Precision Electroweak Measurements at the Tevatron The W mass @ Tevatron Effec9ve weak mixing angle The Top Mass @ Tevatron Iain Bertram, Lancaster University for the D0 Collabora9on DIS 2017-6 April 2017 1
Mo9va9ons Consistency tests of electroweak symmetry breaking mechanism [GeV] M W 80.5 80.48 80.46 80.44 68% and 95% CL contours direct M and sin 2 (θ f ) measurements W eff fit w/o M, sin 2 (θ f ) and Z widths measurements W W 2 eff f eff f eff fit w/o M, sin (θ ) and M fit w/o M, sin (θ ), M W 2 2 f eff sin (θ ) LEP+SLC ± 1σ measurements H and Z widths measurements H [GeV] M W 80.5 80.45 68% and 95% CL contours fit w/o M fit w/o M direct M and m t measurements W, m and M W t and m t W measurements H measurements m t world comb. ± 1σ m t = 173.34 GeV σ = 0.76 GeV σ = 0.76 0.50 theo GeV 80.42 80.4 80.38 80.4 80.35 M W M W world comb. ± 1σ = 80.385 ± 0.015 GeV 80.36 80.34 80.32 M W world comb. ± 1σ G fitter SM Jul 14 80.3 80.25 M H = 50 GeV M H = 125.14 GeV M H = 300 GeV M H = 600 GeV G fitter SM Jul 14 0.2308 0.231 0.2312 0.2314 0.2316 0.2318 0.232 0.2322 sin 2 (θ l ) eff 140 150 160 170 180 190 m t GFiQer results 2016 Over-constrained: 3 free parameters in the SM are constrained by 7 experimental measurements. em,g F,M Z, M W, sin 2 W, m top,m H [GeV] 2
Tevatron @ Fermilab Mul9-purpose, high acceptance, well understood detectors. L dt~ 10 W ¹ D0 η = 0 η = 1 [m] Muon Scintillators CDF 5 Muon Chambers η = 2 p 0 Shielding Calorimeter η = 3 p Toroid 5 10 5 0 5 10 3
The W mass @ Tevatron Strategy: Analyse the p l distribu9ons in W lν (l=e/μ) channels T, /E T,m l T Likelihood fits of M W -parameterized simula9on templates Lepton E/p scale and recoil calibra9on with Z ll data Results Phys. Rev. D 052018 (2013) M W (MeV/c 2 ) CDF (2.2 W,μ&e) 80 387 ± 12 ± 15 D0 (5.3 W, e) 80 375 ± 11 ± 20 Dominant systema9c are the lepton E/p scale and PDFs. Tevatron results are combined using BLUE M W = 80387 ± 16MeV/c 2 Mass of the W Boson Measurement M W [MeV] CDF 1988995 (107 pb ) 80432 ± 79 D0 1992995 (95 pb ) 80478 ± 83 CDF 2002-2007 (2.2 fb ) 80387 ± 19 D0 2002-2009 (5.3 fb ) 80376 ± 23 Tevatron 2012 80387 ± 16 LEP 80376 ± 33 World average 80385 ± 15 Consistent with the latest ATLAS result of 80370±19 MeV arxiv:1701.07240 80200 80400 80600 M W [MeV] CDF and D0 are working on finalising measurements with the full data set. 4
Effec9ve weak mixing angle The forward-backward asymmetry A W arises from the interference of the vector and axial vector couplings. gh order corrections factorized as enhanced Born approximation(eba) Ø The effective mixing angle: converged to leptonic one g f V f A = g = I I f 3 f 3 2Q f sin 2 θw 2 sin θw Convert sin 2 θ ll eff to sin 2 θ W using conversion factor calculated using ZFiQer (depends on well known M Z ): Re(κ) ~ 1.037 = M M 2 W 2 Z ( on-shell ) 2θ Lept Re[ κ (M )] 2 sin θ Z sin eff = l ( effective, Zfitter) Can be directly measured via Parity-violating observables at Z-pole W (modified Resbos) 5
Effec9ve weak mixing angle The best current measurements differ by 3.2σ LEP b-quark A 0,b W SLD beam LR-polariza9on A lr The LEP/SLD Average 0.23153 ± 0.00016 6
Weak mixing angle @ the Tevatron Measure background-subtracted A W as func9on of invariant mass in Collins- Soper frame l + l - A fb = N(cos > 0) N(cos < 0) N(cos > 0) + N(cos < 0) cos = 2(p + l p l p l p + l ) q m(l l) m 2 (l l)+p 2 T (l l) p ± l = p 0 ± p 3 7
Previous Results χ 2 fits between data A FB and MC templates for a series of different Pythia values of sin 2 θ W CDF Zµµ 9fb D0 Zee 9.7fb CDF Zee 9fb PRD 89(2014)072005 PRL115(2015)041801 PRD 93(2016)112016 sin 2 θ W ± stat. ± syst. ± PDF Total uncertainty CDF Zµµ 9fb 0.2315 ± 0.0009 ± 0.0002 ± 0.0004 ±0.0010 DØ Zee 9.7fb 0.23147 ± 0.00043 ± 0.00008 ± 0.00017 ±0.00047 CDF Zee 9fb 0.23248 ± 0.00049 ± 0.00004 ± 0.00019 ±0.00053 8
