n PRODUCTION IN INCLUSIVE REACTIONS (,t s 155, 199, 310, 412, 425, 478, 660, 668, 755, 792, 900)

Presented by K. C. Moffeit· Stanford Linear Accelerator Center

Stanford, California

I will report on papers submitted to this conference on the inclusive reaction

a + b ~ rr-+

+ anything.

My talk will be divided into two parts. Firstly, I shall discuss some of the inter

esting but discrete points made in a few of the many excellent papers dealing with

rr-production at accelerator energies

data at 6 GeV to the results of Boyarski etal. 7 at 18 GeVas seen in Fig. S. The PT = 0.5 GeV ratio is nearer one than the larger PT results. 8The Mi1ano-Saclay col1aboration present the inclusive TI-p ~ TI + anything at 11.2 GeV/c in Fig. 6. Here one sees the effect of the leading TI- at x = 1 and

structure near x = 1, which becomes relatively more pronounced at smaller PT. The structure comes primarily from the 2-prong events, which reflects the TI- recoiling

against isobar production. Harari has pointed out that two-body production should

not be considered as part of the in~lu.ive study.9 lOThe paper presented by the ABBCCHLVW collaboration give

of the weighted

Tn distribution versus x for the 8 and l' GeV data. As seen in Fig. 7 they observe

the well-known seagull effect and find that increases in the beam and frag

mentation region with increasing energy.

The Approach to a Limiting Distribution llThe hypothesis of limiting fragmentation put forward by Beneckeet al. sug

gests that the spectra of low momentum particles become independent of the beam

energy as the beam energy becomes large. To test if this hypothesis holds the

single-particle distributions have been obtained for the quantity

F(PL ) = f E(dP:::/) dp/ +

in the laboratory frame for the inclusive n- production in various beam initiated

reactions. In Fig. 8 the data of the ABBCCHLVW collaborationl2 give F(P ) for theL

reaction n+p ~ TI- + (anything) at 8 and 16 GeV/c. They observe w~tnill errors no

energy dependence for PL < 0 GeV/c suggesting that limiting behavior is reached at

8 Gev/c. In contrast the data for n+p ~ n+ + anything do not show this same effect.

In Fig. 9, the higher energy data are lower by 20 to 50% at each point. A similar

energy dependence has been observed in other reaction (e.g., Reference 2). +

For pp ~ TI- + anything we can compare the data over a much larger energy interval with the results from the ISR. This is conveniently done in the variable x

since the ISR data are available in this form. In what follows we will take

Ixl ~ 0.2 to correspond to target (or beam) fragmentation. In Fig. 10 we see the data of Albrow et al. 13 for pp ~ ~+ + anything at

2 s = 1995 GeV and PT = O.~ GeV/c. For comparison the accelerator data of Allaby et al. 20 at s = 47 GeV2 is given. The TI+ distribution is equal, within the errors, for the two energies over the whole range of x. Thus It limiting fragmentation" or

"scaling" is a good description of the s-dependence of w+ production. However, the

data for pp ~ n- + (anything) shows a clear energy dependence from 12 GeV to ISR

energies as seen in Fig. 11. The figure is a compilation made by Sens18 using the 1Sdata of Bertin et al. and comparing to bubble chamber data. 16 ,l7 The point at

x = 0 is from the Saclay-Strasbourg collaboration and will be discussed later. The comparison of the transverse momentum distribution near x = 0.2 between accelerator

19energies and the highest ISR energy can be seen in the data of Albrow et al. in

Figs. 12 and 13. The PT data for the n+ distributions are similar at both energies,

with the higher energy data being slightly less steep than the lower energy data

(Fig. 12). However, the shape of the n- PTdistribution becomes much more rounded 2between the energies of 47 and 2800 Gev • The lower cross section at the higher

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energy for small PT is surprising. Future measurements at lower ISR energies and at

NAL will allow us to determine the energy dependence of the approach to a limiting

distribution in pp + n + anything. The hypothesis of limiting fra~entation, while suggested to ~e applicable at

s + ~, seems to' set in at surprisingly low energies J~ some reactions, while 21at higher energy for others. The discovery of Mueller has given a great deal of

quantitative understanding of the multiparticle spectra. He has found an optical

theorem analogy for single-pa~ticle spect~a. ~he familiar optical theorem relates

the total cross section for a + b + anything through unitarity to the imaginary part

of the forward ab elastic scattering amplitude, as indicated schematically by

Disc 11l\

This permits the construction of models of 0TOT which avoid detailed reference to

the many channels that constitute "anything." Likewise Mueller's theorem relates

the inclusive spectrum a + b + c + anything to the discontinuity in missing mass of

the forward acb elastic scattering amplitude so that, once again, one may build

models for the structure function without describing the individual channels which

make up "anything":

a ~ b

DiscJ:K a ! b c

Assuming that the unphysical three-body amplitude is dominated by the same Regge 12singularities as the physical three-body amplitude Chan, Hsue, Quigg, and wang find

