 C P 8 -Monash P 8 -Monash 0 . 5 PYTHIA8 Tunes predict EPOS-LHC EPOS-LHC 0 0 1 . 3 1 . 3 s i g n i fi c a n t l y d i f f e r e n t 1 . 2 1 . 2 MC/Data MC/Data 1 . 1 1 . 1 1 . 0 1 . 0 behaviour than EPOS-LHC . 0 . 9 0 . 9 0 . 8 0 . 8 0 . 7 0 . 7 0 . 6 0 . 6 - 2 - 1 . 5 - 1 - 0 . 5 0 0 . 5 1 1 . 5 2 - 2 - 1 . 5 - 1 - 0 . 5 0 0 . 5 1 1 . 5 2 η η Juan Manuel Grados Luyando MPI@LHC Trieste, Italy November 2015 10
Integrated-pT Measuring on different diffractive event topologies Will provide further constrains for the models Show where each model does a good/bad description Integrated pT spectrum Total 2 —> 2 partonic cross section: Divergent towards low pT —> phenomenological factor [ α 2 s ( p 2 T, 0 + p 2 T ) / α 2 s ( p 2 T )][ p 4 T / ( p 2 T, 0 + p 2 T ) 2 ] Juan Manuel Grados Luyando MPI@LHC Trieste, Italy November 2015 11
Integrated-pT at 8 TeV pp s = 8 TeV CMS Integrated pT spectrum ) min N (p > 40 MeV) > 0 in 5.3 < | | < 6.5 η ch T T r(p 10 Leading charged particles, | | < 2.4 η 1 At √ s = 8 TeV the turn over − 1 happens at p T -min ~ 5GeV 10 − 2 10 Data Pythia 6 Z2* 3 − 10 Pythia 6 CUET Pythia 6 (default, MPI on) Pythia 6 (default, MPI off) − 4 10 Pythia 6 (default, MPI off, no sat) MC/Data MC scaled to data at p = 9 GeV 1.5 T, min 1 0.5 1 10 p [GeV] T min arXiv:1507.00233 Juan Manuel Grados Luyando MPI@LHC Trieste, Italy November 2015 12
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