High Luminosity/High Energy LHC perspectives on Taus Emilie - PowerPoint PPT Presentation

High Luminosity/High Energy LHC perspectives on Taus Emilie Passemar Indiana University/Jefferson Laboratory HL/HE LHC meeting Fermilab, April 5, 2018 Emilie Passemar

Outline : 1. Introduction and Motivation: 2. Lepton Flavour Violation 3. Other interesting topics with tau decays 4. Conclusion and outlook Emilie Passemar

1.1 Quest for New Physics • New era in particle physics : (unexpected) success of the Standard Model : a successful theory of microscopic phenomena with no intrinsic energy limitation • Where do we look? Everywhere! search for New Physics with broad search strategy given lack of clear indications on the SM-EFT boundaries ( both in energies and effective couplings ) • Hint from B physics anomalies? b → c charged currents: τ vs. light leptons (µ, e) [R(D), R(D*)] 3 Emilie Passemar Emilie Passemar

1.1 Quest for New Physics • New era in particle physics : (unexpected) success of the Standard Model : a successful theory of microscopic phenomena with no intrinsic energy limitation • Where do we look? Everywhere! search for New Physics with broad search strategy given lack of clear indications on the SM-EFT boundaries ( both in energies and effective couplings ) • Hint from B physics anomalies? b → c charged currents: τ vs. light leptons (µ, e) [R(D), R(D*)] b L c L b L c L NP W τ L ν L ν L τ L , ℓ L Key unique role of Tau physics 4 Emilie Passemar Emilie Passemar

1.2 τ lepton as a unique probe of new physics • In the quest of New Physics, can be sensitive to very high scale: E sdsd – Kaon physics: Λ � 10 5 TeV ⇒ [ ε K ] Λ 2 Λ NP τ µ – Tau Leptons: µeff Λ � 10 3 TeV 4 2 ⇒ [ τ → µ γ ] Λ 2 • At low energy: lots of experiments e.g., BaBar , Belle , BESIII, LHCb important improvements on measurements and bounds obtained and more expected ( Belle II , LHCb, ATLAS, CMS ) Λ LE • In many cases no SM background: e.g., LFV, EDMs • For some modes accurate calculations of hadronic uncertainties essential, e.g. CPV in hadronic Tau decays Tau leptons very important to look for New Physics ! 5

1.2 τ lepton as a unique probe of new physics • A lot of progress in tau physics since its discovery on all the items described before important experimental efforts from LEP , CLEO, B factories: Babar, Belle, BES, VEPP-2M, LHCb, neutrino experiments , … Number of τ pairs Experiment More to come from LHCb, BES, LEP ~3x10 5 VEPP-2M, Belle II, CMS, ATLAS, CLEO ~1x10 7 HL/HI LHC BaBar ~5x10 8 Belle ~9x10 8 But τ physics has still potential • Belle II ~10 12 “ unexplored frontiers ” deserve future exp. & th. efforts • In the following, some selected examples 6 Emilie Passemar

1.3 The Program Adapted from Talk by Y. Grossman@CLFV2013 Muon LFV Intensity Frontier Charged Lepton µ + → e + γ ν e ↔ ν µ WG’13 µ + → e + e + e − ν e ↔ ν τ ν µ ↔ ν τ µ − N → e − N µ − N → e + N ′ µ + e − → µ − e + NeutrinoOscillations τ → ℓγ τ → ℓℓ + i ℓ − µ → µ γ LFV j τ → ℓ + hadrons ( g − 2) µ , (EDM) µ Tau LFV τ → τγ Muon LFC ( g − 2) τ , (EDM) τ CPV in τ → K πν τ τ → K ππν τ Tau LFC τ → N πν τ Thanks to Ba Emilie Passemar 7

2. Charged Lepton-Flavour Violation

2.1 Introduction and Motivation • Lepton Flavour Number is an « accidental » symmetry of the SM (m ν =0) • In the SM with massive neutrinos effecEve CLFV verEces are Eny due to GIM suppression unobservably small rates! µ → e γ E.g.: e , µ µ , τ 2 Δ m 1 i ) = 3 α 2 ( ∑ Br µ → e γ < 10 − 54 * U µ i U ei 32 π 2 M W i = 2,3 Petcov’77, Marciano & Sanda’77, Lee & Shrock’77 … ( ) < 10 − 40 ⎡ ⎤ Br τ → µ γ ⎣ ⎦ • Extremely clean probe of beyond SM physics • In New Physics models: seazible effects Comparison in muonic and tauonic channels of branching raEos, conversion rates and spectra is model-diagnosEc Emilie Passemar 9

2.1 Introduction and Motivation tτ � tτ � • In New Physics scenarios CLFV can reach observable levels in several � channels Talk by D. Hitlin @ CLFV2013 • But the sensitivity of particular modes to CLFV couplings is model dependent • Comparison in muonic and tauonic channels of branching ratios, conversion rates and spectra is model-diagnostic Emilie Passemar 10

