SUMMARY OF THE SESSIONS ON LEPTON-HADRON PHYSICS

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SUMMARY OF THE SESSIONS ON LEPTON-HADRON PHYSICS

D. Haidt

To cite this version:

D. Haidt. SUMMARY OF THE SESSIONS ON LEPTON-HADRON PHYSICS. Journal de Physique Colloques, 1982, 43 (C3), pp.C3-5-C3-21. �10.1051/jphyscol:1982301�. �jpa-00221854�

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CoZZoque C 3 , supple'rnent a u n o 12, Tome 43, de'cembre 1 9 8 2 p a g e C3-5

SUMMARY OF THE SESSIONS ON LEPTON-HADRON PHYSICS

D . Haidt

DESY, N o t k e s t r a s s e 8 5 , 2000 Hamburg 52, F.R.G.

I n t r o d u c t i o n

This r e p o r t gives a s h o r t r6sum6 o f t h e two sessions on lepton-hadron s c a t t e r i n g . Three t o p i c s , namely s t r u c t u r e f u n c t i o n s , hadronic f i n a l s t a t e s and prompt leptons

i n beam dump experiments, a r e summarized here, o t h e r t o p i c s a r e found i n t h e summaries o f L. Sehgal and V. Barger.

1. S t r u c t u r e Functions

Deep i n e l a s t i c l e p t o n s c a t t e r i n g o f f nucleons o r n u c l e a r t a r g e t s has revealed t h e composite s t r u c t u r e o f nucleons. The l e p t o n i n t e r a c t s w i t h t h e quarks i n s i d e t h e nucleon through n e u t r a l and charged spacelike c u r r e n t s . A l l electroweak phenomena a r e s o f a r w e l l described by t h e standard model based on t h e gauge group U(1) x SU(2).

These electroweak c u r r e n t s a r e t h e r e f o r e i d e a l t o o l s t o i n v e s t i g a t e t h e s t r u c t u r e of the nucleon. The given gauge s t r u c t u r e i m p l i e s r e l a t i o n s between t h e s t r u c t u r e f u n c t i o n s observed i n charged l e p t o n experiments and i n charged and n e u t r a l c u r r e n t induced n e u t r i n o and a n t i n e u t r i n o experiments. The major i n t e r e s t i n measuring s t r u c t u r e f u n c t i o n s i s t h e understanding o f t h e i r s c a l i n g v i o l a t i o n . Rather good and c o n s i s t e n t data e x i s t from various experiments on i s o s c a l a r t a r g e t s . Least known i s the l o n g i t u d i n a l s t r u c t u r e f u n c t i o n r e l a t e d t o t h e exchange o f h e l i c i t y 0 gauge bosons. Another c l a s s o f experiments deals w i t h l e p t o n s c a t t e r i n g o f f simple t a r g e t s l i k e hydrogen and deuterium. Although such experiments are based on smaller s t a t i s t i c s they are o f importance i n d i s e n t a n g l i n g the f l a v o u r composition o f t h e quarks i n t h e nucleon. Furthermore, i n comparing measurements on deuterium w i t h measurements on complex (almost i s o s c a l a r ) t a r g e t s n u c l e a r e f f e c t s may be tested.

This t o p i c can be k e p t s h o r t , since F. E i s e l e i s d e a l i n g e x t e n s i v e l y w i t h s t r u c t u r e functions i n h i s plenary t a l k . Table 1 summarizes t h e c o n t r i b u t i o n s t o t h i s Conference.

( a ) ~ y ~ s _ s _ ~ ~ ] ~ ~ ~ ~ ] y n _ I ~ m ~ : ~ - _ s u _ ~ y u _ ~ ~

1

This sumrule, I F 3 ( x ) d x = #q - #q ^{= 3 ( Q 2 + a),} o r i g i n a l l y d e r i v e d from c u r r e n t

0

algebra measures the number o f valence quarks i n t h e nucleon, which equals 3 i n t h e quark model. Fig. 1 shows t h e data o f two experiments [3,41. The e r r o r s are s t a t i s t i - c a l . The sumrule i s s a t i s f i e d even a t l o w Q" provided t h e c o n t r i b u t i o n o f e l a s t i c events i s included. No o r l i t t l e v a r i a t i o n w i t h ^{Q 2} i s observed. I t should, however,

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1982301

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Table 1: C o n t r i b u t i o n s t o t h i s Conference Experiment

BEBC ABCMO v,v - H 2 ABCDLOS v , v - Ne BEBC-GGM CCFRR v,v - Fe CDHS v,v - Fe

CDHS v,V H~

CHAR14 v :,

BCDMS V C EMC vFe, Hz, D2

.---

Contr. Paper

# 596

# 708

# 706

# 318

# 590

# 749

...

