0 + - decays in a factorization approach Analysis done in - - PowerPoint PPT Presentation

0 decays in a factorization approach
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0 + - decays in a factorization approach Analysis done in - - PowerPoint PPT Presentation

Dalitz plot analysis of D 0 K S 0 + - decays in a factorization approach Analysis done in collaboration with Robert Kamiski (Institute of Nuclear Physics PAS, Krakw, Poland), Jean-Pierre Dedonder and Benoit Loiseau (LPNHE, Paris,


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Analysis done in collaboration with Robert Kamiński

(Institute of Nuclear Physics PAS, Kraków, Poland),

Jean-Pierre Dedonder and Benoit Loiseau

(LPNHE, Paris, France) published recently in Physical Review D 89, 094018 (2014), arXiv: 1403.2971 [hep-ph].

Dalitz plot analysis of D0 KS

0 + -

decays in a factorization approach

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SLIDE 2

Motivation

  • 1. measurements of the D0 -D0 mixing parameters,
  • 2. determination of the Cabibbo- Kobayashi- Maskawa

angle  in the decay amplitude B  D K , D  KS

0 + -,

  • 3. description of the final state interactions between

mesons, in particular in the S-waves,

  • 4. testing theoretical models of meson form factors,
  • 5. understanding properties of the meson resonances and

their interference effects on the Dalitz plot.

Studies of the D0 KS

0 + - reaction are useful in:

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SLIDE 3

Isobar model and its problems

  • 1. Amplitudes in the isobar model are not unitary neither

in three-body decay channels nor in two-body subchannels.

  • 2. It is difficult to distinguish the S-wave amplitude from the

background terms. Their interference is often very strong.

  • 3. Some branching fractions extracted in such analyses could

be unreliable.

  • 4. The isobar model has many free parameters (at least two

fitted parameters for each amplitude component). Recently Belle used 49 fitted parameters and BaBar 43 parameters.

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SLIDE 4

Why unitarity is important?

Unitary model allows for:

  • 1. proper construction of the D-decay amplitudes,
  • 2. partial wave analyses of final states,
  • 3. explanation of structures seen in Dalitz plots,
  • 4. adequate determination of branching fractions and

CP asymmetries for different quasi-two-body decays,

  • 5. extraction of standard model parameters (weak

amplitudes),

  • 6. application not only in analyses of D decays but also in

studies of other reactions.

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SLIDE 5

Towards a unitary approach

  • 1. Construction of unitary three-body strong interaction

amplitudes in a wide range of effective masses is difficult.

  • 2. As a first step we attempt to incorpotate in our model

two-body unitarity into the D-decay amplitudes with final state interactions in the following subchannels: a) K0  S-wave amplitude, b)   S-wave amplitude, c)   P-wave amplitude.

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SLIDE 6

Allowed and suppressed tree transitions

s du c 

Transition

c d u W+ s

 doubly Cabibbo suppressed

A V A V us cd F

s u c d V V G O

 

 ) ( ) ( 2

* 2

D0

u

  -

u

  - Transition

d su c 

c u W+ s

 allowed

d d

d

D0  + K0

d d

 + K0

225 . sin , ,     

C us cd

V V    

C ud cs

V V  cos  

A V A V ud cs F

d u c s V V G O

 

 ) ( ) ( 2

* 1

C= Cabibbo angle

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SLIDE 7

Tree diagrams with internal W lines allowed doubly Cabibbo suppressed

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SLIDE 8

Annihilation decay amplitudes

c s c d d d

d d d

s

u u

u u

D0 D0

u u

K

+ +  -  - K0 W+ W+

Transition Transition

d su c 

s du c 

allowed doubly Cabibbo suppressed

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SLIDE 9

Factorization approach

main part of the effective Hamiltonian:

2 1 *

2 / j j V V G H

ud cs F

 

Quark currents:

, , ,

A V A V A V A V

d s j c u j d u j c s j

   

    ) ( ' ) ( ' ) ( ) (

2 1 2 1

Factorization:

      

   

| | | | | |

2 1 2 1

j D j K D j j K        

 

| ' | | ' |

2 1

j K D j      

 

| ' | | ' |

2 1

j K D j  

   

 p if j   

| |

2   K K p

if j K    | ' |

2   D D p

if D j    

1 |

' |

f - pion decay constant fK - kaon decay constant fD - D decay constant

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SLIDE 10

Types of decay amplitudes

Seven partial wave amplitudes:

  • 1. S-, P- and D- wave amplitudes in the K subsystem,
  • 2. S-, P- and D- wave amplitudes in the + - subsystem,

including in addition the ω  + - P- wave transition . 27 amplitudes for the D0  KS

0 +  - decay:

a) 7 allowed tree amplitudes, b) 6 doubly Cabibbo suppressed tree amplitudes, c) 14 annihilation (W-exchange) amplitudes (7 allowed and 7 doubly Cabibbo suppressed).

