From B-meson Factories tothe Large Hadron Collider

Zoltan LigetiCincinnati, March 31, 2011

Some friends’ comments about giving such a colloquium (paraphrased):

“It’s very difficult, what do you even try to talk about?”

“I decided never to give a colloquium on B physics, it’s impossible to explain”

– The interesting messages are not easy to explain– Not just one, single, critical measurement; theory often complicated

– What is easy to explain, is not that interesting– Any one measurement alone is much less powerful than all data combined

What I shall try to explain:

If the LHC is to discover beyond SM physics, it’s nontrivial why it hasn’t shown up

However, 20% new contribution to most loop-dominated processes still allowed

Many possible synergies about what we’ll learn at LHC and in flavor experiments

p.1

Preliminaries

Units: h = c = 1

[energy] [momentum] 1

[time]

1

[length]

1GeV proton mass 1

6:6 1025 sec

1

2 1016m

1:8 1024 g

p.2

Preliminaries

Units: h = c = 1

[energy] [momentum] 1

[time]

1

[length]

1GeV proton mass 1

6:6 1025 sec

1

2 1016m

1:8 1024 g

1:1 1057M 1

2:1 1032 yr

1

6:5 1033 pc

p.2

Preliminaries

Units: h = c = 1

[energy] [momentum] 1

[time]

1

[length]

1GeV proton mass 1

6:6 1025 sec

1

2 1016m

1:8 1024 g

1:1 1057M 1

2:1 1032 yr

1

6:5 1033 pc

Players: B-factories: ee+ colliders at Ecm 10:5GeV

Players: Tevatron: pp collider at Ecm 2TeV = 2 103GeV

Players: LHC: pp collider at Ecm 7 (! :::?)! 14 (13?)TeV [ 1020m]

p.2

What is particle physics?

Central question of particle physics:

L = ?

... What are the elementary degrees of freedom and how do they interact?

p.3

What is particle physics?

Central question of particle physics:

L = ?

... What are the elementary degrees of freedom and how do they interact?

Most experimentally observed phenomena consistent with standard model (SM)

p.3

What is particle physics?

Central question of particle physics:

L = ?

... What are the elementary degrees of freedom and how do they interact?

Most experimentally observed phenomena consistent with standard model (SM)

Clearest empirical evidence that SM is incomplete:

– Dark matter Maybe at

– Baryon asymmetry of the Universe the TeV

– Hierarchy problem [is there an elementary Higgs? why so light?] scale?

– Neutrino mass [can add in a straightforward way]

– Dark energy [cosmological constant? need to know more to understand?]

p.3

The Universe: what is dark matter (DM)?

Homogeneous, isotropic, spatially flat, expanding

Dark matter: rotation curves, gravitational lensing, cosmology

We know that DM is not a particle we know:Know: non-baryonic, long lived, neutral, abundanceDon’t know: interactions, mass, quantum numbers, one/many species

Maybe thermal relic of early universe: weakly interacting massive particle (WIMP)

If so, WIMP mass has to be around the TeV scale — LHC may directly produce it

p.4

The Universe: matter vs. antimatter

Gravity, electromagnetism, strong interaction are same for matter and antimatter

Soon after the big bang, quarks and anti-quarks were in thermal equilibrium

N(baryon)N(photon)

109 )Nq NqNq +Nq

109

at t < 106 s (T > 1GeV)

The SM prediction is 1010 times smaller

Solution may lie at the TeV scale, and the LHC may shed light on it

p.5

The matter–antimatter asymmetry

How could the asymmetry be generated dynamically?

Sakharov conditions (1967):

1. baryon number violating interactions

2. C and CP violation

3. deviation from thermal equilibrium

SM contains 1–3, but:

i. CP violation is too small

ii. deviation from thermal equilibrium too small at electroweak phase transition

New TeV-scale physics can enhance both (supersymmetry, 4th generation, etc.)

What is the microscopic theory of CP violation? How precisely can we test it?

p.6

Outline

Physics beyond the SM must exist, good reasons to hope it’s at the TeV scale

If the LHC discovers new physics, nontrivial why no sign of it has been seen yet... Hitchhiker’s guide to the standard model (SM)... What is flavor physics and why you might care?

Looking for new physics (NP) with B decays... Many precise measurements (CP violation and other)... Sizable non-SM contributions still possible

Flavor physics in the LHC era... b and t measurements... New physics with new flavor

Conclusions

p.7

Ancient past

The crucial role of symmetries: C, P , and T

C = charge conjugation (particle $ antiparticle)

P = parity (~x$ ~x)

T = time reversal (t$ t, initial $ final states)

CPT cannot be violated in a relativistically covariant local quantum field theory

p.8

The crucial role of symmetries: C, P , and T

C = charge conjugation (particle $ antiparticle)

P = parity (~x$ ~x)

T = time reversal (t$ t, initial $ final states)

CPT cannot be violated in a relativistically covariant local quantum field theory

Once upon a time, “Tau – Theta puzzle”: + ! +0

Once upon a time, “Tau – Theta puzzle”: + ! ++ : JP = 0

If parity is conserved in decay: P () = (1)J(+) and P () = (1)J(

+)

