Latest results on
rare decays from LHCb
C. Langenbruch1
on behalf of the LHCb collaboration
1 University
of Warwick
Moriond Electroweak 2015
March 14th − 21st , 2015
Introduction
2 / 28
Rare decays as indirect probes for BSM physics
b
SM penguin diagram
W
t
s(d) b
NP penguin diagram
H±
t
µ+
Z 0, γ
Z 0, γ
s(d)
µ+
µ−
µ−
Rare FCNC decays are loop-suppressed in the Standard Model (SM)
New heavy particles in SM extensions can appear in competing diagrams
can affect B and angular distributions
X
X c
4GF
∗
Heff = − √ Vtb Vtq
Ci Oi + Ci0 Oi0 +
ONP
|{z}
|{z}
Λ2NP
2
i
Left handed Right handed,
ms
suppressed
m
b
i = 1, 2
i = 3 − 6, 8
i=7
i = 9, 10
i = S, P
Model independent description in effective field theory
Wilson coeff. Ci
(0)
(0)
Tree
Gluon penguin
Photon penguin
EW penguin
(Pseudo)scalar penguin
encode short-distance physics, Oi corr. operators
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
Introduction
2 / 28
Rare decays as indirect probes for BSM physics
b
SM penguin diagram
W
t
s(d) b
NP penguin diagram
H±
t
µ+
Z 0, γ
Z 0, γ
s(d)
µ+
µ−
µ−
Rare FCNC decays are loop-suppressed in the Standard Model (SM)
New heavy particles in SM extensions can appear in competing diagrams
can affect B and angular distributions
X
X c
4GF
∗
Heff = − √ Vtb Vtq
Ci Oi + Ci0 Oi0 +
ONP
|{z}
|{z}
Λ2NP
2
i
Left handed Right handed,
ms
suppressed
m
b
i = 1, 2
i = 3 − 6, 8
i=7
i = 9, 10
i = S, P
Model independent description in effective field theory
Wilson coeff. Ci
(0)
(0)
Tree
Gluon penguin
Photon penguin
EW penguin
(Pseudo)scalar penguin
encode short-distance physics, Oi corr. operators
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
Introduction
3 / 28
0
∗0
+ −
+ −
Golden decay B → K [→ K π ]µ µ
d
B0
b̄
d
t̄
s̄
+
µ−
µ
z
B
Z 0, γ
K*
K*
W
Figure 1.
B̄d0 → K̄ ∗0 (→
¯
i) the (``)-in
K
K ∗0
+
+
+
ii) the angle
¯ c
in the (``)
the angle θK
the (K − π + )
between the t
by the 3-mo
¯
(``)-systems,
2
~ = to(θbe` ,on-shell
V is assumed
in theand
narrow-resonance
Decay fully described by three helicity angles
Ω
θK , φ)
q 2 = mapproximati
µµ ¯
of kinematic variables to four4 . Using B̄d0 → K̄ ∗0 (→ K − π + ) + ``
d3 (Γ + Γ̄)
1
9 3
depicted
in figure
1.
2
(1 − FL ) sin2 θK chosen
+The
FLas
cos
θK decay
+ 14 (1
− F ) sin2 θ overcos
2θ
=
2
differential
rate, afterL summing K
lepton `spins, f
~
32π 4
d(Γ + Γ̄)/dq
dΩ
8π2 θ sind2 Γθ cos 2φ s 2
− FL cos2 θK cos 2θ` + S3 sin
`
K
= J1 sin θK + J1c cos2 θK
3 dq 2 d cos θ` d cos θK dφ
+ S4 sin 2θK sin 2θ` cos φ + S5 sin 2θK+J
sin
θ2 cos φ2
3 sin `θK sin θ` cos 2φ + J4 sin 2θK
4
∗
∗
∗
+ 34 AFB sin2 θK cos θ` + S7 sin 2θK sin θ` sin φ
2
2
+ (J2s sin2
sin 2θ` cos
+(J6s sin2 θK ∗ + J6c cos2 θK ∗ ) cos
+ S8 sin 2θK sin 2θ` sin φ + S9 sin θK sin θ` sin 2φ
+J8 sin 2θK ∗ sin 2θ` sin φ
that is, into q 2 -dependent observables5 Jij (q 2 ) and the depende
φ. No additional angular dependencies can be induced by any
(0)basis [11]
(0)as found by [12, 13]. The following simplifications arise
9 J c = −J
10
c
c
1
2 and J6 = 0.
The differential decay rate d4 Γ̄ of the CP-conjugated decay
obtained through the following replacements
FL , AFB , Si combinations of K ∗0 spin amplitudes
(0)
depending on Wilson coefficients C7 , C , C
Large part of theory uncertainty due to hadronic form-factors
C. Langenbruch (Warwick), Moriond EW 2015
∗
∗
Jj
→ J¯j
Rare decays 1,2,3,4,7
from LHCb1,2,3,4,7
[δW → −δW ],
j
j
J5,6,8,9
→ − J¯5,6,8
Introduction
4 / 28
Reminder: B → K µ µ angular observables (1 fb−1 )
∗0 + −
1
Theory
LHCb
Binned
AFB
FL
0
LHCb
0.8
1
Theory
LHCb
Binned
LHCb
0.5
0.6
0
0.4
-0.5
0.2
0
0
5
10
15
20
q 2 [GeV2/ c 4]
-1
0
5
10
15
20
q 2 [GeV2/ c 4]
[JHEP 08 (2013) 131]
Angular observables in good agreement with
SM prediction [C. Bobeth et al. JHEP 07 (2011) 067]
Zero crossing point of AFB free from FF uncertainties
Result q02 = 4.9 ± 0.9 GeV2 consistent with SM prediction
2
2
q0,SM
= 4.36+0.33
−0.31 GeV [EPJ C41 (2005) 173-188]
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
Introduction
5 / 28
Less form factor dependent observables
P 4'
−1
(1 fb )
Less FF dependent observables Pi0 introduced in [JHEP 05 (2013) 137]
p
0
= S4,5 / FL (1 − FL ) leading FF uncertainties cancel for all q 2
For P4,5
3.7σ local deviation from SM prediction [JHEP 05 (2013) 137] in P50
1
0.8
SM Predictions
0.6
0.4
P 5'
Pi0
LHCb
1
0.8
Data
SM Predictions
0.4
0.2
Data
0.2
0
0
-0.2
-0.2
-0.4
-0.4
-0.6
-0.6
-0.8
-0.8
-1
0
LHCb
0.6
5
10
15
20
-1
0
3.7σ
5
q 2 [GeV2/c 4]
10
15
20
q 2 [GeV2/c 4]
[PRL 111, 191801 (2013)]
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
Introduction
6 / 28
+ −
LCSR
3
2
1
0
0
5
10
15
20
Data
B0→ K 0µ +µ −
LHCb
4
3
2
1
0
0
5
10
15
20
Lattice
15
10
5
0
0
5
10
15
q2 [GeV2/c4]
20
q2 [GeV2/c4]
Measured B 0 → (K ∗0 , K 0 )µ+ µ− , B + → (K + , K ∗+ )µ+ µ− , Bs0 → φµ+ µ−
[JHEP 08 (2013) 131] [JHEP 06 (2014) 133] [JHEP 07 (2013) 084]
Data
B+→ K *+µ +µ −
LHCb
Average of LHCb,
CDF, CMS, ATLAS
q2 [GeV2/c4]
LCSR
20
Average of LHCb, CDF
4
Lattice
5
[PRL 112, 212003]
Data
B+→ K +µ +µ −
LHCb
dB/dq2 [10-8 × c4/GeV2]
