Observables and anomalies in B → K(∗)ℓ+ℓ− decays
Sam Cunliffe on behalf of the LHCb collaboration.
[stc09@ic.ac.uk]
Frontiers in Fundamental Physics, Aix Marseille Universit´ e 18th July 2014
Observables and anomalies in B K ( ) + decays Sam Cunliffe on - - PowerPoint PPT Presentation
Observables and anomalies in B K ( ) + decays Sam Cunliffe on behalf of the LHCb collaboration. [stc09@ic.ac.uk] Frontiers in Fundamental Physics, Aix Marseille Universit e 18th July 2014 Why study rare decays? The LHCb
[stc09@ic.ac.uk]
Frontiers in Fundamental Physics, Aix Marseille Universit´ e 18th July 2014
S.Cunliffe (Imperial) FFP14 2/21
◮ ‘Rare’ Flavour-Changing Neutral Current processes
◮ Forbidden at tree level =
⇒ proceed via loops (in SM) s b µ− µ+ W − Z0, γ
◮ Searching for new particles via their indirect influence on rare processes
◮ Access to much higher mass scales (particles are virtual) ◮ Able to be model independent ◮ Search for broad classes of new particles at once
◮ For other flavour observables (and another perspective on b→ sℓℓ), see talk
S.Cunliffe (Imperial) FFP14 Why study rare decays? 3/21
◮ If you want to learn about space... ◮ If you want to find new particles... STS-I Launch - NASA/CC [Source] Very Large Array - Image courtesy of NRAO/AUI [Source]
S.Cunliffe (Imperial) FFP14 Why study rare decays? 4/21
◮ If you want to learn about space... ◮ If you want to find new particles... CMS Monojet candidate - [Source]
S.Cunliffe (Imperial) FFP14 Why study rare decays? 4/21
◮ If you want to learn about space... ◮ If you want to find new particles...
S.Cunliffe (Imperial) FFP14 Why study rare decays? 4/21
◮ If you want to learn about space... ◮ If you want to find new particles...
S.Cunliffe (Imperial) FFP14 Why study rare decays? 4/21
◮ If you want to learn about space... ◮ If you want to find new particles...
S.Cunliffe (Imperial) FFP14 Why study rare decays? 4/21
◮ If you want to learn about space... ◮ If you want to find new particles...
S.Cunliffe (Imperial) FFP14 Why study rare decays? 4/21
Beauty Experiment at Small Theta
◮ Physics reach in other areas than rare b→ sℓℓ
◮ e.g. talks by J. Dalseno on CPV in multibody B
decays and B. Couturier on LHCb outreach/education
◮ 2 < η < 5 ◮ Tracking:
◮ Vertexing:
◮ Kaon ID = 95%
◮ Muon ID = 98%
/4 π /2 π /4 π 3 π /4 π /2 π /4 π 3 π
[rad]
1
θ [rad]
2
θ
1θ
2θ b b
zLHCb MC = 8 TeV s
S.Cunliffe (Imperial) FFP14 The LHCb detector 5/21
Or: how to be model independent
S.Cunliffe (Imperial) FFP14 b → sℓℓ Theory 6/21
Or: how to be model independent
◮ “Effective operators” Oi ◮ “Wilson Coefficients” Ci
◮ c.f. GF from 4 point β decay model ◮ Can predict Ci’s for SM and NP scenarios
◮ Have an effective Hamiltonian =
ts
iO′ i
S.Cunliffe (Imperial) FFP14 b → sℓℓ Theory 7/21
Or: how to be model independent
◮ “Effective operators” Oi ◮ “Wilson Coefficients” Ci
◮ c.f. GF from 4 point β decay model ◮ Can predict Ci’s for SM and NP scenarios
◮ Have an effective Hamiltonian =
ts
iO′ i
S.Cunliffe (Imperial) FFP14 b → sℓℓ Theory 7/21
Or: how to be model independent
◮ “Effective operators” Oi ◮ “Wilson Coefficients” Ci
◮ c.f. GF from 4 point β decay model ◮ Can predict Ci’s for SM and NP scenarios
◮ Have an effective Hamiltonian =
ts
iO′ i
S.Cunliffe (Imperial) FFP14 b → sℓℓ Theory 7/21
Or: how to be model independent
◮ “Effective operators” Oi ◮ “Wilson Coefficients” Ci
◮ c.f. GF from 4 point β decay model ◮ Can predict Ci’s for SM and NP scenarios
◮ Have an effective Hamiltonian =
ts
iO′ i
S.Cunliffe (Imperial) FFP14 b → sℓℓ Theory 7/21
Enter form factor uncertainty
◮ Observables also contain contributions Hadronic Form Factors. ◮ Different theorists use different versions/approximations.
