MSSM Phenomenology at the LHC

Transcription

1 MSSM Phenomenology at the LHC Manuel Drees Bonn University & Bethe Center for Theoretical Physics MSSM at the LHC p. 1/35

2 Contents 1 Introduction: Finetuning and Weak Scale Supersymmetry MSSM at the LHC p. 2/35

3 Contents 1 Introduction: Finetuning and Weak Scale Supersymmetry 2 The Basics (a) q, g Production Channels (b) g, q Decays MSSM at the LHC p. 2/35

4 Contents 1 Introduction: Finetuning and Weak Scale Supersymmetry 2 The Basics (a) q, g Production Channels (b) g, q Decays 3 Mass Reach MSSM at the LHC p. 2/35

5 Contents 1 Introduction: Finetuning and Weak Scale Supersymmetry 2 The Basics (a) q, g Production Channels (b) g, q Decays 3 Mass Reach 4 Examples for Analyses (a) Model Discrimination (b) SUSY Rapidity Gaps MSSM at the LHC p. 2/35

6 Contents 1 Introduction: Finetuning and Weak Scale Supersymmetry 2 The Basics (a) q, g Production Channels (b) g, q Decays 3 Mass Reach 4 Examples for Analyses (a) Model Discrimination (b) SUSY Rapidity Gaps 5 Summary MSSM at the LHC p. 2/35

7 Introduction: Finetuning Problem In SM: loop corrections to squared Higgs boson mass diverge quadratically! W,Z t φ φ + φ φ t +... MSSM at the LHC p. 3/35

8 Introduction: Finetuning Problem In SM: loop corrections to squared Higgs boson mass diverge quadratically! W,Z t φ φ + φ φ t +... δm 2 φ = Λ2 8π 2 ( 3λ 2 t + 2g ) Λ: quadratic momentum cut off MSSM at the LHC p. 3/35

9 Introduction: Finetuning Problem In SM: loop corrections to squared Higgs boson mass diverge quadratically! W,Z t φ φ + φ φ t +... δm 2 φ = Λ2 8π 2 ( 3λ 2 t + 2g ) Λ: quadratic momentum cut off = Difficult to keep m φ much below highest energy where SM is applicable! MSSM at the LHC p. 3/35

10 SUSY to the Rescue! Supersymmetry postulates existence of superpartners with spin differing by 1/2 unit, same interactions MSSM at the LHC p. 4/35

11 SUSY to the Rescue! Supersymmetry postulates existence of superpartners with spin differing by 1/2 unit, same interactions = additional diagrams exist: φ t L,R λ 2 t φ + g φ g φ φ +... W MSSM at the LHC p. 4/35

12 SUSY to the Rescue! Supersymmetry postulates existence of superpartners with spin differing by 1/2 unit, same interactions = additional diagrams exist: φ t L,R λ 2 t φ + g φ g φ φ +... W These cancel the quadratic divergencies! MSSM at the LHC p. 4/35

13 SUSY to the Rescue! Supersymmetry postulates existence of superpartners with spin differing by 1/2 unit, same interactions = additional diagrams exist: φ t L,R λ 2 t φ + g φ g φ φ +... W These cancel the quadratic divergencies! δm 2 φ 1 8π 2 [ λ 2 t ( m 2 t ) ( m2 t + g 2 Mf 2 W MW) ] MSSM at the LHC p. 4/35

14 SUSY to the Rescue! Supersymmetry postulates existence of superpartners with spin differing by 1/2 unit, same interactions = additional diagrams exist: φ t L,R λ 2 t φ + g φ g φ φ +... W These cancel the quadratic divergencies! δm 2 φ 1 8π 2 [ λ 2 t ( m 2 t ) ( ] m2 t + g 2 Mf 2 W MW) Want δm 2 φ (100 GeV)2 = need sparticle masses < 1 TeV! MSSM at the LHC p. 4/35

15 Remarks Smaller sparticle masses are better: finetuning m 2 t,m2 f W! MSSM at the LHC p. 5/35

16 Remarks Smaller sparticle masses are better: finetuning m 2 t,m2 f W! Argument strictly only applies to t, W, Z masses MSSM at the LHC p. 5/35

17 Remarks Smaller sparticle masses are better: finetuning m 2 t,m2 f W! Argument strictly only applies to t, W, Z masses But: g couples strongly to t : m g m t 2 not possible Get (new) term δm 2 φ g2 Y Y φ 8π 2 f Y fm 2 f (U(1) Y D term) = Need all sfermions below (few) TeV! Or cancellations. MSSM at the LHC p. 5/35