F(PL'PT~S) = A(PL,PT2) + B(PL ,PT2)S-1/2

t t Pomeron Exchange degenerate meson a(O) = 1 trajectories a(O) ~ 0.5

In order to test this prediction,f (PL's) is given in Fig. 14 at PL = 0 versus

s-1/2. The structure function was obtained at P = 0 from the inclusive distribuL

tions integrated over transverse momentum. The data come from bubble chamber ex

periments 2 ,12,23-25 and are consistent with an s-1/2 dependence. The size of the

errors suggest that new experiments which can measure the structure function well

over a broad energy range will be worthwhile. As pointed out by Meyer and

Struczinski,26 the data are also consistent with approaching a limiting distribution

as exp(-b/IS). As can be seen in Fig. 15, they find that the reactions tend to pro

ject to two infinite energy limits.

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Using the duality hypothesis, Chan et al. 22 also suggest that when the quantum

numbers of the three-body system a + b + C are exotic a limiting distribution will be obtained at lower energies than if a + b + care nonexotic. Therefore, the reaction ~+p + n- + X which has exotic quantum numbers in abc (i.e., ~+p~+) should show less energy dependence than the reaction ~+P + n+ + X which has nonexotic quantum numbers. Indeed this behavior is observed in the data. In Fig. 14 the

nonexotic channel ~+p ~ n+ + X varies rapidly with s-1/2 while n+p + ~- + X remains

essentially constant.

Scaling at x = 0 Feynman27 has suggested that the structure function "scales l' at high energy.

That is, as s + 00, it becomes a function only of PT and the ratio x = PL*/Pmax*' where PL* is the c.m.s. longitudinal pion momentum and P * is the maximum c.m.s. max pion momentum.

+ +In Fig. 16 the structure function for n-p n- + anything is shown for the data

of LBL and Notre Dame. We see the cross section rise over 2 orders of magnitude,

reaching a peak at x = 0 followed by a behavior which reflects the influence of the projectile near x = 1. At x = 0 there is a strong energy dependence for the reaction n+p ~ n + (anything), ~25% increase between energies from 3.7 to 18.5 GeV/c. This

means scaling has not been reached for this reaction. However, the reaction

n p + n + anything shows little energy dependence. Exact scaling is also ruled

out but only measurements carried out at NAL will tell by how much.

The ISR data allows us to test the scaling prediction in the reaction

pp ~ ~-+ + anything. Figure 17 shows the comparison made by the Bonn-Hamburg

29Munchen co1laboration at 12 and 24 GeV/c to the ISR data of the SaClaY-Strasbourg31

32and the British-scandinavian collaborations. The cross sections at x = 0 for the 12 and 24 GeV data are obtained from bubble chamber data by using data for rapidities

in the c.m.s. less than 0.4 fitted to the expression

3 E d (j = ! ~ = 1. ~I exp(-Ay*2 )

3 n • 2 n * 2d P dy dPT dy dPT *

Y =0 thus yielding the cross section at x = O. Although there is some energy variation of the cross section, there is little variation in the shape of the PT distribution

between 12 and 1500 GeV/c (in contrast to the variations which were observed for

the fragmentation region). As seen in Fig. l7b the dependence of the n cross

section on energy is larger than that of the n+.

As data from many reactions at different energies have become available, the

approach to a scaling limit has become of interest. As we have seenl different beam

initiated reactions clearly have different behavior. Two papers submitted to this

conference have compiled the data available. They have looked for trends in the

data to understand the approximate scaling of one reaction at accelerator energies

and the lack of scaling in other reactions. In Fig. 18 we see the compilation of 6Ferbel. 30 Motivated by the ideas of Mueller concerning the approach to scaling

he plots the normalized cross sections at x = 0 integrated over P versusp-l/4. TheT straight lines are drawn to guide the eye but also suggest that the experimental

points from each reaction:

1. appear to fallon a straight line and

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2. all straight lines appear to extrapolate back to a unique point in the

limit of infinite energy.

