* Fermi National Accelerator Laboratory FERMILAB-Pub-78/96-ExP 7180.288

(Submitted to Phys. Rev. Lett. )

EVIDENCE FOR THE T” AND A SEARCH FOR NEW NARROW RESONANCES

K. Ueno, B. C. Brown, C. N. Brown, W. R. Innes, R. D. Kephart, and T. Yamanouchi

Fermi National Accelerator Laboratory, Batavia, Illinois 60510

and

S. W. Herb, D. C. Horn, L. M. Lederman, H. D. Snyder, and J. K. Yoh

Columbia University, New York, New York 10027

and

R. J. Fisk, A. S. Ito, H. Jbstlein, and D. M. Kaplan State University of New York, Stony Brook, New York 11794

December i9 78

0 OporWd by Unlvwrl~i~r Reemrch Aaroclotlon Inc. under conbac1 with the Unlled States De~mtmeni of Energy

EVIDENCE FOR THET" AND

A SEARCH FOR NEW NARROW RESONANCES

K. Ueno, B. C. Brown, C. N. Brown, W. R. Innes, R. D. Kephart, and T. Yamanouchi

Fermi National Accelerator Laboratory Batavia, Illinois 60510

and

S. W. IKi.e;: s",;Ze.,H&q,(aad LJ.. MK.. yzlrman,

Columbia University New York, New York 10027

and

R. J. Fisk,@) and i: i: ::;ia:jdjf"Stleint

State University of New York Stony Brook, New York 11794

ABSTRACT

The production of the T family in proton-nucleus

collisions is clarified by a six-fold increase in sta-

tistics. Constraining T, T' masses to those observed at

DORIS we fi2d the statistical significance of the T" to

be 11 a. The dependence of T production on p,, y, and s

is presented. Limits for other resonance production in

the mass range 4-18 GeV are determined.

-2-

~a report on further details of Upsilon’r’ production in

proton-nucleus collisions at Fermilab. In addition to. data pub-

lished previously,‘-’ we present here results from data taken in

1978. Our entire data sample can be divided into four subsets: I.

published data with 400 GeV incident proton energy and 1200 f(or

T’) events, mass resolution (&l/M) of 2.21 (rms)“‘; II. ZOO/300

GeV, 500 T’s, AM/H = 2.29 ; III. 400 GeV, 7000 T’S, AM/M - 2.2%;

Iv. 400 GeV, 500 T’s, &4/M = 1.7%. Except where noted all results

hereafter are from 400 GeV data. The resolution improvement in

data set IV was achieved by lowering the intensity of protons so

that a multiwire proportional chamber could be installed and

operated halfway between the target and the analysis megnet.

Table I lists apparatus and software efficiencies and cor-

rections made to the data. Cross sections per Pt nucleus were

oonverted to cross section per nucleon by dividing by St = 195. An

isotropic decay angle distribution was assumed for resonances while

1 + cos’e(Gottfried-Jackson frame) was assumed for the continuum.

All the data from sets I, III, and IV between masses of 7.3 and

12.9 GeV were fit simultaneously. A linear exponential form was

assumed for the continuum. This form fits the continuum well in

this mass range.

The continuum shape, resonance mass separations, and relative

cross sections were the same for all data sets but mass resolution,

acceptance, normalization, and mass scale were particular to each

set. Assuming three resonances and letting dll parameters vary we

obtain the first coluti in Table II.c This fit yields the

-3-

spacing ml, - mT = 0.57 i 0.03 GeV. If we constrain mT, - 9 to the

0.555 t 0.011 GeV value measured at DDRIS',ve obtain the result in

the second column of Table II. In this case assuming two resonances

instead of three increases x2 by 125 indicating a significance of

11 ~8 for the T'. We consider this convincing evidence foe a third

resonance. Data set III with continuum subtracted is plotted in

Pig. 1 and compared with the fit constrained by the DDRIS measure-

ments. Table III gives the correlation matrices for the fits in

Table II.

These results combined with the observation of T and T* 6t

DORIS"' strongly support the interpretation that the f, T' and T'

are the n3S1 ti states (n = 1,2,3) of a new heavy quark with charge

l/3 ('bottom'). Successful fitting of both J& and T families with

6 common potential,'d" 6UCCe66fUl prediction Of -, 3 Stat66," 4-

- mT*"', l'- ,(Tand T)' * nr and B,,J"? all reinforce this inter-

pretation.

