Precision calculations for SUSY searches at hadron colliders

Transcription

1 Universitat de Barcelona, May 21th 2010 Precision calculations for SUSY searches at hadron colliders Michael Krämer (RWTH Aachen & IFAE Barcelona) 1 / 36

2 Physics beyond the Standard Model at the LHC Many new physics models are addressing two problems: the hierarchy/naturalness problem the origin of dark matter 2 / 36

3 Physics beyond the Standard Model at the LHC Many new physics models are addressing two problems: the hierarchy/naturalness problem the origin of dark matter The new physics needs to stabilize the Higgs mass M Higgs < 1 TeV decouple from electroweak precision tests ( discrete R/KK/T-parity) discrete symmetry new stable particles dark matter candidates 2 / 36

4 Physics beyond the Standard Model at the LHC Many new physics models are addressing two problems: the hierarchy/naturalness problem the origin of dark matter The new physics needs to stabilize the Higgs mass M Higgs < 1 TeV decouple from electroweak precision tests ( discrete R/KK/T-parity) discrete symmetry new stable particles dark matter candidates Popular new physics models that address the hierarchy problem Supersymmetry Extra dimensions Little Higgs models EWSB from strong dynamics 2 / 36

5 Physics beyond the Standard Model at the LHC Many new physics models are addressing two problems: the hierarchy/naturalness problem the origin of dark matter The new physics needs to stabilize the Higgs mass M Higgs < 1 TeV decouple from electroweak precision tests ( discrete R/KK/T-parity) discrete symmetry new stable particles dark matter candidates Popular new physics models that address the hierarchy problem Supersymmetry Extra dimensions Little Higgs models EWSB from strong dynamics spectrum of new particles at the TeV-scale with weakly interacting & stable particle ( discrete parity) 2 / 36

6 Physics beyond the Standard Model at the LHC Many new physics models are addressing two problems: the hierarchy/naturalness problem the origin of dark matter generic BSM signature at the LHC: cascade decays with E T,miss 3 / 36

7 New physics searches at the LHC no excess over SM expectation exclude models / set limits on model parameters excess in inclusive jets + E T,miss signal (early LHC phase) discriminate BSM models exploring BSM models (later LHC phase) directly determine quantum numbers, e.g. spin indirect searches virtual effects in SM processes and LFV decays 4 / 36

8 New physics searches at the LHC no excess over SM expectation exclude models / set limits on model parameters excess in inclusive jets + E T,miss signal (early LHC phase) discriminate BSM models exploring BSM models (later LHC phase) directly determine quantum numbers, e.g. spin indirect searches virtual effects in SM processes and LFV decays 5 / 36

9 New physics searches at the LHC no excess over SM expectation exclude MSSM parameter space / set limits on SUSY masses excess in inclusive jets + E T,miss signal (early LHC phase) discriminate BSM models exploring BSM models (later LHC phase) directly determine quantum numbers, e.g. spin indirect searches virtual effects in SM processes and LFV decays 6 / 36

10 SUSY searches: current mass limits CDF Run II Preliminary -1 L=2.0 fb 600 Theoretical uncertainties included observed limit 95% C.L. in the calculation of the limit expected limit mass limits (roughly) (GeV/c M~ q ) UA1 UA2 FNAL Run I LEP A 0 =0, tanβ=5, µ<0 M q ~ = M g ~ no msugra solution M g M q M gluino M t 1 M χ 0 1 M χ ± 1 M sleptons > 280 GeV > 400 GeV > 100 GeV > 50 GeV > 100 GeV > 100 GeV M 2 (GeV/c ) g ~ 7 / 36

