Indirect signatures of. Gravitino Dark Matter p.1/33

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1 Indirect signatures of Gravitino Dark Matter Alejandro Ibarra DESY In collaboration with W. Buchmüller, L. Covi, K. Hamaguchi and T. Yanagida (JHEP 0703:037, 2007) G. Bertone, W. Buchmüller, L. Covi (JCAP11(2007)003) D. Tran (Phys.Rev.Lett.100, (2008) and arxiv: ) Planck 08 Barcelona 20th May 2008 Gravitino Dark Matter p.1/33

2 Introduction Many evidences of dark matter at different scales Gravitino Dark Matter p.2/33

3 Introduction Many evidences of dark matter at different scales Gravitino Dark Matter p.2/33

4 Introduction Many evidences of dark matter at different scales Gravitino Dark Matter p.2/33

interacting cold (may be warm) long lived (not necessarily

5 Introduction Many evidences of dark matter at different scales The main features of any dark matter candidate are: weakly interacting cold (may be warm) long lived (not necessarily stable)! lifetime > age of the Universe ( s) Gravitino Dark Matter p.2/33

6 Candidates for dark matter Many! Some interesting candidates are: Massive SM neutrinos (now excluded) Axions Heavy sterile neutrinos Gravitino Dark Matter p.3/33

7 Candidates for dark matter Many! Some interesting candidates are: Massive SM neutrinos (now excluded) Axions Heavy sterile neutrinos Neutralinos (requires R-parity conservation) Gravitinos Gravitino Dark Matter p.3/33

8 Candidates for dark matter Many! Some interesting candidates are: Massive SM neutrinos (now excluded) Axions Heavy sterile neutrinos Neutralinos (requires R-parity conservation) Gravitinos Axinos Gravitino Dark Matter p.3/33

9 Candidates for dark matter Many! Some interesting candidates are: Massive SM neutrinos (now excluded) Axions Heavy sterile neutrinos Neutralinos (requires R-parity conservation) Gravitinos Axinos Lightest Kaluza-Klein particles (B 1, KK graviton), scalar singlets, Q-balls, branons, WIMPzillas, mini-black holes, cryptons, monopoles... Gravitino Dark Matter p.3/33

10 Why the gravitino? Gravitino Dark Matter p.4/33

11 Gravitino dark matter The gravitino is present in any theory with local supersymmetry. When the gravitino is the lightest supersymmetric particle, it constitutes a very interesting (and promising!) candidate for the dark matter of the Universe. Gravitinos are thermally produced in the early Universe by QCD processes. For example: g a G g a G g a G g a G g c + g a + g b + g b g c g b g c g b g c g b g c Also produced by non-thermal processes (inflaton decay, NLSP decay) The existence of relic gravitinos is unavoidable. Whether they constitute the dark matter or not is just a quantitative question. Gravitino Dark Matter p.5/33

12 The interactions of the gravitino with the MSSM particles are fixed by the symmetries From M. Bolz Gravitino Dark Matter p.6/33

13 The interactions of the gravitino with the MSSM particles are fixed by the symmetries The relic abundance is calculable in terms of very few parameters Ω 3/2 h ( T R ) ( ) 100GeV ( meg ) GeV m 3/2 1 TeV NICELY COMPATIBLE WITH LEPTOGENESIS! (T R > 10 9 GeV) Gravitino Dark Matter p.6/33

14 The interactions of the gravitino with the MSSM particles are fixed by the symmetries The relic abundance is calculable in terms of very few parameters Ω 3/2 h ( T R ) ( ) 100GeV ( meg ) GeV m 3/2 1 TeV NICELY COMPATIBLE WITH LEPTOGENESIS! (T R > 10 9 GeV) However, it is undetectable in dark matter searches (direct and indirect) This is a disadvantage rather than a problem. Gravitino Dark Matter p.6/33

15 The ultimate goal would be to construct a consistent thermal history of the Universe. There seems to be a conflict between these three paradigms: Supersymmetric dark matter Big Bang Nucleosynthesis Leptogenesis (T R > 10 9 GeV) The extremely weak interactions of the gravitino can be very problematic in the early Universe Gravitino Dark Matter p.7/33