Emilie Passemar 2.2 Tau LFV • • Several processes: 10 − 8 10 − 6 48 LFV modes studied at Belle and BaBar e − γ µ − γ − e π 0 µ − π 0 − e K 0 S µ − K 0 S − e η µ − − η e η′ (958) µ − η′ (958) e − ρ 0 µ − ρ 0 τ → ℓ γ , τ → ℓ α ℓ β ℓ β , τ → ℓ Y − e ω µ − 90% CL upper limits on τ LFV decays − ω e ● K ∗ (892) µ − 0 K ∗ ATLAS (892) e − 0 K ∗ (892) µ − 0 ∗ K (892) 0 − e φ µ − φ e − f BaBar (980) 0 µ − f (980) 0 − e e + − e − e µ + µ − µ − + e µ − Belle µ − + e e − e − µ + e − µ − µ + µ − ● e − π + π − CLEO e + π − π − µ − π + π − µ + π − π − − e π + K − e − K + π − LHCb e + π − K − − e K 0 P , S , V , PP ,... K 0 S − e S K + K − + e K − K − µ − π + K − µ − K + π − µ + π − K − µ − K 0 K 0 S µ − Spring 2017 S + K K − µ + HFLAV K − K − π − Λ π − Λ p µ − µ − p µ + µ − 11

Emilie Passemar 2.2 Tau LFV • • Several processes: 10 − 8 10 − 6 Expected sensiEvity 10 -9 or beWer at LHCb, ATLAS, CMS, Belle II, HL-LHC? e − γ µ − γ − e π 0 µ − π 0 − e K 0 S µ − K 0 S − e η µ − − η e η′ (958) µ − η′ (958) e − ρ 0 µ − ρ 0 τ → ℓ γ , τ → ℓ α ℓ β ℓ β , τ → ℓ Y − e ω µ − 90% CL upper limits on τ LFV decays − ω e ● K ∗ (892) µ − 0 K ∗ ATLAS (892) e − 0 K ∗ (892) µ − 0 ∗ K (892) 0 − e φ µ − φ e − f BaBar (980) 0 µ − f (980) 0 − e e + − e − e µ + µ − µ − + e µ − Belle µ − + e e − e − µ + e − µ − µ + µ − ● e − π + π − CLEO e + π − π − µ − π + π − µ + π − π − − e π + K − e − K + π − LHCb e + π − K − − e K 0 P , S , V , PP ,... K 0 S − e S K + K − + e K − K − µ − π + K − µ − K + π − µ + π − K − µ − K 0 K 0 S µ − Spring 2017 S + K K − µ + HFLAV K − K − π − Λ π − Λ p µ − µ − p µ + µ − 12

Approximate number of decays studied τ 5 6 7 8 9 10 10 10 10 10 10 10 90% CL Upper Limit on Branching Ratio -2 10 S. Banerjee’17 τ → µ γ MarkII τ → µ η ARGUS -4 τ → µ µ µ 10 DELPHI CLEO -6 10 Belle BaBar LHCb -8 10 mSUGRA + seesaw SUSY + SO(10) SM + seesaw Belle II SUSY + Higgs -10 10 1980 1990 2000 2010 2020 YEAR B2TIP’18 Emilie Passemar 13

2.3 Effective Field Theory approach See e.g. Black, Han, He, Sher’02 (6) L = L SM + C (5) C i Λ O (5) + ∑ + ... (6) Brignole & Rossi’04 Λ 2 O i Dassinger et al.’07 i Matsuzaki & Sanda’08 Giffels et al.’08 Crivellin, Najjari, Rosiek’13 • Build all D>5 LFV operators: Petrov & Zhuridov’14 Cirigliano, Celis, E.P.’14 Ø Dipole: ! τ D ⊃ − C D e.g. ! µ Λ 2 m τ µ σ µ ν P L , R τ F µ ν L eff τ µ Emilie Passemar 14

2.3 Effective Field Theory approach See e.g. Black, Han, He, Sher’02 (6) L = L SM + C (5) C i Λ O (5) + ∑ + ... (6) Brignole & Rossi’04 Λ 2 O i Dassinger et al.’07 i Matsuzaki & Sanda’08 Giffels et al.’08 Crivellin, Najjari, Rosiek’13 • Build all D>5 LFV operators: Petrov & Zhuridov’14 Cirigliano, Celis, E.P.’14 D ⊃ − C D Ø Dipole: Λ 2 m τ µ σ µ ν P L , R τ F µ ν L eff Ø Lepton-quark (Scalar, Pseudo-scalar, Vector, Axial-vector): q ϕ ≡ h 0 , H 0 , A 0 τ C S , V S , V ⊃ − Γ ≡ 1 2 m τ m q G F µ Γ P L , R τ q Γ q L eff e.g. Λ q µ μ e µ τ Γ ≡ γ µ • q q Emilie Passemar 15

2.3 Effective Field Theory approach See e.g. Black, Han, He, Sher’02 (6) L = L SM + C (5) C i Λ O (5) + ∑ + ... (6) Brignole & Rossi’04 Λ 2 O i Dassinger et al.’07 i Matsuzaki & Sanda’08 Giffels et al.’08 Crivellin, Najjari, Rosiek’13 • Build all D>5 LFV operators: Petrov & Zhuridov’14 Cirigliano, Celis, E.P.’14 D ⊃ − C D Ø Dipole: Λ 2 m τ µ σ µ ν P L , R τ F µ ν L eff C S , V S ⊃ − 2 m τ m q G F µ Γ P L , R τ q Γ q Ø Lepton-quark (Scalar, Pseudo-scalar, Vector, Axial-vector): L eff Λ Ø Integrating out heavy quarks generates gluonic operator G ⊃ − C G a G a 1 2 m τ G F µ P L , R τ G µ ν µ ν Λ 2 µ P L , R τ QQ à L eff Λ q ϕ ≡ h 0 , H 0 , A 0 τ • q µ Emilie Passemar 16