11 SUSY searches: current mass limits CDF Run II Preliminary -1 L=2.0 fb 600 Theoretical uncertainties included observed limit 95% C.L. in the calculation of the limit expected limit mass limits (roughly) (GeV/c M~ q ) UA1 UA2 FNAL Run I LEP A 0 =0, tanβ=5, µ<0 M q ~ = M g ~ no msugra solution M g M q M gluino M t 1 M χ 0 1 M χ ± 1 M sleptons > 280 GeV > 400 GeV > 100 GeV > 50 GeV > 100 GeV > 100 GeV M 2 (GeV/c ) g ~ model dependence: M χ GeV possible (Dreiner, Grab, Koschade, MK, Langenfeld, O Leary PRD 09) 7 / 36

12 SUSY searches: current mass limits CDF Run II Preliminary -1 L=2.0 fb 600 Theoretical uncertainties included observed limit 95% C.L. in the calculation of the limit expected limit mass limits (roughly) (GeV/c M~ q ) UA1 UA2 FNAL Run I LEP A 0 =0, tanβ=5, µ<0 M q ~ = M g ~ no msugra solution M g M q M gluino M t 1 M χ 0 1 M χ ± 1 M sleptons > 280 GeV > 400 GeV > 100 GeV > 50 GeV > 100 GeV > 100 GeV M 2 (GeV/c ) g ~ squark & gluino limits based on NLO SUSY-QCD predictions (Beenakker, Höpker, MK, Plehn, Spira, Zerwas 96-??) 8 / 36

13 MSSM particle production at hadron colliders NLO corrections for MSSM particle production at hadron colliders public code Prospino (Beenakker, Höpker, MK, Plehn, Spira, Zerwas) determination of (mass) limits & tests of BSM models 9 / 36

14 MSSM particle production at hadron colliders determination of mass limits CDF Run II Preliminary -1 L=2.0 fb NLO Cross Section [pb] in the calculation of the limit 10 NLO: PROSPINO CTEQ6.1M Theoretical uncertainties not included syst. uncert. (PDF Ren.) observed limit 95% C.L. expected limit 95% C.L M g ~ = M q ~ M g ~ [GeV/c ] 10 / 36

15 MSSM particle production at hadron colliders determination of mass limits 11 / 36

16 MSSM particle production at hadron colliders NLO corrections for MSSM particle production at hadron colliders public code Prospino (Beenakker, Höpker, MK, Plehn, Spira, Zerwas) large corrections of O(100%) for m > 500 GeV 12 / 36

17 Threshold summation for SUSY cross sections Cross section near threshold β = p 1 4m 2 /s 1: σ NLO [gg q q + X ] α2 s (µ 2 ) m 2 7π 384 β j 1 + 4πα s(µ 2 11 ) 336β + 3 2π 2 ln2 (8β 2 ) π 2 ln(8β2 ) 2 «ff«µ 2 3π 2 ln(8β2 ) ln m 2 13 / 36

18 Threshold summation for SUSY cross sections Cross section near threshold β = p 1 4m 2 /s 1: dσ = dσ LO (1 + α s log 2 β 2 + log β αs 2 log 4 β 2 + log 3 β 2 + log 2 β 2 + log β α n s log 2n β 2 + log 2n 1 β / 36

19 Threshold summation for SUSY cross sections Cross section near threshold β = p 1 4m 2 /s 1: dσ = dσ LO (1 + α s log 2 β 2 + log β αs 2 log 4 β 2 + log 3 β 2 + log 2 β 2 + log β α n s log 2n β 2 + log 2n 1 β requires all order summation of large logarithmic corrections: (Beenakker, Brensing, MK, Kulesza, Laenen, Niessen, JHEP 09) 0 dσ res B dσ LO β 2 g 1(α s log β 2 ) + g 2(α s log β 2 C ) +... A +... {z } {z } LL NLL 1 14 / 36

20 Threshold summation for SUSY cross sections K NLL σ(resummed + NLO resummed NLO)/σ(NLO) K NLL 1 ( p p q g + X ) S = 1.96 TeV r = m g m q µ = m K NLL 1 ( pp q g + X ) S = 14 TeV r = m g m q µ = m m[gev] 500 r=2.0 r=1.0 r=0.8 r= m[gev] r=2.0 r=1.0 r=0.8 r= NLL enhancement near central scales between 5% and 40% 15 / 36

