Martin zur Nedden, HU Berlin 1 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Physics at the LHC Academic Training, Part 4: Higgs Search and Beyond Standard Model Dr. Sven Moch, DESY Zeuthen (Theory) Dr. Martin zur Nedden, HU Berlin (Experiment) June 2007 DESY Zeuthen, based on a lecture in WS 06/07 at Humboldt University Berlin

Martin zur Nedden, HU Berlin 2 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Plan LHC: Experimental Overview and Standard Model Physics (Part 3) – Monday, June 11, 2007, LHC: Higgs Searches and Physics beyon the Standard Model (Part 4) – Thursday, June 14, 2007, – 11.30

Martin zur Nedden, HU Berlin 3 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Contents Discoveries at the energy frontier Overview: LHC and its experiments Hadron-Hadron interactions Jets: fragmentation, signature and algorithms Standard model channels at LHC top-physics and heavy flavor reconstruction Higgs: event topologies and search strategies SUSY: searches in the MSSM

Martin zur Nedden, HU Berlin 4 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Higgs Searches Yukava-coupling, masses of fermions experimental evidence: – production – decays and search channels results from TEVATRON searches at LHC

Martin zur Nedden, HU Berlin 5 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Higgs Mechanism in the Standard Model Doublet Φ of scalar Higgs fields H(x) exists due to the massive gauge field W,Z and the massless γ Complex fields Φ +, Φ 0 4 real components Φ 1, …Φ 4, produce mass in symmetry breaking due to self- interaction Goldstone/Higgs-mechanism: 3 components absorbed in the longitudinal polarization of the massive 3 W i -bosons 1 physical state H remains coupling to mass with g ffH No prediction of Higgs mass by SM

Martin zur Nedden, HU Berlin 6 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Yukava coupling, Mass of Fermions new term in Lagrangien needed: excluded due to gauge invariance e R (T=0, Y=-2) e L (T=1/2, Y=-1) h 0 (T=1/2, Y=1) igm e /(2M W ) igM W W W (Singlet in I,Y) choose: Coupling to the higgs field h0h0

Martin zur Nedden, HU Berlin 7 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Consequences from Yukava-Coupling electron gets mass neutrino rest massles strength of coupling proportional to the mass of the fermion mass is not predicted by the theory masses for quarks: – same formalism as for leptons – difference: both quarks within the doublet have mass new Higgs Doublet Φ c

Martin zur Nedden, HU Berlin 8 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Higgs-Production in Hadron-Hadron Interactions gluon-gluon interaction (LHC/TEVATRON): big production cross section, decay in 2 gammas gluon-gluon interaction (LHC/TEVATRON): production cross section very small quark-antiquark interaction (TEVATRON): big production cross section at 2TeV (TEVATRON) decay: W,Z leptons quark-quark interaction (LHC): big production cross section at 14TeV (LHC) decay: W,Z 2 γ (or leptons)

Martin zur Nedden, HU Berlin 9 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Decay Width of Different Higgs Channesl Calculations in the standard model:

Martin zur Nedden, HU Berlin 10 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Higgs – Decay Channels (H VV) ~ G F M 3 H (H γγ) ~ α 2 G F M 3 H (H ff) ~ G F m 2 f M H

Martin zur Nedden, HU Berlin 11 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Possible Higgs Decays / coupling constants

Martin zur Nedden, HU Berlin 12 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Higgs Search Strategies Good channel for TEVATRON: M(H) > 135 GeV: H WW M(H) < 135 GeV: H bb gg-fusion dominant at all Higgs masses, not to separate from BG at M < 135 GeV qq: Higgs-Strahlung: small contribution, but god to separate from BG

Martin zur Nedden, HU Berlin 13 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Cross Sections at TEVATRON

Martin zur Nedden, HU Berlin 14 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Higgs Search at TEVATRON, upper Limit signal: 2 b-Jet + MET + 2 leptons if M(H) > 135 GeV

Martin zur Nedden, HU Berlin 15 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Upper Limit for Higgs production at TEVATRON if M(H) < 135 GeV

Martin zur Nedden, HU Berlin 16 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Higgs Decay Channels: Branching Ratios