18 Remarks Smaller sparticle masses are better: finetuning m 2 t,m2 f W! Argument strictly only applies to t, W, Z masses But: g couples strongly to t : m g m t 2 not possible Get (new) term δm 2 φ g2 Y Y φ 8π 2 f Y fm 2 f (U(1) Y D term) = Need all sfermions below (few) TeV! Or cancellations. Calculation holds for mass in potential, not physical mass. MSSM at the LHC p. 5/35

19 Other reasons for weak scale SUSY Muon magnetic moment: expt. 3 sigma above SM prediction; can be fixed via light µ, ν µ, gauginos. MSSM at the LHC p. 6/35

20 Other reasons for weak scale SUSY Muon magnetic moment: expt. 3 sigma above SM prediction; can be fixed via light µ, ν µ, gauginos. Unification of gauge couplings: Logarithmically sensitive to sparticle masses MSSM at the LHC p. 6/35

21 Other reasons for weak scale SUSY Muon magnetic moment: expt. 3 sigma above SM prediction; can be fixed via light µ, ν µ, gauginos. Unification of gauge couplings: Logarithmically sensitive to sparticle masses Dark Matter: can tolerate m χ 0 1 > 1 TeV. MSSM at the LHC p. 6/35

22 Basics of MSSM Phenomenology SUSY signals at LHC dominated by production and decay of squarks and gluinos! MSSM at the LHC p. 7/35

23 Basics of MSSM Phenomenology SUSY signals at LHC dominated by production and decay of squarks and gluinos! Partonic cross sections:(lo QCD; m g = m q = ŝ/8; n f = 5 deg. squarks) Process ˆσ [ πα 2 s ŝ q i q j q q 0.30δ ij gg q q 0.36 q i q j q q δ ij q q g g 0.16 qg q g 1.21 gg g g 2.45 ] MSSM at the LHC p. 7/35

24 Basics of MSSM Phenomenology SUSY signals at LHC dominated by production and decay of squarks and gluinos! Partonic cross sections:(lo QCD; m g = m q = ŝ/8; n f = 5 deg. squarks) Process ˆσ [ πα 2 s ŝ q i q j q q 0.30δ ij gg q q 0.36 q i q j q q δ ij q q g g 0.16 qg q g 1.21 gg g g 2.45 Reminiscent of hierarchy of QCD 2 2 cross sections: SUSY at work! ] MSSM at the LHC p. 7/35

25 Partonic cross sections (cont d) First computed in 1980 s. Harrison & Llewellyn Smith 1983; Dawson, Eichten & Quigg Refinements: NLO QCD corrections Beenakker, Höpker, Spira, Zerwas 1996: k factor [1.0, 1.5] for q production, [1.3, 2.5] for g g. MSSM at the LHC p. 8/35

26 Partonic cross sections (cont d) First computed in 1980 s. Harrison & Llewellyn Smith 1983; Dawson, Eichten & Quigg Refinements: NLO QCD corrections Beenakker, Höpker, Spira, Zerwas 1996: k factor [1.0, 1.5] for q production, [1.3, 2.5] for g g. Electroweak tree level contributions Bornhauser, Drees, Dreiner & Kim 2008: up to 20% in msugra, up to 50% in general MSSM at the LHC p. 8/35

27 Partonic cross sections (cont d) First computed in 1980 s. Harrison & Llewellyn Smith 1983; Dawson, Eichten & Quigg Refinements: NLO QCD corrections Beenakker, Höpker, Spira, Zerwas 1996: k factor [1.0, 1.5] for q production, [1.3, 2.5] for g g. Electroweak tree level contributions Bornhauser, Drees, Dreiner & Kim 2008: up to 20% in msugra, up to 50% in general Electroweak one loop corrections Hollik & Mirabella 2008; Hollik, Mirabella & Trenkel 2008; Gerner, Hollik, Mirabella & Trenkel 2010 MSSM at the LHC p. 8/35

