Lepton Flavour Violation M. Hirsch mahirsch@ific.uv.es - PowerPoint PPT Presentation

Lepton Flavour Violation M. Hirsch mahirsch@ific.uv.es Astroparticle and High Energy Physics Group Instituto de Fisica Corpuscular - CSIC Universidad de Valencia Valencia - Spain IDPASC 2013, 07/05/2013 – p.1/42

Motivation IDPASC 2013, 07/05/2013 – p.2/42

Motivation Neutrinos oscillate! Confirmed by many experiments: SuperK, SNO, KamLAND, T2K, MINOS ... IDPASC 2013, 07/05/2013 – p.2/42

Motivation Neutrinos oscillate! Confirmed by many experiments: SuperK, SNO, KamLAND, T2K, MINOS ... Charged leptons? ... only upper limits! IDPASC 2013, 07/05/2013 – p.2/42

Outline I . Neutrinos - experiment II . Short aside on neutrino masss III . Charged lepton flavour violation IV . Conclusions IDPASC 2013, 07/05/2013 – p.3/42

I . Neutrinos - experiment IDPASC 2013, 07/05/2013 – p.4/42

Neutrino oscillations Consider simplified two generation example: 0 1 0 1 0 1 @ ν e @ cos θ sin θ @ ν 1 A = A · A ν µ − sin θ cos θ ν 2 x ) = (0 ,� A neutrino created as | ν e > at x = ( t, � 0) with energy E will evolve as: | ν e ( x ) > = e ip 1 x | ν 1 > + e ip 2 x | ν 2 > The probability of ν µ appearance at a distance � x = (0 , 0 , L ) is P ( ν e → ν µ ) = | < ν µ | ν ( L ) > | 2 ≃ sin 2 (2 θ ) sin 2 ( ∆ m 2 12 L ) 4 E ⇒ oscillations in vacuum IDPASC 2013, 07/05/2013 – p.5/42

3-generation mixing For 3 generations of leptons, 2 independent ∆ m 2 ij , mixing has 3 θ ij : 0 1 s 13 e − iδ c 12 c 13 s 12 c 13 B C B C − s 12 c 23 − c 12 s 23 s 13 e iδ c 12 c 23 − s 12 s 23 s 13 e iδ U = A · P s 23 c 13 @ s 12 s 23 − c 12 c 23 s 13 e iδ − c 12 s 23 − s 12 c 23 s 13 e iδ c 23 c 13 0 1 0 1 0 1 s 13 e − iδ 1 0 0 c 13 0 c 12 s 12 0 B C B C B C B C B C B C = A · A · A · P 0 c 23 s 23 0 1 0 − s 12 c 12 0 @ @ @ − s 13 e iδ 0 − s 23 c 23 0 c 13 0 0 1 IDPASC 2013, 07/05/2013 – p.6/42

3-generation mixing For 3 generations of leptons, 2 independent ∆ m 2 ij , mixing has 3 θ ij : 0 1 s 13 e − iδ c 12 c 13 s 12 c 13 B C B C − s 12 c 23 − c 12 s 23 s 13 e iδ c 12 c 23 − s 12 s 23 s 13 e iδ U = A · P s 23 c 13 @ s 12 s 23 − c 12 c 23 s 13 e iδ − c 12 s 23 − s 12 c 23 s 13 e iδ c 23 c 13 0 1 0 1 0 1 s 13 e − iδ 1 0 0 c 13 0 c 12 s 12 0 B C B C B C B C B C B C = A · A · A · P 0 c 23 s 23 0 1 0 − s 12 c 12 0 @ @ @ − s 13 e iδ 0 − s 23 c 23 0 c 13 0 0 1 atmospheric reactor & solar & and long-baseline long-baseline reactor experiments experiments experiments IDPASC 2013, 07/05/2013 – p.6/42