21 Threshold summation for SUSY cross sections σ matched = σ resummed + σ NLO σ resummed NLO σ(µ) σ(µ 0) ( p p q q + g g + q q + q g + X ) S = 1.96 TeV NLO, µ = 1 2 m NLO + NLL, µ = 1 2 m NLO + NLL, µ = 2m NLO, µ = 2m 0.8 µ 0 = m m[gev] σ(µ) σ(µ 0) ( pp q q + g g + q q + q g + X ) S = 14 TeV µ 0 = m NLO, µ = 1 2 m NLO + NLL, µ = 1 2 m NLO + NLL, µ = 2m NLO, µ = 2m m[gev] reduction of scale dependence σ < 20 (10)% at the TeV (LHC) 16 / 36

22 Threshold summation for SUSY cross sections σ matched = σ resummed + σ NLO σ resummed NLO σ(µ) σ(µ 0) ( p p q q + g g + q q + q g + X ) S = 1.96 TeV NLO, µ = 1 2 m NLO + NLL, µ = 1 2 m NLO + NLL, µ = 2m NLO, µ = 2m 0.8 µ 0 = m m[gev] σ(µ) σ(µ 0) ( pp q q + g g + q q + q g + X ) S = 14 TeV µ 0 = m NLO, µ = 1 2 m NLO + NLL, µ = 1 2 m NLO + NLL, µ = 2m NLO, µ = 2m m[gev] currently most accurate prediction will sharpen Tevatron bounds 17 / 36

23 Progress in SUSY precision calculations at the LHC Sparticle production cross sections NLO QCD Prospino: Beenakker, Höpker, MK, Plehn, Spira, Zerwas (cf. Baer, Hall, Reno; Berger, Klasen, Tait) threshold summation for M q, M g > 1 TeV (Bozzi, Debove, Fuks, Klasen; Kulesza, Motyka; Langenfeld, Moch; Beenakker, Brensing, MK, Kulesza, Laenen, Niessen) electroweak corrections (Hollik, Kollar, Mirabella, Trenkel; Bornhauser, Drees, Dreiner, Kim; Beccaria, Macorini, Panizzi, Renard, Verzegnassi) beyond MSSM: NLO QCD for RPV SUSY (Choudhury, Majhi, Ravindran; Yang, Li, Liu, Li; Dreiner, Grab, MK, Trenkel) Sparticle decays total rates Sdecay: (Mühlleitner, Djouadi, Mambrini) + many others... only few results for shapes (Drees, Hollik, Xu; Horsky, MK, Mück, Zerwas) 18 / 36

24 New physics searches at the LHC no excess over SM expectation exclude models / set limits on model parameters excess in inclusive jets + E T,miss signal (early LHC phase) discriminate BSM models exploring BSM models (later LHC phase) directly determine quantum numbers, e.g. spin indirect searches virtual effects in SM processes and LFV decays 19 / 36

25 BSM searches at the LHC: the early phase Mass measurements from cascade decays, e.g. 20 / 36

26 BSM searches at the LHC: the early phase Mass measurements from cascade decays, e.g. kinematic endpoints sensitive to masses: (m 2 ll) max = (m 2 χ 0 2 m2 l R )(m 2 l R m 2 χ 0 1 )/m2 l R (m 2 qll) max = (m 2 q L m 2 χ 0 2 )(m2 χ 0 2 m2 χ 0 1 )/m2 χ 0 2 (m 2 ql,min) max = (m 2 q L m 2 χ 0 2 )(m2 χ 0 2 m2 l R )/m 2 χ 0 2 (m 2 ql,max) max = (m 2 q L m 2 χ 0 2 )(m2 lr m 2 χ 0 1 )/m2 lr 20 / 36

27 BSM searches at the LHC: the early phase msugra fit using Fittino (Bechtle, Desch, Wienemann) low scale masses RG evolution high scale parameters GeV SPS1a m Ql (µ 2 2 1/2 +m Hd ) M 3 M 2 M 1 m Er (µ 2 2 +m Hu ) 1/2 SOFTSUSY log 10 (µ/gev) 21 / 36