16 If R-parity is conserved, the NLSP can only decay into gravitinos and SM particles, with a decay rate suppressed by M P : Γ NLSP m 5 NLSP 48πm 2 3/2 M2 P = very long lifetimes. Gravitino Dark Matter p.8/33

17 If R-parity is conserved, the NLSP can only decay into gravitinos and SM particles, with a decay rate suppressed by M P : Γ NLSP m 5 NLSP 48πm 2 3/2 M2 P = very long lifetimes. The leptogenesis constraint T R > 10 9 GeV requires for gravitino dark matter m 3/2 > 5 GeV. Then, τ NLSP 2 days ( m3/2 5 GeV ) 2 ( 150GeV m NLSP The NLSP is present during and after BBN. The decays could jeopardize the abundances of primordial elements. ) 5 Gravitino Dark Matter p.8/33

18 Summary of the implications of a high reheat temperature (T R > 10 9 GeV) for gravitino dark matter: See talk by Kazunori Kohri gravitino LSP neutralino NLSP RH stau NLSP other candidates χ 0 1 ψ 3/2 hadrons Hadrodissociation of primordial elements Catalytic production of 6 Li stop LH sneutrino RH sneutrino Conflict with BBN Conflict with BBN Gravitino Dark Matter p.9/33

19 Summary of the implications of a high reheat temperature (T R > 10 9 GeV) for gravitino dark matter: See talk by Kazunori Kohri gravitino LSP neutralino NLSP RH stau NLSP other candidates χ 0 1 ψ 3/2 hadrons Hadrodissociation of primordial elements Catalytic production of 6 Li stop LH sneutrino RH sneutrino Conflict with BBN Conflict with BBN BBN is the Achilles heel of gravitino dark matter Root of all the problems: the NLSP is very long lived. Simple solution: get rid of the NLSP before BBN R-parity violation Gravitino Dark Matter p.9/33

20 Gravitino DM with broken R-parity When R-parity is broken, the superpotential reads: W = W Rp + µ i (H u L i ) λ ijk(l i L j )e c k + λ ijk(q i L j )d c k + λ ijk(u c id c jd c k) The coupling λ ijk induces the decay of the right-handed stau. For example, eτ R µ ν τ with lifetime: τ eτ 10 3 s ` λ 2 ` m eτ GeV Even with a tiny amount of R-parity violation (λ > ) the stau will decay before the time of BBN. Gravitino Dark Matter p.10/33

21 Gravitino DM with broken R-parity When R-parity is broken, the superpotential reads: W = W Rp + µ i (H u L i ) λ ijk(l i L j )e c k + λ ijk(q i L j )d c k + λ ijk(u c id c jd c k) The coupling λ ijk induces the decay of the right-handed stau. For example, eτ R µ ν τ with lifetime: τ eτ 10 3 s ` λ 2 ` m eτ GeV Even with a tiny amount of R-parity violation (λ > ) the stau will decay before the time of BBN. The lepton/baryon number violating couplings λ, λ, λ can erase the lepton/baryon asymmetry. The requirement that an existing baryon asymmetry is not erased before the electroweak transition implies: λ, λ < 10 7 Campbell, Davidson, Ellis, Olive Fischler, Giudice, Leigh, Paban Dreiner, Ross Plenty of room! < λ, λ < In this range leptogenesis is unaffected. Gravitino Dark Matter p.10/33

22 Interestingly, even though the gravitino is no longer stable, it still constitutes a viable dark matter candidate. It decays for example ψ 3/2 νγ, with lifetime: τ 3/ s ` 3 (Remember: age of the Universe s) λ 2 m3/ GeV Stable enough to constitute the dark matter of the Universe. Takayama, Yamaguchi Gravitino Dark Matter p.11/33

23 Interestingly, even though the gravitino is no longer stable, it still constitutes a viable dark matter candidate. It decays for example ψ 3/2 νγ, with lifetime: τ 3/ s ` 3 (Remember: age of the Universe s) λ 2 m3/ GeV Stable enough to constitute the dark matter of the Universe. Takayama, Yamaguchi In summary: A scenario with the gravitino as LSP with a mass in the range GeV, and a small amount of R-parity violation, < λ, λ < 10 7, provides a good candidate for dark matter and provides a consistent thermal history of the Universe (allows leptogenesis and successful BBN). Gravitino Dark Matter p.11/33

