B2TIP view on Belle II s Emilie Passemar rd Indiana - - PowerPoint PPT Presentation

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B2TIP view on Belle II

Emilie Passemar

Emilie Passemar Indiana University/Jefferson Laboratory RADPyC'17, CINVESTAV Mexico, May 23, 2017

https://confluence.desy.de/display/BI/B2TiP+ReportStatus

s rd

s

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Outline :

1. Introduction and Motivation: Why studying flavour physics? 2. Belle II Theory Interface Initiative and Golden Channels for Belle II 3. Examples 4. Conclusion and outlook

Emilie Passemar

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• 1. Introduction and Motivation:

Why studying flavour physics?

Emilie Passemar

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• New era in particle physics :

(unexpected) success of the Standard Model: a successful theory of microscopic phenomena with no intrinsic energy limitation

• Several decades of

experimental successes Ø Gauge sector (LEP, SLC) Ø Prediction of the quark top before its discovery Ø CP violation measured in Kaons decays (NA48, KLOE, KTeV), and B decays (BaBar,

Belle)

Ø Higgs boson

1.1 The triumph of the Standard Model

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• Was this unexpected?

Not really! Consistent with (pre-LHC) indications coming from indirect NP searches (EWPO + flavour physcs)

• Shall we continue to test the Standard Model and search for New Physics?

Yes! Despite its phenomenological successes, the SM has some deep unsolved problems: – hierarchy problem – flavour pattern – dark-matter, etc….

• Strong interaction not so well understood:

confinement, etc

1.2 Quest for New Physics

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• Shall we continue to test the Standard Model and search for New Physics?

Yes! Despite its phenomenological successes, the SM has some deep unsolved problems: – hierarchy problem – flavour pattern – dark-matter, etc…. – Strong interaction not so well understood: confinement etc

• Consider the SM as as an effective theory,

i.e. the limit –in the accessible range

• f energies and effective couplings–
• f a more fundamental theory, with

– new degrees of freedom – new symmetries

1.2 Quest for New Physics

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H

Higgs 3 générations 3 generations

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• Where do we look? Everywhere!

search for New Physics with a broad search strategy given the lack of

clear indications on the SM-EFT boundaries (both in terms of energies and effective couplings)

1.2 Quest for New Physics

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Key unique role of Flavour Physics e+ e- machines such as Belle II offer a very clean environment Where is the tail?

• Y. Grossman@KEKFF’14

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1.3 Belle II environment

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e+ e− b¯ b b¯ u ¯ bu Υ(1S) = hb¯ bi Υ(4S) = hb¯ bi

B!threshold

B− B+

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1.3 Belle II environment

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e+ b¯ b b¯ u ¯ bu ¯ cu

V

ub

W − ` ¯ ν` ….

V

ub

W − c¯ u π− …. D0 B− B+ ¯ D0

mi

Semi-Inclusive hadronic ‘tagging’ side

• tanc

Signal side

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1.4 Recap of the last decade of BaBar & Belle: a rich harvest

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Un

Year

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

• 1

Integrated Luminosity in fb 200 400 600 800 1000 1200 1400 1600 1800

Observation of CP violation in B-meson system Observation of B → K(*)ll Evidence for direct CP violation in B → K+훑- Measurements of mixing-induced CP violation in B → 훗Ks, η’Ks, … Observation of b → d 후 Evidence for B → 훕 흼 Observation of direct CP violation in B →흅+훑- Evidence for D0 mixing Nobel prize to KM / Decisive confirmation of CKM picture Excess in B → D(*) 훕 흼

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• Baryon asymmetry in cosmology

→ New sources of CPV in quarks and charged leptons

• Quark and Lepton flavour & mass hierarchy

→ L-R symmetry, extended gauge sector, charged Higgs

• Finite neutrino masses

→ Tau LFV

• 19 free parameters

→ Extensions of SM relate some GUTs

• Puzzling nature of exotic “new” QCD states.
• The hidden universe (dark matter)

1.5 The case for new physics manifesting in Belle II

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1.6 Belle II expectations

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At the KEK 2014 workshop, the working g choose the 5 golden observable (to be a

Highlights of the KEK 2014 workshop

elle II =

• (σ2

stat + σ2 syst) LBelle 50ab−1 + σ2 ired

y charmless! Time dependent CPV in π0π0 New PID (be B->

Year 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 Normalised Integrated Luminosity 1 10

2

10 ]

• 1

LHCb [fb ]

• 1

Belle (II) [ab Belle II Projection (March 2015)

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1.6 Belle II expectations

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Goal of Be!e II/SuperKEKB"

9 months/year 20 days/month

Phase-1

Integrated luminosity (ab-1) Peak luminosity (cm-2s-1)

Calendar Year

B → µ ν Discovery Resolve |Vub| puzzle τ LFV Discovery 10 ab-1 B→Kee LFUV New Physics B→Kνν SM Discovery B→ η’ Ks New CP WR in B→ργ

Integrated luminosity [ab-1] Peak luminosity [cm-2s-1]

Zb, Wb discovery < 1 ab-1 Confirm B→D*τ ν New physics Φ2, Φ3 < 2o

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• 2. Belle II Theory Interface Initiative and Golden

Channels for Belle II

Emilie Passemar

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2.1 Why B2TIP?

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KEK where Belle II is hosted is the natural gathering point where flavour physics experts meet to discuss and develop topics of flavour physics for Belle II.

Deliverable: “KEK green report” by the early 2017

NEW IDEAS What’s new in Belle II compared to Babar/Belle?

➡ Efficiencies and precision of

the new hardware

➡ New analysis softwares and

methods

What’s new in theory after Babar/ Belle & LHCb result?

