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The Mu3e Experiment a New Search for Μ → Eee with Unprecedented Sensitivity

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The Mu3e Experiment a New Search for Μ → Eee with Unprecedented Sensitivity The Mu3e Experiment A new search for μ → eee with unprecedented sensitivity Kolloquium in Freiburg, November 29, 2017 André Schöning Universität Heidelberg Andre Schöning, Heidelberg (PI) 1 Kolloquium Freiburg, November 29, 2017 SM of Particle Physics SM Physics after the electroweak epoch is described by the SM Andre Schöning, Heidelberg (PI) 2 Kolloquium Freiburg, November 29, 2017 Questions in (Particle) Physics Sloan digital Sky Survey bullet cluster Matter Dark Matter Neither we understand the “observation” of ordinary matter nor the observation of dark matter. Must be understood! Andre Schöning, Heidelberg (PI) 3 Kolloquium Freiburg, November 29, 2017 Fermions in the Standard Model Higgs field Why 3 generations of fermions? Andre Schöning, Heidelberg (PI) 4 Kolloquium Freiburg, November 29, 2017 Fermion Masses in the SM TopTop QuarkQuark mm == 171171 GeV/cGeV/c2 Proton:Proton: mm ≈≈ 11 GeV/cGeV/c2 Elektron: Why Higgs couplings 2 m ≈ 0.5 MeV/c so different? Neutrinos:Neutrinos: mm ≈≈ 0.010.01 -- 0.10.1 eV/ceV/c2 Andre Schöning, Heidelberg (PI) 5 Kolloquium Freiburg, November 29, 2017 Fermion Masses in the SM y ~1 (within 1%) PLOT with YUKAWA t ? Andre Schöning, Heidelberg (PI) 6 Kolloquium Freiburg, November 29, 2017 Andre Schöning, Heidelberg (PI) Problems Unknowns Experimental → Observations → … → requires requires new (interactions)particles Fermion masses Fermion ( ofnature Fermion Observation Matter-antimatter → asymmetry universe in Physics Beyond the SM SM (BSM) the Beyond Physics hierarchy “problem”, hierarchy etc. ... no explanation yet no explanation require new particles or interactions beyond the SM beyond or interactions particles new require generations neutrinos Dark matter Dark Yukawa couplingsYukawa (Dirac or Majorana?) 7 ) Kolloquium Freiburg,November 29, 2017 CP-Violation Search Strategies High Energy Frontier LHC picture Direct searches of new resonances or interactions in the mass reach of colliders LHC, Future Circular Colliders, ... High Intensity and Precision Frontier LHC accelerator (Geneva) Indirect searches via precision measurements and searches for rare processes Electric Dipole Moments (EDM) Anomalous magnetic moments (g-2) Flavor Changing Neutral Current (FCNC) Charged Lepton Flavor Violation (cLFV) Muon g-2 @ Fermilab Andre Schöning, Heidelberg (PI) 8 Kolloquium Freiburg, November 29, 2017 Overview Standard Model and Lepton Physics (charged) Lepton Flavor Violation (cLFV) Mu3e experiment tracking concept detector systems Sensitivity studies Andre Schöning, Heidelberg (PI) 9 Kolloquium Freiburg, November 29, 2017 Flavor Physics f f H Z0, γ f f Higgs-Yukawa coupling Neutral Current f u c t νe νμ ντ W± (d )( s)(b) ( e )( μ )( τ ) f´ Charged Current Andre Schöning, Heidelberg (PI) 10 Kolloquium Freiburg, November 29, 2017 Flavor Mixing Matrices Quarks Leptons Cabibbo Kobayashi Maskawa (CKM) Pontecorvo Maki Nakagawa Sakata (PMNS) νe v v v ν1 d ' vud vus vub d e 1 e 2 e 3 ν = v v v ν s' = vcd vcs vcb s μ μ1 μ 2 μ 3 2 ( b' ) ( b ) ( ν ) v v v ν τ ( τ 1 τ 2 τ 