3-generation mixing For 3 generations of leptons, 2 independent ∆ m 2 ij , mixing has 3 θ ij : 0 1 s 13 e − iδ c 12 c 13 s 12 c 13 B C B C − s 12 c 23 − c 12 s 23 s 13 e iδ c 12 c 23 − s 12 s 23 s 13 e iδ U = A · P s 23 c 13 @ s 12 s 23 − c 12 c 23 s 13 e iδ − c 12 s 23 − s 12 c 23 s 13 e iδ c 23 c 13 0 1 0 1 0 1 s 13 e − iδ 1 0 0 c 13 0 c 12 s 12 0 B C B C B C B C B C B C = A · A · A · P 0 c 23 s 23 0 1 0 − s 12 c 12 0 @ @ @ − s 13 e iδ 0 − s 23 c 23 0 c 13 0 0 1 atmospheric reactor & solar & and long-baseline long-baseline reactor experiments experiments experiments ⇒ P - diagonal matrix of Majorana phases observable only in ∆ L = 2 processes IDPASC 2013, 07/05/2013 – p.6/42

Atmospheric oscillations SuperK, 1998: cos θ IDPASC 2013, 07/05/2013 – p.7/42

Atmospheric oscillations SuperK, 1998: angular dependent deficit of ν µ ⇒ ν µ oscillate! cos θ IDPASC 2013, 07/05/2013 – p.7/42

Atmospheric oscillations SuperK, 1998: angular dependent deficit of ν µ ⇒ ν µ oscillate! cos θ Super-K, 2004: L/E dependence favours oscillation solution! IDPASC 2013, 07/05/2013 – p.7/42

Atmospheric oscillations Fig from: Forero, Tortola & Valle, 2012 LBL - long baseline experiments (mostly MINOS) ATM - atmospheric neutrino data, Super-Kamiokande Atm = (2 . 2 − 2 . 74) × 10 − 3 eV 2 ∆ m 2 sin 2 θ Atm = (0 . 36 − 0 . 68) - consistent with maximal mixing IDPASC 2013, 07/05/2013 – p.8/42

Solar oscillations SNO, 2000 & 2002: IDPASC 2013, 07/05/2013 – p.9/42

Solar oscillations SNO, 2000 & 2002: 8 ) -1 SNO SNO φ φ s ES CC 7 -2 cm 6 6 (10 5 τ µ SNO φ 4 φ NC φ 3 SSM 2 1 0 0 1 2 3 4 5 6 6 -2 -1 (10 cm s ) φ e ⇒ Measurement of NC confirms flavour conversion of ν ⊙ ⇒ Oscillations as explanation likely, but not proven IDPASC 2013, 07/05/2013 – p.9/42

Solar oscillations KamLAND 2002, & 2008: IDPASC 2013, 07/05/2013 – p.10/42

Solar oscillations KamLAND 2002, & 2008: ⇒ Measurement of LE proves neutrino oscillations ⇒ LA-MSW Oscillations as only explanation for ν ⊙ IDPASC 2013, 07/05/2013 – p.10/42

Solar neutrinos - fit Fig from: Forero, Tortola & Valle, 2012 KamLAND - reactor data solar - SNO, SuperK, GALLEX, CL, etc ... global - combination of all data ⊙ = (7 . 27 − 8 . 01) × 10 − 5 eV 2 ∆ m 2 sin 2 θ ⊙ = (0 . 27 − 0 . 37) - consistent with 1/3. IDPASC 2013, 07/05/2013 – p.11/42

Reactor neutrinos IDPASC 2013, 07/05/2013 – p.12/42

Reactor neutrinos PRL 108 (2012) [arXiv:1112.6353] sin 2 (2 θ 13 ) = 0 . 086 ± 0 . 041( stat ) ± (0 . 030)( syst ) Non-zero @ 2 σ c.l. PRL 108 (2012) [arXiv:1203.1669] sin 2 (2 θ 13 ) = 0 . 092 ± 0 . 016( stat ) ± (0 . 005)( syst ) Non-zero @ 5.2 σ c.l. PRL 108 (2012) [arXiv:1204.0626] sin 2 (2 θ 13 ) = 0 . 113 ± 0 . 013( stat ) ± (0 . 019)( syst ) Non-zero @ 4.9 σ c.l. IDPASC 2013, 07/05/2013 – p.13/42

Don’t know ν ’s Open questions: Which hierarchy: Normal or inverted? What is the absolute neutrino mass scale? Is there CP violation in the lepton sector? IDPASC 2013, 07/05/2013 – p.14/42

Don’t know ν ’s Open questions: Which hierarchy: Normal or inverted? What is the absolute neutrino mass scale? Is there CP violation in the lepton sector? Is lepton number violated??? IDPASC 2013, 07/05/2013 – p.14/42

