Precision Forward Measurements at LHCb with Vector Bosons. Philip Ilten on behalf of the LHCb Collaboration. Massachusetts Institute of Technology

Transcription

1 Precision Forward Measurements at with Vector Bosons Philip Ilten on behalf of the Collaboration Massachusetts Institute of echnology Radcor-Loopfest Ilten Measurements with June 18, / 37

2 Introduction Detector JINS 3 (28) S85 5 m muon system magnet ECAL RICH2 O VELO I SPD/PRS RICH1 1 3 y-axis 2 M1 HCAL M2 M3 M4 M5 z-axis 5 m 15 m fully instrumented between 2 < η < 5 performance documented in Int. J. Mod. Phys. A 3 (215) 7 momentum resolution between.4% at 5 GeV to 1% at 2 GeV impact parameter resolution of /p m secondary vertex precision of.1.5(.1.3) mm in xy(z) Ilten Measurements with June 18, / 37

3 Introduction rigger L HL1 JINS 8 (213) P422 HL2 : p > 1.5 GeV 34 khz : p 1 p2 > 1.3 GeV 75 khz h: E > 3.5 GeV 45 khz : p > 4.8(1) GeV.7(5) khz : m > 2.7(1)GeV 1.2(1.3) khz 1 MHz 5 khz track: p > 1.7 GeV 33 khz : p > 1(4.8) GeV : m > 4.8(3) GeV displaced vertex e: E > 2.5 GeV 16 khz e: p > 1 GeV inclusive topological beauty BBD γ: E > 2.5 GeV 8 khz... inclusive and exclusive charm movable L thresholds and software HL low p leptons/photons and tracks (IP >.1 mm) 15 MHz 5 khz Ilten Measurements with June 18, / 37...

4 Introduction Datasets JINS 9 (214) 12, P125 1 fb 1 pp collisions at s = 7 ev (211) 2 fb 1 pp collisions at s = 8 ev (212) 1.1 nb 1 ppb collisions at s = 5 ev (213).5 nb 1 Pbp collisions at s = 5 ev (213) excellent luminosity uncertainty 1.71% for 7 ev dataset 1.16% for 8 ev dataset [ fb 1] [ fb 1] L L ALAS CMS s = 7 ev (211) 28/2 9/4 19/5 29/6 8/8 18/9 28/1 date [day/month] ALAS CMS s = 8 ev (212) 28/2 18/4 5/6 23/7 9/9 27/1 14/12 date [day/month] Ilten Measurements with June 18, / 37

5 Inclusive W /Z Measurements Inclusive W /Z Measurements Ilten Measurements with June 18, / 37

6 Inclusive W /Z Measurements Inclusive W arxiv: fb 1 7 ev dataset W [ν] final state signal fiducial definition 2. < η() < 4.5 p () > 2 GeV purity of 77% Events per 1 GeV/c 2 1 Events per.2 mm < η < 4.5 JHEP 144 (214) 91 Data Fit W ν 1 Data Fit Pseudo- W (data) W τν (simulation) bb+cc X (simulation) JHEP 144 (214) IP [mm] K/π ν Electroweak - Heavy flavour Pull p [GeV/c] Ilten Measurements with June 18, / 37

7 Inclusive W /Z Measurements Inclusive W : Systematics arxiv: source δ σ(w + ) [%] δ σ(w ) [%] δ RW [%] template shape template normalization reconstruction efficiency selection efficiency acceptance and FSR systematic statistical luminosity Ilten Measurements with June 18, / 37

8 Inclusive W /Z Measurements > Inclusive W : Integrated σ arxiv: compared with fixed order FEWZ using MSW8, NNPDF 2.3, C1, ABM12, HERA15, JR9 σ(w + ) = 878. ± 2.1 ± 6.7 ± 15. pb σ(w ) = ± 2. ± 5.3 ± 11.8 pb R W = ±.5 ±.9 :5 s =575eV Data stat Data tot MSW+8 NNPDF3+ C-+ ABM-2 HERA-5 JR+9 p >52+5GeV]c 2[+5<5η <54[5 2 Z:56+5<5M <5-2+5GeV]c [pb] ν > 8cc JM s =M7MeV Data Data statm syst p >M4cMGeV/c 4GcM<M η <M%Gr σ W Z Z ν -[2 -[25 -[3 -[35 σ W 6 6 ν σ W 7rc 7cc Data statm systm beamm lumi MSWc8 68G.3MCLMellipseMarea NNPDF.c C<c ABM<4 HERA<r JRc σ W Z [pb] Z ν 6rc σ 6 W 6 [pb] ν 8rc 9cc 9rc σ W R R ν [pb] Ilten Measurements with June 18, / 37

