SUSY-particle and MSSM Higgs production at the LHC

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1 Frontiers in QCD, DESY Hambur, September 2006 SUSY-particle and MSSM His production at the LHC Michael Krämer (RWTH Aachen) We want to discover and explore models of new physics at the LHC determine masses, quantum numbers, couplins by comparin theory and data need accurate theoretical predictions includin hiher-order corrections Michael Krämer Pae 1 Frontiers in QCD, September 2006

2 The hierarchy problem: why is M His M Planck? Quantum corrections to the His mass have quadratic UV diverencies δm 2 H α π (Λ2 + m 2 F ) The cutoff Λ represents the scale up to which the Standard Model remains valid. need Λ of O(1 TeV) to avoid unnaturally lare corrections Most popular new physics models Supersymmetry Dynamical EWSB Extra dimensions Little His models Quantum corrections due to superparticles cancel the quadratic UV diverences δm 2 H α π (Λ2 + m 2 F ) δm 2 H α π (m2 F m2 F ) no fine-tunin if m < O(1 TeV) Michael Krämer Pae 2 Frontiers in QCD, September 2006

3 Introduction: Why Supersymmetrie? There are many ood reasons to study supersymmetric field theories and TeV-scale SUSY at colliders: SUSY is the unique extension of the Lorentz-symmetry SUSY provides a solution to the hierarchy problem SUSY allows for aue couplin unification SUSY provides a dark matter candidate SUSY can enerate EWSB dynamically... Michael Krämer Pae 3 Frontiers in QCD, September 2006

4 The Minimal Supersymmetric Standard Model The MSSM particle spectrum Gaue Bosons S = 1 Gauinos S = 1/2 luon, W ±, Z, γ luino, W, Z, γ Fermions S = 1/2 Sfermions S = 0 ( )( ul ν e ) L )( (ũl ν e ) L d L e L d L ẽ L u R, d R, e R His ( H 0 )( 2 H + 1 H2 H1 0 ) ( H 0 2 H 2 ũ R, d R, ẽ R Hisinos )( H + 1 H 0 1 ) Michael Krämer Pae 4 Frontiers in QCD, September 2006

5 Outline SUSY-particle production at the LHC MSSM His boson production at the LHC Michael Krämer Pae 5 Frontiers in QCD, September 2006

6 SUSY particle production at hadron colliders In the MSSM one imposes a symmetry to avoid proton decay SUSY particles produced pairwise R = ( 1) 3B+L+2S { = +1 SM = 1 SUSY lihtest SUSY particle stable (dark matter candidate) The interactions of MSSM particles are determined by aue symmetry and SUSY example: luon µ, a p, i no new couplin! q, j squark squark = i s (T a ) ij (p + q) µ SUSY particles should be produced copiously at hadron colliders throuh QCD processes, e.. Michael Krämer Pae 6 Frontiers in QCD, September 2006

7 Squark and luino cross section at the LHC σ tot Tevatron LHC σ (nb) σ bbar σ jet (E T jet > s/20) σ W σ Z σ jet (E T jet > 100 GeV) σ ttbar events/sec for L = cm -2 s -1 SUSY sinal: σ( q q + + q) 2 nb (M q, 300 GeV) 10 8 squarks & luinos/year ( L = 30 fb 1 ) 10-4 σ jet (E T jet > s/4) σ His (M H = 150 GeV) σ His (M H = 500 GeV) s (TeV) Michael Krämer Pae 7 Frontiers in QCD, September 2006

8 SUSY searches at hadron colliders Distinctive sinature due to cascade decays: multiple jets (and/or leptons) with lare amount of missin enery ~ ~ t q ~ ~ t 1 q ~ χ2 0 ~ l + q ~ χ 1 ~ χ 1 0 l - l + t W W + ν l + b q q b LHC discovery reach for squarks and luinos: M q, < 2.5 TeV Michael Krämer Pae 8 Frontiers in QCD, September 2006

9 Current limits on sparticle masses ) 2 Squark Mass (GeV/c DØ Run II Preliminary L=310 pb UA1 UA2 DØ IA LEP 1+2 CDF IB DØ IB DØ II 0 m(q ~ )<m( χ1 ) χ +/- LEP2 ~ LEP2 l no msugra solution Gluino Mass (GeV/c ) mass limits (rouhly) M M q M luino M t 1 M χ 0 1 > 200 GeV > 300 GeV > 100 GeV > 50 GeV ± M χ 1 > 100 GeV M sleptons > 100 GeV Michael Krämer Pae 9 Frontiers in QCD, September 2006