.5 0 Previous Tevatron Combina9on Combina9on of CDF Zμμ+Zee and D0 Zee results Using ZFITTER and NNPDF3.0 sin 2 lept e LEP and SLD: Z-pole 0,b LEP and SLD: A FB SLD: A l CMS µµ 1 fb ATLAS ee+µµ 5 fb LHCb µµ 3 fb CDF µµ 9 fb CDF ee 9 fb CDF ee+µµ 9 fb D0 ee 10 fb August 2016: preliminary TeV combined: CDF+D0 August 2016: preliminary 0.226 0.228 0.23 0.232 0.234 2 sin lept θ eff =0.23179 ± 0.00030 ± 0.00017 0.23149±0.00016 0.23221±0.00029 0.23098±0.00026 0.2287±0.0032 0.2308±0.0012 0.23142±0.00107 0.2315±0.0010 0.23248±0.00053 0.23221±0.00046 0.23137±0.00047 0.23179±0.00035 sin 2 lept e Translate into M W Tevatron from sin 2 θ W =0.23179 ± 0.00035 M W = 80351 ± 18 MeV/c 2 Compare with Tevatron and LEP direct measurements M W = 80385 ± 15 MeV/c 2 FERMILAB-CONF6-295-E 9
Last channel @ Tevatron : New: D0 Zμμ 8.6 W Zμμ events, p T >15GeV/c, η <1.8; opposite charge, 74 < M μμ < 110 GeV/c 2 Modified Resbos + NNPDF3.0 The D0 Zμμ result is less precise than Zee due to the more central muon acceptance and the less precise muon momentum measurement. We reweight the MC to data separately as a func9on of eta for each muon charge and solenoid polarity so as to correct for residual mis-alignments 10
MC Data Comparison Check agreement in mul9ple kinema9c distribu9ons Muon p T /η, and di-muon p T /η/m/cosθ * distribu9on Good agreement We fit the data to templates for varying values of the Born level sin 2 θ W B in Pythia in a mass region of 74<M μμ <110 GeV sin 2 B W =0.22994 ± 0.00059 (stat) ± 0.00011 (syst) ± 0.00027 (pdf) = 0.22994 ± 0.00066 11
Systema9cs Dominated by uncertainty due to the PDF and modelling the background. sin 2 W B 0.22994 Statistical uncertainty 0.00059 Systematic uncertainties Momentum calibration 0.00002 Momentum resolution 0.00004 Background 0.00010 E ciencies 0.00001 Total systematic 0.00011 PDF 0.00027 Total 0.00066 12
Result sin 2 B W =0.22994 ± 0.00059 (stat) ± 0.00011 (syst) ± 0.00027 (pdf) = 0.22994 ± 0.00066 Convert sin 2 θ W B to sin 2 θ eff ll using comparison of LO Pythia and NLO Resbos: sin 2 θ eff ll = sin 2 θ W B + 0.00008 sin 2 l e =0.23002 ± 0.00066 ± This is converted to the on-shell normalisa9on for sin 2 θ W using ZFiQer sin 2 W (on-shell) = 0.22181 ± 0.0064 corresponding to ± M W = 80441 ± 33 MeV/c 2 D0 Note 6497-CONF D0 s Zμμ and Zee results agree to 1.4σ (when referred to the same PDF set). 13
Direct Top Mass from D0 Full D0 combina9on of Run1 0.1 W and Run2 9.7 W results Systema9c uncertain9es and correla9ons among channels have been taken into account m t = 174.9 ± 0.75 GeV/c 2 D0 combined values (GeV) top quark mass 174.95 In situ light-jet calibration 0.41 Response to b, q, andg jets 0.16 Model for b jets 0.09 Light-jet response 0.21 Out-of-cone correction < 0.01 Offset < 0.01 Jet modeling 0.07 Multiple interaction model 0.06 b tag modeling 0.10 Lepton modeling 0.01 Signal modeling 0.35 Background from theory 0.06 Background based on data 0.09 Calibration method 0.07 Systematic uncertainty 0.64 Statistical uncertainty 0.40 Total uncertainty 0.75 arxiv:1703.06994 [hep-ex] SubmiQed to PRD 14
Top pole mass from differen9al cross sec9ons Top quark momentum, t t invariant mass distribu9ons, etc. are sensi9ve to the top quark mass Expect improvement vs extrac9on from total cross-sec9on eg. Phys. Rev. D 94, 092004 (2016) Use the D0 lepton+jets measurement: Phys. Rev. D 90, 092006 (2014) Compare differen9al distribu9ons to NNLO QCD calcula9on of TOP++ using the pole mass: Czakon, Fiedler, Heymes and Mitov, JHEP 1605, 034 (2016) See D Heymes talk on Tuesday 15
Top pole mass from differen9al cross sec9ons NNLO QCD scale uncertain9es < 5% for p T top c.f. 10% maximum for m(q) } { } { 16
Top pole mass from differen9al cross sec9ons Use χ 2 fit to measure the mass Include full 2-D correla9on matrix in m(q), p T top D0CONF 6473 m t = 169.1 ± 1.4 (theo) ± 2.2 (exp) GeV/c 2 Precision: 1.5% ~ 25% improvement over using inclusive XS 17
Summary W Mass Current Tevatron combina9on is 80387 ± 16 MeV Analysis of full data sample is ongoing. Weak Mixing Angle Preliminary Tevatron combina9on of 0.23179 ± 0.00035 using CDF Z(ee/μμ) and D0 Z(ee) NEW preliminary result of 0.23002±0.00066 with D0 Z(μμ) measurement Once the D0 Z(μμ) result is finalised the full Tevatron combina9on will be completed. Will make a significant contribu9on to improving the world average. Top Mass New D0 combina9on of all direct measurements from Run I and Run II. New D0 preliminary measurement of top quark pole mass using dσ/dp T and dσ/m Q. 18