9 Inclusive W /Z Measurements Inclusive W : Differential σ arxiv: [pb] dσ W ν/dη heory/data 8, s = 7 ev p > 2 GeV/c + Datastat (W ) + Datatot (W ) - Datastat (W ) - Datatot (W ) MSW8 NNPDF3 C1 ABM12 HERA15 JR η R W heory/data p > 2 GeV/c, s = 7 ev Datastat MSW8 Datatot NNPDF3 C1 ABM12 HERA15 JR η A heory-data p > 2 GeV/c η, s = 7 ev Datastat MSW8 Datatot NNPDF3 C1 ABM12 HERA15 JR η Ilten Measurements with June 18, / 37 η

10 Inclusive W /Z Measurements Inclusive W : Comparison arxiv: dσ W ν/dη [pb] 6 4 p > 2 GeV/c 2 M > 4 GeV/c E miss > 25 GeV A l s = 7 ev + 2 (211 extrapolated) W + ν - - (211 extrapolated) W ν + ALAS (21) W + ν - - ALAS (21) W ν l p > 2 GeV/c 2 M > 4 GeV/c E miss > 25 GeV A η p > 2 GeV/c.2.4 s = 7 ev (211 extrapolated) W ν ALAS (21) W ν and W eν.2.4 s = 7 ev (211 extrapolated) W ν CMS (211) W ν η l Ilten Measurements with June 18, / 37 η

11 Inclusive W /Z Measurements Inclusive Z[] arxiv: fb 1 7 ev dataset signal fiducial definition 2. < η() < 4.5, p () > 2 GeV 6 < M () < 12 GeV purity of 99.3% beam energy uncertainty of 1.3% source δ σ(z) [%] δ RWZ [%] δ RW + Z [%] δ RW Z [%] trigger efficiency ID efficiency tracking efficiency final state radiation purity GEC efficiency systematic statistical luminosity 1.72 Ilten Measurements with June 18, / 37

12 Inclusive W /Z Measurements 9 Inclusive Z[]: Integrated σ arxiv: compared with fixed order FEWZ using MSW8, NNPDF 2.3, C1, ABM12, HERA15, JR9 [pb] R ν σ W R <c6c <ccc 96c 9cc Ji s =iriev Data Data stati syst Data stati systi beami lumi MSWc8 NNPDF.c C<c ABM<4 HERA<6 JRc9 p >i4cigev/c 4Gci<i η <i:g6 Z:i%ci<iM 4 <i<4cigev/c %8G.FiCLiellipseiarea :5 s =575eV Data stat Data tot MSW[8 NNPDF3[ C][ ABM]2 HERA]5 JR[9 p >52[5GeV+c 2-[5<5η < Z:56[5<5M <5]2[5GeV+c 86c rc r6 8c σ Zi > [pb] R 7[ [ 82 σ Z [pb] Z 6 σ Z W Z ν ][-8 ]] ]]-2 ]]-4 ]]-6 ]]-8 ]2 ]2-2 σ Z5 Z 6 [pb] ν 9 σ W 8// r:/ r// J s =MrMeV Data Data stat syst Data stat syst beam lumi MSW/8 NNPDF4/ Cc/ ABMc< HERAc: JR/9 p >M</MGeVGc <>/M< η <M.>: Z:M%/M<MM < <Mc</MGeVGc %8>43MCLMellipseMarea σ 6 W 6 ν σ Z5 Z 6 %:/ σ W5 ν ]9-5 2[ 2[-5 2] 2]-5 22 σ Z5 Z 6 r/ r: 8/ σ Z 9 [pb] R Ilten Measurements with June 18, / 37

13 Inclusive W /Z Measurements Inclusive Z[]: Differential σ arxiv: Z 8 Z dσ/dy 7, s = 7 ev Data tot Data stat dσ dy σ 1 1, s = 7 ev Data tot 6 5 MSW8 NNPDF3 C1.8 Data stat RESBOS 4 ABM12 HERAPDF1.5.6 POWHEG+HERWIG 3 JR y Z y Z ] -1 ] -1 [(GeV/c),Z dσ dp.1.8, s = 7 ev Data tot Data stat RESBOS [(GeV/c),Z dσ dp.1.8, s = 7 ev Data tot Data stat HERWIRI σ 1.6 POWHEG+HERWIG σ 1.6 HW: 2 <k > = GeV/c HW: 2 <k > = 2.2 GeV/c p [GeV/c],Z p [GeV/c],Z Ilten Measurements with June 18, / 37