28 BSM searches at the LHC: the early phase msugra fit using Fittino (Bechtle, Desch, Wienemann) 14 TeV & 10 fb 1 : kinematic edges + additional observables 22 / 36

29 BSM searches at the LHC: the early phase msugra fit using Fittino (Bechtle, Desch, Wienemann) 14 TeV & 10 fb 1 : kinematic edges + additional observables parameter nominal fit error m 0 [GeV] ±1.5 m 1/2 [GeV] ±1.2 tan β ±1 A 0 [GeV] ±50 22 / 36

30 BSM searches at the LHC: the early phase msugra fit using Fittino (Bechtle, Desch, Wienemann) 14 TeV & 10 fb 1 : kinematic edges + additional observables parameter nominal fit error (GeV) M m 0 [GeV] ±1.5 m 1/2 [GeV] ±1.2 tan β ±1 A 0 [GeV] ± M 1/2 (GeV) accurate determination of model parameters 22 / 36

31 BSM searches at the LHC: the early phase How well can we do at 7 TeV and 1 fb 1? 23 / 36

32 BSM searches at the LHC: the early phase How well can we do at 7 TeV and 1 fb 1? (GeV) M (GeV) M 1/2 2 0 kinematic edges only no stable fit! need to add additional observables 23 / 36

33 BSM searches at the LHC: the early phase Add cross sections: contain crucial information on masses and quantum numbers of new particles m gluino [GeV] m squark [GeV] σ [pb] / 36

34 BSM searches at the LHC: the early phase How well can we do at 7 TeV and 1 fb 1? (GeV) M (GeV) M 1/2 2 0 kinematic edges only no stable fit! need to add additional observables 25 / 36

35 BSM searches at the LHC: the early phase How well can we do at 7 TeV and 1 fb 1? (GeV) (GeV) M M (GeV) M 1/ (GeV) M 1/2 2 0 kinematic edges only no stable fit! need to add additional observables kinematic edges cross sections m 0 = 99 ± 9 GeV m 1/2 = 250 ± 7 GeV tan β = 11 ± 6 25 / 36

36 BSM searches at the LHC: the early phase How well can we do at 7 TeV and 1 fb 1? (GeV) (GeV) M M (GeV) M 1/ (GeV) M 1/2 2 0 kinematic edges only no stable fit! need to add additional observables kinematic edges cross sections m 0 = 99 ± 9 GeV m 1/2 = 250 ± 7 GeV tan β = 11 ± 6 inclusion of cross sections is crucial to determine BSM parameters Dreiner, MK, Lindert, O Leary, JHEP / 36

37 BSM searches at the LHC: the early phase Why have cross sections so far not been included in LHC BSM fits? calculation time consuming (cf. Lester et al.) large uncertainty at LO 26 / 36

38 BSM searches at the LHC: the early phase Why have cross sections so far not been included in LHC BSM fits? calculation time consuming (cf. Lester et al.) large uncertainty at LO Our solution: combine parametrizations and analytical calculations quick & accurate estimate of σ BR acceptance 26 / 36

39 BSM searches at the LHC: the early phase Why have cross sections so far not been included in LHC BSM fits? calculation time consuming (cf. Lester et al.) large uncertainty at LO Our solution: combine parametrizations and analytical calculations quick & accurate estimate of σ BR acceptance Exploring BSM physics at the LHC: current and future work explore regions with 3-body decays, e.g. DM focus point regions include shapes of distributions consider non-minimal models, e.g. mirage mediation (Choi, Falkowski, Nilles, Olechowski, Pokorski,...) beyond SUSY: UED, little Higgs models,... model-independent characterization of first new physics signals? 26 / 36