Martin zur Nedden, HU Berlin 17 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Higgs Decay in the Standard Modell fermions bosons decay width branching ratio

Martin zur Nedden, HU Berlin 18 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Higgs Cross Sections at LHC gluon-gluon fusion vector boson fusion

Martin zur Nedden, HU Berlin 19 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Higgs: Signal to background ratio at LHC for M(Higgs) = 150 GeV: S/B <

Martin zur Nedden, HU Berlin 20 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Higgs to 2 Z and 4 Leptons CMS TDR Very clean an good measurabe event signature: 4 high p T leptons, 2 invariant masses at M Z

Martin zur Nedden, HU Berlin 21 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Gluon-Gluon Fusion to 4 Leptonen (Atlas/LHC) Atlas TDR invariant masse (ZZ 4 l) Background, not to distinguish from Higgs-Signal: qq ZZ 4 leptons

Martin zur Nedden, HU Berlin 22 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Higgs to 2 Gamma CMS also very clean signature, but small cross section: 2 high p T isolated EMC-clusters

Martin zur Nedden, HU Berlin 23 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Gluon/Gluon Fusion to 2 Gamma (Atlas/LHC) ATLAS TDR Background: Not reducable: pp γγX Reducable: pp γJγJ

Martin zur Nedden, HU Berlin 24 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Vektor-Boson Fusion: Decay to 2 W-Bosons H WW e Atlas TDR H WW l l υ υ (l υ qq ) Signature: Jets + 2 high p T leptons + MET No mass peak (MET from neutrino), calculate the transverse mass Background: tt, Wt, WWJJ production

Martin zur Nedden, HU Berlin 25 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Higgs to 2 Tau H ττ e : H ττ l l + 4ν (l +J +3ν) Atlas TDR 2 high p T leptons, big MET Mass reconstruction possible, even with high MET Background: Zjj, tt

Martin zur Nedden, HU Berlin 26 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Higgs Discovery potential of LHC/ATLAS Dependency on Higgs mass and decay channel

Martin zur Nedden, HU Berlin 27 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Discovery potential of ATLAS/LHC Dependency of Higgs-mass and Luminosity

Martin zur Nedden, HU Berlin 28 Physics at the LHC, Academic Training DESY Zeuthen June 2007 SUper SYmmetry Beyond the Standart Model introduction into SUper SYmmetry Minimal Super Symmetric extension of the standard Model (MSSM) super symmetric interactions SUSY breaking particle spectra of SUSY (phenomenology) SUSY searches

Martin zur Nedden, HU Berlin 29 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Global Fit of Standard Model Parameter

Martin zur Nedden, HU Berlin 30 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Weinberg Angle and Higgs-Masse

Martin zur Nedden, HU Berlin 31 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Standard Model Symmetry SM describes strong and electroweak interactions, L/R asymmetry Based on symmetries and gauge invariance All forces propagated by exchange of gauge fields (local gauge fields) Gauge-Bosons (Spin = 1): gluons G a μ SU(3) (8,1,0) vector bosons W i μ SU(2) (1,3,0) abelian boson B μ U(1) (1,1,0) Fermions Spin = ½: quarks [U i α,D i α ] L (3,2,1/3) quarks [U i α ] R (3,1,4/3) quarks [D i α ] R (3,1,-2/3) leptons [L α ] L (1,2,-1) leptons [e] R (1,1,-2) Higgs (Spin = 0): H-Doublet [H 0,H - ] (1,2,-1) Masses of quarks, leptons and vectorbosons by spontanous symmetry breaking

Martin zur Nedden, HU Berlin 32 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Motivation for Super Symmetry Fermion Boson Symmetry basic idea: unification of all forces, no difference between fermions (matter) and bosons (forces) generator of the SUSY algebra: Q|boson> = |fermion> Q|fermion> = |boson> Difference in spin = ½, doubling of the number of particles SUSY transformation: δ|b> = ε|f> (anti-) kommutator relations {f,f} =0, [b,b] = 0, {ε,ε} = 0 : SUSY generators are fermionic Q has spin = ½, may change the helicity 2-component spinor super symmetric algebra: connection of particles with different spins