Q u a n t i t y

d/u F2, xF3

fF3 F2, xF3, /F3 F2, xF3. - q xG(x) R

dv/uv, T/U

NC x - d i s t r . F2, R

F ~ R o N / F ~ ~ , R F2, F;, P d/u --- F2

Reference

1 2 3 4 5 6 7 8 8

i

9 10 10 10 11 Speaker

Schmid

Shaevitz

Merl o Merl o

Edwards Edwards Edwards

--___--_---_-_=---=---=

be noted t h a t t h e i n t e g r a l gets important c o n t r i b u t i o n s a t small x. For f i x e d ^Q2 and g i v e n - n e u t r i n o energy spectrum t h e r e i s a s m a l l e s t value o f x. The small x r e g i o n i s t h e r e f o r e parametrized as xF3 ( x ) = AX^ w i t h a = 0.5.

1 I . ... ^I . ..'...' ^{I '} " " " ' I ' """'1

x CCFRR (Ref.4

--Partonmob.lpr.diction -OCD prdietion XI-aJx

1 .

F i g u r e 1. The Gross-Llewellyn-Smith sumrule as a f u n c t i o n o f Q 2 .

New data were presented by CDHS r81, EMC pHZ and yFe [I01 and BCDMS 1101.

R = uL/aT FL/F2 i s r e l a t e d t o t h e l o n g i t u d i n a l s t r u c t u r e f u n c t i o n FL F2 - 2xF1.

I n t h e n a i v e quark parton model FL = 0 (Callan-Gross r e l a t i o n ) . R i s important f o r the e x t r a c t i o n o f F2. The d i f f e r e n t i a l y and v + T cross s e c t i o n s a r e p r o p o r t i o n a l t o 1 + ( I - Y ) ~ - y" and thus r a t h e r i n s e n s i t i v e t o R. The CDHS c o l l a b o r a t i o n has

presented considerably improved values f o r R a t l a r g e x (see f i g . 2). The idea o f t h e new method c o n s i s t s i n e x p l o i t i n g t h e q u a n t i t y

A t l a r g e x t h e q u a n t i t y A i s known e x p e r i m e n t a l l y t o be n e a r l y zero, thus a t i g h t upper l i m i t can be obtained f o r R. Averaging over 0.4 < x < 0.7 g i v e s

<R> 5 0.006 2 0.012 + 0.025. I n t h e r e g i o n x < 0.4 R i s s t i l l badly measured.

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x CDHS

F i g u r e 2. Pleasurements o f R =FL/2xF1 averaged over t h e hadron energy as a f u n c t i o n of t h e Bjorken v a r i a b l e x. The data from CDHS w i t h t h e new method a r e - upper 1 im i t s .

New r e s u l t s from v a r i o u s experiments (see t a b l e 1 ) were presented. The h i g h s t a t i s t i c s e x p e r i m e n t s w i t h f i n a l r e s u l t s agree i n shape w i t h each o t h e r a t t h e 10- 15% 1 eve1 . However, t h e p r e l iminary data presented by t h e CCFRR c o l l aboration [ 4 1

disagree s y s t e m a t i c a l l y when compared, f o r instance, w i t h t h e data o f t h e CDHS c o l l a b o r a t i o n 15 1 . A1 ready t h e q u a n t i t i e s 1 (ov+ ov) measured i n t h e CCFRR experiment show a s u b s t a n t i a l energy dependence, unless t h e d e v i a t i o n from constant behaviour be a s c r i b e d t o n o r m a l i z a t i o n d i f f e r e n c e s . It should be noted t h a t t h i s experiment c o n s i s t s o f a combination o f 5 independent beam s e t t i n g s .

The new, p r e l i m i n a r y data o f t h e BCDMS c o l l a b o r a t i o n [lo] w i l l be discussed i n con- t e x t w i t h o t h e r data by F. Eisele.

The EMC c o l l a b o r a t i o n 1101 has e x t r a c t e d t h e s t r u c t u r e f u n c t i o n F2 both from t h e i r i r o n and deuterium data. The r a t i o i s p l o t t e d i n f i g . 3 versus t h e s c a l i n g v a r i a b l e x and i s n o t constant, as n a i v e l y expected, b u t decreases s y s t e m a t i c a l l y w i t h i n c r e a - s i n g x by about 30%. No explanation has as y e t been p u t forward. This e f f e c t under- l i n e s the importance o f l e p t o n s c a t t e r i n g experiments u s i n g simple t a r g e t s l i k e hydrogen and deuterium.

F i g u r e 3. R a t i o o f t h e f u n c t i o n F2 measured on i r o n and deuterium vs x.

The dashed l i n e represents t h e e f f e c t due t o Fermi motion. The sys- tematic e r r o r ( n o t i n c l u d e d ) amounts t o about 0.1.

