Celebration of Panofsky Prize

Jonathan Dorfan David Hitlin Fumihiko Takasaki Stephen Olsen

“For leadership in the BaBar and Belle Experiments, which established theviolation of CP symmetry in B-meson decay, and furthered our understanding of

quark mixing and quantum chromodynamics.”

B-factory Science ImpactZoltan Ligeti

Celebration of Dorfan/Hitlin Panofsky Prize

SLAC, January 13, 2016

Personal recollections

• I met Dave when as a postdoc at Caltech (1994–97); was fun to think independentof the available data (then mostly CLEO), imagining the huge future data sets

Some were done by BABAR & Belle: B → Xsγ spectrum and moments, B →Xc`ν moments and |Vcb|, B → Xu`ν hadron mass spectrum, B → D∗∗`ν (LLSW)

Some are still left for the future: B → Xsνν, B → Xcτ ν, etc.

• Discussions with Dave — remember vividly being stunned by deep commentsat a level as if he has been working on the same problem, immediate picture ofdecay properties that he heard about for the first time

• The BABAR workshops took place in my 3rd year at CaltechI went to Rome, Princeton, Paris...

Z L – p. 1

Personal recollections

• I met Dave when as a postdoc at Caltech (1994–97); was fun to think independentof the available data (then mostly CLEO), imagining the huge future data sets

Some were done by BABAR & Belle: B → Xsγ spectrum and moments, B →Xc`ν moments and |Vcb|, B → Xu`ν hadron mass spectrum, B → D∗∗`ν (LLSW)

Some are still left for the future: B → Xsνν, B → Xcτ ν, etc.

• Discussions with Dave — remember vividly being stunned by deep commentsat a level as if he has been working on the same problem, immediate picture ofdecay properties that he heard about for the first time

• The BABAR workshops took place in my 3rd year at CaltechI went to Rome, Princeton, Paris...

• Once, on a weekend, jump-starting Dave’s porschefrom my crappy nissan sentra

Z L – p. 1

Personal recollections

• I met Dave when as a postdoc at Caltech (1994–97); was fun to think independentof the available data (then mostly CLEO), imagining the huge future data sets

Some were done by BABAR & Belle: B → Xsγ spectrum and moments, B →Xc`ν moments and |Vcb|, B → Xu`ν hadron mass spectrum, B → D∗∗`ν (LLSW)

Some are still left for the future: B → Xsνν, B → Xcτ ν, etc.

• Discussions with Dave — remember vividly being stunned by deep commentsat a level as if he has been working on the same problem, immediate picture ofdecay properties that he heard about for the first time

• The BABAR workshops took place in my 3rd year at CaltechI went to Rome, Princeton, Paris...

• Once, on a weekend, jump-starting Dave’s porschefrom my crappy nissan sentra

Z L – p. 1

Summary — version one

• Flavor physics was crucial for the development of the standard model(KL → µµ⇒ GIM, charm; εK ⇒ 3rd generation; ∆mK ⇒mc; ∆mB ⇒heavy mt)

• LEP & SLC in the 90s probed the gauge sectorto better than 1%, testing the theory at one-loop level

Nobel Prize, 1999⇒

• Before 1999, ε was the only unambiguous measurement of CP violationCould be fit with KM phase, but O(1) deviations in SM flavor sector were allowed

• BABAR and Belle probed the Yukawa sector much better

Nobel Prize, 2008⇒

• However, O(20%) BSM contributions to FCNC processesstill allowed — lot of room for Belle II & LHCb to find NP

Z L – p. 2

Large impacts on theory

• Flavor physics triggered lots of developments + testing grounds for new methods

CPV motivated: CP invariance of QCD, isospin & SU(3) flavor, Dalitz analyses

FCNC motivated: Heff at high orders, multi-loop perturbative calculations

Heavy quark symmetry: symmetries, HQET at high orders, many applications

Operator product expansions: Develop / use / test expansions to high orders

Soft-collinear effective theory: Started with B → Xsγ and semileptonic

[Developments continue, expect a lot more, data always motivate theory]

BSM: Hundreds of papers motivated by anomalies, elaboration of MFV, GMSB,other frameworks to address lack of NP signals in flavor [all started pre-BABAR]

• Broad impacts: perturbative / nonperturbative / logs vs fixed order / interfacesBroad impacts: (LHC jet vetos, cross sections, jet substructure, EFT for DM signals, ... )

Z L – p. 3

Rough outline

• B physics before BABAR + progress since

• New measurements at BABAR not done / seen beforeNew measurements at BABAR some impacts constraining BSM

• Future: Belle II, LHCb, current anomalies, prospects

Z L – p. 4

Rough outline

• B physics before BABAR + progress since

• New measurements at BABAR not done / seen beforeNew measurements at BABAR some impacts constraining BSM

• Future: Belle II, LHCb, current anomalies, prospects

Disclaimers

I’ll mostly say BABAR throughout this talk — comparable results from Belle

Focus on topics relevant to understand short-distance physics

Thousands of missing references...

