Neutrino Mass and Lepton Number Violation - Björn Lehnert - CERN Indico
←
→
Page content transcription
If your browser does not render page correctly, please read the page content below
Neutrino Mass and Lepton Number Violation = ICHEP 2020, Björn Lehnert August 6th 2020 bjoernlehnert@lbl.gov Prague, Czech Republic (online)
Scope of this talk Sources of information: • Neutrino masses from • Beta decay • Cosmology http://ichep2020.org • Double beta decay • Lepton number violation https://conferences.fnal.gov/nu2020/ (video recordings) Disclaimer: Part of & Experimental point of view Mini-Workshop series https://indico.fnal.gov/category/1172/ Wide range to cover for 25 min (video recordings) Apologies if your favorite topic / experiment is not covered !2
28/7 Mariam Tórtola: Neutrino Parameters Global fits to neutrino masses and mixings ∑ Neutrino mixing: PMNS (Pontecorvo-Maki-Nakagawa-Sakata) | νflavor > = U* αi ⋅ | νmass > i 1 0 0 cΘ13 0 sΘ13 ⋅ e −iδ cΘ12 sΘ12 0 1 0 0 Uαi = 0 cΘ23 sΘ23 0 1 0 −sΘ12 cΘ12 0 0 e −iα/2 0 0 −sΘ23 cΘ23 −sΘ13 ⋅ e −iδ 0 cΘ13 0 0 1 0 0 e −iβ/2 Neutrino masses: 2 Δm12 ≈ 8 meV Mass2 2 Δm23 ≈ 50 meV ??? absolute mass scale unknown normal Ordering inverted Ordering 2 2 • Precision measurements with oscillation: Θ12, Θ13, Θ23, Δm12, Δm23 iδ 2 • Upcoming oscillation measurements (subdominant matter effects): CP phase e , ordering sign(Δm23) • Not accessible with oscillations: absolute mass scale, Dirac (ν ≠ ν̄) or Majorana (ν = ν̄, α, β) Can be measured in neutrino mass and double beta decay experiments !3
Different Neutrino Mass Observables β-decay (kinematic) model independent mβ mΣ cosmology model dependent mass eigenstate • ΛCDM mixing ∑ mi2 | Uei |2 mΣ = mi ∑ mβ = i i m1 m m3 2 double beta decay mββ miUei2 | ∑ model dependent mββ = | • lepton number violation • light Majorana neutrino exchange i !4
Different Neutrino Mass Observables β-decay (kinematic) model independent mβ mΣ cosmology model dependent mass eigenstate • ΛCDM mixing ∑ mi2 | Uei |2 mΣ = mi ∑ mβ = i i m1 m m3 2 double beta decay mββ miUei2 | ∑ model dependent mββ = | • lepton number violation • light Majorana neutrino exchange i !5
Beta Decay Measurements Precision spectroscopy Experimental signature: of β-decays • Spectral distortion at endpoint 00 x50 Experimental Challenges: Observable m2β: • High resolution • Appears in β-spectrum: • Low background • Convenient isotope: half-life, Q-value 3H (12 yr, 18.6 keV), 163Ho (4600 yr, 2.8 keV) Other kinematic limits [pdg]: • No model dependence (only kinematics) •SN1987: m e < 5.8 eV • -decay: m < 190 keV • -decay: m < 18.2 MeV !6
30/7 Alexey Lokhov The KATRIN Experiment KATRIN experiment: first neutrino mass result and future prospects 70 m beam line rear windowless T2 removal and main spectrometer pixel section tritium source e- transport as high pass filter Si det electric molecular potential tritium T2 1011 Bq resolution: ~1 eV background: 0.29 cts/s
