Puzzles of Dark Matter Searches - a signature for Composite Dark Matter?

1. Puzzles of Dark Matter Searches - a signature for Composite Dark Matter? Presented to Seminar in ULB, 13.04.2010

2. Outlines • Puzzles of Direct Dark matter searches • Physical reasons for new stable quarks and/or leptons • Exotic forms of composite dark matter, their cosmological evolution and effects in underground detectors • Cosmic-ray and accelerator search for charged components of composite dark matter

3. Dark Matter – Cosmological Reflection of Microworld Structure Dark Matter should be present in the modern Universe, and thus is stable on cosmological scale. This stabilty reflects some Conservation Law, which prohibits DM decay. Following Noether’s theorem this cosnservation law should correspond to a (nearly) strict symmetry of microworld.

4. Direct search for DM (WIMPs) DM can consist of Weakly InteractingMassive Particles (WIMPs). Such particles can be searched by effects of WIMP-nucleus interactions. elastic scattering non-pointlike nucleus

5. Direct search for DM (WIMPs) Minimization of background • Installation deeply underground • Radioactively pure materials • Annual modulation DM does not participate in rotation around GC.

6. Direct search for DM (WIMPs) Experiment DAMA (NaI) Results of 7 years of observation (1995-2002). DAMA/NaI (7 years) + DAMA/LIBRA (4 years) total exposure: 300555 kg´day = 0.82 ton´yr

7. Other searches for DM (WIMPs) Experiment DAMA (NaI) vs other underground experiments: Interpretation in terms of scalarAX-interaction. Experiment DAMA/NaI+DAMA/Libra vs other underground experiments: two eventswere observed;the probability of observing two or more background events is23% Analysis depends essentially on assumption about distribution of DM in vicinity of Solar system. On this picture a quite simplified assumption was adopted. DAMA(NaI) under variety of assumptions Minimal SUSY model predictions 7 0912.3592 arXive: 0808.3607 [astro-ph]

8. Direct search for DM (SDI WIMPs) Experiment DAMA/NaI+DAMA/Libravs other underground experiments: Experiment DAMA (NaI) vs other underground experiments: Interpretation in terms of spin-spinAX-interaction. Super-Kamiokande (see slides 11-15) 8

9. Direct search for DM (SIMPs) Rocket experiment XQC. If DM consists of Strongly Interacting Massive Particles (SIMPs), they could be slowed down by ordinary matter and become insensitive for underground detectors. Such particles could be searched for in X-cosmic ray experiment XQC, aimed at observation of X-rays and realized during a rocket flight. XQC experiment data taking time: ~100s, material of detector: Si+HgTe, energy deposit range of sensitivity: 25-1000 eV, the range being good for extraction of SIMP-nucleus interactions event from background: 25-60 eV. For scalar XA-interaction

10. Dark Matter from Charged Particles? By definition Dark Matter is non-luminous, while charged particles are the source of electromagnetic radiation. Therefore, neutral weakly interacting elementary particles are usually considered as Dark Matter candidates. If such neutral particles with mass m are stable, they freeze out in early Universe and form structure of inhomogeneities with the minimal characterstic scale • However, if charged particles are heavy, stable and bound within neutral « atomic » states they can play the role of composite Dark matter. • Physical models, underlying such scenarios, their problems and nontrivial solutions as well as the possibilities for their test are the subject of the present talk.

11. Componentsof composite darkmatter: • Tera-fermions E and U of S.L.Glashow’s • Stable U-quark of 4-th family • AC « leptons » fromalmost commutative geometry • Technibaryons and technileptonsfromWalking Technicolor (WTC) • Stable U-quarks of 5th family in the approach, unifying spins and charges, by N. Mankoc-Borstnik

14. Glashow’s tera-fermions SU(3)xSU(2)xSU(2)xU(1) Tera-fermions(N,E,U,D)  W’,Z’, H’,  and g +problem of CP-violation in QCD+problem of neutrino mass +(?) DM as [(UUU)EE] tera-helium (NO!) Very heavy and unstable 6 10 m~500 GeV, stable m~3 TeV, (meta)stable m~5 TeV, D  U +…

16. Cosmological tera-fermion asymmetry • To saturate the observed dark matter of the Universe Glashow assumed tera-U-quark and tera-electron excess generated in the early Universe. • The model assumes tera-fermion asymmetry of the Universe, which should be generated together with the observed baryon (and lepton) asymmetry However, this asymmetry can not suppress primordial antiparticles, as it is the case for antibaryons due to baryon asymmetry

22. (Ep) catalyzer • In the expanding Universe no binding or annihilation is complete. Significant fraction of products of incomplete burning remains. In Sinister model they are: (UUU), (UUu), (Uud), [(UUU)E], [(UUu)E], [(Uud)E], as well as tera-positrons and tera-antibaryons • Glashow’s hope was that at T<25keV all free E bind with protons and (Ep) « atom » plays the role of catalyzer, eliminating all these free species, in reactions like But this hope can not be realized, since much earlier all the free E are trapped by He

24. « No go theorem » for -1 charge components • If composite darkmatterparticles are « atoms », binding positive P and negative E charges, all the free primordial negative charges E bindwith He-4, as soon as heliumiscreated in SBBN. • Particles E withelectric charge -1 form +1 ion [E He]. • This ion is a form of anomaloushydrogen. • Its Coulomb barrierprevents effective binding of positivelychargedparticles P with E. Thesepositivelychargedparticles, boundwithelectrons, becomeatoms of anomalousistotopes • Positivelycharged ion is not formed, if negativelychargedparticles E have electric charge -2.