Z L – p. 4

Started before BABAR

Discovery of B0–B0 mixing, 1987

• ARGUS: At much higher rate than expected

• Preceded by: discovery of Υ

Preceded by: long B lifetime

• Flurry of theory papers, SM interpretation:

– Probably mt > mW ⇒ no top hadrons– Expect Bs mixing near maximal

• SM predicts large CP violationSM predicts large FCNC B decay rates

Z L – p. 5

Resolving Bs oscillations: CDF, 2006

• Current world averages:

∆md = (0.5055± 0.0020) ps−1 0.4% precision

∆ms = (17.757± 0.021) ps−1 0.1% precision

(Both dominated by LHCb now)

• ∆ms more precise, frequency measurement...

decay time [ps]0 1 2 3 4

can

did

ates

/ (

0.1

ps)

0

200

400

Tagged mixed

Tagged unmixed

Fit mixed

Fit unmixed

LHCb

Z L – p. 6

B lifetime, Vcb — the beginning

• 1983: Long B meson lifetime⇒ |Vcb| is small

(Panofsky prize 2006)

• ARGUS: oscillation & decay timescale comparable: ∆m/Γ ' 0.77 (and ∆Γ� Γ)

• Crucial to allow experimental study of CP violation in B system

• If |Vcb| were as large as |Vus|, probably BABAR & Belle would not have been built

No precision CKM tests? no KM Nobel Prize?

Z L – p. 7

Vub — the beginning

ARGUS, PLB 234 (1990) 409, Received 28 Nov 1989 (201+69 pb−1)

“If interpreted as a signal of b → u cou-pling . . . |Vub/Vcb| of about 10%.”

CLEO, PRL 64 (1990) 16, Received 8 Nov 1989 (212+101 pb−1)

“|Vub/Vcb| . . . is approximately 0.1; itis sensitive to the theoretical model.”

Z L – p. 8

Vcb and Vub since...

• PDG 1988: |Vcb| = 0.046± 0.010, |Vub/Vcb| < 0.2

• Huge experimental and theoretical efforts since late 1980s

• |Vub|: If it were 0, no CP violation in CKM matrix

|Vub|: Dominant uncertainty of the side of the UT opposite to β

|Vub|: Crucial for NP sensitivity (compare “tree” and “loop” constraints)

• |Vcb|: Large part of the uncertainty in the εK constraint

|Vcb|: Large part of the uncertainty in B(K → πνν)

• Same theoretical tools as for inclusive and exclusive rare b → sγ, b → s `+`−,b→ sνν decays, which are sensitive probes of NP

Z L – p. 9

|Vcb| alone excluded GUT models / textures

B → K∗γ and B → Xsγ before BABAR

• CLEO discovered radiative B decays — only bounds on B → K∗`+`− & Xs`+`−

• Series of elaborate calculations of FCNC B decays started about ’87

• Surprisinglyprecise!

Z L – p. 10

B → Xsγ now

• One (if not “the”) most elaborate SM calculationsConstrains many models: 2HDM, SUSY, LRSM, etc.

• NNLO practically completed [Misiak et al., 1503.01789]

4-loop running, 3-loop matching and matrix elements

Scale dependencies significantly reduced ⇒

• B(B → Xsγ)∣∣Eγ>1.6GeV

= (3.36± 0.23)× 10−4

Measurement: (3.43± 0.22)× 10−4

O(104) diagrams, e.g.:

b s

c

c

γ

�

Z L – p. 10

PEP-II and BABAR

Asymmetry is a key to time-dependent measurements

(P. Oddone, Panofsky prize 2005)

The Machine

(APIARY is no more contrived than BaBar for B and B-bar Experiement)

The Physics

[No...][No...]

The BABAR Physics Book

• No executive summary, neither a list of killer apps or gold-plated measurements...