14 Inclusive W /Z Measurements Inclusive Z[ee] JHEP 155 (215) fb 1 8 ev dataset (7 ev JHEP 132 (213) 16) signal fiducial definition same as inclusive Z[] purity of 93% source δ σ(z) [%] track efficiency 1. kinematic efficiency.6 ID efficiency.7 global event cut.6 trigger efficiency.1 background.4 systematic 1.6 statistical.4 luminosity 1.2 comparison with fixed order FEWZ - 8CeVCZC e + e DataCAstat.B DataCAtot.B NNLO/MSW8 NNLO/CEQ1 NNLO/NNPDF23 NNLO/NNPDF3 NNLO/ABM σapp Z + e e BC[pb] Ilten Measurements with June 18, / 37

15 Inclusive W /Z Measurements Inclusive Z[ee]: Differential σ JHEP 155 (215) 19 [pb] Z dσ/dy (1/σ)dσ/dφ* ev Z e + e Data (stat.) Data (tot.) NNLO/MSW8 NNLO/C1 NNLO/NNPDF23 NNLO/NNPDF3 NNLO/ABM ev Z e + e Data (stat.) Data (tot.) Pythia8.1 Resbos Powheg φ* y Z Z (1/σ)dσ/dy Prediction/data ev Z e + e Data (stat.) Data (tot.) Pythia8.1 Resbos Powheg ev Z e + e Data (stat.) Data (tot.) Pythia8.1 Resbos Powheg φ* y Z Ilten Measurements with June 18, / 37

16 Z + X Measurements Z + X Measurements Ilten Measurements with June 18, / 37

17 Z + X Measurements Z + j JHEP 141 (214) fb 1 7 ev dataset Z[] + j final state signal fiducial definition same as inclusive Z[] R(, j) >.4 jet definition anti-k with R =.5 p (j) > 1, 2 GeV 2. < η(j) < 4.5 purity of 99.6% Z + b analysis in JHEP 1412 (214) 79 Fraction of events Data Simulation jet p / p Z source δ σ [%] unfolding 1.5 Z reconstruction 3.5 jet scale, resolution, rec. 7.8 final state radiation.2 systematic 8.6 statistical 1.6 luminosity 3.5 Ilten Measurements with June 18, / 37

18 Z + X Measurements Z + j: Integrated σ JHEP 141 (214) 33 comparison with fixed order FEWZ and showered POWHEG MSW8, CEQ1, and NNPDF 2.3 PDF sets used min p (j) [GeV] σ(z + j)/σ(z) [pb] σ(z + j) [pb] 1.29 ±.2 ± ±.2 ± 1.2 ± ±.1 ± ±.1 ±.5 ±.2 σ(z+jet) σ(z) jet p > 2 GeV s = 7 ev Data Data (stat.) Data (tot.) POWHEG + PYHIA, MSW8, O(α s) POWHEG + PYHIA, MSW8, O(α 2 s ) POWHEG + PYHIA, CEQ1, O(α 2 s ) POWHEG + PYHIA, NNPDF 2.3, O(α 2 s ) FEWZ, MSW8, O(α 2 s ) σ(z+jet) σ(z).32 Data (stat.) Data (tot.).3 jet p > 1 GeV POWHEG + PYHIA, MSW8, O(α s) POWHEG + PYHIA, MSW8, O(α 2 ).28 s s = 7 ev Data POWHEG + PYHIA, CEQ1, O(α 2 s ) POWHEG + PYHIA, NNPDF 2.3, O(α 2 s ).26 FEWZ, MSW8, O(α 2 s ) Ilten Measurements with June 18, / 37

19 Z + X Measurements Z + j: Differential σ JHEP 141 (214) 33 [1/GeV] Z dσ dp σ 1 [1/GeV] jet dσ dp σ jet p > 2 GeV s = 7 ev Data Data (stat.) Data (tot.) POWHEG + PYHIA: MSW8, O(α s) MSW8, O(α 2 s ) CEQ1, O(α 2 s ) NNPDF 2.3, O(α 2 s ) pz [GeV] -1 1 jet p > 1 GeV s = 7 ev Data Data (stat.) Data (tot.) POWHEG + PYHIA: MSW8, O(α s) MSW8, O(α 2 s ) CEQ1, O(α 2 s ) NNPDF 2.3, O(α 2 s ) dσ d φ σ 1 d σ d y σ jet p > 2 GeV s = 7 ev Data Data (stat.) Data (tot.) POWHEG + PYHIA: MSW8, O(α s ) MSW8, O(α 2 s ) CEQ1, O(α 2 s ) NNPDF 2.3, O(α 2 s ) φ jet p > 2 GeV s = 7 ev Data Data (stat.) Data (tot.) POWHEG + PYHIA: MSW8, O(α s) MSW8, O(α 2 s ) CEQ1, O(α 2 s ) NNPDF 2.3, O(α 2 s ) jet p [GeV] y Ilten Measurements with June 18, / 37