F 2 0 2 1.2

1.0

0.8

0 .2 .4 .6 X

I

Q': 50 G ~ V ' -

EMC

-

-11 I ,

1,

--+---+- t +t-t-+-

-

t

- ^I

I :

The CHARM collaboration 191 has contributed a new piece of information in measuring the x d i s t r i b u t i o n s in v and < neutral current reactions. Under simplifying assump- tions one obtains:

where u R,L, dR,L a r e the neutral current couplings and k referring t o v resp. 7.

The nucleon s t r u c t u r e functions in neutral current interactions (see f i g . 4) show no s i g n i f i c a n t difference t o those measured in charged current interactions a s ex- pected by the quark model and the standard model of electroweak interactions.

Figure 4. Neutral current x-distributions f o r v and ; interactions.

( e !_a-r_t._t- ?_t-r-u_c_t-u-r_e- f_~_n-c_t~i~o_n-s

The sea quark d i s t r i b u t i o n xq (x,Q2) = x (u + a ⁺ 2y) i s well measured [51. With t h e i r < induced opposite sign dimuon sample the CDHS collaboration has deduced the s t r u c t u r e function of t h e strange sea L7j. I t agrees in shape with the measured a n t i - quark d i s t r i b u t i o n q. Using f u r t h e r assumptions they get

which suggests a nonsymmetric sea. However, a/ii i s compatible with 1 within 30% 18).

Three collaborations have presented r e s u l t s on the r a t i o of the d and u s t r u c t u r e functions [I ,8,10]. The data agree with each other ( f i g . 5) f o r x > 0.3. The CDHS group deduced the valence d i s t r i b u t i o n s . No data e x i s t beyond x = 0.8, where theoretical models give d i f f e r e n t predictions.

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F i g u r e 5. R a t i o o f quark s t r u c t u r e f u n c t i o n s d ( x ) / u ( x ) vs x.

The charmed sea i s s t i l l r a t h e r b a d l y known.

The gluon d i s t r i b u t i o n f u n c t i o n i s d e r i v e d by t h e CDHS c o l l a b o r a t i o n [6] from the

Q2 e v o l u t i o n o f F2 and xq.

2. Results, on Hadronic F i n a l States

New r e s u l t s on f i n a l s t a t e s i n lepton-hadron s c a t t e r i n g experiments a r e summarized i n t a b l e 2. Some c o n t r i b u t i o n s a r e a l r e a d y i n t h e i r f i n a l form and published. They w i l l n o t be commented here.

I

# u

'

t

Contr. Paper 348 456 61 2 I

712 1

Four bubble chamber experiments presented data on charged hadron m u l t i p l i c i t i e s . The f o l l o w i n g t a b l e shows t h a t t h e s i z e s o f t h e v and < event samples a r e q u i t e s u b s t a n t i a l .

1

I Experiment

I

SKAT 1 15'

1

!

/

i

I ^{I 1}

I L i q u i d I Freon _' D2 Hz-TST 1

Table 2

---- Exeeriment BEBC WA21

WA24 WA25 WA59 15 ' FNAL IMSTT vDp I I F 3 Ne

CDHS SKAT

GGM EMC - NA2

EMC - NA9

---=--- ---S_eea_ker--- Schmid

V i gnaud

Snow Snow Sehgal

Becks

Becks Becks --- 4 u a _ n _ t 1 3 ~ ~ ~ - ~ . ~

mu1 t i p 1 i c i t y charge p r o p e r t i e s fragmentation cos @

m u l t i p l i c i t y

"'5

p e x c l u s i v e p bremsstrahl ung

NC production c-fragmentation

KO, A

h* production

COS 6 , PT Q~ e v o l u t i o n n u c l e a r t a r g e t s heavy quarkonium open charm P/., p, B

PT* Y 2

' _ - ~ _ o n _ t r ~ ~ i a _ ~ e r - ~ ~ - ~ ~ R e _ f ~

# 712

# 711

# 612

# 543

# 737

# 456

# 756

# 303

# 704

# 318

# 504

# 347, # 348

# 747

# 750, # 795

# 748

# 751

# 752

# 773

----

13 14 15 16 17 18 19 21 2 2 7 23 24 25 26,27 28 29 30 3 1 32 3 2

C3-12 JOURNAL DE PHYSIQUE

Two groups emphasize t h e importance o f c o r r e c t mass assignment. The BEBC-TST group has developed a method t o i d e n t i f y protons i n t h e f i n a l s t a t e [151. The ABCMO c o l l a b o r a t i o n [13! (BEBC-WA21) performed a thorough study u s i n g t h e LUND Monte C a r l o

[201 and found t h a t about 17% o f t h e p o s i t i v e and about 8% o f t h e n e g a t i v e hadrons migrate from the b a d w a r d t o t h e forward hemisphere i n t h e hadrons' c e n t r e o f mass

system, on account o f systematics, whereas o n l y 2% from forward t o backward.