• Serves now as a model for the Belle II Theory Interface Platform

Z L – p. 13

Cites > 500

↑ Unexpected

↓ Expected

CP violation — views around 1999

• Until 1999, ε was the only measured CPV, ε′/ε unambiguously measured in ’99

The SM with 3-generationscould accommodate ε, but ...

[Y. Nir]

• Are there detectable new particles / interactions, which couple to flavor?

Z L – p. 15

Questions around 1999

• Is the SM the only source of CPV? Does the SM fully explain flavor physics?

– CPV in ∆F = 2 only (superweak)? Also in ∆F = 1?

– Are all CPV effects small? Or only small in kaons due to small mixing angles?

– One or more CPV parameters?

– CPV relates to charged currents only? Also in neutral currents?

– Does CPV treat 3rd generation special? Up / down sectors?

– CPV in flavor changing interactions only? EDM searches?

– CPV only in quark sector? Also in lepton sector?

– Find new sources of CPV that could help with baryogenesis?

• It was not known if the SM picture of CPV was even approximately correct

Z L – p. 16

Views of FCNCs around 1999

• Many models with SM-like 1st and 2nd generations, while 3rd is different

• The very high scale sensi-tivity of neutral meson mixingwas known since the 70s

[M. Wise]

While publicity of BABAR relied on CPV, to test the SM, no deep distinction (argM12 or |M12|...)

Z L – p. 17

BABAR novelties

Quantum entanglement in Υ(4S)→ B0B0

• B0B0 pair created in a p-wave (L = 1) evolve coherently and undergo oscillations

Two identical bosons cannot be in an antisymmetric state — if one B decays asa B0 (B0), then at the same time the other B must be B0 (B0)

• EPR effect used for precision physics:

Measure B decays and ∆z

• First decay ends quantum correlation and tags the flavor of the other B at t = t1

Z L – p. 18

One of the cleanest cases: CPV in B → ψKS

• CP violation can be an O(1) effect: sin 2β = 0.691± 0.017

afCP =Γ[B

0(t)→ ψK]− Γ[B

0(t)→ ψK]

Γ[B0(t)→ ψK] + Γ[B

0(t)→ ψK]

= sin 2β sin(∆mt)

0B

0B

CPf

q/p

A

A

b

d

d

b

t

t

W W

b

d

d

b

W

W

t t

• CP violation is large in some B decays — it is small in K decays due to smallCKM elements, not because CP violation is generically small

Z L – p. 19

sin 2β in “penguin modes”

• Huge stakes: robust deviation from expectations would indicate new physics

• Proliferation ofblind analyses...

[ c© Hitlin @ ICHEP 2000]

MeasuringCP violation is no longer auto-

matically interesting — If Sη′K were near

0, we’d have a many σ discovery of NP!

• Some of these measurements willget near current sin 2β levels

sin(2βeff

) ≡ sin(2φe1ff) vs C

CP ≡ -A

CP

Contours give -2∆(ln L) = ∆χ2 = 1, corresponding to 60.7% CL for 2 dof

-0 0.2 0.4 0.6 0.8 1

-0.4

-0.2

0

0.2

0.4

sin(2βeff

) ≡ sin(2φe1ff)

CCP ≡ -ACP

b→ccs

φ K0

η′ K0

KS K

S K

S

π0 K

S

ρ0 K

S

ω KS

f0 K

0

K+ K

- K

0

H F A GH F A GMoriond 2014

PRELIMINARY

Z L – p. 20

Beyond expectations: α and γ

• ’97 CLEO: B(B → Kπ) > B(B → ππ)⇒ |P/T | >∼ 0.3

Isospin analysis to isolate CPV in ππI=2 state (tree)

• Sometimes lucky with hadronic physics:B(B→ρ0ρ0)B(B→ρ+ρ0)

≈ 0.03 vs. B(B→π0π0)B(B→π+π0)

≈ 0.23

Largest BABAR / Belle difference? (deg)α

0 20 40 60 80 100 120 140 160 180

p­v

alu

e

0.0

0.2

0.4

0.6

0.8

1.0

EPS 15

CKMf i t t e r

(WA)ρρ→B

(WA)ππ→B

(WA)πρ→B

Combined

CKM fit

• γ: interfere b→ cus (B− → D0K−) withγ: interfere b→ ucs (B− → D0K−)

Problem: small ratio, rB = |A(B−→D0K−)||A(B−→D0K−)| ≈ 0.1

• Most precise: D0, D0 → KS π+π−

Both amplitudes CA; integrate over Dalitz plotγ

0 20 40 60 80 100 120 140 160 180

p­v

alu

e

0.0

0.2

0.4

0.6

0.8

1.0

CKM 14

CKMf i t t e r

GLW+ADS

GGSZ

Combined

• Tree-level phase information — became interesting ’03–04 [Richman, Physics Coordinator]

Z L – p. 21

Direct CPV is also O(1)

• Have we seen new physics in CPV?