Lattice
dB/dq2 [10-8 × c4/GeV2]
dB/dq2 [10-8 × c4/GeV2]
LCSR
5
B tend to lie below SM predictions
[Horgan et al., PRL 112, 212003] [Altmannshofer et al. arxiv:1411.3161]
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
[JHEP 06 (2014) 133]
b → sµ µ branching fractions
Introduction
7 / 28
The global picture of b → s transitions
[PRD 88, 074002]
[arxiv:1411.3161]
Global b → s
Only K ∗0 µµ
Only B
Global fits to b → s FCNC processes prefer shift of C9 by ∼ −1.5
[S. Descotes-Genon et al. PRD 88, 074002] [Altmannshofer et al. arxiv:1411.3161]
[Beaujean et al. EPJC 74 2897] [Hurth et al. JHEP 04 097]
Consistent picture of the observed tensions in angular obs. and B
Possible NP interpretation: Z 0
[Gauld et al., arxiv:1310.1082] [Buras et al., arxiv:1311.6729]
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
Introduction
8 / 28
Another interesting deviation: RK
u
B+
b̄
RK
LHCb
u
K+
t̄
BaBar
Belle
2
LHCb
1.5
s̄
W+
Z 0, γ
1
SM
µ− /e−
0.5
µ+ /e+
0
0
5
10
15
20
q2 [GeV2/ c4]
B(B + →K + µ+ µ− ) SM
=
B(B + →K + e+ e− )
1 ± O(10−3 )
Test of lepton universality: RK =
RK = 0.745+0.090
−0.074 (stat.) ± 0.036(syst.), compatible with SM at 2.6σ
Can also be explained in a consistent way
[Hiller et al., PRD 90, 054014 (2014)] [Altmannshofer et al., PRD 89 (2014) 095033]
[Glashow et al., PRL 114, 091801 (2015)] [Crivellin et al., arxiv:1501.00993]
See also talk by A. Crivellin
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
Latest results on rare decays
9 / 28
Latest results
t
t
W
t
W
Z 0, γ
b
s
W
Z 0, γ
b
µ
µ
t
s
W
Z 0, γ
b
µ
µ
t
s
W
Z 0, γ
b
µ
C. Langenbruch (Warwick), Moriond EW 2015
µ
t
s
W
Z 0, γ
b
µ
µ
s
Z 0, γ
b
µ
Rare decays from LHCb
µ
µ
µ
s
Latest results on rare decays
10 / 28
0
B(s)
Study of rare
+ − + −
→ π π µ µ decays I
s
s
Bs0
t̄
b̄
d
f0
s̄
W+
Z 0, γ
d
B0
t̄
b̄
W+
Z 0, γ
µ−
µ+
Bs0 → f0 µ+ µ− : b → s transition similar to B 0 → K ∗0 µ+ µ−
B 0 → ρ0 µ+ µ− : b → d transition, |Vtd /Vts |2 suppressed in SM
SM predictions show large variation
BSM (Bs0 → f0 µ+ µ− ) = 0.6 × 10−9 − 5.2 × 10−7
BSM (B 0 → ρ0 µ+ µ− ) = (5 − 9) × 10−8
[PRD 79 014013], [PRD 81 074001], [PRD 80 016009]
[PRD 56 5452-5465], [Eur.Phys.J.C 41 173-188]
C. Langenbruch (Warwick), Moriond EW 2015
µ−
µ+
Contributions from
ρ0
¯
d
Rare decays from LHCb
Latest results on rare decays
+ − + −
→ π π µ µ decays II
Signal decay
Events/(20 MeV/c2)
Events/(20 MeV/c2)
Resonant decay
B0s→ J/ψ π+ πB0→ J/ψ π+ π0
0
B → J/ψ K*(892)
Bs0 → J/ψ φ
0
Bs → J/ψ η’
B+→ J/ψ K+
Combinatorial
+
+
Bc → J/ψ π π-π+
Total fit
103
102
LHCb
40
B0s→ π+ π- µ+ µB0→ π+ π- µ+ µ0
0
B → K*(892) µ+ µB0s → η’ µ+ µ-
30
Combinatorial
Total fit
20
LHCb
10
10
5.2
[PLB 743 (2015) 46]
Study of rare
11 / 28
0
B(s)
5.6
5.8
5.2
5.4
5.6
5.8
M(π+π-µ+µ-) [GeV/c2]
M(π+π-µ+µ-) [GeV/c2]
Observation of Bs0 → π + π − µ+ µ− with 7.6σ
0
+ − + −
5.4
Evidence for B → π π µ µ
with 4.8σ
Branching fractions compatible with SM predictions
B(Bs0 → π + π − µ+ µ− ) = (8.6 ± 1.5stat. ± 0.7syst. ± 0.7norm. ) × 10−8
B(B 0 → π + π − µ+ µ− ) = (2.11 ± 0.51stat. ± 0.15syst. ± 0.16norm. ) × 10−8
Motivated work in theory
[Wang et al., arxiv:1502.05104], [arxiv:1502.05483]
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
Latest results on rare decays
12 / 28
The rare decay
Λ0b
+ −
→ Λµ µ
u
u
Λb d
b
d Λ
t
s
W
Z 0, γ
µ−
µ+
Rare Λ0b baryon decays have unique features
1 Λ0b has half-integer spin
2 Particular hadronic dynamics (heavy quark + light di-quark system)
3 Λ decays weakly [JHEP 01 (2015) 155]
Measured angular obs. and B
[LHCb-PAPER-2015-009, to be submitted to JHEP]
Presentation by L. Pescatore this afternoon
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
Latest results on rare decays
13 / 28
∗0 + −
0
The rare decay B → K e e
J/ψ(1S)
d
B0
b̄
d
t̄
W+
Z 0, γ
K ∗0
s̄
ψ(2S)
(!)
dΓ
dq 2
C7
(!)
(!)
C7 C9
e−
!"#$%&$%$"'$(
(!)
C9
(!)
)"*( C 10
+,"-(*!.#)"'$(
',"#%!/01,".(&%,2(cc̄
)/,3$(,4$"('5)%2(
#5%$.5,6*((
e+
4 [m(µ)]22
4[m(`)]
Analyse B 0 → K ∗0 e+ e− at very low q 2 : [0.0004, 1.0] GeV2/c4 ,
accessible due to tiny e mass
Im
Determine angular observables FL , AT , ARe
T , AT
0
sensitive to C7 and C7
Experimental challenges: Trigger and Bremsstrahlung
(2)
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
q2
Latest results on rare decays
13 / 28
∗0 + −
0
The rare decay B → K e e
d
B0
b̄
d
t̄
W+
Z 0, γ
K ∗0
s̄
e−
e+
Candidates / (30 MeV/c2)
[arxiv:1501.03038]
30
B0 → K*0e+e−
B →(K*0X)e+e−
Combinatorial
Data
Model
25
LHCb
20
15
10
5
0
4800
5000
5200
Analyse B 0 → K ∗0 e+ e− at very low q 2 : [0.0004, 1.0] GeV2/c4 ,
accessible due to tiny e mass
Im
Determine angular observables FL , AT , ARe
T , AT
0
sensitive to C7 and C7
Experimental challenges: Trigger and Bremsstrahlung
(2)
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
5400
m(K+π−e+e−) [MeV/c2]
Latest results on rare decays
14 / 28
∗0 + −
0
40
30
20
Candidates / (0.1π rad)
LHCb
50
Candidates / (0.2)
Candidates / (0.2)
Angular analysis of B → K e e decays
LHCb
40
35
30
25
20
15
10
10
-0.5
0
0.5
cos θl
0
-1
[arxiv:1501.03038]
result
obs.