10 MSSM particle production at hadron colliders MSSM sparticle pair production squarks & luinos pp/p p q q,, q stops pp/p p t t auinos pp/p p χ 0 χ 0, χ ± χ 0, χ + χ sleptons pp/p p l l associated production pp/p p q χ, χ References of LO calculations: Kane, Leveillé, 1982; Harrison, Llewellyn Smith, 1983; Reya, Roy, 1985; Dawson, Eichten, Qui, 1985; Baer, Tata, 1985,... Michael Krämer Pae 10 Frontiers in QCD, September 2006

11 MSSM particle production at hadron colliders MSSM sparticle pair production squarks & luinos pp/p p q q,, q stops pp/p p t t auinos pp/p p χ 0 χ 0, χ ± χ 0, χ + χ sleptons pp/p p l l associated production pp/p p q χ, χ References of LO calculations: Kane, Leveillé, 1982; Harrison, Llewellyn Smith, 1983; Reya, Roy, 1985; Dawson, Eichten, Qui, 1985; Baer, Tata, 1985,... Michael Krämer Pae 11 Frontiers in QCD, September 2006

12 Top-squark production t L, t R mix to form mass states t 1, t 2 potentially small t 1 mass LO cross section q t 1 q t 1 ˆσ LO [q q+] = α2 sπ s [ ( ) ( β3 + β m2 2m s 3s ) ] + m4 lo 1 β 6s β (β 2 =1 4m 2 /s) no MSSM parameter dependence LO scale dependence σ(pp t 1t 1 +X) [pb] s=14 TeV; m(t 1) = 200 GeV LO 1 µ/m(t 1) theoretical uncertainty > 100% at LO must include NLO corrections Michael Krämer Pae 12 Frontiers in QCD, September 2006

13 SUSY-QCD corrections self eneries: + vertex corrections: + NLO cross section depends on squark & luino masses stop mixin anle dependence numerically small NLO cross section near threshold β 1: box diarams: + + σ q q α2 s (µ2 ) m 2 π 54 β3 ( 1 + 4πα s (µ 2 ) { 1 48β + 2 3π 2 ln2 (8β 2 ) π 2 ln(8β2 ) 2 3π 2 ln(8β2 ) ln ( µ 2 m 2 ) }) luon emission: + luon-quark scatterin: + σ α2 s (µ2 ) m 2 7π 384 β ( 1 + 4πα s (µ 2 ) { β + 3 2π 2 ln2 (8β 2 ) π 2 ln(8β2 ) 2 3π 2 ln(8β2 ) ln ( µ 2 m 2 )}) lare NLO corrections in channel Michael Krämer Pae 13 Frontiers in QCD, September 2006

14 SUSY-QCD corrections: results reduced scale dependence < 15% K-faktor K = σ(nlo)/σ(lo) (Beenakker, MK, Plehn, Spira, Zerwas) 1.7 (Beenakker, MK, Plehn, Spira, Zerwas) LO σ(pp t 1t 1 +X) [pb] s=2 TeV; m(t 1) = 200 GeV pp/pp t 1t 1 +X K = σ(nlo)/σ(lo) LHC NLO Tevatron ( s=2 TeV) µ/m(t 1) m(t 1) Michael Krämer Pae 14 Frontiers in QCD, September 2006

15 Top-squark searches Top-squark search in e ± e ± + 2j final startes (CDF, Phys. Rev. Lett. 83 (1999)) σ(pp t 1t 1 + X) BR(t 1 t 1 ee + 2j) [pb] 1 σ NLO : µ=[m(t )/2, 2m(t )] σ LO : µ=[m(t )/2, 2m(t )] CDF 95% C.L. upper limit (prel.) m(χ o )=m(t 1)/2 1 M LO M NLO m(t 1) [GeV] M t1 > 110 ± 15 GeV LO 120 ± 5 GeV NLO Michael Krämer Pae 15 Frontiers in QCD, September 2006

16 Current project: associated pp/p p q χ, χ production semi-weak process, but χs are liht in most models q χ pp/p p χ q q Beenakker, MK, Plehn, Spira, Zerwas; Berer, Klasen, Tait q χ pp/p p qχ q q LO scale uncertainty O(100%) need NLO calculation Michael Krämer Pae 16 Frontiers in QCD, September 2006

17 SUSY-QCD corrections + SUSY breakin in dimensional reularization, χ: 2 d.o.f., γ, Z: (n 2) d.o.f. + restauration throuh finite counter terms q q χ q + double countin: q q q χ q (if m q > m χ ) dσ res dm 2 = σ( q q) m q Γ q /π (M 2 m 2 q )2 + m2 q Γ2 q BR( q χ q) χ σ( q q)br( q χ q)δ(m 2 m 2 q ) q q + resonance contributions to be subtracted q Michael Krämer Pae 17 Frontiers in QCD, September 2006