AK+π− = −0.082± 0.006 (P + T )

AK+π0 = 0.040±0.021 (P+T+C+A+Pew)

• Large difference — small SM sources?

AK+π0 −AK+π− = 0.122± 0.022

(T ) (P )

(C) (Pew)

(Annihilation not shown) [Belle, Nature 452, 332 (2008)]

SCET / factorization predicts: arg (C/T ) = O(ΛQCD/mb) and A+ Pew small

• Large fluctuations? Breakdown of 1/m exp.? Missing something subtle? BSM?

• Can we understand theory well enough, to possibly disprove SM?

• Even larger ACP (Bs → π+K−) = 0.27± 0.04 understood in terms of SU(3)[Grossman, ZL, Robinson, 1308.4143]

Z L – p. 22

D0 –D0 mixing only established in 2007

• Complementary to K, B, Bs

Mixing generated by down quarksor in SUSY by up-type squarks

• Value of ∆m? Not even 2σ now!

Bounds on |q/p| − 1 fairly weakx (%)

−0.6 −0.4 −0.2 0 0.2 0.4 0.6 0.8 1 1.2

y (

%)

−0.6

−0.4

−0.2

0

0.2

0.4

0.6

0.8

1

1.2CPV allowed

σ 1

σ 2

σ 3

σ 4

σ 5

HFAG-charm

CHARM 2015

|q/p|

0.6 0.8 1 1.2 1.4 1.6

Arg

(q/p

) [d

eg

.]

−60

−40

−20

0

20

40

60

σ 1

σ 2

σ 3

σ 4

σ 5

HFAG-charm

CHARM 2015

•SM

•no mixing

• Measurements will remain interesting in the next decade

SUSY: interplay with LHC searches (required degeneracy of squarks)

• Direct CPV: ∆ACP ≡ AK+K− −Aπ+π− = −(8.2± 2.4)× 10−3 (LHCb, 2011)

Current WA: ∆ACP = −(2.5± 1.0)× 10−3 ↖(a stretch in the SM, imho)

• I think we still don’t know how big an effect could (not) be accommodated in SM

Z L – p. 23

Very broad program

• Many fascinating topics I cannot talk about — hundreds of papers on each:

– B → K(∗)`+`− and B → Xs`+`−: first observations to good precision

– Search for decays violating conservation laws

– Search for invisible modes

– Hidden sector searches

– New hadronic states

Z L – p. 24

Very broad program

• Many fascinating topics I cannot talk about — hundreds of papers on each:

– B → K(∗)`+`− and B → Xs`+`−: first observations to good precision

– Search for decays violating conservation laws

– Search for invisible modes

– Hidden sector searches

– New hadronic states

I do not know how many CP violating quantities have been measured, neitherhow many new hadronic states discovered / seen by BABAR

Anyone...?

Z L – p. 24

Putting it all together: the SM CKM fit

• Huge progress compared to pre-BABAR

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1ρ_

η_

(BABAR Physics Book, 1998, p.957)

γ

γ

α

α

dm∆

Kε

Kε

sm∆ & dm∆

ubV

βsin 2

(excl. at CL > 0.95)

< 0βsol. w/ cos 2

exc

luded a

t CL >

0.9

5

α

βγ

ρ

­1.0 ­0.5 0.0 0.5 1.0 1.5 2.0η

­1.5

­1.0

­0.5

0.0

0.5

1.0

1.5

excluded area has CL > 0.95

EPS 15

CKMf i t t e r

• KM phase is the dominant source of CPV in flavor changing transitions of quarks

Z L – p. 25

Nobel Prize 2008

• Before BABAR we did not know that the CKMpicture was (essentially) correct

O(1) deviations in CP violation were possible

• Nobel Prize is formal recognition that the KMphase is established as the dominant sourceof CPV in flavor changing transitions of quarks

• Confirmation of the SM ⇒ looking for corrections to the SM

• Future: What can flavor physics teach us about beyond SM physics?

