Electroweak Precision Physics from LEP to LHC and ILC

Transcription

1 Electroweak Precision Physics from LEP to LHC and ILC 50th Anniversary Particle and Nuclear Physics at KIT W. HOLLIK MAX-PLANCK-INSTITUT ÜR PHYSIK, MÜNCHEN

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3 undamental questions of particle physics: constituents of matter? structure of fundamental interactions? structure of vacuum? Current knowledge is based on the Standard Model

4 Outline Electroweak precision observables Standard Model Theory versus data Perspectives Extensions of the SM Supersymmetry Outlook

5 Standard Model the symmetry group SU(2) U(1) SU(3) C the principle of local gauge invariance fermion vector boson interaction vector boson self-interaction Higgs mechanism and Yukawa interactions masses M W, M Z, m fermion renormalizable quantum field theory accurate theoretical predictions detect deviations new physics? precise predictions required

6 e Elek.-Neutrino 3 e e Elektron 511 ke u Up-Quark 2 Me d Myon-Neutrino 190 ke Myon Me c Charm-Quark s 1.5 Ge Tau-Neutrino 18 Me Tauon 1777 Me t Top-Quark Ge b Leptons Quarks ermions (matter particles) Down-Quark 5 Me Strange-Quark 150 Me Bottom-Quark 4.5 Ge Photon 0 W W-Boson Ge H Z Z-Boson Ge g Gluon 0 Higgs-Boson 115 Ge Bosons (force particles)

7 example: QED precision tests of a theory at the quantum level Lamb shift: γ e e γ e + e g 2: e γ e γ nucleus a = 1 2 (g 2) a exp = (±1) a theo = (±8) B requirement: precise measurements precise predictions loop calculations

8 precision tests of the Standard Model through quantum loops sensitivity to heavy internal particles (X) Standard Model: X = Higgs, top precision observables µ lifetime: G Z observables: M Z, Γ Z, g, g A, sin 2 θ eff,... LEP 2, Tevatron, LHC: M W, m t

9 ½ Ñ ¾ Ñ ¾ Å ¾ Ï ½ ½ Õµ M W M Z correlation ÒØÓÒ Ó ÖÑ ÓÒ ØÒØ Ú ÑÙÓÒ ÐØÑ ¼ ½ ¾ Ñ Ñ ¾ ½¾ µ W ν µ e Õ É ÓÖÖØÓÒ Ò ÖÑ ÅÓÐ ν e G 2 = M 2 W πα ( 1 M 2 W /MZ) 2

10 with loop contributions 1-loop examples G 2 = M 2 W πα ( 1 M 2 W /MZ) 2 ØÓÔ ÕÙÖ Ø (1 + r) Ï Ï r : quantum correction r = r(m t,m H ) À Ó ÓÒ À Ï Ï determines W mass Ï Ù¹Ó ÓÒ Ð¹ÓÙÔÐÒ M W = M W (α,g,m Z,m t,m H ) Ï Ï Ï complete at 2-loop order full structure of SM

11 S S S S S S S S S S S S S S S S S S S S S S S S 2-loop examples

12 Z resonance cross section [nb] LEP: ALEPH DELPHI L3 OPAL data 2ν 3ν 4ν e + f 10 Z cms energy [Ge] e - f effective Z boson couplings with higher-order g,a g f gf + gf, gf A gf A + gf A effective ew mixing angle (for f = e): sin 2 θ eff = 1 ( ) 1 Re ge = κ 4 ga e ( 1 M2 W M 2 Z )

13 Ï Ï Ï Ï À Ï À µ Ï µ Ï Ï Ï Ï µ µ À À Ï 2-loop examples for Z couplings complete 2-loop calculation available for sin 2 θ eff

14 EW 2-loop calculations for r reitas, Hollik, Walter, Weiglein Awramik, Czakon Onishchenko, eretin EW 2-loop calculations for sin 2 θ eff Awramik, Czakon, reitas, Weiglein Awramik, Czakon, reitas Hollik, Meier, Uccirati universal terms beyond 2-loop order (EW and QCD) van der Bij, Chetyrkin, aisst, Jikia, Seidensticker aisst, Kühn Seidensticker, eretin Boughezal, Tausk, van der Bij Schröder, Steinhauser Chetyrkin, aisst, Kühn Chetyrkin, aisst, Kühn, Maierhofer, Sturm Boughezal, Czakon

