Precision calculations for LHC physics

Transcription

1 Colloquium PSI, Mai 29 Precision calculations for LHC physics Michael Krämer (RWTH Aachen) Sponsored by: 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 page 1

2 Why precision calculations for LHC physics? We do not need theory input for LHC discoveries Events / 5 MeV for 1 5 pb CMS, 1 5 pb -1 Higgs signal m γγ (GeV) page 2

3 Why precision calculations for LHC physics? We do not need theory input for LHC discoveries Events / 5 MeV for 1 5 pb CMS, 1 5 pb -1 Higgs signal m γγ (GeV) but only if we see a resonance... page 2

4 Contents Why precision calculations for LHC physics? lessons from the past prospects: Higgs & BSM searches Theoretical tools for LHC phenomenology (N)NLO multi-leg calculations matching with parton showers & hadronization page 3

5 Contents Why precision calculations for LHC physics? lessons from the past prospects: Higgs & BSM searches Theoretical tools for LHC phenomenology talking about theoretical tools at PSI: carrying coals to Newcastle... page 4

6 Contents Why precision calculations for LHC physics? lessons from the past prospects: Higgs & BSM searches page 5

7 Why precision calculations for LHC physics? Tevatron jet cross section at large E T 1 (Data - Theory)/ Theory.5 CTEQ3M CDF (Preliminary) * 1.3 D (Preliminary) * E t (GeV) page 6

8 Why precision calculations for LHC physics? Tevatron jet cross section at large E T 1 (Data - Theory)/ Theory.5 CTEQ3M CDF (Preliminary) * 1.3 D (Preliminary) * E t (GeV) new physics? +? page 7

9 Why precision calculations for LHC physics? Tevatron jet cross section at large E T 1 (Data - Theory)/ Theory.5 CTEQ3M CDF (Preliminary) * 1.3 D (Preliminary) * E t (GeV) L BSM g2 M 2 ψγ µ ψ ψγ µ ψ data theory theory g 2 E2 T M 2 page 8

10 Why precision calculations for LHC physics? Tevatron jet cross section at large E T (nb/gev) dη σ / de T 2 d 1 2 CDF Run II Preliminary 1 Integrated L = 85 pb < η 1-1 Det <.7 JetClu Cone R = Run II Data CTEQ 6.1 Uncertainty +/- 5% Energy Scale Uncertainty Inclusive Jet E T (GeV) just QCD... (uncertainty in gluon pdf at large x) page 9

11 Why precision calculations for LHC physics? Tevatron bottom quark cross section [D, PLB 487 (2)] new physics? page 1

12 Why precision calculations for LHC physics? Tevatron bottom quark cross section [Berger et al., PRL 86 (21)] Sum QCD g ~ b min σ b (p T p T ) (nb) S = 1.8 TeV m~ g = 14 GeV D Data CDF Data m~ b = 3.5 GeV 1 m b = 4.75 GeV min p T (GeV) light gluino/sbottom production? page 11

13 Why precision calculations for LHC physics? Tevatron bottom quark cross section [Mangano, AIP Conf.Proc, 25] just QCD... (α s, low-x gluon pdf, b B fragmentation & exp. analyses) page 12

14 Why precision calculations for LHC physics? Signals of discovery include mass peaks anomalous shapes of kinematic distributions excess of events after kinematic selection page 13

15 Why precision calculations for LHC physics? Signals of discovery include mass peaks anomalous shapes of kinematic distributions e.g. jet production at large E T excess of events after kinematic selection e.g. bottom cross section page 13

16 Why precision calculations for LHC physics? Signals of discovery include mass peaks e.g. Higgs searches in H γγ/zz final states anomalous shapes of kinematic distributions e.g. SUSY searches in multijet + E T,miss final states excess of events after kinematic selection e.g. Higgs searches in H W W final states page 14

17 Why precision calculations for LHC physics? Signals of discovery include mass peaks e.g. Higgs searches in H γγ/zz final states anomalous shapes of kinematic distributions e.g. SUSY searches in multijet + E T,miss final states excess of events after kinematic selection e.g. Higgs searches in H W W final states 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 parton showers and hadronization page 14