40 New physics searches at the LHC no excess over SM expectation exclude models / set limits on model parameters excess in inclusive jets + E T,miss signal (early LHC phase) discriminate BSM models exploring BSM models (later LHC phase) directly determine quantum numbers, e.g. spin indirect searches virtual effects in SM processes and LFV decays 27 / 36

41 BSM parameter determination: spin Use shape of distributions to determine new particle spin consider charge asymmetry (Barr) A = (dσ/dm ql + dσ/dm ql ) (dσ/dm ql + + dσ/dm ql ) 28 / 36

42 BSM parameter determination: spin Use shape of distributions to determine new particle spin (Horsky, MK, Mück, Zerwas, PRD 08) consider charge asymmetry (Barr) A = (dσ/dm ql + dσ/dm ql ) (dσ/dm ql + + dσ/dm ql ) 28 / 36

43 BSM parameter determination: spin Use shape of distributions to determine new particle spin consider charge asymmetry (Barr) A = (dσ/dm ql + dσ/dm ql ) (dσ/dm ql + + dσ/dm ql ) 29 / 36

44 BSM parameter determination: spin Use shape of distributions to determine new particle spin consider charge asymmetry (Barr) A = (dσ/dm ql + dσ/dm ql ) (dσ/dm ql + + dσ/dm ql ) Alternative: consider jet events shapes (MK, Popenda, Spira, Zerwas, PRD 09) 30 / 36

45 BSM parameter determination: spin Use shape of distributions to determine new particle spin consider charge asymmetry (Barr) A = (dσ/dm ql + dσ/dm ql ) (dσ/dm ql + + dσ/dm ql ) Alternative: consider jet events shapes (MK, Popenda, Spira, Zerwas, PRD 09) spin effects are typically only around 10%, challenging for LHC 30 / 36

46 New physics searches at the LHC no excess over SM expectation exclude models / set limits on model parameters excess in inclusive jets + E T,miss signal (early LHC phase) discriminate BSM models exploring BSM models (later LHC phase) directly determine quantum numbers, e.g. spin indirect searches virtual effects in SM processes and LFV decays 31 / 36

47 Indirect searches at the LHC I: virtual effects E.g. MSSM corrections to single W -production (Brensing, Dittmaier, MK, Mück PRD 08) 32 / 36

48 Indirect searches at the LHC I: virtual effects E.g. MSSM corrections to single W -production (Brensing, Dittmaier, MK, Mück PRD 08) Numerical results: p T,l distribution pp ν l l + (+γ) at s = 14TeV p T,l /GeV SPS1a δ SUSY QCD/% SPS1a δ SUSY EW/% SPS2 δ SUSY QCD/% SPS2 δ SUSY EW/% / 36

49 Indirect searches at the LHC I: virtual effects E.g. MSSM corrections to single W -production (Brensing, Dittmaier, MK, Mück PRD 08) Numerical results: p T,l distribution pp ν l l + (+γ) at s = 14TeV p T,l /GeV SPS1a δ SUSY QCD/% SPS1a δ SUSY EW/% SPS2 δ SUSY QCD/% SPS2 δ SUSY EW/% virtual effects from MSSM corrections are generically small (cf. electroweak precision test) see also virtual SUSY effects in top production (Berge, Hollik, Mösle, Wackeroth) 32 / 36

50 Indirect searches at the LHC II: rare processes E.g. lepton-flavour violating decays τ µµ µ (Giffels, Kallarackal, MK, O Leary, Stahl PRD 08) 33 / 36

51 Indirect searches at the LHC II: rare processes E.g. lepton-flavour violating decays τ µµ µ (Giffels, Kallarackal, MK, O Leary, Stahl PRD 08) strongly suppressed in the SM potentially large in many BSM scenarios (SUSY, little Higgs, technicolour,... ) with O(100) events/100 fb 1 33 / 36

52 Indirect searches at the LHC II: rare processes E.g. lepton-flavour violating decays τ µµ µ (Giffels, Kallarackal, MK, O Leary, Stahl PRD 08) strongly suppressed in the SM potentially large in many BSM scenarios (SUSY, little Higgs, technicolour,... ) with O(100) events/100 fb 1 discrimate BSM models from differential decay distributions 33 / 36

