The global Standard Model fit to electroweak precision data

Transcription

1 XLIV th Rencntres de Mrind n QCD and High Energy Interactins March 14 th March 21 st 2009, La Thuile, Italy Paper accepted fr publicatin in EPJ C (arxiv: ) The glbal Standard Mdel fit t electrweak precisin data Fr the Gfitter Grup *) Jörg Stelzer (DESY, Germany) *) M.Baak (CERN), H.Flächer (CERN), M. Gebel (Univ. Hamburg, DESY), J.Haller (Univ. Hamburg), ) M.Baak (CERN), H.Flächer (CERN), M. Gebel (Univ. Hamburg, DESY), J.Haller (Univ. Hamburg), A. Höcker (CERN), D. Ludwig (Univ. Hamburg), K. Mönig (DESY), M.Schtt (CERN), J. S.

2 The Gfitter Prject Gfitter: A Generic Fitter Prject fr HEP Mdel ltesting prvide a flexible framewrk fr invlved fitting prblems in the LHC era Based n the ROOT framewrk (math lib, drawing) Physics: plug in packages GSM: Standard Mdel fit t the electrweak precisin data G2HDM: Tw Higgs Dublet Mdel extensin f the SM GOBLIQUE: Oblique parameters S,T, U in the glbal EW fit presented by M. Gebel at Mrind EW Advanced statistical analyses methds: e.g. parameter scans, MC ty analyses, p value, gdness f fit, etc. fllws frequentist apprach Cnsistent treatment f statistical, systematic and theretical errrs, crrelatins, and inter parameter dependencies theretical uncertainties: Rfit prescriptin [CKM fitter, EPJ C21, 225 (2002)] thery uncertainties included in χ 2 estimatr with flat likelihd in allwed ranges Revisiting the Glbal EW Fit with Gfitter Mrind 17th March

3 The Electrweak Fit SM predictins f electrweak precisin bservables Cmplete re implementatin f electrweak thery Excellent agreement with Zfitter State f the art calculatins in the OMS scheme M W and sin 2 θ f eff: tw lp and leading beynd tw lp crrectin [M. Awramik et al., Phys. Rev D69, (2004 and ref.][m. Awramik et al., JHEP 11, 048 (2006) and refs.] Radiatr functins: N 3 LO f the massless QCD Adler functin Tw versins f fits [P.A. Baikv et al., Phys. Rev. Lett. 101 (2008) ] Standard fit : all data except results frm the direct Higgs searches Cmplete fit : : all data including results frmdirect Higgs searches at LEP and Tevatrn [ADLO Phys.Lett. B565, 61 (2003)] [CDF+D0: arxiv: ] [CDF+D0: arxiv: ] Revisiting the Glbal EW Fit with Gfitter Mrind 17th March

4 The Electrweak Fit Experimental Input Z ple precisin crss sectinsectin and asymmetry measurements frm LEP/SLC: M Z, Γ Z hadrnic ple x sectin σ 0 had leptnic rati R 0 l the hadrnic ratis R 0 c, R 0 b includes SLD measurements FB asymmetries l,b,c (final state angular distributin) LR asymmetries ti SLC A l,a b,a c (IS plarizatin), LEP A l (τ plarizatin) [ADLO +SLD, Phys. Rept. 427, 257 (2006)] M W and Γ W frm LEP/Tevatrn [ADLO,CDF+D0: arxiv: ] m c, m b wrld averages m t latesttevatrn average [PDG, J. Phys. G33,1 (2006)] [arxivx: [hep ex]] ex]] Δα had (5) (M Z2 ) including α s dependency [arxivx: [hep ex]] M H in cmplete fit: likelihd ratis frm Tevatrn Revisiting the Glbal EW Fit with Gfitter Mrind 17th March

5 SM Fit [ADLO: Phys. Lett. B565, 61 (2003)] Free fit parameters: M Z, M H, m t, Δα (5) had (M Z2 ), α S (M Z2 ), m c, m b Δα (5) had (M Z2 ) flating instead f α Other cntributins: tib ti leptnic and t quark (well llk knwn) Fixed (wrld average): G F and masses f leptns and light quarks Wllk Well knwn and/r negligible ibl effect [CDF+D0: arxiv: ] Parameters fr theretical uncertainties M 5 W : δm W =4GeV; sin 2 θ l eff: δsin 2 θ l eff = electrweak frm factrs ρ f Z, κ f Z: negligible effect LEP/Tevatrn direct SM Higgs searches interpret 2lnQ(M H ) as measurement transfrm 1 sided int 2 sided CL fit cntributin δχ 2 =2[Erf 1 (1 CL s+b tw sided )] 2 1 CL s+b tw sided CL s+b 1 Fit cntributin frm direct Higgs searches Revisiting the Glbal EW Fit with Gfitter Mrind 17th March