18 Searches at the LHC: outline Examples from Higgs physics discovery from excess of events: pp H W W pp t th be aware of backgrounds... page 15

19 Searches at the LHC: outline Examples from Higgs physics discovery from excess of events: pp H W W pp t th be aware of backgrounds... Examples from beyond the standard model physics: BSM searches with multi-jet + E T,miss signatures no excess over SM expectations 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) determine masses & spins page 15

20 Higgs searches at the LHC: be aware of backgrounds pp H W W pp t th page 16

21 Higgs searches at the LHC: pp H W W l + νl ν g g H W W + ν l l + ν neutrinos in final state no invariant Higgs mass peak large background from QCD process q q W W Events / 5 GeV 3 2 exploit lepton rapidity distributions and angular correlations to suppress background 1 (Dittmar, Dreiner) m T (GeV) page 17

22 Higgs searches at the LHC: pp H W W l + νl ν LO background from q q scattering page 18

23 Higgs searches at the LHC: pp H W W l + νl ν LO background from q q scattering experimental selection cuts may enhance the importance of higher-order corrections for background processes: page 18

24 Higgs searches at the LHC: pp H W W l + νl ν LO background from q q scattering experimental selection cuts may enhance the importance of higher-order corrections for background processes: gg W W l ν l ν [Binoth, Ciccolini, Kauer, MK; Dührssen, Jakobs, van der Bij, Marquard] g d W l g d d ν u W + ν l formally NNLO but enhanced by Higgs search cuts page 18

25 Higgs searches at the LHC: pp H W W l + νl ν LO background from q q scattering experimental selection cuts may enhance the importance of higher-order corrections for background processes: gg W W l ν l ν [Binoth, Ciccolini, Kauer, MK; Dührssen, Jakobs, van der Bij, Marquard] g g d d d W l ν u W + ν l q q (NLO) gg corr. σ tot 1373 fb 54 fb 4% σ bkg 4.8 fb 1.39 fb 3% formally NNLO but enhanced by Higgs search cuts page 18

26 Higgs searches at the LHC: be aware of backgrounds pp H W W pp t th page 19

27 Higgs searches at the LHC: pp t th( b b) q W + q ' g t b b t,t H +... g t W - b b l ν small cross section: σ(t th)/σ(h + X) 1/1 only relevant for M H < 14 GeV distinctive final state: pp t( W + b) t( W b) H( b b) cross section g 2 tth unique way to measure top-higgs Yukawa coupling page 2

28 Higgs searches at the LHC: pp t th( b b) theoretical uncertainty of signal 2% at NLO [Beenakker, Dittmaier, MK, Plümper, Spira, Zerwas] σ(pp tt _ H + X) [fb] s = 14 TeV M H = 12 GeV µ = m t + M H /2 LO NLO µ/µ page 21

29 Higgs searches at the LHC: pp t th( b b) invariant mass spectrum [CMS (Benedetti et al.)] 2 # events per 2 GeV/c tth 115 ttnj ttbb ttz Higgs mass [GeV/c ] similar shapes for signal and background (t t + n jets, t tb b, t tz) counting experiment precise knowledge of event rates required page 22

30 Higgs searches at the LHC: pp t th( b b) need to know backgrounds much better than 1%! [CMS (Benedetti et al.)] try to determine reducible backgrounds from data need accurate theory to extrapolate into signal region page 23

31 Higgs searches at the LHC: pp t th( b b) pp t tb b + X at NLO [Bredenstein, Denner, Dittmaier, Pozzorini 9] σ [fb] 1 pp t tb b + X NLO LO 1 1 m t = GeV µ /2 < µ < 2µ m b b, cut [GeV] page 24

32 Searches at the LHC: outline Examples from Higgs physics discovery from excess of events: pp H W W pp t th be aware of backgrounds... Examples from beyond the standard model physics: BSM searches with multi-jets + E T,miss signatures no excess over SM expectations 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) determine masses & spins page 25

33 BSM searches at the LHC Many model for new physics are addressing two problems: the hierarchy/naturalness problem the origin of dark matter spectrum of new particles at the TeV-scale with weakly interacting & stable particle page 26

