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Towards precision lepton flavour physics

Towards precision lepton flavour physics. n. Some reflections…. n have brought us many clues for a deeper understanding in the SM and continue to do so: They were the key to the weak interactions first "almost" invisible carriers of energy

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Towards precision lepton flavour physics

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  1. Towards precision lepton flavour physics n

  2. Some reflections… • n have brought us many clues for a deeper understanding • in the SM and continue to do so: They were the key to the weak interactions • first "almost" invisible carriers of energy • first realization of an “almost” Weyl fermion: only one helicity state! • first state with only a chiral gauge charge

  3. We got the SM but not quite a deeper understanding chiral gauge theories are finely tunned and extremely hard to get as effective theories: • anomaly cancellation • complex vacuum structure that we naively describe with one boring scalar (hierarchy problem) problem and many free parameters to parametrize our ignorance (flavour puzzle)

  4. It seemed that n could not tell us anything about the vacuum because they could not feel it but they do…again in a extremely weak way

  5. The “other” helicity states • non-decoupling physics (scales at or below v): at least three new fundamental s=1/2 fields with no charge m= Weyl  no new scale M=0  L conserved Majorana  new scale M  0  L violated These could be furthermore coupled to a hidden sector: gauge interactions, more fermions, scalars… only linked to the visible sector through neutrino masses

  6. decoupling L-violating physics: M >> v • mixture: decoupling and not decoupling +… Weinberg

  7. why are n masses so small ? If M>> ln v the see-saw solution New scale solution M  v, ln =O(1): mn ~ v2/M  decoupling effect No new scale solution M ~ v: mn ~ ln2 v  Yukawa smallness (ifln~le  mn ~ O(1 eV) )

  8. what value of M is more natural ? M << v is natural because of L symmetry M>>v is not  hierarchy problem: Casas, Espinosa, Hidalgo

  9. Whether the new physics is associated to just a high scale or there is a hidden sector around the corner, its (strongest) link to the visible world is the n mass matrix: • Generically non-unitary PMNS matrix • Flavour structure in neutral currents • Mixing O(lnv/M) ~O(mn/ lnv)

  10. and not just a typical CKM… (|Ufi|,|Ufj|,|Ufk|) Maximal mixing in the 23 sector seems to imply redundancy: symmetry ?

  11. The fundamental questions: • what are the “other” helicity states: Weyl, Majorana or decoupling physics • what are the scales and dynamics involved in the interactions of these new fields? Is it a decoupling scale M >>v or is there a hidden sector at low scales • is there a L number conserved ? • are n relevant in cosmology and in the genesis of baryons ? The answers will provide a new perspective into the flavour puzzle and the hierarchy problem

  12. Solving the Flavour Puzzle Photomultiplier Einstein’s dream

  13. Our safest bet is to measure precisely the light n mass matrix: • overconstrain the PMNS matrix to see that it is not the whole story… • test symmetries: CP, CPT, maximal mixing…to give us a clueon the new interactions

  14. Standard 3n scenario The observables:

  15. The unknowns… q13a1, a2 d Hierarchy 0nbb m21, m23 0nbb, bb Cosmology sign(cosq23) Precise n oscillations

  16. The knowns… • q23 , q12, |Dm223|,Dm212 • Precise n oscillations • More precision and overconstraining the known parameters will also be important: • to resolve correlations with the unknown ones • search for new physics or symmetries: test of unitarity of the PMNS, establish maximal mixing

  17. The challenge… Measure small oscillation probabilities or measure large ones with high accuracy • There are only two mass splittings: |Dm223| >>Dm212 • Tunning En/L ~ Dm2ij we can enhance different terms even in • the same channel

  18. Sensitivity to unknows at En/L ~|Dm223| in matter Golden Silver e small parameters q13, D12/D23 vac/matter

  19. Sensitivity to knowns at En/L ~|Dm223| e small parameters q13, D12/D23

  20. Sensitivity at En/L ~Dm212 e q13

  21. Correlations and degeneracies At fixed En, L: Pnab(q13 ,d ) =Meas1 Pnab(q13 ,d ) =Meas2 Generically two solutions: true and intrinsic degeneracy Burguet-Castell, Gavela, Gomez-Cadenas,P.H.,Mena Including the discrete ambiguities eight-fold Pnab(q13 ,d ,D23, cos 2q23) =Meas1 Pnab(q13 ,d ,D23, cos 2q23) =Meas2 Barger,Marfatia, Whisnant Minakata, Nunokawa

  22. Dq13 d True d Fake p-d d p-d wrong sign wrong octant • Position of depend strongly on the E,L and channel • Fake do not depend on E and L • are the ones that increase the error on q13,d • In vacuum all are CP violating or all CP conserving: dfake=p-d