6 SM Fit Results Mdel Test Gdness f fit: standard fit: χ 2 min/n df = 16.4/13 cmplete fit: χ 2 min/n df = 18.0/14 p value evaluated using ty MC Cmplete fit Prbability fr wrngly gyrejecting SM: (21.7±0.4)% N indicatin f new physics Pull values f cmplete fit: largest χ 2 min cntributin frm A FB f b quark 2.6σ Small cntributins frm M Z, Δα had (M Z ), m c, m b indicate that their input accuracies exceed fit requirements Cmplete fit results in backup slides Revisiting the Glbal EW Fit with Gfitter Mrind 17th March

7 Checking α S in N 3 LO α S frm cmplete fit ( ) = ± α S M Z [M. Davier et al., arxiv: ] 0979] 4 lp RGE evlutin f α s (μ) and measurements first errr is experimental fit errr secnd errr due t truncated pqcd expansin: incl. variatin f renrm. scale frm M Z /2 t 2M Z and mass less terms f rder/beynd α S5 (M Z ) and massive terms f rder/beynd d α 4 S4 (M Z ) excellent agreement with recent N 3 LO result frm τ decay 2 α S ( M Z ) = ± Sensitive test t RGE evlutin ver tw rders f magnitude Revisiting the Glbal EW Fit with Gfitter Mrind 17th March

8 Higgs Mass Cnstraint M H frm standard dfit: Central value ±1σ: M H = 2σ interval: [39, 155] GeV 3σ interval: [26, 209] GeV GeV Standard fit Green band due t Rfit treatment, fixed thery errrs lead t larger χ 2 M H frm cmplete fit: H Central value ±1σ: M H 2σ interval: [114, 145] GeV = GeV 3σ interval: [113, 168] and [180, 225] GeV Cmplete fit Tevatrn LEP 2.4 fb 1 3 fb 1 Revisiting the Glbal EW Fit with Gfitter Mrind 17th March

9 Higgs Mass Cnstraint Crrelatin cefficients between the free fit parameters in the standard fit. Knwn tensin between A l (SLD) and A 0,b FB Fitted value fr M H when remving all but the indicated bservable frm the fit Cmpatibility test (ty analysis): Shift in χ 2 min when least cmpatible measurement (here A 0,b FB ) remved: Δχ 2 min = 8.0 Generate ty arund fitted values, and repeat prcedure > Δχ 2 min distributin (1.4±0.1)% f ty experiments exceed Δχ 2 min = 8.0 ( 2.5σ ) Revisiting the Glbal EW Fit with Gfitter Mrind 17th March

10 Tp Quark Mass Tp mass cmparisn: Standard fit: 10. m t = GeV = Cmplete fit: m t.2 9. GeV Tevatrn measurement: m t =172.4 ± 1. 2GeV (ld) New Tevatrn measurement 2 D scans: Standard fit (excluding M W and m t) agrees with experimental values Results frm Higgs searches reduce allwed parameter space significantly Gd prbe f SM if M H is measured at LHC/ILC Revisiting the Glbal EW Fit with Gfitter Mrind 17th March

11 Prspects fr LHC and ILC Fit predictin f M 2 H and α S (M Z2 ) in light f LHC, ILC (GigaZ ptin) Cnservative estimates n imprvement n σ(m W ), σ(m t ), σ(sin 2 θ l eff ff) ), and σ(r l0 ) Anticipate imprved calculatin f Δα (5) had (M Z2 ) Requires σ(σ had ) 1% belw J/ψ [F. Jegerlehner, hep ph/ ] Crss sectin measurements by BABAR (ISR based) and BESIII shuld imprve Δα had (M Z ) Imprvement f M H predictin Assume M H =120GeV by adjusting central values f all bservables Brad minima: Rfit treatment f theretical uncertainties Cnfrnt with direct measurement GigaZ: Gga sg significant imprvement pe e fr α S (M Z2 ) and M H wing t smaller σ(r l0 ) Input values taken frm: [CMS, Physics TDR (2006)][A. Djuadi et al., arxiv: ] [I. Brjanvic, EPJ C39S2, 63 (2005)][S. Haywd et al., hep ph/ ] [ATLAS, Physics TDR (1999)][R. Hawkings, K. Mönig, EPJ direct C1, 8 (1999)] [A. H. Hang et al., EPJ direct C2, 1 (2000)] [M. Winter, LC PHSM ] input Revisiting the Glbal EW Fit with Gfitter Mrind 17th March