34 BSM searches at the LHC Many model for new physics are addressing two problems: the hierarchy/naturalness problem the origin of dark matter spectrum of new particles at the TeV-scale with weakly interacting & stable particle generic BSM signature at the LHC involves cascade decays with missing energy, eg. supersymmetry g ~ ~ g t q ~ ~ t 1 q ~ χ2 ~ l + q ~ χ 1 ~ χ 1 l - l + W t W + ν l + b q q b page 26

35 BSM searches at the LHC 1-7 LHC Point 5 simple discriminant for SUSY searches: effective mass M eff = E T,miss + 4 i=1 pjet T excess of events with large M eff initial discovery of SUSY dσ/dm eff (mb/4 GeV) M eff (GeV) page 27

36 BSM searches at the LHC simple discriminant for SUSY searches: effective mass M eff = E T,miss + 4 i=1 pjet T excess of events with large M eff initial discovery of SUSY Modern LO Monte Carlo tools predict much larger multi-jet background page 28

37 BSM searches at the LHC simple discriminant for SUSY searches: effective mass M eff = E T,miss + 4 i=1 pjet T excess of events with large M eff initial discovery of SUSY Modern LO Monte Carlo tools predict much larger multi-jet background What will disagreement between Monte Carlo and data mean? Need precision NLO calculations to tell! page 28

38 Precision calculations for BSM physics at the LHC no excess over SM expectations 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) determine masses & spins page 29

39 Precision calculations for BSM physics at the LHC no excess over SM expectations exclude models / set limits on model parameters CDF Run II Preliminary -1 L=2. fb 6 Theoretical uncertainties included in the calculation of the limit observed limit 95% C.L. expected limit ) UA2 A =, tanβ=5, µ< M q ~ = M g ~ (GeV/c 3 UA1 no msugra solution M~ q 2 FNAL Run I 1 LEP M g ~ (GeV/c ) page 3

40 Precision calculations for BSM physics at the LHC no excess over SM expectations exclude models / set limits on model parameters CDF Run II Preliminary -1 L=2. fb Theoretical uncertainties not included NLO Cross Section [pb] 1 NLO: PROSPINO CTEQ6.1M in the calculation of the limit syst. uncert. (PDF Ren.) observed limit 95% C.L. expected limit 95% C.L M g ~ = M q ~ M g ~ [GeV/c ] page 31

41 Precision calculations for BSM physics at the LHC no excess over SM expectations exclude models / set limits on model parameters Prospino: PROduction of Suspersymmetric Particles In NlO [Beenakker, Höpker, MK, Plehn, Spira, Zerwas ( 95-8)] page 32

42 Precision calculations for BSM physics at the LHC excess in inclusive jets + E T,miss signal (early LHC phase) discriminate BSM models page 33

43 Precision calculations for BSM physics at the LHC excess in inclusive jets + E T,miss signal (early LHC phase) discriminate BSM models look-alike models (Hubisz, Lykken, Pierini, Spiropulu) ] 2 mass [GeV/c LH2 NM6 NM4 CS uh i Z H i dh W H ~ d L u~ R u~ ~ L χ 2 d R χ ± 1 ~ l R τ 1 ~ d L u~ u~ R ± χ ~ d L R χ 2 1 χ 2 ~ l R g ~ χ ± 1 τ A H χ 1 χ 1 χ 1 page 33

44 Precision calculations for BSM physics at the LHC excess in inclusive jets + E T,miss signal (early LHC phase) discriminate BSM models look-alike models (Hubisz, Lykken, Pierini, Spiropulu) ] 2 mass [GeV/c uh i Z H A H LH2 NM6 NM4 CS7 i dh W H ~ d L u~ R u~ ~ L χ χ 2 1 d R χ ± 1 ~ l R τ 1 χ 2 χ 1 ~ d L u~ u~ R ± χ ~ d L R 1 χ 2 ~ l R χ 1 g ~ χ ± 1 τ 1 Little Higgs model LH2 and SUSY models NM4 and CS7 give same number of events after cuts twin models LH2 and NM6 (SUSY) have different cross sections and event counts distinguish models with same spectrum but different spins through event count page 33

