Inclusive jet cross section in ATLAS

Size: px

Start display at page:

Download "Inclusive jet cross section in ATLAS"

Claude Bruce
5 years ago
Views:

International Fellowship of the European

1 Inclusive jet cross section in ALAS (on behalf of the ALAS collaboration) Pavel Starovoitov CERN he researcher is supported by Marie Curie Incoming International Fellowship of the European Commission s 7th Framework Program under contract number PIIF-GA Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC / 4

2 Outline Jet reconstruction Inclusive jets Dijets 4 Multijets 5 Conclusions Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC / 4

Jet reconstruction particles deposit their energy in calorimeter cells cells Alg D topoclusters D topoclusters anti k t jets Jet response at EM scale ALAS Preliminary Barrel Barrel-Endcap ransition 0.

3 Jet reconstruction particles deposit their energy in calorimeter cells cells Alg D topoclusters D topoclusters anti k t jets Jet response at EM scale ALAS Preliminary Barrel Barrel-Endcap ransition HEC HEC-FCal ransition FCal Anti-k t R =, EM+JES E = 0 GeV E = 60 GeV E = GeV E = 400 GeV E = 000 GeV Jet η det EM+JES calibration restores response JES uncertainty : single hadron response η-intercalibration Fractional JES systematic uncertainty Anti-k t 0 40 R=, EM+JES, 0. ALPGEN + Herwig + Jimmy JES calibration non-closure Single particle (calorimeter) otal JES uncertainty η <, Data 0 + Monte Carlo QCD jets Noise hresholds PYHIA Perugia0 Additional dead material ALAS Preliminary jet Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC / 4

Inclusive jets ALAS-CONF-0-047 he two leading jets are central high-p jets with an invariant mass of.8 ev. hey have (p, y) of (.

4 Inclusive jets ALAS-CONF he two leading jets are central high-p jets with an invariant mass of.8 ev. hey have (p, y) of (.5 ev, -8) and (.0 ev, 4), respectively. he E miss in the event is GeV. Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC 4 / 4

5 Inclusive jets. Introduction he European Physical Journal EPJ C RecognizedbyEuropeanPhysicalSociety volume 7 number february 0 Particles and Fields Update since Summer 0 p > 60 GeV p > 0 GeV y <.8 y < 4.4 L = 7 nb L = 7 pb new (small) JES uncertainty Inclusive jet differential cross section as a function of jet p integrated over the full region y <.8 for jets identified using the anti-kt algorithm with R =. he data are compared to NLO pqcd calculations to which soft QCD corrections have been applied. From the ALAS Collaboration: Measurement of inclusive jet and dijet cross sections in proton-proton collisions at 7 ev centre-of-mass energy with the ALAS detector [GeV] jet p 5 50 Inclusive jet cross section kinematic reach Summer 0, L Winter 0, L Kinematic limit anti-k t - dt = 7 nb - dt = 7 pb jets, R = = 7 ev ALAS Preliminary jet rapidity y s Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC 5 / 4

6 Inclusive jets [pb/gev] dy σ/dp d anti-k t jets, R= - L dt=7 pb, s=7 ev Systematic uncertainties NLO pqcd (CEQ 6.6) Non-pert. corr. y < 0. ( ) 9 0. < y < ( ) 6 < y <. ( ). < y <. ( ) 0. < y <.8 ( ) -.8 < y <.6 ( ) -6.6 < y < 4.4 ( ) ALAS Preliminary p [GeV] two orders of magnitide in p 0GeV < p jet <.5eV seven rapidity bins 4.4 < y jet < 4.4 pqcd corrected for non-perturbative effects good agreement with theory over 7 orders of magnitude Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC 6 / 4

7 Ratio wrt NLO pqcd Inclusive jets vs NLO QCD y < < y < < y <.. < y <. Ratio wrt NLO p.5 ALAS Preliminary.5.5 Ratio wrt NLO pqcd - L dt=7 pb s=7 ev anti-k t jets, R= reasonable agreement within errors 0. < y < Data with < y <. statistical error Systematic uncertainties NLO pqcd (CEQ 6.6) Non-pert. corr.. < y <.. < y <.8.8 < y <.6.6 < y < 4.4 ALAS Preliminary p [GeV] anti-k t jets, R= Data with statistical error Systematic uncertainties NLO pqcd (CEQ 6.6) Non-pert. corr. L d s=7 anti- p [GeV] p [GeV] Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC 7 / 4