FL
+0.16 ± 0.06 ± 0.03
(2)
AT
−0.23 ± 0.23 ± 0.05
ARe
+0.10 ± 0.18 ± 0.05
T
AIm
+0.14 ± 0.22 ± 0.05
T
25
20
15
10
-0.5
0
0.5
1
cos θK
0
0
1
2
[JHEP 05 (2013) 043]
obs.
SM prediction
FL
(2)
AT
ARe
T
AIm
T
+0.10+0.11
−0.05
+0.03+0.05
−0.04
−0.15+0.04
−0.03
−4
(−0.2+1.2
−1.2 ) × 10
Results are in good agreement with SM predictions
Constraints on C7 competitive with radiative decays
(0)
C. Langenbruch (Warwick), Moriond EW 2015
LHCb
30
5
5
0
35
Rare decays from LHCb
3
∼
φ [rad]
B 0 → K ∗0 µ+ µ−
15 / 28
−1
∗0 + −
0
Angular analysis of B → K µ µ using 3 fb
PV
SV
µ
µ
π
K
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
B 0 → K ∗0 µ+ µ−
0
16 / 28
∗0 + −
q2 [GeV2/c4]
B → K µ µ selection
[LHCb-CONF-2015-002]
20
LHCb
preliminary
18
16
104
14
103
12
10
102
8
6
10
4
2
0
5.2
5.3
5.4
5.5
5.6
5.7
1
m(K + -µ +µ -) [GeV/c2]
BDT to suppress combinatorial background
Input variables: PID, kinematic and geometric quantities, isolation variables
Veto of B 0 → J/ψ K ∗0 and B 0 → ψ(2S)K ∗0 (important control decays)
and peaking backgrounds using kinematic variables and PID
Signal clearly visible as vertical band after the full selection
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
B 0 → K ∗0 µ+ µ−
17 / 28
0
∗0 + −
Mass model and B → K µ µ signal yield
LHCb
preliminary
100
B 0 → K ∗0 µµ signal
1.1 < q 2 < 6.0 GeV2/c4
50
Events / 5.3 MeV/c2
Events / 5.3 MeV/c2
[LHCb-CONF-2015-002]
LHCb
preliminary
104
B 0 → J/ψ K ∗0
control decay
103
102
0
5200
5400
5600
m(K +π −µ +µ −) [MeV/c2]
5200
5400
5600
m(K +π −µ +µ −) [MeV/c2]
Signal mass model from high statistics B 0 → J/ψ K ∗0
Correction factor from simulation to account for q 2 dep. resolution
Finer q 2 binning to allow more flexible use in theory
Significant signal yield in all bins, q 2 integrated Nsig = 2398 ± 57
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
B 0 → K ∗0 µ+ µ−
17 / 28
∗0 + −
0
20
40
LHCb
preliminary
30
20
30
[LHCb-CONF-2015-002]
[2.5, 4.0] GeV2/c4
[4.0, 6.0] GeV2/c4
Events / 5.3 MeV/c2
LHCb
preliminary
40
[1.1, 2.5] GeV2/c4
Events / 5.3 MeV/c2
[0.1, 0.98] GeV2/c4
Events / 5.3 MeV/c2
Events / 5.3 MeV/c2
Mass model and B → K µ µ signal yield
LHCb
preliminary
20
10
LHCb
preliminary
40
20
10
2
Events / 5.3 MeV/c2
0
5600
m(K +π −µ +µ −) [MeV/c2]
[6.0, 8.0] GeV /c
4
LHCb
preliminary
60
40
20
0
5200
5400
0
5600
m(K +π −µ +µ −) [MeV/c2]
2
[11.0, 12.5] GeV /c
4
LHCb
preliminary
40
20
5200
5400
0
5600
m(K +π −µ +µ −) [MeV/c2]
2
[15.0, 17.0] GeV /c
4
LHCb
preliminary
60
40
5200
5400
5600
m(K +π −µ +µ −) [MeV/c2]
[17.0, 19.0] GeV2/c4
Events / 5.3 MeV/c2
5400
Events / 5.3 MeV/c2
5200
Events / 5.3 MeV/c2
0
LHCb
preliminary
40
20
20
5200
5400
5600
m(K +π −µ +µ −) [MeV/c2]
0
5200
5400
5600
m(K +π −µ +µ −) [MeV/c2]
0
5200
5400
5600
m(K +π −µ +µ −) [MeV/c2]
0
5200
5400
5600
m(K +π −µ +µ −) [MeV/c2]
Signal mass model from high statistics B 0 → J/ψ K ∗0
Correction factor from simulation to account for q 2 dep. resolution
Finer q 2 binning to allow more flexible use in theory
Significant signal yield in all bins, q 2 integrated Nsig = 2398 ± 57
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
B 0 → K ∗0 µ+ µ−
18 / 28
Acceptance effect
1
0.5
[0.1, 1.0] GeV2/c4
[18.0, 19.0] GeV2/c4
1
0.5
LHCb
simulation
0
-1
-0.5
Efficiency
Efficiency
Efficiency
[LHCb-CONF-2015-002]
1
0.5
LHCb
simulation
0
0.5
1
cos θ l
0
-1
-0.5
LHCb
simulation
0
0.5
1
0
cos θ K
-2
0
2
φ
Trigger, reconstruction and selection distorts decay angles and q 2 distribution
Parametrize 4D efficiency using Legendre polynomials Pk
X
cklmn Pk (cos θ` )Pl (cos θK )Pm (φ)Pn (q 2 )
ε(cos θ` , cos θK , φ, q 2 ) =
klmn
Coefficients cklmn from moments analysis of B 0 → K ∗0 µ+ µ− PHSP MC
Crosscheck acceptance using B 0 → J/ψ K ∗0 control decay
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
B 0 → K ∗0 µ+ µ−
19 / 28
0
LHCb
preliminary
LHCb
preliminary
4000
50
5200
5400
0
5600
-1
m(K +π −µ +µ −) [MeV/c2]
LHCb
preliminary
8000
6000
4000
-0.5
0
0.5
1
cos θ l
LHCb
preliminary
4000
2000
2000
0
-1
-0.5
0
0.5
1
cos θ K
0
-2
0
2
[LHCb-CONF-2015-002]
2000
0
Events / 0.02
×103
Events / 0.02
100
Events / 0.02 π rad
Events / 5.3 MeV/c2
Control decay B → J/ψ K
∗0
φ [rad]
black line: full fit, blue: signal component, red: bkg. part
Angular observables successfully reproduced [PRD 88, 052002 (2013)]
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
B 0 → K ∗0 µ+ µ−
20 / 28
S-wave pollution
S-wave: K + π − not from K ∗0 (892) but in spin 0 configuration
Introduces two add. decay amplitudes resulting in six add. observables
1
d3 (Γ + Γ̄) 1
d3 (Γ + Γ̄) =(1
−
F
)
S
~
~
d(Γ + Γ̄)/dq 2
d(Γ + Γ̄)/dq 2
dΩ
dΩ
S+P
P
3
2
FS sin θ` + S-P interference
+
16π
FS scales P-wave observables, needs to be determined precisely
Perform simultaneous mKπ
fit to constrain FS
P-wave described by rel. BW
S-wave described by LASS model
crosschecked using Isobar param.