20 Z + X Measurements Z + D JHEP 144 (214) fb 1 7 ev dataset Z[] + c-hadron final state D [K π + ], D + [K π + π + ] D + s [π + φ[k + K ]], Λ + c [pk π + ] signal fiducial definition same as inclusive Z[] 3.2 < p(k, π) < 1 GeV p (K, π) > 25 MeV 2 < y(d) 2 < p (D) < 12 GeV 7 D and 4 D + observed purity of 95.6% feed-down from simulation combinatorial from 2D mass pile-up from χ 2 vertex fit [GeV] m K π Z + D m + [GeV] source δ σ(d ) [%] δ σ(d + ) [%] efficiency pile-up.6.6 feed-down B D systematic statistical luminosity Ilten Measurements with June 18, / 37

21 Z + X Measurements Z + D: Cross-section JHEP 144 (214) 91 single parton scattering (SPS) from fixed order MCFM using MSW8 corrected for fragmentation double parton scattering (DPS) using pocket formula σ(ab) = σ(a)σ(b)/σ eff crossmsectionm[fb] mdatam s=7mev SPSmmassive SPSmmassless DPS Z and D cross-sections from σ(z + D ) = 2.5 ± 1.12 ±.22 pb 2 1 σ(z + D + ) =.44 ±.23 ±.3 pb D + D + Ds + Λc Ilten Measurements with June 18, / 37

22 W + j Measurements W + j Measurements Ilten Measurements with June 18, / 37

23 W + j Measurements Q-tagging arxiv: build 2-body SVs n-body SVs from linking 2-body SVs with shared tracks require vertex flight direction within jet, R(SV, j) <.5 two BDs BD(bc udsg): udsg-jet from b, c-jet BD(b c): b-jet from c-jet PV SV jet variable separation variable separation M (SV) udsgc b M cor (SV) udsgb c min(fd (SV)) udsg cb p (SV)/p (j) udsg cb R(SV, j) udsg cb N (trk) udsgc b N (trk j) udsgc b Q(SV) udsgb c log(χ 2 FD (SV)) all log(χ2 IP (SV)) all Ilten Measurements with June 18, / 37

24 W + j Measurements Q-tagging: Flavor arxiv: fit 2-dimensional BD(bc udsg) versus BD(b c) distributions BD(b c) 1.5 udsg-jets BD(b c) 1.5 c-jets BD(b c) 1.5 b-jets -.5 simulation BD(bc udsg) -.5 simulation BD(bc udsg) -.5 simulation BD(bc udsg) candidates 8 data 6 b c 4 udsg candidates 6 4 data b c udsg BD(bc udsg) BD(b c) Ilten Measurements with June 18, / 37

25 W + j Measurements Q-tagging: Efficiency arxiv: determine efficiency with: N x (SV) N x (χ 2 x udsg, c, b IP ), c-enhanced (D + j) b-enhanced (B + j) χ 2 IP of hardest-p track (large initial udsg-background) candidates D+jet data b c udsg log(χ 2 ) IP candidates 2 1 B+jet data b c udsg log(χ 2 ) IP χ 2 IP of hardest-p muon (only O(1%) of jets) candidates data b c udsg D+jet muon log(χ 2 ) IP candidates 2 1 data b c udsg B+jet muon log(χ 2 ) IP Ilten Measurements with June 18, / 37

26 W + j Measurements Q-tagging: Results arxiv: (b,c)-jet tag efficiency simulation b-jet c-jet 2.2 < η(jet) < < p (jet) < 1 GeV SV-tag efficiency b-jet c-jet light-parton mistag probability p (jet) [GeV] Ilten Measurements with June 18, / 37

27 W + j Measurements Q-tagging: Systematics arxiv: source b-jets c-jets BD templates 2% 2% udsg-jet large IP component 5% 1 3% IP resolution hadron-as-muon (hardest- only) 5% 2% out-of-jet (b, c)-hadron decay gluon splitting 1% 1% pile up systematic (combined fit) 1% 1% dependent on jet type and p Ilten Measurements with June 18, / 37

