Magnetic moment (g 2) µ and beyond the Standard Model physics

Transcription

1 Magnetic moment (g 2) µ and beyond the Standard Model physics TU Dresden Lepton Moments Symposium, Cape Cod, July 2014

2 Discrepancy SM prediction too low by (28.7±8.0) Note: discrepancy twice as large as a SM,weak µ ( ) but we expect: aµ NP aµ SM,weak MW 2 M NP couplings

3 Outline 1 Impact on New Physics in general Complementary Model dependent 2 Dark photon 3 SUSY Can explain the deviation tension with LHC data? details, new results Complementarity

4 Outline 1 Impact on New Physics in general Complementary Model dependent 2 Dark photon 3 SUSY Can explain the deviation tension with LHC data? details, new results Complementarity

5 Why is a µ special? µ R µ L CP- and Flavour-conserving, chirality-flipping, loop-induced b sγ compare: EDMs, B τν µ eγ EWPO

6 Why is a µ special? µ R µ L CP- and Flavour-conserving, chirality-flipping, loop-induced b sγ compare: EDMs, B τν µ eγ EWPO Note relation to m µ µ R µ L

7 Very different contributions to a µ generally: C = δm ( µ(n.p.) mµ ) 2, δa µ (N.P.) = O(C) m µ M classify new physics: C very model-dependent Very useful constraints on new physics

8 Very different contributions to a µ generally: C = δm ( µ(n.p.) mµ ) 2, δa µ (N.P.) = O(C) m µ M classify new physics: C very model-dependent Very useful constraints on new physics O(1) O( α 4π...) O( α 4π ) Z, W, UED, Littlest Higgs (LHT)... generic analysis talk S. Westhoff

9 Very different contributions to a µ generally: C = δm ( µ(n.p.) mµ ) 2, δa µ (N.P.) = O(C) m µ M classify new physics: C very model-dependent Very useful constraints on new physics O(1) supersymmetry (tan β), unparticles [Cheung, Keung, Yuan 07] O( α 4π...) extra dim. (ADD/RS) (n c)... [Davioudasl, Hewett, Rizzo 00] [Graesser, 00][Park et al 01][Kim et al 01] O( α 4π ) Z, W, UED, Littlest Higgs (LHT)... generic analysis talk S. Westhoff

10 Very different contributions to a µ generally: C = δm ( µ(n.p.) mµ ) 2, δa µ (N.P.) = O(C) m µ M classify new physics: C very model-dependent Very useful constraints on new physics O(1) radiative muon mass generation... [Czarnecki,Marciano 01] [Crivellin, Girrbach, Nierste 11][Dobrescu, Fox 10] supersymmetry (tan β), unparticles [Cheung, Keung, Yuan 07] O( α 4π...) extra dim. (ADD/RS) (n c)... [Davioudasl, Hewett, Rizzo 00] [Graesser, 00][Park et al 01][Kim et al 01] O( α 4π ) Z, W, UED, Littlest Higgs (LHT)... generic analysis talk S. Westhoff

11 Very different contributions to a µ generally: C = δm ( µ(n.p.) mµ ) 2, δa µ (N.P.) = O(C) m µ M classify new physics: C very model-dependent Very useful constraints on new physics O(1) radiative muon mass generation... [Czarnecki,Marciano 01] [Crivellin, Girrbach, Nierste 11][Dobrescu, Fox 10] supersymmetry (tan β), unparticles [Cheung, Keung, Yuan 07] O( α 4π...) extra dim. (ADD/RS) (n c)... [Davioudasl, Hewett, Rizzo 00] [Graesser, 00][Park et al 01][Kim et al 01] O( α 4π ) Z, W, UED, Littlest Higgs (LHT)... generic analysis talk S. Westhoff α 4π dark photon...