Events / 10 MeV/c2
[LHCb-CONF-2015-002]
40000
20000
0
0.8
C. Langenbruch (Warwick), Moriond EW 2015
LHCb
preliminary
60000
Rare decays from LHCb
0.85
0.9
0.95
m(K +π −) [GeV/c2]
B 0 → K ∗0 µ+ µ−
0
21 / 28
∗0 + −
B → K µ µ Likelihood fit
Full 3 fb−1 allows first simultaneous determination of all eight
CP-averaged observables in a single fit
Allows to quote correlation matrix to include in global fit
Perform maximum likelihood fit to the decay angles and mKπµµ in q 2
bins, simultaneously fitting mKπ to constrain FS
h
X
~ q 2 )fsig Psig (Ω)P
~ sig (mKπµµ )
log L =
log (Ω,
i
i
~ bkg (mKπµµ )
+ (1 − fsig )Pbkg (Ω)P
h
i
X
+
log fsig Psig (mKπ ) + (1 − fsig )Pbkg (mKπ )
i
Psig (Ω) given by
d3 (Γ+Γ̄) 1
~
d(Γ+Γ̄)/dq 2
dΩ
S+P
nd
Pbkg (Ω) modelled with 2
order Chebychev polynomials.
Feldman-Cousins method [G. Feldman et al., PRD 57 3873-3889]
to ensure correct coverage at low statistics
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
B 0 → K ∗0 µ+ µ−
22 / 28
Systematic uncertainties
1 Systematic uncertainties related to acceptance:
Kinematic differences between data and simulation
q 2 dependence of acceptance
Acceptance model (order of parametrisation)
statistical uncertainty
2 Peaking backgrounds
−
Bs0 → φµ+ µ− , Λ0b → pKµ+ µ− , B 0 → K + πrndm.
µ+ µ−
3 PDF modeling
Signal mass model
Angular background model
mKπ S-wave description (LASS/Isobar)
mKπ dependent efficiency
All determined using high statistics toys
Measurement is statistically dominated
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
B 0 → K ∗0 µ+ µ−
22 / 28
Systematic uncertainties
1 Systematic uncertainties related to acceptance:
Kinematic differences between data and simulation . 0.01 − 0.02
q 2 dependence of acceptance
Acceptance model (order of parametrisation) . 0.01
statistical uncertainty
2 Peaking backgrounds
−
Bs0 → φµ+ µ− , Λ0b → pKµ+ µ− , B 0 → K + πrndm.
µ+ µ− . 0.01 − 0.02
3 PDF modeling
Signal mass model
Angular background model
mKπ S-wave description (LASS/Isobar)
mKπ dependent efficiency
All determined using high statistics toys
Measurement is statistically dominated
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
B 0 → K ∗0 µ+ µ−
23 / 28
∗0 + −
LHCb
preliminary
60
Events / 0.1 π
Events / 0.1
B → K µ µ likelihood projections [1.1, 6.0] GeV2/c4
Events / 0.1
0
LHCb
preliminary
100
40
LHCb
preliminary
60
40
50
20
0.5
-0.5
LHCb
preliminary
100
50
0
0
-1
1
cos θ l
5200
5400
5600
m(K +π −µ +µ −) [MeV/c2]
0
0.5
0
1
cos θ K
-2
LHCb
preliminary
100
50
0
0.8
0.85
0.9
0.95
m(K +π −) [GeV/c2]
Efficiency corrected distributions show good agreement
with overlaid PDF projections
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
0
[LHCb-CONF-2015-002]
0
Events / 10 MeV/c2
-0.5
Events / 5.3 MeV/c2
0
-1
20
2
φ [rad]
B 0 → K ∗0 µ+ µ−
24 / 28
∗0 + −
0
1
S3
FL
B → K µ µ Results: FL , S3 , S4 , S5
0.8
LHCb
preliminary
0.6
[1503.05534][1411.3161]
0.5
LHCb
preliminary
SM from ABSZ
SM from ABSZ
[1503.05534][1411.3161]
0
0.4
0.2
-0.5
5
10
15
0
5
10
0.5
LHCb
preliminary
0.5
LHCb
preliminary
SM from ABSZ
SM from ABSZ
[1503.05534][1411.3161]
0
[1503.05534][1411.3161]
0
-0.5
0
15
q2 [GeV2/ c4]
S5
S4
q2 [GeV2/ c4]
-0.5
5
10
15
0
5
q2 [GeV2/ c4]
C. Langenbruch (Warwick), Moriond EW 2015
10
15
q2 [GeV2/ c4]
Rare decays from LHCb
[LHCb-CONF-2015-002]
0
0
B 0 → K ∗0 µ+ µ−
25 / 28
∗0 + −
0
S7
A FB
B → K µ µ Results: AFB , S7 , S8 , S9
0.5
0
0.5
LHCb
preliminary
0
LHCb
preliminary
SM from ABSZ
0
-0.5
[1503.05534][1411.3161]
5
10
15
0
5
10
0.5
LHCb
preliminary
0
0.5
LHCb
preliminary
0
-0.5
0
15
q2 [GeV2/ c4]
S9
S8
q2 [GeV2/ c4]
-0.5
5
10
15
0
5
q2 [GeV2/ c4]
C. Langenbruch (Warwick), Moriond EW 2015
10
15
q2 [GeV2/ c4]
Rare decays from LHCb
[LHCb-CONF-2015-002]
-0.5
B 0 → K ∗0 µ+ µ−
26 / 28
Forward-backward asymmetry AFB
A FB
[LHCb-CONF-2015-002]
0.5
0
LHCb
preliminary
SM from ABSZ
-0.5
0
[1503.05534][1411.3161]
5
10
15
q2 [GeV2/ c4]
Data points slightly below SM prediction at low q 2
2 4
ZCP q02 = 3.7+0.8
−1.1 GeV /c evaluated as in [JHEP 08 (2013) 131]
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
B 0 → K ∗0 µ+ µ−
27 / 28
P50
5
P'
[LHCb-CONF-2015-002]
1
LHCb
preliminary
0.5
SM from DHMV
[1407.8526]
0
-0.5
-1
0
5
10
15
q2 [GeV2/ c4]
Tension seen in P50 in [PRL 111, 191801 (2013)] confirmed
[4.0, 6.0] and [6.0, 8.0] GeV2/c4 show deviations of 2.9σ each
Naive combination results in a significance of 3.7σ
Compatible with 1 fb−1 measurement
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
B 0 → K ∗0 µ+ µ−
27 / 28
P50
5
P'
[LHCb-CONF-2015-002]
1
LHCb
preliminary
0.5
SM from DHMV
[1407.8526]
0
-0.5
-1
0
5
10
15
q2 [GeV2/ c4]
Tension seen in P50 in [PRL 111, 191801 (2013)] confirmed
[4.0, 6.0] and [6.0, 8.0] GeV2/c4 show deviations of 2.9σ each
Naive combination results in a significance of 3.7σ
Compatible with 1 fb−1 measurement
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
Conclusions
28 / 28
Conclusions
Rare decays are an excellent laboratory to search for BSM effects
LHCb an ideal environment to study these decays
Presented full angular analysis of B 0 → K ∗0 µ+ µ−
using the full 3 fb−1 LHCb data sample
P50 deviation confirmed:
Two q 2 bins with significance of 2.9σ each
More interesting tensions in electroweak penguins:
RK , low b → sµµ B
Looking forward to the theory interpretation!
See talks by Q. Matias, D. Straub
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
Backup
29 / 28
Non Standard Model Penguin?