  23. Terrestrial precision n oscillation experiments

  24. Ultimate reactorsEn/L ~|Dm223| ? 90%CL < 1% syst • No sensitivity to the other unknowns • No dependence on d • If q13 large, great synergies with superbeams to resolve degeneracies Minakata, et al Anderson et al

  25. Reactors at E/L ~Dm212 SK-Gd can reach a sensitivity to Dm2122.8% (3s CL) Choubey,Petcov The sensitivity to sin2q12 can reach 2% (1sCL) in a reactor experiment tuned to the oscillation maximum SADOMinakata, Nunokawa, Teves, Zukanovich Funchal L=(50-70)km [8 x 10-5 eV2/Dm212] 4% syst. Stat: (~1700 events/y) 0.5 kton y (SADO) ≈1.4 kton y(KL)

  26. Superbeams Off-axis Use the conventional (more intense) beams: p  Target  K,pnm, % ne

  27. nm  ne T2K upgrade of K2K with a more intense beam and OA NOnA upgrade of MINOS with a better detector and OA 3s CL Sensitivity to q13 strongly depends on d in both cases and also onsign(D23) in NOnA

  28. Hierarchy at NOnA-I NOnA-I Only for sin22q13 > 0.04 and some values of d

  29. nm  nm The atmospheric parameters can be measured with high precision (per cent level): T2K-I: But the sensitivity to maximal mixing is not as good: q23=p/4 sin2 2q23 = 1-O(e2)

  30. Sensitivity to sin2q23 Minakata,Sonoyama Fernandez-Martinez et al For 42º < q23 < 50º the error on s223 remains O(10-20%) which is not much better than the present error!

  31. The new era (discovery) (roughly…depends on the actual value of the parameters) T2K-I seems to be a rather optimal setup for the next generation superbeam…should start taking data in 2008

  32. The new era (precision) (roughly…depends on the actual value of the parameters) T2K-I + reactors seem to be a rather optimal combination of setups for the next generation…

  33. Next-to-new era Superbeams: still room for improvement with a significant increase in power and/or detector: JPARC: 0.75  4MW, HyperK (Megaton!) NUMI: factor 4 with new Fermilab proton driver CERN-SPL: 4MW, Megaton Huge statistics, but systematics is critical ! T2K-II best sensitivity to q13, d, but not to hierarchy

  34. The race for the hierarchy NOnA: a second detector at the second oscillation maximum Nona proposal

  35. T2K-II:half of detector in Korea (2nd oscillation peak) 3s 2s Ishitsuka,Kajita,Minakata,Nunokawa

  36. Combination with atmospheric n T2K-II+atmospheric data Huber, Maltoni,Schwetz Comes for free! Also helps in resolving the q23 octant: 3s if |s232-0.5| > 0.1

  37. The known realm… • q23 ,|Dm223|: Maximal mixing can be established at % level only with a per mil sensitivity to sin22q23 T2K-I vs II T2K-II: e = 2 per mil - 1% Fernandez-Martinez et al

  38. The purists… • At accelerators we can also do electron (anti)-neutrino beams • above m threshold that are pure! • from m decay: • a magnetized detector indispensable! • from radioactive ions:

  39. A significant investment in accelerator infrastructure nFACT b-beam

  40. Very well-known fluxes

  41. Not so different starting point since the detector can be made more massive for the b-beam (it does not need magnetization) CERN-Canaries CERN-Frejus In both cases, there is an associated superbeam (SPL) that can be combined

  42. Higher gb-beam at longer baseline are possible and much better • more signal because of higher cross-sections • easier to measure the energy dependence • more significant matter effects CERN-Canfranc ? Burguet-Castell, et al

  43. Comparing b-beams Hierarchy, t23 Sin22q13 5x10-3 0.04

  44. Degeneracies at b-beam

  45. Ultimate anti-degeneracy machine nFACT &40KTon iron calorimeter 2800km (Golden)ne nm nFACT & 4Ton Emulsion 730km(Silver) ne nt SPL&Megaton Cerenkov (Bronce) 130km nm  ne The intrinsic and the q23 octant ambiguities are resolved (up to uncertainties) if the em and et are combined Donini, Meloni, Migliozzi

  46. q13 sensitivity down to 0.3º ! Hierarchy and octant solved for q13 > 1º-2º ! Overconstraining: em,ee,et,mt,me,mmfor n and n

  47. The new era (discovery) (roughly…depends on the actual value of the parameters) While T2K-I seems to be a rather optimal setup for the next generation superbeam, the “optimal” next-to-new generation experiment is still under investigation

  48. There are good ideas to reach the per cent sensitivity in the n mass matrix in the next 10-20 years The lepton flavour sector might turn out to be uninspiring…

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