BUBBLE CHAMBER WORK ON NON-DIFFRACTIVE WASI-TWO-BODY REACTIONS

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Submitted on 1 Jan 1973

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BUBBLE CHAMBER WORK ON NON-DIFFRACTIVE WASI-TWO-BODY

REACTIONS

G. Otter

To cite this version:

G. Otter. BUBBLE CHAMBER WORK ON NON-DIFFRACTIVE WASI-TWO-BODY REAC- TIONS. Journal de Physique Colloques, 1973, 34 (C1), pp.C1-298-C1-300. �10.1051/jphyscol:1973138�.

�jpa-00215218�

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G. OTTER

BUBBLE CHAMBER WORK ON NON-DIFFRACTIVE WASI-TWO-BODY REACTIONS

G. OTTER

P h y s i k a l i s c h e s I n s t i t u t , Aachen

A quasi-two-body r e a c t i o n i s completely d e s c r i b e d by t h e s

-

^and t

-

dependence o f a l l i t s ampli- t u d e s , b u t t h i s d e t a i l e d i n f o r m a t i o n i s normally not a v a i l a b l e . I n most well-known p r o c e s s e s only t h e s- and t -dependences of t h e c r o s s - s e c t i o n and of t h e d e n s i t y m a t r i x elements of t h e resonances involved a r e e x p e r i m e n t a l l y known, New r e s u l t s on t h e s -and t-dependences of some r e a c t i o n s a r e reviewed f i r s t , followed by a d i s c u s s i o n of some p a p e r s d e a l i n g w i t h o t h e r s u b j e c t s .

1.- s-DEPENDENCE.

-

The ABCLV-collaboration s t u - d i e d t h e energy dependence of some K-p many-body- r e a c t i o n s a t 6,10 and 16 GeV/c [ I

1 .

The r e a c t i o n s were d i v i d e d i n t o s u b r e a c t i o n s depending upon which p a r t i c l e s go forward o r backward i n t h e cm system.

The method, r e f e r r e d t o a s "binary LPS", i s a gene- r a l i s a t i o n of a method used by Morrison [ 2 ] , t o s t u - dy quasi-two-body r e a c t i o n s . The c r o s s - s e c t i o n s of t h e v a r i o u s s u b r e a c t i o n s were p a r a m e t r i s e d by C plab -n

,

^where n i s e m p i r i c a l l y r e l a t e d t o t h e quantum numbers exchanged between t h e forward and backward going p a r t i c l e s and t h e v a l u e s found a r e very s i m i l a r t o t h e s e o b t a i n e d from quasi-two-body r e a c t i o n s .

The Tel-Aviv-Heidelberg c o l l a b o r a t i o n i n v e s t i g a t e d t h e energy dependence of t h e r e a c t i o n s $p -t K - X + ~ , K ~ P KK+z-p i n t h e i n c i d e n t momentum range 0 . 8 t o 3.0 GeV/c [3]

.

They were e s p e c i a l l y i n t e r e s t e d i n t h e p r o d u c t i o n of t h e systems KEN p

.

Using t h e r e s u l t s of t h i s experiment and some a l r e a d y e x i s t i n g K - ~ 4 K+ N d a t a , a n i s o s p i n a n a l y s i s of KN -t

sgQ .-

- *

~i~~

^N ^and ^KN^-+KsgO N was c a r r i e d out. I n both r e a c t i o n s t h e I c: 0 p a r t i s l a r g e r than t h e ?

=

¹

p a r t . The i n t e r f e r e n c e i n t h e second r e a c t i o n i s compatible with z e r o whereas i t i s very l a r g e and n e g a t i v e i n t h e f i r s t r e a c t i o n ( f i g . 1 ) .

2.- +DEPENDENCE.

-

BNL submitted a paper on a

+ +

s y s t e m a t i c s t u d y of t h e r e a c t i o n s X-p 4 p'p and

CP

pOn a t 6 GeV/c [4]

.