S.Cunliffe (Imperial) FFP14 b → sℓℓ Theory 8/21
Enter form factor uncertainty
◮ Observables also contain contributions Hadronic Form Factors. ◮ Different theorists use different versions/approximations.
S.Cunliffe (Imperial) FFP14 b → sℓℓ Theory 8/21
⊥
S6
9
AFB
|2
P ′
4
b → sγ
1
ξ
2
⊥
S6
9
AFB
|2
P ′
4
b → sγ
1
ξ
2
◮ Need to find measurable quantities that...
◮ ...are sensitive to the Wilson Coefficients ◮ ...cancel the QCD uncertainty (hadronic form factors) wherever possible
τB0 τB+ B
τB0 τB+ B
FFP14 b → sℓℓ Theory 10/21
◮ Measure asymmetry in rate
◮ B0 → K∗0(→ K±π∓)µ+µ− ◮ B± → K∗±(→ K0 Sπ±)µ+µ− ◮ B0 → K0 Sµ+µ− ◮ B± → K±µ+µ−
◮ Asymmetry v.close to zero in SM ◮ Experimental challenge:
◮ K0
S → π+π− reconstruction ◮ Normalise to
◮ 3 fb−1 2011+2012 data
]
2
c ) [MeV/
−
µ
+
µ
−
π
+
K ( m
5200 5400 5600
)
2
c Candidates / ( 10 MeV/
200 400
LHCb
−
µ
+
µ
*0
K → B
]
2
c ) [MeV/
−
µ
+
µ
+
π
S
K ( m
5200 5400 5600
)
2
c Candidates / ( 10 MeV/
20 40 60
LHCb
−
µ
+
µ
*+
K →
+
B
S.Cunliffe (Imperial) FFP14 Isospin asymmetry of B → K(∗)µ+µ− 11/21
τB0 τB+ B
τB0 τB+ B
4
2
2
5 10 15 20 I
0.5 1
LHCb
−
µ
+
µ K → B
*
4
2
2
5 10 15 20 I
0.5 1
LHCb
−
µ
+
µ K → B
◮
S.Cunliffe (Imperial) FFP14 Isospin asymmetry of B → K(∗)µ+µ− 12/21
For B0 → K∗(892)0(→ K±π∓)µ+µ− decays...
◮ P → V V ′ (pseudoscalar to vector-vector) ◮ Vector K∗(892) =
B0 K* 0 K+
π - μ - μ+
θK θℓ φ
◮ 3 angles, and q2
◮ Angular distribution −
T, S9
4, P ′ 5, P ′ 6, P ′ 8} ◮ ...Clever ratios of angular terms
S.Cunliffe (Imperial) FFP14 Angular analysis of B0 → K∗0µ+µ− 13/21
For B0 → K∗(892)0(→ K±π∓)µ+µ− decays...
