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Previous searches for Heavy Neutral Leptons (and other beam-dump exotics)

Previous searches for Heavy Neutral Leptons (and other beam-dump exotics). Alexandre Rozanov 10 June 2014. Standard Coupling Heavy Neutral Lepton. Abreu al. Phys Lett B274 230 (1992). Stable Dirac m> 45 GeV 95% CL Stable Majorano m> 39.5 GeV 95% CL

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Previous searches for Heavy Neutral Leptons (and other beam-dump exotics)

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  1. Previous searches for Heavy Neutral Leptons (and other beam-dump exotics) Alexandre Rozanov 10 June 2014 A.Rozanov Zurich 10 June 2014

  2. Standard Coupling Heavy Neutral Lepton Abreu al. Phys Lett B274 230 (1992) • Stable Dirac m> 45 GeV 95% CL • Stable Majorano m> 39.5 GeV 95% CL • Unstable, Dirac coupling to e,μ,τ m> 90.3 GeV • Unstable, Majorano coupling to e,μ,τ m> 80.5 GeV • In Standard Model with one Higgs doublet sequential chiral Fourth generation with mN4>55 GeV is excluded by electroweak results with Tevatron and LHC Higgs searches: gg->triangleQ4->H is enhanced • Small niche with 50 < mN <55 GeV due to H-> N N dominant decay, is now almost excluded • In SM extension with two Higgs doublets fourth generation is allowed Achard et al. Phys Lett B517 75 (2001) Vysotsky, Rozanov Phys Lett B700 313 (2011) A.Rozanov Zurich 10 June 2014

  3. Search for Heavy Neutrino • sterile mixed with standard neutrino by matrix U, so small effective couplings • N produced in pp, decays in empty space equipped with detectors • PS 191 experiment at CERN 19 GeV PS horn neutrino beam • CHARM experiment at CERN 400 GeV SPS beam-dump • NuTeV experiment on Fermilab 800 GeV Quad neutrino beam A.Rozanov Zurich 10 June 2014

  4. Beam dump with PS191 • By product of PS neutrino beam • 19 GeV protons at 128 m distance at 40 mrads • Total exposure of 1.4 1019 protons • He filled decay region of 12 meters A.Rozanov Zurich 10 June 2014

  5. PS191 decay channels • N -> e e νN -> μ μ ν • N -> μ e νN -> e π • N -> μ π N -> e π π0 • U2< 2.0 10-9at mN=350 MeV A.Rozanov Zurich 10 June 2014

  6. PS191 results • π and K decays Bernardi et al. Phys Lett B203 332 (1988) π -> e N K -> e N K -> μ N A.Rozanov Zurich 10 June 2014

  7. Beam Dump with CHARM experiment • 400 GeV protons at 480 m distance at 10 mrad • Total exposure 2.4 1018 protons • Air decay region of 35 m A.Rozanov Zurich 10 June 2014

  8. CHARM decay channels • N -> μ μ ν • N -> e e ν • N -> μ e ν • N -> μ X (in WBB) A.Rozanov Zurich 10 June 2014

  9. Electron-neutrino coupling • U2eN< 1.0 10-7 at mN=1.5 GeV A.Rozanov Zurich 10 June 2014

  10. Muon-neutrino coupling Dorenbosh et al. Phys Lett B166 473 (1986) • U2μN< 0.8 10-7 at mN=1.5 GeV A.Rozanov Zurich 10 June 2014

  11. Tau-neutrino coupling • mostly isosinglet heavy neutrino coupled to tau • re-analysis of CHARM beam dump A.Rozanov Zurich 10 June 2014

  12. Tau-neutrino coupling results Orloff, Rozanov, SantoniPhys Lett B550 8 (2002) • U2τN< 1.5 10-4at mN=180 MeV SN1987a NOMAD CHARM Nucleosynthese A.Rozanov Zurich 10 June 2014

  13. Beam dump with NuTeV • By product of sign selected Quad beam • 800 GeV protons at 1400 m distance at 7.8 mrads • Total exposure of 2.5 1018 protons • He filled decay region of 34 meters A.Rozanov Zurich 10 June 2014

  14. NuTev decay channels • N -> μ μ ν • N -> μ e ν • N -> μ π • N -> μ ρ A.Rozanov Zurich 10 June 2014

  15. Muon-neutrino coupling Vaitaitis et al. Phys Rev Lett 83 4943 (1999) • U2μN < 0.6 10-7 at mN=1.6 GeV A.Rozanov Zurich 10 June 2014

  16. Exotics: White Quarks in beam dump • Original idea of V. Gribov of screening of color charge via vacuum polarization • M.Strikman point to possible beam-dump search • σ ~ σπinel (mπ/mglue)2 ~ 10-3σπinel • White Quarks produced in pp collisions can penetrate through muon shielding • CHARM experiment searched WQ in beam dump with 2 1018 protons and charge measurements by dE/dx in the scintillators Strikman Phys Lett B105 230 (1981) Bergsma et al. Z. Phys. C24 217 (1984) A.Rozanov Zurich 10 June 2014

  17. White Quarks in CHARM Bergsma et al. Z. Phys. C24 217 (1984) • CHARM experiment searched WQ in beam dump with 2 1018 protons and charge measurements by dE/dx in the scintillators • σ < 10-40 cm2 mWQ < 10 GeV A.Rozanov Zurich 10 June 2014

  18. SHIP vs CHARM • Total exposure factor = 2.0 1020 /2.4 1018 = 83 • Distance = (480m/110m)2=19 • Surface = ( 18m2 /9m2)= 2 • Decay length = 100m/35m =3 • Total = 83*19*2*3= 9462 plus better efficiency • Four order more sensitivity for Heavy Neutrino • Factor 3000 more sensitivity for White Quarks A.Rozanov Zurich 10 June 2014

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