24 Interestingly, even though the gravitino is no longer stable, it still constitutes a viable dark matter candidate. It decays for example ψ 3/2 νγ, with lifetime: τ 3/ s ` 3 (Remember: age of the Universe s) λ 2 m3/ GeV Stable enough to constitute the dark matter of the Universe. Takayama, Yamaguchi In summary: A scenario with the gravitino as LSP with a mass in the range GeV, and a small amount of R-parity violation, < λ, λ < 10 7, provides a good candidate for dark matter and provides a consistent thermal history of the Universe (allows leptogenesis and successful BBN). The gravitino is still undetectable in direct dark matter searches. But the R-parity violating decay of the gravitino into photons, positrons, antiprotons and neutrinos opens the possibility of the indirect detection. Gravitino Dark Matter p.11/33

25 DATA! Gamma rays Gravitinos with a mass of several GeV decay producing photons in the GeV range gamma rays. EGRET measured gamma rays with energies between 30 MeV and 100 GeV. The first analysis from Sreekumar et al. gave an extragalactic flux described by the power law E 2 dj de = ( E 1 GeV) 0.1 (cm 2 str s) 1 GeV, for 50 MeV< E < 10 GeV Close to the prediction for the γ- ray flux from gravitino decay when λ 10 7!! Gravitino Dark Matter p.12/33

26 The more recent analysis by Strong, Moskalenko and Reimer ( 04) shows a power law behaviour between 50 MeV and 2 GeV, but a clear excess between 2 GeV and 50GeV!! HEAO A2,A4(LED) ASCA HEAO-A4 (MED) E 2 dj/de (kev 2 /(cm 2 -s-kev-sr) COMPTEL EGRET v Photon Energy (kev) The photon flux from the decay of gravitinos may be hidden in this excess. Still, many open questions: Extraction of the signal from the galactic foreground Is the signal isotropic/anisotropic? Precise shape of the energy spectrum? GLAST will clarify these issues. Gravitino Dark Matter p.13/33

27 Positrons The HEAT collaboration has reported an excess of positrons at energies > 7 GeV. Same energies as the EGRET excess! HEAT 94/95/00 Positron fraction e + /(e + + e ) 0.1 Background only T [GeV] Gravitino Dark Matter p.14/33

28 Positrons The HEAT collaboration has reported an excess of positrons at energies > 7 GeV. Same energies as the EGRET excess! HEAT 94/95/00 AMS CAPRICE 94 MASS 91 Positron fraction e + /(e + + e ) 0.1 Background only T [GeV] PAMELA will provide an accurate measurement of the positron fraction. Gravitino Dark Matter p.14/33

29 Antiprotons 10-1 Cosmic Ray P BESS(95+97) BESS(93) IMAX CAPRICE p flux (m -2 sr -1 sec -1 GeV -1 ) Bottino Bergstrom Biebar Mitsui λ(r,β) Mitsui λ(r) Kinetic Energy (GeV) The antiproton flux is consistent with the astrophysical models Gravitino Dark Matter p.15/33

30 Gravitino decay channels Light gravitino m 3/2 < M W ψ 3/2 γν Γ(ψ 3/2 γν) = 1 32π U γν 2 m3 3/2 M 2 P ψ 3/2 γ γ ν Gravitino Dark Matter p.16/33

31 Gravitino decay channels Light gravitino m 3/2 < M W ψ 3/2 γν Γ(ψ 3/2 γν) = 1 32π U γν 2 m3 3/2 M 2 P ψ 3/2 γ γ ν not-so-light gravitino 100 GeV < m 3/2 < 300 GeV Z ψ 3/2 Z 0 ν ψ 3/2 Γ(ψ 3/2 Z 0 ν) = 1 32π U Zν 2 m3 3/2 MP 2 f MZ 2 m 2 3/2! Z ν ψ 3/2 W ± l ψ 3/2 W Γ(ψ 3/2 W ± l ) = 2 32π U Wl 2 m3 3/2 MP 2 f MW 2 m 2 3/2! W l Gravitino Dark Matter p.16/33