18 SUSY-QCD corrections: preliminary results reduced scale dependence Tevatron LHC 0.08 Beenakker, MK, Plehn, Spira, Zerwas 0.5 Beenakker, MK, Plehn, Spira, Zerwas preliminary σ(pp _ q ~ χ 2 +X)[pb] s = 1.96 TeV CTEQ5M preliminary σ(pp q ~ χ 2 +X)[pb] s = 14 TeV CTEQ5M NLO 0.03 NLO LO 0.15 LO Q/m Q/m Michael Krämer Pae 18 Frontiers in QCD, September 2006

19 MSSM particle production at the LHC NLO SUSY-QCD corrections for MSSM particle production at hadron colliders public code PROSPINO (Beenakker, MK, Plehn, Spira, Zerwas) χ o + 2 χ 1 σ tot [pb]: pp, q q, t 1t 1, χ 2 o χ + 1, ν ν, χ o 2, χ o 2 q ν ν t 1t 1 χ 2o q χ o q q S = 14 TeV NLO LO m [GeV] References: Beenakker, Höpker, Spira, Zerwas, 1995, 1997; Beenakker, MK, Plehn, Spira, Zerwas, 1998; Baer, Hall, Reno, 1998; Beenakker, Klasen, MK, Plehn, Spira, Zerwas, 1999; Beenakker, MK, Plehn, Spira, Zerwas, 2000; Berer, Klasen, Tait, ; Beenakker, MK, Plehn, Spira, Zerwas, 2006 Michael Krämer Pae 19 Frontiers in QCD, September 2006

20 SUSY with R-Parity violation SUSY models without R-parity allow for resonant sinle sparticle production Example: resonant slepton production: L = λ ijk ( drk d Lj ν Li d Rk u Lj lli ) q S σ LO = λ 2 π 12s δ(1 τ) with τ = M 2 s q NLO (SUSY-)QCD corrections sizeable (Dreiner, Grab, MK, Trenkel 2006) SPS 1a SPS 2 SPS K-Factor K-Factor K-Factor QCD QCD + SUSY (A = 0TeV ) QCD + SUSY (A = 1TeV QCD + SUSY (A = -1TeV) 1.2 QCD QCD + SUSY (A = 0TeV) QCD +SUSY (A = 1TeV) QCD + SUSY (A = -1TeV) 1.2 QCD QCD + SUSY (A = 0TeV) QCD + SUSY (A = 1TeV) QCD + SUSY (A = -1TeV) [TeV] m ν ~ [TeV] m ν ~ (TeV) m ν ~ Michael Krämer Pae 20 Frontiers in QCD, September 2006

21 SUSY Searches Hans-Peter Nilles, Physics Reports 110, 1984: Experiments within the next 5-10 years will enable us to decide whether supersymmetry, as a solution of the naturalness problem of the weak interaction is a myth or reality Hans-Peter Nilles, private communication, quoted from hep-ex/ One should not ive up yet... Perhaps a correct statement is: it will always take 5-10 years to discover SUSY. Michael Krämer Pae 21 Frontiers in QCD, September 2006

22 A crucial test of the MSSM: the liht His MSSM His sector: two His doublets to ive mass to up- and down-quarks 5 physical states: h, H, A, H ± The MSSM His sector is determined by tan β = v 2 /v 1 and M A. The couplins in the His potential and the aue couplins are related by supersymmetry. At tree level one finds M h M Z. This relation is modified by radiative corrections so that M H < 130 GeV (in the MSSM) The existence of a liht His boson is a eneric prediction of SUSY models. Michael Krämer Pae 22 Frontiers in QCD, September 2006

23 A crucial test of the MSSM: the liht His One of the SUSY His bosons will be seen at the LHC tanβ h 0 H A H ATLAS ATLAS fb maximal mixin 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 but it may look like the SM His... m A (GeV) Michael Krämer Pae 23 Frontiers in QCD, September 2006

24 His production in the MSSM His production in the SM throuh top-quark loops t H tth production t H t m 2 top dps(t th) Michael Krämer Pae 24 Frontiers in QCD, September 2006

25 His production in the MSSM His production in the MSSM throuh t, b-quark loops + squark loops t, b H + t H tth production and bbh production t b H H t b m 2 top dps(t th) m 2 b tan β dps(b bh) Michael Krämer Pae 25 Frontiers in QCD, September 2006

26 His production in the MSSM Cross section predictions: liht and heavy scalar h and H [Spira] Cross-section (pb) h H Hbb tan β = 30 Maximal mixin H (SM) Hqq H 10-2 Htt HZ HW m h/h (GeV) Michael Krämer Pae 26 Frontiers in QCD, September 2006

27 His production in the MSSM: luophobic His t, b H + t H interference effects Gluophobic His scenario [Djouadi; Carena et al.; Harlander, Steinhauser; Mühlleitner, Spira] σ(pp h+x) [pb] LHC [Harlander, Steinhauser] SUSY, NNLO SUSY, NLO SUSY, LO SM, NNLO SM, NLO SM, LO m ~ t [GeV] 2 MSSM parameters m t 1 = 200 GeV m = 1 TeV tan β = 10 α = 0 θ t = π/4 Michael Krämer Pae 27 Frontiers in QCD, September 2006