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Resonances in decay amplitudes

Channel: wave: name:

 K

S

  • r

  

) 1430 ( , ) 800 (

* *

K K  P

  

) 1680 ( , ) 1410 ( , ) 892 (

* * *

K K K

) 1430 (

* 2

K

D

 K

same list as above but with pion charge +

 

S

  • r

) 1400 ( ), 980 ( , ) 500 ( f f σ f

P

) 782 ( ), 1450 ( ), 770 (    ) 1270 (

2

f D

Very rich resonance spectrum  complexity of final state interactions

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SLIDE 12

 

  

S

K D

) | (| 2 1 |      K K KS

Allowed transitions with

ud csV

V *

1 

S

K

final state interactions S-wave:

) ( ) ( ] ) )( ( [ 2

2 1 2 2 2 2 2 2 2 2 1 1 1

*

  

 

       m F m A m m m m m m m f f a G A

K DK K D F P      

P-wave:

) ( ) ( )) ( 2

2 2 2 2 1 1 1

*

 

    m F m F m m f a G A

π K π DK π D π F S

m eff. masses of

,

S

K

a1 - effective Wilson coefficient

) (

2

*

π DK

m F

  • D to K0

* transition scalar form factor

 

   m

  • eff. mass

Selected formulae of decay amplitudes

) (

2 

 m

F

π K

  • K0

 scalar form factor

) (

2

*

π DK

m A

  • D to K0

* transition vector form factor

) (

2 1 

 m

F

π K

  • K0

 vector form factor

2 2

) (

K π

p p m  

 2 2

) (

K π

p p m  

 2 2

) (

  

π π

p p m

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SLIDE 13

kaon-pion scalar form factor

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SLIDE 14

pion scalar form factor

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SLIDE 15

2 joint fit

2 2 2 2 Br τ D

χ χ χ χ   

Data for:

  • 1. D0  KS

0 +  - decays, A. Poluektov et al. (Belle Coll.),

  • Phys. Rev. D 81, 112002 (2010),
  • 2. -  KS

0  -  decays, D. Epifanov et al. (Belle Coll.),

  • Phys. Lett. B 654, 65 (2008),
  • 3. total branching fraction Br exp = (2.820.19) %.

Number of degrees of freedom: ndf= 6321 + 89 + 1 – 33 free model param.= 6378. Result: 2 = 9451 which gives 2/ ndf = 1.48.

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SLIDE 16

Dalitz plot density distribution for the D0 KS

0 + - decay

2

) (

 

 π K

p p s

S

2

) (

 

 π K

p p s

S

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SLIDE 17

Comparison of the KS

0 - effective mass

squared distributions with the Belle data

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SLIDE 18

Comparison of the KS

0 + and + - effective

mass squared distributions with the Belle data KS

0 +

 +  -

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SLIDE 19

Comparison with the Belle data on the  -  KS

0  -  decay

mK (GeV)

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SLIDE 20

Branching fractions

[KS

0  - ]S + 25.0  3.6 8.2  0.1 7.9  0.1

KS

0 [ - + ]S 16.9  1.3 14.7  0.2 2.9  0.1

[KS

0  - ]P + 62.7  4.5 24.7  5.7 8.7  3.0

KS

0 [ - + ]P 22.0  1.6 4.4  0.1 6.7  0.04

Channel Br (%) Br (tree) Annihil. low. limit Br (KS

0) = (21.2  0.5) %

Br (K*(892)+-) = (62.9  0.8) %

Exp.

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SLIDE 21

Summary

  • 1. The D0  KS

0 + - decays are analysed using the factorization

approximation.

  • 2. The annihilation (via W-echange) amplitudes are added to the

weak-decay tree amplitudes.

  • 1. The strong interactions between kaon-pion and pion-pion pairs in

the S-, P- states are described in terms of the corresponding form

  • factors. For D-waves we use relativistic Breit-Wigner formulae.
  • 2. The kaon-pion and pion-pion scalar form factors are constrained

using unitarity, analyticity and chiral symmetry and by the present Dalitz plot analysis.

  • 5. A good agreement with the Belle and BABAR Dalitz plot density

distributions and with the -  KS

0 -  decay data is achieved.

  • 6. The lower-limit values of the branching fractions of the annihilation

amplitudes are significant.