32 Gravitino decay channels Light gravitino m 3/2 < M W ψ 3/2 γν Γ(ψ 3/2 γν) = 1 32π U γν 2 m3 3/2 M 2 P ψ 3/2 γ γ ν γ s not-so-light gravitino 100 GeV < m 3/2 < 300 GeV Z ψ 3/2 Z 0 ν ψ 3/2 Γ(ψ 3/2 Z 0 ν) = 1 32π U Zν 2 m3 3/2 MP 2 f MZ 2 m 2 3/2! Z ν γ s ψ 3/2 W ± l ψ 3/2 W Γ(ψ 3/2 W ± l ) = 2 32π U Wl 2 m3 3/2 MP 2 f MW 2 m 2 3/2! W l Gravitino Dark Matter p.16/33

33 Gamma-ray flux from gravitino decay The energy spectrum of photons from gravitino decay is dn γ de BR(ψ 3/2 γν) δ E m 3/2 2 + BR(ψ 3/2 Wl) dnw γ de + BR(ψ 3/2 Z 0 ν) dnz γ de Gravitino Dark Matter p.17/33

34 Gamma-ray flux from gravitino decay The energy spectrum of photons from gravitino decay is dn γ de BR(ψ 3/2 γν) δ E m 3/2 2 + BR(ψ 3/2 Wl) dnw γ de + BR(ψ 3/2 Z 0 ν) dnz γ de The branching ratios are determined by the relative size of the mixing parameters» (M2 M 1 )s W c W U eγν M 1 c 2 W + M U 2s 2 ezν W U fwl 2c W M 1 s 2 W + M 2 c 2 W M 2 U ezν Assuming gaugino mass universality at the Grand Unified Scale, U eγν : U ezν : U fwl 1 : 3.2 : 3.5 m 3/2 BR(ψ 3/2 γν) BR(ψ 3/2 Wl) BR(ψ 3/2 Z 0 ν) 10 GeV GeV GeV GeV GeV Gravitino Dark Matter p.17/33

35 Gamma-ray flux from gravitino decay The energy spectrum of photons from gravitino decay is dn γ de BR(ψ 3/2 γν) δ E m 3/2 2 + BR(ψ 3/2 Wl) dnw γ de + BR(ψ 3/2 Z 0 ν) dnz γ de m 3/2 =10 GeV m 3/2 =150 GeV E 2 dn/de γ E 2 dn/de Z W γ E (GeV) E (GeV) Gravitino Dark Matter p.17/33

36 Gamma ray spectrum If gravitinos decay, we expect a diffuse background of gamma rays with two different sources. The decay at cosmological distances gives rise to a perfectly isotropic extragalactic diffuse gamma-ray flux. The decay of the gravitinos in the Milky Way halo gives rise to an anisotropic γ ray flux The precise value of the flux depends on the halo profile. Averaging over all sky, one finds typically D γ /C γ O(1) the halo contribution dominates Gravitino Dark Matter p.18/33

37 Gamma ray spectrum If gravitinos decay, we expect a diffuse background of gamma rays with two different sources. The decay at cosmological distances gives rise to a perfectly isotropic extragalactic diffuse gamma-ray flux. The decay of the gravitinos in the Milky Way halo gives rise to an anisotropic γ ray flux The precise value of the flux depends on the halo profile. Averaging over all sky, one finds typically D γ /C γ O(1) the halo contribution dominates Gravitino Dark Matter p.18/33

38 γ ray spectrum for light gravitinos m 3/2 < M W The energy spectrum from gravitino decay is just a delta function: dn γ de = δ E m 3/2 2 Bertone, Buchmüller, Covi, AI E 2 dj/de (GeV (cm 2 s str) -1 ) extgal halo energy resolution of EGRET: 15% E (GeV) m 3/2 = 10 GeV, τ 3/2 = s Gravitino Dark Matter p.19/33

39 γ ray spectrum for not-so-light gravitinos 100 GeV < m 3/2 < 300 GeV The total flux receives contribution from different sources. U eγν : U ezν : U fwl 1 : 3.2 : 3.5 Gamma-ray spectrum for m 3/2 = 150 GeV AI, Tran 10-6 E 2 dj/de [GeV cm -2 s -1 sr -1 ] E [GeV] Gravitino Dark Matter p.20/33