Due t o t h e poor d e t e c t i o n o f n e u t r a l s i n bubble chambers f i l l e d w i t h l i g h t l i q u i d s the e f f e c t o f t h e n e u t r i n o energy e s t i m a t i o n must be c a r e f u l l y taken i n t o account. As a consequence the m u l t i p l i c i t y d i s t r i b u t i o n s o f forward and backward p a r t i c l e s a r e now m o d i f i e d compared t o the r e s u l t s presented a t t h e Bonn conference

1361. F i g . 6 shows t h e i r c o r r e c t e d m u l t i p l i c i t y d i s t r i b u t i o n s [I31 w i t h t h e obser- v a t i o n t h a t f o r vp <n;> l e s s than < n i > and f o r u p <n;> c3 The v-data o f t h e BEBC-TST c o l l a b o r a t i o n c o n f i r m t h i s behaviour.

The experiment i n t h e SKAT bubble chamber L24.1 provides data a t s m a l l e r c e n t r e of mass energies ranging f r o m t h r e s h o l d u n t i l w2 ^fi 15 G ~ v ' . The d i s p e r s i o n D- depends l i n e a r l y upon <n-> except f o r very l o w average m u l t i p l i c i t i e s o f negative hadrons.

I n the experiment u s i n g t h e FNAL 15' bubble chamber [18:1 f i l l e d w i t h deuterium m u l t i p l i c i t y d i s t r i b u t i o n s on protons and neutrons are obtained ( f i g . 7).

Figure 6. Average charged m u l t i p l i c i t i e s i n forward and backward hemispheres vs W 2 .

Data from r e f . 1.

D. H a i d t

i n forward and backward hemispheres 6

5 -

C 4 c ' 3

V 2

O

4

vs w L . Data from r e f . 18.

Many f e a t u r e s o f t h e data can be q u a l i t a t i v e l y understood i n terms o f q- and qq- fragmentation [ 3 7 ] . For instance, t h e mu1 t i p l i c i t y o f forward hadrons (u-quark f r a g - ments) should be t h e same i n vp and vn, whereas t h e backward m u l t i p l i c i t y i n vp

(due t o uu-fragments) should be b i g g e r than i n vn (due t o ud-fragments). This i s born o u t i n f i g . 7. The r e l a t i o n between d i s p e r s i o n D- and <n-> appears t o be t h e same f o r vp and vn [18].

I U t 8 ~

(a) xF>O -

- b

4 + ^-

- : e -

1

- ⁰ 0 -

? 0 u p -tp- x++

0 O P

I - . u n --'p,-~+ -

I I I I

(b) x F < O

- -

( b ) Charm Fragmentation ...

The CijHS [7] and t h e EMC r311 c o l l a b o r a t i o n s have presented measurements o f t h e charm fragmentation f u n c t i o n u s i n g t h e i r mu1 ti-muon data. The momentum spectrum o f v+ i n

' I

v -induced charged c u h e n t i n t e r a c t i o n s contains i n f o r m a t i o n on charm fragmentation.

The basic process i s vp(d,s) P + v-c and c -. p+v (s,d). F i g . 8 shows f i t s t o t h e L'

measured CI+ d i s t r i b u t i o n and t h e e x t r a c t e d charm d i s t r i b u t i o n . The average f r a c t i o n a l momentum o f t h e charmed hadron i s <z> = 0.68 + 0.08 i n c l u d i n g u n c e r t a i n t i e s due t o branching r a t i o s o f D-mesons, a/K background and charmed quark mass.

The EMC c o l l a b o r a t i o n f i n d s a l s o t h a t t h e charm fragmentation f u n c t i o n i s hard as opposed t o t h e s o f t u,d,s quark fragmentation f u n c t i o n s . T h e i r data on dimuons and trimuons a r e w e l l described by t h e photon gluon f u s i o n model [30,31 1. F i t t i n g t h e

F i g u r e 7. Average charged mu1 t i p 1 i c i t i e s

C3- 14 JOURNAL DE PHYSIQUE

f u n c t i o n Dc(z) ^N exp(az) they o b t a i n a = 1.6 _+ 1.6, where t h e e r r o r contains syste- matic u n c e r t a i n t i e s o f t h e model parameters, i n p a r t i c u l a r t h e shape o f t h e gluon d i s t r i b u t i o n f u n c t i o n . I n t h e f i g . 9 two fragmentation schemes are shown.

F i g u r e 9 . Energy d i s t r i b u t i o n s o f decay muons from charmed meson decays

a) Z,, = E,,/Ehad f o r dimuon events b ) Zu,, = (EP1 + EU2)/Ehad f o r trimuon

events.