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16 charge renormalization e + δe involves ÚÙÙÑ ÔÓÐÖÞØÓÒ ÔÓØÓÒ γ γ Π γ (M 2 Z) Π γ (0) α α(m Z ) = α 1 α α = α lept + α had, α lept = (3 loop) [Steinhauser] α had = ± significant source of parametric uncertainty

17 α had = α 3π M2 Z Re 4m 2 π ds R had (s ) s (s M 2 Z iǫ) 7 ρ,ω,φ Ψ s Υ s Burkhardt, Pietrzyk Rhad % s in Ge Bacci et al. Cosme et al. PLUTO CESR, DORIS MARK I CRYSTAL BALL MD-1 EPP-4 EPP-2M ND DM2 BES 1999 BES 2001 CMD KLOE % 5.9% 6% 1.4% rel. err. cont.

18 Lynn, Penso, erzegnassi, 87 Eidelman, Jegerlehner 95 Burkhardt, Pietrzyk 95 Martin, Zeppenfeld 95 Swartz 96 Alemany, Davier, Höcker 97 Davier, Höcker 97 Kühn, Steinhauser 98 Groote et al. 98 Erler 98 Davier, Höcker α had (M 2 ) ( 10 4 ) Z

19 ÄȽ»ËÄ ½¼ ÚÒØ»ÜÔÖÑÒØ ÄȽ ÄȾ Ï Ï µ Ï ÔÖ ½ ß ¾¼¼¼µ Ç ½¼ ÕÕ ¼ Ï Ð ÕÕ ¼ input from experiments ÜÔÖÑÒØ ½ ß ½µ ÌÚØÖÓÒ ÔÔµ ÕÕ ¼ ØØ Ø Ï ÐÓÛ¹ÒÖÝ ÜÔÖÑÒØ Ý Æ ØØÖÒ ØÓÑ ÔÖØÝ ØØÖÒ ÚÓÐØÓÒ µ

20 ¾¾ ¼¼¼¾ ¼¼± Î ¾ ÐÔØ Ò Theory versus Data experimental results (selection) Å Î ½½ ¼¼¼¾½ ¼¼¼¾± ¼¾ ½ ¼¼¼¼½ ¼¼± «Î ¼ ¼¼¾ ¼¼± ÅÏ ÑØ Î ½ ½ ½ ¼± Î ¾ ½½ ½µ½¼ ¼¼¼½± quantum effects at least one order of magnitude larger than experimental uncertainties

21 LEP Electroweak Working Group July LEP2 and Tevatron (prel.) LEP1 and SLD 68% CL m W [Ge] α m H [Ge] m t [Ge]

22 LEP Electroweak Working Group March 2009 m t = ± 1.3 Ge m H = Ge sin 2 θ lept eff m H α m t 68% CL Γ ll [Me]

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24 development of precision ± ± ± average ± m Z [Ge]

25 importance of two-loop calculations sin 2 Θeff loop QCDlead.3loop 2loop M H Ge

26 Ï Ï W-pair production Ï Ï σ WW (pb) 30 LEP PRELIMINARY 17/02/ YSWW/RacoonWW no ZWW vertex (Gentle) only ν e exchange (Gentle) s (Ge)

27 Measurement it O meas O fit /σ meas α (5) had (m Z ) ± m Z [Ge] ± Γ Z [Ge] ± σ 0 had [nb] ± R l ± A 0,l fb ± A l (P τ ) ± R b ± R c ± A 0,b fb ± A 0,c fb ± A b ± A c ± A l (SLD) ± sin 2 θ lept eff (Q fb ) ± m W [Ge] ± Γ W [Ge] ± m t [Ge] ± March

28 6 5 4 July 2010 Theory uncertainty α had = α (5) ± ± incl. low Q 2 data m Limit = 158 Ge blueband: theory uncertainty χ Excluded Preliminary M H [Ge] Precision Calculations at the Z Resonance CERN [Bardin, Hollik, Passarino (eds.)] M H < 157 Ge (95%C.L.) with direct search M H > 114 Ge: M H < 186 Ge (95%C.L.)