KATRIN data with 1 error bars 50 30/7 Alexey Lokhov Count rate (cps) Fit result KATRIN - First Results 10 1 KATRIN experiment: first neutrino mass result and future prospects Dataset: 33 d (22% column density) 10 0 KATRIN data with 1 error bars 50 Count rate (cps) Fit result 10 1 PRL 123, 221802 (2019) Best fit: m = 2 1.0+0.9 eV 2 AAACE3icbVDLSgMxFM3UV62vqks3wSKI4jBTBHUhFN24rGAf0MeQSW/b0GRmSDJCGcZvcOOvuHGhiFs37vwb08dCWw9cODnnXnLv8SPOlHacbyuzsLi0vJJdza2tb2xu5bd3qiqMJYUKDXko6z5RwFkAFc00h3okgQifQ80fXI/82j1IxcLgTg8jaAnSC1iXUaKN5OWPhNf0QZN2EV/iE9d22smxY1+kXmIebvqQNKXAUG0X05yXLzi2MwaeJ+6UFNAUZS//1eyENBYQaMqJUg3XiXQrIVIzyiHNNWMFEaED0oOGoQERoFrJ+KYUHxilg7uhNBVoPFZ/TyREKDUUvukURPfVrDcS//Mase6etxIWRLGGgE4+6sYc6xCPAsIdJoFqPjSEUMnMrpj2iSRUmxhHIbizJ8+TatF2Hdu9PS2UrqZxZNEe2keHyEVnqIRuUBlVEEWP6Bm9ojfryXqx3q2PSWvGms7soj+wPn8AJL2bLg== 1.1 -40 -30 -20 mβ2 -10 0 10 20 30 40 Time (h) Residuals ( ) • 19% probability to get same or smaller value 2 0 normalization Stat. Stat. + syst. background 10 endpoint 0 Limit setting: -2 • Lokhov-Tkachov: mβ < 1.1 eV (90% CL) -40 -40 -30 -30 -20 -20 -10 -10 00 1010 2020 3030 4040 Residuals ( ) identical to sensitivity 40 2 Stat. Stat. + syst. • Feldman-Cousins: mβ < 0.8 eV (90% CL) 20 0 • Bayesian: mβ < 0.9 eV (90% CI) 0-2 -40 -40 -30 -30 -20 -20 -10 00 1010 2020 3030 4040 flat prior m2β -10 >0 Retarding energy - 18574 (eV) 40 Time (h) 20 0 -40 -30 -20 -10 0 10 20 30 40 Retarding energy - 18574 (eV) Mainz m < 2 eV First KATRIN dataset: β Troitsk KATRIN • Statistics improved by x2 • Systematic improved by x6 !8
30/7 Alexey Lokhov KATRIN - Outlook KATRIN experiment: first neutrino mass result and future prospects Uncertainty budget: • Dominated by statistics • Largest systematic from background Sensitivity goal: • 3 yr data (5 yr operation) • 0.2 eV (90% CL) • 0.35 eV (3 ) More data recorded: Background reduction: Other analyses: 0.29 → 0.15 cts / s eV and keV sterile neutrinos • spectrometer bake-out • alternative operating mode (this dataset) (finished last week) !9
Nu2020: Noah Oblath Project 8 Project 8 [link] Idea: measure frequency very precisely Ultimate plan: CRES (Cyclotron Radiation Emission Use atomic tritium Spectroscopy) of β-decay electrons to reduce molecular final states atomic molecular Status: First measurement of T2 spectrum with preliminary analysis mβ (meV) Projected sensitivity: !10
Nu2020: Maurits Haverkort ECHo and HOLMES Mass measurements with Ho-163 [link] Electron capture in 163Ho: Technology: • T1/2 = 4570 yr • pixelated cryogenic bolometers (
Different Neutrino Mass Observables β-decay (kinematic) model independent mβ mΣ cosmology model dependent mass eigenstate • ΛCDM mixing ∑ mi2 | Uei |2 mΣ = mi ∑ mβ = i i m1 m m3 2 double beta decay mββ miUei2 | ∑ model dependent mββ = | • lepton number violation • light Majorana neutrino exchange i !12
Cosmological mΣ signatures Nu2020: Lloyd Knox Cosmological probes of standard neutrino scenarios [link] Matter distributions influenced by mΣ Cosmic microwave background (CMB) Heavy neutrinos wash out gravitational wells influenced by mΣ and disfavor small structures CMB anisotropies power spectrum of matter distribution [Y. Wong] CMB lensing • Visible effect of m∑ • No effect from flavor larger smaller !13
Outlook for cosmology Current limits: Future limits: • mΣ < 120 meV (95% CL) Planck + BAO [arXiv:1807.06209v2] • mΣ ~ 20 meV (CMB-S4 + BAO) • tightest bound on neutrino mass • mass ordering with 2-4 σ Project 8 goal Future experiments: CMB: LiteBIRD, Simons Obs., CMB-S4, BICEP Array, … Surveys: EUCLID, ROMAN, DESI, PFS, VERA RUBIN, … 4/8 David P. Kirkby CMB, cosmology, other astroparticle physics [arXiv:1907.04473] Distant future: CνB measurement with PTOLEMY 29/7 Stefano Gariazzo Neutrino physics with the PTOLEMY project Keep in mind: • mΣ model dependent (ΛCDM, systematics, parameter correlations) 29/7 Marcello Messina • Complementary with β-decay measurements The PTOLEMY experiment to look at the first second of the Universe • Tension between mβ and mΣ would point to new physics !14