12 Complementarity Checking models with large a µ contributions electroweak scale models generic collider signals [Freitas,Lykken,Westhoff 14] SUSY specific LHC signals depending on scenario [Endo,Hamaguchi,Iwamoto,Yoshinaga 13] correlation to µ eγ,... dark photons low-energy signals Different types of new physics lead to very different δa µ (N.P.) very useful, complementary constraints on N.P only possible if M NP < 2TeV (for C 1)

13 Outline 1 Impact on New Physics in general Complementary Model dependent 2 Dark photon 3 SUSY Can explain the deviation tension with LHC data? details, new results Complementarity

14 What if the LHC does not find new physics? Dark sector still possible and appealing: L =... ǫ 2 Fµν d F µν A µ diag. L int =...(A µ +ǫa µ )Jµ e.m. Aµ d two parameters: coupling ǫ, mass m A is generic if there is new U(1) gauge boson (GUT, strings,...) window to possibly many new, SM-neutral particles Motivation: dark matter, (g 2) µ (assume specific coupling/mass range)

15 Dark photon and a µ A µ R µ L = ǫ 2 α ( ) 4π F mµ m A explain a µ without messing up a e : M A 1MeV 3 10 κ Excluded by electron g-2 vs α Excluded by muon g muon g-2 <2σ 6 10 [Pospelov 08] 10 MeV 100 MeV 500 MeV m V [Snowmass rept. 13] constrained by (g 2) e, Υ,K,φ,π meson decays,...

16 More on bounds on dark photons beam dump: dark bremsstrahlung (works for specific coupling range) electron fixed target (APEX,A1) Babar, KLOE, WASA: meson decays often assumed: A e + e dominant if not: K πa, A invisible and e + e γ+invisible lead to bounds [Davoudiasl,Lee,Marciano 14][Izaguirre et al 13] generalization: also mass mixing dark Z with more general couplings, also strongly constrained

17 Outline 1 Impact on New Physics in general Complementary Model dependent 2 Dark photon 3 SUSY Can explain the deviation tension with LHC data? details, new results Complementarity

18 SUSY and the MSSM ( 100GeV aµ SUSY tanβ sign(µ) M SUSY SUSY could be the origin of the observed (28±8) deviation! ) 2

19 SUSY and the MSSM ( 100GeV aµ SUSY tanβ sign(µ) M SUSY SUSY could be the origin of the observed (28±8) deviation! But has the LHC ruled out SUSY? ) 2

20 SUSY and the MSSM ( 100GeV aµ SUSY tanβ sign(µ) M SUSY SUSY could be the origin of the observed (28±8) deviation! But has the LHC ruled out SUSY? No! ) 2

21 SUSY and the MSSM ( 100GeV aµ SUSY tanβ sign(µ) M SUSY SUSY could be the origin of the observed (28±8) deviation! But has the LHC ruled out SUSY? No! Motivation: natural Higgs and EWSB, dark matter, GUT ) 2 free parameters: p masses and mixings, µ and tan β

22 LHC-data! The tension is increasing... LHC: a µ m q, g > 1TeV m µ,χ < 700GeV m h = 126 GeV m t > 1TeV finetuning m t,µ small

23 LHC-data! The tension is increasing... LHC: a µ m q, g > 1TeV m µ,χ < 700GeV m h = 126 GeV m t > 1TeV finetuning m t,µ small Distinguish SUSY from concrete models/scenarios Constrained MSSM links m q m µ m h cannot explain a µ Tension motivates non-traditional models: [Endo, Hamaguchi, Ibe, Yanagida, D.P. Roy, et al] sleptons squarks [ , ] 2nd gen 3rd gen [ ] new extra matter or U(1) (e.g. M 2 µ) [ , ]

24 LHC-data! The tension is increasing... LHC: a µ m q, g > 1TeV m µ,χ < 700GeV m h = 126 GeV m t > 1TeV finetuning m t,µ small Distinguish SUSY from concrete models/scenarios Constrained MSSM links m q m µ m h cannot explain a µ Tension motivates non-traditional models: [Endo, Hamaguchi, Ibe, Yanagida, D.P. Roy, et al] sleptons squarks [ , ] 2nd gen 3rd gen [ ] new extra matter or U(1) (e.g. M 2 µ) [ , ] Note: SUSY does not require φ CPV, δ LFV 0 a µ decoupled from LFV, EDMs

