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STERILE NEUTRINOS and other exotica

STERILE NEUTRINOS and other exotica. Neutrino physics Official do-it list. q 13 ? Improve q 12 , q 23 Mass hierarchy Improve m 1 , m 2 , m 3 Dirac or Majorana CP violation n astronomy. The n MSM model. T. Asaka and M. Shaposhnikov Phys.Lett.B620(2005)17

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STERILE NEUTRINOS and other exotica

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  1. STERILE NEUTRINOSand other exotica

  2. Neutrino physicsOfficial do-it list q13 ? Improve q12 , q23 Mass hierarchy Improve m1, m2, m3 Dirac or Majorana CP violation n astronomy

  3. The nMSM model • T. Asaka and M. Shaposhnikov Phys.Lett.B620(2005)17 • M.Shaposhnokov Nucl.Phys.B763(2007)49 • Minimum extension of the SM to accomodate massive neutrinos • See-saw formula for active neutrinos mn=-MD(1/MI)(MD)T • Majorana mass MI • Dirac mass MD=fv v=174 GeV vac exp val of Higgs field • Usual choice: f as in quark sector, M = 1010-1015 GeV • Alternative choice: small f • Inputs: m(n1)= 10-5 eV, m(n2)= 9 meV, m(n3)= 50 meV and mixings

  4. Three sterile neutrinos • Three singlet RH neutrinos N1 N2 N3 •  N1 with very large lifetime, • Best choice : m(N1) 10 keV •  N2, N3 almost degenerate (leptogenesis) • With masses 100 MeV-few GeV

  5. Decay of a 10 keV neutrino N1 3 n, but also radiative decay • Almost stable DARK MATTER •  Warm dark matter

  6. Limits from cosmology Search for N1 radiative decays Big Bang nucleosynthesis limits for N2, N3 U2 < 10-8 (1/m(GeV))2

  7. Heavy neutrinos at accelerators • Mixed with active neutrinos • In all weak decays they appear at the level U2Nl Their mass is limited by the parent particles p e N m(N) < 130 MeV pm N m(N) < 20 MeV K  e N m(N) < 450 MeV K m N m(N) < 350 MeV … W  e N m(N) < 80 GeV

  8. Change in kinematics Helicity conservation revisited K  eN K mN

  9. Decays of heavy neutrinos Purely weak decays: modes depend on the N mass first open channel e+e-n, then men, m+m-n, e-p+, m-p+…. Lifetime for e+e-n t = 2.8 104 (1/m(MeV)5)(1/U2)

  10. PS191 experiment (1984!) 5 1018 pots 19 GeV

  11. « Typical » event

  12. PRESENT LIMITS

  13. Mixing to the nt • With the NOMAD experiment, 450 GeV p • Source Dst nt

  14. MiniBoone excess ? About 100 events depositing 300-400 MeV energy Obtained with 5 1020 pots of 8 GeV

  15. Possible interpretation Theoretical prejudice in the frame of nMSM model: Decay of the N2 component mixing predominantly to m (testing UNm2) 130 MeV < m < 350 MeV

  16. Guesstimates N produced in Kaon decays  Flux 3 1016 U2 Corrections due to kinematics x 3 And also from focalisation x 5 Decay probability : bgct(m) = 1013 E(MeV)/m6 U2 m = 150 MeV U2 = 10-7 m = 200 MeV U2 = 4 10-8 m = 250 MeV U2 = 2 10-8 NOT EXCLUDED !!

  17. Improving on PS191 • Modern n beam: NuMI (25 years later) • 120 GeV, 16 1020 pots • Large p, K production •  improvement in U2 limits • Furthermore, with D production mass range can be extended to 1.3 GeV

  18. NuMI beam • neutrino flux on the MINERvA detector

  19. (Parenthesis on the LHC) • LHCb • 1012 B mesons/year of 100 GeV/c Mass region extended to 4 GeV • ATLAS/CMS • 3 108 W/year Mass region extended to 50 GeV

  20. Minerna Rough expectations U2 10-6 10-7 10-8 10-9 10-10 B W± K± D± Minerna LHC 0 0.1 0.2 0.3 0.4 GeV 0 0.5 1.0 GeV 0 10 20 30 40 GeV

  21. E.M. interactions of neutrinos • Magnetic moment • Radiative decays • Stimulated conversion g l n2 n1 W

  22. Radiative decays Theory: GIM suppressed t = 7 1043 1/m5 1/U2 (s) Experiment: 1) Mass hierarchy Eg = En/2 SN anti-ne t/m > 6 1015 s/eV Los Alamos nmt /m > 15,4 s/eV 2) Degenerated masses Eg = Endm2/m2 = 2 Endm/m Bugey anti-net /m > 2 10-4 s/eV if dm/m > 10-7 Solar eclipse nmt /m > 100 s/eV if dm2 ~ 10-5 eV2

  23. Matter enhancement Coherent interactions on atomic electrons g n2 e W e n1 t0/tm ~ 3 1024 (Ne/1024)2 (m/E) (1eV/m)4

  24. dE/dx by neutrinos We exposed a HP Ge crystal (140 cm3) to a n beam - First, in the HE (24 GeV) CERN beam Continuous current increase above leakage current during spills (4 pA) proportional to the n beam intensity < 10-5 eV/cm for nm (10-12 of mip) < 10-3 eV/cm for ne This translates into radiative lifetime limits t/m > 10-16 Eg s/eV for 5 10-11 < dm/m < 2 10-8 In vacuum equivalent to t0 > 1019/Eg/m2 (s)

  25. dE/dx by neutrinos, cont. Then, at the Bugey reactor 1 hour exposure, beam off! ne beam (ne /anti-ne = 2 10-4 from 55Fe and 51Cr) Looking for ne n’ + g (explanation of solar deficit) Result: t/m > 3 10-4 s/eV Equivalent to: t0 > 9 1015 s

  26. Stimulated conversion in RF cavity Another possibility to overcome GIM suppression M.C Gonzalès-Garcia, F. Vannucci and J. Castromonte Phys.Lett. B373,153(1996) Idea: RF cavity is a bath of photons (1026g of 10-6 eV) On-off method Majorana neutrinos nm anti-ne or anti-nt Dirac neutrinos nm sterile n R = DN/N = (Q/109)(P/100W)(m/eV)3(eV2/dm2)3(s/t) t0 = 20/R (m/dm2)3 If R<10-2t0 > 4 1015 s for dm2 = 8 10-5 eV2 and m = 1 eV If a signal were to be found, possibility to measure absolute masses and CP effects

  27. Conclusion • Sterile neutrinos: • The nMSM is an appealing model • It is possible to test it simply in the NuMI beam and beyond. • EM interactions of neutrinos: • Large improvements possible, with a very small effort.

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