Although, the data are consistent with a p-l/4 behavior (a somewhat surpr~s~ng result at such small laboratory momentum) other dependences cannot be ruled out.

Meyer and Struczinski26 find the data are also compatible with an's-I/2 behavior

(~pl/2) as is seen in Fig. 19. (Figures 18 and 19 are compatible within the errors which are given on Fig. 18; Meyer et ale do not give errors.)

The reason for the large error on the ISR point (Fig. 18) is to account for the

absence of measurements at small PT. The cross section for PT less than 0.2 GeV/c

is important to the integrated structure function and accounts for a large fraction

of the cross section at x = O. The accelerator data become flatter in PT for this region (see Fig. 17), however, we do not know the behavior for the high energy

(see Fig. 20).

By comparing the structure function at a particular PT one avoids the region

which has not been measured and can thereby use the experimental points to test the

s-dependence of the cross section. In Fig. 22 I have replotted the data of the 3lSaclay-Strasbourg collaboration shown in Fig. 21 and the data of the British

Scandinavian collaboration32 for two small and two large PT values together with

the data of Idschok et ale on a linear scale versus 5-1 / 4 (since no tables are

available for the data I extracted the points from Fig. 21 for the Saclay-Strasbourg

points). While the ISR data are consistent with no energy dependence, they are also 1consistent with an 5- / 4 behavior. We observe a larger energy dependence at large

PT. Thus scaling (by scaling I mean when the structure function is within say 5%

of its infinite energy value) seems to be reached for small PT at a lower energy

than for large PT.

References

IG. Alexander et al., '310.

2K• C. Moffeit et al., Phys. Rev. OS, 1603 (1972) and #412.

30 . Horn, Tel-Aviv preprint, TAUP-27l-72R.

4w. Struczinski et a1, 1668. 5H• Burfeindt et al., '660.

6A• H. Mueller, Phys. Rev. D2, 2963 (1970).

7Boyarski et al., contribution to the 1971 International Symposium on Electron and

Photon Interactions at High Energy, Cornell.

8p • Borzatta et al., '199.

9H• Harari, oral communication in parallel session on Deep Inelastic Scattering.

lOABBCCHLVW collaboration, private communication. See also Boesebeck et al., '167.

IIJ. Benecke, T. T. Chou, C. N. Yang, and E. Yen, Phys. Rev. 188, 2159 (1969).

l2J • V. Beaupre et al., Phys. Letters 37B, 432 (1971).13

M. G. Albrow et al., '792.

14L . G. Ratner et al., Phys. Rev. Letters 27, 68 (1971).

lSA. Bertin et al., Phys. Rev. Letters 38B~260 (1972). l6H. J. Muck et al., Phys. Letters 39B, ~ (1972). 17R• S. Panvini et al., Phys. Lette~38B, 55 (1972). l8J • C. Sens, Proceedings of the Four~nternationai Conference on High Energy

Collisions, Oxford, U.K., 5-7 April, 1972, ed. J. R. smith, (Rutherford High

Energy Laboratory, Chilton, Berks.), Vol. 1, p. 177.

19M• G. Albrow et al., 1792.

20J • v. Allaby et al., contribution to the Fourth International Conference on High Energy Collisions, Oxford, U.K. (1972).

2lA• H. Mueller, Phys. Rev. 02, 2963 (1970).

22Chan Hong-Mo, C. Hsue, C. Quigg, and Juinn-Ming Wang, Phys. Rev. Letters 26, 672

(1971). See also H.D.I. Abarbanel, Phys. Letters 34B, 69 (1971).

23M. Alston-Garnjost et al., Phys. Letters 39B, 402 (1972).

24w• o. Shepard et al., Phys. Rev. Letters ~ 1164 (1971), E. 28, 260 (1972). 250 . J. Crenne11 et al., Phys. Rev. Letters-;8, 643 (1972).

26H. Meyer and W. Struczinski, t425. -

27R . P. Feynrnan, Phys. Rev. Letters ~, 1415 (1969); R. P. Feynman, The Behavior of Hadron Collisions at Extreme Energies, California Institute of Technology

report (1969); see also High Energy Collisions (Gordon and Breach, New York,

1969), p. 237.

28M• A1ston-Garnjost, Proceedings of the International Conference on Inclusive

Reactions held at the University of California, Davis (1972), p. 182.

29u. Idschok et al., #755. 30T . Ferbel, i151.

31M. Banner et al., *478.