[Nature Methods 11, 1242–1244 (2014)]
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
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30 / 28
The LHC as heavy flavour factory
bb̄ polar angles
bb̄ produced correlated predominantly in forward (backward) direction
→ single arm forward spectrometer (2 < η < 5)
Large bb̄ production cross section
σbb̄ = (75.3 ± 14.1) µb [Phys.Lett. B694 (2010)] in acceptance
∼ 1 × 1011 produced bb̄ pairs in 2011, excellent environment to study
B 0 → K ∗0 µ+ µ− and other rare decays
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
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31 / 28
The LHCb detector: Tracking
Tracking system
Vertex
detector
B 0 → K ∗0 µ+ µ− signature
L ∼ 7 mm SV
B0
PV
Interaction
point
p
−
µ+ π
µ−
K+
p
IP
Excellent Impact Parameter (IP) resolution (20 µm)
→ Identify secondary vertices from heavy flavour decays
Proper time resolution ∼ 40 fs
→ Good separation of primary and secondary vertices
Excellent momentum (δp/p ∼ 0.4 − 0.6%) and inv. mass resolution
→ Low combinatorial background
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
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32 / 28
The LHCb detector: Particle identification and Trigger
Muon system
RICH2
K/π separation
[arxiv:1211.6759]
RICH1
Excellent Muon identification µ→µ ∼ 97% π→µ ∼ 1-3%
Good Kπ separation via RICH detectors K→K ∼ 95% π→K ∼ 5%
→ Reject peaking backgrounds
High trigger efficiencies, low momentum thresholds
Muons: pT > 1.76 GeV at L0, pT > 1.0 GeV at HLT1
B → J/ψ X: Trigger ∼ 90%
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
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33 / 28
Data taken by LHCb
Published results I will discuss today only use 1 fb−1 taken in 2011
Full data sample of 3 fb−1 currently under study
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
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The very rare decay
34 / 28
Bs0 →
+ −
µ µ
Observation of Bs0 → µ+ µ− using combined CMS and LHCb
dataset [arxiv:1411.4413], submitted to Nature
+0.26
−9
B(Bs0 → µ+ µ− ) = (2.79+0.66
, 6.2σ sign. (7.6σ expected)
−0.60 −0.19 ) × 10
+1.58 +0.31
0
+ −
−10
B(B → µ µ ) = (3.94−1.41 −0.24 ) × 10 , 3.2σ sign. (0.8σ expected)
SM predictions [Bobeth et al., PRL 112 (2014) 101801]
B(Bs0 → µ+ µ− ) = (3.66 ± 0.23) × 10−9 , compatible at 1.2σ
B(B 0 → µ+ µ− ) = (1.06 ± 0.09) × 10−10 , compatible at 2.2σ
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
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0
35 / 28
∗0 + −
B → K µ µ angular observables
Four-differential decay rate for B 0 → K ∗0 µ+ µ−
9 s 2
d4 Γ(B 0 → K ∗0 µ+ µ− )
=
I sin θK + I1c cos2 θK
dq 2 d cos θ` d cos θK dφ
32π 1
+ (I2s sin2 θK + I2c cos2 θK ) cos 2θ`
+ I3 sin2 θK sin2 θ` cos 2φ + I4 sin 2θK sin 2θ` cos φ
+ I5 sin 2θK sin θ` cos φ
+ (I6s sin2 θK + I6c cos2 θK ) cos θ` + I7 sin 2θK sin θ` sin φ
+ I8 sin 2θK sin 2θ` sin φ + I9 sin2 θK sin2 θ` sin 2φ
(0)
(0)
(0)
Ii (q 2 ) combinations of K ∗0 spin amplitudes sensitive to C7 , C9 , C10
Γ̄)
¯ d(Γ+Γ̄)
CP-averages Si = (Ii + I¯i )/ d(Γ+
dq 2 , CP-asymmetries Ai = (Ii − Ii )/ dq 2
For m` = 0: 8 CP averages Si , 8 CP-asymmetries Ai
Simultaneous fit of 8 observables not possible with the 2011 data set
→ Angular folding φ → φ + π for φ < 0 cancels terms ∝ sin φ, cos φ
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
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0
35 / 28
∗0 + −
B → K µ µ angular observables
Four-differential decay rate for B 0 → K ∗0 µ+ µ−
9 s 2
d4 Γ(B 0 → K ∗0 µ+ µ− )
=
I sin θK + I1c cos2 θK
dq 2 d cos θ` d cos θK dφ
32π 1
+ (I2s sin2 θK + I2c cos2 θK ) cos 2θ`
((
((
(2θ
+ I3 sin2 θK sin2 θ` cos 2φ + I4 (
sin(2θ
sin
(K(
` cos φ
(
((
(θ(
+ I5 (
sin 2θ (
sin
` cos φ
( ((K
((
(θ(
(K(
+ (I6s sin2 θK + I6c cos2 θK ) cos θ` + (
I7 (
sin(2θ
sin
` sin φ
(
(
((
2
2
(2θ
+ I8 (
sin 2θ (
sin
` sin φ + I9 sin θK sin θ` sin 2φ
( ((K
(0)
(0)
(0)
Ii (q 2 ) combinations of K ∗0 spin amplitudes sensitive to C7 , C9 , C10
Γ̄)
¯ d(Γ+Γ̄)
CP-averages Si = (Ii + I¯i )/ d(Γ+
dq 2 , CP-asymmetries Ai = (Ii − Ii )/ dq 2
For m` = 0: 8 CP averages Si , 8 CP-asymmetries Ai
Simultaneous fit of 8 observables not possible with the 2011 data set
→ Angular folding φ → φ + π for φ < 0 cancels terms ∝ sin φ, cos φ
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
Backup
2
Ii (q ) depend on K
∗0
spin amplitudes
AL,R
0 ,
4m2µ
(2 + βµ2 ) L 2
2
R∗
L R∗
|A⊥ | + |AL
<(AL
⊥ A⊥ + Ak Ak )
k | + (L → R) +
4
q2
4m2µ 2
R 2
R∗
I1c = |AL
|At |2 + 2<(AL
0 A0
0 | + |A0 | +
q2
βµ2
2
L 2
|AL
I2s =
⊥ | + |Ak | + (L → R)
4
c
2
I2 = −βµ2 |AL
0 | + (L → R)
For completeness
I1s =
βµ2
2
L 2
|AL
⊥ | − |Ak | + (L → R)
2
βµ2
L∗
= √ <(AL
0 Ak ) + (L → R)
2
√
L∗
= 2βµ <(AL
0 A⊥ ) − (L → R)
L∗
= 2βµ <(AL
k A⊥ ) − (L → R)
√
L∗
= 2βµ =(AL
0 Ak ) − (L → R)
I3 =
I4
I5
I6
I7
βµ2
L∗
I8 = √ =(AL
0 A⊥ ) + (L → R)
2
2
L
I9 = βµ =(AL∗
k A⊥ ) + (L → R)
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
AL,R
k ,
36 / 28
AL,R
⊥
Backup
K
∗0
spin amplitudes
AL,R
0 ,
AL,R
k ,
AL,R
⊥
37 / 28
√
V(q2 )
2mb
0eff
eff
0eff
0eff
2
= N 2λ (Ceff
+ 2 (Ceff
9 + C9 ) ∓ (C10 + C10 )
7 + C7 )T1 (q )
mB + mK ∗
q
√
A1 (q2 )
2mb
L(R)
0eff
2
0eff
eff
0eff
+ 2 (Ceff
Ak
= −N 2(m2B − m2K ∗ ) (Ceff
7 − C7 )T2 (q )
9 − C9 ) ∓ (C10 − C10 )
mB − mK ∗
q
eff
2
N
A2 (q2 ) L(R)
eff
0eff
2
2
p
A0
=−
(C9 − C0eff
)
∓
(C
−
C
)
(m
−
m
−
q
)(m
+ mK ∗ )A1 (q2 ) − λ
∗
B
9
10
10
B
K
2
m
∗
B + mK ∗
2mK q
2
λ
eff
0eff
2
2
2
+ 2mb (C7 − C7 ) (mB + 3mK ∗ − q )T2 (q ) − 2
T3 (q )
mB − m2K ∗
L(R)
For completeness
A⊥
(0)eff
Wilson coefficients C7,9,10
Seven form factors (FF) V (q 2 ), A0,1,2 (q 2 ), T1,2,3 (q 2 )
encode hadronic effects and require non-perturbative calculation
Low q 2 ≤ 6 GeV2
→ ξ⊥,k (soft form factors)
Large q 2 ≥ 14 GeV2
→ f⊥,k,0 (helicity form factors)
Theory uncertainties:
FF from non-perturbative calculations
Λ/mb corrections (“subleading corrections”)
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
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38 / 28
m(µ+µ−) [MeV/c2]
Analysis strategy
LHCb
Resonant decays
4000
103
3000
Signal band
10
1000
5200
5400
1
5600
m(K+π−µ+µ−)
J/ψ , ψ(2S) band
102
2000
0
104
[MeV/c2]
Veto of B 0 → J/ψ K ∗0 and B 0 → ψ(2S)K ∗0 (valuable control channels!)