28 Partonic cross sections (cont d) First computed in 1980 s. Harrison & Llewellyn Smith 1983; Dawson, Eichten & Quigg Refinements: NLO QCD corrections Beenakker, Höpker, Spira, Zerwas 1996: k factor [1.0, 1.5] for q production, [1.3, 2.5] for g g. Electroweak tree level contributions Bornhauser, Drees, Dreiner & Kim 2008: up to 20% in msugra, up to 50% in general Electroweak one loop corrections Hollik & Mirabella 2008; Hollik, Mirabella & Trenkel 2008; Gerner, Hollik, Mirabella & Trenkel 2010 QCD threshold resummation Langenfeld & Moch 2009; Kulesza & Motyka 2009; Beenakker, Brensing, Krämer, Kulesza, Laenen & Niessen 2009; Hagiwara & Yokoya 2009; Beneke, Falgari & Schwinn 2010 MSSM at the LHC p. 8/35

29 Partonic cross sections (cont d) First computed in 1980 s. Harrison & Llewellyn Smith 1983; Dawson, Eichten & Quigg Refinements: NLO QCD corrections Beenakker, Höpker, Spira, Zerwas 1996: k factor [1.0, 1.5] for q production, [1.3, 2.5] for g g. Electroweak tree level contributions Bornhauser, Drees, Dreiner & Kim 2008: up to 20% in msugra, up to 50% in general Electroweak one loop corrections Hollik & Mirabella 2008; Hollik, Mirabella & Trenkel 2008; Gerner, Hollik, Mirabella & Trenkel 2010 QCD threshold resummation Langenfeld & Moch 2009; Kulesza & Motyka 2009; Beenakker, Brensing, Krämer, Kulesza, Laenen & Niessen 2009; Hagiwara & Yokoya 2009; Beneke, Falgari & Schwinn 2010 Flavor effects: See talk by Porod MSSM at the LHC p. 8/35

30 pp Cross Sections σ(pp S 1 S 2 X) = partons i,j 1 1 dτ s/s min τ ˆσ(ij S 1 S2 )(ŝ = τs). dx x f i p(x,q 2 )f j p ( τ x,q2 ) Orange: partonic flux function; depends on i,j,τ, (Q 2 = ŝ). MSSM at the LHC p. 9/35

31 Flux Functions parton flux 1e+06 1e e-05 1e-06 gg _ q i q i MRSA, Q 2 = s qg qq s [GeV] MSSM at the LHC p. 10/35

32 Flux Functions parton flux 1e+06 1e e-05 1e-06 gg _ q i q i MRSA, Q 2 = s qg qq s [GeV] Fluxes drop off faster for m g, q > TeV! MSSM at the LHC p. 10/35

33 Total NLO q, g cross sections at s = 7 TeV Baer, Barger, Lessa, Tata LHC7 - m q ~ = m g ~ σtotal σ(q ~ ~ q ) σ(g ~ ~ g ) σ(q ~ ~ g ) (fb) σ NLO m~ g (GeV) LHC7 - m q ~ = 2m g ~ σtotal σ(q ~ ~ q ) σ(g ~ ~ g ) σ(q ~ ~ g ) (fb) σ NLO m~ g (GeV) MSSM at the LHC p. 11/35

34 q, g vs ELW Gaugino Production Assume gaugino mass unification = m fw m g /3 MSSM at the LHC p. 12/35

35 q, g vs ELW Gaugino Production Assume gaugino mass unification = m fw m g /3 Partonic cross sections similar: α2 s m 2 g = α2 W m 2 f W MSSM at the LHC p. 12/35

36 q, g vs ELW Gaugino Production Assume gaugino mass unification = m fw m g /3 Partonic cross sections similar: α2 s = α2 m 2 g W m 2 W f Fluxes: q q flux at ŝ = 8m fw m g vs. qq + q q + qg + gg flux at ŝ = 8m g : MSSM at the LHC p. 12/35

37 q, g vs ELW Gaugino Production Assume gaugino mass unification = m fw m g /3 Partonic cross sections similar: α2 s = α2 m 2 g W m 2 W f Fluxes: q q flux at ŝ = 8m fw m g vs. qq + q q + qg + gg flux at ŝ = 8m g : S/B better for q, g production than for elw χ χ production, if χ decays hadronically MSSM at the LHC p. 12/35

38 q, g vs ELW Gaugino Production Assume gaugino mass unification = m fw m g /3 Partonic cross sections similar: α2 s = α2 m 2 g W m 2 W f Fluxes: q q flux at ŝ = 8m fw m g vs. qq + q q + qg + gg flux at ŝ = 8m g : S/B better for q, g production than for elw χ χ production, if χ decays hadronically Hence χ χ production only relevant for large q, g mass (earlier if m q > m g ): Needs large luminosity. MSSM at the LHC p. 12/35