Martin zur Nedden, HU Berlin 33 Physics at the LHC, Academic Training DESY Zeuthen June 2007 electron selectron quark squark photon photino Unification of bosons with fermions forces with matter fermiosbosonsbosonsfermions Super symmetric Partners

Martin zur Nedden, HU Berlin 34 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Minimal Super Symmetric Model (MSSM) Most simple case: N=1 generators 2 super multiplets: NDoF (bosons) = NDoF(fermions) 1. chiral super multiplet [Φ, Ψ] (spin 0, ½), fermions: 2 scalars, Weyl-spinor with helicity, L/R 2. vector multiplet [λ, A] (spin ½, 1), bosons: gauge boson, massless spin ½ fermion each fundamental particle has to occur in a super multiplet each SM particle has a SUSY-partner, Δs = ½ (minimal number of new particles) fermions in the vector multiplet transforms like gauge bosons (same for L/R) chiral multiplet contains all fermions, also with different transformation behaviour unbroken super symmetry: all masses were the same obviously not the case…… SUSY must be (weakly) broken, big masses of super symmetric partners More than 100 new parameters for the theory !?

Martin zur Nedden, HU Berlin 35 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Extended Higgs Model in MSSM 2 Higgs Dublets needed, to give all particles mass Complex fields 8 degrees of freedom 3 absorbed in the longitudinal components of W- and Z-bosons 5 higgs bosons remains, 3 are neutral h 0 : light Higgs, scalar H 0 : heavy Higgs, scalar A 0 : neutral Higgs, pseudo-scalar, PC-odd H + /H - : charged Higgs, scalar h 0 /H 0 mixing states of Re(H u 0 ) and Re(H d 0 ), Mixing angle α A 0 mixing state of Re(H u 0 ) and Re(H d 0 ), Mixing angle tanβ H + /H - mixing state of H u + and H d -, Mixing angle tanβ new parameter For the masses follows:

Martin zur Nedden, HU Berlin 36 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Higgs Masses in MSSM Higgs masses depends on 2 parameters: tan β and m A : – tan β 1 : m h = 0, m H 2 = M Z 2 + m A 2 – tan β : m h = min(M Z, m A ), m H = max(M Z,m A ) – Mass terms for A 0, H 0 and H + /H - could be very big! – If m A big: m A ~ m H ~ m H +/- – Mass of h 0 is limited: 0 < m h < |cos2β|M Z m h < m A < m H m H > M Z, m H +/- > M W – Radiative corrections important for mh (enlarges the mass) – m h 0 < 150 GeV upper limit for MSSM – m h 0 < 190 GeV limit for SUSY

Martin zur Nedden, HU Berlin 37 Physics at the LHC, Academic Training DESY Zeuthen June 2007 MSSM Higgs Masses All Higgs masses are fixed relative to 2 parameters:

Martin zur Nedden, HU Berlin 38 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Cancelation of Quantum corrections in SUSY Models

Martin zur Nedden, HU Berlin 39 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Supersymmetric Particles Chargino : (partner of W) Neutralino : (partner of Z, g) Smuon : (partner of muon)

Martin zur Nedden, HU Berlin 40 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Super Partners q L, q R, l L, l R squarks, sleptons (spin = 0) Gauge bosons g, W, B (gluino, Wino, Bino) = gauginos SM: coupling of W 0 /B 0 to Z 0 /γ Zino, Photino Higgs (scalar) 2 Higgsinos (chiral super multiplet) chiral super multiplet: left handed particles only gauge interaction the same for squarks/sleptons and quarks/leptons unification with gravity: Graviton Gravitino neutral fermionic partners Wino/Bino have the same quantum numbers as the super symmetric Higgs partners: mixing to 4 neutralinos χ 0 i (i=1..4) : the lightest neutralino is the LSP (if R-parity is conserved) charged Higgsinos: mixing to charginos χ +/- j, (j=1,2)

Martin zur Nedden, HU Berlin 41 Physics at the LHC, Academic Training DESY Zeuthen June 2007 SUSY Interactions (R-Parity conserved) R-parity: +1 for normal particles, -1 for super symmetric partners Feynman graphs: replace at any SM-vertex (3 or 4 particle interaction) two legs by the corresponding super symmetric partners The coupling constants remains the same as in SM (strong or electroweak)