◮ P → V V ′ (pseudoscalar to vector-vector) ◮ Vector K∗(892) =
B0 K* 0 K+
π - μ - μ+
θK θℓ φ
◮ 3 angles, and q2
◮ Angular distribution −
T, S9
4, P ′ 5, P ′ 6, P ′ 8} ◮ ...Clever ratios of angular terms
S.Cunliffe (Imperial) FFP14 Angular analysis of B0 → K∗0µ+µ− 13/21
◮ Fit a reduced angular distribution ◮ 3D fit, binned in q2
4, P ′ 5, P ′ 6, P ′ 8
◮ Observe local 3.7σ deviation
◮ Prob. for 24 independent
◮ 1 fb−1 2011 data ]
4
c /
2
[GeV
2
q
5 10 15 20
'
4
P
0.2 0.4 0.6 0.8 1
SM Predictions Data
LHCb
]
4
c /
2
[GeV
2
q
5 10 15 20
'
5
P
0.2 0.4 0.6 0.8 1
SM Predictions Data
LHCb
S.Cunliffe (Imperial) FFP14 Angular analysis of B0 → K∗0µ+µ− 14/21
P ′
5 ⇒ tension in C9
[Phys. Rev. D 88, 074002 (2013)] ◮ Global fit including {P ′ 4, P ′ 5, P ′ 6, P ′ 8} ◮ Fit includes b→ sℓℓ and b→ sγ inputs ◮ 4.5σ discrepancy from SM point ◮ Favours CNP 9
68.3 C.L 95.5 C.L 99.7 C.L Includes Low Recoil data Only 1,6 bins SM
0.15 0.10 0.05 0.00 0.05 0.10 0.15 4 2 2 4 C7
NP
C9
NP
[Eur. Phys. J. C (2013) 73: 2646] ◮ 3σ discrepancy ◮ Differences:
◮ Definitions of observables ◮ Different q2 ranges ◮ Theory assumptions
◮ Best fit is modified C9 ◮ Data described by additional Z′ at ∼ 7TeV ◮ Hard to reconcile with MSSM
3 2 1 1 2 3 3 2 1 1 2 3
ReC9
NP
ReC9
'
FL S4 S5 AFB BK ΜΜ
S.Cunliffe (Imperial) FFP14 Interpretations 15/21
Contributions from new Z′ vector?
[JHEP 1305 (2013) 137)] ◮ Originally motivated {Pi}
◮ Simplification (assumption) in
]
4
c /
2
[GeV
2
q
5 10 15 20
'
5
P
0.2 0.4 0.6 0.8 1
SM Predictions Data
LHCb
[JHEP 1305 (2013) 043] ◮ Uncertainty due to simplified
S.Cunliffe (Imperial) FFP14 Interpretations 16/21
...or underestimated errors
[JHEP 1305 (2013) 137)] ◮ Originally motivated {Pi}
◮ Simplification (assumption) in
]
4
c /
2
[GeV
2
q
5 10 15 20
'
5
P
0.2 0.4 0.6 0.8 1
SM Predictions Data
LHCb
[JHEP 1305 (2013) 043] ◮ Uncertainty due to simplified
]
4
c /
2
[GeV
2
q
5 10 15 20
'
5
P
1
SM arXiv:1303.5794 SM arXiv:1212.2263
LHCb 1fb
ΑΒ;696∀;4∀&3.<∀Χ8D7.∀Ε;∗.∀?∀//<∀−0∃−−!∀Φ!−,#Γ<∀Η9∋Ι&6∀
S.Cunliffe (Imperial) FFP14 Interpretations 16/21
◮ If a Z′ is responsible for P ′ 5 does it
◮ Altmannshofer et al.
[Phys. Rev. D89 (2014) 095033]
◮ Kr¨
uger & Hiller
[Phys.Rev. D69 (2004) 074020] ◮ Experimental challenge:
◮ Selection of B± → K±e+e− ◮ Bremsstrahlung → q2 movement
◮ Correct for bremsstrahlung with
◮ Migration in q2 corrected with
◮ 3 fb−1 2011+2012 data
]
2
c ) [MeV/
−
e
+
e
+
K ( m
5000 5200 5400 5600
)
2
c Candidates / ( 40 MeV/
5 10
3
10 × LHCb (a)
B± → J/ ψ K±
]
2
c ) [MeV/
−
e
+
e
+
K ( m
5000 5200 5400 5600
)
2
c Candidates / ( 40 MeV/
10 20 30 40 LHCb (d)
B± → K±e+e− S.Cunliffe (Imperial) FFP14 Lepton universality in B± → K±ℓ+ℓ− 17/21
◮ Experimentally, use double ratio with B± → J/ψ K± decays
◮ Cancels systematic biases
where Nf is the observed yield for B± → f and ǫf is the corresponding efficiency
◮ RK = 1.000 in SM (argue about
◮ SM Higgs v.suppressed
◮ LHCb measures
−0.074 ± 0.036
◮ In range q2 ∈ [1, 6] GeV2/c4 ◮ Only agrees with SM within 2.6σ
]
4
c /
2
[GeV
2
q
5 10 15 20
K
R
0.5 1 1.5 2 SM
LHCb LHCb
LHCb BaBar Belle
[Phys. Rev. D86 (2012) 032012]
[Phys.Rev.Lett. 103 (2009) 171801]
S.Cunliffe (Imperial) FFP14 Lepton universality in B± → K±ℓ+ℓ− 18/21
3.7 3.8 3.9 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 5.0
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 Rexp Rthe Rcon Rint Rres RBW
R Ecm(GeV) χ
2/d.o.f=1.05
BESII e+e− → hadrons/e+e− → µ+µ−
0.5 1 1.5 2 2.5 3 3.5 3.6 3.8 4 4.2 4.4 4.6
dBr d√ q2 [B+ → K+µµ]/10−7GeV−1
Ψ(3770) Ψ(4040) Ψ(4160) Ψ(4400) a) afac b) ηcafac c) ρr ∈ R d) ρr ∈ C LHCb Ψ(4415) Ψ(2S)
LHCb data: B± → K±µ+µ−, L&Z fits
[arXiv:1406.0566] ◮ Fit BESII and LHCb data ◮ Necessary to add in large corrections (fudge factors) to get good fit ◮ Are we underestimating the non-factorisable effects in Ceff 9 ?
