Hadronic B decays @ LHCb - Kruger20102010-12-05 1
Studies of hadronic B decays with early LHCb data
Aurélien MARTENS (LAL – Univ. Paris Sud 11 – Orsay)
On behalf of the LHCb Collaboration
Hadronic B decays @ LHCb - Kruger20102010-12-05 2
γ and the current status of the CKM matrix
CK
Mfitt
er
Gro
up (
J. C
harl
es
et
al.),
EPJC
41
, 1
-13
1(2
00
5),
Bona e
t al. (
UTfit
Colla
bora
tion),
JH
EP 0
50
7 0
28
(20
05
)
Loops
Trees
Loop constraints are more precise than tree
ones.
Good agreement with some small tension
Direct measurements :
CKMfitter : γ = (71 ± 23)°
UTfit : γ = (78 ± 12)°
Full fit :
CKMfitter : γ = (67.2 ± 3.9)°
UTfit : γ = (65.6 ± 3.3)°
Interest in more precise direct measurements
Hadronic B decays @ LHCb - Kruger20102010-12-05 3
Introduction : γ extraction at LHCbo Current direct determination of γ is mainly dominated by Dalitz
measurements in BDK, DKshh
o There are two direct ways to access the CKM angle γ In tree diagrams : B DX decays
Time integrated Time dependent
In loop diagrams : B hh or hhh charmless decays Assumes U-spin to extract γ
All of these accessible with unprecedented precision at LHCb
o Precise measurements of direct, mixing induced and interferences induced CPV
o Measurements within Standard Model channels and new physics polluted ones uncover new physics contributions in loops
by comparing it with trees By comparing with global fit
Roadm
ap f
or
sele
cted k
ey m
easu
rem
ents
of
LHC
b, arχ
iv:
09
12
.41
79
v2
Hadronic B decays @ LHCb - Kruger20102010-12-05 4
Time integrated γ from treeso An ideal Standard Model candle
Tree diagrams no contribution from new physics in B decays Neglect D mixing : dominant bias but still negligible (~1°) Neglect CPV in D decays : negligible contribution Absolute relative theoretical uncertainty (EW corrections) : Δγ/γ ~ 10-6
ADS
[P
RL 7
8 3
257(1
997);
PR
D 6
3 0
36005(2
001)]
, GLW
[P
LB
253 4
83(1
991);
PLB
265 1
72(1
991)]
, GGSZ
[P
RD
68
054018(2
003)]
bu and bc transitions interfere
Colour AllowedCabibbo Favoured
e-iγ
Colour Suppressed
D0’s reco. in the same final state :
CP eigenstate KK, ππ [GLW]2 bodies & al. Kπ, Kππ0, K3π [ADS]Dalitz Kshh [GGSZ]
BR rB
B+D0K+ (3.7 ± 0.3) 10-4 0.1
B0D0K*0 (4.2 ± 0.6) 10-5
~0.3
ADS : CLEOc constraints on D decay
Extentions : D0Kπ Dalitz analysis with higher statisticsBsDΦ integrated-untagged measurment
Hadronic B decays @ LHCb - Kruger20102010-12-05 5
Time dependent γ from treeso An additional information from time dependent measurements
Measure γ+ΦM need an external model independent measurement of the mixing phase
Benefits from non vanishing lifetime differences [ for Bs, for Bd]
Ale
ksan &
al. [
ZPC
54
65
3(1
99
2)]
, D
unie
tz &
al. [
PR
D 3
7
31
86
(19
88
) ;
39
35
15
E(1
98
9)]
, D
unie
tz [
PLB
42
7
17
9(1
99
8)]
MIXINGe-iγ
Simultaneous U-spin based extraction :resolve 8-fold ambiguities (degenerated at low statistics) in BdD+π-
BR x [R]angl
e
BsDs+K- (3.0 ± 0.7)
10-4
0.4 γ+Φs
BdD+π- (2.7 ± 0.1) 10-3
0.02 γ+2β
Hadronic B decays @ LHCb - Kruger20102010-12-05 6
γ from loopso Inclusive Bhh or hhh analyses
bu involved in many (2,3)-bodies charmless B decays Less particles in the final state more efficient trigger and reconstruction
Examples of contributing and
interfering diagrams
(more in backup)
BR 10-610-5
Upper limits 10-6
Fleis
cher
[PLB
45
9(1
99
9)
30
6 a
rXiv
:99
03
45
6, EPJ
C5
2(2
00
7)
26
7 a
rXiv
:07
05
.11
21
]
Hadronic B decays @ LHCb - Kruger20102010-12-05 7
LHCb in a nutshellThe Challenge: precise rare decays and time-dependent CP
asymmetries in a high background environment.
