Higgs and SUSY at future colliders Yasuhiro Okada (KEK) Hiroshima Univ. January 17, 2006

Why TeV?, Why New Physics? LHC will start in the next year, which will explore TeV scale physics. Main objectives are Higgs physics and search for New physics. These two are closely related because the dynamics behind the electroweak symmetry breaking is “New Physics”.

Other reasons to believe physics beyond the Standard Model Neutrino masses Dark Matter Baryon number in the Universe. Solutions to these questions may or may not lie in the TeV region.

Contents of this talk (1) Higgs Physics (2) Supersymmetry (3) Dark Matter and collider physics.

(1) Higgs Physics Finding the mass-generation mechanism for gauge bosons, quarks and leptons the most urgent question of the present particle physics. Discovery of the Higgs boson is the first step (1) Discovery of a Higgs boson (2) Higgs coupling measurements. (3) Physics behind the EW symmetry breaking

Higgs mass Large Higgs mass  Large self-coupling  Strong dynamics If we require that the SM is valid up to 10^19 GeV,

Higgs mass in SUSY models SUSY models include at least two Higgs doublets. In the minimal SUSY Standard Model (MSSM), the lightest CP-even Higgs boson mass has theoretical upper bound. Possible vacuum instability is saved by supersymmetry.

Possible range of the lightest Higgs boson mass for the Planck scale cutoff As long as theory behaves weakly-coupled up to the Planck scale, the Higgs bosom mass is les than ~200 geV.

Precision EW test and the Higgs Mass In the SM, the global fit suggests a light Higgs boson. M.Peskin and J.Wells mt=174.3+-5.1GeV mh=100,200,300,500,1000 GeV Additional new physics is needed to accommodate a heavy Higgs boson.

Higgs search at LHC LHC： 2007 14 TeV pp collider Discovery of the Higgs boson is a main target. Higgs boson search depends on the Higgs boson mass Production:　gluon fusion, WW fusion Decay: decay to heavier particles if kinematically allowed. p p Ｗ gluon Higgs boson Higgs boson Ｗ p gluon p

SM Higgs boson decay branching ratios Higgs discovery at ATLAS At LHC, a SM-like Higgs boson can be discovered independent of its mass.

ILC (International Linear Collider) Highest energy e^+e^- collider 　　500 GeV (1st stage) -> ~ 1 TeV (2nd stage) High luminosity, 10^34/cm^2/s　 　　　(~10^5 light Higgs boson =Higgs factory Startin mid-2010’s　

Higgs physics at ILC Determination of spin and parity. Precise mass determination . Detection of the Higgs boson independent of its decay property. (Recoil mass distribution in the HZ mode) Coupling measurement -> Mass generation mechanism of elementary particles. TESLA TDR GLC report

Higgs coupling LHC 0(10)% for ratio of the coupling constants ILC A few % for absolute values of various coupling

Indirect constraint on the heavy Higgs boson mass in MSSM Direct search at LHC Direct search at 1TeV LC ACFA Higgs WG S. Kiyoura, et al ACFA report

SUSY loop contributions to the hbb Yukawa coupling B(h->bb)/B(h->tt) is sensitive to the SUSY loop correction to the bottom Yukawa coupling for a large tanb region. B(h->bb)/B(h->tt) nomalized by SM value LC LHC K.S.Babu, C.Kolda: M.Carena, D.Garcia, U.Nierste, C.E.M.Wagner J.Guasch, W.Hollik,S.Penaranda

Higgs self-coupling measurement Access to the Higgs potential. Precision at 1/ab for 120 GeV Higgs boson ~20% for 500GeV ILC ~10% for 1 TeV ILC Y.Yasui, et al, LCWS 02

Electroweak baryogenesis and Higgs potential First order phase transition Extension of the Higgs sector The Higgs potential at zero temperature is also modified. => Self coupling measurement Model with dim 6 potential 2HDM S.Kaenmura, Y. Okada, E.Senaha C.Grojean,G.Servant, J.D.Wells

Higgs and physics beyond the SM Even if one Higgs doublet model is a good description, What is f? What physics determines –m^2? What physics determines l? Different scenarios provides different answers. SUSY, String Theory Composite model, Little Higgs model TeV scale extra dimension

Composite model ~10 TeV a SUSY GUT Gravity Gauge force Extra dimension Various new physics signals are expected in the TeV region, depending on different signals.