28 His production in the MSSM: associated b bh production Associated Q Q-His production P P Q φ Q is crucial as a His discovery channel to measure the heavy-quark His Yukawa couplins 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, e.: MSSM bbh = sin α cos β SM bbh tan β 1 tan β SM bbh (M h M A M Z ) Michael Krämer Pae 28 Frontiers in QCD, September 2006

29 QQH production mechanism At leadin order }{{}}{{}}{{} M Q M H : α 2 s ln 2 (M H /M Q ) α 2 s ln(m H /M Q ) α 2 s Summation of ln(m H /M Q ) terms by usin heavy quark PDFs [Collins, Olness, Tun; Barnett, Haber, Soper; Dicus, Willenbrock,... ] M Q M H Michael Krämer Pae 29 Frontiers in QCD, September 2006

30 Inclusive b bh production: two calculational schemes 4-flavour scheme 5-flavour scheme + exact b b splittin & mass effects no summation of ln(m H /M b ) terms + summation of ln(m H /M b ) terms LL approximation to b b splittin Comparison at LO stron scale dependence σ(b b H) σ( b bh) at µ = M H discrepancy reduced at µ F = M H /4 [Spira; Maltoni, Sullivan, Willenbrock; Boos, Plehn] Choice of scale? Impact of HO corrections? comparison at the NLO/NNLO level Michael Krämer Pae 30 Frontiers in QCD, September 2006

31 NLO corrections to 4-flavour scheme: b bh Q Q NLO Feynman raphs: H H + Q Q Beenakker, Dittmaier, MK, Plümper, Spira, Zerwas; Dawson, Jackson, Orr, Reina, Wackeroth 4-flavour scheme: scale dependence at the LHC (SM His): tot [Dittmaier, MK, Spira] σ(pp bb _ H + X) [fb] s = 14 TeV M H = 120 GeV µ 0 = m b + M H /2 NLO 200 LO _ p Tb and p Tb > 20 GeV NLO 20 LO µ/µ 0 Michael Krämer Pae 31 Frontiers in QCD, September 2006

32 NNLO corrections to 5-flavour scheme: b b h Renormalization and factorization scale dependence [Harlander, Kilore] σ(pp (bb )H+X) [pb] LHC M H =120 GeV σ(pp (bb )H+X) [pb] LHC M H =120 GeV LO NLO 0.2 NNLO µ F = M H / µ R /M H 0.4 LO NLO 0.2 NNLO µ R =M H µ F /M H Michael Krämer Pae 32 Frontiers in QCD, September 2006

33 Inclusive His plus bottom-quark production Comparison of 4- and 5-flavour schemes at (N)NLO (SM His, LHC) [Harlander, Kilore; Dittmaier, MK, Spira] 10 3 σ(pp bb _ h + X) [fb] s = 14 TeV µ = (2m b + M h )/ bb _ h (NNLO) 10 bb _ h (NLO) M h [GeV] 4-flavour calculation includes His radiation off top loops 10% calculations employ different PDF fits consistent comparison should reveal even better areement Michael Krämer Pae 33 Frontiers in QCD, September 2006

34 Associated Heavy Quark His Production: Status h/h + Q Q: QCD corrections, full SUSY-QCD in proress [Pen, Wen-Gan, Hon-Shen, Ren-You, Lian, Yi; Dittmaier, Häflier, MK, Spira, in preparation] A + Q Q: QCD corrections [Dittmaier, MK, Spira, preliminary] H ± + Q Q : (SUSY)-QCD corrections [Pen, Wen-Gan, Ren-You, Yi, Lian, Lei; Dittmaier, Spira, MK, Walcher, in preparation] b b h/h/a: NNLO QCD corrections [Harlander, Kilore] MSSM EW corrections [Dittmaier, MK, Mück, in preparation] b h/h/a + b, b H ± + t: NLO (SUSY-)QCD corrections [Plehn; Zhu; Campbell, Ellis, Maltoni, Willenbrock; Berer, Han, Jian, Plehn; Alves, Plehn,... ] Lots of activity and onoin calculations... Michael Krämer Pae 34 Frontiers in QCD, September 2006

35 Summary Production cross sections (and decay rates) for MSSM SUSY particles and His bosons are (or will soon be) known at NLO (SUSY-)QCD theoretical uncertainty reduced to 15% But still lots of work to be done... only few results exist for other SUSY models (e.. RPV SUSY) electroweak corrections are only partially known many backrounds (multi-parton processes) are only know at LO Michael Krämer Pae 35 Frontiers in QCD, September 2006