F i g u r e 8. D i s t r i b u t i o n o f n e u t r f n o dimuon eventsas a f u n c t i o n o f zL determined by t h e momentum o f t h e decay muon and t h e hadron shower energy. The curves are comparisons w i t h Monte C a r l o p r e d i c t i o n s . The i n l e t shows t h e f i t t e d charm fragmen- t a t i o n f u n c t i o n .

D. Haidt

( c ) I n c l u s i v e P a r t i c l e Production ...

The LUND model [20-] describes f a i r l y we1 1 deep i n e l a s t i c l e p t o n hadron s c a t t e r i n g . It t r e a t s b o t h quark and diquark fragmentation and accounts, t h e r e f o r e , f o r meson and baryon production. The ABBPPST c o l l a b o r a t i o n [16] (BEBC-WA 25) w i t h t h e i r v and

- v i n t e r a c t i o n s on deuterium has a unique t e s t i n g ground f o r t h e f l a v o u r

dependence o f quark and diquark fragmentation. Rather than comparing t h e corrected, unfolded data w i t h t h e model p r e d i c t i o n s , they have b u i l t i n t o t h e model a l l known experimental u n c e r t a i n t i e s , l i k e n e u t r i n o energy c o r r e c t i o n , mass assignments, r e s o l u t i o n , kinematical c u t s e t c . and compare d i r e c t l y w i t h t h e uncorrected data.

Based on about 6500 v p + vn and 3800 v p + <n a f t e r c u t s (W 2 > 5 G ~ v ~ , Q* > 1 GeV2) t h e p r e d i c t i o n o f t h e LUND model f o r t h e Feynman x F - d i s t r i b u t i o n s agrees w e l l w i t h t h e data both f o r xF > 0 ( c u r r e n t fragmentation r e g i o n ) and xF < 0 ( t a r g e t fragmentation region). A d e t a i l e d study o f strange p a r t i c l e p r o d u c t i o n has been c a r r i e d out. The observed r a t e s and x F - d i s t r i b u t i o n s f o r ^KO and A p r o d u c t i o n a r e w e l l reproduced pro- vided the fragmentation parameter d e s c r i b i n g t h e f r a c t i o n o f s? p a i r s compared t o any q q p a i r s i n t h e cascade i s assumed t o be 0.07. Features l i k e t h e narrow x - d i s t r i - b u t i o n o f A's produced i n v n + A'P + anything, a s c r i b e d t o i n t e r a c t i o n s w i t h t h e strange sea i n t h e nucleon, are w e l l reproduced. I n c i d e n t a l l y , given t h i s i n t e r - p r e t a t i o n about 45% o f t h e A i n v n ⁺ p+A + x a r e p r e d i c t e d t o be produced i n asso- c i a t i o n w i t h a charmed p a r t i c l e . Also t h e p r o d u c t i o n o f strange resonances

(K** (892), X (1385)) has been i n v e s t i g a t e d and found t o p l a y an important r S l e . Fig. 10 shows t h e x F - d i s t r i b u t i o n o f K*+ and K*- produced i n v charged c u r r e n t i n t e r - actions. Again, good agreement i n r a t e and shape w i t h the LUND model i s found. The data on strange baryon production imply t h a t t h e diquark does n o t always fragment as one u n i t , b u t breaks up w i t h a p r o b a b i l i t y o f about 50%.

The EMC c o l l a b o r a t i o n [32] deduced t h e r a t i o

which i m p l i e s a production r a t e o f v e c t o r t o pseudoscalar p a r t i c l e s i n t h e F i e l d - Feynman j e t model compatible w i t h 1. The EMC-NA9 c o l l a b o r a t i o n has shown f i r s t r e s u l t s based on t h e i r v e r t e x d e t e c t o r r 3 q . With t h i s d e t e c t o r i t w i l l be p o s s i b l e t o i n v e s t i g a t e a l s o t h e t a r g e t fragmentation region.

A

: production has been i n v e s t i g a t e d i n a n e u t r i n o deuterium experiment by t h e IIMST c o l l a b o r a t i o n [I91 y i e l d i n g

JOURNAL DE PHYSIQUE

F i g u r e 10. I n v a r i a n t mass d i s t r i b u t i o n o f KO and n+ w i t h (K*)' peak and x-Feynman d i s t r i b u t i o n s o f (K*)' observed i n v-induced i n t e r a c t i o n s . Data from r e f . 16.

More r e s u l t s on p r o t o n and a n t i p r o t o n p r o d u c t i o n i n t h e c u r r e n t r e g i o n have been presented by the EMC c o l l a b o r a t i o n [32J. Fig. 11 shows a s t r o n g increase o f the r e l a t i v e baryon r a t e s w i t h i n c r e a s i n g t r a n s v e r s e momentum w i t h r e s p e c t t o t h e j e t a x i s .