53 What about backgrounds? backgrounds will be obtained from data 34 / 36

54 What about backgrounds? backgrounds will be obtained from data Dissertori 34 / 36

55 What about backgrounds? backgrounds will be obtained from data Dissertori need matching of higher-order calculations with parton showers 34 / 36

56 Thanks for your attention! and thanks to... my students, postdocs and collabarators Wim Beenakker, Silja Brensing, Stefan Dittmaier, Herbi Dreiner, Manuel Giffels, Roland Höpker, Roman Horsky, Jim Kallarackal, Anna Kulesza, Eric Laenen, Jonas Lindert, Alexander Mück, Irene Niessen, Ben O Leary, Tilman Plehn, Eva Popenda, Achim Stahl, Michael Spira, Peter Zerwas and my sponsors SFB/TR 9 Computational Particle Physics, Helmholtz Alliance Physics at the Terascale, BMBF-Theorie-Verbund, Marie Curie Research Training Network Heptools, Graduiertenkolleg Elementarteilchenphysik an der TeV-Skala 35 / 36

57 Backup slides 2 / 1

58 SUSY particle production at hadron colliders SUSY particles would be produced copiously at hadron colliders via QCD processes, eg σ tot Tevatron LHC g g SUSY signal LHC σ( q q + g g + g q) 100 pb (M q, g 500 GeV) σ (nb) σ bbar σ jet (E T jet > s/20) σ W σ Z σ jet (E T jet > 100 GeV) events/sec for L = cm -2 s σ ttbar σ jet (E T jet > s/4) σ Higgs (M H = 150 GeV) σ Higgs (M H = 500 GeV) s (TeV) page 9

59 SUSY particle production at hadron colliders SUSY particles would be produced copiously at hadron colliders via QCD processes, eg σ tot Tevatron LHC g g SUSY signal Tevatron σ( q q + g g + g q) 5 fb (M q, g 500 GeV) σ (nb) σ bbar σ jet (E T jet > s/20) σ W σ Z σ jet (E T jet > 100 GeV) σ ttbar σ jet (E T jet > s/4) events/sec for L = cm -2 s σ Higgs (M H = 150 GeV) σ Higgs (M H = 500 GeV) s (TeV) page 10

60 Example: top-squark searches Top-squark search in p p t 1 t 1 c χ 0 1 c χ 0 1 channel (CDF PRD 2007) (pb) 2 1 )) cχ CDF Run II Preliminary (295 pb ) Theory Cross Section (Prospino) NLO Uncertainty (scale+pdf) ~ t 1 ) (BR( ~ t 1 σ(pp ~ t 1 10 CDF Upper Limit, 95% CL Observed Expected M(χ 0 )=50 GeV/c ~ M( t 1 ) (GeV/c ) 105 GeV M t GeV page 12

61 Example: top-squark searches Top-squark search in p p t 1 t 1 c χ 0 1 c χ 0 1 channel (CDF PRD 2007) no exclusion based on LO cross sections page 13

62 Threshold summation for SUSY cross sections NLO cross section near threshold β = 1 4m 2 /s 1: σ NLO [q q t 1 t 1 + X] α2 s(µ 2 ) m 2 ( { π 54 β πα s (µ 2 ) π 2 ln(8β2 ) 2 3π 2 ln(8β2 ) ln 48β + 2 3π 2 ln2 (8β 2 ) ( ) }) µ 2 m 2 σ NLO [gg t 1 t 1 + X] α2 s (µ2 ) m 2 ( { 7π β 1 + 4πα s (µ 2 ) π 2 ln(8β2 ) 2 3π 2 ln(8β2 ) ln 336β + 3 2π 2 ln2 (8β 2 ) ( )}) µ 2 m 2 large universal corrections ln (1,2) (β) all order summation of large logarithmic corrections (Beenakker, Brensing, MK, Kulesza, Laenen, Niessen, arxiv: [hep-ph]) page 15

