Hints for new physics from radiative / electroweak B decays

Zoltan Ligeti

Hints for new physics in flavor decays KEK, 20-21 March 2009

• Introduction • b→ sγ: Rate, asymmetries, inclusive & exclusive • b→ s`+`−: Optimal observables to constrain short distance physics

Small and large q2 regions; sensitivity to shape function, connections to |Vub|

• b→ sνν̄: The theoretically cleanest of all • Conclusions

Preliminaries / Disclaimers

• In a previous millenium (i.e., mid-1990’s), I did not care too much about what had been measured (my apologies to CLEO!), only what might be measured one day

Z. Ligeti — p. 1

Preliminaries / Disclaimers

• In a previous millenium (i.e., mid-1990’s), I did not care too much about what had been measured (my apologies to CLEO!), only what might be measured one day

It was fun, sometimes I miss those days... sounding like a really old person :-)

Z. Ligeti — p. 1

Preliminaries / Disclaimers

• In a previous millenium (i.e., mid-1990’s), I did not care too much about what had been measured (my apologies to CLEO!), only what might be measured one day

It was fun, sometimes I miss those days... sounding like a really old person :-)

• So I will not talk specifically about any of the ∼2σ hints available today... I think it’s more interesting to explore what’s possible with ∼100 times more data

(These measurements are of course important; chance of >3σ before upgrade?)

Z. Ligeti — p. 1

Preliminaries / Disclaimers

• In a previous millenium (i.e., mid-1990’s), I did not care too much about what had been measured (my apologies to CLEO!), only what might be measured one day

It was fun, sometimes I miss those days... sounding like a really old person :-)

• So I will not talk specifically about any of the ∼2σ hints available today... I think it’s more interesting to explore what’s possible with ∼100 times more data

(These measurements are of course important; chance of >3σ before upgrade?)

• Existing Super-B studies tend to concentrate on observables in exclusive modes, so I’ll focus on inclusive (K∗`+`− also possible at LHCb)

Z. Ligeti — p. 1

Preliminaries / Disclaimers

• In a previous millenium (i.e., mid-1990’s), I did not care too much about what had been measured (my apologies to CLEO!), only what might be measured one day

It was fun, sometimes I miss those days... sounding like a really old person :-)

• So I will not talk specifically about any of the ∼2σ hints available today... I think it’s more interesting to explore what’s possible with ∼100 times more data

(These measurements are of course important; chance of >3σ before upgrade?)

• Existing Super-B studies tend to concentrate on observables in exclusive modes, so I’ll focus on inclusive (K∗`+`− also possible at LHCb)

• In my opinion, building a Super-B-factory is clearly justified 2–3σ effects may be temporary, so let’s concentrate on finding the best combina- tions of theoretical cleanliness and experimental feasibility

Z. Ligeti — p. 1

Main reason (for me) to continue

3 φ

3 φ

2 φ

2 φ

dm∆ Kε

Kε

sm∆ & dm∆

SLub V

ν τub V

1 φsin 2

(excl. at CL > 0.95)

< 0 1

φsol. w/ cos 2

excluded at C L > 0.95

2 φ

1 φ

3 φ

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

Moriond 09

CKM f i t t e r

dh 0.0 0.2 0.4 0.6 0.8 1.0

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

1.0 1-CL

Moriond 09

CKM f i t t e r

ντ →w/o B

• Very impressive accomplishments • Level of agreement between various

measurements often misinterpreted

Parameterize: M12 = MSM12 (1 + hd e2iσd)

Most loop-mediated transitions may have 10–20% NP contributions w/o fine tuning

Z. Ligeti — p. 2

The rare B decay landscape

• Important probes of new physics (a crude guide, ` = e or µ) Decay ∼SM rate present status expected

B → Xsγ 3.2× 10−4 (3.52± 0.25)× 10−4 4% B → τν 1× 10−4 (1.73± 0.35)× 10−4 5% B → Xsνν̄ 3× 10−5 < 6.4× 10−4 only Kνν̄ ? B → Xs`+`− 6× 10−6 (4.5± 1.0)× 10−6 6% Bs → τ+τ− 1× 10−6 < few % Υ(5S) run ? B → Xs τ+τ− 5× 10−7 < few % ?