➡ Progresses in QCD ➡ New physics models and their

constraints

➡ New observables

See details on the slide at the kickoff meeting:

http://kds.kek.jp/getFile.py/access?contribId=14&sessionId=0&resId=0&materialId=slides&confId=15226

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See details on the B2TiP website

https://belle2.cc.kek.jp/~twiki/bin/view/Public/B2TIP

WG1

• G. De Nardo, A. Zupanic, M. Tanaka, F. Tackmann, A. Kronfeld

WG2

• A. Ishikawa, J. Yamaoka, U. Haisch, T. Feldmann

WG3

• T. Higuchi, L. Li Gioi, J. Zupan, S. Mishima

WG4

• J. Libby, Y. Grossman, M. Blanke

WG5

• P. Goldenzweig, M. Beneke, C.-W

. Chiang, S. Sharpe

WG6

• G. Casarosa, A. Schwartz, A. Kagan, A. Petrov

WG7

Ch.Hanhart, R.Mizuk, R.Mussa, C.Shen, Y.Kiyo, A.Polosa, S.Prelovsek

WG8

• K. Hayasaka, T. Feber, E. Passemar, J. Hisano

WGNP

R.Itoh, F.Bernlochner, Y.Sato, U.Nierste, L.Silvestrini, J.Kamenik, V .Lubicz

I: Leptonic/Semi-leptonic II: Radiative/Electroweak III: phi1(beta)/phi2(alpha) IV: phi3 (gamma) V: Charmless/hadronic B decays VI: Charm VII: Quarkonium(like) VIII: Tau & low multiplicity NP: New Physics

2.2 9 working groups

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See details on the B2TiP website

https://belle2.cc.kek.jp/~twiki/bin/view/Public/B2TIP

WG1

• G. De Nardo, A. Zupanic, M. Tanaka, F. Tackmann, A. Kronfeld

WG2

• A. Ishikawa, J. Yamaoka, U. Haisch, T. Feldmann

WG3

• T. Higuchi, L. Li Gioi, J. Zupan, S. Mishima

WG4

• J. Libby, Y. Grossman, M. Blanke

WG5

• P. Goldenzweig, M. Beneke, C.-W

. Chiang, S. Sharpe

WG6

• G. Casarosa, A. Schwartz, A. Kagan, A. Petrov

WG7

Ch.Hanhart, R.Mizuk, R.Mussa, C.Shen, Y.Kiyo, A.Polosa, S.Prelovsek

WG8

• K. Hayasaka, T. Feber, E. Passemar, J. Hisano

WGNP

R.Itoh, F.Bernlochner, Y.Sato, U.Nierste, L.Silvestrini, J.Kamenik, V .Lubicz

I: Leptonic/Semi-leptonic II: Radiative/Electroweak III: phi1(beta)/phi2(alpha) IV: phi3 (gamma) V: Charmless/hadronic B decays VI: Charm VII: Quarkonium(like) VIII: Tau & low multiplicity NP: New Physics

2.2 9 working groups

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Crucial contribution from Mexican groups [Experiment and Theory]

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2.3 Table of Golden modes for B physics

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Observables Expected th. accuracy Expected exp. uncer- tainty Facility (2025) UT angles & sides 1 [] *** 0.4 Belle II 2 [] ** 1.0 Belle II 3 [] *** 1.0 Belle II/LHCb |Vcb| incl. *** 1% Belle II |Vcb| excl. *** 1.5% Belle II |Vub| incl. ** 3% Belle II |Vub| excl. ** 2% Belle II/LHCb CPV S(B → K0) *** 0.02 Belle II S(B → ⌘0K0) *** 0.01 Belle II A(B → K0⇡0)[102] *** 4 Belle II A(B → K+⇡) [102] *** 0.20 LHCb/Belle II (Semi-)leptonic B(B → ⌧⌫) [106] ** 3% Belle II B(B → µ⌫) [106] ** 7% Belle II R(B → D⌧⌫) *** 3% Belle II R(B → D⇤⌧⌫) *** 2% Belle II/LHCb Radiative & EW Penguins B(B → Xs) ** 4% Belle II ACP (B → Xs,d) [102] *** 0.005 Belle II S(B → K0

S⇡0)

*** 0.03 Belle II S(B → ⇢) ** 0.07 Belle II B(Bs → ) [106] ** 0.3 Belle II B(B → K⇤⌫⌫) [106] *** 15% Belle II B(B → K⌫⌫) [106] *** 20% Belle II R(B → K⇤``) ** 0.03 Belle II/LHCb

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2.3 Golden modes for Tau, Low Multiplicity and EW

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• B factories are also Tau factories!

45 billion 𝜐+𝜐− pairs in full dataset from 𝜏(𝜐+𝜐−)E=𝛷(4S)= 0.9 nb

• Golden modes:

– Tau LFV : τ → 3µ/µγ/µh/µhh – CP violation in τ → Kπντ and/or τ → Kππντ – Precision two track final state: e+e- → π+π- – Dark photon → invisible

Experiment Number of τ pairs LEP ~3x105 CLEO ~1x107 BaBar ~5x108 Belle ~9x108 Belle II ~1012

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2.3 Golden modes for Tau, Low Multiplicity and EW

20 Emilie Passemar

• B factories are also Tau factories!

45 billion 𝜐+𝜐− pairs in full dataset from 𝜏(𝜐+𝜐−)E=𝛷(4S)= 0.9 nb

• Golden/Silver modes:

Experiment Number of τ pairs LEP ~3x105 CLEO ~1x107 BaBar ~5x108 Belle ~9x108 Belle II ~1012 P r

• c

e s s O b s e r v a b l e T h e

• r

y S y s . l i m i t ( D i s c

• v

e r y ) [ a b

• 1

] v s L H C b / B E S I I I v s B e l l e A n

• m

a l y N P

• ⌧ → µ

Br. ? ? ?

• ? ? ?

? ? ? ? ? ? ?

• ⌧ → lll

Br. ? ? ?

• ? ? ?

? ? ? ? ? ? ?

• ⌧ → K⇡⌫

ACP ? ? ?

• ? ? ?

? ? ? ?? ??

• e+e → A0(→invisible)
• ? ? ?
• ? ? ?

? ? ? ? ? ? ?

• e+e → A0(→ `+`)
• ? ? ?
• ? ? ?

? ? ? ? ? ? ?

• ⇡ form factor

g − 2 ??

• ? ? ?

?? ?? ? ? ?

• ISR e+e → ⇡⇡ g-2

g − 2 ??

• ? ? ?

? ? ? ?? ? ? ?

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2.3 Golden modes for Tau, Low Multiplicity and EW

21 Emilie Passemar

• B factories are also Tau factories!