Assumed: + 6= + but by 1955 precise mass & lifetime measurements (now: K+)

Lee and Yang: test if weak interactions violate parity? (Nobel prize, 1957)

) Modern theory of weak interactions

p.8

The crucial role of symmetries: C, P , and T

C = charge conjugation (particle $ antiparticle)

P = parity (~x$ ~x)

T = time reversal (t$ t, initial $ final states)

CPT cannot be violated in a relativistically covariant local quantum field theory

Charge & angular momentum: 4 possibilities

Only L and R participate in weak interaction

Weak interaction maximally violates C and P

CP was still assumed to be a good symmetry

p.8

The crucial role of symmetries: C, P , and T

C = charge conjugation (particle $ antiparticle)

P = parity (~x$ ~x)

T = time reversal (t$ t, initial $ final states)

CPT cannot be violated in a relativistically covariant local quantum field theory

Charge & angular momentum: 4 possibilities

Only L and R participate in weak interaction

Weak interactions maximally violate C and P

However, CP could still be a good symmetry

p.8

The CP symmetry is also broken

Still, CP was expected to be unbroken

Two neutral states, almost equal mass,but lifetime ratio > 500

If CP conserved, CP = 1 eigenstates: 1p2

jK0i jK0i

in J = 0 state has CP = +1, so only one of the states can decay to it

Discovered in 1964:(0:2%) (Nobel prize, 1980)

A new CP violating interaction? Is CP an (approximate) symmetry?[Before charm and much of the SM — could involve new particles / new sectors of the theory]

Many options... No other independent observation of CP violation until 1999

p.9

Telling matter from anti-matter

Can “define” matter: e.g., larger probability for KL ! e+ than KL ! e decay

Can “define” matter: (K0L ! e+ +X) > (K0

L ! e +X)

Matter and antimatter are distinguishable due to CP violation

“Practical” question solved by CP viol.

Can tell if spaceship is made of matteror anti-matter... to avoid annihilation

p.10

Hitchhiker’s guide to the SM

Standard model tidbits

Particle content:

3 generations of fermions

Gauge symmetry — forces:

SU(3)c SU(2)L U(1)Y

Symmetry breaking:

SU(2)LU(1)Y ! U(1)EM [WIKIPEDIA]

p.11

Standard model tidbits

Particle content:

3 generations of fermions

Gauge symmetry — forces:

SU(3)c SU(2)L U(1)Y

Symmetry breaking:

SU(2)LU(1)Y ! U(1)EM

me;m;m mu;mc;mt

md;ms;mb

1;2;3;

p.11

Standard model tidbits

Particle content:

3 generations of fermions

Gauge symmetry — forces:

SU(3)c SU(2)L U(1)Y

Symmetry breaking:

SU(2)LU(1)Y ! U(1)EM

me;m;m mu;mc;mt

md;ms;mb

1;2;3;

Strongly interacting particles seen in Nature have no color — quarks confinedmesons: + (u d); K0 (sd); B0 (bd); B0

s (bs); baryons: p (uud); n (udd)

p.11

The missing piece: Higgs boson

Electroweak precision measurements ) mH < 200GeV in the SM

The LHC will study the Higgs (or some-thing else) responsible for the symmetrybreaking — has to be below 1TeV

(No spin-0 elementary particle is known yet)

Don’t understand masses: couplings to H

p.12

The identities of quarks

Hamiltonian ) eigenstates, eigenenergies

Degeneracy = unresolved ambiguity in naming things

– degeneracy broken by perturbations ) “good” states– degeneracy unbroken ) symmetry?

Some perturbations break degeneracies and assign identities

The quantum numbers of u; c; t are identical (so are those of d; s; b)

Degeneracy under choosing “good” combinations: eqi =Pj Uij qj

Ambiguity in assigning identities to particles: are qi or eqi fundamental?

Degeneracy broken by quark masses — where do they come from?

Only known difference between the 3 generations of particles — “flavor physics”

p.13

Weak interactions

Only the W interactions change the type of quarks

Interaction strength: Cabibbo-Kobayashi-Maskawa (CKM)Interaction strength: matrix, Vij, 3 3 unitary matrix

Flavor changing charged currents at tree levele.g.: K !

No flavor changing neutral currents (FCNC) at tree levele.g.: No K0 –K0 mixing at tree level

FCNC only at loop level in SM; suppressed by (m2i m

2j)=m

2W

e.g.: K0 –K0 mixing used to predict mc before its discovery

FCNCs are generally small in the SM, probe differences between 3 generations

p.14

Quark mixing and the unitarity triangle

The W couples (u; c; t) and (d; s; b) with strength: ( 0:23)

VCKM =

0B@Vud Vus Vub

Vcd Vcs Vcb

Vtd Vts Vtb

1CA

| z CKM matrix

0B@

1 122 A3( i)

1 122 A2

A3(1 i) A2 1

1CA

One complex phase in VCKM: only source of CP violation in quark sector9 complex couplings depend on 4 real parameters ) many testable relations

Unitarity triangle: a simple way to visualize the SM constraints and measurements

CPV in SM / Area

Vud Vub + Vcd V

cb + Vtd V

tb = 0

Sides and angles measurable in many ways

Goal: overconstrain by many measurementssensitive to different short distance physics

p.15

Interplay of electroweak and strong interactions

How to learn about high energy physics from low energy hadronic processes?

