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Leptoquarks

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  1. Lepton number violation at the LHC with Leptoquarks and Diquarks Hiroaki SUGIYAMA (Maskawa Inst., Kyoto Sangyo Univ.) Contents • Introduction, Motivation • The Model - “colored Zee-Babu model” - • Lepton Number Violation at the LHC • Summary based on ‘M. Kohda, HS, K. Tsumura, PLB718, 1436 (2013)’

  2. Introduction -Neutrino Oscillation- Neutrino masses, mixings, and oscillations Massive neutrinos can be mixed : flavor eigenstates (weak interaction) : mass eigenstates (propagation) : Maki-Nakagawa-Sakata matrix (mixing) (quark sector : Cabibbo-Kobayashi-Maskawa matrix) Flavor transitions (oscillations) are possible : masses : distance : energy

  3. Two Neutrino Case (good approximation) P(transition) accuracy for accuracy for first oscillation maximum : good set up (E, L) of experiments to obtain and

  4. e.g., Measurement in KamLAND experiment 55 Japanese nuclear power reactors Kamioka mine apparently oscillating ! S. Abe et al., PRL100, 221803 Neutrino masses are necessary We have evidence of oscillations

  5. ? ? Current knowledge on neutrino masses and mixings reactor T2K atmospheric accelerator solar KamLAND or “inverted” “normal”

  6. Introduction -Neutrino Mass- Neutrino masses are extremely smaller than other fermion masses. neutrino-specific mechanism to generate their masses ? c.f. for “Unnatural” Neutrino-specific mass term Majorana : Allowed only for neutrinos Lepton number violation

  7. Majorana mass & L#V processes Majorana neutrino L#V process (tiny mass) (tiny rate) e.g., Neutrinoless double beta decay

  8. Motivation Input : Small Output : Small rate of L#V Input : Unsuppressed L#V Output : Suppressed Black box : TeV-scale particles No

  9. Two-Loop Neutrino Mass Zee-Babu Model A. Zee, NPB264, 99 (1986) K.S. Babu, PLB203, 132 (1988) colored version two colored loops

  10. Lepton number violation at the LHC with Leptoquarks and Diquarks Hiroaki SUGIYAMA (Maskawa Inst., Kyoto Sangyo Univ.) Contents • Introduction, Motivation • The Model - “colored Zee-Babu model” - • Lepton Number Violation at the LHC • Summary based on ‘M. Kohda, HS, K. Tsumura, PLB718, 1436 (2013)’

  11. The Model - Zee-Babu Model - colored Briefly mentioned in ‘K.S. Babu and C.N. Leung, NPB619, 667 (2001)’ Scalar Leptoquark Scalar Diquark soft L#V term (no B#V) Two-loop neutrino mass color color

  12. A Benchmark Point LQ Yukawa : DQ Yukawa : Scale : satisfy constraints (couplings, masses) agree with neutrino oscillation data

  13. Lepton number violation at the LHC with Leptoquarks and Diquarks Hiroaki SUGIYAMA (Maskawa Inst., Kyoto Sangyo Univ.) Contents • Introduction, Motivation • The Model - “colored Zee-Babu model” - • Lepton Number Violation at the LHC • Summary based on ‘M. Kohda, HS, K. Tsumura, PLB718, 1436 (2013)’

  14. Large Hadron Collider Higgs at CMS Higgs at ATLAS 4 Apr. 2008 4 Apr. 2008 4 Jul. 2012 4 Jul. 2012 (cf. Tevatron: at ) collider at (cf. 26.4km loop subway in Nagoya, Japan) 26.7km ring (cf. 21.7km loop line in Osaka, Japan)

  15. 8.5 km

  16. L#V Process at the LHC without missing No missing energy No missing L# Definite total L# of final states Evidence for L#V

  17. without missing L#V No SM process in principle No mimic event in SM Hard Clear evidence for L#V

  18. (same for scalar) T. Han et al., JHEP 1012, 085 (2010) at for

  19. vs. For fixed Large Good for & Bad for Small Bad for & Good for is preferred Benchmark point

  20. is small BUT is also small. Sizable @ Benchmark point w/o missing w/ missing w/o missing ( )

  21. Benchmark point & LHC with

  22. Summary Zee-Babu Model with Leptoquark and Diquark Colored Suppressed neutrino mass ( two-loop, , ) color color Unsuppressed L#V process at the LHC without missing

  23. Backup

  24. L#V Process at the LHC without missing at even for for for

  25. Production Cross Section T. Han, I. Lewis, and Z. Liu, JHEP 1012, 085 (2010)

  26. Bounds on Masses Leptoquark mass (for ) CMS : PRD86, 052013 (2012) PLB709, 158 (2012) ATLAS : EPJC72, 2151 (2012) Diquark mass No analysis for CMS : arXiv:1302.4794 cf.

  27. Bounds on Masses Leptoquark mass CMS : PRD86, 052013 (2012) JHEP1212, 055 (2012) arXiv:1210.5629

  28. Bounds on Masses Leptoquark mass PLB709, 158 (2012) ATLAS : EPJC72, 2151 (2012)

  29. Bounds on Masses Diquark mass No analysis for cf. CMS : arXiv:1302.4794

  30. Constraints on New Yukawa Couplings LQ Yukawa M. Carpenter and S. Davidson, EPJC70, 1071 (2010) ( conversion ) Constraint : Benchmark : ( meson decay ) Constraint : Benchmark : Constraint : MEG, PRL107, 171801 (2011) MEG, arXiv:1303.0754 Benchmark :

  31. DQ Yukawa UTfit, JHEP0803, 049 (2008) mixing Benchmark point mixing mixing

  32. LFV We ignore . No Type-II or Type-X THDMs ( or are - odd) or - triplet Leptoquark Dangerous

  33. Neutrinoless Double Beta Decay @ Benchmark point