Absolute mass scale Tritium decay end point searches: KATRIN: qP m β m β i | U ei | 2 m 2 ν = i ≤ 2 . 2 eV ν ≤ 0 . 2 eV 2017 (??) Double beta decay: Majorana neutrino! = P m ββ i U 2 ei m i ≤ (0 . 25 − 0 . 5) eV ν KamLAND-Zen & EXO-200 depending on data set! Cosmology (CMB Planck + LSS + · · · ): Planck only: P P ⇐ i m ν i ≤ 1 . 0 eV i m ν i ≤ (0 . 3 − 1 . 0) eV Planck+BAO: P ⇒ Recall for hierarchical neutrinos: i m ν i ≤ 0 . 3 eV q q ∆ m 2 ∆ m 2 Atm ∼ 50 meV and ⊙ ∼ 9 meV IDPASC 2013, 07/05/2013 – p.15/42

Future experiments Currently running / under construction / comissioning: EXO-200 GERDA-I/II CUORE KamLAND-Zen A Z 136 Xe 76 Ge 130 Te 136 Xe Mass 160 kg 35 kg 200 kg 400 kg Method liquid TPC ionization bolometer scint. Location WIPP LNGS LNGS Kamioka Starts (?) 2010 2010 2012 2011 3 × 10 25 - 1.5 × 10 26 ∗ T 0 νββ 6.4 × 10 25 (2-6.5) × 10 26 6 × 10 26 (est.) 1 / 2 � m ν � ( est. ) eV 0.03-0.05 ∗ 0.02-0.06 ∗∗ 0.19 0.28-0.12 Assumptions: ∗ - Background level 10 − 2 - 10 − 3 e/ (y · kg · keV) , i.e. improvement ≃ 20 − 200 ∗∗ - Phase II with 1 ton: 0 . 020 @ 5 years, BG with MC simulation IDPASC 2013, 07/05/2013 – p.16/42

II . Short aside on neutrino masss or Why is m ν so small? IDPASC 2013, 07/05/2013 – p.17/42

Dirac M ν If Lepton Number is Conserved: L = L SM + Y ν ij L i Hν R,j Experimental data requires: | Y ν | ≃ 10 − 12 Fit to all oscillation data possible and simple, but ... ⇒ Any “predictions” of this scenario??? IDPASC 2013, 07/05/2013 – p.18/42

Dirac M ν If Lepton Number is Conserved: L = L SM + Y ν ij L i Hν R,j Experimental data requires: | Y ν | ≃ 10 − 12 Fit to all oscillation data possible and simple, but ... ⇒ Any “predictions” of this scenario??? (i) No double beta decay (ii) No charged lepton flavour violation IDPASC 2013, 07/05/2013 – p.18/42

Majorana M ν If Lepton Number is Violated: � H � � H � Weinberg, 1979 1 m ν = M LNV ( LH )( LH ) ( M LNV ) − 1 ν L ν L Which scale? Many realizations: M LNV ≃ M GUT (i) Seesaw mechanism: Type-I, Type-II, Type-III, Inverse seesaw, etc ... or (ii) Radiative models: Zee, Babu, LQs ... (iii) SUSY neutrino masses: R p / M LNV ≃ M EW (iv) · · · IDPASC 2013, 07/05/2013 – p.19/42

Seesaw mechanism � H � � H � Seesaw type-I, right-handed neutrinos: m 1 / 2 ≃ ( − Y 2 ν v 2 ν R , M M ) M M ⇒ For M M ∼ 10 15 GeV h ν ∼ 1 ν L ν L � H � � H � Seesaw type-II, scalar triplet: v 2 m ν ≃ Y T � ∆ 0 L � ≃ Y T ∆ m ∆ ⇒ For M T ∼ 10 15 GeV Y T ∼ 1 ν L ν L � H � � H � Type-III: Replace ν R by Σ = (Σ + , Σ 0 , Σ − ) : Σ 0 m 1 / 2 ≃ ( − Y 2 Σ v 2 , M Σ ) M Σ ⇒ Similar to type-I, but Σ = (Σ + , Σ 0 , Σ − ) ν L ν L IDPASC 2013, 07/05/2013 – p.20/42