DARK MATTER Fisica delle Astroparticelle Piergiorgio Picozza a.a

We know that there is dark matter, which is needed to explain the dynamics of stars in Galaxies and of galaxies in clusters. This dark matter does not interact with light, and we do not know witch particles is made of. The peripheral stars of the galaxy M63 rotate around the center so fast that they would fly away in space without the presence of additional mass inside the galaxy. This is indirect evidence for the presence of dark matter What is the Universe made of ?

HALO SUBSTRUCTURE A.Font and J.Navarro, astro- ph/ kpc Milky Way

Dark matter problem Experimentally in spiral galaxies the ratio between the matter density and the Critical density  c is :  lum ≤ 0.01 but from rotation curves must exist a galactic dark halo of mass at least:  halo ≥ 0.1 from gravitational behavior of the galaxies in clusters the Universal mass density is :  halo  0.2 ÷ 0.3 from structure formation theories and analyses of the CMB:  halo ≥ 0. 3 but from big bang nucleosinthesis and analyses of the CMB the Barionic matter cannot be more than: ≤  B ≤ 0. 05

Supersymmetry Particle Sparticle For unbroken supersymmetry they should be degenerate in mass Sparticle have not be found at accelerators so far Supersymmetry is broken Supersymmetry breaking schemes: 1)gravity-mediated scenarios 2)Gauge mediated scenarios 3)Anomaly mediated scenarios

Supersymmetry introduces free parameters: In the MSSM, with Grand Unification assumptions, the masses and couplings of the SUSY particles as well as their production cross sections, are entirely described once 5 parameters are fixed: M 1/2 the mass parameter of supersymmetric partners of gauge fields (gauginos)   the higgs mixing parameters that appears in the neutralino and chargino mass matrices m 0 the common mass for scalar fermions at the GUT scale A the trilinear coupling in the Higgs sector tang  = v 2 / v 1 = / the ratio between the two vacuum expectation values of the Higgs fields (3 S )

In the minimal supersymmetric extension of the Standard Model four neutral spin-1/2 Majorana particles are introduced: the partners of the neutral gauge bosons B, W the neutral CP-even higgsinos H 0 1, H 0 2. Diagonalizing the corresponding mass matrix, four mass eigenstates are obtained. The lightest of these, c, is commonly referred as the neutralino. It is useful to introduce the gaugino fraction Z g defined as: Z g = |N 1 | 2 + |N 2 | 2 and classify the neutralino as higgsino-like when Z g <0.01, mixed when

LEP Experimental lower limit on the mass of the lightest neutralino assuming MSSM (Minimal Standard Supersymmetric Model) M   GeV Limits on Supersymmetry already established hep-ph/

Neutralino WIMPs Assume  present in the galactic halo  is its own antiparticle => can annihilate in galactic halo producing gamma-rays, antiprotons, positrons…. Antimatter not produced in large quantities through standard processes (secondary production through p + p --> p + X) So, any extra contribution from exotic sources (   annihilation) is an interesting signature ie:   --> p + X Produced from (e. g.)   --> q / g / gauge boson / Higgs boson and subsequent decay and/ or hadronisation.

SuperSymmetric Dark Matter Possible signature: Gamma Ray from Neutralino Annihilation Annihilation at rest: bump around Neutralino mass 10 GeV 100 GeV  Diffuse background (4 S ) A=pseudoscalar   =chargino   =neutralino H=Higgs boson

Gamma- Z 0 Annihilation  0 : E'= M  ( 1- m z 2 /4M  2 )

Total photon spectrum from the galactic center from  ann.  lines 50 GeV 300 GeV Bergstrom et al. Infinite energy resolution With finite energy resolution Two-year scanning mode (6 S )

a) CDM neutralinos annihilation in the Galactic halo in minimal SUSY b) In R-parity- violating SUSY

Antiproton fluxes A range of minimal (R-parity-conserving) SUSY predictions of Galactic antiprotons spectrum, with neutralino masses = GeV

PAMELA ANTIPROTONS expectation Secondary production (upper and lower limits) Simon et al. Primary production from   annihilation (m(  ) = 964 GeV) Secondary production Primary production

PAMELA POSITRONS expectation Secondary production ‘Leaky box model’ Secondary production ‘Moskalenko + Strong model’ without reacceleration Primary production from   annihilation (m(  ) = 336 GeV) Primary production for 3 years of operation Secondary production Total

AMS Background from normal secondary production Signal from 964 GeV neutralino annihilations ( astro-ph ) Mass91 data from XXVI ICRC, OG , 1999 Caprice94 data from ApJ, 487, 415, 1997 Caprice98 data from ApJ, 561, (2001), 787. astro-ph/ Distortion of the secondary antiproton flux induced by a signal from a heavy Higgsino- like neutralino. Particles and photons are sensitive to different neutralinos. Gaugino-like particles are more likely to produce an observable flux of antiprotons whereas Higgsino-like annihilations are more likely to produce an observable gamma-ray signature ∆ BESS data from Phys.Rev.Lett, 2000, 84, 1078 AMS data : preliminary

Antiproton Lifetime LEAR Collaboration > 0.08 years Penning trap > 0.28 years APEX Collaboration > 300 kyr Cosmic rays > 0.8 Myr A p lifetime < 13 Myr (CR Galactic storage time) would indicate CPT violation It would appear as a distortion in the energy spectrum

POSITRONS Cosmic ray positrons are produced from decaying mesons in p-A inelastic scattering. WIMPs could contribute to monochromatic positrons from direct annihilation in e + e -, and to continous positrons from other annihilation channels. Excess or bump beginning at a few GeV and extending upward in energy depending on the WIMP mass. Some indication in the present data at high energy: residual unremoved proton background?

Positron Ratio (Phys.Rev. D59 (1999) astro-ph ) Background from normal secondary production Signal from ~ 300 GeV neutralino annihilations Caprice94 data from ApJ, 532, 653, 2000 (ApJ 493, 694, 1998) Caprice98 data from XXVI ICRC, OG , 1999

Distortion of the secondary positron fraction induced by a signal from a heavy neutralino. Baltz & Edsjö Phys.Rev. D59 (1999) astro-ph

Positron with HEAT ICRC 01 p.1867

Positron with HEAT (2) hep- ph/

Positron with HEAT (3) hep- ph/