QED: at larger energy we probe shorter distances, feelQED: bigger charge (less screened)

QCD: because of gluons’ self-interaction, anti-screening

Nobel prize, 2004:

Politzer, Wilczek, Gross

p.16

Interplay of electroweak and strong interactions

How to learn about high energy physics from low energy hadronic processes?

QED: at larger energy we probe shorter distances, feelQED: bigger charge (less screened)

QCD: because of gluons’ self-interaction, anti-screening

High energy (short distance): perturbation theory is useful

Low energy (long distance): QCD becomes nonperturbative ) it is usually veryhard, if not impossible, to make precise calculations

Solutions: New symmetries, effective theories both useful in limited cases

Solutions: Lattice QCD (bite the bullet)

Incalculable nonperturbative physics often limits the sensitivity (“brown muck”)

p.16

“Seeing” virtual heavy particles

Flavor changing interactions dueto virtual heavy particles ) manydifferent “new” interactions

Depend only on a few parametersin the SM + strong suppressions

weak / NP scale 5GeV

SM predicts correlations between observables — new physics may violate some

Does the SM (i.e., W , Z, and quarks in tree and loop diagrams) explain all flavorchanging interactions? Right coefficients? Right operators?

Challange: small theoretical uncertainties, good experimental precision

New particles (even if much heavier than mW ; mt) could have observable effects[an example)]

p.17

Back of an envelope calculation of mK

In the SM: mK g4 jVcsVcdj

2

162m2c

m4W

mK f2K

(severe suppressions!)K0

K0

Tree-level exchange of a hypothetical boson:

m(X)K

m(exp)K

g23QCDM2XmK

) MX > g 2 103 TeV

Similarly, from B0B0 mixing: MX > g3 102 TeV

New TeV-scale particles can have large contributions even in loops (g 0:01)

In many NP models the constraints from kaons are the strongest, since so arethe SM suppressions — these are built into the models since the 70’s

p.18

Spectacular track record

FCNCs and CP violation are excellent probes of new physics

– -decay predicted neutrino (Pauli)

– Absence of KL ! predicted charm quark (Glashow, Iliopoulos, Maiani)

– CP violation (K) predicted 3rd generation (Kobayashi & Maskawa)

– K0 –K0 mixing (mK) predicted mc (Gaillard & Lee)

– B0 –B0 mixing (mB) predicted large mt

If there is NP at the TEV scale, it must have a very special flavor & CP structure

What does the B-factory data tell us? What can future improvements teach us?

p.19

Looking for NP with B decays

CDF

What’s special about B mesons?

Many interesting processes with clean theoretical interpretations:

– Top quark loops not too strongly suppressed

– Large CP violating effects possible, some with clean interpretation

– Some of the hadronic physics understood model independently (mb QCD)

Experimentally feasible to study:

– (4S) resonance is clean source of B mesons

– Long B meson lifetime

– Timescale of oscillation and decay comparable: m= ' 0:77 (and )

p.20

“Seeing” B decays at LEP Nch=17 EV1=.935 EV2=.681 EV3=.123 ThT=1.93 Detb= E0FBFF

ALEPH.40Gev EC1.6Gev HC

Z0<4 YX

0|−10cm 10cm|X’

0|−

8cm

8cm

|Y

’

Z0<4 YX

0|−1cm 1cm|X’

0|−

0.1

cm

0

.1cm

|Y

’

K

πD**π

D*π

µ+

+

−+−

Do−B+IP

3 σ ellipses

run = 15419 event = 5991

B −> D+ ** o__

µ ν+µ

K

πD**π

D*π

µ+

+

−+−

Do−B+IP

3 σ ellipses

run = 15419 event = 5991

B −> D+ ** o__

µ ν+µ

“Seeing” B decays at the Tevatron

Tremendous progress in the last decade

For 35 years, untill 1999, only unambiguous measurement of CP violation was KAccommodated by O(1) KM phase, but precision test with 0K is not (yet) possible

Uncertainties reduced by an order of magnitude:

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]

(Vud Vub + Vcd V

cb + Vtd V

tb = 0)

γ

α

α

dm∆

Kε

Kεsm∆ & dm∆

ubV

βsin 2

(excl. at CL > 0.95)

< 0βsol. w/ cos 2

α

βγ

ρ

­0.4 ­0.2 0.0 0.2 0.4 0.6 0.8 1.0η

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

exclu

ded a

rea h

as C

L >

0.9

5

ICHEP 10

CKMf i t t e r

How can one get theoretically clean information?