Needs excellent vertexing, p reconstruction, particle-ID
VErtexLOcator,
PileUp
Trigger Tracker
Tracking Stations
RICHES:PID: K, separation
Muon System
Calorimeters
The L
HC
b D
ete
ctor
at
the L
HC
[JIN
ST 3
S0
80
05
]
See Plenary by O. Steimkampf
Hadronic B decays @ LHCb - Kruger20102010-12-05 8
Trigger
HLT2 :Inclusive Topological Trigger :- Build a B using 2,3,4 tracks- Compensate for missing pT
HLT1 :- Build a ‘good’ track from any L0 Recover some efficiency for hadronic triggers
The bottleneck :- Bandwidth and rate limitations- Already high (3.6 GeV) ET hadronic triggers
Hadronic B decays @ LHCb - Kruger20102010-12-05 9
Analysis requirements : PID
Hadronic B decays intensive use of PID in any analysis
Performance is close to MC expectations
Lifetime and Tagging performance studies also under progress
See talk by A. Contu
Hadronic B decays @ LHCb - Kruger20102010-12-05 10
Observations : time integrated γ trees
Clean hadronic B signals observed
reasonably in agreement with
expectations
First observation of pure colour suppressed hadronic B decays in a
hadron collider (?)
Wait for full 2010 run reprocessing to
observe BDK with DKK
Expect 15 to 50 BsD0K*0 in the full 2010 reprocessing
BD(Kπ)ρ74 ± 11
BD(Kπ)K444 ± 30
~35pb-
1
BD(KK)π1035 ± 54
~35pb-
1
BD(Kπ)ρ0
74 ± 11
~35pb-
1
Hadronic B decays @ LHCb - Kruger20102010-12-05 11
Prospects : time integrated γ trees
Arχ
iv:1
00
7.0
50
4, PR
D 8
1, 0
31
10
5(R
)(2
01
0)
+ p
relim
inary
resu
lts
@ C
KM
20
10
DK ACP+
BaBar 0.25 ± 0.06 ± 0.02
CDF 0.39 ± 0.17 ± 0.04
DK AADS
Belle −0.39 ± 0.26 +0.06 −0.04
CDF −0.63 ± 0.40 ± 0.23Current status on the
measurement of asymmetries
LHCb 1fb-1 @ √s=7TeV :
Competitive measurements with current dominating
measurements
possible first results from LHCb @ Winter 2011 conferences :- ACP+ and RCP+ competing with CDF- ratios of BR(BDK)/BR(BDπ)- First observation of BsD0K*0 and BR(BsD0K*0)/BR(BdD0ρ0)
~15° LHCb combined sensitivity on time integrated γ in 2011
ADS
Hadronic B decays @ LHCb - Kruger20102010-12-05 12
Observations : time dependent γ trees
B+D0πππ & B0D+πππ
BsDsπππ also seen
Six body final states observed !
~35pb-1 ~35pb-
1
BsDs(Φπ)π
Hadronic B decays @ LHCb - Kruger20102010-12-05 13
Prospects : time dependent γ trees
B factories legacy
possible first results from LHCb @ Winter 2011 conferences :- Measurements of ratio of BR(B0DK)/BR(B0Dπ)- Upper limits on BsD(K,π)- First observations of D(s)(Kππ) and best measurements of D(s) (πππ) - fd/fs from N(B0DK)/N(BsDsπ)
~15° statistical sensitivity on time dependent γ in 2011
Fleis
cher,
Serr
a, Tunin
g [
Arχ
iv:1
00
4.3
98
2v3
]htt
p:/
/ww
w.s
lac.
stanfo
rd.e
du/x
org
/hfa
g/
Hadronic B decays @ LHCb - Kruger20102010-12-05 14
Observations : γ loops
MC expectation
s
Raw asymmetries already visible by eye ! work ongoing on proper estimates
Bd
Bs
Hadronic B decays @ LHCb - Kruger20102010-12-05 15
Prospects : γ loops
possible first results from LHCb @ Moriond 2011 :- Measurement of BR(BsKπ)/BR(BdKπ)- ACP measurements competitive with CDF results
~15° sensitivity on γ loops for LHCb by fall 2011
B0KπPDG10Aver.
−0.098 ± 0.013
CDF −0.086 ± 0.023 ± 0.009
BsKπ
CDF 0.39 ± 0.15 ± 0.08
CD
F, [
N P
B (
Pro
c. S
uppl.)
17
0 (
20
07
) 3
9–4
5]
htt
p:/
/ww
w.s
lac.
stanfo
rd.e
du/x
org
/hfa
g/
Hadronic B decays @ LHCb - Kruger20102010-12-05 16
Summaryo LHCb is performing well and is already able to observe hadronic B
decays 10-5 and 10-6 hadronic decays are observed or about to be so
Discoveries of new expected Bs decay modes hopefully for Winter conf.
Raw asymmetries observed in some channels Hopefully calibrated by Winter conf. to produce first CPV results
o Wait for even more exciting data taking periods in 2011 γ sensitivity is going to be of the order of 15° in loops AND trees γ sensitivity of 15° both in time independent AND time dependent trees
Competitive with existing measurements
LHCb will be competitive with CDF results
LHCb will improve our knowledge on γ by the end of 2011
Hadronic B decays @ LHCb - Kruger20102010-12-05 17
Thank youHave fun : find the 4 PV’s !
Hadronic B decays @ LHCb - Kruger20102010-12-05 18
Additional requirements : Lifetime & tagging
o Lifetime and Tagging are key ingredients for time dependent and Bhh
Lifetime resolution of 77fs (worse than expected)Recent improvements obtained
Tagging performance studies under progress
Hadronic B decays @ LHCb - Kruger20102010-12-05 19
Charmless diagrams
Hadronic B decays @ LHCb - Kruger20102010-12-05 20
~35pb-1
Top Related