Z L – p. 26

New physics in meson mixing

• Meson mixing:

Meson mixing:

Simple parametrization:M12 = MSM

12 (1+he2iσ)

SM: CSM

m2W

NP: CNP

Λ2

What is the scale Λ? How different is CNP from CSM?

If deviation from SM seen⇒ upper bound on Λ

• Assume: (i) 3× 3 CKM matrix is unitaryAssume: (ii) tree-level decays dominated by SM

• Mature topic, conservative picture of future progress

Z L – p. 27

The CKM fit with NP allowed in mixing

• Allowed ρ– η region becomes much larger: [1309.2293]

2003 2013 LHCb 50/fb + Belle II 50/ab

ubV

α

βγ

ρ

­1.0 ­0.5 0.0 0.5 1.0 1.5 2.0

η

­1.5

­1.0

­0.5

0.0

0.5

1.0

1.5

excluded area has CL > 0.95

2003

CKMf i t t e r γ

γ

)α(γ

)α(γ

ubV

ubV) & α(γ & γ

α

βγ

ρ

­1.0 ­0.5 0.0 0.5 1.0 1.5 2.0

η

­1.5

­1.0

­0.5

0.0

0.5

1.0

1.5

excluded area has CL > 0.95

2013

CKMf i t t e r

)_(a

)_(a

a

a

ubV

ubV) & _(a & a

_

`a

l

-1.0 -0.5 0.0 0.5 1.0 1.5 2.0

d

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

excluded area has CL > 0.95

Stage II

CKMf i t t e r

_

0.05 0.10 0.15 0.20 0.250.25

0.30

0.35

0.40

0.45

Tree-level constraints unaffected, loop-dominated observables sensitive to NP

• Tree-level measurements (Vub, γ) crucial to isolate new physics contributions

Z L – p. 28

New physics in B0d mixing

2003 Now LHCb 50/fb + Belle II 50/ab

dh0.0 0.5 1.0 1.5 2.0 2.5 3.0

dσ

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0p­value

excluded area has CL > 0.95

2003

CKMf i t t e r

dh0.0 0.1 0.2 0.3 0.4 0.5

dσ

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0p­value

excluded area has CL > 0.95

2013

CKMf i t t e r

HFAG 2014s

φ

dh0.0 0.1 0.2 0.3 0.4 0.5

dσ

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0p­value

excluded area has CL > 0.95

Stage II

CKMf i t t e r

[color: 2σ, dotted: 3σ] M(d)12 = MSM

12 × (1 + hd e2iσd) [1309.2293]

NP <∼ (many×SM) → NP <∼ (0.3 × SM) → NP <∼ (0.05 × SM)

h '|Cij|2

|V ∗ti Vtj|2

(4.5 TeV

Λ

)2

— will reach: Λ ∼

{2.3× 103 TeV

20 TeV (tree + CKM)2 TeV (loop + CKM)

• Right sensitivity to be in the ballpark of gluino masses explored at LHC14

Z L – p. 29

Sensitivity to NP in B0d and B0

s mixing

2003 Now LHCb 50/fb + Belle II 50/ab

dh0.0 0.5 1.0 1.5 2.0 2.5 3.0

sh

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0p­value

excluded area has CL > 0.95

2003

CKMf i t t e r

dh0.0 0.1 0.2 0.3 0.4 0.5

sh

0.0

0.1

0.2

0.3

0.4

0.5

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0p­value

excluded area has CL > 0.95

2013

CKMf i t t e r

HFAG 2014s

φ

dh0.0 0.1 0.2 0.3 0.4 0.5

sh

0.0

0.1

0.2

0.3

0.4

0.5

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0p­value

excluded area has CL > 0.95

Stage II

CKMf i t t e r

[color: 2σ, dotted: 3σ] M(q)12 = MSM

12 × (1 + hq e2iσq) [1309.2293]

NP <∼ (many×SM) → NP <∼ (0.3 × SM) → NP < (0.05 × SM)

Sensitivity caught up with that in Bd mixing, and will improve comparably

• MFV and non-MFV regions will have comparable constraints (unlike in the past)

Z L – p. 30

Future

Missed opportunity

• Dave and I were in the small minority convinced >10 yearsago that a super B factory at SLAC should be a part of ahealthy US HEP program

(My first super-BABAR talk in 2001, Dave’s probably 1–2 years earlier)

• “Lower bound” on future progress (only statistics improvements, maximally conservative)

(2009 BABAR data set)(1999 CLEO data set)

∼(Belle II data set)(Belle data set)

∼(LHCb upgrade)

(LHCb 1 fb−1)∼ 50

Increase in sensitivity to high scales 4√

50 ∼ 2.5, similar to LHC 7-8→ LHC 13-14(Expect unexpected progress — data has always motivated new ideas)

Z L – p. 31

Questions for the future

• Will LHC see new particles beyond the Higgs?SUSY, something else, understand in detail?