Improvements in bounds on new physics even more significant

p.21

CPV in interference between decay and mixing

Can get theoretically clean information in somecases whenB0 andB0 decay to same final state

Mixing: jBH;Li = pjB0iqjB0i — in SM: q=p e2i

0B

0B

CPf

q/p

A

A

Time-dependent CP asymmetry:

afCP =[B

0(t)! fCP ] [B

0(t)! fCP ]

[B0(t)! fCP ] + [B

0(t)! fCP ]

If amplitudes with one weak phase dominate, hadronic physics drops out:

afCP = (1) sin(phase difference between decay paths) sin(mt)arg[(q=p)(A=A)]

Measure a phase in the Lagrangian with very small theoretical uncertainty

[Solves the problem of theory uncertainties — need to do challenging measurements]

p.22

Quantum entanglement — using EPR

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 determines flavor of other B at t = t1

p.23

Asymmetric-energy ee+ colliders

... to measure time dependence of decay after the collision

CP violation in B ! J= KS by the naked eye

CP violation is O(1): sin 2 = 0:673 0:023

d

d

d

s

b

W c

cψ

K

B

S

afCP =[B

0(t)! K] [B

0(t)! K]

[B0(t)! K] + [B

0(t)! K]

= sin 2 sin(mt)

CP violation in K decays is small because of small CKM elements, not becauseCP violation is generically small — it is large in some B decays

p.24

Another key measurement: “sin 2” in loops

B ! KS unsuppressed SM tree diagram

d

d

d

s

b

W c

cψ

K

B

S

B ! KS, etc., SM loops or NP loops?

s

sd

d

W

g

bu, c, t

B

s

K

d

S

φ

b

bR

R

~ sR~

s

s

s

s

R,L

R,L

R

R

~(δ23)RR

d_

No significant deviations, howevertheory uncertainty experimental error

sin(2βeff

) ≡ sin(2φe1ff)

HF

AG

FP

CP

2010

HF

AG

FP

CP

2010

HF

AG

FP

CP

2010

HF

AG

FP

CP

2010

HF

AG

FP

CP

2010

HF

AG

FP

CP

2010

HF

AG

FP

CP

2010

HF

AG

FP

CP

2010

HF

AG

FP

CP

2010

HF

AG

FP

CP

2010

HF

AG

FP

CP

2010

HF

AG

FP

CP

2010

HF

AG

FP

CP

2010

HF

AG

FP

CP

2010

b→ccs

φ K

0

η′ K

0

KS K

S K

S

π0 K

0

ρ0 K

S

ω K

S

f 0 K

S

f 2 K

S

f X K

S

π0 π

0 K

S

φ π

0 K

S

π+ π

- KS N

R

K+ K

- K0

-2 -1 0 1 2

World Average 0.67 ± 0.02BaBar 0.26 ± 0.26 ± 0.03Belle 0.90

+-00..0199

Average 0.56 +-00..1168

BaBar 0.57 ± 0.08 ± 0.02Belle 0.64 ± 0.10 ± 0.04Average 0.59 ± 0.07BaBar 0.90

+-00..1280

+-00..0034

Belle 0.30 ± 0.32 ± 0.08Average 0.74 ± 0.17BaBar 0.55 ± 0.20 ± 0.03Belle 0.67 ± 0.31 ± 0.08Average 0.57 ± 0.17BaBar 0.35

+-00

.

.2361 ± 0.06 ± 0.03

Belle 0.64 +-00

.

.1295 ± 0.09 ± 0.10

Average 0.54 +-00..1281

BaBar 0.55 +-00

.

.2269 ± 0.02

Belle 0.11 ± 0.46 ± 0.07Average 0.45 ± 0.24BaBar 0.60

+-00..1168

Belle 0.63 +-00..1169

Average 0.62 +-00..1113

BaBar 0.48 ± 0.52 ± 0.06 ± 0.10Average 0.48 ± 0.53BaBar 0.20 ± 0.52 ± 0.07 ± 0.07Average 0.20 ± 0.53BaBar -0.72 ± 0.71 ± 0.08Average -0.72 ± 0.71BaBar 0.97

+-00..0532

Average 0.97 +-00..0532

BaBar 0.01 ± 0.31 ± 0.05 ± 0.09Average 0.01 ± 0.33BaBar 0.86 ± 0.08 ± 0.03Belle 0.68 ± 0.15 ± 0.03

+-00

.

.21

13

Average 0.82 ± 0.07

H F A GH F A GFPCP 2010

PRELIMINARY

Much larger LHCb and super-(KEK-)B data sets will be sensitive to smaller effects

p.25

And a lot more: the B factory decade

By now >109 B decays recorded / analyzed

Q: How many CP violating quantities are measured with > 3 significance?

A: 13; B: 18; C: 23; D: 28 (with different sensitivity to new physics)

p.26

And a lot more: the B factory decade

By now >109 B decays recorded / analyzed

Q: How many CP violating quantities are measured with > 3 significance?

A: 13; B: 18; C: 23 (with different sensitivity to new physics)

K, 0K,

S K, S0K, Sf0K, SK, SK+KK0, S3KS, S 0, SD+D, SD+D, SD+D, S+

A0K+, AK+, Af2K+, AK+, AK0, A+, A, C, aD, ADCP+

K

Just because a measurement determines a CP violating quantity, it no longerautomatically implies that it is interesting

(E.g., if SK were still consistent with 0, it would be a conclusive discovery of new physics!)