Suppression of peaking backgrounds with PID
Rejection of combinatorial background with BDT
1 Determine the differential branching fraction in q 2 bins
2 Determine angular observables in multidimensional likelihood fit
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
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∗0 + −
0
Signal
Combinatorial bkg
20
Candidates / ( 10 MeV/c 2 )
0
Peaking bkg
5200
5400
LHCb
2
10.09 < q < 12.86 GeV
2
/c4
40
20
5200
5400
2 < q2 < 4.3 GeV2/ c 4
40
20
0
5600
60
0
LHCb
m(K π−µ+µ−) [MeV/c2]
+
5600
m(K π−µ+µ−) [MeV/c2]
+
5200
5400
+
LHCb
2
14.18 < q < 16 GeV
2
20
5400
4.3 < q2 < 8.68 GeV2/ c 4
20
+
5600
5200
Use B 0 → J/ψ K ∗0 as normalisation channel
+
LHCb
16 < q2 < 19 GeV2/ c 4
20
0
5200
SM prediction [C. Bobeth et al. JHEP 07 (2011) 067]
Data somewhat low but large theory uncertainties due to FF
C. Langenbruch (Warwick), Moriond EW 2015
5600
m(K π−µ+µ−) [MeV/c2]
40
2
5400
60
m(K π−µ+µ−) [MeV/c2]
Fit of Nsig in q bins
/c4
40
5200
LHCb
40
0
5600
60
0
60
m(K π−µ+µ−) [MeV/c2]
Candidates / ( 10 MeV/c 2 )
0.1 < q2 < 2 GeV2/ c 4
40
60
Candidates / ( 10 MeV/c 2 )
LHCb
Candidates / ( 10 MeV/c 2 )
60
Candidates / ( 10 MeV/c 2 )
Candidates / ( 10 MeV/c 2 )
B → K µ µ signal yield (2011)
Rare decays from LHCb
5400
5600
m(K π−µ+µ−) [MeV/c2]
+
Backup
39 / 28
∗0 + −
0
Signal
Combinatorial bkg
Peaking bkg
5200
5400
+
1
60
LHCb
2
0.5
10.09 < q < 12.86 GeV
40
0
5600
2
/c4
0
0
20
LHCb
20
m(K π−µ+µ−) [MeV/c2]
Candidates / ( 10 MeV/c 2 )
20
0
Candidates / ( 10 MeV/c 2 )
1.5
Theory
40
LHCb
LHCb
Binned
2 < q2 < 4.3 GeV2/ c 4
5200
5400
+
2
14.18 < q < 16 GeV
2
5200
5400
5600
m(K π−µ+µ−) [MeV/c2]
+
/c4
40
10
15
0
5200
5400
4.3 < q2 < 8.68 GeV2/ c 4
20
5200
5400
+
60
LHCb
16 < q2 < 19 GeV2/ c 4
40
20
20
5600
0
m(K π−µ+µ−) [MeV/c2]
+
5200
2
Fit of Nsig in q bins
Use B 0 → J/ψ K ∗0 as normalisation channel
SM prediction [C. Bobeth et al. JHEP 07 (2011) 067]
Data somewhat low but large theory uncertainties due to FF
C. Langenbruch (Warwick), Moriond EW 2015
5600
m(K π−µ+µ−) [MeV/c2]
q 2 [GeV2/ c 4]
[JHEP 08 (2013) 131]
0
LHCb
40
0
5600
LHCb
5
60
m(K π−µ+µ−) [MeV/c2]
60
20
Candidates / ( 10 MeV/c 2 )
0.1 < q2 < 2 GeV2/ c 4
40
60
Candidates / ( 10 MeV/c 2 )
LHCb
Candidates / ( 10 MeV/c 2 )
60
dB /dq 2 [10-7 × c 4 GeV-2]
Candidates / ( 10 MeV/c 2 )
B → K µ µ differential decay rate
Rare decays from LHCb
5400
5600
m(K π−µ+µ−) [MeV/c2]
+
Backup
40 / 28
∗0 + −
0
1
Theory
LHCb
Binned
AFB
FL
B → K µ µ angular observables I
LHCb
0.8
1
Theory
LHCb
Binned
LHCb
0.5
0.6
0
0.4
-0.5
0.2
0
0
5
15
-1
0
20
q 2 [GeV2/ c 4]
LHCb
10
0.4
0.2
0.2
0
0
-0.2
-0.2
-0.4
-0.4
5
5
15
20
q 2 [GeV2/ c 4]
LHCb
0.4
0
10
Binned
A9
S3
Theory
LHCb
10
15
20
q 2 [GeV2/ c 4]
0
LHCb
5
10
Results [JHEP 08 (2013) 131] in good agreement with
SM prediction [C. Bobeth et al. JHEP 07 (2011) 067]
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
15
20
q 2 [GeV2/ c 4]
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41 / 28
The Kπ S-Wave contribution
Can have sizeable contribution with Kπ system in spin 0 configuration
Systematic in previous analysis, Can significantly bias observables for
larger statistics [T. Blake et al.]
Angular distribution [J. Matias], [D. Becirevic et al.]