25 LHC-data! The tension is increasing... LHC: a µ m q, g > 1TeV m µ,χ < 700GeV m h = 126 GeV m t > 1TeV finetuning m t,µ small Distinguish SUSY from concrete models/scenarios Constrained MSSM links m q m µ m h cannot explain a µ Tension motivates non-traditional models: [Endo, Hamaguchi, Ibe, Yanagida, D.P. Roy, et al] sleptons squarks [ , ] 2nd gen 3rd gen [ ] new extra matter or U(1) (e.g. M 2 µ) [ , ] split/hierarchical spectra

26 It is worthwhile to look at the details

27 g 2 in the MSSM: chirality flips, λ µ, and H u tanβ = Hu H d, µ = H u H d transition H + d H + u W + W + some terms λ µ H u µ = m µ tanβ µ a SUSY µ tanβsign(µ) µ R ν µ µ L m 2 µ M 2 SUSY potential enhancement tanβ = (and sign(µ))

28 Physics of subleading contributions (examples) H + u W+ 1-loop bino B B 1-loop µ R H u B H + d W + H d B µ R ν µl µ L standard W H µ L µ L µ L µ R µ R µ for µ B µ L µ R µ L µ R µ R B H µ R other sign! [Fargnoli,Gnendiger,Passehr,DS,Stöckinger-Kim 13] note: at least 3 light (<TeV) masses

29 Physics of subleading contributions (examples) H + u W+ 1-loop bino B B 1-loop µ R H u B H + d W + H d B µ R ν µl µ L standard W H µ L µ L µ L µ R µ R µ for µ B µ L µ R µ L µ R µ R B H µ R other sign! small/large µ [Fargnoli,Gnendiger,Passehr,DS,Stöckinger-Kim 13] small/large M µl

30 Physics of subleading contributions (examples) H + u W+ 1-loop bino B B 1-loop µ R H u B H + d W + H d B µ R ν µl µ L standard W H µ L µ L µ L µ R µ R µ for µ B µ L µ R µ L µ R µ R B H µ R other sign! [Fargnoli,Gnendiger,Passehr,DS,Stöckinger-Kim 13] non-decoupling two-loop corrections γ f,f f χ 0, j χ 0, i µ µ, νµ µ

31 Complementarity to LHC: a µ central for BSM analyses SPS4 DS12 aμ SUSY SPS1b SPS1a SPS3 SPS2 SPS7 SPS6 SPS8 SPS5 SPS9 E1 E4 NS1 DS7 DS8 DS DS3 DS SPS benchmark points [v.weitershausen,schäfer, Stöckinger-Kim,DS 10] DS6 LHC Inverse Problem (300fb 1 ) can t be distinguished at LHC [Sfitter: Adam, Kneur, Lafaye, Plehn, Rauch, Zerwas 10] a µ sharply distinguishes BSM models here SUSY helps measure parameters [Hertzog, Miller, de Rafael, Roberts, DS 07] [Miller, de Rafael, Roberts, DS 12]

32 Correlation with µ eγ [talks by Gouvea, Lim] same structure additional mixing δ LL = m 2 L / m 2 L11 m 2 L22 12 H u W H d W µ R ν µ ν e e L study correlation for fixed δ LL aµ measured upper bound BR(µ eγ) < (MEG) e.g. can predict possible range of δll given aµ SUSY [Chacko,Kribs 01;Isidori,Mescia,Paradisi,Temes 07]

33 Correlation with µ eγ study correlation for fixed δ LL = However: strong correlation of individual diagrams does not imply strong correlation of the sum! Strong correlations for strong parameter constraints or domination of certain diagrams [Kersten,Park,DS,Velasco-Sevilla 14] black: from [Isidori et al]; other regions have looser constraints parameter regions where single diagrams dominate