It doesn’t matter if a measurement is CP violating or conserving — only the exper-imental and theoretical precision for interpretation for short distance physics is

p.26

Can we see new physics in loops?

Neutral meson mixing:

OR) AND?

Simple parameterization for each neutral meson: M12 =MSM12 (1 + he2i)

Loop-dominated decays:

W

γbR sLt

OR) AND?H−

γbR sLt

Many operators for b! s transitions — no simple parameterization of NP

Vts; Vtd only measurable in loops; likely also subleading couplings of new particles

Isolating modest NP contributions requires many measurementsCompare NP-independent (tree) with NP-dependent (loop) processes

p.27

Overconstraining the standard model

(CP conserving) (CP violating)

(tree-level) (loop-dominated)

Consistent determinations from subsets of measurements ) bound extra terms

p.28

The one-page highlight of BaBar & Belle

Constrain (NP / SM) in B0 –B0 mixing from <10 to <1, and approaching 1

M12 =MSM12 (rd e

2id) =MSM12 (1 + hd e

2id)

-150

-100

-50

0

50

100

150

0 1 2 3 4 5 6 7 80

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

New Physics in B0B0 mixing

rd 2

2θd

(

deg)

C K Mf i t t e r

ICHEP 2004

Qualitative change before vs. after 2004 — to me, the real justification for the 2008 Nobel Prize

O(20%) NP contributions to most loop processes still possible; is avor weak?

p.29

Can even probe DM models with B decays

Recent observations of cosmic ray excesses lead to flurry DM model building

E.g., “axion portal”: light (< 1GeV) scalar particle coupling as (m =fa) 5 a

1 TeV

2 TeV

3 TeV

5 TeV

10 TeV20 TeV

30 TeV

1 TeV

2 TeV3 TeV

5 TeV10 TeV20 TeV

30 TeV

50 TeV

0 1 2 3 4 5 60

200

400

600

800

1000

1200

1400

tan Β

mH

HGeV

L

Bound on fa

[Freytsis, ZL, Thaler, arXiv:0911.5355]

In most of parameter space best bound is from B ! K`+`, LHCb can improve it

p.30

Summary of things we learned

The CKM phase is the dominant source of CP violation (in meson decays)

CP violation is O(1), just screened by small flavor violation in K and D decays

New physics in most FCNC processes may still be >10% of the SM contributions

Measurements probe scales 1TeV; sensitivity limited by statistics, not theory

Few hints of discrepancies — need more data to resolve them

Great synergy between theoretical and experimental developments to learn bothabout electroweak and strong interactions

p.31

Where do we go from here?

Flavor physics in the LHC era

Reasons to pursue flavor physics

Hopefully the LHC will discover new particlesMany subleading couplings not measurable directly (Vtd & Vts fromB and not t decay)

In many models: largemt) non-universal coupling to EWSB

Motivated models: NP , 3rd gen. 6= NP , 1st & 2nd gen.t

t

H H

Is the physics of 3rd–1st, 3rd–2nd, and 2nd–1st generation transitions the same?

SUSY: soft SUSY breaking terms ) mechanism of SUSY breaking, mediation

If no NP is seen in flavor sector, similar constraints as LEP tests of gauge sector

If non-SM flavor physics is seen, try to distinguish between classes of models:

– One / many sources of CPV?– In charged / neutral currents?– Modify SM operators / new operators?

– Couples to up / down sector?– To 3rd / all generations?– Quarks / leptons / other sectors?

p.32

Some LHCb highlights

CP violation in Bs mixing not yet established, large NP contributions still allowed

sh0 0.5 1 1.5 2 2.5 3 3.5

sσ

0

20

40

60

80

100

120

140

160

180

sh0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

sσ

0

20

40

60

80

100

120

140

160

180

After measurement of ms 1yr nominal LHCb, (S )=0:03

Theory uncertainty1 allowed region2 allowed region

[ZL, Papucci, Perez, hep-ph/0604112]

LHCb will probe new physics in the Bs sector at a level comparable to Bd

Difference of CP asymmetries, SBs! SBs!

Bs ! + (/ tan6 ), search for Bd ! +, other rare / forbidden decays

1045 events in B ! K()`+`, Bs ! , . . . — test Dirac structure, BSM op’s

from B ! DK and Bs ! DsK (for probably super-B wins)

p.33

LHC as a top factory: FCNC top decays?

Flavor violation in top decays not well exploredSM 1013, current bound 102

LHC: 1 tt pair / sec ) sensitivity < 105

Observable top FCNC possible in extensions ofthe SM and still allowed by B-factory constraints

[Fox, ZL, Papucci, Perez, Schwartz, arXiv:0704.1482]

l

ν

tW

Z

u, c

t

l

l

b

Indirect constraints: tL $ bL — tight bounds fromB decays

– Strong bounds on operators with left-handed fields

– Right-handed operators could give rise to LHC signals

If top FCNC is seen, LHC & B factories will both probe the NP responsible for it

p.34

CDF: tt forward-backward asymmetry

CDF: Att(mtt > 450GeV) = 0:475 0:114 [arXiv:1101.0034]

3:4 from SM Consistent with SM

QCD NLO tt

ttA

2GeV/c 450 ttM

0.0

2.0

4.0

2.0−

-1fb 5.3 data CDFlevel-parton tt

]2 [GeV/ctt

Unfolded M

0 200 400 600 800 1000 1200 1400]

2 [

fb/G

eV

/ctt

/dM

σd

-110

1

10

SM Expectation

Data

Lots of recent theory papers, from ad-hoc flavor structure to MFV [Alex, Jure, etc.]