• Will NP be seen in the quark sector?

Near future: current anomalies have the largestchance to become significant

Several hints of lepton flavor universality violation

With 50/fb LHCb and 50/ab Belle II data,large discovery potential in many modes

• Will NP be seen in the lepton sector (CLFV)?µ→ eγ, µ→ eee, τ → µγ, τ → µµµ, ...?

Current flavor anomalies

1 2 3 4

significance (σ)

f(t

heo

reti

cal

clea

nlin

ess)

h→τμ

B→Ke+e-/B→Kμ+μ-

D0 μμ CP asym

B→D(*)τνBd→μμ

B→K *μ+μ- angular

Bs→ϕμ+μ-

|Vcb| incl/excl

|Vub| incl/excl

g-2

ϵ'/ϵ

• No one knows — that’s why it’s research...

Z L – p. 32

The B → D(∗)τ ν story: ∼4σ

• Belle & LHCb results on the anomaly seen by BABAR in R(X) =Γ(B → Xτν)

Γ(B → X(e/µ)ν)

R(D) R(D∗)

BABAR 0.440± 0.058± 0.042 0.332± 0.024± 0.018

Belle 0.375± 0.064± 0.026 0.293± 0.038± 0.015

LHCb 0.336± 0.027± 0.030

Average 0.391± 0.050 0.322± 0.022

SM expectation 0.300± 0.010 0.252± 0.005

Belle II, 50/ab ±0.010 ±0.005R(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

0.5BaBar, PRL109,101802(2012)Belle, arXiv:1507.03233LHCb, arXiv:1506.08614Average

= 1.02χ∆

SM prediction

HFAG

EPS 2015

) = 55%2χP(

HFAG

Prel. EPS2015

SM predictions fairly robust: heavy quark symmetry + lattice QCD for R(D) [1503.07237, 1505.03925]

• Tension: R(D(∗)) vs. B(b→ Xτ+ν) = (2.41± 0.23)% (LEP) [ZL, Tackmann]

Tension: SM predicts R(Xc) = 0.223± 0.004 — precisely [Freytsis, ZL, Ruderman]

Need NP at fairly low scales (leptoquarks, W ′, etc.), likely visible in LHC Run 2

• Soon: LHCb result with hadronic τ decays, measure R(D), maybe Λb decay

Z L – p. 33

What are the largest useful data sets?

• Which measurements will remain far from being limited by theory uncertainties?

– For γ ≡ φ3, theory limit only from higher order electroweak

– Bs,d → µµ, B → µν and other leptonic decays (lattice QCD, [double] ratios)

– Probably CP violation in D mixing (firm up theory)

– Ad,sSL (can get around exp. syst. limits?)

– CLFV, EDM, etc.

• Crude guess: until∼102× Belle II & LHCb upgrade data, sensitivity to high scaleswould improve

• In some decay modes, even in 2030 we’ll have: (exp. bound)/

SM >∼ 103

E.g., B → τ+τ−, e+e− — can build models... I hope to be wrong!

Z L – p. 34

Conclusions — have come a long way

• Flavor physics probes scales�1 TeV; sensitivity limited by statistics, not theory

• New physics in most FCNC processes may still be ∼ 20% of the SM, or more

• Few tensions with the SM; some of these (or others) may become decisive

• Precision tests of SM will improve by 101 – 104 in many channels (CLFV)

I think Mu2e is fantastic — good luck, Dave!

• Many interesting theoretical questions, relevant for experimental sensitivity

• I cannot imagine a scenario in which there is no complementarity between flavorand LHC searches of new physics, and hopefully understanding it

Z L – p. 35

Bonusl slides

The big question: where is new physics?