39 q, g vs ELW Gaugino Production Assume gaugino mass unification = m fw m g /3 Partonic cross sections similar: α2 s = α2 m 2 g W m 2 W f Fluxes: q q flux at ŝ = 8m fw m g vs. qq + q q + qg + gg flux at ŝ = 8m g : S/B better for q, g production than for elw χ χ production, if χ decays hadronically Hence χ χ production only relevant for large q, g mass (earlier if m q > m g ): Needs large luminosity. Situation different at Tevatron: pure valence quark contribution to q q flux! MSSM at the LHC p. 12/35

40 Ratio q q flux to total flux ratio qq _ (s /8) / all(s ) 100 Tevatron flux ratio 10 LHC s [GeV] MSSM at the LHC p. 13/35

41 Decays of Squarks and Gluinos If LSP is stable: must be neutral. If Dark Matter: should be lightest neutralino χ 0 1. G as LSP: see GMSB MSSM at the LHC p. 14/35

42 Decays of Squarks and Gluinos If LSP is stable: must be neutral. If Dark Matter: should be lightest neutralino χ 0 1. G as LSP: see GMSB If gaugino masses unify (msugra, mgmsb): m g : m fw : m B 6 : 2 : 1 at SUSY mass scale MSSM at the LHC p. 14/35

43 Decays of Squarks and Gluinos If LSP is stable: must be neutral. If Dark Matter: should be lightest neutralino χ 0 1. G as LSP: see GMSB If gaugino masses unify (msugra, mgmsb): m g : m fw : m B 6 : 2 : 1 at SUSY mass scale m q > 0.75m g, or m2 q turns negative at a rather low energy scale Ellwanger 1984 MSSM at the LHC p. 14/35

44 Decays of Squarks and Gluinos If LSP is stable: must be neutral. If Dark Matter: should be lightest neutralino χ 0 1. G as LSP: see GMSB If gaugino masses unify (msugra, mgmsb): m g : m fw : m B 6 : 2 : 1 at SUSY mass scale m q > 0.75m g, or m2 q turns negative at a rather low energy scale Ellwanger 1984 Hence for gaugino mass unification: MSSM at the LHC p. 14/35

45 Decays of Squarks and Gluinos If LSP is stable: must be neutral. If Dark Matter: should be lightest neutralino χ 0 1. G as LSP: see GMSB If gaugino masses unify (msugra, mgmsb): m g : m fw : m B 6 : 2 : 1 at SUSY mass scale m q > 0.75m g, or m2 q turns negative at a rather low energy scale Ellwanger 1984 Hence for gaugino mass unification: q, g W, B decays possible MSSM at the LHC p. 14/35

46 Decays of Squarks and Gluinos If LSP is stable: must be neutral. If Dark Matter: should be lightest neutralino χ 0 1. G as LSP: see GMSB If gaugino masses unify (msugra, mgmsb): m g : m fw : m B 6 : 2 : 1 at SUSY mass scale m q > 0.75m g, or m2 q turns negative at a rather low energy scale Ellwanger 1984 Hence for gaugino mass unification: q, g W, B decays possible W B decays possible MSSM at the LHC p. 14/35

47 If m q > m g : q gq dominant MSSM at the LHC p. 15/35

48 If m q > m g : q gq dominant B( q Wq) 3α W αs squarks I3, q 2 : only for SU(2) doublet, L MSSM at the LHC p. 15/35

49 If m q > m g : q gq dominant B( q Wq) 3α W αs squarks I3, q 2 : only for SU(2) doublet, L B( q Bq) α Y α s Y 2 q MSSM at the LHC p. 15/35

50 If m q > m g : q gq dominant B( q Wq) 3α W αs squarks I3, q 2 : only for SU(2) doublet, L B( q Bq) α Y α s Y 2 q g q q W, q q B, with ratio of Brs 3α W /α Y if m ql m qr. MSSM at the LHC p. 15/35

51 If m g > m q : q L Wq dominant; ratio W ± : W 0 2 : 1 q L Bq (few %): Y ql = 1/6 MSSM at the LHC p. 16/35

52 If m g > m q : q L Wq dominant; ratio W ± : W 0 2 : 1 q L Bq (few %): Y ql = 1/6 q R Bq dominant: I 3, qr = 0. MSSM at the LHC p. 16/35