45 billion 𝜐+𝜐− pairs in full dataset from 𝜏(𝜐+𝜐−)E=𝛷(4S)= 0.9 nb

• Golden modes:

– Tau LFV : τ → 3µ/µγ/µh/µhh – CP violation in τ → Kπντ and/or τ → Kππντ – Precision two track final state: e+e- → π+π- – Dark photon → invisible

Experiment Number of τ pairs LEP ~3x105 CLEO ~1x107 BaBar ~5x108 Belle ~9x108 Belle II ~1012

• G. Lopez-Castro’17

SLIDE 22

2.3 Golden modes for Tau, Low Multiplicity and EW

22 Emilie Passemar

• B factories are also Tau factories!

45 billion 𝜐+𝜐− pairs in full dataset from 𝜏(𝜐+𝜐−)E=𝛷(4S)= 0.9 nb

• Golden modes:

– Tau LFV : τ → 3µ/µγ/µh/µhh Interest of Mexican Group in study

• f 𝜐− → l−(𝜌0𝜌0,𝜌0𝜃,𝜃𝜃) channels

– CP violation in τ → Kπντ and/or τ → Kππντ

τ− → KS 𝜌0𝜌−𝜉𝜐: BR and spectrum measurements interesting for CP

violation studies and isospin breaking in K*(892) – Precision two track final state: e+e- → π+π- – Dark photon → invisible

Experiment Number of τ pairs LEP ~3x105 CLEO ~1x107 BaBar ~5x108 Belle ~9x108 Belle II ~1012

Mexican involvment

• G. Lopez-Castro’17

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• 3. Examples

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• The CKM Mechanism source of Charge Parity Violation in SM
• Unitary 3x3 Matrix, parametrizes rotation between mass and weak interaction

eigenstates in Standard Model

3.1 Probing the CKM mechanism

24 Emilie Passemar

  d0 s0 b0   =   Vud Vus Vub Vcd Vcs Vcb Vtd Vts Vtb     d s b  

Weak Eigenstates Mass Eigenstates CKM Matrix

1 1 1

λ λ2 λ λ3 λ3 λ2 ak and Mass Eigenstates

SLIDE 25

• The CKM Mechanism source of Charge Parity Violation in SM
• Unitary 3x3 Matrix, parametrizes rotation between mass and weak interaction

eigenstates in Standard Model

• Fully parametrized by four parameters if unitarity holds: three real

parameters and one complex phase that if non-zero results in CPV

• Unitarity can be visualized using triangle equations, e.g.

3.1 Probing the CKM mechanism

25 Emilie Passemar

  d0 s0 b0   =   Vud Vus Vub Vcd Vcs Vcb Vtd Vts Vtb     d s b  

Weak Eigenstates Mass Eigenstates CKM Matrix

V

VCKMV †

CKM = 1

→ V ∗

ubVud + V ∗ cbVcd + V ∗ tbVtd = 0

SLIDE 26

Existence of CPV phase established in 2001 by BaBar & Belle

• Picture still holds 15 years later, constrained with remarkable precision
• But: still leaves room for new physics contributions

CKM picture over the years: from discovery to precision

26 Emilie Passemar

d

m

• K
• K
• s

m

• &

d

m

• ub

V

• sin 2
• 1.0
• 0.5

0.0 0.5 1.0 1.5 2.0

• 1.5
• 1.0
• 0.5

0.0 0.5 1.0 1.5

excluded area has CL > 0.95 Summer 2001

CKM

f i t t e r

• d

m

• K
• K
• s

m

• &

d

m

• ub

V

• sin 2

(excl. at CL > 0.95) < 0

• sol. w/ cos 2

excluded at CL > 0.95

• 1.0
• 0.5

0.0 0.5 1.0 1.5 2.0

• 1.5
• 1.0
• 0.5

0.0 0.5 1.0 1.5

excluded area has CL > 0.95 EPS 15

CKM

f i t t e r

2001 2015

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3.1 Probing the CKM mechanism

27 Emilie Passemar

• World average

Input 2016 Belle II (+LHCb) 2025 |Vub|(semileptonic)[103] 4.01 ± 0.08 ± 0.22 ±0.10 |Vcb|(semileptonic)[103] 41.00 ± 0.33 ± 0.74 ±0.57 B(B → ⌧⌫) 1.08 ± 0.21 ±0.04 sin 2 0.691 ± 0.017 ±0.008 [] 73.2+6.3

7.0

±1.5 (±1.0) ↵[] 87.6+3.5

3.3

±1.0 ∆md 0.510 ± 0.003

• ∆ms

17.757 ± 0.021

• B(Bs → µµ)

2.8+0.7

0.6

(±0.5) fBs 0.224 ± 0.001 ± 0.002 0.001 BBs 1.320 ± 0.016 ± 0.030 0.010 fBs/fBd 1.205 ± 0.003 ± 0.006 0.005 BBs/BBd 1.023 ± 0.013 ± 0.014 0.005

Expect substantial improvements to tree constraints!

• d

m

• K
• K
• s

m

• &

d

m

• ub

V

• sin 2

(excl. at CL > 0.95) < 0

• sol. w/ cos 2

excluded at CL > 0.95

• 1.0
• 0.5

0.0 0.5 1.0 1.5 2.0

• 1.5
• 1.0
• 0.5

0.0 0.5 1.0 1.5

excluded area has CL > 0.95 EPS 15

CKM

f i t t e r

2015

SLIDE 28

E.g: Solving the discrepancy Vub/Vcb

28 Emilie Passemar

U

3

10 × |

ub

V | 2.5 3 3.5 4 4.5 5 5.5 6 PDG World averages

• Prel. 2015

2014 2012 2010 2008 2006 2004

Sizeable tension in exclusive and inclusive |Vub| & |Vcb|

• Both methods considered theoretical and experimental mature
• Individual determinations leave a consistent picture

3

10 × |

cb

V | 36 37 38 39 40 41 42 43 44 45 PDG World averages

• Prel. 2015

2014 2012 2010 2008 2006 2004

Vqb

W −

−

¯ ν b q u u

2.3σ 3.4σ

• About 2.3σ and 3.4σ disagreement between incl. and excl. for |Vcb| & |Vub|, respectively