8 Inclusive jets in the y < 0. the gluon-gluon subprocess falls quickly from 60% to 5% for jet p.5 ev he quark-gluon scattering grows from 5% to 50% for jet p GeVand it slightly decreases to 0% at high p. the quark-quark subprocesses are very small at low jet p, but it is dominant at high p. fractional contribution anti-k t jets R= (0.0< y <0.). CEQ 6.6 Gluon - Gluon Quark - Gluon ALAS Preliminary (Simulation) Quark - Quark jet Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC 8 / 4

9 Inclusive jets in the y < 0. C is lower at high p than CEQ 6.6 NNPDF.0 NNPDF. HERAPDF.5 has smaller incertainty HERAPDF.0 for high p. GJR compartible with data, but have a different shape /d y σ 0 (CEQ 6.6)/dp /d y /d σ/dp d anti-k t jets. R = (0.0< y <0.) PDF (CL90) Data CEQ 6.6 C ALAS Preliminary NNPDF.0(0) NNPDF.(0) MSW008 /d y σ 0 (CEQ 6.6)/dp /d y /d σ/dp d Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC 8 / 4 anti-k t jets. R = (0.0< y <0.) PDF (CL90) Data CEQ 6.6 HERAPDF.0 HERAPDF.5 GJR 008 ALAS Preliminary

10 Inclusive jets in the. < y <.8 the gluon-gluon subprocess falls quickly from 55% to 5% at very high p the quark-gluon scattering grows from 40 to 60% up to jet p 50 GeVand falls down to 40% at high p s the quark-quark scattering slowly grows from 5% at very low p to 45% at very high transverse momentum. fractional contribution anti-k t jets R= (.< y <.8). CEQ 6.6 Gluon - Gluon Quark - Gluon ALAS Preliminary (Simulation) Quark - Quark jet Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC 9 / 4

11 Inclusive jets in the. < y <.8 C uncertainty is much higher at high p than CEQ 6.6 NNPDF. unceertainty is a bit higher than NNPDF.0 HERAPDF.5 has smaller incertainty HERAPDF.0 for high p. GJR and MSW are compartible with data /d y σ 0 (CEQ 6.6)/dp /d y /d.5 anti-k t jets. R = (.< y <.8) PDF (CL90) /d y.5 Data CEQ 6.6 C NNPDF.0(0) NNPDF.(0) MSW008 σ 0 (CEQ 6.6)/dp σ/dp d ALAS Preliminary /d y /d.5 anti-k t jets. R = (.< y <.8) PDF (CL90).5 Data CEQ 6.6 HERAPDF.0 HERAPDF.5 GJR 008 σ/dp d ALAS Preliminary Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC 9 / 4

12 Inclusive jets in the.6 < y < 4.4 the quark-quark contribution is nearly flat and amounts to 5% the gluon induced processes contribute almost 85% to the cross section fractional contribution. 0. anti-k t jets R= (.6< y <4.4). CEQ 6.6 Gluon - Gluon Quark - Gluon ALAS Preliminary (Simulation) Quark - Quark jet Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC / 4

13 Inclusive jets in the.6 < y < 4.4 CEQ 6.6 and C are incompatible with data at high p. all PDFs predict larger cross sections /d y σ 0 (CEQ 6.6)/dp /d y /d σ/dp d anti-k t jets. R = (.6< y <4.4) PDF (CL90) Data CEQ 6.6 C ALAS Preliminary NNPDF.0(0) NNPDF.(0) MSW008 /d y σ 0 (CEQ 6.6)/dp /d y /d σ/dp d Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC / 4 anti-k t jets. R = (.6< y <4.4) PDF (CL90) Data CEQ 6.6 HERAPDF.0 HERAPDF.5 GJR 008 ALAS Preliminary