◮ Could explain P ′
5 effect
◮ And/or motivate new physics studies in b→ ccs operators S.Cunliffe (Imperial) FFP14 Something strange from charm 19/21
J/Ψ, Ψ′..
◮ Massively underestimated terms like (a) at low q2 ◮ The green gluons can’t account for this
S.Cunliffe (Imperial) FFP14 Something strange from charm 20/21
◮ FCNC processes probe higher mass scales for NP
◮ Formalism gives model-independence ◮ Observables!
◮ Interesting results in b→ sℓℓ processes
◮ Isospin asymmetry in B → K(∗)µ+µ− ◮ Angular analyses of B0 → K∗0µ+µ− ◮ Lepton universality in B± → K±ℓ+ℓ−
◮ Interest from our theory/phenomenology friends ◮ LHCb data-taking in 2015... ◮ Belle-II physics runs late 2016...
S.Cunliffe (Imperial) FFP14 Conclusions 21/21
ts
iO′ i
7 = e
9 = e2
10 = e2
S.Cunliffe (Imperial) FFP14 Backup 23/21
i
i
i = C′ SM i
i
◮ ∄ right-handed interactions i = 9, 10 operators in SM
9,10 = 0 ◮ ∃ helicity-suppressed right-handed SM contributions to O′ 7 so
7 = ms
7
7
7
S.Cunliffe (Imperial) FFP14 Backup 24/21
The distribution of for vector K∗0(892)
1 sin2 θK + Jc 1 cos2 θK
2 sin2 θK + Jc 2 cos2 θK) cos 2θℓ
FFP14 Backup 25/21
The principle moments
⊥|2 + |AL |2 + |AR ⊥|2 + |AR |2
0 |2 + |AR 0 |2
⊥|2 + |AL |2 + |AR ⊥|2 + |AR |2
0 |2 + |AR 0 |2
⊥|2 − |AL |2 + |AR ⊥|2 − |AR |2
0 AL∗
0 AR∗ )
0 AL∗ ⊥ − AR 0 AR∗ ⊥ )
AL∗ ⊥ − AR AR∗ ⊥ )
0 AL∗
0 AR∗ )
0 AL∗ ⊥ − AR 0 AR∗ ⊥ )
AL ⊥ + AR∗ AR ⊥).
S.Cunliffe (Imperial) FFP14 Backup 26/21
Calculated in the effective field theory
⊥
9
9
10 + Ceff′ 10 )
7
7
B − m2 K∗)
9
9
10 − Ceff′ 10 )
7
7
9
9
10 − Ceff′ 10 )
B − m2 K∗∗ − q2)(mB + mK∗∗)A1(q2) − λ
7
7
B + 3m2 K∗∗ − q2)T2(q2) −
B − m2 K∗∗
S.Cunliffe (Imperial) FFP14 Backup 27/21
Calculated in the effective field theory
ts
F α2
B
B + m4 K∗ + q4 − 2(m2 Bm2 K∗ + m2 K∗q2 + m2 Bq2) and
µ/q2.
S.Cunliffe (Imperial) FFP14 Backup 28/21
i ≡
5 ≡ 1
0 AL∗ ⊥ − AR 0 AR∗ ⊥ )
◮ The asymmetry of the cross term between the longitudinal and
S.Cunliffe (Imperial) FFP14 Backup 29/21