Different Neutrino Mass Observables β-decay (kinematic) model independent mβ mΣ cosmology model dependent mass eigenstate • ΛCDM mixing ∑ mi2 | Uei |2 mΣ = mi ∑ mβ = i i m1 m m3 2 double beta decay mββ miUei2 | ∑ model dependent mββ = | • lepton number violation • light Majorana neutrino exchange i !15
Neutrinoless Double Beta Decay & Lepton Number Violation Double beta decays: Experimental signature: • Peak search at Q-value 2⌫ : (Z, A) ! (Z + 2, A) + 2e + 2¯ ⌫e • Measure half-life of 0νββ decay 0⌫ : (Z, A) ! (Z + 2, A) + 2e Lepton number violation: ΔL = 2 Majorna neutrinos observed in 11 nuclei to be observed produced L prod. asymmetry B prod. equally by heavy observed B ≠ 0 Why looking for lepton number violation? ν decay B-L = const. L=0, B=0 • Lightness of neutrinos could be explained by see-saw mechanism(s) • Predicts heavy Majorana neutrinos 109+1 109 matter antimatter • Neutrino decay generates lepton number in early Universe • Baryogenesis through Leptogenesis matter - antimatter asymmetry !16
Standard Mechanism: Light Majorana Neutrino Exchange (T1/2) −1 0ν 0ν 2 2 = G ⋅ | M | ⋅ | mββ | phase nuclear matrix effective Majorana measured space element neutrino mass half-life factor experiment atomic physics nuclear physics particle physics Mass of a virtual electron neutrino propagator: | mββ | = m1 | Uei2 | + m2 | Ue2 2 | e i(α2−α1) + m3 | Ue3 2 | e −i(α1+2δ) Im inverted ordering mee m (eV) 2 | ββ ee Re = G0⌫ · |M0⌫ |2 · |m δ) +2 m 2 | Ue2 Im −i (α 1 normal ordering 2 | e = G2⌫ · |M2⌫ |2 e3 |U |2 e Advances in High Energy m3 i(α 2−α1 Physics Vol 2016, 2162659 mee ) m1 | Ue1 |2 Re !17
Double Beta Decay Experiments Experimental challenges: Many possible DBD isotopes: • Large exposure: tonne-scale (> 1028 nucl. x yr) • 35 isotopes β-β- • Low background: < 1 cts / tonne / yr / ROI • 34 isotopes ECEC, β+EC, β+β+ Most promising technologies (next slides): • Liquid scintillators • Xenon TPCs • Cryogenic bolometers • High Purity Germanium (HPGe) Many more experiments: CANDLES, CDEX, SuperNEMO, SELENA, NuDEx, ZICOS, AMoRE, C0BRA, Theia, PandaX, AXEL, R2D2, … Secondary signatures: • 2νββ decay Poster: Malak Hoballah: 30/7 Anselmo Meregaglia: • Excited state transitions Calibration status of the Preliminary results of the R2D2 project: a new • Spectral shapes SuperNEMO calorimeter neutrinoless double beta decay experiment sample Comprehensive comparison of experiments: ββ use of small setups Nu2020: Jason Detwiler e.g. low background ɣ Future Neutrinoless Double γ - spectroscopy HPGe Beta Decay Experiments [link] !18