14 Ratio wrt NLO pqcd Inclusive jets. Comparison against Powheg y < < y < < y <.. < y <. Ratio wrt NLO p.5 ALAS Preliminary.5.5 Ratio wrt NLO pqcd - L dt=7 pb s=7 ev anti-k t % at low p 0. < y < 0 40% at high p 0% diff. jets, R= Herwig vs Pythia Data with < y <. statistical error Systematic uncertainties NLO pqcd (MSW 008) Non-pert. corr. Powheg + Pythia. < y <. (AMB) Powheg + Herwig (AUE). < y <.8.8 < y <.6.6 < y < 4.4 ALAS Preliminary p [GeV] anti-k t jets, R= Data with statistical error Systematic uncertainties NLO pqcd (MSW 008) Non-pert. corr. Powheg + Pythia (AMB) Powheg + Herwig (AUE) s an p [GeV] p [GeV] Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC / 4

15 Inclusive jets. Summary Cross section measurements for inclusive jet production as a function of jet p have been presented. he largest systematic uncertainty for this measurement arises from the jet energy scale he data have also been compared with the NLO QCD predictions obtained with different PDF sets he data have also been compared with the NLO+PS Powheg prediction, using the MSW 008 NLO PDF set. able: Summary of systematic uncertainties on the inclusive jet cross section measurement for representative p and y regions for anti-k t jets with R =. p [GeV] y Abs. JES Unfolding Cleaning rigger Jet Rec. +40% % 0% % % % +80% % 0% % % % 0 < 0. % % % % % Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC / 4

16 Dijets (ALAS-CONF-0-047) he two leading jets in a forward-backward dijet system produce an invariant mass of 4.0 ev. he two leading jets have (p, y) of (5 GeV, -.9) and (5 GeV,.), respectively. he E miss in the event is GeV. Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC / 4

17 Dijets leading jet p 0 GeV subleading jet p 0 GeV 0GeV < m dijet jj < 4.eV 5 rapidity bins.8 < y jet <.8 NLO QCD corrected for non-perturbative effects Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC 4 / 4

18 Dijets vs NLO QCD reasonable data to theory agreement within errors Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC 5 / 4

19 Dijets vs PDF boundaries of the theory uncertainty bands for various PDF sets are shown Predictions using HERAPDF.5 follow the data most closely Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC 6 / 4

20 Dijets vs POWHEG 50 0% at low mass reasonable at high mass 0% diff. Herwig vs Pythia Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC 7 / 4

21 Dijets. Summary Cross section measurements for dijet production as a function of the invariant mass of the two leading jets have been presented. he largest systematic uncertainty for this measurement arises from the jet energy scale Experimental and theoretical uncertainties are of the similar size. able: Summary of systematic uncertainties on the dijet mass cross section measurement for representative dijet mass m and maximum rapidity y max regions. m [GeV] y max Abs. JES Rel. JES Unfolding Cleaning rig. Jet Rec. +0% % % % % % % 00 < 0. % 0% 5% % % % Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC 8 / 4

22 Multijets (ALAS-CONF-0-04) Event display of a six-jet event. he towers in the bottom right figure represent transverse energy deposited in the calorimeter projected on a grid of eta and phi. Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC 9 / 4

23 otal inclusive jet cross section as a function of multiplicity σ [pb] MC/Data 6 ALAS Preliminary R=, L dt=.4 pb Data ( s=7 ev)+syst. ALPGEN+HERWIG AUE. PYHIA AMB 5 ALPGEN+PYHIA MC Inclusive Jet Multiplicity σ n /σ n MC/Data. ALAS Preliminary - R=, L dt=.4 pb Data ( s=7 ev)+syst. ALPGEN+HERWIG AUE PYHIA AMB ALPGEN+PYHIA MC Inclusive Jet Multiplicity systematic uncertainty in σ(n jets ) is dominated by JES. JES and unfolding systematics are comparable in σ(n jets )/σ(n jets ) Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC 0 / 4

24 Cross section as a function of i-th leading jet p (,) y jet <.8, P jet [pb/gev] d σ/d p MC/Data > 60 GeV, Plead.jet > 80 GeV ALAS Preliminary - R=, L dt=.4 pb Data ( s=7 ev)+syst. ALPGEN+HERWIG AUE. PYHIA AMB 5 ALPGEN+PYHIA MC09. N jets p (leading jet) [GeV] [pb/gev] d σ/d p MC/Data ALAS Preliminary - R=, L dt=.4 pb Data ( s=7 ev)+syst. ALPGEN+HERWIG AUE. PYHIA AMB 5 ALPGEN+PYHIA MC09. N jets nd p ( leading jet) [GeV] JVF > 0.7 (fraction of charged particle p coming from event vertex) Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC / 4