63 BSM parameter determination Cross section are sensitive to spin, for example stop vs top production: q + q q + q q g t 1 t t 1 g q t 1 t t 1 ˆσ LO [q q q q] = α2 sπ s c.f. top production: ˆσ LO [q q QQ] = α2 sπ s 4 27 β3 (β 2 = 1 4m 2 /s) 8 (s + 2m 2 ) 27 s 2 β σ top /σ stop 10 at the Tevatron page 25

64 BSM parameter determination Cross section are sensitive to spin, for example stop vs top production: (Kane, Petrov, Shao, Wang) 100 t s t s Cross Section pb D0 CDF tt mass GeV no production of scalar quarks (assuming same mass and couplings as top... ) page 26

65 BSM parameter determination What about shapes? (cf. Gjelsten, Miller, Osland, Raklev) M (ll) inv 0.1 +:tanβ=14.5 VS. -:tanβ=5 (MK, Lindert, O Leary) 0.08 OS-SF - OS-DF; + OS-SF - OS-DF; differences in shapes are small for SPS1a-type msugra scenarios page 27

66 BSM parameter determination: resolve ambiguities? SPS1a scenario (M 0 = 100 GeV, M 1/2 = 250 GeV) masses / GeV m χ 0 1 m lr m χ 0 2 m ql real mimic edges / GeV m max ll m max qll m max ql (high) m max ql (low) Shapes (e.g. m ql (low)): mql low GeV SPS1a and its mimic point cannot be distinguished by shapes page 28

67 BSM parameter determination: resolve ambiguities? Alternative scenario (M 0 = 200 GeV, M 1/2 = 350 GeV) masses / GeV m χ 0 1 m lr m χ 0 2 m ql real mimic edges / GeV m max ll m max qll m max ql (high) m max ql (low) Shapes (e.g. m ql (low)): mql low GeV looks more promising, but... page 29

68 BSM parameter determination: resolve ambiguities? Alternative scenario (M 0 = 200 GeV, M 1/2 = 350 GeV) Shapes (e.g. m ql (low)): masses / GeV m χ 0 1 m lr m χ 0 2 m ql real mimic edges / GeV m max ll m max qll m max ql (high) m max ql (low) smeared by SUSY backgrounds (combinatorics) page 30

69 A crucial test of the MSSM: the light Higgs One of the MSSM Higgs bosons will be seen at the LHC tanβ h 0 H A H ATLAS ATLAS fb maximal mixing h 0 H A 0 0 h H h H 0 h only LEP 2000 LEP excluded 2 0 h 0 H A H 0 h H m A (GeV) but it may look like the SM Higgs need precision calculations page 37

70 Higgs production in the MSSM Cross section predictions: light and heavy scalar h and H [Spira] Cross-section (pb) h H Hbb tan β = 30 Maximal mixing gg H (SM) Hqq gg H 10-2 Htt HZ HW m h/h (GeV) page 38

71 Higgs production in the MSSM: associated b bh production Associated Q Q-Higgs production P P g g Q φ Q is crucial as a Higgs discovery channel to measure the heavy-quark Higgs Yukawa couplings In the MSSM one has pp Q Q + h, H, A pp Q Q + H ± Relative importance depends on MSSM parameters tan β and M A, eg.: g MSSM bbh = sin α cos β gsm bbh tan β 1 tan β g SM bbh (M h M A M Z ) page 39

72 Associated Heavy Quark Higgs Production Comprehensive program to calculate NLO-QCD corrections to associated heavy-quark Higgs production in the MSSM (Dittmaier, MK, Spira,... ) p + p h/h/a/h ± + Q Q technically challenging; tools & techniques developed in pp t th (Beenakker, Dittmaier, MK, Plümper, Spira, Zerwas) repository of tools & techniques for generic 2 3 processes at the LHC calculations are set up as parton level Monte Carlo programs can predict cross sections & distributions with kinematic cuts page 40