3 ) v v v ( 3 ) ( td ts tb ) weak mass weak mass Q=-1/3 Q=+2/3 Q=0 Q=-1 Andre Schöning, Heidelberg (PI) 11 Kolloquium Freiburg, November 29, 2017 Flavor Changing Processes Flavor Changing Charged Currents are allowed. Flavor Changing Neutral Currents (FCNC) are forbidden! (on tree level) Quarks Leptons Q=+2/3 Q=-1 Q=-1/3 + * μ → e μ → νi (W ) γ Q=0 t → b t → c Andre Schöning, Heidelberg (PI) 12 Kolloquium Freiburg, November 29, 2017 Discovery of Neutrino Oscillations W W ν1 ν2 ν3 µ l 2 2 2 L P(να→νβ) = sin (2 Θ) sin (Δ mαβ ) E ν ● Neutrino Oscillations: solar neutrinos reactor neutrinos atmospheric neutrinos neutrino beams Andre Schöning, Heidelberg (PI) 13 Kolloquium Freiburg, November 29, 2017 FCNC via Quantum Loops μ → e via ν-oscillation W W ν1 ν2 ν3 µ e L 2 2 2 L P(να→νβ) = sin (2Θ) sin (Δ mαβ ) E ν Andre Schöning, Heidelberg (PI) 14 Kolloquium Freiburg, November 29, 2017 FCNC via Quantum Loops μ → e via ν-oscillation μ → e γ via loop W ν ν ν W ν 1 2 3 μ νe μ W e µ e γ L 2 2 2 L P(να→νβ) = sin (2Θ) sin (Δ mαβ ) E ν Andre Schöning, Heidelberg (PI) 15 Kolloquium Freiburg, November 29, 2017 FCNC via Quantum Loops μ → e via ν-oscillation μ → e γ via loop W ν ν ν W ν 1 2 3 μ νe μ W e µ e γ L 2 2 2 L 2 2 2 2 P(να→νβ) = sin (2Θ) sin (Δ mαβ ) B(μ→e γ) ∝ sin (2Θ) (Δ m /m ) E ν αβ W L→1/ mW Eν→ mW Andre Schöning, Heidelberg (PI) 16 Kolloquium Freiburg, November 29, 2017 Lepton Flavor Violation in the SM Higher Order! νμ νe μ W e LFV in generated from lepton mixing: γ 2 2 2 2 μ → e γ mν Δ mν BR(l → l γ) ∝ V (V )∗ i ∼ jk ∼ y 4 j k ∑i ij jk 2 2 ν ( M W ) ( M W ) ντ ν τ W μ μ γ τ → μ γ ντ νe τ W e γ τ → e γ Andre Schöning, Heidelberg (PI) 17 Kolloquium Freiburg, November 29, 2017 Lepton Flavor Violation in the SM Higher Order! νμ νe μ W e LFV in generated from lepton mixing: γ 2 2 2 2 μ → e γ mν Δ mν BR(l → l γ) ∝ V (V )∗ i ∼ jk ∼ y 4 j k ∑i ij jk 2 2 ν ( M W ) ( M W ) ντ ν τ W μ μ suppression factor for µ → e: ~ 10-50 γ → unobservable τ → μ γ → high sensitivity to new physics!!! ντ νe τ W e γ τ → e γ Andre Schöning, Heidelberg (PI) 18 Kolloquium Freiburg, November 29, 2017 Lepton Flavor Violation in the SM Higher Order! νμ νe μ W e LFV in generated from lepton mixing: γ 2 2 2 2 μ → e γ mν Δ mν BR(l → l γ) ∝ V (V )∗ i ∼ jk ∼ y 4 j k ∑i ij jk 2 2 ν ( M W ) ( M W ) ντ ν τ W μ μ suppression factor for µ → e: ~ 10-50 γ → unobservable τ → μ γ → high sensitivity to new physics!!! ντ νe τ W e 2 γ c.t. quark mixing: m2 c−u ~ −7 2 10 -10 M τ → e γ → FCNC in SM ~ 10 W Andre Schöning, Heidelberg (PI) 19 Kolloquium Freiburg, November 29, 2017 Lepton Flavor Conservation is an Accidental Symmetry! Andre Schöning, Heidelberg (PI) 20 Kolloquium Freiburg, November 29, 2017 History of LFV Decay experiments Mu3e I Mu3e II Andre Schöning, Heidelberg (PI) 21 Kolloquium Freiburg, November 29, 2017 LFV Muon Decays μ+ → e+ γ μ- N→ e- N μ+ → e+e+e- + + e + e Au e- μ- μ+ μ+ e+ γ e- MEG (PSI) SINDRUM II (PSI) SINDRUM (PSI) B(μ+ → e+γ) ≤ 4.2·10-13 (2016) B(μ Au → e Au) ≤ 7·10-13 (2006) B(μ+ → e+e+e-) ≤ 10-12 (1988) being upgraded Andre Schöning, Heidelberg (PI) 22 Kolloquium Freiburg, November 29, 2017 SM Loop Diagrams μ+ → e+ γ μ- N→ e- N μ+ → e+e+e- + + e + e Au e- μ- μ+ μ+ e+ γ e- SM: LFV loops Au (Δ m2)2 branching ratios suppressed by ν −50 ∝ 4 ≈ 10 mW Andre Schöning, Heidelberg (PI) 23 Kolloquium Freiburg, November 29, 2017 LFV Muon Decays and SUSY Loops μ+ → e+ γ μ- N→ e- N μ+ → e+e+e- + + e + e Au e- μ- μ+ μ+ e+ γ e- SUSY loops Au Most BSM models (e.g. SUSY) induce naturally LFV Andre Schöning, Heidelberg (PI) 24 Kolloquium Freiburg, November 29, 2017 LFV Muon Decays and SUSY Loops μ+ → e+ γ μ- N→ e- N μ+ → e+e+e- + + e + e Au e- μ- μ+ μ+ e+ γ e- SUSY loops Au enhanced by suppressed by extra vertex coherent conversion in with respect to μ+ → e+ γ nucleus field for Q2(γ*)~0 Andre Schöning, Heidelberg (PI) 25 Kolloquium Freiburg, November 29, 2017 LFV Tree Diagrams μ+ → e+ γ μ- N→ e- N μ+ → e+e+e- + + e + e Au e- μ- μ+ μ+ e+ γ e- q q LQ μ e not allowed e.g. Leptoquarks extra Z', LFV Higgs, etc. Additional BSM tree diagrams in μN → eN and μN → eee Andre Schöning, Heidelberg (PI) 26 Kolloquium Freiburg, November 29, 2017 first version (not published yet) Andre Schöning, Heidelberg (PI) 27 Kolloquium Freiburg, November 29, 2017 Search for μ+ → e+e+e- at PSI proton cyclotron world-highest Ip=2.4 mA @ 590 MeV intensity beam! project approved in Jan 2013 Aiming for a sensitivity of BR(μ → e e e ) ~ 2 ·10-15 (phase I) BR(μ → e e e ) < 10-16 (phase II) Andre Schöning, Heidelberg (PI) 28 Kolloquium Freiburg, November 29, 2017 How Big is 10-16 ? Number of grains of sand at all beaches in Germany ~ 1016 Find THE grain of sand which violates lepton flavor! Andre Schöning, Heidelberg (PI) 29 Kolloquium Freiburg, November 29, 2017 Backgrounds for Mu3e Irreducible BG: radiative decay with internal conversion (IC) - e ν e+ signal: B(μ+ → e+e+e-) - e e+ ν e+ B(μ+ → e+e+e- νν) = 3.4 ·10- 5 e+ E = m ∑i i μ p⃗ = 0 ∑i i Andre Schöning, Heidelberg (PI) 30 Kolloquium Freiburg, November 29, 2017 Backgrounds Irreducible BG: radiative decay with internal conversion (IC) - e ν e+ missing energy from two neutrinos R.M.Djilkibaev, steeply falling! R.V.Konoplich ν e+ PRD79 (2009) B(μ+ → e+e+e- νν) = 3.4 ·10- 5 very good momentum + total energy resolution required! Andre Schöning, Heidelberg (PI) 31 Kolloquium Freiburg, November 29, 2017 Accidental Backgrounds Overlays of two ordinary µ+ decays with a (fake) electron (e-) Electrons from: Bhabha scattering, photon conversion, mis-reconstruction Detector requirements: Vertex resolution Timing resolution Kinematic reconstruction Andre Schöning, Heidelberg (PI) 32 Kolloquium Freiburg, November 29, 2017 Tracking Resolution + Multiple Scattering Muon decay (m=105.6 MeV): → electrons in low momentum range p < 53 MeV/c limited hit Multiple scattering is dominant! resolution regime Need thin, fast and high resolution tracking detectors operated at high rate (>109 particles/s @ phase II) 1 Θ ∼ X / X MS P √ 0 mutiple scattering regime Andre Schöning, Heidelberg (PI) 33 Kolloquium Freiburg, November 29, 2017 Mu3e Design Concept Andre Schöning, Heidelberg (PI) 34 Kolloquium Freiburg, November 29, 2017 Momentum Resolution in MS Regime Standard spectrometer: multiple-scattering angle σ Θ p ∼ MS (linearised) P Ω precision requires large lever arm large bending angle Ω Andre Schöning, Heidelberg (PI) 35 Kolloquium Freiburg, November 29, 2017 Momentum Resolution in MS Regime “Half turn” spectrometer: σ p ∼ O(Θ2 ) P MS best precision for half turn tracks measure
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