SLIDE 29

• A renewed interest in possible violations of LFU has been triggered by two

very different sets of observations in B physics:

• 1. LFU test in b → c charged currents: τ vs. light leptons (µ, e) :

3.2 Lepton universality & NP

29 Emilie Passemar

bL cL

W

τL

νL

bL cL

τL

νL

NP

SM predic*on solid: f.f. uncertainty cancels (to a good extent...) in the ra*o Consistent results by 3 different exps 3.9σ excess over SM (combining D and D*)

SLIDE 30

3.2 Lepton universality & NP

30 Emilie Passemar

R(D)

0.2 0.3 0.4 0.5 0.6

R(D*)

0.2 0.25 0.3 0.35 0.4 0.45 0.5

BaBar, PRL109,101802(2012) Belle, PRD92,072014(2015) Belle, arXiv:1603.06711 LHCb, PRL115,111803(2015) HFAG Average (Winter 2016) SM Prediction Belle II, 5 ab-1 Belle II, 50 ab-1

R(D)

~ currently 3σ deviation? Belle II prospect (with the current Belle central value) 14(6)σ deviation with 50(5)ab-1 of data!

SM

• K. Hara for B2TiP LAL NP-workshop

SLIDE 31

• A renewed interest in possible violations of LFU has been triggered by two

very different sets of observations in B physics:

• 2. LFU test in b → s neutral currents: µ vs. e :

3.2 Lepton universality & NP

31 Emilie Passemar

2.6σ deviation from the SM

vs. RK = Br[B+ → K+µ+µ−][1,6] Br[B+ → K+e+e−][1,6] = 0.745 · (1 ± 13%)

RSM

K

= 1.003 ± 0.0001 vs.

vs LHCb’14

SLIDE 32

• 2. LFU test in b → s neutral currents: µ vs. e :

3.2 Lepton universality & NP

32 Emilie Passemar

“RK∗ = Br(B → K ∗µµ)/Br(B → K ∗ee) anomaly”

• S. Bifani, LHCb@CERN’17

Compatibility with SM 2.2-2.4σ (low-q2) 2.4-2.5σ (central-q2)

SLIDE 33

• A renewed interest in possible violations of LFU has been triggered by two

very different sets of observations in B physics

• This has triggered intense theoretical activities:

D & D* channels are well consistent with a universal enhancement (~15%) of the SM bL → cL τL νL amplitude (RH or scalar amplitudes disfavored)

• Natural to conceive NP models where LFU is violated more in processes

involving 3rd gen. quarks & leptons (↔ hierarchy in Yukawa coupl.)

• Belle II contribution very important:

– Cleanest environment: Belle covers ~70% of all tau Inclusive Br decays! – Perform angular distribution analyses

3.2 Lepton universality & NP

33 Emilie Passemar

SLIDE 34

3.3 Tau LFV

• Lepton Flavour Number is an « accidental » symmetry of the SM (mν=0)
• In the SM with massive neutrinos effec*ve CLFV ver*ces are *ny

due to GIM suppression unobservably small rates! E.g.:

• Extremely clean probe of beyond SM physics
• In New Physics models: seazible effects

Comparison in muonic and tauonic channels of branching ra*os, conversion rates and spectra is model-diagnos*c

Emilie Passemar 34

µ → eγ

Br µ → eγ

( ) = 3α

32π U µi

* i=2,3

∑

Uei Δm1i

2

MW

2 2

< 10−54

e

µ

Br τ → µγ

( ) < 10−40

⎡ ⎣ ⎤ ⎦

Petcov’77, Marciano & Sanda’77, Lee & Shrock’77…

SLIDE 35

• HFLAV

Spring 2017

10−8 10−6

e − γ µ − γ e − π µ − π e − K S µ − K S e − η µ − η e − η′(958) µ − η′(958) e − ρ µ − ρ e − ω µ − ω e − K ∗ (892) µ − K ∗ (892) e − K ∗ (892) µ − K ∗ (892) e − φ µ − φ e − f (980) µ − f (980) e − e + e − e − µ + µ − µ − e + µ − µ − e + e − e − µ + e − µ − µ + µ − e − π + π − e + π − π − µ − π + π − µ + π − π − e − π + K − e − K + π − e + π − K − e − K S K S e − K + K − e + K − K − µ − π + K − µ − K + π − µ + π − K − µ − K S K S µ − K + K − µ + K − K − π − Λ π − Λ pµ − µ − pµ + µ −

• ATLAS

BaBar Belle CLEO LHCb

90% CL upper limits on τ LFV decays

3.3 Tau LFV

• Several processes:
• 48 LFV modes studied at Belle and BaBar

Emilie Passemar

τ → ℓγ , τ → ℓ α ℓβℓ β , τ → ℓY

P, S, V, PP,...

35

SLIDE 36

Emilie Passemar 36

YEAR 1980 1990 2000 2010 2020

• 10

10

• 8

10

• 6

10

• 4

10

• 2

10 decays studied τ Approximate number of

5

10

6

10

7

10

8

10

9

10

10

10 MarkII ARGUS DELPHI CLEO Belle BaBar LHCb Belle II mSUGRA + seesaw SUSY + SO(10) SM + seesaw SUSY + Higgs

90% CL Upper Limit on Branching Ratio γ µ → τ η µ → τ µ µ µ → τ

• I. Heredia

MWPF2015

Belle II can reduce most of theese limits by 1 ~2 orders of magnitude

• S. Banerjee’17

SLIDE 37

• 4. Conclusion and outlook

Emilie Passemar

SLIDE 38

Conclusion and outlook

• The SM has been very successful so far to describe phenomenology

But this is not the end of the story

• Belle II gives us a unique opportunity to explore the SM very precisely in the

sector of flavour physics

• Important B2TIP initiative to assess the discovery opportunities
• Examples where Belle II can make a difference:
• CKM determination and Unitary triangles
• LFU tests in B physics
• Tau LFVs
• But many others, e.g.: Quarkoniums, exotics, D physics, CP asymmetries,

weak mixing angle, second class currents, Di-photon physics, Dark sector, etc.