73 Associated Heavy Quark Higgs Production Comprehensive program to calculate NLO-QCD corrections to associated heavy-quark Higgs production in the MSSM (Dittmaier, MK, Spira,... ) p + p h/h/a/h ± + Q Q recent result: pp tbh ± at NLO in SUSY-QCD (Dittmaier, MK, Spira, Walser) σ (pp t bh + X) [fb] s = 14 TeV µ 0 = (m b + m t + m H )/ m H = 214 GeV 1000 NLO LO µ/µ 0 page 41

74 Associated Heavy Quark Higgs Production Comprehensive program to calculate NLO-QCD corrections to associated heavy-quark Higgs production in the MSSM (Dittmaier, MK, Spira,... ) p + p h/h/a/h ± + Q Q pp tbh ± : comparison of 4- and 5-FS at NLO (Dittmaier, MK, Spira, Walser; Plehn) 1000 σ (pp th + X) [fb] s = 14 TeV µ = (m b + m t + m H )/ FS NLO QCD 4FS NLO QCD M H [GeV] page 42

75 Associated Heavy Quark Higgs Production Comprehensive program to calculate NLO-QCD corrections to associated heavy-quark Higgs production in the MSSM (Dittmaier, MK, Spira,... ) p + p h/h/a/h ± + Q Q Work in progess & future plans complete numerical analysis for pp Q Qh/H/A investigate difference between 4- and 5FS calculations (cf. ACOT scheme in DIS) (MK, Olness Soper) include EWK corrections (cf. EWK corrections to b b h/h/a) (Dittmaier, MK, Mück, Schlüter) parton level MC for b b h/h/a at NNLO (Harlander, MK) ( finite top mass corrections to pp H through gluon fusion) page 43

76 Precision calculations for the LHC Production of supersymmetry and large extra dimensions Indirect search for new physics Higgs signal and background calculations New tools for LHC physics Experiments measure multi-parton final states in restricted phase space region need flexible and realistic precision calculations precise including loops & many legs flexible allowing for exclusive cross sections & phase space cuts realistic matched with QCD parton showers and hadronisation page 46

77 NLO calculations with parton showers & hadronization Fixed-oder calculations have limitations they do not predict realistic final states experimentally theoretically at LO page 47

78 NLO calculations with parton showers & hadronization Fixed-oder calculations have limitations they do not predict realistic final states experimentally theoretically at NLO page 48

79 NLO calculations with parton showers & hadronization Fixed-oder calculations have limitations they break down for certain kinematic configurations [MK, Mrenna, Soper] e + e 3 jets: jet-mass distribution df 3 /dm [GeV -1 ] 0.1 ( s = M Z ; µ = s/6, k T algorithm, y cut = 0.05) NLO wrong jet structure for M M [GeV] page 49

80 NLO calculations with parton showers & hadronization Fixed-oder calculations have limitations add parton showers summation of multi-parton emission [MK, Mrenna, Soper] e + e 3 jets: jet-mass distribution f -1 3 df 3 /dm [GeV-1 ] ( s = M Z ; µ = s/6, k T algorithm, y cut = 0.05) NLO NLO+Pythia M [GeV] realistic jet structure and accurate (NLO) prediction for rate page 50

81 NLO calculations with parton showers & hadronization NLO PS matching formalism avoid double counting: parton showers include part of the short-distance physics already included in the NLO calculation various schemes have been proposed (Frixione, Webber; Nason, Oleari; Collins, Zu; Soper, MK, Nagy; Giele, Kosower, Skands; Bauer, Schwarz,... ), but currently only public code for e + e 3 jets (MK, Mrenna, Soper) and for various LHC processes in MC@NLO (Frixione, Webber et al.) and Powheg (Nason, Oleari et al.) Current & future work improved subtraction scheme with minimal number of subtraction terms (Chung, MK, Nagy, Robens, Soper) automated NLO multi-leg subtraction matching with improved parton shower including quantum interference and sub-leading colour page 51