40 γ ray spectrum for not-so-light gravitinos 100 GeV < m 3/2 < 300 GeV The total flux receives contribution from different sources. U eγν : U ezν : U fwl 1 : 3.2 : 3.5 Gamma-ray spectrum for m 3/2 = 150 GeV AI, Tran 10-6 E 2 dj/de [GeV cm -2 s -1 sr -1 ] 10-7 W -halo W -extgal E [GeV] Gravitino Dark Matter p.20/33

41 γ ray spectrum for not-so-light gravitinos 100 GeV < m 3/2 < 300 GeV The total flux receives contribution from different sources. U eγν : U ezν : U fwl 1 : 3.2 : 3.5 Gamma-ray spectrum for m 3/2 = 150 GeV AI, Tran 10-6 E 2 dj/de [GeV cm -2 s -1 sr -1 ] 10-7 Z-halo Z-extgal E [GeV] Gravitino Dark Matter p.20/33

42 γ ray spectrum for not-so-light gravitinos 100 GeV < m 3/2 < 300 GeV The total flux receives contribution from different sources. U eγν : U ezν : U fwl 1 : 3.2 : 3.5 Gamma-ray spectrum for m 3/2 = 150 GeV AI, Tran 10-6 E 2 dj/de [GeV cm -2 s -1 sr -1 ] 10-7 γ-halo γ-extgal E [GeV] Gravitino Dark Matter p.20/33

43 γ ray spectrum for not-so-light gravitinos 100 GeV < m 3/2 < 300 GeV The total flux receives contribution from different sources. U eγν : U ezν : U fwl 1 : 3.2 : 3.5 Gamma-ray spectrum for m 3/2 = 150 GeV AI, Tran 10-6 E 2 dj/de [GeV cm -2 s -1 sr -1 ] 10-7 background E [GeV] Gravitino Dark Matter p.20/33

44 γ ray spectrum for not-so-light gravitinos 100 GeV < m 3/2 < 300 GeV The total flux receives contribution from different sources. U eγν : U ezν : U fwl 1 : 3.2 : 3.5 Gamma-ray spectrum for m 3/2 = 150 GeV total AI, Tran 10-6 E 2 dj/de [GeV cm -2 s -1 sr -1 ] E [GeV] τ 3/2 = s = U eγν See also talk by Koji Ishiwata Gravitino Dark Matter p.20/33

$Positron fraction The fragmentation of the W and Z bosons produces positrons.$

45 Positron fraction The fragmentation of the W and Z bosons produces positrons. The positrons travel under the influence of the tangled magnetic field of the galaxy and lose energy Complicated propagation equation The computation of the positron fraction requires inputs from particle physics and from astrophysics. The EGRET anomaly fixes m 3/2 150 GeV and τ 3/ s no uncertainties from particle physics. However, there are many uncertainties from astrophysics: halo model? propagation model? Gravitino Dark Matter p.21/33

46 Positron fraction e + /(e + + e ) 0.1 HEAT 94/95/00 AMS CAPRICE 94 MASS 91 Background only T [GeV] Gravitino Dark Matter p.22/33

47 Fix M2 propagation model. Different halo models Positron fraction e + /(e + + e ) 0.1 Moore et al. HEAT 94/95/00 AMS CAPRICE 94 MASS 91 Background only AI, Tran Isothermal 0.01 NFW T [GeV] Gravitino Dark Matter p.22/33

48 Fix M2 propagation model. Different halo models HEAT 94/95/00 AMS CAPRICE 94 MASS 91 AI, Tran 0.1 Positron fraction e + /(e + + e ) Isothermal Moore et al. NFW Background only T [GeV] The scenario of decaying gravitino dark matter predicts a bump in the right energy range, independently of the halo model See also talk by Koji Ishiwata Gravitino Dark Matter p.22/33

49 Fix NFW halo model. Different propagation model Positron fraction e + /(e + + e ) 0.1 M2 HEAT 94/95/00 AMS CAPRICE 94 MASS 91 Background only AI, Tran T [GeV] M1, MED The scenario of decaying gravitino dark matter predicts a bump in the right energy range, independently of the propagation model Gravitino Dark Matter p.23/33