25 Cross section as a function of i-th leading jet p (,4) he jet energy scale systematic uncertainty is the dominant uncertainty in the measurement. [pb/gev] d σ/d p - 4 ALAS Preliminary - R=, L dt=.4 pb Data ( s=7 ev)+syst. ALPGEN+HERWIG AUE. PYHIA AMB 5 ALPGEN+PYHIA MC09. N jets [pb/gev] d σ/d p - 4 ALAS Preliminary - R=, L dt=.4 pb Data ( s=7 ev)+syst. ALPGEN+HERWIG AUE. PYHIA AMB 5 ALPGEN+PYHIA MC09. N jets 4 MC/Data rd p ( leading jet) [GeV] MC/Data th p (4 leading jet) [GeV] he ALPGEN+HERWIG AUE and ALPGEN+PYHIA MC09 Monte Carlo simulations are in agreement with the data within the systematic uncertainties. Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC / 4

26 hree to two jet cross section ratio he systematic uncertainty ( 5%) is dominated by the systematic uncertainties in the unfolding correction possibility to constrain PDFs and α s ] lead /[d σ/d p ] lead [d σ/d p MC/Data ALAS Preliminary - R=, L dt=.4 pb Data ( s=7 ev)+syst. ALPGEN+HERWIG AUE PYHIA AMB ALPGEN+PYHIA MC p (leading jet) [GeV] ] lead /[d σ/d p ] lead [d σ/d p heory/data ALAS Preliminary - R=, L dt=.4 pb Data ( s=7 ev)+syst. NLO+non.pert.+syst p lead [GeV] he ALPGEN+HERWIG AUE describe the data within systematic uncertainties. he shape descriptions from PYHIA AMB do not describe the data well. Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC / 4

27 Conclusions Single inclusive jet and dijet production he agreement of the NLO perturbative QCD predictions with the measurements extends over several orders of magnitude. he data were also compared to several parton distribution function sets. he experimental uncertainties achieved are similar in size to the theoretical uncertainties in some regions of phase space. multijets ALPGEN generally describes the shapes well, whether the HERWIG or PYHIA parton showers are used PYHIA LO+PS does not describe the shapes of some of the studied distributions A measurement of the three to two jet cross section is described by both ALPGEN and a NLO pqcd calculation, albeit with a significant discrepancy in the lowest p bin. Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC 4 / 4

28 BACK-UP Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC 5 / 4

29 JES uncertainty valiadtion Data / MC Multi-jet rack-jet γ -jet direct balance γ -jet MPF JES uncertainty ALAS Preliminary anti-k t R=, EM+JES p jet [GeV] Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC 6 / 4

30 Eta intercalibration uncertainty Relative jet response MC / Data. ALAS Preliminary avg 0 p < 45 GeV. R=, EM+JES Anti-k t Data 0, s = 7 ev 0.9 Data 0, s = 7 ev Pythia Alpgen Herwig++ Perugia0 Intercalibration uncertainty Jet η Relative jet response MC / Data. ALAS Preliminary avg 80 p < GeV. R=, EM+JES Anti-k t Data 0, s = 7 ev 0.9 Data 0, s = 7 ev Pythia Alpgen Herwig++ Perugia0 Intercalibration uncertainty Jet η Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC 7 / 4

31 Inclusive jets in the 0. < y < fractional contribution anti-k t jets R= (0.< y <). CEQ 6.6 Gluon - Gluon Quark - Gluon ALAS Preliminary (Simulation) Quark - Quark jet Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC 8 / 4

32 Inclusive jets in the 0. < y < fractional contribution anti-k t jets R= (0.< y <). CEQ 6.6 Gluon - Gluon Quark - Gluon ALAS Preliminary (Simulation) Quark - Quark jet /d y σ 0 (CEQ 6.6)/dp /d y /d σ/dp d. (CL90) jets. R = (0.< y <) PDF anti-k t Data CEQ 6.6 C ALAS Preliminary NNPDF.0(0) NNPDF.(0) MSW008 /d y σ 0 (CEQ 6.6)/dp /d y /d σ/dp d. (CL90) jets. R = (0.< y <) PDF anti-k t Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC 8 / 4 Data CEQ 6.6 HERAPDF.0 HERAPDF.5 GJR 008 ALAS Preliminary