In Pig. 2 we show the energy dependence of T production'* and

-pare it to that for $ production.'* We 6ee that they are

similar.

Pigure 3a shows the Pt dependence of theT cros6 section (con-

tinuum subtracted). The Curve show6 a fit to the continuum in

idjacent mas6 bins. We see a significant difference particularly

at the highest values of pt. ' Pt 'T i6 1.44 t 0.04 GeV while

< pt > of the continuum is 1.20 5 0.02 GeV. ?igure 3b 6hOWS the y

dependence of the T (also continuum subtracted) and a curve showing

the expected continuum .khavior based on interpolation from the

-4-

surrounding continuum via the parton annihilation model. we see

that in contrast to the continuum distribution the T distribution

La smetric about y = 0. d(4,(d*ddm dy)]/dyly5S is 0.1 f 0.2 for

the T VS. 0.5 t 0.1 for the continuum. This,together with the pt

dependence, the small ratio of T to continuum see" in our 200 GeV

data (at y - O-4),' and the large-ratio of T to COntinUum seen at

the ISR" m - 60 GeV), suggests that the T production mechanism

differs from that of the continuum.

The observed mass spectrum (Pig. la). combined with knowledge

of the mass resolution (confirmed by the observed resolution of J/e,*'

ti T) allows us to determine upper limits for B,,,, &/dy for narrow

resonances (independent of origin) in the mass range 4-18 GeV in

proton-nucleus collisions. These are presented in Fig. 4b. Assum-

img resonance production is approximately proportional to the

continuum and assuming a resonance production model, we can set

limit8 on the masses of new quarkonium systems. Figure Ib~compares

the 95% confidence level upper limit for B lrlr a/au

[reaonaace)//du/dm dy (continuum) with the predictions'of two pro-

doctfon mcdels."~l~ Following J. Ellis et al.," we find m l/3 ' l5 GeV and m2,3 P 16.5 GeV for charge l/3 and charge 2/3 quarks

respactively. Following R. Cahn and S. Ellis" we find m l/3 > 15

GeV and m2,3 > 17.5 GeV.

In sumry, further data on T production in proton-nucleus

oolliaions and the observation of T' at DORIS have increased the

l ignificance of the T' to 11~ and supplied more evidence for the

quarkonium interpretation of the T family. Assuming that only one

-5-

additional narrow resonance above the T' contributes to our masg

spectrum, we determine the T‘ mass to be 10.41 t -05 GeV. Differ-

ences in the dynamics of T and continuum production point to

differing production mechanisms. Other quarkonium families with

comparable resonance/continuum signals are unlikely in the mass

range 4-14 GeV. A quarkonium family based on a charge 2/3 quark is

unlikely below 16.5 GeV.

We wish to thank the staffs of our respective institutions,

particularly the accelerator staff at Fermilab. This work was

funded in part by grants from the National Science Foundation and

the tJ. S. Department of Energy.

RKFRRKNCES

(a) Present address: Riverside Research, 80 West 3rd Ave.,

New York, New York.

fb'Present address: .

Gallaudet College, Washington, DC 20002.

87'Present address: Fermi National Accelerator Laboratory,

Batavia, Illinois 60510.

WI Present address: Nevis Laboratories, Columbia University

Irvington, New York 10533.

'8. Y. Herb et al., Phys. Rev. Lett. go, 252 (1977).

'Y. R. Innes et al., Phys. Rev. L&t. 2, 1240 (1977).

'D. N. Kaplan et al., Phys. Rev. Lett. a, 435 (1978).

l .7. K. Yoh et al., Phys. Rev. Lett. 4l, 684 (1978).

‘The normalization of the data presented here differs from that

of our previous publications. The primary cause of this change

uas the discovery that the Pt target used in data set I bad

partially melted. Other causes are changes in the decay angle

and pt distributions assumed in calculating the acceptance and

the inclusion of nucleon-motion and radiative corrections.