53 If m g > m q : q L Wq dominant; ratio W ± : W 0 2 : 1 q L Bq (few %): Y ql = 1/6 q R Bq dominant: I 3, qr = 0. g q L,R q; about equally into q L and q R if m ql m qr. But rather close to edge of phase space! MSSM at the LHC p. 16/35

54 If m g > m q : q L Wq dominant; ratio W ± : W 0 2 : 1 q L Bq (few %): Y ql = 1/6 q R Bq dominant: I 3, qr = 0. g q L,R q; about equally into q L and q R if m ql m qr. But rather close to edge of phase space! Quite often: mũ, d, s, c > m b, t (RG effects of b,t Yukawas; L R mixing) = g b ( ) b, t ( ) t + cc often dominant! MSSM at the LHC p. 16/35

55 If m W > m B (msugra, mgmsb) W Bf f via real or virtual f, Higgs, W ± /Z 0 exchange. MSSM at the LHC p. 17/35

56 If m W > m B (msugra, mgmsb) W Bf f via real or virtual f, Higgs, W ± /Z 0 exchange. Brs strongly depend on many parameters MSSM at the LHC p. 17/35

57 If m W > m B (msugra, mgmsb) W Bf f via real or virtual f, Higgs, W ± /Z 0 exchange. Brs strongly depend on many parameters If m fw > m l : W 0 l + l B via two 2 body decays! MSSM at the LHC p. 17/35

58 If m W > m B (msugra, mgmsb) W Bf f via real or virtual f, Higgs, W ± /Z 0 exchange. Brs strongly depend on many parameters If m fw > m l : W 0 l + l B via two 2 body decays! But: if m fw > m ll : W τ1 τ dominates! ( τ 1 is lighter, has sizable τ L component.) MSSM at the LHC p. 17/35

59 Typically (mgmsb, much of msugra) Higgsino mass µ > m fw > m B MSSM at the LHC p. 18/35

60 Typically (mgmsb, much of msugra) Higgsino mass µ > m fw > m B = 0 m χ 3 0 m χ 4 ± m χ µ higgsino like 2 0 m χ 2 ± m χ m f 1 W wino like 0 m χ 1 0 m χ 2 /2 bino like. MSSM at the LHC p. 18/35

61 Typically (mgmsb, much of msugra) Higgsino mass µ > m fw > m B = 0 m χ 3 0 m χ 4 ± m χ µ higgsino like 2 0 m χ 2 ± m χ m f 1 W wino like 0 m χ 1 0 m χ 2 /2 bino like. But: µ m fw or µ m B possible even in msugra: gives more complicated mixing patterns! MSSM at the LHC p. 18/35

62 Examples of final states (many possibilities!) qq q R q R (q χ 0 1 )(q χ0 1 ) 2 very energetic jets (E T > m qr /2), large missing E T ( > m qr / 2). MSSM at the LHC p. 19/35

63 Examples of final states (many possibilities!) qq q R q R (q χ 0 1 )(q χ0 1 ) 2 very energetic jets (E T > m qr /2), large missing E T ( > m qr / 2). qq q R q L (q χ 0 1 )(q χ0 2 ) (q χ0 1 )(q χ0 1 l+ l ) 2 jets, l + l pair and missing E T. MSSM at the LHC p. 19/35

64 Examples of final states (many possibilities!) qq q R q R (q χ 0 1 )(q χ0 1 ) 2 very energetic jets (E T > m qr /2), large missing E T ( > m qr / 2). qq q R q L (q χ 0 1 )(q χ0 2 ) (q χ0 1 )(q χ0 1 l+ l ) 2 jets, l + l pair and missing E T. ud ũ L dl (d χ + 1 )(u χ 1 ) (d χ0 1 l+ ν l )(u χ 0 1l ν l ) 2 jets, l + l pair and missing E T MSSM at the LHC p. 19/35

65 Examples of final states (many possibilities!) qq q R q R (q χ 0 1 )(q χ0 1 ) 2 very energetic jets (E T > m qr /2), large missing E T ( > m qr / 2). qq q R q L (q χ 0 1 )(q χ0 2 ) (q χ0 1 )(q χ0 1 l+ l ) 2 jets, l + l pair and missing E T. ud ũ L dl (d χ + 1 )(u χ 1 ) (d χ0 1 l+ ν l )(u χ 0 1l ν l ) 2 jets, l + l pair and missing E T ug ũ L g (d χ + 1 )( t 1 t) (dl + ν l χ 0 1 )( bs c χ 0 1 bl + ν l ) 5 jets (incl. 2 b jets), l + l + pair and missing E T. MSSM at the LHC p. 19/35