B → µν 4× 10−7 < 1.3× 10−6 6% B → τ+τ− 5× 10−8 < 4.1× 10−3 O(10−4) Bs → µ+µ− 3× 10−9 < 5× 10−8 LHCb B → µ+µ− 1× 10−10 < 1.5× 10−8 LHCb

• Many interesting modes will first be seen at super-B (or LHCb) Maintain ability for inclusive studies as much as possible (smaller theory errors)

• Some of the theoretically cleanest modes (ν, τ , inclusive) only possible at e+e−

Z. Ligeti — p. 3

B → Xsγ

Inclusive B → Xsγ calculations

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

• NNLO practically completed [Misiak et al., hep-ph/0609232] 4-loop running, 3-loop matching and matrix elements

Scale dependencies significantly reduced ⇒

• B(B → Xsγ) ∣∣ Eγ>1.6GeV

= (3.15± 0.23)× 10−4

measurement: (3.52± 0.25)× 10−4

• O(104) diagrams, e.g.: b s

c

c

γ

�

Z. Ligeti — p. 4

The B → Xsγ photon spectrum

• World average: B(B → Xsγ) = (3.52± 0.25)10−4 Could have easily shown deviations from SM

• Exp. cut: Eγ >∼ 1.9 GeV ⇒ mB − 2Ecutγ ∼ 1.5 GeV Three cases: 1) Λ ∼ mB − 2Eγ � mB Three cases: 2) Λ� mB − 2Eγ � mB Three cases: 3) Λ� mB − 2Eγ ∼ mB Neither 1) nor 2) is appropriate

• Can combine 1–2 w/o expanding Λ/(mB − 2Eγ) [ZL, Stewart, Tackmann, 0807.1926]

9 models with the same 0th, 1st, 2nd moments =⇒ Including all NNLL corrections, smaller shape func- tion uncertainty for Eγ

Photon polarization in B → Xsγ

• Is B → Xsγ due to O7 ∼ s̄ σµνFµν(mbPR+msPL)b or s̄ σµνFµν(mbPL+msPR)b? SM: In ms → 0 limit, γ must be left-handed to conserve Jz O7 ∼ s̄ (mbFLµν +msFRµν) b , therefore b→ sLγL dominates

� ����������

Inclusive B → Xsγ γ sb

Assumption: 2-body decay Does not apply for b→ sγg

Exclusive B → K∗γ γ KB *

... quark model (sL implies JK ∗

z = −1) ... higher K∗ Fock states

• Had been expected to give SK∗γ = −2 (ms/mb) sin 2φ1 [Atwood, Gronau, Soni] Γ[B0(t)→ K∗γ]− Γ[B0(t)→ K∗γ] Γ[B0(t)→ K∗γ] + Γ[B0(t)→ K∗γ]

= SK∗γ sin(∆mt)− CK∗γ cos(∆mt)

• Data: SK∗γ = −0.16±0.22 — both the measurement and the theory can progress Z. Ligeti — p. 6

Right-handed photons in the SM

• Dominant source of “wrong-helicity” photons in the SM is O2 Equal b→ sγL, sγR rates at O(αs); calculated to O(α2sβ0)

Inclusively only rates are calculable: Γ(brem)22 /Γ0 ' 0.025

Suggests: A(b→ sγR)/A(b→ sγL) ∼ √

0.025/2 = 0.11

[Grinstein, Grossman, ZL, Pirjol]

b s

c O2

gγ

• B → K∗γ: At leading order in ΛQCD/mb, wrong helicity amplitude vanishes Subleading order: no longer vanishes [Grinstein, Grossman, ZL, Pirjol]

Order of magnitude: A(B 0 → K0∗γR)

A(B0 → K0∗γL) = O

„ C2

3C7

ΛQCD

mb

« ∼ 0.1

Some additional suppression expected, but I don’t find

Other observables

• Direct CP asymmetry: AB→Xsγ = −0.012± 0.028 AB→Xd+sγ = −0.011± 0.012 AB→K∗γ = −0.010± 0.028

Theoretical predictions < 0.01, except AB→ργ which is larger

• Isospin asymmetry: it seems to me that theoretical uncertainties would make it hard to argue for new physics

• If these observables don’t show NP, I doubt higher K states, etc., could

Z. Ligeti — p. 8

B → Xs`+`−

Inclusive b→ s`+`− calculations • Complementary to B → Xsγ • Subtleties in power counting (as in K → πe+e−) C9(mb) ∼ C9(mW) + (. . .)

C2(mW)

αs(mW)

 1− » αs(mb)

αs(mW)

–(···)ff Scale & scheme dependence cancellation tricky

• NNLL: 2-loop matching, 2- and 3-loop running NNLL: 2-loop matrix elements

B(B→Xs`+`−) ∣∣ 1

The q2 spectrum in B → Xs`+`−

• Rate depends (mostly) on O7 =mb s̄σµνeFµνPRb,

O9 = e2(s̄γµPLb)(¯̀γµ`),

O10 = e2(s̄γµPLb)(¯̀γµγ5`)

Theory most precise for 1 GeV2 < q2 < 6 GeV2−→ • NNLL b→ s`+`− perturbative calculations

Introduce Ceff7,9 — complex with usual definition 0 5 10 15 20

0

1

2

3

4

[Ghinculov, Hurth, Isidori, Yao]

• Nonpertu