50 An intriguing coincidence... The anomalies in the extragalactic gamma-ray flux and in the positron fraction can be simultaneously explained in this framework. Gamma-ray spectrum for m 3/2 = 150 GeV HEAT 94/95/00 AMS CAPRICE 94 MASS 91 E 2 dj/de [GeV cm -2 s -1 sr -1 ] Positron fraction e + /(e + + e ) 0.1 Isothermal Moore et al. NFW Background only E [GeV] T [GeV] Recall that the scenario of decaying gravitino dark matter was initially proposed not to explain these anomalies, but to reconcile the paradigms of SUSY dark matter, leptogenesis and BBN! This result also applies to any scenario of decaying dark matter with lifetime s which decays predominantly into Z 0 or W ± with momentum 50 GeV. Gravitino Dark Matter p.24/33

51 Antiproton flux Propagation mechanism more complicated than for the positrons. We neglect in our analysis reacceleration and tertiary contributions. The predicted flux suffers from huge uncertainties due to degeneracies in the determination of the propagation parameters. Gravitino Dark Matter p.25/33

52 Antiproton flux Propagation mechanism more complicated than for the positrons. We neglect in our analysis reacceleration and tertiary contributions. The predicted flux suffers from huge uncertainties due to degeneracies in the determination of the propagation parameters. m 3/2 150 GeV and τ 3/ s. NFW halo model Antiproton flux [GeV -1 m -2 s -1 sr -1 ] MAX MED MIN Φ = 500 MV T [GeV] BESS BESS 95 IMAX 92 CAPRICE 94 CAPRICE 98 AI, Tran The MAX and MED model are probably excluded (despite the uncertainties) Gravitino Dark Matter p.25/33

53 The MIN case: m 3/2 150 GeV and τ 3/ s. NFW halo model Antiproton flux [GeV -1 m -2 s -1 sr -1 ] Background BESS BESS 95 IMAX 92 CAPRICE 94 CAPRICE 98 Signal Total AI, Tran Φ = 500 MV T [GeV] Together with the background, the total flux is a factor 2 too large In the view of all the uncertainties in the propagation, it might be premature to rule out the scenario of decaying gravitino dark matter on the basis of this small excess. Gravitino Dark Matter p.26/33

54 Wish list What will make me believe in decaying gravitino dark matter 1 No positive signal from direct dark matter search experiments. Gravitino Dark Matter p.27/33

55 Wish list What will make me believe in decaying gravitino dark matter 1 No positive signal from direct dark matter search experiments. 2 GLAST confirms the EGRET anomaly in the extragalactic gamma ray flux. Gravitino Dark Matter p.27/33

56 Wish list What will make me believe in decaying gravitino dark matter 1 No positive signal from direct dark matter search experiments. 2 GLAST confirms the EGRET anomaly in the extragalactic gamma ray flux. 3 The angular distribution of gamma rays at 1 GeV < E < 100 GeV is consistent with decaying gravitino dark matter. Gravitino Dark Matter p.27/33

57 Wish list What will make me believe in decaying gravitino dark matter 1 No positive signal from direct dark matter search experiments. 2 GLAST confirms the EGRET anomaly in the extragalactic gamma ray flux. 3 The angular distribution of gamma rays at 1 GeV < E < 100 GeV is consistent with decaying gravitino dark matter. Gamma-ray spectrum for m 3/2 = 150 GeV 4 The energy spectrum of gamma rays is consistent with decaying gravitino dark matter m (γ) 3/2, τ(γ) 3/2. E 2 dj/de [GeV cm -2 s -1 sr -1 ] E [GeV] Gravitino Dark Matter p.27/33

58 5 PAMELA confirms the anomaly in the positron fraction. Gravitino Dark Matter p.28/33

59 5 PAMELA confirms the anomaly in the positron fraction. 6 The positron fraction as a function of the positron energy is consistent with decaying gravitino dark matter. m (e+ ) 3/2, ) τ(e+ 3/2 Positron fraction e + /(e + + e ) 0.1 Isothermal Moore et al. HEAT 94/95/00 AMS CAPRICE 94 MASS 91 NFW Background only T [GeV] Gravitino Dark Matter p.28/33

60 5 PAMELA confirms the anomaly in the positron fraction. 6 The positron fraction as a function of the positron energy is consistent with decaying gravitino dark matter. m (e+ ) 3/2, ) τ(e+ 3/2 Positron fraction e + /(e + + e ) 0.1 Isothermal Moore et al. HEAT 94/95/00 AMS CAPRICE 94 MASS 91 NFW Background only T [GeV] 7 m (γ) 3/2 ) m(e+ 3/2 τ (γ) 3/2 ) τ(e+ 3/2. Gravitino Dark Matter p.28/33