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SLIDE 22
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SLIDE 23
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SLIDE 24
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SLIDE 25

Lower limit of annihilation amplitudes 

  

10 1 i i i

M M M A T ;

i i

Ti – tree ampl. Ai – annihilation ampl.

e ampl. fitted ;

i

  • i

ρ i i i i

M M M c M c ds ds Br d   

  2 2 2

| | |

2 . 2 2 2

| | ; | |

i ann i i tree i

A c ds ds Br d T c ds ds Br d  

   

i i ρ i i

T M e A  

Lower limit of the annihilation branching fraction:

| | | | 2

. i i tree i i low ann i

T M ds ds Br Br Br



 

  

 = phase of the KS

0  amplitude

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SLIDE 26

Transition matrix elements (1)

Two mesons form a resonance R=h2h3

      ) ( | | ) ( ) ( ) ( | | ) ( ) (

3 2 23 3 3 2 2

3 2

D h Rh D

p D j p p R s G p D j p h p h

Example:

) ( ) ( ) ( ) (

3 2 1

p p K p p D

D  

  

  

 

*

) 892 ( K K R

 

,

2 2 A V D

c s j m p p p s p p p p

       ) ( ,

1 2 3 2 23 3 2 1 

terms

  • ther

3

       ) ( 2 ) ( | | ) (

2 1 2 1 * 3 2

* *

π DK μ D K D

m A p p p ε m i p D j p p R ) (

2

*

m ADK

Vertex function:

) ( 1 ) ( ) (

23 1 3 2 23

* * *

s F f m p p s G

K K K K K

  

  

 

*

K

polarization

) ( 23

1

s F K

  • kaon-pion transition vector form factor

D to K* transition form factor

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SLIDE 27

Transition matrix elements (2)

      | ' | ) ( ) ( ) ( | ' | ) ( ) ( ) (

3 2 1 1 23 3 3 2 2 1 1

3 2

j p p R p h s G j p h p h p h

h Rh

Example:

 

    

1

, f R K h

 

,

A V D

d s j p p s p p p p

      ) ( ' ,

2 3 2 23 3 2 1

 

     

2 2 23 2 3 2 1

| ' | ) ( ) (

D f K D D K

m F p p s m i j p p f p K

 

) (

2 D f K

m F

  • kaon to f0 transition form factor (complex number)

2nd term

) ( ) (

23 2 23

s F s G f

   

   

 ) ( 23 s F

 

  • pion scalar form factor, 2 - constant
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SLIDE 28

Selected formulae of decay amplitudes (1)

 

  

S

K D

) | (| 2 1 |     K K KS

Allowed transitions with

ud csV

V *

1 

S

K

final state interactions S-wave:

) ( ) ( ] ) )( ( [ 2

2 1 2 2 2 2 2 2 2 2 1 1 1

*

  

 

       m F m A m m m m m m m f f a G A

K DK K D F P      

P-wave:

) ( ) ( )) ( 2

2 2 2 2 1 1 1

*

 

    m F m F m m f a G A

K DK D F S    

D- wave:

* 2 * 2 * 2 * 2 * 2

2 2 2 2 2 1 1 1

) , ( ) ( 2

K K K K K DK F D

im m m m m D G m F f a G A

S

     

     

) (

2

* 2

 m

F DK

  • combination of D to

) 1430 (

* 2 

K transition form factors

* 2 S

K K

G

) , (

2 2   m

m D

  • coupling constant,

= D-wave angular distribution function

m eff. masses of

,

S

K

a1 - effective Wilson coefficient

) (

2

*

m F DK 

  • D to K0

* transition scalar form factor

 

   m

  • eff. mass
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SLIDE 29

Selected formulae of decay amplitudes (2)

S-wave:

) ( ) ( ) ( 2

2 1 2 2 2 2 1 2

m F m A m m f f a G An

D K D F P

 

  

 

   

P-wave:

) ( ) ( ) ( 2

2 2 2 2 2 2 1 2

m F m F m m f a G An

D f K K D F S

 

   

 

D-wave: ) ( ) , ( ) ( 2

2 2 2 2 2 2 2 1 2

2 2 2 2 2

m im m m m m D G m F f a G An

f f f f Df D F D

    

 

) (

2

2 m

F Df

  • combination of D to

) 1270 (

2

f transition form factors ) , (

2 2 m

m D

  • coupling constant,
  • D-wave angular distribution function

 m

effective mass

 

Annihilation ( W-exchange) transitions with

 

final state interactions

) (

2 D f K

m F

a2 - effective Wilson coefficient

  • K0 to f0 scalar transition form factor

) (

2 D K

m A

  •  toK0 transition form factor



2

f

G

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SLIDE 30
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SLIDE 31

Experimental data on D0 KS

0 + - decay

a) A. Poluektov et al. (Belle Coll.), Phys. Rev. D 81, 112002 b) P. del Amo Sanchez et al. (BaBar Coll.),

  • Phys. Rev. Lett. 105 (2010) 081803

2

) (

 

 

p p s

S

K 2

) (

 

 

p p s

S

K 2

) (

  

 

p p s