28 W + j Measurements W + b, c arxiv: ev and 8eV datasets fiducial definition: same as inclusive W p (j) > 2 GeV 2.2 < η(j) < 4.2 R(, j) >.5 p ( + j) > 2 GeV W + j content from isolation fit BD(bc udsg) and BD(b c) fit W + b-jet: top extrapolated from side-band W + c-jet: Z[ττ] from p (SV)/p (j) fit Candidates/.5 4 Data W Z 2 Jets +, s = 8 ev, s = 8 ev p ()/p (j ) Ilten Measurements with June 18, / 37

29 W + j Measurements W + b, c: Systematics (5) arxiv: source δ σ(wb) σ(wj) [%] δ σ(wc) σ(wj) [%] δ σ(wj) σ(zj) [%] δ A(Wb) δ A(Wc) (b, c)-tag efficiency 1 1 isolation templates top 13.2 SV-tag BD templates Z[ττ] 3 jet reconstruction 2 2 jet energy trigger and selection W [τν] 1 other electroweak systematic statistical (7 ev) statistical (8 ev) Ilten Measurements with June 18, / 37

30 W + j Measurements W + b, c: Ratios arxiv: s = 7 ev data s = 8 ev data s = 7 ev data s = 8 ev data 6 σ(wx)/σ(wj) σ(wj)/σ(zj) A(Wx).8 s = 7 ev data = 8 ev data s points data (total, stat) fills MCFM NLO theory C1 (scale + PDF) green W + c-jet red W + b-jet blue W + + j magenta W + j Ilten Measurements with June 18, / 37

31 W + j Measurements op arxiv: tightened fiducial region p () > 25 GeV reduces di-jet background 5 < p (b) < 1 GeV reduces W + b similar analysis strategy to W + b, c ratios fit p ( + b) and A distributions to determine significance use excess from W + b prediction to calculate cross-section Candidates/.5 1 Data W Z Jets +jet Candidates/ b-tag Data W Z Jets p ()/p ) (j p ()/p ) (j Ilten Measurements with June 18, / 37

32 W + j Measurements op: Background arxiv: N(W+jet) Data SM p (+j ) [GeV] Charge Asymmetry Data SM p (+j ) [GeV] constrain W + b background using W + j from data and W + b/w + j from theory theory and experimental uncertainties partially cancel validate against W + c N(W+c) 2 Data 15 SM p (+c) [GeV] Ilten Measurements with June 18, / 37

33 W + j Measurements op: Significance arxiv: profile likelihood used to compare W + b hypothesis with W + b + top uncertainties treated as Gaussian nuisance parameters 5.4σ significance observed source δ σ [%] GEC 2 p ()/p (j ) templates 5 1 jet reconstruction 2 SV-tag BD templates 5 b-tag efficiency 1 trigger & selection 2 jet energy 5 W [τ[νν]ν] 1 luminosity 1 2 N(W+b) 2 1 Data Wb+top Wb p (+b) [GeV] Charge Asymmetry Data Wb+top Wb p (+b) [GeV] Ilten Measurements with June 18, / 37

34 W + j Measurements op: Cross-section arxiv: cross-section determined from subtracting W + b background from data 4 s = 7 ev data s = 8 ev data σ(tt + t + t) [fb] points fills σ(t t + t + t) data (total, stat) MCFM NLO theory C1 (scale + PDF) 1 Ilten Measurements with June 18, / 37

35 Conclusions Conclusions Ilten Measurements with June 18, / 37

36 Conclusions Run 2 and Beyond projected luminosity LHC era HL-LHC era Run 1(a) Run 1(b) Run 2 Run 3 Run 4 Run ? 1 fb 1 2 fb 1 5 fb 1 15 fb 1 25 fb 1 5 fb 1 upgrade during LS 2, see -PUB replacement of RICH and tracking full software trigger, see -DR-16 current hardware readout at 1 MHz, upgrade at 4 MHz significantly more top statistics in the future double vector boson measurements possible Higgs in the not-so-near future? Ilten Measurements with June 18, / 37

37 Conclusions Final houghts has a diverse physics program, far beyond original design what would others like to see from? some (probably unreasonable) technical requests keep in mind fiducial definition for prefer tools that don t require file interfaces (i.e. LHEF) looking forward to Run 2 data hank you! Ilten Measurements with June 18, / 37