1. Carla Biggio Universidad Autónoma de Madrid Neutrino masses and new physics @ TeV scale HEP 2007, Manchester, England, 19-25/07/07 Based on: Antusch, CB, Fernández-Martínez, Gavela, López-Pavón JHEP 0610:084,2006 [hep-ph/0607020] Abada, CB, Bonnet, Gavela, Hambye in preparation

2. C.Biggio, IFT, Madrid masses beyond the SM masses → (first) signal of new physics BSM smallness of masses → advocate NP @ higher energy scale M

3. C.Biggio, IFT, Madrid masses beyond the SM Heavy fields manifest in the low energy effective theory (SM) via higher dimensional operators UNIQUE d=5 operator: D=5 operator violates lepton number → neutrinos must be Majorana fermions → masses → (first) signal of new physics BSM smallness of masses → advocate NP @ higher energy scale M Weinberg 79

4. C.Biggio, IFT, Madrid Tree-level realizations of see-saw mechanism Type I See-Saw Minkowski, Gell-Mann, Ramond, Slansky, Yanagida, Glashow, Mohapatra, Senjanovic N R fermionic singlet

5. C.Biggio, IFT, Madrid Tree-level realizations of see-saw mechanism Type I See-Saw Minkowski, Gell-Mann, Ramond, Slansky, Yanagida, Glashow, Mohapatra, Senjanovic N R fermionic singlet Type II See-Saw Magg, Wetterich, Lazarides, Shafi, Mohapatra, Senjanovic, Schecter, Valle  scalar triplet

6. C.Biggio, IFT, Madrid Tree-level realizations of see-saw mechanism Type I See-Saw Minkowski, Gell-Mann, Ramond, Slansky, Yanagida, Glashow, Mohapatra, Senjanovic N R fermionic singlet Type II See-Saw Magg, Wetterich, Lazarides, Shafi, Mohapatra, Senjanovic, Schecter, Valle  scalar triplet Type III See-Saw Ma, Hambye et al., Bajc & Senjanovic… t R fermionic triplet

7. C.Biggio, IFT, Madrid d=5 and d=6 operators

8. C.Biggio, IFT, Madrid d=5 and d=6 operators Same d=5 operator but types I and III type II

9. C.Biggio, IFT, Madrid d=5 and d=6 operators type I → renormalization of neutrino kinetic energy type III → renormalization of neutrino kinetic energy + modification of gauge couplings

10. C.Biggio, IFT, Madrid d=5 and d=6 operators type I → renormalization of neutrino kinetic energy type III → renormalization of neutrino kinetic energy + modification of gauge couplings type II → 4 fermions interactions

11. C.Biggio, IFT, Madrid d=5 and d=6 operators Same dependence on Y and M: Y † Y/M 2 types I and III → c d=6 ≈ (c d=5 ) 2 → very suppressed…

12. C.Biggio, IFT, Madrid Can we distinguish among different models? d=5 operator is common to all models for Majorana masses d=6 operator permit to discriminate among different models but generically if Y≈O(1) → c d=6 ≈ (c d=5 ) 2 → very suppressed → To avoid the suppression → lower the scale M

13. C.Biggio, IFT, Madrid Is it possible to lower the scale M without any fine-tuning of the Yukawas Y ? Can we distinguish among different models? d=5 operator is common to all models for Majorana masses d=6 operator permit to discriminate among different models but generically if Y≈O(1) → c d=6 ≈ (c d=5 ) 2 → very suppressed → To avoid the suppression → lower the scale M

14. C.Biggio, IFT, Madrid Is it possible to lower the scale M without any fine-tuning of the Yukawas Y ? YES!!! Can we distinguish among different models? d=5 operator is common to all models for Majorana masses d=6 operator permit to discriminate among different models but generically if Y≈O(1) → c d=6 ≈ (c d=5 ) 2 → very suppressed → To avoid the suppression → lower the scale M