32B• Alper et al., #900. The points plotted in Fig. 22a,b were obtained from

E. Lillethun, private communication.

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•••••••• • ••

100

50

. .'. 20 . ~"--""............

I .... , 10 • I " •

I / "

•".

5 • I , tI \

I \+ I \

2 / \ It II

)( I u.. I

I.50 I I I I

t I

I J

I I

.20

.10 I ------ yp I

,I .05 , yd This experiment+

.02

.01 -1 -.5 o .5

X

Fig. 1. Structure function

F(x) 1 lCD 1r 0

versus x for yd ~ n + ••• at 7.5 GeV (Ref. 1). The dotted line is an approx

imation to F(x) from the (yp,n-) data at 9.3 GeV of Ref. 2.

-292

10

9

8

7

6 a: (.)

5

4

3

2

1

0 ·1

Fig. 2.

0 x

The ratio CR

1

= Fyn,ff-(X)/Fyp,n-(X) (Ref. 1).

-293

o 2 -1 o 2

Fig. 3. Structure functions

2

fPTmaX

E* d 20 2 H(y) = -----. ------2 d PTo P dxdPTmax

for ~+ and n- averaged over the following Ey

ranges (from top to bottom): 5.0

< E < 6.3 GeV, 3.6 < E < 5.0 GeV, 2.6 < E < 3.6 GeV, 2.1 < E < 2.6 GeV,y y y y1.65 < E < 2.1 GeV (Ref. 4).y

-294

-1

ky = 6 GeV preliminary

x Pi :.3

3 0 Pl. =.5

0 P.i :.7

l:J. Pi = 1.

X I ~

t 0. :>

-- 2 ! I

X + ~ ~ t a. ~ I ~4 ~

~

f t 2 ! 2 I 2

i

2

I

.1 .2 .3 .4 .5 .6 .7 .8 .9 X = pcm/pcm

II max

Fig. 4. The ratio of the invariant cross section for the reactions yp + ~+x and

yp + ~-x is plotted versus x with the transverse momentum PT as a parameter (Ref. 5).

-295

2. rI o.1.8~ n+

1.6 f1.4~

1.2 f I y

f2 f

1.1---------- - - - - ----- -- -----

.8 I ~ i>

(1) .61C> x PJ. =.5 (f)

I I I J I IlLJ .1 .2 .3 .4 .5 .6 .7 .80 ........ X " r I r~ (!)

2.4~ Q) b. rr '-" 2.2 .... U 2.f «

.-

I --I

I f ~ ~ 1.81(/) t16~ Y 0

1.4~+J

0 0:: 1.2

1.1--------------------

.8 i .6

.4 preliminary

.2~

I I I

.1 .2 .3 .4 .5 .6 .7 .8 em/ emX=PI' Pmax

Fig. Sea). The ratio of the invariant cross sections for yp ~ ~+x at 6 and 18 GeV

is plotted versus x for a transverse momentum of 0.5 and 1.0 GeV/c.

Fi9- S(b). Same as (a) but for yp ~ ~-X (Ref. 5).

-296

TT p---+lT + anything

o -integrat ed over all P~ &l p~ c: 0.16 GeV

2

o p~ G 0.10 GeV) 6) P: ~ 0.04 G~V7

N ...

0.

-f

a. 10 )(

101+-- --......--..;,,;, ~:::...:::::.. ')..... :.;.;..::~::::::.:.:.\ .... ::::..:::::...>:_:::;~:};-;-?:-::"";";':':';";':';";";" .~.'-'';'";'';'''';'''''':':':'';'':'~'''''':'':':':';-'';';'';'~''''' -1. -.8 -.6 -.4 -.2 0 .2 .4 .6 .8 1.

2 c/'\.s X::~

'!I

Fig. 6. The structure function for n-p + ~-x at 11.2 GeV/c integrated over differ2ent ranges of PT (Ref. 8).

-297

0.6

~ ~ ~0.4

Al&J

Q......

V 0.2

Q..1

IA..--......- ......- ......--r--......- .......----r-........--.,-.....,

I iD co 1.2- I f I

-I

Fig. 7. Upper plot: average E-weighted PT versus x at Rand 16 GeV/c. Some repre

sentative error bars are given only. Lower plot: ratio of averaged wei~hted

PT at 16 and 8 GeV/c (Ref. 10).