66 Classification of events Standard classifiers are: Number of jets n j, number of charged leptons n l (l = e,µ) MSSM at the LHC p. 20/35

67 Classification of events Standard classifiers are: Number of jets n j, number of charged leptons n l (l = e,µ) If n l = 2: distinguish like sign (LS) pairs and opposite sign (OS) pairs, depending on charge; among latter, opposite sign same flavor (OSSF) is subcategory. MSSM at the LHC p. 20/35

68 Classification of events Standard classifiers are: Number of jets n j, number of charged leptons n l (l = e,µ) If n l = 2: distinguish like sign (LS) pairs and opposite sign (OS) pairs, depending on charge; among latter, opposite sign same flavor (OSSF) is subcategory. Number of b tags n b is occasionally used MSSM at the LHC p. 20/35

69 Classification of events Standard classifiers are: Number of jets n j, number of charged leptons n l (l = e,µ) If n l = 2: distinguish like sign (LS) pairs and opposite sign (OS) pairs, depending on charge; among latter, opposite sign same flavor (OSSF) is subcategory. Number of b tags n b is occasionally used In addition, could look for: τ candidates, via τ ν τ + hadrons: e.g. from χ ± 1 τ ± 1 ν τ τ ± χ 0 1 ν τ. Z 0 candidates, via Z 0 l l + : e.g. from χ 0 i χ0 j<i Z0 top candidates, via top tagging : e.g. from g t 1 t Higgs candidates, via h b b: e.g. from χ 0 i χ0 j<i h MSSM at the LHC p. 20/35

70 msugra CMSSM Most widely studied SUSY framework of SUSY. Defined by: Common scalar mass m 0 Common gaugino mass m 1/2 Common trilinear scalar interaction A 0 at scale of Grand Unification M X GeV. MSSM at the LHC p. 21/35

71 msugra CMSSM Most widely studied SUSY framework of SUSY. Defined by: Common scalar mass m 0 Common gaugino mass m 1/2 Common trilinear scalar interaction A 0 at scale of Grand Unification M X GeV. Bilinear scalar parameter B 0 assumed independent of A 0 ; traded for ratio of vevs tanβ MSSM at the LHC p. 21/35

72 msugra CMSSM Most widely studied SUSY framework of SUSY. Defined by: Common scalar mass m 0 Common gaugino mass m 1/2 Common trilinear scalar interaction A 0 at scale of Grand Unification M X GeV. Bilinear scalar parameter B 0 assumed independent of A 0 ; traded for ratio of vevs tanβ µ determined via (radiative) electroweak symmetry breaking Ibáñez & Ross 1982 µ > 0 preferred by g µ 2, b sγ. MSSM at the LHC p. 21/35

73 msugra CMSSM Most widely studied SUSY framework of SUSY. Defined by: Common scalar mass m 0 Common gaugino mass m 1/2 Common trilinear scalar interaction A 0 at scale of Grand Unification M X GeV. Bilinear scalar parameter B 0 assumed independent of A 0 ; traded for ratio of vevs tanβ µ determined via (radiative) electroweak symmetry breaking Ibáñez & Ross 1982 µ > 0 preferred by g µ 2, b sγ. Assume χ 0 1 is stable LSP: DM candidate! (See Dutta s talk.) MSSM at the LHC p. 21/35

74 LHC reach Reach defined by: require S > 5 B, S > 0.2B, at least 5 signal events. Consider many channels, optimize jet and missing E T cuts within each channel; take best channel. No combination of channels! (Unlike Tevatron SM Higgs search.) From: Baer, Barger, Lessa & Tata 2009/10 MSSM at the LHC p. 22/35

75 Optimized reach at s = 7 TeV (GeV) m 1/ A 0 = 0, tanβ = 45, µ > 0, m t τ LSP LHC7 - All Channels 111 GeV = GeV LEP excluded 114 GeV 1.2 TeV 1 TeV 800 GeV 600 GeV 500 GeV 1400 m g ~ m h m 0 (GeV) -1 2 fb 1 fb fḇ 0.1 fb (GeV) m g ~ MSSM at the LHC p. 23/35