(2) Supersymmetry Symmetry between bosons and fermions Discovery of SUSY is a revolution of physics similar to relativity. (extension of relativity, generalization of the space-time concept) A solution to the hierarchy problem. The coupling unification in SUSY GUT

Hierarchy problem and SUSY String and GUT unification -> A cutoff scale ~ Planck scale (10^19 GeV). SUSY is the only known symmetry to avoid the fine tuning in the renormalization of the Higgs boson mass at the level of O(10^34). Three possibilities: Some new dynamics associated with the electroweak symmetry breaking exists just above the TeV scale. SUSY exists. Fine-tuning is realized by unknown reason. => LHC will provide a hint on which is the correct direction.

SUSY models A SUSY model is not a single model, rather collection of models. The number of free parameters of the minimal supersymmetric standard model (MSSM) is about 100. Low energy SUSY models = SUSY extensions of the SM R-parity conserving model R-parity violation MSSM NMSSM, Extra U(1), etc. SUSY Breaking scenarios (mSUGRA, AMSB, GMSB, etc.) SUSY GUT, See-saw neutrino, String unification No strong motivations to consider beyond the MSSM.

MSSM The particle content of MSSM = Two Higgs doublet SM + scalar SUSY partners and fermionic SUSY partners Two Higgs doublets are necessary for fermion Yukawa couplings. H1: down-type-quark and lepton Yukawa couplings H2: up-type-quark Yukawa couplings

ＳＵＳＹ phenomenology Discover SUSY particles Establish the symmetry property. Determine SUSY breaking mechanism. Clarify the meaning in unification and the cosmological connection.

SUSY at LHC LHC experiments will provide a crucial test for SUSY. Mass reach of squark and gluino search is about 2 TeV. A light Higgs boson below 135 GeV must exist for MSSM. Higgs search: At least one Higgs boson can be found. SUSY search: Cascade decay. ~gluino 2 TeV m1/2(GeV) mSUGRA MSSM

LC studies on SUSY Determine mass, spin and quantum numbers of SUSY particles. Beam polarization and energy scan are very useful tools. Determine chargino and neutralino mixings. Test SUSY coupling relations. Test the gaugino GUT relation. Determine properties of the dark matter candidate. Search for lepton flavor violation in slepton production and decays.

Smuon production and decay Test of a SUSY relation Smuon production and decay　 Selectron production Dark matter candidate? M.M.Nojiri, K. Fujii and T. Tsukamoto

SUSY breaking scenario Combined analysis of LHC and LC provide a hint on a SUSY breaking scenario. LHC: Squark and gluino production and cascade decay LC: Slepton, neutlarino, and chargino pair-production SUSY particle masses Combined analysis Energy scale SUSY breaking scenario G.A.Blair, W.Porod,and P.M.Zerwas

SUSY Seesaw model Large Lepton flavor violation processes are expected. m->eg in SU(5) SUSY GUT with seesaw neutrino Slepton flavor mixing J.Hisano, M.M.Nojiri, Y.Shimizu, M.Tanaka MEG experiment T.Goto,Y.Shimizu,T.Shindo,M.Tanaka and Y.Okada.

(3) Dark matter and collider physics Energy composition of the Universe Dark energy 73% 　 Dark matter 23% 　 Baryon　　　　　4% Dark matter candidate WINP （weakly interacting massive particle) 　Stable, neutral

Relic abundance of dark matter A larger pair annihilation cross section -> Smaller relic abundance Candidates of dark matter 　 SUSY neutralino, gravitino 　 KK-photon in the universal extra dimension model, Heavy photon in the little Higgs model with a T parity Collider physics (1) Discovery of the dark matter candidate (2) Identify a correct model. (3) Determine the mass and couplings and compare the relic abundance.

Identification of the dark matter at LC 　Even if a dark matter candidate is found at LHC by missing energy signals, many possibilities can exist. Ex. SUSY and KK model can be distinguished at LC. Threshold behaviors for smuon and KK muon productions neutralino sneutrino KK photon M.Peskin

SUSY Dark matter at LC SUSY mass and coupling measurements ALCPG cosmology subgroup SUSY mass and coupling measurements => Identification of dark matter PLANCK WMAP

Conclusions Discovery of the Higgs boson is the first step to understand the dynamics of the electroweak symmetry breaking. In order to confirm the mass generation mechanism of elementary particles, coupling constants related to the Higgs boson have to be measured precisely. SUSY, if it exists, has far-reaching consequences in particle physics and cosmology.