45 Precision calculations for BSM physics at the LHC excess in inclusive jets + E T,miss signal (early LHC phase) discriminate BSM models ancient wisdom : cross sections depend on spin, e.g. q + q q + q ˆσ LO [q q q q] = α2 sπ s 4 27 β3 (β 2 = 1 4m 2 /s) page 34

46 Precision calculations for BSM physics at the LHC excess in inclusive jets + E T,miss signal (early LHC phase) discriminate BSM models ancient wisdom : cross sections depend on spin, e.g. q + q q + q 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 1 at the Tevatron page 34

47 Precision calculations for BSM physics at the LHC excess in inclusive jets + E T,miss signal (early LHC phase) discriminate BSM models ancient wisdom : cross sections depend on spin (Kane, Petrov, Shao, Wang) 1 t s t s Cross Section pb D CDF tt mass GeV no production of scalar quarks (assuming same mass and couplings as top... ) page 35

48 Precision calculations for BSM physics at the LHC excess in inclusive jets + E T,miss signal (early LHC phase) discriminate BSM models how to discriminate look-alike models? (Hubisz, Lykken, Pierini, Spiropulu) number of events consider ratios of event counts, e.g. σ(p T > 25, 5,... GeV)/σ systematic uncertainties cancel normalization important (GeV/c) p T page 36

49 Precision calculations for BSM physics at the LHC excess in inclusive jets + E T,miss signal (early LHC phase) discriminate BSM models how to discriminate look-alike models? (Hubisz, Lykken, Pierini, Spiropulu) number of events consider ratios of event counts, e.g. σ(p T > 25, 5,... GeV)/σ systematic uncertainties cancel normalization important (GeV/c) p T NLO affects shape of distributions: K σnlo (pp t t) σ LO (pp t t) 1.4 (p T > 1 GeV) =.5 (p T > 1 GeV) page 36

50 Precision calculations for BSM physics at the LHC excess in inclusive jets + E T,miss signal (early LHC phase) discriminate BSM models how to discriminate look-alike models? (Hubisz, Lykken, Pierini, Spiropulu) number of events consider ratios of event counts, e.g. σ(p T > 25, 5,... GeV)/σ systematic uncertainties cancel normalization important (GeV/c) p T NLO affects shape of distributions: K σnlo (pp t t) σ LO (pp t t) 1.4 (p T > 1 GeV) =.5 (p T > 1 GeV) no proper tools to perform realistic NLO analysis of BSM decay chains page 36

51 Precision calculations for BSM physics at the LHC exploring BSM models (later LHC phase) determine masses & spins Mass measurements from cascade decays, e.g. Allanach et al. 15 Events/1 GeV/1 fb m(ll) (GeV) kinematic endpoint sensitive to mass differences (m max ll ) 2 = (m 2 χ 2 m 2 lr )(m 2 lr m 2 χ 1)/(m 2 lr ) page 37

52 Precision calculations for BSM physics at the LHC exploring BSM models (later LHC phase) determine masses & spins Mass measurements from total rate, e.g. gluino mass in SUSY models with heavy scalars (FP dark matter scenarios) 1 1 σ(pp g g + X) [pb] NLO LO { 785 ± 35 (LO).1 m gluino = 87 ± 15 (NLO) m g [GeV] page 38

53 Precision calculations for BSM physics at the LHC exploring BSM models (later LHC phase) determine masses & spins Mass measurements from total rate, e.g. gluino mass in SUSY models with heavy scalars (FP dark matter scenarios) (Baer, Barger, Shaunghnessy, Summy, Wang) 4 3 TH 1 fb -1 error TH ±15% TH ±15% ±1%BG BG σ (fb) 2 1 LEP2 excluded m gluino = ±8% m g ~ page 39

54 Precision calculations for BSM physics at the LHC exploring BSM models (later LHC phase) determine masses & spins q L 2 no spin correlations: q L l R + (near) 1.5 tree unpol. dσ/dm ql + near χ 2 l R - χ 1 l R - (far) m ql + near [GeV] page 4

55 Precision calculations for BSM physics at the LHC exploring BSM models (later LHC phase) determine masses & spins q L 2 with spin correlations: q L l R + (near) 1.5 tree pol. tree unpol dσ/dm ql + near χ 2 l R - χ 1 l R - (far) m ql + near [GeV] page 41