34 Alternative: radiative muon mass in SUSY m tree µ = λ µ v d 1 λ µ = 0 generate m µ via A µ µ L µ R H u [Borzumati et al 99][Crivellin et al 11] 2 v d 0, tanβ generate m µ via coupling to v u [Dobrescu, Fox 10][Altmannshofer, Straub 10]

35 Radiative muon mass: MSSM for tanβ [Bach,Park,DS,Stöckinger-Kim, soon] standard case (equal masses, 1-loop) ( 100GeV aµ SUSY tanβ sign(µ) M SUSY ) 2

36 Radiative muon mass: MSSM for tanβ [Bach,Park,DS,Stöckinger-Kim, soon] H + u W+ actually, including higher order effects [Marchetti,Mertens,Nierste,DS 08] λ µ H + d W + µ R ν µ µ L m µ v d +v u(1-loop) = λ tree µ (1+ µtanβ) a SUSY µ tanβ sign(µ) tanβ sign(µ) ( 100GeV M SUSY ) 2

37 Radiative muon mass: MSSM for tanβ [Bach,Park,DS,Stöckinger-Kim, soon] limit tanβ ( ) 1000GeV 2 aµ SUSY M SUSY tanβ and sign(µ) drop out, large contributions for M SUSY TeV!

38 Radiative muon mass: MSSM for tanβ [Bach,Park,DS,Stöckinger-Kim, soon] limit tanβ standard case: sign wrong! ( ) 1000GeV 2 aµ SUSY M SUSY

39 Radiative muon mass: MSSM for tanβ [Bach,Park,DS,Stöckinger-Kim, soon] limit tanβ ( ) 1000GeV 2 aµ SUSY M SUSY sign positive e.g. if µ M SUSY (then B µ L µ R dominates)

40 What is it good for? Big questions EWSB, Higgs, mass generation? hierarchy M Pl /M W? Naturalness? Unification of the Coupling Constants in the SM and the minimal MSSM 1/α i /α i /α 1 MSSM /α dark matter? /α log Q Grand Unification? log Q...point to the TeV scale...and to new physics

41 What is it good for? Big questions EWSB, Higgs, mass generation? hierarchy M Pl /M W? Naturalness? Unification of the Coupling Constants in the SM and the minimal MSSM 1/α i /α i /α 1 MSSM /α dark matter? /α log Q Grand Unification? log Q SUSY, extra dimensions, little Higgs, technicolor,...

42 Why new physics? Big questions also motivate new physics at other scales Unification of the Coupling Constants in the SM and the minimal MSSM 1/α i /α i /α 1 MSSM /α dark matter? /α log Q Grand Unification? log Q Why three generations? Origin of flavor? m ν? Baryon asymmetry of the universe? Strong CP problem? dark forces, new CP/flavor violation, seesaw mechanism, axions,...

43 Conclusions Many appealing BSM scenarios a BSM µ model-dependent, typically O(±1...50) complementary models with large aµ BSM for M BSM < 1 GeV (dark photon) 100 GeV [talk Westhoff] 500 GeV (SUSY) > 1 TeV (rad. m µ ) already constrained by data details important New experiments very promising!!

44 Status of SUSY prediction 1-Loop 2-Loop (SUSY 1L) 2-Loop (SM 1L) tanβ e.g. log M SUSY m µ e.g. tanβµm t χ 0,± f t χ 0,± f H γ µ µ µ, ν [Fayet 80],... [Kosower et al 83],[Yuan et al 84],... [Lopez et al 94],[Moroi 96] µ µ µ, ν [Degrassi,Giudice 98] [Marchetti, Mertens, Nierste, DS 08] [Schäfer, Stöckinger-Kim, v. Weitershausen, DS 10] µ µ,ν µ µ [Chen,Geng 01][Arhib,Baek 02] [Heinemeyer,DS,Weiglein 03] [Heinemeyer,DS,Weiglein 04] complete photonic complete (tanβ) 2 aim: full calculation (65000 diagrams)