29 experimental search LEP: À excluded M H < 114 Ge Tevatron: t t t H W, Z H W, Z

30 Tevatron Run II Preliminary, <L> = 5.9 fb -1 95% CL Limit/SM 10 1 LEP Exclusion SM=1 Expected Observed ±1σ Expected ±2σ Expected Tevatron Exclusion Tevatron Exclusion July 19, m H (Ge/c 2 ) high mass 95% CL exclusion: 158 < m H < 175 Ge dominated by gg H WW channel low mass sensitivity mainly by qq WH lν b b

31 Next experiments at high energy accelerators

32 Next experiments at high energy accelerators

33 Perspectives 2009: The Large Hadron Collider uture: e + e Linear Collider

34 Higgs production at the LHC ÐÙÓÒ Ù ÓÒ À ÚØÓÖ Ó ÓÒ Ù ÓÒ ÕÕ ÕÕÀ À ØÖÐÙÒ ÕÕ ¼ Î À Ø ØÀ Àµ ÔÖÓÙØÓÒ Å À Ñ Ø ½ Î ÅÊËÌ»ÆÄÇ ½¼¼ À ÔÔ À µ Ô À Ô ½ ÌÎ Õ ½¼ Ï ÀÕÕ À Ï Õ Ï À À Ø ØÀ ½ À Ï Ï ¼º½ ½¼¼ ½¼¼¼ Ø µ Õ Ø µ Î À À Ø µ Õ Ø µ

35 Higgs production at the LHC ÐÙÓÒ Ù ÓÒ À À gluon-gluon fusion: NNLO QCD [Harlander, Kilgore] NL EW [Degrassi, Maltoni] ÚØÓÖ Ó ÓÒ Ù ÓÒ ÕÕ ÕÕÀ Õ Ï À WW (ZZ) fusion: NLO QCD [igy, Oleari, Zeppenfeld] Ï Õ À ØÖÐÙÒ ÕÕ ¼ Î À À Higgs-strahlung processes: NNLO QCD + NLO EW [Brein et al.] Ï Ï Ø ØÀ Àµ ÔÖÓÙØÓÒ Ø µ Õ À Ø µ À radiation from heavy quarks: NLO QCD [Beenakker et al., Dawson et al.] NLO EW [Denner et al.] Ø µ Õ Ø µ

36 expected precision error for LEP/Tev Tev/LHC ILC ILC/GigaZ M W [Me] sin 2 θ eff m top [Ge] M Higgs [Ge] δm Z = 2.1 Me (LEP) δg /G = (µ lifetime) GigaZ MegaW 10 9 Z bosons 10 6 W bosons

37 after the Higgs boson mass is measured presently 68% CL: LEP/SLC/Tevatron LHC/LC sin 2 θ eff M H = 180 Ge 150 Ge α m t GigaZ 120 Ge M W [Ge] [Erler, Heinemeyer, Hollik, Weiglein, Zerwas]

38 Theoretical bounds on Higgs boson mass from perturbativity upper bound unitarity upper bound triviality (Landau pole) upper bound vacuum stability lower bound

39 combined effects, RGE in two-loop order: dλ dt = 1 16π 2 ( 12λ 2 3g 4 t + 6λg 2 t + )

40 Standard Model Higgs: λh 4 term ad hoc Higgs boson mass: free parameter λ no a-priori reason for a light Higgs boson the question for New Physics

41 ÝÓÒ Ø ËØÒÖ ÅÓÐ ÙÖØÖ Ù ØÖÙØÙÖ ÐÑÒØÖÝ ÙÒÑÒØÐ Ð «Ø ÖÓÑ ÒÛ ÒØÖØÓÒ ÖÑÒ Û ØÖÓÒ ÒØÖØÓÒ ÖÒ ÍÒ ÌÓÖ ÒÛ ØÖÓÒ ÝÒÑ ÒÛ ÝÑÑØÖÝ Ø ÒÖÝ Ð ÙÔÖ ÝÑÑØÖÝ