76 Reach at s = 7 TeV, different channels (GeV) m 1/ A 0 = 0, tanβ = 45, µ > 0, m t τ LSP All n(l) = 1 n(b) 2 SS n(l) = GeV 500 GeV -1 LHC7 - Channel Reach at 1 fb OS = GeV LEP excluded 1.2 TeV 1 TeV 800 GeV m 0 (GeV) (GeV) m g ~ MSSM at the LHC p. 24/35

77 Optimized reach at s = 10 TeV N jets 2 (with E T miss cuts, optimized) m 1/2 (GeV) fb -1 (ofit) 1000 fb -1 (ofit) 100 fb fb fb -1 1 fb m 0 (GeV) MSSM at the LHC p. 25/35

78 Optimized reach at s = 14 TeV N jets 2 (with E T miss cuts, optimized) m 1/2 (GeV) fb -1 (ofit) 1000 fb -1 (ofit) 100 fb fb fb -1 1 fb m 0 (GeV) MSSM at the LHC p. 26/35

79 msugra Reach table: m g reach in TeV s [TeV] Ldt [fb 1 ] m q < m g m q m g to 4.5? MSSM at the LHC p. 27/35

80 Remarks Usually best reach in pure jets plus missing E T channel. In SM, missing E T comes from neutrinos, which are frequently produced together with charged leptons (W +jets, t t). MSSM at the LHC p. 28/35

81 Remarks Usually best reach in pure jets plus missing E T channel. In SM, missing E T comes from neutrinos, which are frequently produced together with charged leptons (W +jets, t t). But: no optimization of leptonic observables attempted! MSSM at the LHC p. 28/35

82 Remarks Usually best reach in pure jets plus missing E T channel. In SM, missing E T comes from neutrinos, which are frequently produced together with charged leptons (W +jets, t t). But: no optimization of leptonic observables attempted! For natural sparticle masses: expect signals in many channels! MSSM at the LHC p. 28/35

83 Reach in Other Scenarios mgmsb (has gravitino LSP): at least as good, often better (hard, isolated photons or long lived charged sleptons) Baer, Mercadante, Tata, Wang 2000 MSSM at the LHC p. 29/35

84 Reach in Other Scenarios mgmsb (has gravitino LSP): at least as good, often better (hard, isolated photons or long lived charged sleptons) Baer, Mercadante, Tata, Wang 2000 mamsb: comparable; better, if long lived χ ± 1 detected Baer, Mizukoshi & Tata 2000 can be MSSM at the LHC p. 29/35

85 Reach in Other Scenarios mgmsb (has gravitino LSP): at least as good, often better (hard, isolated photons or long lived charged sleptons) Baer, Mercadante, Tata, Wang 2000 mamsb: comparable; better, if long lived χ ± 1 detected Baer, Mizukoshi & Tata 2000 can be Explicit R parity breaking: Improves reach if χ 0 1 l+ l ν; worse reach for msugra like searches if χ 0 1 udd Baer, Chen & Tata : But: did not consider new single q production channels; new jet substructure methods to find fat jets from χ 0 1 decay. Butterworth, Ellis, Raklev & Salam Certainly can probe m g < 1 TeV at s = 14 TeV with 10 fb 1. MSSM at the LHC p. 29/35

86 Example of Model Discrimination Consider SO(10) model with 2 intermediate scales: SO(10) SU(4) SU(2) L SU(2) R SU(3) C U(1) B L SU(2) L SU(2) R SU(3) C SU(2) L U(1) Y Aulakh, Bajc, Melfo, Rasin & Senjanovic 2000 MSSM at the LHC p. 30/35

87 Example of Model Discrimination Consider SO(10) model with 2 intermediate scales: SO(10) SU(4) SU(2) L SU(2) R SU(3) C U(1) B L SU(2) L SU(2) R SU(3) C SU(2) L U(1) Y Aulakh, Bajc, Melfo, Rasin & Senjanovic 2000 Has extra terms in high scale superpotential (related to ν R masses) MSSM at the LHC p. 30/35

88 Example of Model Discrimination Consider SO(10) model with 2 intermediate scales: SO(10) SU(4) SU(2) L SU(2) R SU(3) C U(1) B L SU(2) L SU(2) R SU(3) C SU(2) L U(1) Y Aulakh, Bajc, Melfo, Rasin & Senjanovic 2000 Has extra terms in high scale superpotential (related to ν R masses) = reduced m t, m b ( 2% effect) MSSM at the LHC p. 30/35