15. C.Biggio, IFT, Madrid Is it possible to lower the scale M without any fine-tuning of the Yukawas Y ? YES!!! Notice: d=5 operator violates lepton number d=6 operators conserve it → natural from the point of view of symmetries… We need to decouple d=5 from d=6 Can we distinguish among different models? d=5 operator is common to all models for Majorana masses d=6 operator permit to discriminate among different models but generically if Y≈O(1) → c d=6 ≈ (c d=5 ) 2 → very suppressed → To avoid the suppression → lower the scale M

16. C.Biggio, IFT, Madrid See-saw @ low scale Light Majorana mass should vanish: inversely proportional to a Majorana scale ≈ 1/M directly proportional to it ≈  ANSATZ: When the breaking of L take place @ a small scale  with  << M the d=5 op. is suppressed with  while the d=6 is unsuppressed

17. C.Biggio, IFT, Madrid See-saw @ low scale YM2YM2 c d=5 ≈ Type II Y † Y M 2 c d=6 ≈

18. C.Biggio, IFT, Madrid See-saw @ low scale Multiple seesaw (for 1 generation) Our ansatz confirmed by Kersten, Smirnov 2007 YM2YM2 c d=5 ≈ Type II Y † Y M 2 c d=6 ≈  <<M N m D <<M N m  ≈

19. C.Biggio, IFT, Madrid See-saw @ low scale Multiple seesaw (for 1 generation) Our ansatz confirmed by Kersten, Smirnov 2007 YM2YM2 c d=5 ≈ Type II Y † Y M 2 c d=6 ≈  <<M N m D <<M N m  ≈ With a low scale we can expect to discover new physics BSM responsible for neutrino masses the near future!!!

20. C.Biggio, IFT, Madrid Experimental information on (Y † Y/M 2 ) Scalar seesaw: bounds from 4 fermions interactions

21. C.Biggio, IFT, Madrid Experimental information on (Y † Y/M 2 ) Scalar seesaw: bounds from 4 fermions interactions Fermionic seesaws: bounds from non-unitarity

22. C.Biggio, IFT, Madrid Experimental information on (Y † Y/M 2 ) Scalar seesaw: bounds from 4 fermions interactions Fermionic seesaws: bounds from non-unitarity 3x3 non-unitary unitary

23. C.Biggio, IFT, Madrid Non-unitarity in types I and III unsuppressed l  → l   Antusch, CB, Fernández-Martínez, Gavela, López-Pavón 2006 affects neutrino oscillations Type I N is not unitary

24. C.Biggio, IFT, Madrid Non-unitarity in types I and III unsuppressed l  → l   Antusch, CB, Fernández-Martínez, Gavela, López-Pavón 2006 affects neutrino oscillations Type I Type III new processes: ex.  → eee @ tree level Abada, CB, Bonnet, Gavela, Hambye in progress N is not unitary

25. C.Biggio, IFT, Madrid Bounds on Yukawas type I W decays, invisible Z decay, universality tests, rare lepton decays → bounds on |NN † | Antusch, CB, Fernández-Martínez, Gavela, López-Pavón 2006 or stronger

26. C.Biggio, IFT, Madrid Bounds on Yukawas type III W decays, invisible Z decay, universality tests, charged leptons Z decays, rare lepton decays (like  →e  and  → eee ) → bounds on |NN † | Abada, CB, Bonnet, Gavela, Hambye in progress Better bounds on off-diag elements due to tree-level  → eee and similar or stronger

27. C.Biggio, IFT, Madrid Bounds on Yukawas type II Non-observation: for Y ≈ 10 -2 -1 → M  >20-200 TeV Abada, CB, Bonnet, Gavela, Hambye in progress or stronger

28. C.Biggio, IFT, Madrid Conclusions D=6 operators discriminate among models of neutrino masses - we have calculated them for the 3 types of seesaws while D=5 op. violates lepton number, D=6 does not → natural ansatz: which allows M≈TeV and large Y D=6 bounded from 4-fermions interactions and unitarity deviations → keep tracking these deviations in the future: they are excellent windows for new physics YM2YM2 c d=5 ≈ Y † Y M 2 c d=6 ≈