42 supersymmetry in particle physics Julius Wess Institut für Theoretische Physik Karlsruhe, supersymmetric relativistic QT Wess, Zumino 1974 SUSY Standard Model

43 gauge coupling unification stabilization of the electroweak scale dark matter candidate (lightest SUSY particle) lightest Higgs boson h 0 < 135 Ge physical Higgs bosons: h 0, H 0, A 0, H ±

44 Standard Model Higgs: = µ 2 Φ 2 + λφ 4, Φ = v + H λh 4 term ad hoc Higgs boson mass: free parameter λ no a-priori reason for a light Higgs boson SUSY Standard Model: light Higgs is natural H 2 = H+ 2 v 2 + H 0 2, H 1 = v 1 + H 0 1 H 1 couples to u couples to d SUSY gauge interaction self coupling remains weak H 4 terms 2 doublets: minimal model, MSSM

45 «Ø Spectrum of Higgs bosons in the MSSM (example) m h max scen., tanβ = 5 h H A H +- M Higgs [Ge] eynhiggs M A [Ge] large M A : h 0 like SM Higgs boson decoupling regime m 0 h strongly influenced by quantum effects, e.g. q q H H H H q q

46 1-loop: complete 2-loop: QCD corrections α s α t, α s α b Yukawa corrections αt,b 2 theoretical uncertainty: δm h 3 Ge public code eynhiggs latest version: eynhiggs2.7 arxiv: m h [Ge] tree-level full 1L 2L (eynhiggs) X t [Ge] ØÒ Å É Å ½ ÌÎ Ñ ¼¼ Î Ø ØÓÔ¹ ÕÙÖ ÑÜÒ ÔÖÑØÖ X t = A t µ cot β Ñ ¼ ÔÖØÓÒ Ø «ÖÒØ ÐÚÐ Ó ÙÖÝ

47 eynhiggs the Swiss Army Knife for Higgs Physics T. Hahn, S. Heinemeyer, W. Hollik, H. Rzehak, G. Weiglein eynhiggs, the Swiss Army Knife for Higgs Physics

48 3-loop contributions α 2 s α t [Harlander, Kant, Mihaila, Steinhauser] M h (i) (Ge) Me µ = M t M SUSY (Ge) 1-loop 2-loop 3-loop 500Me

49 135 m h exp m t = 175 Ge, tanβ = m h [Ge] theory prediction for m h δm t exp = 2.0 Ge δm t exp = 1.0 Ge δm t exp = 0.1 Ge M A [Ge] dependent on all SUSY particles and masses/mixings through Higgs self-energies

50 indirect access to SUSY particles through quantum loops X = Higgs bosons, SUSY particles µ lifetime: M W M Z, G Z observables: g, g A, sin 2 θ eff, Γ Z, M Z,... 2-loop terms O(αα s, α 2 t, α2 b, α tα b ) and complex parameters [Heinemeyer, WH, Stöckinger, A. Weber, Weiglein 06] [Heinemeyer, WH, A. Weber, Weiglein 07]

51 M W M Z correlation µ W ν µ e ν e G 2 = M 2 W πα ( 1 M 2 W /MZ) 2 (1 + r) r : quantum correction, r = r(m t,x SUSY ) M W = M W (α,g,m Z,m t,x SUSY ) X SUSY = set of non-standard model parameters

52 Z resonance cross section [nb] LEP: ALEPH DELPHI L3 OPAL data 2ν 3ν 4ν e + f 10 Z cms energy [Ge] e - f effective Z boson couplings g f gf + gf, gf A gf A + gf A with higher order contributions g f,a (m t,x SUSY ) sin 2 θ eff = 1 4 ( ) 1 Re ge ga e = κ ( 1 M2 W M 2 Z )

