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# Experimental review of CKM sides at B factories - PowerPoint PPT Presentation

Experimental review of CKM sides at B factories. A. Oyanguren (IFIC, UV-CSIC) (BaBar Collaboration). DISCRETE 2008. V td. V ub. V cb. Introduction & outline. The Cabibbo-Kobayashi-Maskawa matrix:. V ud V us V ub V cd V cs V cb V td V ts V tb. V CKM =.

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CKM sides at B factories

A. Oyanguren (IFIC, UV-CSIC)

(BaBar Collaboration)

DISCRETE 2008

Vtd

Vub

Vcb

VudVusVub

VcdVcsVcb

VtdVtsVtb

VCKM=

VudVub* + VcdVcb* + VtdVtb* = 0

 From Bd and Bs mixing

 From exclusive sl decays:

|Vcb|: BD*l, BDl;

|Vub|: Bl, Bl

B(‘)l, Bl…

A

~|Vtd/Vts|

~|Vub/Vcb|

From inclusive BXcl (|Vcb|)

and BXul (|Vub|) decays

(1,0)

(0,0)

1

2

DISCRETE 2008

A. Oyanguren

 1200 fb-1recorded !

Analysis techniques:

-

-

K+

D0

Untagged

(High efficiency)

(High purity)

lepton

D0

Signal side

Signal side

lepton

lepton

B0

B0

B0

-

B0

B0

B0

D*

+

+

(4S)

(4S)

X

X

X

(4S)

Tag side

Tag side

3

DISCRETE 2008

A. Oyanguren

|Vcb| from exclusive sl decays

From B D   (BR ~2% , suppressed at high q2)

From B D*   (BR ~ 5%)

Vcb

q2

Kinematic function

Form factor

(shape & normalization)

Theory:

G(1)*=1.074  0.018  0.016

B  DD2

F(1)*=0.921  0.013  0.020

B D* D*2, R1(1), R2(1)

Measuring the decay rate and ff shape  |Vcb|

* M.Okamoto et al NPPS 140, 461(2005))

* C. Bernard et al arXiv:0808.2519 [hep-lat]

4

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|Vcb| from BD

• Select the lepton,

• reconstruct the D0 into several channels

 Reconstruct the other B into hadrons (Btag)

 Reconstruct the missing mass:

m2miss = (p(4s)– pBtag-pD-pl)2

m2miss = 0.04 GeV2

 Fit the signal yield into 10 w bins (ML fit)

417fb-1

2 = 1.20 0.09  0.04

 2 fit to extract D2 and G(1)|Vcb|

G(1) |Vcb| = (43.0 1.9 0.4) 10-3

B (B0D+-)= (2.170.06 0.07)%

arXiv:0807.4978

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|Vcb| from BD*

• Reconstruct the semileptonic decay

• D0K, K3 + soft  (to make D*)

• + lepton

• The decay rate depends

• on w, , V , 

• Constraint pB  pinclusive = pall–D*

 Define the angle between the B

and the D* candidate

 4D 2 fit to extract D*2, R1, R2 and F(1)|Vcb|

w = 0.025

cosv= 0.052

 Fit the signal yield

140 fb-1

= 6.47

cos=0.047

preliminary

F(1) |Vcb| = (34.4 0.2 1.0) 10-3

R1= 1.495 0.050  0.062

2 = 1.293 0.045  0.029

R2= 0.844 0.034  0.019

B (B0D*+-) = (4.420.03 0.25)%

DISCRETE 2008

Global fit to BD and BD*

207fb-1

• Reconstruct D0 and D+ candidates

• (D0K-+, D+K-++)

B(B-D*0-)= (5.370.02 0.21)%

D*2 = 1.21 0.02  0.07

• Use p*, p*D and cosB-D to separate

• BD and BD* decays

F(1) |Vcb| = (35.7 0.2 1.2) 10-3

B (B-D0-)= (2.360.03 0.12)%

• 3D 2 fit to the yields to extract the

• form factor slopes, D and D* and BD

• and BD* BRs (R1 and R2 fixed).