Martin zur Nedden, HU Berlin 42 Physics at the LHC, Academic Training DESY Zeuthen June 2007 MSUGRA - Parameters m 0 : universal scalar mass at GUT scale m ½ : universal gaugino mass at GUT scale tan β : ratio of Higgs vacuum expectation value A 0 : universal s-fermion mass mixing parameter sgn μ: sing of Higgsino mass parameter M(SUSY) < 1 TeV for LSP important limits from LEP and TEVATRON

Martin zur Nedden, HU Berlin 43 Physics at the LHC, Academic Training DESY Zeuthen June 2007 MSUGRA Masses

Martin zur Nedden, HU Berlin 44 Physics at the LHC, Academic Training DESY Zeuthen June 2007 MSUGA Szenarios 1

Martin zur Nedden, HU Berlin 45 Physics at the LHC, Academic Training DESY Zeuthen June 2007 MSUGRA Szenarios 2

Martin zur Nedden, HU Berlin 46 Physics at the LHC, Academic Training DESY Zeuthen June 2007 SUSY at Hadron-Colliders search strategy: Big contribution from standard model QCD-background (Jets) look for high p T leptons and MET - squarks and gluinos : MET (strong interaction) - neutralinos and charginos : MET and high pT leptons (electro weak interaction)

Martin zur Nedden, HU Berlin 47 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Squark und Gluino Searches at TEVATRON production: decay: Search for Jets und E T miss

Martin zur Nedden, HU Berlin 48 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Result: Upper Limits (exclusions limits)

Martin zur Nedden, HU Berlin 49 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Search for Neutralinos and Charginos No improved SUSY limit found by TEVATRON up to now

Martin zur Nedden, HU Berlin 50 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Recostruction of SUSY Particles Neutralino 2 Sbottom Gluino CMS MC analysis M = 595 GeV M = 510 GeV M = 174 GeV M = 150 GeV M = 96 GeV edge = /- 2.1 GeVM = /- 6.6 GeV M = / GeV

Martin zur Nedden, HU Berlin 51 Physics at the LHC, Academic Training DESY Zeuthen June 2007 SUSY in R-Parity violating Processes neutralino (LSP) unstable, no longer a dark matter candidate lepton / and baryon number conservation violated much more possible decay channels …. L - violation B - violation L - violation

Martin zur Nedden, HU Berlin 52 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Neutralino in R-Parity violating Decays production: decay: Evidence: 3 charged leptons in FS

Martin zur Nedden, HU Berlin 53 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Search at Tevatron (Neutralino decay) production: decay: Evidence: 3 charged leptons in FS Result from D0, TEVATRON: upper limit

Martin zur Nedden, HU Berlin 54 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Masse of the lightest MSSM-Higgs Mass of the lightest Higgs as a function of M A und tan(ß) from 1.6 to 15

Martin zur Nedden, HU Berlin 55 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Supersymmetric Higgs

Martin zur Nedden, HU Berlin 56 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Search for the neutral MSSM Higgs Searches at TEVATON: using multi – jet events

Martin zur Nedden, HU Berlin 57 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Di-Jet Mass (D0 / Tevatron) MSSM Higgs Search for overshoot in the invariant mass distribution of the two jets with the highest p T At least 3 b-flavoured jet are requested per event BG: multi jet production

Martin zur Nedden, HU Berlin 58 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Upper Limit for the MSSM-Higgs Mass based on di-Jet events

Martin zur Nedden, HU Berlin 59 Physics at the LHC, Academic Training DESY Zeuthen June 2007 Search for the MSSM charged Higgs Search for MET + J + X: Direct production in weak IA, compeditiv to t Wb

Martin zur Nedden, HU Berlin 60 Physics at the LHC, Academic Training DESY Zeuthen June 2007 MSSM – Higgs Search at LHC All region is coverd…

Martin zur Nedden, HU Berlin 61 Physics at the LHC, Academic Training DESY Zeuthen June 2007 SUSY Mass Spectra