89 Example of Model Discrimination Consider SO(10) model with 2 intermediate scales: SO(10) SU(4) SU(2) L SU(2) R SU(3) C U(1) B L SU(2) L SU(2) R SU(3) C SU(2) L U(1) Y Aulakh, Bajc, Melfo, Rasin & Senjanovic 2000 Has extra terms in high scale superpotential (related to ν R masses) = reduced m t, m b ( 2% effect) = reduced µ (by 10%): reduced m χ 0 3, m χ 0 4, m χ ± 2 ; enhanced gaugino higgsino mixing MSSM at the LHC p. 30/35

90 Example of Model Discrimination Consider SO(10) model with 2 intermediate scales: SO(10) SU(4) SU(2) L SU(2) R SU(3) C U(1) B L SU(2) L SU(2) R SU(3) C SU(2) L U(1) Y Aulakh, Bajc, Melfo, Rasin & Senjanovic 2000 Has extra terms in high scale superpotential (related to ν R masses) = reduced m t, m b ( 2% effect) = reduced µ (by 10%): reduced m χ 0 3, m χ 0 4, m χ ± 2 ; enhanced gaugino higgsino mixing = significantly increased B( g Z 0 + X)! (7.6% vs. 4.3% or 5.0%) MD, Kim, Park 2010 MSSM at the LHC p. 30/35

91 Subtracted M l+ l distribution (m 0 M 1/2 ) Events/10 GeV/300fb SO(10) msugra 2b msugra 2a Invariant mass (GeV) SO(10) has significantly more pronounced Z 0 peak MSSM at the LHC p. 31/35

92 Subtracted M l+ l distribution (m 0 M 1/2 ) Events/10 GeV/300fb SO(10) msugra 2b msugra 2a Invariant mass (GeV) SO(10) has significantly more pronounced Z 0 peak SO(10) model also has more like sign di lepton events: 492 vs. 422 (434). MSSM at the LHC p. 31/35

93 SUSY and QCD Bornhauser, MD, Dreiner, Kim 2009 qq q q can proceed via g (CNS: color non singlet) and W, B (CS: color singlet) exchange. MSSM at the LHC p. 32/35

94 SUSY and QCD Bornhauser, MD, Dreiner, Kim 2009 qq q q can proceed via g (CNS: color non singlet) and W, B (CS: color singlet) exchange. CS exchange: no gluon emission between squarks CNS exchange: gluons emitted preferentially between squarks MSSM at the LHC p. 32/35

95 SUSY and QCD Bornhauser, MD, Dreiner, Kim 2009 qq q q can proceed via g (CNS: color non singlet) and W, B (CS: color singlet) exchange. CS exchange: no gluon emission between squarks CNS exchange: gluons emitted preferentially between squarks Effect biggest for q L q L production ( W exchange) = look for events with 2 hard jets, 2 leptons with same charge, missing E T e.g. uu ũ L ũ L ( χ + 1 d)( χ+ 1 d) (l+ ν l χ 0 1 d)(l + ν l χ 0 1 d) Additional leptons allowed. Require rapidity distance δη 3.0 MSSM at the LHC p. 32/35

96 HERWIG: E T between the hard jets (SPS1a ) # Events qcd contribution qcd+ew contribution PYTHIA: # Events E T of particles[gev] qcd contribution qcd+ew contribution E T of particles[gev] MSSM at the LHC p. 33/35

97 Softer jets between the hard jets (SPS1a ) HERWIG: 0.6 gap ET,jet,max gap E T,jet,max /GeV gap fraction of events with ET,jet PYTHIA: 0.6 gap ET,jet,max gap E T,jet,max /GeV MSSM at the LHC p. 34/35 gap fraction of events with ET,jet

98 Summary LHC will test idea of weak scale Supersymmetry decisively! MSSM at the LHC p. 35/35

99 Summary LHC will test idea of weak scale Supersymmetry decisively! Generally will have signals in many different final states: offers many possibilities to distinguish between models by counting events! Can be combined with kinematic methods. (See Dutta s talk) MSSM at the LHC p. 35/35

100 Summary LHC will test idea of weak scale Supersymmetry decisively! Generally will have signals in many different final states: offers many possibilities to distinguish between models by counting events! Can be combined with kinematic methods. (See Dutta s talk) For detailed analyses: sometimes have to worry mundane QCD uncertainties (e.g. HERWIG vs. PYTHIA) MSSM at the LHC p. 35/35