Severe constraints: flavor physics, top cross section, dijet cross sections

No model fits all of the data really well — LHC may clarify the picture soon

p.35

Supersymmetry and flavor at the LHC

After the LHC discovers new particles (and the champagne is gone):

What are their properties: mass, decay modes, spin, production cross section?

My prejudice: I hope the LHC will discover something unexpectedOf the known scenarios I view supersymmetry as the most interesting

– How is supersymmetry broken?– How is SUSY breaking mediated to MSSM?– Predict soft SUSY breaking terms?

Details of interactions of new particles with quarks and leptons will be importantto understand underlying physics

In SUSY, CP violation possible in squark & slepton couplings, flavor diagonalprocesses (e; n EDM’s), neutral currents; may enhance FCNCs (b! s , ! e )

p.36

K0 –K0 mixing in supersymmetry

(mK)

SUSY

(mK)exp 104

1TeV

~m

2 ~m2

12

~m2

2Re(Kd

L)12(KdR)12

KdL(R): mixing in gluino couplings to left-(right-)handed down quarks and squarks

Classes of models to suppress each factors

(i) Heavy squarks: ~m 1TeV (e.g., split SUSY)

(ii) Universality: m2~Q; ~D

~m2 (e.g., gauge mediation)

(iii) Alignment: j(KdL;R)12j 1 (e.g., horizontal symmetries)

D0 –D0 mixing discovery (BaBar & Belle, 2007) ruled out (iii) as sole explanation

Has driven SUSY model building — all models incorporate some of the above

[Most of the benchmark points studied by ATLAS & CMS set flavor change to zero “by hand”]

p.37

Flavor effects at the TeV scale

Does flavor matter at ATLAS & CMS? Can we probe Sflavor directly at high pT?

Some flavor aspects of LHC: pp @ Ecm 10TeV

– p = g + u; d; s; c; b; u; d; s; c;b — has flavor

– Hard to bound flavor properties of new particles (e.g., Z 0 ! bb vs. Z 0 ! bs?)

– Little particle ID: b (displaced vertex), t (which pT range?), + other “jets”

What flavor data the LHC can give us:

– Spectrum (degeneracies), which mass splittings can be probed?

– Information on some (dominant?) decay widths

– Production cross sections

As in QCD, spectroscopy can give dynamical information

p.38

Detection of SUSY particles

At each vertex two supersymmetric particles

Lightest SUSY particle (LSP) undetected

Reconstruct masses via kinematic endpoints

Most experimental studies use referencepoints which set flavor (i.e., generation) off-diagonal rates to zero (and ~m2

1 = ~m22 6= ~m2

3)

Some off-diagonal rates can still be 10– 20%or more, consistent with all low energy data

Flavor can complicate determination of sparticle masses from cascade decays... can modify the discovery potential of some particles

p.39

A recent trend: flavorful SUSY models

Emerging models with interesting flavor structure, consistent with all data

Many studies over the last year (and in progress), mostly based on SUSY

“Dilute” (but not completely eliminate) SUSY flavor violation with

– mixed gauge / gravity mediated SUSY breaking [Feng et al.; Nomura, Papucci, Stolarski; Hiller et al.]

– heavy Dirac gaugino masses (going beyond the MSSM) [Kribs, Poppitz, Weiner]

Emerging themes:

– Viable model space often thought; sizable flavor non-universalities possible

– Easier to tag lepton than quark flavor ) slepton flavor violation probably more– accessible than squark flavor violation

Slepton spectrum and branching ratios may contain useful info on flavor physics[Possible synergies with ! e and other lepton flavor violation experiments]

p.40

Possible pictures in a few years

Combination of LHC and flavor physics measurements can be very powerful todiscriminate between models

Present constraints on masses & couplings Future constraints

EXCLUDED

MFV

00

1

1Kij

mj - mi

mj + mi

LHCb

ATLAS/CMS

00

1

1Kij

mj - mi

mj + mi

p.41

Final comments

B physics anomalies on the watch list

ASL — CP violation inBd;s mixing: 3

dsla

s sla

68%95%

99% C.L.

-1DØ, 6.1 fb

b slDØ A

Standard ModelB Factory W.A.