56 Precision calculations for BSM physics at the LHC exploring BSM models (later LHC phase) determine masses & spins q L 2 with spin correlations: q L l R + (near) 1.5 tree pol. tree unpol dσ/dm ql + near χ 2 l R - χ 1 l R - (far) m ql + near [GeV] cannot determine m ql + near distribution experimentally consider charge asymmetry A = (dσ/dm ql + dσ/dm ql )/(dσ/dm ql + +dσ/dm ql ) page 41

57 Precision calculations for BSM physics at the LHC exploring BSM models (later LHC phase) determine masses & spins q L A (Barr) q L l R + (near).1 χ 2 l R - - l R χ 1 (far) m lq / GeV cannot determine m ql + near distribution experimentally consider charge asymmetry A = (dσ/dm ql + dσ/dm ql )/(dσ/dm ql + +dσ/dm ql ) page 42

58 Precision calculations for BSM physics at the LHC exploring BSM models (later LHC phase) determine masses & spins q L 2 with spin correlations: q L l R + (near) 1.5 tree pol. tree unpol dσ/dm ql + near χ 2 l R - χ 1 l R - (far) m ql + near [GeV] page 43

59 Precision calculations for BSM physics at the LHC exploring BSM models (later LHC phase) determine masses & spins q L 2 with spin NLO: q L l R + (near) 1.5 tree pol. tree unpol NLO pol dσ/dm ql + near χ 2 l R - χ 1 l R - (far) m ql + near [GeV] radiative corrections affect shape of distributions (Horsky, MK, Mück, Zerwas) page 44

60 Precision calculations for BSM physics at the LHC exploring BSM models (later LHC phase) determine masses & spins q L q L l R + (near) 1.5 A (Born) A (NLO) (Horsky, MK, Mück, Zerwas) χ 2 l R - - l R χ 1 (far) M ql consider charge asymmetry A = (dσ/dm ql + dσ/dm ql )/(dσ/dm ql + + dσ/dm ql ) radiative corrections cancel in charge asymmetry page 45

61 Precision calculations for BSM physics at the LHC exploring BSM models (later LHC phase) determine masses & spins consider invariant jet-mass distributions in decay chains like pp g + g q q R + q q L qq χ 1 + qq χ 2 q q g g q q information on gluino spin in jet event shapes (MK, Popenda, Spira, Zerwas) page 46

62 Precision calculations for BSM physics at the LHC exploring BSM models (later LHC phase) determine masses & spins consider invariant jet-mass distributions in decay chains like pp g + g q q R + q q L qq χ 1 + qq χ /σ tot dσ/dm jet ( g( uũ( u χ)) g( uũ( u χ)) [1/GeV] without spin correlations: < M jet >= 116 GeV ũ R ũ R :< M jet >= 116 GeV ũ R ũ L :< M jet >= 12 GeV SPS1a : m g = 67 GeV mũr/l = 547/565 GeV m χ1/2 = 98/184 GeV M jet calulated from the two jets with the lowest p T M jet [GeV] 4 5 information on gluino spin in jet event shapes (MK, Popenda, Spira, Zerwas) page 47

63 Precision calculations for BSM physics at the LHC exploring BSM models (later LHC phase) determine masses & spins... or the number of extra dimensions? consider graviton production in ADD scenarios (Arkani-Hamed, Dimopoulos, Dvali) pp G + jet monojet signature dσ dp miss T Z + jet [pb/gev] δ = 3, M s = 5TeV δ = 4, M s = 5TeV δ = 5, M s = 5TeV p miss T determine number of extra dimensions δ? page 48

64 Precision calculations for BSM physics at the LHC exploring BSM models (later LHC phase) determine masses & spins... or the number of extra dimensions? consider graviton production in ADD scenarios (Arkani-Hamed, Dimopoulos, Dvali) pp G + jet monojet signature dσ dp miss T Z + jet [pb/gev] δ = 3, M s = 5TeV δ = 4, M s = 5TeV δ = 5, M s = 5TeV p miss T spoiled by QCD uncertainties... page 49