1 3 5 7 9 11 13 15 17

Tevatron

proton decay

flavor (quarks)

Experimental reach (with significant simplifying assumptions)

log(Energy[GeV])

LHC

dark matter

mu to e

neutrino propertiesE

WS

B

see−

saw

GU

T

Pla

nck

Dashed arrows show anticipated improvements in next generation of experiments

– Proton decay already ruled out simplest version of grand unification

– Neutrino experiments hope to probe see-saw mechanism

– Flavor physics probes TeV-scale new physics with even SM-like suppressions

– LHC was in a unique situation that a discovery was virtually guaranteed (known since 80’s)

Z L – p. i

Push Bs,d→ µ+µ− to theory limit

• For Bd, CMS (LHCb) expect ultimately 15–20% (30–40%) precision at SM level

SM uncertainty ' (2%)⊕ f2Bq⊕ CKM [Bobeth, FPCP’15]

]9−[10)−µ+µ→0BB(0 0.2 0.4 0.6 0.8

LlnΔ2−

0

2

4

6

8

10SM

]9−[10)−µ+µ→s0BB(

0 2 4 6 8

LlnΔ2−

0

10

20

30

40SM

]9−[10)−µ+µ→s0BB(

0 1 2 3 4 5 6 7 8 9

]9−[1

0)− µ

+ µ→

0B

B(

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

68.27%

95.45%

99.73% 5−10

×6.3

−1

7−10

×5.7

−1

9−10

×2−1

SM

CMS and LHCb (LHC run I)

a

b

c

[LHCb & CMS, 1411.4413]

• Theoretically cleanest |Vub| I know, only isospin: B(Bu → `ν)/B(Bd → µ+µ−)

• A decay with mass-scale sensitivity (dim.-6 operator) that competes w/ K → πνν

Z L – p. ii

Bound on vector-like fermions

• Do not make hierarchy problem worse; vector-like fermions can Yukawa couple tothe SM fermions via the Higgs in 11 models (⇒ FCNC Z couplings) [Ishiwata, ZL, Wise]

ModelQuantum Present bounds on M/TeV and λiλj for each ij pair

numbers ij = 12 ij = 13 ij = 23

I (1, 1,−1) 310a 7.0b 7.4c

II (1, 3,−1) 220a 4.9b 5.2c

III (1, 2,−1/2) 310a 7.0b 7.4c

IV (1, 2,−3/2) 310a 7.0b 7.4c

∆F = 1 ∆F = 2 ∆F = 1 ∆F = 2 ∆F = 1 ∆F = 2

V (3, 1,−1/3) 66d [100]e {42, 670}f 30g 25h 21i 6.4j

VI (3, 1, 2/3) 3.9k {42, 670}f — 25h — 6.4j

VII (3, 3,−1/3) 47d [71]e {47, 750}f 21g 28h 15i 7.2j

VIII (3, 3, 2/3) 66d [100]e {47, 750}f 30g 28h 21i 7.2j

IX λ(u)}(3, 2, 1/6)

3.9k 67l — 35h — 9.1j

IX λ(d) 66d [100]e {59, 950}f 30g 35h 18m 9.1j

X (3, 2, 7/6) 3.9k 48l — — — —

XI (3, 2− 5/6) 66d [100]e {42, 670}f 30g 25h 18m 6.4j

Strongest bounds from large variety of processes: a) µ to e conversion; b) τ → eπ; c) τ → µρ; d) K → πνν; e) KL →

µ+µ−; f)K mixing; g)B → πµ+µ−; h)Bd mixing; i)B → Xs`+`−; j)Bs mixing; k)D → µ+µ−; l)Dmixing;m)Bs → µ+µ−

Z L – p. iii

Vector-like fermions — future bounds

• Planned experiments increase sensitivity in mass scales by factors of 2.5− 7

ModelQuantum Future bounds on M/TeV and λiλj for each ij pair

numbers ij = 12 ij = 13 ij = 23

I (1, 1,−1) 2000a 19b 21c

II (1, 3,−1) 1400a 13b 15c

III (1, 2,−1/2) 2000a 19b 21c

IV (1, 2,−3/2) 2000a 19b 21c

∆F = 1 ∆F = 2 ∆F = 1 ∆F = 2 ∆F = 1 ∆F = 2

V (3, 1,−1/3) 280d {100, 1000}e 60f 61g 39h 14i

VI (3, 1, 2/3) 8.3j {100, 1000}e — 61g — 14i

VII (3, 3,−1/3) 200d {110, 1100}e 42f 68g 28h 16i

VIII (3, 3, 2/3) 280d {110, 1100}e 60f 68g 39h 16i

IX λ(u)}(3, 2, 1/6)

8.3j 67k — 86g — 20i

IX λ(d) 280d {140, 1400}e 60f 86g 39h 20i

X (3, 2, 7/6) 8.3j 48k — — — —

XI (3, 2− 5/6) 280d {100, 1000}e 60f 61g 39h 14i

Expected best sensitivity from large variety of processes: a) µ to e conversion; b) τ → eπ; c) τ → µρ; d) K → πνν; e) K

mixing; f) Bd → µ+µ−; g) Bd mixing; h) Bs → µ+µ−; i) Bs mixing; j) D → µ+µ−; k) D mixing.