An i s o s p i n a a a l y s i s

Fig.1

-

C r o s s s e c t i o n f o r I

=

0 ( C O), I r: 1 ( C 1 1 and i n t e r f e r e n c e p a r t s f o r KN 4

q N N

^and

KN 4

il*

N. The shaded band corresponds t o maxi- mal int%!?erence.

shows t h a t t h e r e i s no i n t e r f e r e n c e between t h e amplitudes f o r I

=

⁰and I

=

¹ exchange. The I

=

0 p a r t i f w e l l d e s c r i b e d by w-exchange and t h e I

=

1 p a r t i f dominated by 'It-exchange. Using a s i m - p l e model f o r 7i-exchange ( a m o d i f i c a t i o n of t h e Williams model [ 5 ] ) and H a r a r i 's d u a l a b s o r p t i o n model f o r *exchange [ 6 ]

,

a n amplitude a n a l y s i s f o r t h i s p r o c e s s i s c a r r i e d out.

Bouchez and M a l l e t p r e s e n t e d p r e l i m i n a r y r e s u l t s from an amplitude a n a l y s i s of t h e r e a c t i o n

<p+pOn

and P-P a t 3.9 GeV/c [7I

.

The amplitudes and t h e i r r e l a t i v e phases have been determined a s a

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1973138

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BUBBLE CHAMBER WORK ON NON-DIFFRACTIVE QUASI-TWO-BODY REACTIONS C1-299

f u n c t i o n o f t

.

E i s e n b e r g e t a l . i n v e s t i g a t e d t h e quasi-two-body r e a c t i o n x+p -t p ⁰^{a + +} a t 5 GeV/c i n a l a r g e s t a - t i s t i c s e x p e r i m e n t [ 8 ]

.

They found a v e r y s t r o n g f o r w a r d peak i n t h e dV/dt' w i t h a s l o p e o f 22 k 2 G ~ v - ~ (which comes from t h e dominance of %-exchange

i n t h i s p r o c e s s ) , b u t no o t h e r s t r u c t u r e was found i n t h i s d i s t r i b u t i o n . A s t r o n g d i p a t It'

I ⁼

^0.2GeV²

was o b s e r v e d i n t h e h e l i c i t y - f l i p - 1 n a t u r a l p a r i t y exchange p a r t ; i t i s p r o b a b l y due t o A2 exchange.

The r e a c t i o n ~ + n -t U p a t 4 GeV/c was s t u d i e d by t h e Durham-Birmingham-Rutherford c o l l a b o r a t i o n [ 9 ]

.

From t h e d e n s i t y m a t r i x e l e m e n t s t h e y conclu- ded t h a t b o t h B and p-exchange a r e needed. Con- c l u s i o n s o n d e t a i l e d r e s u l t s m y h w e v e r be m c d i f i e d s i n c e no c o r r e c t i o n s were a p p l i e d f o r t h e 30% back- ground under t h e f.0

.

Karshon e t a l .

[ l o ]

i n v e s t i g a t e d t h e r e a c t i o n x++p ^-t ~ + p a t 5 GeV/c which was n o t v e r y w e l l s t u d i e d up t o now. T h e r e a r e i n d i c a t i o n s t h a t dC/dt' h a s a s h o u l d e r a t t '

= -

0.2 G ~ v ~ , and t h a t

00

dC/dt' h a s a d i p h e r e ( i n agreement w i t h a c o r r e s - ponding x-p experiment a t s i m i l a r e n e r g i e s [ i l l ) .

T h i s r e s u l t c a n be e x p l a i n e d by t h e dominance o f W-exchange. The s u p p r e s s i o n o f A2 exchange i s a l s o a p p a r e n t i n a s t u d y

[lo]

o f t h e r e a c t i o n x+p -t BOA++

w i t h a f i v e t i m e s s m a l l e r p r o d u c t i o n c r o s s s e c t i o n t h a n f o r t h e f i n a l s t a t e B + ~

.

However, t h e Roches- t e r g r o u p f i n d s a s t r o n g ( x A 2 B) c o u p l i n g i n t h e r e a c t i o n 7t-n -t 9-A0

,

s t u d i e d i n f d i n t e r a c t i o n s a t 7 GeV/c [ 1 2 ]

.