Xµ sD→ sDØ BPreliminaryCombination

-0.04 -0.03 -0.02 -0.01 0 0.01

-0.03

-0.02

-0.01

0

0.01

s — analog of , mea-sured in Bs ! : 2

B(B ! ) — above theSM prediction: 2:5

βsin 2

0.5 0.6 0.7 0.8 0.9 1.0

)ντ

→B

R(B

0.00

0.05

0.10

0.15

0.20

0.25

0.30-3

10×

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.01-CL

ICHEP 10

CKMf i t t e r

B ! K CP asymmetries: theoretically less clean, but very puzzling (many )

Improved experimental sensitivity may show unambiguous signs of new physicsin many other measurements as well

p.42

Back to dark matter, dark energy

We hope to understand at the LHC what dark matter isPromising candidate: lightest new stable particle(In most SUSY models, superpartner of a gauge boson)

Wanted to understand matter – antimatter asymmetryThe LHC may help (new particles, new CP violation)

Dark energy: accelerating expansion discovered (1998)cc 1029 g=cm3 = 1047GeV4 = 10120 (Planck units)

The LHC won’t directly address the cosmological constantproblem, but it may tell us if we (mis)understand fine-tuning

Is it just a coincidence that cc (1TeV2=MPl)4 ?

0.0 0.5 1.00.0

0.5

1.0

1.5

FlatBAO

CMB

SNe

ΩΛ

Supernova Cosmology ProjectKowalski, et al., Ap.J. (2008)

Ωm

Union 08SN Ia

compilation

p.43

Back to dark matter, dark energy

We hope to understand at the LHC what dark matter isPromising candidate: lightest new stable particle(In most SUSY models, superpartner of a gauge boson)

Wanted to understand matter – antimatter asymmetryThe LHC may help (new particles, new CP violation)

Dark energy: accelerating expansion discovered (1998)cc 1029 g=cm3 = 1047GeV4 = 10120 (Planck units)

Others also know that dark energymakes things grow...

p.43

Conclusions

Consistency of precision flavor measurements with SM is a problem for NP @ TeVHowever, new physics in most FCNC processes may still be > 20% of the SM

Few hints of discrepancies — existing data could have shown new physics, com-pelling reasons to continue (theoretical uncertainties won’t be limiting)

Low energy tests will improve a lot in next decade, by 10–1000 in some channelsExploring influence of NP requires LHCb, super-B-factory, K, lepton flavor viol.

If new particles are discovered, their flavor properties can teach us about TeV

... masses (degeneracies), decay rates (flavor decomposition), cross sections

... many possible synergies between low energy & TeV-scale information on NP

We have a good chance to learn an incredible amount in the next decade

... interplay of experiment and theory will continue, and should be a lot of fun

p.44

We know there is exciting physics out there

Just need to look at a bit shorter distances?

A diamond field in Namibia

Additionall Topics

Masses of elementary particles

Representations of SU(3)c SU(2)L U(1)Y

quarks:QL(3; 2)1=6; uR(3; 1)2=3; dR(3; 1)1=3

3 copies

leptons:LL(1; 2)1=2; `R(1; 1)1

3 copies [R(1; 1)0 ?]

Problem: SM gauge symmetries forbid m fermion mass terms (also W, Z0)

Loophole: the vacuum can also be charged

“Higgs condensate” has SU(2) U(1) charge

(also gives mass to W; Z0, but not to )

Q(3; 2)1=6 Y uij u(3; 1)2=3

(1; 2)1=2

Mass is an interaction with something unknown

Simplest model: Higgs = SU(2)L doublet scalar field

Simplest model: after it acquires a vev ) one physical Higgs boson

p.i

Lepton flavor violation (in decays)

! e vs. ! (few 109)

Very large model dependenceB( ! )=B(! e ) 1032

In many models best bet is ! e , but there are lots of exceptions

! `1 `2 `

+3 (few 1010) vs. !

Consider operators: RFL, (L L)(L L)

Suppression by em opposite in two cases ) modeldependent which process gives the best sensitivity

Super B sensitivity with 75 ab1

! e and (g 2) operators are very similar: m

2F

e ;

m

2F

If coefficients comparable, ! e gives much stronger boundIf (g 2) is due to NP, large hierarchy of coefficients () model building lessons)

p.ii

Recent trends: (i) minimal flavor violation

MFV: a class of models which solves the NP flavor puzzle (GMSB, mSUGRA, ...)[Chivukula & Georgi; Hall & Randall; D’Ambrosio, Giudice, Isidori, Strumia; Buras et al.]

Assume SM Yukawas are only source of flavor and CP violation (cannot demandall higher dimension operators to be flavor invariant and contain only SM fields)

Spectra: yu;d;s;c 1, so first two generation squarks are quasi-degenerate

Mixing: CKM) new particles decay to 3rd or non-3rd generation quarks, not both

CKM and GIM (mq) suppressions similar to SM; allows EFT-like analyses

Imposing MFV, best constraints from:B ! Xs ; B ! ; Bs ! +; mBs; h

2; g 2, precision electroweak

Even with MFV and TeV-scale NP, expect % level deviations from SM in B;D;K

In some scenarios high-pT LHC data may rule out MFV or make it more plausible

p.iii

Hadron colliders — no quantum correlation

B0s with sufficient boost to study CPV at Tevatron & LHC (+ Belle data on rates)

gg; qq ! bb: measure flavor of a b hadron, and flavor of B0s as a function of time

Need excellent time resolution, and fully reconstructed B0s to know its boost

p.iv

B0–B0 mixing: matter – antimatter oscillation

Quantum mechanical two-level system; flavor eigenstates: jB0i= jbdi; jB0i= jbdi

Evolution: i ddt

jB0(t)i

jB0(t)i

=

M

i

2

jB0(t)i

jB0(t)i

Evolution: M; : 2 2 Hermitian matrices

b

d

d

b

t

t

W W

b

d

d

b

W

W

t t

Mass eigenstates: jBH;Li = pjB0i qjB0i

Mass eigenstates: jBH;L(t)i = e(iMH;L+H;L=2)t jBH;Li

The SM predicts:q

p=V tbVtdVtbV td

= e2i +O(103)

New physics can modify mixing amplitude; e.g., SUSY )?

