Significant effects of second KK particles on LKP dark matter physics Collaborated with Mitsuru Kakizaki (ICRR) Mitsuru Kakizaki (ICRR) Shigeki Matsumoto (ICRR) Shigeki Matsumoto (ICRR) Yoshio Sato (Saitama U.) Yoshio Sato (Saitama U.) hep-ph/ Masato Senami (ICRR, University of Tokyo) Kaluza-Klein dark matter WMAP result establish the existence of non-baryonic cold dark matter Weakly Interacting Massive Particle (WIMP) is excellent candidate Lightest supersymmetric particle Lightest Kaluza-Klein particle (LKP) in universal extra dimension (UED) models Universal Extra Dimension model Universal means all SM particles propagate in spatial extra dimensions Momentum conservation in higher dim. = KK number conservation KK parity conservation To obtain chiral fermion at zero mode, the extra dimension is compactified by S 1 /Z 2 LKP is stable Mass spectrum In 4 dim. viewpoint LKP is a good candidate of DM Eq. of motion 1/R=500 GeV, R=20, m h =120 GeV Mass of KK particle Each KK mode has degenerate mass Radiative corrections remove the degeneracy Lightest KK particle Mass spectrum Cheng, Matchev and Schmaltz (SM massless particles are exactly degenerate) m = mass of LKP Dark matter relic abundance After annihilation rate dropped below the Hubble parameter, LKP can not annihilate and the density per comoving volume is fixed. Large cross section small relic abundance Servant and Tait Tree level annihilation diagrams DM relic abundance Large mass of DM particle They consider only the first KK modes Second KK s-channel Since DM is non-relativistic, the incident energy of two LKPs is almost degenerate with the mass of second KK modes In particular, s-channel LKP annihilation process mediated by competes with tree level diagrams because of the resonance does not couple with SM particle at tree level One of the resonant diagrams We calculate these type of diagrams We find Cross section Parameters For 0.01, incident energy matches the pole and averaged cross section is significantly enhanced (10% ~ 100%) 0.01 is realized for after the inclusion of the radiative corrections in the minimal UED Dark matter abundance The mass of the KK dark matter consistent with the WMAP data is around 950 GeV This result is about 100 GeV above compared to the tree-level result The resonant annihilation process mediated by causes this increase Second KK resonance The s-channel annihilation First KK mass ~ m Second KK mass ~ 2m Energy of two first KK mode second KK mass second KK particle s-channel resonance `natural resonance This resonance is natural! Conclusion Second KK particle effect : `natural resonance Relic abundance of the LKP, s-channel resonance KK dark matter mass consistent with WMAP ~950 GeV (about 100 GeV above the tree result) `Natural resonance affects coannihilation indirect detection collider signature Second KK resonance Coannihilation If degenerate with in mass, coannihilates with tree level coannihilation rate is small s-channel : dipole type interaction Indirect detection DM is almost at rest : good accuracy s-channel second KK B-boson Collider signature Future linear e + e - collider s-channel second KK W-boson M. Battaglia et al. hep-ph/ missing Second KK Higgs mass difference 1 % 0 % 0.5 % 2 % 1.5 % -0.5 % m mhmh (GeV) Cross sections Some diagrams Radiative corrections Weak mixing angles Tree level mass spectrum Abstract SUSY UED similarity LHC new physics superparticle, soft mass stable LSP first KK mode, 1/R mass stable LKP superpartner : single different spin KK mode : tower identical spin angular distribution energy spectrum total cross-section Lepton collider! Compact Linear Collider (CLIC) 1/R=500 GeV, R=20, m h =120 GeV Radiative corrections Radiative corrections remove the degeneracy Lightest KK particle Second KK particles couple to SM particles (KK number violating interaction is forbidden by the momentum conservation) n= Comparison of UED and SUSY UED parameter is chosen naturally MSSM parameter is adjusted to UED parameter Back ground Events 20fb small polar angle missing energy > 2.5 TeV transverse energy < 150 GeV event sphericity > 0.05 Angular distribution and spin measurements UED SUSY UED SUSY 14.4 fb 2.76 fb Background free!! Threshold scans cross section include beamstrahlung confirm New particle Muon energy spectrum UED SUSY UED SUSY For UED, UED,SUSY Resonance SUSYZ, s-channel UEDZ 2, 2 s-channel Resonance!! is kinematically forbidden. is kinematically allowed. is mostly -like and predominantly couple to 1/R = 1350 GeV Weak mixing angle for second KK mode is very small