Pico-charged intermediate particles rescue dark matter interpretation of 511 keV line Yasaman Farzan IPM, Tehran 1 Situation today From CMS and AT L A S : Higgs discovery but nothing more Some news from LHCB Neutrino physics: Overall picture is consistent with 3 ⇥ 3 oscillation paradigm Dark matter 2 3 XENON collaboration, 1705.06655 Competitive result4 from PANDAXII, 1708.06917 5 Why simplest dark paradigm should be true? 6 SM as clue SM sector is sophisticated and non-trivial with a very rich phenomenology 7 Indirect dark matter searches Searching for stable product from dark matter annihilation or decay such as photons positrons antiproton antihydrogen neutrinos …. 8 Indirect dark matter searches 9 Hints for DM from indirect search Signals that went away with further data: 130 GeV line observed by Fermi-LAT Signals that stay robust but go “out of fashion”: PAMELA Signal, INTEGRAL 511 keV line 10 PAMELA and AMS02 positron excess 11 511 keV It has been observed for more than 40 years Leventhal et al., 1978 + e−e annihilation 12 INTEGRAL INTErnational Gamma-Ray Astrophysics Laboratory Launched in 2002 SPI at INTEGRAL of ESA Angular resolution: 2◦ Energy resolution: 2 keV 13 Spectrum 58σ C.L. Va’vra, 1304.0833 14 Morphology of the line Distribution of the line as observed by INTEGRAL/SPI: ESA/Bouchet et al. 15 Flux Siegert et al., arXiv:1512.00325 3 2 1 (0.96 0.07) 10− ph cm− sec− ± ⇥ 16 Some alternative scenarios Radioactive decay: 56Ni 44Ti 13N 26Al Accreting binary sources pulsars supermassive blackhole 17 Dark matter explanation C Boehm, D Hooper, Silk, Casse and Paul, Phys. Rev. Lett. 92 (2004) 101301 Dark matter mass ⇠ few MeV + 4 σ(X + X e−e ) 10− pb ! ⇠ 18 Delayed recombination Reionization rescattering CMB photons Broadening last scattering surface Suppression of temperature and polarization correlation on small scales (large multipoles) Late time Thompson scattering enhanced polarization correlation at large scales 19 Bounds from CMB Wilkinson, Vincent, Boehm and McCabe, PRD 94 (2016) 20 Can p-wave annihilation rescue the DM explanation? + 4 2 σ(X + X e−e ) = (10− pb)v ! 3 At galaxy: 10 − >> velocity at recombination At freeze-out time: + σ(X + X e−e ) = 10 100 pb ! − suppressed relic density 21 Our scenario YF and M Rajaee, arXiv:1708.01137 + X CCC¯ C¯ e−e ! ! The velocity of C will be above escape velocity. 22 Galactic magnetic field Sun et. al 2008 23 24 Larmour radius (8 kpc) sin(2◦) = 280 pc ⇥ 25 Acceleration by supernova shock waves Chuzhoy and Kolb, JCAP 0907 (2009) 014 We need a mechanism for energy loss. The same mechanism that gives charge to C particles also provides a mechanism for cooling. 26 Feldman, Liu and Nath, Phys Rev D 95 (2007) Stueckelberg mechanism X Xµ⌫ δ µ⌫ X Bµ⌫ (@ σ + M X + M B )2 − 4 − 2 µ⌫ − µ 1 µ 2 µ M2 ✏ = 1 δ 1 M1 ⌧ ⌧ Dark photon, γ 0 , mainly composed of Xµ 27 A particularly interesting limit Feldman, Liu and Nath, Phys Rev D 95 (2007) δ = ✏ Decoupling of the sectors g q = ✏ Standard SU(2) coupling e Electric charge of C particles 28 A particularly interesting limit Feldman, Liu and Nath, Phys Rev D 95 (2007) δ = ✏ Decoupling of the sectors g q = ✏ Standard SU(2) coupling e Electric charge of C particles δ = ✏ q max[✏, δ] For 6 still / 29 A particularly interesting limit Feldman, Liu and Nath, Phys Rev D 95 (2007) δ = ✏ Decoupling of the sectors g q = ✏ e Dark photon mass arbitrary given by M1 γ No tree level coupling between 0 and SM fermions 30 Decay of Dark photon kinetically available decays modes for keV dark photons γγ, γγγ, ⌫⌫¯ Landau-Yang theorem γ0 γγ ! 