33 Inclusive jets in the < y <. fractional contribution anti-k t jets R= (< y <.). CEQ 6.6 Gluon - Gluon Quark - Gluon ALAS Preliminary (Simulation) Quark - Quark jet Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC 9 / 4

34 Inclusive jets in the < y <. fractional contribution anti-k t jets R= (< y <.). CEQ 6.6 Gluon - Gluon Quark - Gluon ALAS Preliminary (Simulation) Quark - Quark jet /d y σ 0 (CEQ 6.6)/dp /d y /d σ/dp d anti-k t jets. R = (< y <.) PDF (CL90) Data CEQ 6.6 C ALAS Preliminary NNPDF.0(0) NNPDF.(0) MSW008 /d y σ 0 (CEQ 6.6)/dp /d y /d σ/dp d anti-k t jets. R = (< y <.) PDF (CL90) Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC 9 / 4 Data CEQ 6.6 HERAPDF.0 HERAPDF.5 GJR 008 ALAS Preliminary

35 Inclusive jets in the. < y <. fractional contribution anti-k t jets R= (.< y <.). CEQ 6.6 Gluon - Gluon Quark - Gluon ALAS Preliminary (Simulation) Quark - Quark jet Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC 0 / 4

36 Inclusive jets in the. < y <. fractional contribution anti-k t jets R= (.< y <.). CEQ 6.6 Gluon - Gluon Quark - Gluon ALAS Preliminary (Simulation) Quark - Quark jet /d y σ 0 (CEQ 6.6)/dp /d y /d σ/dp d anti-k t jets. R = (.< y <.) PDF (CL90) Data CEQ 6.6 C ALAS Preliminary NNPDF.0(0) NNPDF.(0) MSW008 /d y σ 0 (CEQ 6.6)/dp /d y /d σ/dp d anti-k t jets. R = (.< y <.) PDF (CL90) Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC 0 / 4 Data CEQ 6.6 HERAPDF.0 HERAPDF.5 GJR 008 ALAS Preliminary

37 Inclusive jets in the.8 < y <.6 fractional contribution. anti-k t jets R= (.8< y <.6). CEQ 6.6 Gluon - Gluon Quark - Gluon ALAS Preliminary (Simulation) Quark - Quark jet Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC / 4

38 Inclusive jets in the.8 < y <.6 fractional contribution. anti-k t jets R= (.8< y <.6). CEQ 6.6 Gluon - Gluon Quark - Gluon ALAS Preliminary (Simulation) Quark - Quark jet /d y σ 0 (CEQ 6.6)/dp /d y /d σ/dp d.5 anti-k t jets. R = (.8< y <.6) PDF (CL90) Data NNPDF.0(0).5 0 CEQ 6.6 C ALAS Preliminary NNPDF.(0) MSW008 /d y σ 0 (CEQ 6.6)/dp /d y /d σ/dp d anti-k t jets. R = (.8< y <.6) PDF (CL90) Data HERAPDF.5 CEQ 6.6 HERAPDF.0 GJR 008 Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC / 4 ALAS Preliminary

39 Dijets (R=) Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC / 4

40 Dijets (R=) vs NLO QCD Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC / 4

41 Multijets(R=). / ] lead /[d σ/d p ] lead [d σ/d p MC/Data ALAS Preliminary - R=, L dt=.4 pb Data ( s=7 ev)+syst. ALPGEN+HERWIG AUE PYHIA AMB ALPGEN+PYHIA MC p (leading jet) [GeV] ] lead /[d σ/d p ] lead [d σ/d p heory/data ALAS Preliminary - R=, L dt=.4 pb Data ( s=7 ev)+syst. NLO+non.pert.+syst p lead [GeV] Pavel Starovoitov (CERN) Inclusive jets in ALAS Standard LHC 4 / 4

Measurement of multijets and the internal structure of jets at ATLAS

Measurement of multijets and the internal structure of jets at ALAS Bilge M. Demirköz, on behalf of the ALAS Collaboration Institut de Fisica d Altes Energies, Barcelona, SPAIN also at Middle East echnical