• Important Mexican contributions to Belle II in many sectors

We will hear more during the conference

• Stay tuned! Exciting times are ahead of us

Emilie Passemar 38

SLIDE 39

• 7. Back-up

SLIDE 40

Conclusion and outlook

• Leptonic Universality hints
• Hadronic τ-decays very interes*ng to study

– Very precise determina*on of αS – Extrac*on of Vus

• Charged LFV are a very important probe of new physics
• Several topics extremely interes*ng to study that I did not address:

– Michel parameters – CPV asymmetry in τ → Kπντ – EDM and g-2 of the tau – Neutrino physics

• A lot of very interesLng physics remains to be done in the tau sector!

Emilie Passemar 40

SLIDE 41

• 5. LFC processes: anomalous magnetic moment
• f the muon

SLIDE 42

5.1 Introduction

• The gyromagnetic factor of the muon is modified by loop contribution
• We can also study ae with better experimental precision

but if new physics heavy then more sensitivity in aµ

• aτ even more sensitive but insufficient experimental

accuracy

• But ae important if NP is light

Important constraints on NP scenarios ns

γ µ

?

Giudice, Paradisi, Passera’12 Eidelman, Giacomini, Ignatov, Passera’07

Emilie Passemar 42

SLIDE 43

5.2 Contribution to (g-2)µ

Weak

γ µ γ γ µ ν µ γ µ µ γ µ

Z

µ γ γ

µ µ γ γ µ µ µ γ µ γ γ µ ν µ

W W

γ µ µ γ µ

µ γ γ

µ µ γ γ µ µ µ

QED

γ µ γ γ µ ν µ γ µ µ γ µ

µ γ γ

µ µ γ γ µ µ µ

SUSY ... ?

γ µ γ γ µ ν µ γ µ µ γ µ

µ γ γ

µ µ γ γ µ µ µ γ µ γ γ µ ν µ γ µ µ γ µ

µ γ γ

µ µ γ γ µ µ µ

 χ  χ  ν   χ 0 

... or some unknown type of new physics ?

γ µ γ γ µ ν µ γ µ µ γ µ

Z

µ γ γ

µ µ γ γ µ µ µ

?

Hadronic

h

γ µ γ γ µ ν µ γ µ µ γ µ

µ γ γ

µ µ γ γ µ µ µ γ µ γ γ µ ν µ γ µ µ γ µ

h µ γ γ

µ µ γ γ µ µ µ

“Light-by-light scattering” … or no effect on aµ, but new physics at the LHC? That would be interesting as well !!

Need to compute the SM prediction with high precision! Not so easy!

Emilie Passemar 43

Hoecker’11

SLIDE 44

5.3 Confronting measurement and prediction

µ γ

γ

h a d had

γ

Theoretical Prediction:

γ µ γ γ µ ν µ γ µ µ γ µ

µ γ γ

µ µ γ γ µ µ µ γ µ γ γ µ ν µ γ µ µ γ µ

µ γ γ

µ µ γ γ µ µ µ γ µ γ γ µ ν µ γ µ µ γ µ

µ γ γ

µ µ γ γ µ µ µ γ µ γ γ µ ν µ γ µ µ γ µ

µ γ γ

µ µ γ γ µ µ µ γ µ γ γ µ ν µ γ µ µ γ µ

µ γ γ

µ µ γ γ µ µ µ γ µ γ γ µ ν µ γ µ µ γ µ

µ γ γ

µ µ γ γ µ µ µ γ µ γ γ µ ν µ γ µ µ γ µ

µ γ γ

µ µ γ γ µ µ µ γ µ γ γ µ ν µ γ µ µ γ µ

h µ γ γ

µ µ γ γ µ µ µ

“Light-by-light scattering”

Emilie Passemar 44

Lafferty, summary talk@Tau2014 Blum et al.’13

SLIDE 45

• Hadronic contribution cannot be computed from first principles

due to low-energy hadronic effects

• Use analyticity + unitarity real part of photon polarisation function from

dispersion relation over total hadronic cross section data

• Leading order hadronic vacuum polarization :
• Low energy contribution dominates : ~75% comes from s < (1 GeV)2

ππ contribution extracted from data

5.4 Towards a model independent determination of HVP and LBL

( )

2

2 2 , 2 2 4

( ) ( ) 3

had LO V m

m K s a ds R s s

π

µ µ

α π

∞

=

∫

( ) ( )

( )

V

e e hadrons R s e e σ σ µ µ

+ − + − + −

→ = → Emilie Passemar

µ γ

γ

h a d had

γ

45

SLIDE 46

• Huge 20-years effort by experimentalists and theorists to reduce error on

lowest-order hadronic part Ø Improved e+e– cross section data from Novisibirsk (Russia) Ø More use of perturbative QCD Ø Technique of “radiative return” allows to use data from Φ and B factories Ø Isospin symmetry allows us to also use τ hadronic spectral functions

• But still some progress

need to be done Ø Inconsistencies τ vs. e+e-: Isospin corrections? Ø Inconsistencies between ISR and direct data: Radiative corrections? Ø Lattice Calculation? New data expected from VEPP, KLOE2, BES-III? Belle II

5.4 Towards a model independent determination of HVP and LBL

Dominant Region

use QCD

• 46

SLIDE 47

• For light-by-light scattering: until recently it was believed that

dispersion relation approach not possible (4-point function)

• nly model dependent estimates
• But recent progress from Bern group: Colangelo, Hoferichter, Procura, Stoffer’14

Data driven estimate possible using dispersion relations!