‘fhe mass scales in these fits were adjusted to yield the

#IRIS result m = 9.46 GeV. If this is not done our result is mT

=-9.45 t 0.05 GeV. The error is entirely systematic and arises

from uncertainties in the magnetic field measurement and in

knouladge of the energy loss in the hadcon absorber.

l C. W. Darden, et al., Phys. L&t. 78B. 364 (1978). -

-7-

.7. K. Bienlein et al., Phys. Lett. 788, 360 (1978). -

aC. W. Darden et al., Phys. Lett. 768, 246 (1978) and C. Berger l f -

al., Phys. Lett. z, 243 (1978).

l C. Quigg and J. L. Rosner, Phys. Lett. 718, 153 (1977). -

'9. Thackec, C. Quigg and J. L. Roenec, Phys. Rev. D la, 287

(1978).

“R. Eichten and K. Gottfried, Phys. Lett. 668, 286 (1977). -

I*R. N. Cahn and S. D. Xllis, Phys. Rev. D16, 1484 (1977). -

'SL. Camilleri, J. Ranelli and Ii. Newman, XIX International

aference on Bigh Energy Physics, Tokyo (1978).

I-R. C. Broun et al., Fermilab-Pub-77/54-Ksp (1977), unpublished.

K. J. Anderson et al., Phys. Rev. Lett. 36, 237 (1976).

Tu. H. Antipov et al., Phys. Lett. SOB, 309 (1976). -

0. Becker et al., private communication as reported by Anderson

et al.

J. 8. Cobb et al., Phys. Lett. 6+, 101 (1977).

?. W. Busser et al., Phys. Lett. 37, 574 (1976).

s*J. Kllis et al., Nucl. Phys. B131, 285 (1977).

TABLE f

EFFICIENCIES, CORRECTIONS, AND ACCEPTANCE

Rfficiencies

Trigger 0.92 t 0.04

DIta compression 0.96 t 0.01

Reconstruction 0.88 t 0.03

Targeting 0.97 f0.03

Caabined 0.76 iO.06

Qrrections to cross section (multiplicative, at the T 1~66)

Nucleon Motion 0.80 f 0.10

Radiative (resonance) 1.10

Radiative (continuum) 1.03

A-dependence 1.00 t 0.07(a)

Acceptance (-.3 4 y < .3L

1 + cos2~(continuum) 0.0059t0.0003

Isotropic (resonance) 0.0065i0.0003

Overall normalisation uncertainty f0.15

(a)Tbis represents the uncertainty in the calculation Of the per 'nucleon' cross sections from the per nucleus cross sectio"s.

-9-

TABLE II

Resonance Fits(a'

Parameter Number $.-II+ Free1 nLf.-~-.555*.011 Units'

Continuum Parameters (d2cr/dmdyl y=. = Aemb(“-~‘)

AI 1 0.262%004(?.04)

AI11 2 2.003 (b’

AIv 3 i.004 (b’

b 4 0.954+.006(.015' Resonance Parameters

=+I 9.46(fixed)

Q.& (Cl 5 1.15 f.03

B&/W po T 0.30 t.Ol(t.05'

4-r 6 O-574+.027

B&/dy\,, T./T 7 0.32 2.03

4'-PLF 8 0.97 t-05

-VW T'R yxo 9 0.13 A.029 C-n Parameters

bm/m(rms)I 0.022 fired

Am/m(rms)III 0.022 fixed

ArP/m(rms) IV 10 0.020~.002

m factor I 11 0.99a+.oo2

m factor III 12 1.001~.001

m factor IV 13 1.0001?.002

0.022 fixed

0.022 fixed

0.020~.002

0.997t.002

l.OO1t.OO1

1.000f.002

163/156

-

X2/D, 163/155

"'Where significant, systematic errors are given in parentheses.

(b'Since data sets III and IV have not been carefully normalized the precise values of these parameters are irrelevant.

(C) T$is parameter is Bw do/dy(ypo for T production divided by d o/dmdy)yO, m"pr for the continuum.

0.262'.004(f.04) pb/GeV

*.003(b) -

2.004(b) .