25. 4th family from heterotic string phenomenology • 4th family can follow from heterotic string phenomenology as naturally as SUSY. • GUT group has rank (number of conserved quantities) 6, while SM, which it must embed, has rank 4. This difference means that new conserved quantities can exist. • Euler characterics of compact manifold (or orbifold) defines the number of fermion families. This number can be 3, but it also can be 4. • The difference of the 4th family from the 3 known light generations can be explained by the new conserved quantity, which 4th generation fermions possess. • If this new quantum number is strictly conserved, the lightest fermion of the 4th generation (4th neutrino, N) should be absolutely stable. • The next-to-lightest fermion (which is assumed to be U-quark) can decay to N owing to GUT interaction and can have life time, exceeding the age of the Universe. • If baryon asymmetry in 4th family has negative sign and the excess of anti-U quarks with charge -2/3 is generated in early Universe, composite dark matter from 4th generation can exist and dominate in large scale structure formation.

26. 4-th family m~50 GeV, (quasi)stable 100 GeV<m<~1TeV, E ->N l,… unstable 220 GeV<m<~1TeV, U ->N + light fermions Long-living wihout mixing with light generations 220 GeV<m<~1TeV, D ->U l,… unstable Precision measurements of SM parameters admit existence of 4th family, if 4th neutrino has mass around 50 GeV and masses of E, U and D are near their experimental bounds. If U-quark has lifetime, exceeding the age of the Universe, and in the early Universe excess of anti-U quarks is generated, primordial U-matter in the form of ANti-U-Tripple-Ions of Unknown Matter (anutium). can become a -2 charge constituent of composite dark matter 4th neutrino with mass 50 GeV can not be dominant form of dark matter. But even its sparse dark matter component can help to resolve the puzzles of direct and indirect WIMP searches.

27. Dominant form of 4th generationdarkmatter: O-helium formation But it goes only after He is formed at T ~100 keV The size of O-helium is It catalyzes exponential suppression of all the remaining U-baryons with positive charge and causes new types of nuclear transformations

28. O-Helium: alpha particle with zero charge • O-helium looks like an alpha particle with shielded electric charge. It can closely approach nuclei due to the absence of a Coulomb barrier. For this reason, in the presence of O-helium, the character of SBBN processes can change drastically. • This transformation can take place if This condition is not valid for stable nuclids, participating in SBBN processes, but unstable tritium gives rise to a chain of O-helium catalyzed nuclear reactions towards heavy nuclides.

29. OHe catalysis of heavy element production in SBBN

30. OHe induced tree of transitions After K-39 the chain of transformations starts to create unstable isotopes and gives rise to an extensive tree of transitions along the table of nuclides

31. Complicated set of problems • Successive works by Pospelov (2006) and Kohri, Takayama (2006) revealed the uncertainties even in the roots of this tree. • The « Bohr orbit » value is claimed as good approximation by Kohri, Takayama, while Pospelov offers reduced value for this binding energy. Then the tree, starting from D is possible. • The self-consistent treatment assumes the framework, much more complicated, than in SBBN. Nuclear physics of OHe reactions should be evolved

32. O-helium dark matter • Energy and momentum transfer from baryons to O-helium is not effective and O-helium gas decouples from plasma and radiation • O-helium dark matter starts to dominate • On scales, smaller than this scale composite nature of O-helium results in suppression of density fluctuations, making O-helium gas more close to warm dark matter

33. Anutium component of cosmic rays • Galactic cosmic rays destroy O-helium. This can lead to appearance of a free anutium component in cosmic rays. Such flux can be accessible to PAMELA and AMS-02 experiments

34. Rigidity of Anutium component Difference in rigidity provides discrimination of U-helium and nuclear component

35. O-helium in Earth • Elastic scattering dominates in the (OHe)-nucleus interaction. After they fall down terrestrial surface the in-falling OHe particles are effectively slowed down due to elastic collisions with the matter. Then they drift, sinking down towards the center of the Earth with velocity

36. O-helium experimental search? • In underground detectors, (OHe) “atoms” are slowed down to thermal energies far below the threshold for direct dark matter detection. However, (OHe) nuclear reactions can result in observable effects. • O-helium gives rise to less than 0.1 of expected background events in XQC experiment, thus avoiding severe constraints on Strongly Interacting Massive Particles (SIMPs), obtained from the results of this experiment. It implies development of specific strategy for direct experimental search for O-helium.