61 8 Low energy supersymmetry is discovered at the LHC. Gravitino Dark Matter p.29/33

62 8 Low energy supersymmetry is discovered at the LHC. 9 If the stau is the NLSP, the main decay is τ R τ ν µ, µ ν τ (through λlle c ) cτ lep τ 15 cm ( ) m τ 1 ( λ323 ) 2 400GeV 10 8 Long heavily ionizing charged track followed by a muon track or a jet. A very spectacular signal at colliders! The determination of the R-parity violating coupling would lead to a relation of the gravitino lifetime and the gravitino mass: τ 3/ s ( m 3/2 ) 3 ( m eτ ) ( τeτ ) 150GeV 400GeV 10 8 s Gravitino Dark Matter p.29/33

63 Gamma rays as a thermometer of the Universe? If the scenario of decaying dark matter turns out to be correct, there might be a chance of measuring the temperature of the early Universe. Gamma-ray spectrum for m 3/2 = 150 GeV 10-6 E 2 dj/de [GeV cm -2 s -1 sr -1 ] E [GeV] m 3/2 /2 The thermal relic abundance of gravitinos is given by ( )( ) Ω 3/2 h 2 T R 100 GeV ( meg GeV 1 TeV m 3/2 ) 2 Gravitino Dark Matter p.30/33

64 Gamma rays as a thermometer of the Universe? If the scenario of decaying dark matter turns out to be correct, there might be a chance of measuring the temperature of the early Universe. Gamma-ray spectrum for m 3/2 = 150 GeV 10-6 E 2 dj/de [GeV cm -2 s -1 sr -1 ] E [GeV] m 3/2 /2 If there is only thermal production ( T R Ω3/2 h 2 ) ( m3/2 ) ( m eg GeV GeV 500 GeV ) 2 Gravitino Dark Matter p.30/33

65 Gamma rays as a thermometer of the Universe? If the scenario of decaying dark matter turns out to be correct, there might be a chance of measuring the temperature of the early Universe. Gamma-ray spectrum for m 3/2 = 150 GeV 10-6 E 2 dj/de [GeV cm -2 s -1 sr -1 ] E [GeV] m 3/2 /2 In general ( T R < Ω3/2 h 2 ) ( m3/2 )( m ) 2 eg GeV GeV 500 GeV Gravitino Dark Matter p.30/33

66 Conclusions Gravitino dark matter is a very interesting scenario. Gravitino dark matter with R-parity violation is even more interesting. The potential conflict of BBN and leptogenesis is automatically solved, while preserving the nice features of the gravitino as dark matter. Also, indirect detection might be possible! The anomalies observed in the extragalactic gamma-ray flux (EGRET) and the positron fraction (HEAT) can be simultaneously explained by the decay of the gravitino. Future experiments (GLAST, PAMELA, LHC, XENON, CDMS...) will provide in the near future indications for this scenario or evidences against it. Gravitino Dark Matter p.31/33

67 Isotropy of the signal MeV -1 s -1 sr -2. intensity, cm 2 E V Strong, Moskalenko, Reimer energy (MeV) 5 10 Gravitino Dark Matter p.32/33

68 l b Intensity GeV Description < 10, > ± 0.12 N+S hemispheres < ± 0.15 N hemisphere > ± 0.21 S hemisphere < 10, > ± 0.17 Inner Galaxy N+S < 10, > ± 0.17 Outer Galaxy N+S < 10, > ± 0.17 Positive longitudes N+S < 10, > ± 0.16 Negative longitude N+S > ± 0.22 Inner Galaxy N < ± 0.32 Inner Galaxy S > ± 0.22 Outer Galaxy N < ± 0.34 Outer Galaxy S Gravitino Dark Matter p.33/33

Gravitino Dark Matter p.1/42. with broken R-parity

Gravitino Dark Matter p.1/42. with broken R-parity Gravitino Dark Matter with broken R-parity In collaboration with Alejandro Ibarra DESY W. Buchmüller, L. Covi, K. Hamaguchi and T. Yanagida (JHEP 0703:037, 2007) G. Bertone, W. Buchmüller, L. Covi (JCAP11(2007)003)