The T o r o n t o group i n v e s t i g a t e d x+p -t KOA++ and

%+P - ' 7 1 ~ + + a t 5.45 GeV/c [ 1 3 1

.

Both r e a c t i o n s e x h i b i t c r o s s - s e c t i o n s w i t h a s i m i l a r power law ( n

=

1.59

+-

.09 f o r xoA++ and n

=

^1.57

^C-

- 1 5 f o r V A ++). The f i r s t r e a c t i o n i s dominated by p and t h e second by A 2

-

exchange.

The CERN-Birmingham-Brussels-Mons-Saclay-Paris c o l l a b o r a t i o n s t u d i e d s y s t e m a t i c a l l y t h e r e a c t i o n K+p -t K"O A++

8 9 0 from 4.6 t o 1 6 GeV/c [ 1 4 1

.

dT/dt1 h a s a s t r o n g f o r w a r d peak. T h i s and t h e l a r g e v a l u e o f t h e d e n s i t y m a t r i x e l e m e n t

Poo

i n t h e f o r w a r d d i r e c t i o n ( s e e f i g . 2 ) i n d i c & t e dominance o f X-exchange. F i t s t o dC/dt

, Po,

and

P l l

-

^PI-1

( i n e i t h e r t h e J a c k s o n o r h e l i c i t y f r a m e ) g i v e a n e f f e c t i v e R e g g e - t r a j e c t o r y w i t h a n i n t e r c e p t t h a t i s

. . - . .

d FRAME 546 Gem HELICITY FRAME JACKSON FRAME 546 Gem HELICITY FRAME

02 -

0 I I

I I I I I I I I I I I I I I I I I l I I I ! I I I I 002 -

I I I I I

I

I I I I I I I I I I

0.2 -

Q.

0 0 ';--- - - - - - -- ---

z

^'tt

~ - O , ~ - ~ I I I I I I I I I I I I I I I I I ~

^I

I l l

I I

0 0.2 0,4 0.6 008 0 C ,2 064 06 088 1.0

F i g . 2

-

D e n s i t y m a t r i x e l e m e n t s f o r K z g 0 i n ICfp ⁺

Kzi0

^A++

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C 1 -300 G. OTTER

much t o o low ( a

= -

.24

i

.05) and a s l o p e t h a t i s t o o f l a t f o r a T-Regge p o l e .

Two o t h e r s u b m i t t e d p a p e r s s t u d y s i m p l e one-pion- exchange f o r t h e r e a c t i o n s np 4

a-

A++ a t 3GeV/c

[15] and

Gp 45"

A++ a t 5.7 GeV/c [16]

.

^Both

e x p e r i m e n t s found a s t r o n g f o r w a r d peak c o n s i s t e n t w i t h x-exchange. S t a t i s t i c a l t e n s o r s c a l c u l a t e d f o r t h e d o u b l e decay were i n c o n s i s t e n t a i t h t h e pre- d i c t i o n s o f s i m p l e OPE

.

T h i s i n d i c a t e s t h a t absorp- t i o n is needed t o e x p l a i n t h e d a t a .

Backward p r o d u c t i o n o f K I g O by i n c i d e n t K+ me- s o n s was i n v e s t i g a t e d by t h e CERN-Munich-Mons-Brussels c o l l a b o r a t i o n i n t h e 3-5 GeV/c r a n g e [ 1 7 ]

.

^The

c r o s s - s e c t i o n v a r i e s l i k e p lab -n w i t h n

=

3.2

+

^.5,

c o m p a t i b l e w i t h baryon exchange. Combining t h e r e - s u l t s w i t h some o t h e r backward v e c t o r meson produc- t i o n r e a c t i o n s , r e l a t e d by SU(3), t h e e f f e c t i v e F/D r a t i o f o r t h e (B V B ) - c o u p l i n g was found t o

8 8 8 be .07 + * I 5

- . 0 7 '

results were compared w i t h vector-dominance model p r e d i c t i o n s . A l a r g e n e g a t i v e i n t e r f e r e n c e between t h e ^W and P-amplitudes was found t o b e n e c e s s a r y t o o b t a i n agreement w i t h t h e model a t l e a s t f o r

luI 2 0 . 5 GeV 2

.