Nu2020: Christopher Grant Liquid Scintillators: KamLAND-ZEN (136Xe), SNO+ (130Te) KamLAND-ZEN and SNO+ [link] Advantage LS: Large target mass, KamLAND-ZEN self-shielding, multi-purpose detectors 1 kt LS, ~1900 PMTs (~34% coverage) 91% enriched 136Xe KL-Zen 400 KamLAND 2 Zen (future) KL-Zen 800 • x5 light collection, • 2011-2015 • since 2019 scintillating balloon, • 350 kg Xe mini-ballon • 745 kg Xe new electronics • T1/2 > 1.1 x 1026 yr • mββ < 61 - 165 meV with Xe • T1/2 ~ 5 x 1026 yr (goal) • 1 tonne Xe • T1/2 ~ 2 x 1027 yr (goal) PRL 117, 082503 (2016) @Kamioka, Japan SNO+ Status July: filling with liquid scintillator 780 t LS, ~9300 PMTs (~50% coverage) natTe (34% 130Te) Sensitivity for natTe loading: • 0.5%: T1/2 ~ 2 x 1026 yr (goal) • 1.5%: T1/2 ~ 4 x 1026 yr (goal) • 2.5%: T1/2 ~ 1 x 1027 yr (goal) (0.5% loading ~1.3 t 130Te) @SNOLAB, Canada !19
Nu2020: J J Gomez-Cadenas Xe TPCs: nEXO, NEXT, Darwin (136Xe) Xe-136 Experiments, present and future [link] Advantage Xe TPC: LXe TPC single phase: EXO-200, nEXO • signal: charge + scintillation light Self-shielding, Particle ID • enriched 136Xe (90%) EXO-200 nEXO • 200 kg enrXe • 5 tonne enrXe • T1/2 > 3.5 x 1025 yr (90% CL) • T1/2 ~ 1028 yr (goal) • mββ < 93 - 286 meV • mββ ~ 6 - 18 meV (goal) EXO-200 TPC @WIPP, USA PRL 123, 161802 (2019) arXiv:1805.11142 @ SNOLAB HPXeEL TPC: NEXT Future potential: external Ba measurement barium tagging Experimental plans: NEXT-White (5 kg) NEXT-100 (100 kg) internal Ba NEXT-HD (1 t, ~1027 yr) measurement NEXT-BOLD (~1028 yr) NEXT-100 TPC @Canfranc, Spain ββ topology ID arXiv:1906.01743 LXe TPC dual phase: Dark Matter detectors • Xe WIMP detectors also sensitivity to 0νββ - decay • Discovery of 2νECEC in 124Xe (Xenon-1t) Nature 568, 532 (2019) DARWIN: 29/7 Adriano Di Giovanni: • 50 tonne natXe (9%), The DARWIN experiment: the ultimate detector for direct • T1/2 ~ 2.4 x 1027 yr (goal) Nature 569, 203 (2019) dark matter search. arXiv:2003.13407 !20
Nu2020: Thomas O'Donnell Bolometers: CUORE (130Te), CUPID (100Mo) CUORE Results and the CUPID Project [link] Advantage bolometers: Good resolution, segmented, flexible isotope @LNGS, Italy 30/7 Andrea Giachero: New results from the CUORE CUORE experiment CUPID • natTeO2 crystals • Li2100MoO4 crystals (enriched) • Heat • Heat + light • T1/2 > 3.2 x 1025 yr (90% CI) similar mass but major • T1/2 ~ 1027 yr (goal) • mββ < 75 - 350 meV background reduction • mββ ~ 10 - 20 meV (goal) PRL 124, 122501 (2020) 30/7 Davide Chiesa: Double beta decay results New results CUORE: from the CUPID-0 experiment • 130 Te 2νββ measurement • 130Te 0ν and 2ν excited state limit New results CUPID-Mo: New results CUPID-0: • 100Mo 0νββ half-life limit • 82Se 0νββ half-life limit T1/2 > 1.4 x 1024 yr (90% CI) T1/2 > 3.5 x 1024 yr (90% CI) mββ < 310 - 540 meV mββ < 311 - 638 meV • 100Mo 2νββ half-life measurement • 82Se 2νββ half-life measurement !21
Nu2020: Yoann Kermaidic HPGe Detectors: GERDA, MJD, LEGEND (76Ge) GERDA, Majorana and LEGEND - towards a background-free ton-scale Ge76 experiment [link] Advantage HPGe: 30/7 Konstantin Gusev: Best resolution, segmented Results of the GERDA Phase II experiment • T1/2 > 1.8 x 1026 yr (90% CL) GERDA • mββ < 80 - 182 meV Majorana Demonstrator • HPGe array in liquid argon • HPGe array in vacuum cryostat • Lowest background in ROI • Best energy resolution in DBD • World best half-life limit • Leading limit on excited states @SURF, USA @LNGS, Italy combining technology + new concepts 29/7 Wenqin Xu: 30/7 Luis Manzanillas: Status and Recent Results of the Usage of PEN as self-vetoing structural material in low background experiments LEGEND-200 MAJORANA DEMONSTRATOR • Under construction in Poster: Clay Barton: GERDA infrastructure Neutron Background Simulations for • T1/2 ~ 1027 yr (goal) LEGEND-1000 in a Geant4-based Framework LEGEND-1000 • Tonne scale • Underground argon • T1/2 ~ 1028 yr (goal) • mββ ~ 10 - 20 meV (goal) PEN: new scintillating structural material !22