0.953k.006(?.015)GeV-1

9.46(f ixed) GM

1.14 2.03 GeV

0.30'.01(+.05), pb

0.558~.011 GCV

0.31 f-03

0.95 t-03 GeV

0.15 2.017

-iO-

TABLE XIII')

Correlation Natr~ces

‘r’-a Free

1 2 3 4 5 6 7 8 9 10 11 12

2 .452

3 .250 .359

4 -.481 -.703 -.345

5 -.293 -.421 -.270 -306

6 -368 -518 .220 -.408 -.207

7 .a57 1077 -049 -.079 -.677 -.118

a .164 .263 -156 -.190 -.540 .140 .613

9 -.500 -.733 -.347 .654 -399 -.517 -.214 -.334

10 -.098 -.156 -.034 .122 -218 -054 -.194 -.290 .145

11 -057 -074 -038 -.021 .237 .072 -.232 -.234 -006 -092

12 -183 -302 -096 -.215 .216 .222 -.381 -.212 -.256 -.066 .146

13 -040 -102 -109 -.040 -016 -.063 -.054 .072 -.124 -.161 -011 -111

(cont'd)

TABLE XIX

Correlation Matrices (cont'd)

I

= 0.555 f .Oll

1 2 3 4 5 6 7 8 9 10 11 12

2 .476

3 -268 .418'

4 -.508 -.727 -.420

5 -.406 -.5:7 -.345 .446

6.-.060 -.074 -.048 .I09 .314

7 -.239 -.325 -.191 -327 -.222 -.279

8 -.322 -.420 -.244 .469 .264 -.031 .251

9 .071 -.004 .OOO -.033 -.369 -.328 .095 .032

10 -.055 -.036 -.035 -039 -149 .108 -.071 .021 -.137

11 -092 -.045 -.030 -.056 .028 .088 -032 -181 -053 -.058

12 .072 .177 .071 -.087 -213 .164 -.339 -.166 -.328 .123 -.013

13 -. 020 -.015 .lll -.Oll .120 .059 -.105 -.032 -.130 -044 .019 .126

(a'Parameter numbers as defined in Table II.

?IGURR CWTIURS

Iig. 1: nasa spectrum in the T region with continuum subtracted

(troa data set III). The curve is the fit described in the

second column of Table II.

rig. 2: s dependence of T and $I production. The T date are from

this experiment and Ref: 13. The J/J, data are fros Ref.

14.

tig. 3: (a) pt dependence of T production (continuum subtracted).

The curve shows the pt dependence of the adjacent con-

tinuum (the continuum pt spectrum is independent of mass

in this m55s range).

(b) y dependence of T production (COntinuum subtracted).

The curve shobs the continuuum y dependence based on

interpolation from the adjacent continuum with a parton

annihilation model.

Ng. 4: (a) Mass spectrum. The 4-6 GsV region is from data set

VW. The b-20 GeV region is from data sets (1)+(X11).

The curve shows the mass resolution.

(b) Upper limits (958 CL) on B,,,, dddy)y10 for new reson-

snce production.

(Cl Upper limits (958 CL) on the ratio of resonance to

continuum production. The dotted curves are the predic-

tions calculated with the model of J. Ellis et al., (Ref.

15). The dashed ~curves are the predictions calculated

with the model of R. Cahn and 8. Ellis (Ref. 12).

;=: E z c ‘F z 0 I

$i P b

2

I I I I

Q7-

h 0.6

t

I I I I 1 I

8 9 lo II mass (GeV)

- i=$ 1-;3’

ai5 %

4iii (3”

u Z&=

,+ g lo””

-0 R

‘A -37

Y 10 b

‘0

ai! (

-M-

I I I I ,p N-T+T’+T” %f’ -

0 This Exp. - i

J&J-“ 5

(ref. 13)- +j 0 Manelli d2 z A Newman _ 0 Camilleri . “E

s

:pN-JJ/J,(ref.l4) X ~Becker l Antipoy 9 A Anderson l &cwn

: -p_p--J/$(ref.14) i

b4 BGsser : l Cobb ;

0 k

x-

7 ,634 .b u

a? I I I I 1

0.1 0.2 03 0.4 a5 m/Y

ligure 2

m = 9.1- IO.6 GeV

p+ (GeV)

1 ‘I.- m=9.1-10.6 feV b s I * 9 I * * ” ‘-3-2-J CkJ234.!5

Y

lrigure 3

$1 r----IA

;:‘r--- ------ - -.-.... -- 1 --j=.-J-.r- -=... 1 .-I , 1 1 /

J

---I/ “1 I # 4 * a, t3ev7 2G