3.- MISCELLANEOUS.

-

I n t h i s p a r t I would l i k e t o mention two items. T e n n e r e t a l . [ 1 9 1 s u b m i t t e d a p a p e r i n which t h e r e a c t i o n s ~ ' p -' K*' n'p a r e d e s c r i b e d i n terms o f V e n a i a n o a m p l i t u d e s . D a t a a t 1 4 d i f f e r e n t momenta from 2.7 t o 12.7 GeV/c have been compared w i t h t h e model c a l c u l a t i o n and t h e agreement i s q u i t e good.

Another p a p e r makes a comparison of t h e q u a r k mo- d e l w i t h t h e r e a c t i o n s ~ + p d and

p

a t 5 GeV/c [ 2 0 ]

.

The C l a s s A quark model r e l a t i o n s a r e s a t i s f i e d w i t h i n s t a t i s t i c s f o r 7t'p + W A++

( e v e n a t l a r g e momentum t r a n s f e r s ) , b u t t h e r e a r e d e v i a t i o n s from t h e model f o r t h e x + ~ -'

pa++

d a t a . Backward p r o d u c t i o n of P O , w0 and f 0 -mesons was

s t u d i e d by t h e Rutherford-Birmingham-Durham c o l l a - b o r a t i o n [ I S ]

.

I n t h e c a s e of

p

and w

,

t h e

REFERENCES [l

] GGSSLER

(H. ) e t a l . , Aachen-Berlin-CERN-London

Vienna c o l l a b o r a t i o n , p a p e r 8 0

[ 2 ] MORRISON (D.R.O. 1, Phys. Rev. 165 (1968) 1699 [ 3 ] ALEXANDER (G.) e t a l . ,

el-~vizeidelber~

^{c o l -}

l a b o r a t i o n , p a p e r 7 7

141 GORDON (H.A.) e t al., BNL, p a p e r 1 9 [ 5 ] WILLIAMS (P.K.), Phys. Rev. (1970) 1312 [ 6 ] HARARI (H. ), Phys. Rev. L e t t e r s 2 6 (1971) 1400 [7

]

BOUCHEZ (J. ) and MALLET (J. 1, p a p e r 289 [8 ] EISENBERG (Y. e t a l .

,

Weizmann I n s t i t u t e , pa-

p e r 312

[9

1

BELL ( I .G. ) e t a l . , Durham-Birmingham-Rutherford c o l l a b o r a t i o n , p a p e r 247

[lo]

KARSHON (U.) e t a l . , Weizmann I n s t i t u t e , p a p e r 313

[ 1 1

]

CHALOUPKA (v. ), p r i v a t e communication [12] COHEN (D. ) et al., p a p e r 9 3

[131

BLOODlYORTH ( I . J, e t a l . , T o r o n t o , p a p e r 180 [14

1

CIAPETTI (G. ) e t a l . , CERN-Birmingham-Brussels-

Mons-Saclay-Paris c o l l a b o r a t i o n , p a p e r 256 1151 ANSORGE (R.E. ) e t al., Cambridge, p a p e r 249 El6

1

ATHER'IDN (H. W. ) e t a l . , CERN-Prague c o l l a b o r a -

t i o n , p a p e r 254

[17] CHARRIERE (G. ⁾e t al.

,

CERN-Munich-Mons-Brussels c o l l a b o r a t i o n , p a p e r 292

[ 1 8 ] CHARLESWORTH (J.A. ) e t a l .

,

Rutherford-Birmingham Durham c o l l a b o r a t i o n , p a p e r 274

[19] TENNES (A.G. )

,

VERSTEEG (M.F. )

,

WOLTERS (G.F. )

,

p a p e r 250

[ 2 0 ] LYONS ( L . ) e t a l . , Weizmann I n s t i t u t e , p a p e r 347.