45 The new contributions with f f loops γ f,f f χ 0, j χ 0, i µ µ µ, ν µ Motivation: Split spectra remaining class with dependence on squarks maximum complexity: 5 heavy + 2 light scales

46 Result contains large logs, ρ χ i µ m, ν µ 1 µ µ a 1L µ ρ γ f,f 2 f χ 0, j χ 0, i µ µ, νµ µ a 1L µ log(m f )

47 Result contains large logs, ρ χ i µ m, ν µ 1 µ µ a 1L µ ρ γ f,f 2 f χ 0, j χ 0, i µ µ, νµ µ a 1L µ log(m f ) Old γ t 3 H t µ µ µ Z a 1L µ 1 m 2 f

48 Results for f f-loops: Large contributions from heavy squarks [Fargnoli, Gnendiger, Passehr, DS, Stöckinger-Kim 13] 0.15 BM4 r non-decoupling can be largest 2L contribution O(10%...30%) M GeV M U3, D3, Q3, E3, L3 M U, D, Q M Q3 ; M U3 1 TeV tan Β 2 photonic 2 L a µ = 160, M 1 = 140, m µr = 200, M 2 = m µl = 2000 GeV, tanβ = 50

49 Results for f f-loops: Large contributions from heavy squarks [Fargnoli, Gnendiger, Passehr, DS, Stöckinger-Kim 13] r BM M GeV non-decoupling can be largest 2L contribution O(10%...30%) M U3, D3, Q3, E3, L3 M U, D, Q M Q3 ; M U3 1 TeV tan Β 2 photonic 2 L a µ = 350, M 2 = 2M 1 = 300, m µr,l = 400 GeV, tanβ = 40

50 EWSB Models Large a µ possible? Randall Sundrum Littlest Higgs + T-Parity ( Bosonic SUSY ) 2-Higgs doublet model + 4th generation

51 EWSB Models Large a µ possible? Randall Sundrum Littlest Higgs + T-Parity ( Bosonic SUSY ) 2-Higgs doublet model + 4th generation Randall Sundrum KK-gravitons large [Kim, Kim, Song 01] However, challenged by electroweak precision data [Hewett et al 00] and γγ γγ unitarity [Kim,Kim,Song 01] non-graviton contributions small [Beneke, Dey, Rohrwild 12]

52 EWSB Models Large a µ possible? Randall Sundrum Littlest Higgs + T-Parity ( Bosonic SUSY ) 2-Higgs doublet model + 4th generation Littlest Higgs + T-Parity [Cheng, Low 03] [Hubisz, Meade, Noble, Perelstein 06] Tiny a µ from Z H, W H contributions [Blanke et al 07]

53 EWSB Models 5e-09 4e-09 Large a µ possible? Randall Sundrum a µ 3e-09 2e-09 M H + = 500 GeV m ν =100 GeV (black) 1e-09 =200 GeV (red) =400 GeV (blue) δ Σ2.δ U2 Littlest Higgs + T-Parity ( Bosonic SUSY ) 2-Higgs doublet model + 4th generation 2-Higgs doublet model + 4th generation [Bar-Shalom, Nandi, Soni 11] Large contributions from ν H ± possible in agreement with LFV, FCNC constraints

54 Other types of new physics What if the LHC does not find new physics? Hide new particles at colliders large a µ possible Dark force? [Pospelov, Ritz...] very light, weakly interacting C 10 8, M < 1GeV 3 10 κ Excluded by electron g-2 vs α Excluded by muon g-2 Light Z from gauged L µ L τ [Ma, Roy, Roy 02][Heeck, Rodejohann 11] flavour-dependent couplings, hidden at LEP C C SM,weak, M Z M Z [Pospelov 08] muon g-2 <2σ 10 MeV 100 MeV 500 MeV m V