5.4 Towards a model independent determination of HVP and LBL

γ µ γ γ µ ν µ γ µ µ γ µ

µ γ γ

µ µ γ γ µ µ µ γ µ γ γ µ ν µ γ µ µ γ µ

µ γ γ

µ µ γ γ µ µ µ γ µ γ γ µ ν µ γ µ µ γ µ

µ γ γ

µ µ γ γ µ µ µ γ µ γ γ µ ν µ γ µ µ γ µ

µ γ γ

µ µ γ γ µ µ µ γ µ γ γ µ ν µ γ µ µ γ µ

µ γ γ

µ µ γ γ µ µ µ γ µ γ γ µ ν µ γ µ µ γ µ

µ γ γ

µ µ γ γ µ µ µ γ µ γ γ µ ν µ γ µ µ γ µ

µ γ γ

µ µ γ γ µ µ µ γ µ γ γ µ ν µ γ µ µ γ µ

h µ γ γ

µ µ γ γ µ µ µ

ight

e+e− → e+e−π0 γπ → ππ γπ → ππ e+e− → π0γ e+e− → π0γ ω, φ → ππγ e+e− → ππγ ππ → ππ Pion transition form factor Fπ0γ∗γ∗

• q2

1, q2 2

• Partial waves for

γ∗γ∗ → ππ e+e− → e+e−ππ Pion vector form factor F π

V

Pion vector form factor F π

V

e+e− → 3π pion polarizabilities pion polarizabilities γπ → γπ ω, φ → 3π ω, φ → π0γ∗ ω, φ → π0γ∗

Emilie Passemar 47

SLIDE 48

• 5. CPV in tau decays

Emilie Passemar

SLIDE 49

• Experimental measurement :
• CP viola*on in the tau decays should be of opposite sign compared to the one

in D decays in the SM

0’

• –
• 5.1

τ → Kπντ CP violating asymmetry

49

A

Q =

Γ τ + → π +KS

0ντ

( ) − Γ τ − → π −KS

0ντ

( )

Γ τ + → π +KS

0ντ

( ) + Γ τ − → π −KS

0ντ

( )

S

K p K q K = + = +

L

K p K q K = −

KL KS = p

2 − q 2 ! 2Re ε K

( )

2 2

=

• p

q

( )

0.36 0.01 % ≈ ±

Bigi & Sanda’05

in the SM

Grossman & Nir’11

A

Qexp = -0.36 ± 0.23stat ± 0.11syst

( )%

2.8σ

from the SM!

BaBar’11 Grossman & Nir’11

AD = Γ D+ → π +KS

( ) − Γ D− → π −KS ( )

Γ D+ → π +KS

( ) + Γ D− → π −KS ( ) = -0.54 ± 0.14

( )%

Belle, Babar, CLOE, FOCUS

Emilie Passemar

SLIDE 50

• 5.1 τ → Kπντ CP violating asymmetry
• New physics? Charged Higgs, WL-WR mixings, leptoquarks, tensor interac*ons

(Devi, Dhargyal, Sinha’14)?

• Problem with this measurement? It would be great to have other

experimental measurements from Belle, BES III or Tau-Charm factory

• Measurement of the

direct contribu*on

• f NP in the angular

CP viola*ng asymmetry done by CLEO and Belle Belle does not see any asymmetry at the 0.2 - 0.3% level

Bigi’Tau12

Very difficult to explain! Belle’11

Emilie Passemar

SLIDE 51

system

• 5.2 Three body CP asymmetries

51

• Ex: τ → Kππντ
• A variety of CPV observables can be studied :

τ → Kππντ, τ → πππντ rate, angular asymmetries, triple products,…. Same principle as in charm, see Bevan’15 Difficulty : Treatement of the hadronic part Hadronic final state interac*ons have to be taken into account! Disentangle weak and strong phases

• More form factors, more asymmetries to build but same principles as for 2 bodies

e.g., Choi, Hagiwara and Tanabashi’98 Kiers, Li\le, Da\a, London et al.,’08 Mileo, Kiers and, Szynkman’14

Emilie Passemar

SLIDE 52

Lepton universality - HFAG 2016 prelim.

Standard Model for leptons λ, ρ = e, µ, τ (Marciano 1988) Γ[λ → νλρνρ(γ)] = Γλρ = ΓλBλρ = Bλρ τλ = GλGρm5

λ

192π3 f m2

ρ

m2

λ

! rλ

W rλ γ ,

where Gλ = g2

λ

4 √ 2M2

W

f (x) = 1 − 8x + 8x3 − x4 − 12x2lnx fλρ = f m2

ρ

m2

λ

! rλ

W = 1 + 3

5 m2

λ

M2

W

rλ

γ = 1 + α(mλ)

2π ✓ 25 4 − π2 ◆ Tests of lepton universality from ratios of above partial widths: ✓ gτ gµ ◆ = s Bτe Bµe τµm5

µfµer µ W r µ γ

ττ m5

τ fτer τ W r τ γ

= 1.0012 ± 0.0015 = s Bτe BSM

τe

✓ gτ ge ◆ = s Bτµ Bµe τµm5

µfµer µ W r µ γ

ττ m5

τ fτµr τ W r τ γ

= 1.0030 ± 0.0014 = s Bτµ BSM

τµ

✓ gµ ge ◆ = s Bτµ Bτe fτe fτµ = 1.0019 ± 0.0014

• precision: 0.20−0.23% pre-B-Factories ⇒ 0.14−0.15% today

thanks essentially to the Belle tau lifetime measurement, PRL 112 (2014) 031801

• rτ

γ = 1 − 43.2 · 10−4 and rµ γ = 1 − 42.4 · 10−4 (Marciano 1988),

MW from PDG 2013

SLIDE 53

Universality improved B(τ → eν¯ ν) and Rhad - HFAG 2016 prelim.

Universality improved B(τ → eν¯ ν)

• (M. Davier, 2005): assume SM lepton universality to improve Be = B(τ → e¯

νeντ) fit Be using three determinations:

I Be = Be I Be = Bµ · f (m2

e/m2 τ)/f (m2 µ/m2 τ)

I Be = B(µ → e¯

νeνµ) · (ττ/τµ) · (mτ/mµ)5 · f (m2

e/m2 τ)/f (m2 e/m2 µ) · (δτ γδτ W)/(δµ γδµ W)

[above we have: B(µ → e¯ νeνµ) = 1]

• Buniv

e

= (17.818 ± 0.022)%

HFAG-PDG 2016 prelim. fit

Rhad = Γ(τ → hadrons)/Γuniv(τ → eν¯ ν)

• Rhad = Γ(τ → hadrons)

Γuniv(τ → eν¯ ν) = Bhadrons Buniv

e

= 1 − Buniv

e

− f (m2

µ/m2 τ)/f (m2 e/m2 τ) · Buniv e

Buniv

e

I two different determinations, second one not “contaminated” by hadronic BFs

• Rhad = 3.6359 ± 0.0074

HFAG-PDG 2016 prelim. fit

• Rhad(leptonic BFs only) = 3.6397 ± 0.0070

HFAG-PDG 2016 prelim. fit

SLIDE 54

Alberto Lusiani – Pisa Tau Decay Measurements

Tau mass

]