D2 = 1.22 0.04  0.07

G1) |Vcb| = (43.8 0.8 2.3) 10-3

D

preliminary

D*

1

1.5

2

1.5

2

-2

-1

0

1

arXiv:0809.0828

7

DISCRETE 2008

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|Vcb| from exclusive sl decays

G(1)|Vcb| = (42.4  1.56) x 10-3

2/dof =1.2/8

usingG(1) =1.074  0.024

|Vcb| = (39.5  1.5exp 0.9latt) x 10-3

Exp: - waiting Belle update

- systematics  tracking eff,

F(1)|Vcb| = (35.41  0.52) x 10-3

2/dof =39/21

using F(1) =0.921  0.024

|Vcb| = (38.4  0.6exp  0.9latt) x 10-3

- systematics  tracking eff, D**

8

BD**l

HQET

PRD77,091503(2008)

605 fb-1

D*

?

D**

D

Ground

states

Narrow

states

• B(B0Xc) > B(B0D)+ B(B0D*)+ B(B0D**)

[10.1  0.4]%

+ [5.16  0.11]%

+ [1-2]%

> [2.17  0.12]%

B0D*0+-

B-D*+--

417 fb-1

B-D+--

B0D0+-

 Belle does not see the D1’,

BaBar does.

arXiv:0808.0528

Theory predicts B(D1*,D2*) >> B(D*0,D1’), Experiments see B(D1*,D2*) <~ B(D0*,D1’)

9

|Vcb| from inclusive sl decays

Operator Product Expansion (OPE):

x

=

Vcb

kineticenergy, spin...

Some inclusive observablesO  depend on the same parameters

BXc

: theleptonenergy, themassdistribution,

(Forinstance:

BXs

: thephotonspectrum)

Measurement of moments:

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MXcand El moments

• One B fully reconstructed into hadrons (Btag)

• Oneleptonfromtheother B (signal)

•  measure E (electrons)

• Rest of particles  measure mx

• Event by event calibration

• Unfolded with SVD algorithm

• < Een> measured as function of p*e cut

• (from 0.4 to 2. GeV/c)

• < Mxn> measured as function of p*l cut

• (from 0.8 to 1.9 GeV/c)

PRD 75, 032001(2007)

210fb-1

140fb-1

e+

arXiv:0707.2670

• < Mxn> for n=1,2,3,4,5,6

• < Een> for n=0,1,2,3,4

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DISCRETE 2008

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W+

S

b

t

• Select high energy photons (E*> 1.4 GeV)

• Off-peak subtraction,

• veto to photons from 0 and 

• Unfolded with SVD algorithm

• < En> measured as function of

• Ecut (from 1.7 to 2.1 GeV)

605fb-1

• < En> for n=1,2

PRD 78, 032016(2008)

12

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|Vcb| from inclusive sl decays

 Using 27 moments from BaBar, 25 moments from Belle and 12 momentsfromotherexperiments(http://www.slac.stanford.edu/xorg/hfag/semi/ichep08/gbl_fits/kinetic/)

|Vcb| =(41.67  0.43fit 0.08 B  0.58th) x 10-3

mb =(4.601  0.034) GeV

2 =(0.440  0.040) GeV2

(Exclusive (BD*):

|Vcb| = (38.4  0.6exp  0.9latt) x 10-3

|Vcb|incl - |Vcb|excl : 2.5

13

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|Vub| from exclusive sl decays

Analysis methods:

 Untagged (high stat., most precise)

(BR ~ 0.01% +

large bc bkg)

p, h, h’, r, w

•  reconstruction from full event

• (p = pbeams - pi)

 Fit E = EB – s /2 and mES = s/4-|p*B|2

to extract the signal yield

206fb-1

• q2= (pB - p )2 in 12 bins  Form factor fit

B (B0-)= (1.460.07 0.08)x10-4

PRL 98, 091801(2007)

14

DISCRETE 2008

|Vub| from exclusive sl decays

Tagged B

pB

(sl tag)

B

pD(*)l

pl

 Reconstruct one B into hadrons (Btag)

• Select the lepton from the other B

• One B decaying into B D(*) (Btag)

• select the  ( rec.  or  into pions)

• Other lepton (-q) from the other B

 Reconstruct the missing mass:

m2miss = (p(4s)– pBtag-p-pl)2

• Define the systems Y=D(*) and X=

• Fit to cos2B in 3 q2 bins

• Extract yields in 3 q2 bins

348fb-1

B0-

B+0

605fb-1

signal

signal

0805.2408 [hep-ex]