Neutral c u r r e n t induced @ p r o d u c t i o n has been observed by t h e CDHS c o l l a b o r a t i o n [22].

Charged and strange p a r t i c l e production has a1so:been s t u d i e d i n low energy v and i n t e r a c t i o n s observed i n t h e bubble chamber SKAT f i l l e d w i t h f r e o n p3,241.

A t these energies events a r e n o t y e t j e t l i k e . ( d l _c_os@ d i s t r i b u t i o n

Two c o l l a b o r a t i o n s have i n v e s t i g a t e d t h e azimuthal dependence o f charged hadrons i n the c u r r e n t fragmentation r e g i o n w i t h respect t o the l e p t o n s c a t t e r i n g and t h e hadron p r o d u c t i o n plane. F i r s t o r d e r QCD expectation i s <cos@ > ^rv, -0.1, b u t a l s o on t h e basis o f t h e quark parton model w i t h p r i m o r d i a l kT an e f f e c t p r o p o r t i o n a l t o -k T /Q i s predicted.

Protons/pos hadrons Preliminary

F i g u r e 11. R e l a t i v e proton and a n t i p r o t o n p r o d u c t i o n observed by EMC ( r e f . 32).

The BEBC-WA59 c o l l a b o r a t i o n [I71 observe i n t h e i r 7-data t h e f o l l o w i n g averages o f cos$ f o r nf and n-:

5 0

4 0 -

3 0 -

t

! ^Data ;; ^{1.10 i 0.45}

'

/

j MC : 0.0 + 0.7 1.29 + 0.45 1.30 + 0.8

'

Antiprotons/neg.hadrons - Preliminary

( b )

Systematic e f f e c t s have been determined by a Monte C a r l o c a l c u l a t i o n assuming a f l a t

$-dependence. The data show t h a t <cos$> i s s i g n i f i c a n t l y negative. Also n o ' s have been i n v e s t i g a t e d . The i n v a r i a n t mass d i s t r i b u t i o n o f y and p shows an enhancement a t M < 0.014 a s c r i b e d t o muon bremsstrahlung. I n n e r muon bremsstrahlung i s s t u d i e d 2 i n a c o n t r i b u t i o n t o t h i s conference [211 i n t h e FNAL experiment E 546 ( V Ne/H2 1 5 ' ) and found i n agreement w i t h t h e QED p r e d i c t i o n .

The EMC c o l l a b o r a t i o n p6[ observes c l e a r l y a n e g a t i v e <cos$>. F i g . 12c shows t h a t t h e e f f e c t increases w i t h i n c r e a s i n g z. Furthermore, <cos2@ i s very small and posi- t i v e .

The EMC c o l l a b o r a t i o n 1271 has found t h a t t h e t r a n s v e r s e momentum o f f a s t forward hadrons i s p a r t i a l l y compensated by o t h e r forward hadrons, as shown i n f i g . 13.

The LUND model accounts f o r t h i s behaviour by a l l o w i n g f o r s o f t gluon emission [33!.

Then, a value o f <kT> as low as 0.2 2 G ~ V / C ' i s s u f f i c i e n t t o p r o v i d e a good f i t t o t h e d i s t r i b u t i o n .

C3-18 JOURNAL DE PHYSIQUE

, ^LO G e v v < 100 GSV

5

P: ( G ~ v ' )

L GeV

p: (GPV')

- Model calculation

-0 3 I

0 0.2 0 1 , 0 6 0 8 1 0

z

F i g u r e 12. Data from EPIC

-- 2

a , b ) hadron p r o d u c t i o n o f f 3 d i f f e r e n t n u c l e i v e r s u s pT ( r e f . 2 5 ) .

c ) lloments o f t h e azimuthal d i s t r i b u t i o n o f charged hadrons v s f r a c t i o n a l e n e r g y ( r e f . 2 6 ) .

Y *

F i g u r e 13. T r a n s v e r s e momentum f l o w and b a l a n c i n g component vs cms r a p i d i t y ( r e f . 2 7 ) .

A comparison o f charged hadron p r o d u c t i o n i n muon n u c l e u s s c a t t e r i n g f o r v a r i o u s n u c l e i u s i n 9 t h e EMC a p p a r a t u s 129 shows no s u b s t a n t i a l A-dependence ( f i g . 1 2 a , b ) . ( s ) Q-~Evolutlon 2

The Q 2 dependence o f charged hadron f r a g m e n t a t i o n f u n c t i o n s have been s t u d i e d by EMC [28:! and BEBC-WA25 1161 and a p p e a r s t o be s m a l l .