2 6 γ gX q Γγ mγ C 0 ⇠ 0 4⇡(16⇡2)2 γ0 C γ ⌧ =7 1045 years 10 Gyr C γ ⇥ γ C γ0 m 2 g2 q4 ⌫¯ m γ0 X ⇠ γ0 m2 4⇡(16⇡2)2 ✓ Z0 ◆ Z⇤ ⌫ 31 C and γ 0 production in early Universe + ¯ 1 2 e e− CC n˙ C H− 5 q ! =5 10− 11 nγ ⇥ 10− ⇣ ⌘ 2 n˙ +3Hn = σ(CC¯ γ0γ0)v n C C h ! i C 32 Range 11 10 10− <q<3 10− ⇥ n γ0 < 0.1 BBN: nγ 10 eV <mγ0 < 10 keV Subdominant dark matter component Non-relativistic at recombination 33 Dark photon concentration in galaxy 34 nC Bounds on n X fraction Dominant DM component cannot be relativistic [Audren, JCAP 1412 (2014)] f<1% Not all γ 0 are ejected: C should be accumulated 35 What if δ = ✏ 6 γ e e γ0 γ 10 2 3 10− keV ⌧ = 1000 yr ⇥ q m e ✓ 0 ◆ ✓ γ0 ◆ e γ 11 10 q0 gX max[δ, ✏] 10− 3 10− Before recombination ⇠ ⇠ − ⇥ 36 Bounds SLAC bounds on millicharged particles; Prinz et al., PRL 81 (1998) 1175 1 MeV-100 MeV 5 4 q<4.1 10− e 5.8 10− e ⇥ − ⇥ Supernova bound (energy loss) Davidson, Hannestad and Raffelt, JHEP 05 (2000) 03 9 q<10− 37 A few words on dark matter m O(10 MeV) X ⇠ σ(X + X ⌫ + ⌫, ⌫¯ +¯⌫)v =1pb h ! i|tot Bohm et al., PRD 77 (2008) 043516; Farzan, PRD 80 (2009) 073009 Wilkinson et al., PRD 94 (2016) 103525 38 Bounds on electric charge of C versus DM mass 39 Positronium decay + e−e γγ ! Decay at rest: 511 keV line Decay in flight: harder and continuous spectrum 40 Beacom and Yuksel, PRL 97 (2006) 071102 Einj < 3 MeV Assuming zero ionization Size, Casse and Schanne, PRD 74 (2006) 063514 Einj < 7.5 MeV 51 % ionization 41 A fun bound from Voyager Launched on 5th of September, 1977 42 A fun bound from Voyager Containing a piece of Azarbaijani music 43 Voyager out of heliopause Einj < 10 MeV Boudaud Lavalle and Salati, PRL 119 (2017) 021103 Voyager entered interstellar medium in summer 2012 44 Direct detection C relativistic Present Future E =3keV LUX experiment th SuperCDMS Eth =0.056 keV Eth =2keV E =0.02 0.06 keV DAMA CRESST III th − E =0.3 keV Eth < 0.1 keV CRESST II th Edelweiss III 45 46 Dependence on recoil energy Recoil energy Distinctive behavior Different recoil energy dependence from DM signal Even dipole or anapole DM 47 Tests of the scenario Direct dark matter search Positron search by Voyager Studying the correlation of 511 keV line with magnetic field in various dwarf galaxies (e.g. Reticulum II) and milky way 48 Summary Scenario for saving DM interpretation of 511 keV signal from CMB bounds. Dark matter decays to a pair of pico-charged particles that stay in galaxy and eventually annihilate to create electron positron. Testable by low energy DM search experiments Edelweiss II, superCDMS and CRESST III with distinctive dependence on the recoil energy. Search for a positron signal in outer space by Voyager Correlation between galactic magnetic field and 511 keV signal in our galaxy and in dwarf galaxies General scenario applicable for the indirect DM signal other than the 511 keV line 49 Direct annihilation of C pairs to electron positron pair ¯ CC¯ φφ ee¯ CC ! ⇤ σ(CC¯ φφ) 100pb ! ⇠ ⇤ 100 GeV ⇠ 50 In two steps + CC¯ φφ φ e−e ! ! + gφφe−e Supernova decay length smaller than 100 pc 51 Model building 52.