B (B0-)= (1.120.18 0.05)x10-4

B (B0-)= (1.540.17 0.09)x10-4

B (B+0)= (0.660.12 0.03)x10-4

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|Vub| from exclusive sl decays

Form factor necessary to extract |Vub| theory

Models depend on q2 region:

(Untagged analysis can

measure the form factor

from data)

B (B0-)= (1.340.06 0.05)x10-4

PRL 98, 091801(2007)

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|Vub| from exclusive sl decays

B  (,,’,) 

Checktheoreticalcalculations

Composition of BXu

348fb-1

605fb-1

signal

sl tag:

0805.2408 [hep-ex]

347fb-1

B (B0-)= (2.800.18 0.16)x10-4

untagged

0808.3524 [hep-ex]

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|Vub| from inclusive sl decays

50 : 1

BX = BXc + BXu

• Theoryneedslowmomentumcutstoextract|Vub| (OPE breaksdown in theShapeFunction (SF) region:

• low mx2 and q2)

• OPE parameteres (mb, 2 ) frommoments in BXc and BXs

• Experimentsneedhighmomentum

• cutstosuppressb  c bkg

Experimental technique:

Measure partial BR

 Tagged (sl or hadronic) or untagged

 Use kinematic variables to suppress as much as possible b  c (keeping reliable theoretical calculations):

El, q2, mX and P+ = EX -|pX|

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• Select regions below charm threshold

• Key: bkg subtraction (off-peak data,

• endpoint, MC… )

• bc bkg constrained by data in the

• low energy region

• One B fully reconstructed

• for the signal side

signal

81fb-1

signal

PR73:012006,2006.

signal

27fb-1

bc (MC)

347fb-1

bkg

bkg

~40-60% acceptance

1.55 GeV

0.66 GeV

signal

8 GeV2

arXiv:0708.3702

PRB601:28(2005)

81fb-1

signal

604fb-1

bkg

Shmax=f(E, q2) = maximum mx squared

(new Belle multivariate analysis  no hard cuts, 90% PS)

PRL95:111801(2005)

|Vub| from inclusive sl decays

• Relating the rate to bs to reduce

• model dependence (LLR method)

 Moments of the full mass spectrum

 OPE fit to extract mb, 2 and .

unfolded

220fb-1

80fb-1

B  Xc

B  Xs 

B  Xu

mx cut =1.67

mb =(4.604  0.250) GeV

arXiv:0801.2985

2 =(0.398  0.240) GeV2

PRL96:221801(2006)

mx cut (GeV/c2)

20

20

|Vub| from inclusive sl decays

OPE based + SF

‣BLNP: HQE with systematic introduction of SF

PRD71:073006 (2005)

‣BLL: phase space in mx-q2 with reduced SF

PRD64:113004 (2001)

‣GGOU: kineticscheme

JHEP 10(2007) 058

‣LNP (LLR): b→s directly related to b→ uν

JHEP 0510:084 ( PLB 486:86 )

No SF introduced (model non-perturbative QCD)

‣DGE: DressedGluonExponentiation

JHEP 0601:097 (2006)

PRD74:03400(4,5,6) (2006)

Vub incl

Vub excl

More data, more SP +

improvementsfromtheoryneeded

|Vub|from =(3.44  0.16)10-3

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Exclusive

b

u,c,t

d/s

 - , / K*

B-

Inclusive

(Sum of

all channels)

Formfactors

u

arXiv:0804.4770

• Select high energy photons

B→ Xsg

• veto to photons from 0 and 

• remove bkg from continuum

 Yield from E = EB – s /2

and mES = s/4-|p*B|2

0.6 < MXd/s < 1.0 GeV

(error from fBsBBs / fBdBBd )

B→ Xdg

NeedSuperB!

1st error exp., 2nd theo.

22

DISCRETE 2008

PRL101:111801,2008

The CKM matrix:

 decays

 Decays (0+0+)

Vud/Vud

~ 0.03%

Vus/Vus

~ 0.4%

Vub/Vub

~ 8%

Vcd/Vcd

~ 5%

Vcs/Vcs

~ 11%

Vcb/Vcb

~ 2%

Needtheoryimprovements

(excl . vs incl. ??)

(Vtd/Vts)/(Vtd/Vts)

~ 3%

Vtb/Vtb

~ 15%

charm sl decays

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HFAG

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HFAG

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