D. H a i d t

3. Beam Dump Experiments

There were two presentations on prompt l e p t o n production. The Neutrino beam dump experiment E-613 o f t h e MWOWF c o l l a b o r a t i o n 1341 w i t h a f u l l and a 1/3 d e n s i t y tungsten dump y i e l d e d 830 s i n g l e muon and 752 inuonless events. The prompt s i g n a l i s obtained by e x t r a p o l a t i o n t o i n f i n i t e density. I f c e n t r a l production o f DE gives r i s e t o t h e observed prompt n e u t r i n o i n t e r a c t i o n s t h e DD production cross s e c t i o n parametrized as

r e s u l t s i n (16 + ³ + 3) yb f o r n = 3 and a = 2. There i s no evidence f o r an important nCD d i f f r a c t i v e charm production. The r a t e o f #ve/#v i s found c o n s i s t e n t w i t h 1

IJ provided E,, > 30 GeV.

F u r t h e r r e s u l t s d e a l i n g w i t h supersymmetry l i m i t s [34] a r e discussed i n t h e t a l k o f L. Sehgal .

Forward p r o d u c t i o n o f charmed p a r t i c l e s t a t e s and prompt muons have been s t u d i e d i n 350 GeV p i r o n and 278 GeV .rr- i r o n beam dump experiment E - 595 [35]. The prompt muon r a t e s were found t o be

#p- - 2.23 * 0.29 i n n- Fe

= 1.10 + 0.21 i n p Fe and - -

#M+ #cl+

f o r EM > 20 GeV. The observed momentum d i s t r i b u t i o n s a r e f i t , as above, t o ( I - x ) ~ r e s u l t i n g i n n = 6 + 0.8 f o r pf i n p Fe, b u t n = 3.4 1.0 resp. 1.3 + 0.8 f o r y+

resp. y- i n IT- Fe. From t h e data w i t h p > 50 GeV i t can be concluded t h a t t h e i n - C1

t r i n s i c charm component i n the proton and p i o n wavefunctions i s l e s s than z.Io-~.

Acknowledgements

I would l i k e t o thank Drs. J.J. Aubert and R. Petronzio f o r t h e k i n d i n v i t a t i o n and t h e i r h e l p d u r i v g t h e p r e p a r a t i o n o f t h e t a l k . I appreciated discussions w i t h Prof. Eisele, Prof. Snow, Drs. K. Becks, J. Gayler, J.P. Merlo, P. Schmid, W. S c o t t and A. Vayaki. Thanks t o Mrs. S. P l a t z f o r t h e c a r e f u l t y p i n g o f t h e manuscript.

References

[I] Talk by P. Schmid

Contr. Paper # 596, D i r e c t determination o f the quark d e n s i t y r a t i o d ( x ) / u ( x ) i n the proton from vp and v p i n t e r a c t i o n s , ABCMO C o l l a b o r a t i o n (BEBC-WA 21) [2] P.C. B o s e t t i e t a1 . ^, PITHA 82-04 (Aachen P r e p r i n t 1982)

[3] T. Bol ognese e t a1 . , CERN-EP/82-78

C3-20 JOURNAL DE PHYSIQUE

[4] Talk by M.H. Shaevitz

R.E. B l a i r e t al., N e u t r i n o Charged Current S t r u c t u r e Functions, UR-831 COO-3065-339

[q H. Abramowicz e t a1 ., (CDHS), Z. Phys. C13 (1982) 199, Contr. Paper # 708 [6] H. Abramowicz e t a l . , (CDHS), Z. Phys. C12 (1982) 289, Contr. Paper # 706 [7] H. Abramowicz e& a1 . , (CDHS), Experimental Study o f opposite s i g n dimuons pro-

duced i n v and v i n t e r a c t i o n s , CERN-EP/82-77 and Contr. Paper # 318 r81 T a l k by J.P. Merlo

- -

[9] Contr. Paper # 590, J.V. A l l a b y e t a l . , (CHARM), CERN-EP/82-85

Experimental Study o f x - d i s t r i b u t i o n s i n semileptonic n e u t r a l c u r r e n t n e u t r i n o r e a c t i o n s

[10] Talk by A. Edwards

[lq Contr. Paper # 749, J.J. Aubert e t a l . , (EMC), CERN-EP/82-48 9 2 1 H. Abramowicz e t a l . , (CDHS), PL 107 B (1981) 141

j13] Talk by P. Schmid

Contr. Paper # 712, Mu1 t i p 1 ic i t i e s of secondary hadrons produced i n vp and u p charged c u r r e n t i n t e r a c t i o n s , ABCMO C o l l a b o r a t i o n (BEBC-MA21 )

1141 Contr. Paper # 711, P. A l l e n e t a l . , Charge P r o p e r t i e s o f t h e hadronic system i n vp and ?p i n t e r a c t i o n s , MPI-PAE/Exp. E l . 103