Future of Double Beta Decay What if oscillation experiments determine the normal ordering? • Most probable parameter space still accessible (assuming flat priors) M. Agostini, G. Benato, J. Detwiler: PRD 96, 053001 (2017) normal ordering inverted ordering next generation goal current β-decay current β-decay cosmology cosmology Bayesian sampling assuming flat priors for Majorana phases current current Nuclear Matrix Elements: (T1/2) −1 0ν 0ν 2 2 uncertainties (x3) = G ⋅ | M | ⋅ | mββ | nuclear matrix element Nu2020: Javier Menéndez nuclear physics Double beta decay matrix elements [link] • Need nuclear models: Shell model, QRPA, IBM, … • Recent advances with EFT • Informed by 2νββ, excited states, spectral shapes isotopes !23
What if we discover 0νββ decay? • Lepton number violation exists 2 (T1/2) −1 0ν 0ν ∑ =G ⋅ Mi ⋅ ηi • Neutrinos are Majorana particles (Schechter-Valle theorem) mech i different dominant LNV mechanism? coherent sum of multiple LNV mechanisms? light Majorana Higgs right handed BUT: What is the LNV mechanism? SUSY particle neutrinos triplet currents • Disentangle mechanism with observation in multiple isotopes • Strong motivation for different 0νββ decay experiments / isotopes Signatures in particle colliders: LNV with rare Kaon decay: + + • Same sign di-lepton di-jet searches • K → π νν 0 • KL → π νν 31/7 Kåre Fridell: Implications of Rare Kaon Decays on Lepton Number Violating Interactions [Un-ki Yang Nu2020] !24
Global Picture & Conclusion Neutrino masses 1 year ago: [from Eligio Lisi, TAUP19] Neutrino masses measured in three observables: • Beta Decay (recent results from KATRIN) mβ < 1.1eV • Cosmology (results from Planck + BAO) mΣ < 120 meV • Double beta decay (new results from GERDA) mββ < 60 − 130 meV Lepton number violation tested: • Double beta decay experiments • Collider experiments (assuming no sterile neutrinos) !25
Global Picture & Conclusion Neutrino masses 1 year ago: [from Eligio Lisi, TAUP19] KATRIN 2019 Neutrino masses measured in three observables: • Beta Decay (recent results from KATRIN) mβ < 1.1eV • Cosmology (results from Planck + BAO) mΣ < 120 meV • Double beta decay (new results from GERDA) mββ < 60 − 170 meV Lepton number violation tested: • Double beta decay experiments • Collider experiments KATRIN 2019 (assuming no sterile neutrinos) !26
Global Picture & Conclusion Neutrino masses 1 year ago: [from Eligio Lisi, TAUP19] KATRIN 2019 Neutrino masses measured in three observables: • Beta Decay (recent results from KATRIN) mβ < 1.1eV • Cosmology (results from Planck + BAO) mΣ < 120 meV • Double beta decay (new results from GERDA) mββ < 60 − 170 meV Lepton number violation tested: • Double beta decay experiments • Collider experiments Thank you for your attention! KATRIN 2019 (assuming no sterile neutrinos) !27
Backup
Nu2020: Jason Detwiler Comparing DBD Experiments Future Neutrinoless Double Beta Decay Experiments [link] !29
Nu2020: Jason Detwiler Comparing DBD Experiments Future Neutrinoless Double Beta Decay Experiments [link] !30
You can also read