1
Γfull
1
d3 ΓK ∗0
d3 Γfull
=
(1 − FS )
d cos θ` d cos θK dφ
ΓK ∗0 d cos θ` d cos θK dφ
3
FS sin2 θ` + AS1 sin2 θ` cos θK
+
16π
+ AS2 sin 2θ` sin θK cos φ + AS3 sin θ` sin θK cos φ
+ AS4 sin θ` sin θK sin φ + AS5 sin 2θ` sin θK sin φ
6 additional observables, challenging
Separate analysis to determine dB(B 0 → K ∗0 µ+ µ− )/dq 2 and the
S-wave fraction using fit to mKπµµ , mKπ and cos θK
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
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+ + −
+
0 + −
0
u(d)
t̄
b̄
s̄
W+
Z 0, γ
µ−
µ+
B + → K + µ+ µ−
500
(a) 1.1 < q2 < 6.0 GeV2/ c4
400
LHCb
300
200
100
0
5200
5400
5600
m(K +µ+µ−) [MeV/ c2]
Candidates / ( 10 MeV/c2 )
u(d)
Candidates / ( 10 MeV/c2 )
Angular analysis of B → K µ µ and B → KS µ µ
B 0 → KS0 µ+ µ−
25
(c) 1.1 < q2 < 6.0 GeV2/ c4
20
LHCb
15
10
5
0
5200
5400
5600
m(K 0S µ+µ−) [MeV/ c2]
[JHEP 05 (2014) 082]
NB + →K + µ+ µ− = 4746 ± 81 and NB 0 →KS0 µ+ µ− = 176 ± 17 in 3 fb−1
Experimental challenge: KS0 reconstruction
Differential decay rate for B + → K + µ+ µ−
3
1
1 dΓ(B + → K + µ+ µ− )
= (1 − FH )(1 − cos2 θ` ) + FH + AFB cos θ`
Γ
d cos θ`
4
2
1 dΓ(B 0 → KS0 µ+ µ− )
3
= (1 − FH )(1 − | cos θ` |2 ) + FH
Γ
d| cos θ` |
2
Flat parameter FH sensitive to (Pseudo)scalar contributions, small in SM
Forward backward asymmetry AFB zero in SM
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
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43 / 28
+ + −
+
0 + −
0
0.5
A FB
FH
Angular analysis of B → K µ µ and B → KS µ µ
LHCb
0.4
B + → K + µ+ µ−
0.2
LHCb
B + → K + µ+ µ−
0.1
0.3
0
0.2
-0.1
0.1
0
0
5
10
15
20
-0.2
0
5
FH
q2 [GeV2/ c4]
1.5
15
20
q2 [GeV2/ c4]
LHCb
B 0 → KS0 µ+ µ−
1
0.5
0
0
10
5
10
15
2D fit in cos θ` and m(Kµ+ µ− )
[JHEP 05 (2014) 082] in good
agreement with SM prediction
20
q2 [GeV2/ c4]
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
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+ −
Number of signal events in full 3 fb−1 data sample
Nsig
dB/dq2 [10-8 × c4/GeV2]
B + → K ∗+ µ+ µ−
162 ± 16
Differential branching fractions
LCSR
Lattice
Data
LCSR
B+→ K +µ +µ −
LHCb
4
3
2
1
0
B 0 → K ∗0 µ+ µ−
2361 ± 56
Normalise with respect to B 0 → J/ψ KS0 (K ∗0 ) and B + → J/ψ K + (K ∗+ )
5
0
B + → K + µ+ µ
4746 ± 81
5
10
15
20
Lattice
Data
B0→ K 0µ +µ −
LHCb
5
4
3
2
1
0
0
q2 [GeV2/c4]
5
10
15
20
dB/dq2 [10-8 × c4/GeV2]
B 0 → KS0 µ+ µ−
176 ± 17
dB/dq2 [10-8 × c4/GeV2]
B → Kµ µ branching fraction measurement
LCSR
20
Lattice
Data
B+→ K *+µ +µ −
LHCb
15
10
5
0
0
q2 [GeV2/c4]
5
10
15
20
q2 [GeV2/c4]
[JHEP 06 (2014) 133]
Compatible with but lower than SM predictions
Light cone sum rules (LCSR): [PRD 71 (2005) 014029], [JHEP 09 (2010) 089],
Lattice: [PRD 89 (2014) 094501], [PRD 88 (2013) 054509]
Measurement of dB(B 0 → K ∗0 µ+ µ− )/dq 2 with 3 fb−1 accounting for
S-wave in preparation
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
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(∗) + −
B → K µ µ isospin
LHCb
AI
SM prediction for AI is O(1%)
AI
B → K µ +µ −
1
LHCb
0.5
0.5
0
0
-0.5
-0.5
-1
0
5
10
15
20
-1
0
B(B + →K (∗)+ µ+ µ− )
B → K *µ +µ −
5
10
q2 [GeV2/c4]
15
Results with 3 fb−1 consistent with SM
p-value for deviation of AI (B → Kµµ) from 0 is 11% (1.5σ)
20
q2 [GeV2/c4]
Tensions seen in the 1 fb−1 analysis reduced due to
1. Updated reco./selection 2. Stat. approach 3. Isospin symmetry in J/ψ modes
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
[JHEP 06 (2014) 133]
+
τ
B(B 0 →K (∗)0 µ+ µ− )+ τ 0
+
Isospin asymmetry AI =
1
τ
B(B 0 →K (∗)0 µ+ µ− )− τ 0 B(B + →K (∗)+ µ+ µ− )
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+
46 / 28
+ + − + −
+ + −
+
B → K π π µ µ and B → φK µ µ
Candidates / (10 MeV/c2)
50
1.00 < q2 < 6.00
LHCb
40
30
20
10
0
5200
5300
5400
5500
m(K +π +π -µ +µ -) [MeV/c2]
B + → φK + µ+ µ−
Candidates / (10 MeV/c2)
B + → K + π + π − µ+ µ −
60
16
14
(a)
LHCb
B+→ φ K +µ +µ -
12
10
8
6
4
2
0
5200
5300
5400
5500
5600
m(φ K +µ +µ -) [MeV/ c2]
[JHEP 10 (2014) 064]
First observation of these modes with
+6.0
+
+ + −
Nsig (B + → K + π + π − µ+ µ− ) = 367+24
−23 and Nsig (B → φK µ µ ) = 25.2−5.3
Normalise to B + → ψ(2S)(→ J/ψ π + π − )K + and B + → J/ψ φK +
Determine branching fractions
−7
B(B + → K + π + π − µ+ µ− ) = 4.36 +0.29
−0.27 (stat) ± 0.20 (syst) ± 0.18 (norm) × 10
−7
B(B + → φK + µ+ µ− ) = 0.82 +0.19
−0.17 (stat) ± 0.04 (syst) ± 0.27 (norm) × 10
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
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+ + − + −
+
8
LHCb
7
6
5
4
3
2
1
0
0
5
10
15
q2 [GeV2/ c4]
Candidates / (35 MeV/c2)
dB/dq2 (×10-8 GeV-2c4)
B → K π π µ µ cont.
60
(a)
LHCb
B+→ K +π +π -µ +µ -
50
40
30
20
10
0
1000
1500
2000
2500
m(K +π +π -) [MeV/ c2]
[JHEP 10 (2014) 064]
Performed measurement of dB(B + → K + π + π − µ+ µ− )/dq 2
Significant contribution from B + → K1+ (1270)µ+ µ− expected
Low statistics → no attempt to resolve contributions to K + π + π − final state
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
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250
(a)
200
150
100
50
0
Events / ( 10.6 MeV/c2 )
LHCb
5200
5400
300Direct
250
200
150
B − → K − µ+ µ− prelim.
250
LHCb
(b)
200
150
100
50
0
5600
mK+µ+µ- (MeV/c2)
5200
5400
5600
mK-µ+µ- (MeV/c2)
[JHEP 09 (2014) 177]
300
CP-Asymmetry LHCb
ACP (c)
LHCb (d)
Γ(B̄ → K̄ (∗) µ+ µ−250
) − Γ(B → K (∗) µ+ µ− )
ACP =
Γ(B̄ → K̄ (∗) µ+ µ−200
) + Γ(B → K (∗) µ+ µ− )
ACP tiny O(10−3 ) in the SM
100
Events / ( 10.6 MeV/c2 )
B + → K + µ+ µ− prelim.