2

[MeV/c

τ

m

1776 1776.5 1777 1777.5 1778 PDG 2015 average 0.12 ± 1776.86 BES 2014 0.13 − 0.10 + 0.12 ± 1776.91 BaBar 2009 0.41 ± 0.12 ± 1776.68 KEDR 2007 0.15 ± 0.23 − 0.25 + 1776.81 Belle 2007 0.35 ± 0.13 ± 1776.61 OPAL 2000 1.00 ± 1.60 ± 1775.10 CLEO 1997 1.20 ± 0.80 ± 1778.20 BES 1996 0.17 − 0.25 + 0.21 − 0.18 + 1776.96 ARGUS 1992 1.40 ± 2.40 ± 1776.30 DELCO 1978 4.00 − 3.00 + 1783.00 PDG 2015

• most precise measurements by

e+e− colliders at τ +τ − threshold

I few events but very significant

SLIDE 55

Alberto Lusiani – Pisa Tau Decay Measurements

Tau lifetime

s]

• 15

[x 10

τ

τ

285 290 295 HFAG Summer 2014 0.52 ± 290.29 PDG 2014 average 0.50 ± 290.30 Belle 2013 0.33 ± 0.53 ± 290.17 Delphi 2004 1.00 ± 1.40 ± 290.90 L3 2000 1.50 ± 2.00 ± 293.20 ALEPH 1997 1.10 ± 1.50 ± 290.10 OPAL 1996 1.20 ± 1.70 ± 289.20 CLEO 1996 4.00 ± 2.80 ± 289.00

HFAG-Tau

Summer 2014

• LEP experiments, many methods

I impact parameter sum (IPS) I momentum dependent impact

parameter sum (MIPS

I 3D impact parameter sum (3DIP) I impact parameter difference (IPD) I decay length (DL)

• Belle

I 3-prong vs. 3-prong decay length I largest syst. error: alignment

New Vistas in Low-Energy Precision Physics (LEPP), 4-7 April 2016, Mainz, Germany 6 / 40

SLIDE 56

• New era in particle physics :

(unexpected) success of the Standard Model: a successful theory of microscopic phenomena with no intrinsic energy limitation

• Relies on

1.1 The triumph of the Standard Model

56 Emilie Passemar

SLIDE 57

• Shall we continue to test the Standard Model and search for New Physics?

Yes! Despite its phenomenological successes, the SM has some deep unsolved problems: – hierarchy problem – flavour pattern – dark-matter, etc….

1.2 Quest for New Physics

57 Emilie Passemar

Strong interaction not so well understood: confinement, etc

SLIDE 58

• New era in particle physics :

(unexpected) success of the Standard Model: a successful theory of microscopic phenomena with no intrinsic energy limitation

• Key results at LHC after run I + beginning of run II

– The Higgs boson (last missing piece of the SM) has been found: it looks very standard – The Higgs boson is “light” (mh ~ 125 GeV → not the heaviest SM particle) – No “mass-gap” above the SM spectrum (i.e. no unambiguous sign of NP up to ~ 1 TeV)

• Was this unexpected?

Not really! Consistent with (pre-LHC) indications coming from indirect NP searches (EWPO + flavour physcs)

1.1 The triumph of the Standard Model

58 Emilie Passemar

SLIDE 59

1.4 Belle II expectations

59 Emilie Passemar

Goal of Be!e II/SuperKEKB"

9 months/year 20 days/month

Phase-1

Integrated luminosity (ab-1) Peak luminosity (cm-2s-1)

Calendar Year

SLIDE 60

• A renewed interest in possible violations of LFU has been triggered by two

very different sets of observations in B physics:

• 1. LFU test in b → c charged currents: τ vs. light leptons (µ, e) :

3.2 Lepton universality & NP

60 Emilie Passemar

bL cL

W

τL

νL

bL cL

τL

νL

NP

SM predic*on solid: f.f. uncertainty cancels (to a good extent...) in the ra*o Consistent results by 3 different exps 4σ excess over SM (combining D and D*)

SLIDE 61

• A renewed interest in possible violations of LFU has been triggered by two

very different sets of observations in B physics:

• 2. LFU test in b → s neutral currents: µ vs. e :

3.2 Lepton universality & NP

61 Emilie Passemar

2.6σ deviation from the SM

vs. RK = Br[B+ → K+µ+µ−][1,6] Br[B+ → K+e+e−][1,6] = 0.745 · (1 ± 13%)

RSM

K

= 1.003 ± 0.0001 vs.

vs LHCb’14

SLIDE 62

• 2. LFU test in b → s neutral currents: µ vs. e :
• Compatibility with SM 2.2-2.4σ (low-q2) 2.4-2.5σ (central-q2)

3.2 Lepton universality & NP

62 Emilie Passemar

“RK∗ = Br(B → K ∗µµ)/Br(B → K ∗ee) anomaly”

• S. Bifani, LHCb@CERN’17

SLIDE 63

3.2 Lepton universality & NP

63 Emilie Passemar

SLIDE 64

3.3 Tau LFV

• In New Physics scenarios CLFV can reach observable levels in several channels
• But the sensi*vity of par*cular modes to CLFV couplings is model dependent
• Comparison in muonic and tauonic channels of branching ra*os, conversion rates

and spectra is model-diagnos*c

Emilie Passemar 64

• t
• t
• Talk by D. Hitlin @ CLFV2013

SLIDE 65

2.2 CLFV processes: tau decays

• Several processes:
• 48 LFV modes studied at Belle and BaBar

Emilie Passemar

τ → ℓγ , τ → ℓ α ℓβℓ β , τ → ℓY

P, S, V, PP,...

65

SLIDE 66

2.2 CLFV processes: tau decays

• Several processes:

Emilie Passemar

τ → ℓγ , τ → ℓ α ℓβℓ β , τ → ℓY

P, S, V, PP,...

