Studies of hadronic B decays with early LHCb data

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


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


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


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


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


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

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26

7 a

rXiv

:07

05

.11

21

]


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


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


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


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


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


Observations : time dependent γ trees

B+D0πππ & B0D+πππ

BsDsπππ also seen

Six body final states observed !

~35pb-1 ~35pb-

1

BsDs(Φπ)π


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/


Observations : γ loops

MC expectation

s

Raw asymmetries already visible by eye ! work ongoing on proper estimates

Bd

Bs


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:/

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g/


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


Thank youHave fun : find the 4 PV’s !


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


Charmless diagrams


~35pb-1

Studies of hadronic B decays with early LHCb data

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