Events / ( 10.6 MeV/c2 )
Events / ( 10.6 MeV/c2 )
CP-asymmetry ACP
150
100
Correct for detection and production asymmetry using B → J/ψ K (∗)
50
(∗)
AK
raw
0
5200
µµ
50
(∗)
= ACP + Adet + κAprod , ACP = AK
raw
5400
5600
C. Langenbruch (Warwick), Moriond EW 2015
0
2
5200
µµ
J/ψ K (∗)
− Araw
5400
Rare decays from LHCb
5600
2
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0.2
ACP (B + → K + µ+ µ− ) prelim.
0.1
0
-0.1
-0.2
-0.3
-0.4
-0.5
0
LHCb
5
10
15
20
0.2
0.15
0.1
0.05
0
-0.05
-0.1
-0.15
-0.2
-0.25
-0.3
0
ACP
ACP
CP-asymmetry ACP cont.
ACP (B 0 → K ∗0 µ+ µ− ) prelim.
LHCb
5
q2 [GeV2/c4]
10
15
q2 [GeV2/c4]
[JHEP 09 (2014) 177]
Measured ACP in good agreement with SM prediction
ACP (B + → K + µ+ µ− ) = 0.012 ± 0.017(stat.) ± 0.001(syst.)
ACP (B 0 → K ∗0 µ+ µ− ) = −0.035 ± 0.024(stat.) ± 0.003(syst.)
Most precise measurement
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
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+ + −
+
RK =
= 1 ± O(10−3 ) in the SM
Sensitive to new (pseudo)scalar operators
B + → K + µ+ µ −
25
q2 [GeV2/ c4]
B(B + →K + µ+ µ− )
B(B + →K + e+ e− )
LHCb (a)
20
ψ(2S)K +
15
J/ψK +
10
4
10
3
q2 [GeV2/ c4]
Test of lepton universality in B → K ` `
B + → K + e+ e−
25
103
LHCb (b)
20
ψ(2S)K +
15
102
J/ψK +
10
102
10
5
10
5
1
0
10
radiative tails
0
4800
5000
radiative tails
5200
5400
m(K +µ +µ −)
5600
4800
5000
5200
5400
m(K +e+e−)
[MeV/c2]
5600
[MeV/c2]
[arxiv:1406.6482]
+
+ + −
Experimental challenges for B → K e e
1. Trigger 2. Bremsstrahlung
Use double
N ratio to cancel
N systematic
uncertainties
K + e+ e−
J/ψ (e+ e− )K +
J/ψ (µ+ µ− )K +
K + µ+ µ−
RK = N + + −
N
+ + −
+ −
+
+ −
+
K
e
e
J/ψ (µ
C. Langenbruch (Warwick), Moriond EW 2015
µ
)K
K
µ
mode
µ
J/ψ (e
Rare decays from LHCb
e
)K
1
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51 / 28
+
+ + −
B + → J/ψ (→ e+ e− )K +
LHCb
10
(a)
triggered on e
5
0
5000
RK
LHCb
5200
BaBar
5400
5600
m(K +e+e−) [MeV/c2]
LHCb
1.5
1
0.5
10
LHCb
30
(d)
triggered on e
20
10
0
5000
5200
5400
5600
m(K +e+e−) [MeV/c2]
15
20
q2 [GeV2/ c4]
C. Langenbruch (Warwick), Moriond EW 2015
Use theoretically and experimentally
favoured q 2 region ∈ [1, 6] GeV2
RK = 0.745+0.090
−0.074 (stat.) ± 0.036(syst.),
compatible with SM at 2.6σ
Bq2 ∈[1,6] GeV2 (B + → K + e+ e− ) =
+0.06
−7
(1.56+0.19
−0.15 −0.04 ) × 10
SM
5
40
Belle
2
0
0
B + → K + e + e−
[arxiv:1406.6482]
×103
Candidates / ( 40 MeV/ c2 )
Candidates / ( 40 MeV/ c2 )
Test of lepton universality in B → K ` `
Rare decays from LHCb
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The rare decay
Bs0
b̄
+ −
→ φ[→ K K ]µ µ
s
B0
−
+
s
t̄
W+
Z 0, γ
s
φ
s̄
s
B0
φ
t̄
b̄
s̄
W−
µ−
W+
νµ
µ+
µ+
K + K − µ+ µ− final state not
self-tagging → reduced number of
observables: FL , S3,4,7 , A5,6,8,9
m(µ +µ −) [MeV/c2]
µ−
103
4000
3500
3000
102
2500
Signal yield lower due to fs /fd ∼ 1/4
Clean selection due to narrow
φ resonance
10
1500
1000
LHCb
500
Less S-wave pollution than K ∗0 µ+ µ−
C. Langenbruch (Warwick), Moriond EW 2015
2000
5100
5200
5300
Rare decays from LHCb
5400
5500
5600 − 5700
5800
m(K +K µ +µ −) [MeV/c2]
1
Backup
Angular analysis of
53 / 28
Bs0
+ −
→ φµ µ
In total 174 ± 15 signal events in 1 fb−1 → Not enough for full 3D fit
Integrate over 2 of 3 angles and fit one-dimensional distributions
1
3
3
d2 Γ
= (1 − FL )(1 − cos2 θK ) + FL cos2 θK
2
2
dΓ/dq dq d cos θK
4
2
d2 Γ
1
3
3
3
= (1 − FL )(1 + cos2 θ` ) + FL (1 − cos2 θ` ) + A6 cos θ`
2
2
dΓ/dq dq d cos θ`
8
4
4
1
d2 Γ
1
1
1
=
+
S3 cos 2φ +
A9 sin 2φ
dΓ/dq 2 dq 2 dφ
2π 2π
2π
Remaining parameters FL , S3 , A6 , A9
Updated analysis with 3 fb−1 will allow for 3D angular analysis
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
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LHCb
+ −
→ φµ µ
1.5
a)
LHCb
S3
×10-6
0.1
FL
1
b)
LHCb
0.5
1
0.5
0
0
-0.5
0.05
0
5
10
15
-0.5
5
[JHEP 1307 (2013) 084]
A6
q2 [GeV2/c4]
10
1
c)
-1
15
q2 [GeV2/c4]
LHCb
A9
dB(Bs→φ µ +µ −)/dq2 [GeV-2c4]
Observables in
Bs0
d)
0.5
0
0
-0.5
-0.5
5
10
15
q2 [GeV2/c4]
15
q2 [GeV2/c4]
-1
LHCb
5
Angular observables in good agreement with predictions
Differential B low
C. Langenbruch (Warwick), Moriond EW 2015
10
1
0.5
-1
5
Rare decays from LHCb
10
15
q2 [GeV2/c4]
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Formfactors from lattice calculations
FF from LCSR are calculated at low q 2 and extrapolated to high q 2
Recent FF from lattice at high q 2 [R. Horgan et al. PRD 89, 094501 (2014)]
[R. Horgan et al. PRL 112, 212003 (2014)] combine B 0 → K ∗0 µ+ µ− and
Bs0 → φµ+ µ− at high q 2
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
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2
Fit of high q region using lattice FF
Best fit value C9NP = −1.1, Cp0 = +1.1
Deviation from SM driven by the low branching fractions of both
B 0 → K ∗0 µ+ µ− and Bs0 → φµ+ µ− at high q 2
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb
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Prospects for rare decays in 2018 and beyond
C. Langenbruch (Warwick), Moriond EW 2015
Rare decays from LHCb