CP is violated if: mass eigenstates 6= CP eigenstates (jq=pj 6= 1 , hBHjBLi 6= 0)

We know, independent of the SM, that this form of CP violation is tiny

p.v

The “last” meson mixing: D0

Complementary to K;B: CPV, FCNC both GIM & CKM suppressed ) tiny in SM

– 2007: significance of mixing >5 [HFAG combination]

– Only meson mixing generated by down-type quarks(SUSY: up-type squarks)

– SM suppression: mD; D < 102 , since doubly-Cabibbo-suppressed and vanish in flavor SU(3) limit

– CPV (mixing or direct) > 103 would be sign of NP

– To do: Precise values of m and ?To do: Is CPV absent in mixing and decays?

x (%)

−1 −0.5 0 0.5 1 1.5 2

y (

%)

−1

−0.5

0

0.5

1

1.5

2

CPV allowed

σ 1

σ 2

σ 3

σ 4

σ 5

HFAG-charm

CHARM 2010

(x = m=, y = =2)

p.vi

The “last” meson mixing: D0

Complementary to K;B: CPV, FCNC both GIM & CKM suppressed ) tiny in SM

– 2007: significance of mixing >5 [HFAG combination]

– Only meson mixing generated by down-type quarks(SUSY: up-type squarks)

– SM suppression: mD; D < 102 , since doubly-Cabibbo-suppressed and vanish in flavor SU(3) limit

– CPV (mixing or direct) > 103 would be sign of NP

– To do: Precise values of m and ?To do: Is CPV absent in mixing and decays?

|q/p|

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

Arg

(q/p

) [d

eg

.]

−80

−60

−40

−20

0

20

40

60

80 σ 1

σ 2

σ 3

σ 4

σ 5

HFAG-charm

CHARM 2010

Not yet known if jq=pj ' 1

Particularly interesting for SUSY: mD and mK ) if first two squark doubletsare within LHC reach, they must be quasi-degenerate (alignment alone not viable)

p.vi

Flavor parameters in the SM

Nonzero Yukawa couplings break flavor symmetries — masses and mixings aredetermined by the interactions of fermions with the Higgs background

Quark sector: U(3)Q U(3)u U(3)d ! U(1) quark (baryon) number

[36 couplings] [26 broken symmetries] = 10 parameters with physical meaning

= [6 masses] +

parameters in VCKMz | [3 angles] + [1 phase]| z

Single source of CP violation in the quark sector in the SM

Lepton sector (Majorana ’s): LY = Yije LILi e

IRj

Y ij

MLILiL

ILj (Y ij

= Y ji )

Lepton sector U(3)L U(3)e completely broken

[30 couplings] [18 broken symmetries] = 12 parameters with physical meaning

= [6 masses] + [3 angles] + [3CPV phases]| z One CPV phase measurable in oscillations, others in 0 decay

p.vii

Parameters of the MSSM

Superpotential: [Haber, hep-ph/9709450]

W =P

i;j

Y uijHuQLi

ULj + Y dijHdQLi

DLj + Y `ijHdLLi ELj

+ HuHd

Soft SUSY breaking terms: (S = ~QL;~DL;

~UL; ~LL;~EL)

Lsoft =AuijHu

~QLi~ULj + A

dijHd

~QLi~DLj + A

`ijHd

~LLi~ELj + BHuHd

Xscalars

(m2S)ij Si

Sj 1

2

M1

~B ~B +M2~W ~W +M3~g~g

3 Y f Yukawa and 3 Af matrices — 6(9 real + 9 imaginary) parameters5m2

S hermitian sfermion mass-squared matrices — 5(6 real + 3 imag.) param’s

Gauge and Higgs sectors: g1;2;3; QCD;M1;2;3;m2hu;d

; ; B — 11 real + 5 imag.

Parameters: (95 + 74) (15 + 30) from U(3)5 U(1)PQ U(1)R ! U(1)B U(1)L

44 CPV phases: CKM + 3 in M1;M2; (set B;M3 real) + 40 in mixing matrices44 CPV phases: of fermion-sfermion-gaugino couplings (+80 real param’s)

p.viii

A super(-KEK)-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, S KS SKS from CP asymmetries in tree-level decays vs. from S KS and md=ms

Search for charged lepton flavor violation, ! , ! 3, 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

Rare decay searches and refinements: b! s, B ! , etc.

Complementary to LHCb

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

p.ix

A real B ! KS event...