-298

",+p.1r-+ onythlno ..._8 G.VIc 4 _16 GeV/c

10 -~t!!!+t+L!1~~~~~~+!m:r:I:l::t

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:,:' I:' :':! -r-lil:!!I;

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: ~i .:.~ I

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I ~; I!' I III!! ii t. j! I ii, ~ Ii: !: i:; i1 _c ,'1

'0 'i

! ~ i.i.,I' :1': ii:, i· "1'1";": iil I I: iii! " .- ",!!i ,I I l:

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tLONG. MOM. OF 7T . P LAB GeV/cII

Fig. 8. Structure function for P < 0 integrated over transverse momentum forL n+p ~ n-X at 8 and 16 GeV/c (Ref. 12).

-299

--- 8 GeV/c .,,+P.. ".++ anything _16 GeV/e4 10

!t;. \'

i',. , ~ .'i .,.. , i ~!!.~ ~I ~!~• .'. i iT : i :: iIi ::! .,: ~ ~ : ~ ~~ i: I .

103 li)W l,!l i1i ':i!~ :

I" ~ if il ;.! j- !'11 j='

, i :i I I, :I!) !I ! !.1 ~ li:ll 11 ~ I~ I';

til

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:,' '" I I

i II I; ,';:1 :!,Il

~ :1, !-~ J:lI11: '.l i I ,! i : ! :Ii! i: ! ,. .1' I ~ i ! j, !

;i:: I;Ii i I.J: 'I'! II: li.I!:i l·' ,~:,' !. 1- ]-1 jLj i" -I T,· -1-,'1 . -I j. t-- i-.-I," Hi' rliLO . .' I~ Ii :i I ~ i !-.;. . ~ : : : i; " ... I

I ~~~m. :'~l~. r-·~ J#ll:~ 1lllll....ttl.r~d;n~m~llgll::I:-

-~4 -02 0 + LAB

LONG. MOM. OF .,,-. P GeV/cII

Fig. 9~ Str~cture function for P~ < 0 integrated over transverse momentum for

n p + n X at 8 and 16 GeV/c (Ref. 12).

-300

10--------------------.

5 = 1995 (GeV)2 qT= 0.8 GeV/c

Allrow et al. o 1t+

lcf

~ It+ Ratner et 01.

Allaby et al. s =47 (GeV)2

10-3L....-__---l...- ---l o 0.2 OA 0.6 0.8 1.0

X =1.9.b.vs Fig. 10. Longitudinal momentum spectra for pp ~ ~+ + anything as a function of

~ 13 x = 2PL/~s for a constant value of P = 0.8 GeV/c. Data of Albrow et ale 14 z and Ratner et al. Curve is appr~~imate behav~ of accelerator data of

20Allaby et al.

-301

j SOO..11OO,15OOGeYIc ~VI100 • 225 GeV/C} BOl.fi • 500 GeVic BERTIN ET AL. • 1100 GeVic * 1500 GeVic

- 12 GeVlC} MOCK ET AL. JII::J 24 GeV/c

- - - 28.5 GeVic PANV1NI ET AL. V BERnNETAL. (ee REMOVED)

, P =0.4 GeVlcT

01

o x

Fig. 11. Invariant cross section versus x = PL/P for pp ~ ~- + anything at max� P = 0.2, 0.4, and 0.8 GeV/c (Refs. 15-18).�T

-30l-

100.....---~---~--------r-------~

p+p-- IT++ •••• AllABY ET Al.�

-E = 53 GeV 6 D RATNER ET AL.�I cm

10

!

~ i, ~ C) ! ..a E 10

t, if

~ x=0.18 w

!,t

10 x= 0.21

1.0~--__-~---_.......-----------o 0.5 to 1.S

rt(GeV/c)

Pig. 12. Invariant cross section for pp + ~+ + .•. at a total center of mass energy

of 53 GeV and x = 0.18, 0.21, and 0.25 (data of Albrow et a1. 19 ). Also in-14dicated are data points from Ratner et al. at 31 GeV (6) and 45 GeV (0) at

x = 0.2; the solid line represents interpolated accelerator data at 19.2 GeV/c 20

from Al1aby et a1.

-303-

10r-----:::"""I"""'''''t'''"------,...------ ----- ___

p ... p-- IT + .... E =53GeV cm

ALlABY ET AL.