1151 Contr. Paper # 612, Results on t h e i d e n t i f i c a t i o n o f protons produced i n vp i n t e r a c t i o n s i n BEBC equipped w i t h a TST, BBB EP R UCL C o l l a b o r a t i o n (BEBC-WA24) '-161

I_ Talk by D. Vignaud -

Contr. Paper # 543, Fragmentation o f t h e hadronic system i n a v, v D2 experiment;

comparison w i t h t h e LUND model , ABBPPST C o l l a b o r a t i o n (BEBC-WA25)

[ l j j Contr. Paper # 737, A. Vayaki e t a l . , Azimuthal asymmetry o f hadrons produced

i n ?-reactions, BBBCD-EP-IC-MORS-UCL C o l l a b o r a t i o n (BEBC-WA59) r181 Talk by G.A. Snow

Contr. Paper # 456, D. Zieminska e t a l . , Charged p a r t i c l e m u l t i p l i c i t y d i s t r i - b u t i o n s i n v n and vp charged c u r r e n t i n t e r a c t i o n s , IMSTT C o l l a b o r a t i o n

(FNAL 15' D2)

1191 Contr. Paper # 756, G.A. Snow e t al., Charmed baryon p r o d u c t i o n i n vD ⁺ u-AX

reactions, IMSTT C o l l a b o r a t i o n (FNAL 1 5 ' D2) r20J T. Sjostrand, LUTP-80-3 (LUND 1980)

1.21 [ H.C. Bal lagh e t a1 . , Observation o f muon i n n e r bremsstrahlung i n deep i n e l a s t i c n e u t r i n o s c a t t e r i n g Events, LBL-F-H-W-W C o l l a b o r a t i o n (E 546 1 5 ' ) , Contr. Paper 122) Contr. Paper # 704, H. Abramowicz e t a1 ., (CDHS), PL 109B (1982) 115

[ 2 3 \ Contr. Paper # 504, D.S. Baranov e t a1

.

i n vA and vA i n t e r a c t i o n s : p a r t I and p a r t 11, IHEP-Berlin C o l l a b o r a t i o n (SKAT) 1251 Contr. Paper # 747, M u l t i l e p t o n production by n e u t r i n o s i n Gargamelle a t

CERN-SPS energies, BCS-Collaboration

D . H a i d t C3-21

[26] Contr. Paper # 750, J.J. Aubert e t a1 . ^(EMC) , measurement o f I$ moments i n deep i n e l a s t i c muon proton s c a t t e r i n g

[27] Contr. Paper # 795, J. Gayler e t a1 . (EMC), Balance o f transverse momentum i n pN s c a t t e r i n g

1281 Contr. Paper # 748, J.J. Aubert e t a l . (EMC), Measurement o f t h e Q ~ , x and W 2 dependence o f s i n g l e hadron p r o d u c t i o n i n deep i n e l a s t i c muon s c a t t e r i n g , CERN-EP/82-47

[?9J Contr. Paper # 751, 3.5. Aubert e t a l . (EMC), P r e l i m i n a r y r e s u l t s i n hadron production i n 200 GeV p-copper and u-carbon i n t e r a c t i o n s

[30] Contr. Paper # 752, J.J. Aubert e t a l . (EMC), Muon p r o d u c t i o n o f heavy quarko- nium

[31] Contr. Paper # 773, J.H. Aubert e t a l . (EMC), Production o f open charm i n 250 GeV y+ i r o n i n t e r a c t i o n s

[32] Talk by K.H. Becks

K.H. Becks, New r e s u l t s on hadronic f i n a l s t a t e s from t h e EMC C o l l a b o r a t i o n , WU B 82-13 (Wuppertal p r e p r i n t ) ; F.W. Brasse, Hadronic f i n a l s t a t e s i n h i g h energy muon nucleon s c a t t e r i n g , r e c e n t r e s u l t s f r o m EMC, DESY 82-47

[33] G. Ingelman e t al., LUND p r e p r i n t LU TP 81-8 (1981) 13411 Talk by B. Roe

Contr. Paper #680, R.C. B a l l e t al., Prompt p r o d u c t i o n o f v by 400 GeV protons on tungsten, UM HE 82-15 and UM HE 82-16 and UM HE 82-21

[35] Talk by A. Bodek

A. Bodek e t a l . , A study o f t h e f o r y a r d p r o d u c t i o n o f charm s t a t e s and prompt muons i n 350 GeV p-Fe and 278 GeV a -Fe i n t e r a c t i o n s , UR-827 COO-3065-335 (1982) [36] P. A l l e n e t a l . , Nucl. Phys. (1981) 385

b7] D. Haidt, J e t s from hadron-, muon- and n e u t r i n o - i n t e r a c t i o n s i n comparison w i t h j e t s i n e'e--annihilation, Proc. 1981 I n t . Symposium BONN, p. 558