66

γ

• e

γ

• µ

π

• e

π

• µ

η

• e

η

• µ

' η

• e

' η

• µ

S

K

• e

S

K

• µ

f

• e

f

• µ

ρ

• e

ρ

• µ

K*

• e

K*

• µ

K*

• e

K*

• µ

φ

• e

φ

• µ

ω

• e ω
• µ
• e

+

e

• e
• e

+

e

• µ
• µ

+

µ

• e
• µ

+

µ

• µ
• e

+

µ

• e
• µ

+

e

• µ
• π

+

π

• e
• π

+

π

• µ
• K

+

π

• e
• K

+

π

• µ
• π

+

K

• e
• π

+

K

• µ
• K

+

K

• e
• K

+

K

• µ

S

K

S

K

• e

S

K

S

K

• µ
• π

+

e

• π
• π

+

µ

• π
• K

+

e

• π
• K

+

µ

• π
• K

+

e

• K
• K

+

µ

• K

Λ

• π

Λ

• π Λ
• K

Λ

• K

decays τ 90% C.L. upper limits for LFV

• 10

10

• 9

10

• 8

10

• 7

10

• 6

10

• 5

10

CLEO BaBar Belle LHCb Belle II γ l lP lS lV lll lhh h Λ

• Promising prospects at Belle II!
• P. Urquijo

SLIDE 67

• Build all D>5 LFV operators:

Ø Dipole: Ø Lepton-quark (Scalar, Pseudo-scalar, Vector, Axial-vector): Ø Lepton-gluon (Scalar, Pseudo-scalar): Ø 4 leptons (Scalar, Pseudo-scalar, Vector, Axial-vector):

• Each UV model generates a specific pa\ern of them

2.3 Effective Field Theory approach

Emilie Passemar

L = LSM + C (5) Λ O(5) + Ci

(6)

Λ 2 Oi

(6) i

∑

+ ...

67

See e.g. Black, Han, He, Sher’02 Brignole & Rossi’04 Dassinger et al.’07 Matsuzaki & Sanda’08 Giffels et al.’08 Crivellin, Najjari, Rosiek’13 Petrov & Zhuridov’14 Cirigliano, Celis, E.P.’14

Leff

D ⊃ − CD

Λ 2 mτ µσ µνPL,Rτ Fµν Leff

S ⊃ −

CS,V Λ

2 mτmqGFµ ΓPL,Rτ qΓq

Leff

G ⊃ − CG

Λ

2 mτGFµPL,Rτ Gµν a Ga µν

Leff

4ℓ ⊃ − CS,V 4ℓ

Λ 2 µ ΓPL,Rτ µ ΓPL,Rµ Γ ≡ 1 ,γ µ

SLIDE 68

2.4 Model discriminating power of Tau processes

Emilie Passemar

• Summary table:
• The no*on of “best probe” (process with largest decay rate) is model dependent
• If observed, compare rate of processes key handle on relaLve strength

between operators and hence on the underlying mechanism

τ

68

Celis, Cirigliano, E.P.’14

SLIDE 69

2.6 Model discriminating of BRs

• Studies in specific models

Disentangle the underlying dynamics of NP

Buras et al.’10 ratio LHT MSSM (dipole) MSSM (Higgs) SM4

Br(µ−→e−e+e−) Br(µ→eγ)

0.02. . . 1 ∼ 6 · 10−3 ∼ 6 · 10−3 0.06 . . . 2.2

Br(τ −→e−e+e−) Br(τ→eγ)

0.04. . . 0.4 ∼ 1 · 10−2 ∼ 1 · 10−2 0.07 . . . 2.2

Br(τ −→µ−µ+µ−) Br(τ→µγ)

0.04. . . 0.4 ∼ 2 · 10−3 0.06 . . . 0.1 0.06 . . . 2.2

Br(τ −→e−µ+µ−) Br(τ→eγ)

0.04. . . 0.3 ∼ 2 · 10−3 0.02 . . . 0.04 0.03 . . . 1.3

Br(τ −→µ−e+e−) Br(τ→µγ)

0.04. . . 0.3 ∼ 1 · 10−2 ∼ 1 · 10−2 0.04 . . . 1.4

Br(τ −→e−e+e−) Br(τ −→e−µ+µ−)

0.8. . . 2 ∼ 5 0.3. . . 0.5 1.5 . . . 2.3

Br(τ −→µ−µ+µ−) Br(τ −→µ−e+e−)

0.7. . . 1.6 ∼ 0.2

• 5. . . 10

1.4 . . . 1.7

R(µTi→eTi) Br(µ→eγ)

10−3 . . . 102 ∼ 5 · 10−3 0.08 . . . 0.15 10−12 . . . 26

69 Emilie Passemar

SLIDE 70

Figure 3:

Dalitz plot for τ − → µ−µ+µ− decays when all operators are assumed to vanish with the exception of CDL,DR = 1 (left) and CSLL,SRR = 1 (right), taking Λ = 1 TeV in both cases. Colors denote the density for d2BR/(dm2

µ−µ+dm2 µ−µ−), small values being represented by darker colors and

large values in lighter ones. Here m2

µ−µ+ represents m2 12 or m2 23, defined in Sec. 3.1.

Figure 4:

Dalitz plot for τ − → µ−µ+µ− decays when all operators are assumed to vanish with the exception of CVRL,VLR = 1 (left) and CVLL,VRR = 1 (right), taking Λ = 1 TeV in both cases. Colors are defined as in Fig. 3.

Dassinger, Feldman, Mannel, Turczyk’ 07 Celis, Cirigliano, E.P.’14 Angular analysis with polarized taus

Dassinger, Feldman, Mannel, Turczyk’ 07

70 Emilie Passemar

SLIDE 71

2.7 Model discriminating of Spectra: τ → µ µππ ππ

Leff

D ⊃ − CD

Λ 2 mτ µσ µνPL,Rτ Fµν

Leff

S ⊃ − CS

Λ

2 mτmqGFµPL,Rτ qq

71

Celis, Cirigliano, E.P.’14

Very different distribu*ons according to the final hadronic state!

Leff

G ⊃ − CG

Λ

2 mτGFµPL,Rτ Gµν a Ga µν

NB: See also Dalitz plot analyses for τ → μμμ

Dassinger et al.’07

Emilie Passemar