BERTIN ET Al. 10

x: 0.18

10

x =0.21

x :0.25

O.lL....- ----L. ...a.- -----'

0.5 to 1.5° P (GeV/c)T

Fig. 13. Invariant cross section for pp ~ ~- + ••• at IS = 53 GeV and x = 0.18, I90.21, and 0.25 (data of Aibrow et a1. ). Also indicated are data points from

ISBertin et al. at 53 GeV at x = 0.19; the solid line represents interpolated accelerator data at 19.2 GeV/c from Allaby et al. 20

-304-

Na.-I

"

0.3 I + +1T p--1T + ... LBL-GroupA ABBCCHW BNL

b ~-t ~ N

-0 Q..-"a

UJ 8 '---.........0 0.2

8- ...,.. 0

b" .. 0

1T-P~7T-+···

Notre Dame Erwin et at

II

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~ 0.1 SLAC-LBL-Tufts

0.-...., ._t----- 1T+p-. 7T -+· ..~ LBL-Group A

Notre Dame� ABBCCHW�

o

Fig. 14. The integrated structure function evaluated at P = 0 versus 8-1/ 2 • DataL +

from Refs. 2, 12, 23-25. In the normalization crTOT(oo) was used: ~-p = 23.4 rob, yp = 99 llb.

-305-

+ +•� np-t"'n p p -('"- n+

IT� • ~ yp~ n+1.0 F(y,s)1 y =0 + -6 tot lob 0 np~ n 0� pp~.. n-"V� yp4,.. re D,.� rCp-f.... IT -

0.1

I .~ (GeV- ) 'IS

o ..1 .2 .3 .1.. .5 Fig. 15. The energy dependence of the invariant cross section for inclusive n-+

production and various incident particles at Ylab = 0, nF(y'S)/OTOT (Ref. 26).

-306-

o

A •

0.1 7T-p--7T- l'e A~·~

"-"rl'# ~ + -~i

P Distribution at 90° y

x SOOJ1100J1S00GeV/c "0tJl ("')-00. SaclayIS trasbourg W + 1500GeV/c Brit.lScand.

10 • 24 GeV/c • 12 GeV/c

to

!!+

+. + 0.1

t i

t o.

0.0 0.2 0.4 0.6 . 0.8 1.0 1.2 1.4 ~ GeVJc

Fig. 17(a). PTdistributions a~ 9a~ for u+ production at the ISR (Ref. 29).

-308-

p Distribution at 900 T

"'0-0°l~ x 500..1100..1500GeV/cUJ Saclay/Strasbourg

10 + lS00GeV/c Brit.lScand. • 24 GeVJc • 12 GeV/c

1.0-

Fig. 17(b). P distributions at 90° for ~- production at the ISR (Ref. 29).T

-309-

0.8 c =0.76 ±0.05

o .. 0.6 c..J

---

• •

I

0.3

G-L F(y,s)1 v =0 tot JCMS o pp ... r( • pp .... n+

+� -o n.p~ IT +� +• np+n.. [j. rep+ rf•

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~ o 0.1

o o

1 . ..jS (GeV~l)

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a 0.1 0.2 Q3 0.4 0.5 Fig.� 19. The energy dependence of the invariant cross section for inclusive ~± production and

various incident particles at y = 0, F(y ,s)!oTOT is shown (Ref-. 26).

ISR Saclay - Strasbouro British-Scandinavian

o� 0.2 1.2 ~ (GeV/c)T

Fig. 20. Region of� the P distribution at x = 0 which has not been measured at ISRT� energies.�

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100.----------~'I"""-...-~-'I""--.-.,~.._ ....._r_......._'T.....,-r_.,..~_r_:l Saclay- Strasbourg Collaboration

P+P~7T+ +... I · P+p.....7T-+··· at X = 0� at X =0

+

t .. 52.7� + .52.7

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Fig. 21. Invariant cross sections E(d 3cr/dp3 ) at x = 0 as a function of the pion transverse momentum PT at different IS values. The errors shown are statisti-cal. To compare cross sections from one energy to the other one has to con-

sider a 5% systematic error of the luminosity measurement (Ref. 31).

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Fig.� 22(a). The structure function for pp ~ n+ X at x -~ 0 for selected PT values plotted versus s-1/4. The data ·for the Saclay-Strasbourg collaboration31 have

been taken from Fig. 21 (uncertainties of the order of 5% are introduced in

such a transfer which have not been added to the errors shown).

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Fig.� 22(b). The structure function for pp + ~- X at x = 0 for selected PT values plotted versus 5-1 / 4 • The data for the Saclay-Strasbourg collaboration31 have

been ~aken from Fig. 21 (uncertainties of the order of 5% are introduced in

such a transfer which have not been added to the errors shown).