53 experimental errors 68% CL: LEP2/Tevatron (today) Tevatron/LHC ILC/GigaZ light SUSY experimental errors 68% CL: LEP2/Tevatron (today) Tevatron/LHC ILC/GigaZ M W [Ge] M H = 114 Ge SM M H = 400 Ge SM MSSM both models MSSM heavy SUSY Heinemeyer, Hollik, Stockinger, Weber, Weiglein m t [Ge] sin 2 θ eff heavy SUSY MSSM light SUSY SM MSSM both models M H = 400 Ge SM M H = 114 Ge Heinemeyer, Hollik, Weber, Weiglein m t [Ge]

54 A 0,l fb ± A l (P τ ) ± A l (SLD) ± A 0,b fb ± A 0,c fb ± Q had fb ± Average ± χ 2 /d.o.f.: 11.8 / 5 M H [Ge] 10 2 α had = ± α (5) m t = ± 2.9 Ge sin 2 θ lept eff

55 experimental errors 68% CL: experimental errors 68% CL: m t = Ge A LR (SLD): sin 2 θ eff = ± A B (LEP): sin 2 θ eff = ± m t = Ge sin 2 θ eff M H = Ge sin 2 θ eff M H = Ge SM MSSM both models Heinemeyer, Hollik, Weber, Weiglein M W [Ge] SM MSSM both models Heinemeyer, Hollik, Weber, Weiglein M W [Ge]

56 Anomalous g-factor of the muon HMNT (06) JN (09) Davier et al, τ (09) Davier et al, e + w/o BaBar (09) e w/ BaBar (09) HLMNT (09) BNL experiment BNL (new from shift in λ) a µ SM Hagiwara,Martin,Nomura,Teubner 2010 e + e data based SM prediction: almost 4 σ below exp. value theory uncertainty from hadronic vacuum polarization

57 g 2 with supersymmetry new contributions from virtual SUSY partners of µ, ν µ and of W ±, Z µ χ i ν µ µ µ µ a χ0 j µ γ χ i γ µ b extra terms + α π m 2 µ M 2 SUSY v2 v 1 can provide missing contribution for M SUSY = Ge 2-loop calculation [Heinemeyer, Stöckinger,...]

58 ariable Measurement it (5) (M had Z α ) ± MZ [Ge] ± ΓZ [Ge] ± had σ [nb] ± R ± l 0,l B A ± Al (P ) τ ± Rb ± Rc ± ,b AB ± ,c AB ± A 0.923± b Ac ± Al (SLD) ± l sin θ (Q ) eff B ± M [Ge] W ± mt [Ge] ± BR(b sγ) 1.13± meas fit meas O -O /σ BR( B s µµ)[ 10 ] < N/A (upper limit) -9 CMSSM δa µ [ 10 ] 2.95 ± Ωh 0.113± ariable Measurement it (5) (M had Z α ) ± MZ [Ge] ± ΓZ [Ge] ± had σ [nb] ± R ± l 0,l B A ± Al (P ) τ ± Rb ± Rc ± ,b B 0,c B A ± A ± A 0.923± b Standard Model Ac ± Al (SLD) ± l sin θ (Q ) eff B ± M [Ge] W ± mt [Ge] ± Γ [Ge] W ± meas fit meas O -O /σ global fit in the constrained MSSM including data from g 2, B physics, and cosmic relic density [O. Buchmueller,..., Weber, Weiglein, arxiv: ]

59 CMSSM SM χ 2 2 χ LEP excluded Theoretically inaccessible LEP excluded CMSSM M h [Ge] M Higgs [Ge] M h = Ge

60 g~ ~ t 2 q~ ~ b ~ t A,H ± H 0 χ, χ 4 ± 2 χ ν ~ l L,τ 2 0 χ, χ 2 ± h ~ l R,τ 1 χ best fit particle spectrum

61 Conclusions Electroweak precision physics sensitive to quantum structure constraints on unknown parameters precision tests of the Standard Model have established the SM as a quantum field theory MSSM is competitive to the SM global fits of similar quality (even better) natural: light Higgs boson h 0 future experiments at colliders discovery of Higgs and SUSY at LHC (?) precision studies at e + e Linear Collider