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A dark matter candidate from extra dimensions

9/28/06 DESY WORKSHOP “The Dark Universe”. A dark matter candidate from extra dimensions. 1. Regis Marco (SISSA, Trieste). 9/28/06 DESY WORKSHOP “The Dark Universe”. OUTLINE:. The Model

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A dark matter candidate from extra dimensions

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  1. 9/28/06 DESY WORKSHOP “The Dark Universe” A dark matter candidate from extra dimensions 1 Regis Marco (SISSA, Trieste)

  2. 9/28/06 DESY WORKSHOP “The Dark Universe” OUTLINE: • The Model • Z2 symmetry • Dark matter candidate • Coannihilation process • Resonant channels • Results Collaboration with M. Serone and P. Ullio 2 Regis Marco (SISSA, Trieste)

  3. 9/28/06 DESY WORKSHOP “The Dark Universe” Scrucca, Serone, Silvestrini '03 Panico, Serone, Wulzer '05 Panico, Serone, Wulzer '06 THE MODEL 5D gauge theory on S1/Z2 orbifold with gauge-Higgs unification G = SU(3)C x SU(3)W x U(1)' In 4D by orbifold projection G' = SU(3)C x SU(2)W x U(1)Y MATTER CONTENT : Couples of bulk fermions “UP” in reps “DOWN” in reps Chiral fermions localized at y = 0: QL, uR, bR ~ ( Y,Y ) - ( 3,3,1/3) ( 3,6,1/3) 3 Regis Marco (SISSA, Trieste)

  4. 9/28/06 DESY WORKSHOP “The Dark Universe” THE MODEL (2) • Explicit tree-level breaking of the Lorentz SO(4,1) symmetry • Z2 “mirror” symmetry G = SU(3)1,C x SU(3)2,C x SU(3)W x U(1)'1 x U(1)'2 Lagrangian invariant under the Z2 symmetry 1 2 : 4 Regis Marco (SISSA, Trieste)

  5. 9/28/06 DESY WORKSHOP “The Dark Universe” Z2 “MIRROR” SYMMETRY Boundary conditions: A1(y ± 2pR) = A2(y) , A1(-y) = hA2(y) (BC) • Linear combinations A±= (A1 ± A2 )/√2 are periodic / antiperiodic • Under the mirror symmetry: A± ± A± ~ ( Y1,Y1 ) Couples charged under G1 and neutral under G2 Same couplings ~ ( Y2,Y2 ) Couples charged under G2 and neutral under G1 Y±= (Y1 ± Y2 )/√2 periodic / antiperiodic Boundary conditions as (BC) 5 Regis Marco (SISSA, Trieste)

  6. 9/28/06 DESY WORKSHOP “The Dark Universe” STABILITY All SM fields are even under the mirror symmetry The lightest antiperiodic field is absolutely stable! If it is neutral and weakly interacting could be a good dark matter candidate (WIMP) New parity in a ED model different from KK parity can provide the stability of a DM candidate No need of Universal extra dimensions 6 Regis Marco (SISSA, Trieste)

  7. 9/28/06 DESY WORKSHOP “The Dark Universe” WHO IS THE LIGHTEST? Mass of antiperiodic fields: Gauge bosons: Fermions: Suppose r' < rS and r' < k The n = 0 mode of the gauge boson A_ is the lighest (with mass ~ 1/2R) 7 Regis Marco (SISSA, Trieste)

  8. 9/28/06 DESY WORKSHOP “The Dark Universe” A_ as DM CANDIDATE It is the analogous of the first kk mode of the hypercharge gauge boson in UED A_ is the gauge boson of the abelian gauge group U(1)_ Coupling only with bulk fermions. But SM fermions are a mixture of bulk and boundary fermions Annihilation cross section is (highly) reduced At the scale allowed from EW bound (i.e. 1/R ~ 4-5 TeV) A_ overcloses the Universe! 8 Regis Marco (SISSA, Trieste)

  9. 9/28/06 DESY WORKSHOP “The Dark Universe” “STRONG” COANNIHILATIONS Is it possible to have a WIMP with Multi-TeV mass? Yes, if the DM candidate coannihilates with strong interacting particles (i.e. gluons or colored fermions) MUED example: B(1) - COANNIHILATION WITH g(1) Burnell, Kribs '05 Kong, Matchev '05 Wh2 9 Regis Marco (SISSA, Trieste)

  10. 9/28/06 DESY WORKSHOP “The Dark Universe” COANNIHILATION WITH g_ (without resonances) • The mass splitting is given by the ratio rs / r' • The production of quark pairs in s-channel do not suffer of the suppression due to the fermion localization • The dominant cross section comes from the process g_+g_ gSM+gSM • The running of as is negligible Wh2 A_ can be a good DM candidate! 10 Regis Marco (SISSA, Trieste)

  11. 9/28/06 DESY WORKSHOP “The Dark Universe” RESONANCES Kakizaki, Matsumoto, Sato, Senami '05 q g_(0) _ q g_(0) g+(1) This process can occur since: KK number violation at tree level (at loop level in UED) Localized fermions And it is resonant because: g+(1) mass = 2 g-(0) mass at tree level 11 Regis Marco (SISSA, Trieste)

  12. 9/28/06 DESY WORKSHOP “The Dark Universe” COANNIHILATION WITH g_ (including resonances) _ The decay rate of g+(1) q + q is significantly higher than the mass splitting induced by radiative corrections. Wh2 The resonance highly increases the thermally averaged cross section! 12 Regis Marco (SISSA, Trieste)

  13. 9/28/06 DESY WORKSHOP “The Dark Universe” CONCLUSIONS • A new Z2 symmetry (different from KK parity) can guarantee the stability for a DM candidate. • The Multi-Tev mass region for a WIMP is not excluded since “strong” coannihilations and resonances. • There is a significant fraction of parameter space in which A_ is a DM candidate with the correct relic density. • Need of a fine-tuning estimation (and possible other coannihilation processes) to have a better judgment of the results. 13 Regis Marco (SISSA, Trieste)

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