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Submitted on 1 Jan 1973
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CHARGE-EXCHANGE RESULTS FROM SERPUKHOV
V. Kutin
To cite this version:
V. Kutin. CHARGE-EXCHANGE RESULTS FROM SERPUKHOV. Journal de Physique Colloques,
1973, 34 (C1), pp.C1-290-C1-291. �10.1051/jphyscol:1973135�. �jpa-00215215�
V.M. KUTIN
CHARGE-EXCHANGE RESULTS FROM SERPUKHOV
V.M. KUTIN
I n s t i t u t e of High Energy P h y s i c s , Serpukhov, USSR
D i f f e r e n t i a l c r o s s s e c t i o n s f o r t h e charge-exchange i n t h e i n t e r v a l 0
< -t <
1.5 (GeV/c) 2.
r e a c t i o n s
(I) -
(IV) have been measured i n t h e Ser- F o r r e a c t i o n ( I I ) , t h e p a r a m e t r i z a t i o n of t h e A2 pukhov energy range. These r e a c t i o n s t r a j e c t o r y i s n o n l i n e a r :c + p -+ x O + n
,
(1)C + p v O + n
,
(11)K - + p -t -a K + n
,
(111)- -
p + p n + n
,
(IV)a r e among t h e s i m p l e s t p r o c e s s e s of exchange s c a t - t e r i n g , because t h e asymptotic behaviours of t h e i r a m p l i t u d e s a r e dominated by t-channel c o n t r i b u t i o n s from one o r two p o l e s with t h e quantum numbers of t h e
p
and A2 mesons. F i g u r e s showing some of t h e r e s u l t s a r e included i n Amaldi's r a p p o r t e u r t a l k .Measurements f o r t h e r e a c t i o n s I and I 1 were t a k e n a t i n c i d e n t momenta p
=
2 1 , 2 5 , 32.5, 40 and 48GeV/c0 0
[I
1 .
Photon p a i r s from K (rl ) decay were d e t e c t e d by a n o p t i c a l s p a r k spectrometer. The d i f f e r e n t i a l c r o s s s e c t i o n f o r ( I ) has a maximum a t-t
N 0.03 ( ~ e ~ / c ) ' ; t h e n i n t h e i n t e r v a l 0.1< - t
<O.G(GeVc) 2 i t f a l l s r a p i d l y w i t h i n c r e a s i n g- t ,
and f o r-t >
0 . 6 (GeV/c) 2i t
goes through a second maximum.I n t h e momentum range 6
5
P5
50 GeV/c t h e d i f f e - r e n t i a l c r o s s s e c t i o n a t z e r o a n g l e i s d e s c r i b e d by t h e power f u n c t i o nFrom Eq. ( 1 )
i t
f o l l o w s t h a t t h e v a l u e of t h ep
t r a - j e c t o r y a tt =
0 i sT h i s v a l u e i s i n disagreement w i t h d a t a f o r t h e to- t a l c r o s s s e c t i o n d i f f e r e n c e A~('JC')
,
and t h e d i s - crepancy corresponds t o two o r t h r e e s t a n d a r d devia- t i o n s . The forward peak s h r i n k s a s energy i n c r e a s e s . The c r o s s s e c t i o n f o r r e a c t i o n ( 1 ) i n t h e r e g i o n of t h e second maximum d e c r e a s e s a s p-2'8t0.1.The
p
t r a j e c t o r yi s
parametrized by a l i n e a r func- t i o na , ( t )
=
(0.56+
0.02)+
(0.97 +_ 0.04)t ( 3 )I n t h e r e g i o n
t
N O,
t h i s A2 t r a j e c t o r y goes c o n s i d e r a b l y h i g h e r t h a n v a l u e s deduced from d a t a a t lower e n e r g i e s . The forward s c a t t e r i n g cone shrinks slowly a s energy i n c r e a s e s , f o r 0.2- < -t _<
1,
and a t- t =
1 . 1 ( ~ e V / c ) ' t h e d i f f e r e n t i a l c r o s s s e c t i o n h a s a f l a t minimum.C r o s s s e c t i o n s f o r r e a c t i o n s (111) and(1V) have been measured a t 25, 35 and 39 GeV/c [ 2 , 3 1
.
The energy dependence a tt =
0 f o r r e a c t i o n ( I I 1 ) i s d e s c r i b e d byand i s below t h e o p t i c a l l i m i t d e f i n e d by t h e t o t a l c r o s s s e c t i o n d i f f e r e n c e
Am =
~ ( K - P )- ~(b-n) ,
w i t h d a t a above 25 GeV/c. T h i s d i s c r e p a n c y i s probably connected w i t h t h e c o r r e c t i o n f o r nucleon s c r e e n i n g i n t h e deuteron. To remove t h e discrepancyi t
i s s u f f i c i e n t t o i n c r e a s e t h e Glauber c o r r e c t i o n by 13%.The forward peak of K-p -+ p n s c a t t e r i n g s h r i n k s slowly w i t h i n c r e a s i n g energy ; t h e s l o p e parameter b i s d e s c r i b e d by a l o g a r i t h m i c s-dependence :
where b i s measured i n ( ~ e v / c ) ' and
- - so =
10 GeV 2.
The c r o s s s e c t i o n f o r pp -t nn c o n t i n u e s t o f a l l a s r a p i d l y , w i t h i n c r e a s i n g energy, a s a t p
2
SGeV/c :A narrow peak
i s
c l e a r l y s e e n i n d C / d t ( 0< -t
<
0.02 (GeV/c) 2 ), which i s analogous t o t h a t observed a t lower e n e r g i e s . The c r o s s s e c t i o n d e c r e a s e i s e q u a l l y r a p i d a t a l l t - v a l u e s ( u l / p 2 ). T h i s means t h a t t h e c o n t r i b u t i o n s ofp
and A2 exchange a r e n o t y e t important and t h e asymptotic regime f o r reac- tion(1V)occurs a t c o n s i d e r a b l y h i g h e r e n e r g i e s .Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1973135
CHARGE-EXCHANGE RESULTS FROM SERPUKHOV
[ I ] BOMTOV (V.N.) et a l . , papers 357 and 358 [ 2 ] B O M M V ( V . N . ) e t a l . , papers 425 and 426
REFERENCES
[31 BALOSHIN (o.N. ) et ax., paper 444.