65 Precision calculations for BSM physics at the LHC exploring BSM models (later LHC phase) determine masses & spins... or the number of extra dimensions? consider graviton production in ADD scenarios (Arkani-Hamed, Dimopoulos, Dvali) pp G + jet monojet signature LO NLO p T,miss include NLO-QCD corrections (Karg, MK, Li, Zeppenfeld, prelim.) page 5

66 Precision calculations for BSM physics at the LHC exploring BSM models (later LHC phase) determine masses & spins... or the number of extra dimensions? consider graviton production in ADD scenarios (Arkani-Hamed, Dimopoulos, Dvali) pp G + jet monojet signature σ(µ)/σ(µ = p T,miss ) LO NLO P P G + jet (δ = 4, M s = 4TeV) µ/µ include NLO-QCD corrections (Karg, MK, Li, Zeppenfeld, prelim.) page 51

67 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, 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 (Debajyoti Choudhury, Swapan Majhi, V. Ravindran; Yang, Li, Liu, Li; Dreiner, Grab, MK, Trenkel) page 52

68 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, 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 (Debajyoti Choudhury, Swapan Majhi, V. Ravindran; Yang, Li, Liu, Li; Dreiner, Grab, MK, Trenkel) Sparticle decays total rates Sdecay: (Mühlleitner, Djouadi, Mambrini) plus work by many authors only few results for shapes (Drees, Hollik, Xu; Horsky, MK, Mück, Zerwas) page 52

69 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, 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 (Debajyoti Choudhury, Swapan Majhi, V. Ravindran; Yang, Li, Liu, Li; Dreiner, Grab, MK, Trenkel) Sparticle decays total rates Sdecay: (Mühlleitner, Djouadi, Mambrini) plus work by many authors only few results for shapes (Drees, Hollik, Xu; Horsky, MK, Mück, Zerwas) Sparticle production decay: generic BSM cascades (SUSY, UEDs, LH,... ) so far only tree level challenge for LHC theory community... page 52

70 Precision calculations at the LHC: conclusions & outlook... Signal cross sections in the SM and MSSM are (or will rather soon be) known at NLO accuracy theoretical uncertainty 15% for inclusive cross sections larger uncertainty for exclusive observables can predict distributions and observables with cuts in general no parton showers/hadronization page 53

71 Precision calculations at the LHC: conclusions & outlook... Signal cross sections in the SM and MSSM are (or will rather soon be) known at NLO accuracy theoretical uncertainty 15% for inclusive cross sections larger uncertainty for exclusive observables can predict distributions and observables with cuts in general no parton showers/hadronization Progress in matching NLO calculations with parton showers and hadronization page 53

72 Precision calculations at the LHC: conclusions & outlook... Signal cross sections in the SM and MSSM are (or will rather soon be) known at NLO accuracy theoretical uncertainty 15% for inclusive cross sections larger uncertainty for exclusive observables can predict distributions and observables with cuts in general no parton showers/hadronization Progress in matching NLO calculations with parton showers and hadronization EWK corrections: important for high accuracy or scales M W,Z page 53

73 Precision calculations at the LHC: conclusions & outlook... Signal cross sections in the SM and MSSM are (or will rather soon be) known at NLO accuracy theoretical uncertainty 15% for inclusive cross sections larger uncertainty for exclusive observables can predict distributions and observables with cuts in general no parton showers/hadronization Progress in matching NLO calculations with parton showers and hadronization EWK corrections: important for high accuracy or scales M W,Z Many backgrounds (multi-leg processes) are only know at LO (Need breakthrough in techniques to do pp > 4 partons at NLO?) page 53

74 Precision calculations at the LHC: conclusions & outlook... Signal cross sections in the SM and MSSM are (or will rather soon be) known at NLO accuracy theoretical uncertainty 15% for inclusive cross sections larger uncertainty for exclusive observables can predict distributions and observables with cuts in general no parton showers/hadronization Progress in matching NLO calculations with parton showers and hadronization EWK corrections: important for high accuracy or scales M W,Z Many backgrounds (multi-leg processes) are only know at LO (Need breakthrough in techniques to do pp > 4 partons at NLO?) First LHC data will allow us to focus on the relevant processes... page 53