Z L – p. iv

A super-B best buy list

• Want observables: (i) sensitive to different NP, (ii) measurements can improve byan order of magnitude, and (iii) not limited by hadronic uncertainties:

• Difference of CP asymmetries, SψKS − SφKS• γ from CP asymmetries in tree-level decays vs. γ from SψKS and ∆md/∆ms

• Search for charged lepton flavor violation, τ → µγ, τ → 3µ, and similar modes

• Search for CP violation in D0 −D0 mixing

• The CP asymmetry in semileptonic decay, ASL

• The CP asymmetry in the radiative decay, SK∗γ

• Search for not yet seen FCNC decays and refinements: b→ sνν, B → τ ν, etc.

• Any one of these measurements has the potential to establish new physics

Z L – p. v

Some theory challenges

• New methods & ideas: recall that the best α and γ measurements are in modesproposed in light of Belle & BABAR data (i.e., not in the BABAR Physics Book)

– Better SM upper bounds on Sη′KS − SψKS, SφKS − SψKS, and Sπ0KS− SψKS

– (and similarly in Bs decays)

– How big can CP violation be in D0 –D0 mixing (and in D decays) in the SM?

– Better understanding of semileptonic form factors; bound on SKSπ0γ in SM?

– Inclusive & exclusive semileptonic decays

– Many lattice QCD calculations (operators within and beyond SM)

– Factorization at subleading order (different approaches), charm loops

– Can direct CP asymmetries in nonleptonic modes be understood enough to– make them “discovery modes”? [SU(3), the heavy quark limit, etc.]

• We know how to make progress on some + discover new frameworks / methods?

Z L – p. vi

Charged lepton flavor violation

• SM predicted lepton flavor conservation with mν = 0

Given mν 6= 0, no reason to impose it as a symmetry

• If new TeV-scale particles carry lepton number(e.g., sleptons), then they have their own mixingmatrices⇒ charged lepton flavor violation

• Many interesting processes:µ→ eγ, µ→ eee, µ+N → e+N (′), µ+e− → µ−e+

τ → µγ, τ → eγ, τ → µµµ, τ → eee, τ → µµe

τ → µee, τ → µπ, τ → eπ, τ → µKS, eN → τN

B(µ→ eγ) ∼ αm4ν

m4W

∼ 10−52

1940 1950 1960 1970 1980 1990 2000 2010 2020 2030

-1910

-1710

-1510

-1310

-1110

-910

-710

-510

-310

-110

1

• Next 10–20 years: 102–105 improvement; any signal would trigger broad program

Z L – p. vii

Electric dipole moments and SUSY

• SM + mν: CPV can occur in: (i) quark mixing; (ii) lepton mixing; and (iii) θQCD

Only observed δKM 6= 0, baryogenesis implies there must be more

• Neutron EDM bound: “The strong CP problem”, θQCD < 10−10 — axion?θQCD is negligible for CPV in flavor-changing processes

• EDMs from CKM: vanish at one- and two-loopEDMs from CKM: large suppression at three-loop level

• E.g., SUSY: quark and lepton EDMs can be generated at one-loop

Generic prediction (TeV-scale, no small param’s) above cur-rent bounds; if mSUSY ∼ O(10 TeV), may still discover EDMs

• Expected 102–103 improvements: complementary to LHCDiscovery would give (rough) upper bound on NP scale

Z L – p. viii

LBL Contributions

ConceptionDesign

Fabrication

CommissioningOperations/Calibration

Reco/Simulation

Analysis

upgrade

LBNL BaBar:

Doing the Physics from Start to Finish

B→VV

B→φK

B→Ds π

B→ρπ

CPT,∆Γ

New computing model

Alignment

Trigger

DIRC

SVT

P. Oddone, Panofsky prize 2005

c© R. Cahn