12 SM Extensin Tw Higgs Dublet Mdel Type II Mdel: dl Higgs fermin cupling: up and dwn type fermins cuple t different dublets 6 free parameters: M H±, M A0, M H0, M h, tanβ, α bservable input value S far: bservables sensitive t H ± M H±, tanβ Hadrnic Z width rati: R 0 b Semileptnic B decay: B Dτν / Deν H± β R b ± BR (B >X s γ) (3.52±0.23±0.09) 10 4 BR (B >τν) (1.51±0.33) 10 4 BR (B >μν) < at 90% CL BR (K >μν)/ BR(p >μν) 1.004±0.007 BR(B >Dτν)/ BR(B >Deν) 0.416±0.117±0.052 Radiative B and leptnic mesn decays: B X s sγ, B μν / τν,, K μν / π μν R 0 b: sensitive t small tanβ nly B >X S γ: M H± >220 fr tanβ>1 B >τν: strngest cnstraint Revisiting the Glbal EW Fit with Gfitter Mrind 17th March

13 2HDM Cmbined Fit Cmbined dfit: Exclusin area depends n assumptin n number f degrees f freedm n df =1 where single cnstraint dminates n df =2 where several bservable cntribute MC ty study t determine exclusin area Exclude at 95% CL Small tanβ M H± < 240 GeV fr all tanβ M H± < 780 GeV fr tanβ=70 Cmbined limit nt necessarily strnger than single cnstraint due t increasing n df Revisiting the Glbal EW Fit with Gfitter Mrind 17th March

14 Fitting with the New Tevatrn Results New M W mass by D0: M W = ± ± ± GeV c stat exp crr 2 Tevatrn average nt yet released, use preliminary wrld average: M W = ± GeV/c 2 (errr was GeV/c 2 befre) New tp mass frm Tevatrn (previus 172.4±1.2 GeV/c 2 ) m t = ± 0.6 ± 1.11 GeV c = stat sys 2 New Higgs search limits: exclusin between 160 and 170 GeV/c 2 Revisiting the Glbal EW Fit with Gfitter Mrind 17th March

15 New Higgs Mass Cnstraints M H frm standard dfit: Fit input fr M W is ur preliminary average! Central value ±1σ: + 30 M H = GeV 2σ and 3σ interval: [41, 158] and [28, 211] GeV + (Previusly: = GeV ) M H 23 Shift f mean and intervals up by abut 3GeV Psitive crrelatin between M H and m t Cmplete fit: input frm direct searches Fitneeds CL s+b asinput (we lk fr agreement with SM), Higgs searches use CL s (fr exclusin limits) which is mre cnservative We are in cntact with the Tevatrn New Phenmena and Higgs WG (TEVNPHWG) fr these numbers Expect significantly tighter limits n M H Revisiting the Glbal EW Fit with Gfitter Mrind 17th March

16 Cnclusins and Prspects (ty MC simulatin) p value f the standard fit versus true M H (nt with the latest Tevatrn results) Cntinue t update Gfitter fr SM and 2HDM fits Next steps: Lk further beynd the SM Implementatin ti f blique parameters and Littlest Higgs Mdelt l presented at Mrind EW Revisiting the Glbal EW Fit with Gfitter Mrind 17th March

17 NUMERICAL RESULTS Revisiting the Glbal EW Fit with Gfitter Mrind 17th March

18 Fit results (I) withut New Tevatrn Results Revisiting the Glbal EW Fit with Gfitter Mrind 17th March

19 Fit results (II) withut New Tevatrn Results Revisiting the Glbal EW Fit with Gfitter Mrind 17th March

20 Fit results (I) with New Tevatrn W and Tp Mass Revisiting the Glbal EW Fit with Gfitter Mrind 17th March

21 Fit results (II) with New Tevatrn W and Tp Mass Revisiting the Glbal EW Fit with Gfitter Mrind 17th March