37. Superfluid He-3 search for O-helium • Superfluid He-3 detectors are sensitive to energy release above 1 keV. If not slowed down in atmosphere O-helium from halo, falling down the Earth, causes energy release of 6 keV. • Even a few g existing device in CRTBT-Grenoble can be sensitive and exclude heavy O-helium, leaving an allowed range of U-quark masses, accessible to search in cosmic rays and at LHC and Tevatron

38. O-helium concentration in Earth The O-helium abundance the Earth is determined by the equilibrium between the in-falling and down-drifting fluxes. The in-falling O-helium flux from dark matter halo is where Vhis velocity of Solar System relative to DM halo (220 km/s), VE is velocity of orbital motion of Earth (29.5 km/s) and is the local density of O-helium dark matter. At a depth L below the Earth's surface, the drift timescale is ~L/V. It means that the change of the incoming flux, caused by the motion of the Earth along its orbit, should lead at the depth L ~ 105 cm to the corresponding change in the equilibrium underground concentration of OHe on the timescale

39. Annual modulation of O-helium concentration in Earth The equilibrium concentration, which is established in the matter of underground detectors, is given by where T=1yr and tois the phase. The averaged concentration is given by and the annual modulation of OHe concentration is characterized by The rate of nuclear reactions of OHe with nuclei is proportional to the local concentration and the energy release in these reactionsleads to ionization signal containing both constant part and annual modulation.

40. OHe solution for puzzles of direct DM search • OHe equilibrium concentration in the matter of DAMA detector is maintained for less than an hour • The process is possible, in which only a few keV energy is released. Other inelastic processes are suppressed • Annual modulations in inelastic processes, induced by OHe in matter. No signal of WIMP-like recoil • Signal in DAMA detector is not accompanied by processes with large energy release. This signal corresponds to a formation of anomalous isotopes with binding energy of few keV

41. Formation of OHe-nucleus bound system Due to exponential tail of nuclear Yukawa force OHe is attracted by nucleus. At the distance of order of the size of OHe Coulomb barrier is switched on. If He emits a photon, OHe forms a bound system with nucleus with binding energy of few KeV. Vcul= Vnuc= E~few keV The depth of the well is maximal for A~10-20

42. Few keV Level in OHe-nucleus system in NaI • The problem is reduced to a quantum mechanical problem of finding energy level of OHe bound state in the spherically symmetric potential well, formed by Yukawa attraction and Coulomb barrier for He nucleus component of OHe in vicinity of a nucleus. • The numerical solution for this problem is simplified for rectangular wells and walls, giving a few keV level for Na and I .

43. Few keV Levels in OHe-Na and OHe-I systems

44. Levels in OHe-Ge system

45. Levels in OHe-Xe system

46. Rate of OHe-nucleus radiative capture As soon as the energy of level is found one can use the analogy with radiative capture of neutron by proton with the account for: • Absence of M1 transition for OHe-nucleus system (which is dominant for n+p reaction) • Suppression of E1 transition by factor f~10-3, corresponding to isospin symmetry breaking (in the case of OHe only isoscalar transition is possible, while E1 goes due to isovector transition only)

47. Reproduction of DAMA/NaI and DAMA/LIBRA events The rate of OHe radiative capture by nucleus with charge Z and atomic number A to the energy level E in the medium with temperature T is given by Formation of OHe-nucleus bound system leads to energy release of its binding energy, detected as ionization signal. In the context of our approach the existence of annual modulations of this signal in the range 2-6 keV and absence of such effect at energies above 6 keV means that binding energy of Na-OHe and I-OHe systems in DAMA experiment should not exceed 6 keV, being in the range 2-4 keV for at least one of these elements.

48. Annual modulation of signals in DAMA/NaI and DAMA/LIBRA events The amplitude of annual modulation of ionization signal (measured in counts per day per kg, cpd/kg) is given by

49. Rates of OHe capture in other detectors Since OHe capture rate is proportional to the temperature, it should be suppressed in cryogenic detectors. However, for the size of cryogenic devices less, than few tens meters, OHe gas in them has the temperature of the surrounding matter and the suppression relative to room temperature is only ~mA/mo.

50. Excessive positrons in Integral Taking into account that in the galactic bulge with radius ∼ 1 kpc the number density of O-helium can reach the value one can estimate the collision rate of O-helium in this central region: At the velocity of particules in halo, energy transfer in such collisions is E ∼ 1MeV. These collisions can lead to excitation of O-helium. If 2S level is excited, pair production dominates over two-photon channel in the de-excitation by E0 transition and positron production with the rate is not accompanied by strong gamma signal. This rate of positron production is sufficient to explain the excess of positron production in bulge, measured by Integral.