SLAC-PUB-6920

July 1995

PRODUCTION OF x+, K+, p, Ko md A“ IN

HADRONIC 2° DECAYS*

The SLD CoUaboration”*

Stanford Linear Accderator Center

Stanford University, Stanford, CA 94309

ABSTUCT

We have measured production rates and spectra of T*, K*, p/~, Ko and AO/~O

in fight- and heavy-flavor hadronic 2° decays and for particles and antiparticles sepa-

ratdy in quark jets. The SLD Cherenkov fig baging Detector was used to identify

charged hadrons. Samples enriched in fight (uds) and b events were tagged using im- -

pact parameters of charged tracks, and a sample enriched in quark (over antiquark) jets

was tagged using the electron beam poltiation. We observe a de= flavor dependence

in production rates and spectrum shapes, but ody a smd effect in f =b(l/zP) peak

positions. Dfierences between baryon and mtibaryon spectra in quark jets offer tiect

cobation that faster particles are more Uely to contain the titid quark.

Contributed to the Intern3tion31 Europhysics Conference on High Energ) Physics(HEP 95), Brussels, Belgiwm, July 27 - August 2, 1995

‘This work w= supported by Department of Energy contracts: D& FG02-91ER40676 (BL),

DEFG03-92ER40701 (CIT), D& FG03-91ER40618 (UCSB), DBFG03-92ER40689 (UCSC)) DE-

FG03-93ER40788 (CSU), DBFG02-91ER40672 (Colorado), DGFG02-91ER40677 (Illinois), DB

AC03-76SFOO098 (LBL), DLFG02-92ER40715 (M~sachusetts), DB.4C02-76ER03069 (lfIT)

DEFGO&85ER40224 (Oregon), D& AC03-76SFO0515 (SLAC), DGFG05-91ER40627 (Tenn=ee),

D~AC02-76ERO0881 (Wisconsin), D& FG02-92ER40704 (Yale); National Science Foundation grants:

PHY-91-13428 (UCSC), PHY-89-21320 (Columbia), P~-92-04239 (Cincinnati), PHY-8&17930

(Rutgers), PHY-8&19316 (Vanderbilt), PHY-92-03212 (W=hington); the UK Science and Enginwrbg

&arch Council (Brunei and WL); the Istituto N=ionale di Fisica Nucleare of Italy (Bologna,

Ferrara, Fr=cati, Pisa, Padova, Perugia); and the Japan-US Cooperative -arch Project on High

Energy Physi~ (Nagoya, Tohoku).

,

1 Introduction

The production of find state hadrons from ititid hard partons, e.g. the quark and

antiquark in e+e– - 2° + q~, is currently bdeved to proceed in three stages. The

fist stage hvolves the radiation of ~uons from the primary quark and antiquark, which

in turn radiate ~uons or spbt into q~ pairs untfl their titudty approaches the hadron

mass scale. Such a ‘parton showerm is cdcdable in perturbative QCD, for example in

the Modified Leading Logarithm Approximation [1]. The next stage, in wfich these soft

partons turn into ‘primary” hadrons, is not understood quantitatively, although several

hadronization modek exist. The ansatz of Local Parton-Hadron Dufity (LPHD) [1],

namely that the distribution for a given hadron species is directly proportional to the

parton distribution at some appropriate virtu~ty, dews the prediction of the shapes

of primary hadron momentum spectra, and of the energy- and mass-dependences of

their peaks.

The third stage, in which unstable primary hadrons decay into bd state hadrons,

complicates the interpretation of inclusive measurements. It is desirable to remove the

effects of these decays when comparing with the predictions of QCD+ LPHD. Addi-

tiond comp~cations arise in jets initiated by heavy quarks in which the leading heavy

hadrons carry a large fraction of the beam energy, restricting that avdable

primary particles, and then decay into a number of secondary particles.

Measurements of the production rates and spectra of identified particles

to other

are use-

M for constraining models and testing the predictions of QCD+ LPHD. Several such

measurements have been reported in e+e- anfiation and QCD+LPHD has been

successfd in describing the shape and energy dependence of inclusive momentum spec-

tra as we~ as those of identfied charged and neutral hadrons [2]. At a given CM

energy W, the spectrum for identified pions peaks at a higher due of f = k(W/2p),

where p is particle momentum, than the spectra of tigher mass particle types; however

tittle

SET

mass dependence is observed between these other species. The

hadronization model to correct for the effect of primary hadron

2

use of the JET-

decays h= been

.

shown [3] to introduce a mass dependence; direct observation of this effect is desirable.

Previous measurements have used samples of jets initiated by equal numbers of pr-

imary quarks and antiquarks. Comparison of the spectrum of a given particle with that

of its antiparticle in a pure sample of quark jets wodd provide additiond information

on the hadronization process. Baryons are particdarly usefd for this as a baryon can

contain a primary quark but an antibaryon cannot.

h this paper we present an analysis of% *, K*, p/F, Ko, and AO/~o production in

hadronic 2° decays co~ected by the SLC Large Detector (SLD). The analysis is based

upon the approximatdy 150,000 hadronic events obtained in ms of the SLAC Linear

CoMder (SLC) between 1993 and 1995. We measure production rates and momentum

spectra in a ‘~obd~ sample of d hadronic events and &o in high-purity samples of

‘fight” (Z” ~ uti, d~, SZ) and ‘b)’ (Z” + b~) events. The tight sample is largely free

from effects of heavy quark production and decay, but contains decay products of other

unstable primary hadrons. In addition we compare the baryon (p and A) spectra with

those of their antiparticles in a high-purity sample of quark jets, selected using the large

production =ymmetry in polar an~e induced by the SLC dectron beam polarization.

2 The SLD and Hadronic Event Selection

This analysis of data from the SLD mdti-purpose detector [4] used charged tracks mea-

sured in the Central Drift Chamber (CDC) [5] and sficon Vertex Detector (VXD) [6].

The CDC consists of 80 layers of tid or stereo sense wires in a uniform axial mag-

netic field of 0.6 T. The VXD is composed of CCDS contacting a total of 120 fion

22x 22 pm pix& arranged in four concentric layers of rdus between 2.9 and 4.2 cm.

kduding the mcertainty on the primary interaction point (IP), the CDC and VXD

give a combined hpact parameter resolution of ll@76/(pl m) pm, where pl is

the track momentm transverse to the beam tis in GeV/c.

IdentMcation of charged tracks is accomplished with the Cherenkov fig kaging

Detector (C~D) [7]. Through the combined use of fiquid C6Flq and gaseous CSF12

radiators, it is designed to perform efficient charged r/K/p separation over most of

the momentum range up to 46 GeV. Charged particles above Cherenkov threshold

passtig through the radiators etit photons, which are imaged through quartz windows

into time projection chmbers (TPCs) contting a photosensitive gas. The resdting

photoelectrons drift to tie chambers where the conversion point of each is measured

in three&ensions using drift time, wire address and charge &vision. These positions

are used to reconstruct a Cherenkov an~e with respect to each ~rapolated charged

track.

The barrel CMD was fdy operational for most of the 1993-5 runs and was used in

this analysis. The barrel fiquid (gas) radiators cover the polar angle ruge ] cos 61<0.75

(0.67). The Lquid (gas) ind= of refraction was measured to be 1.282 (1.00165), cor-

responding to T/K/p thresholds of 0.17/0.62/1.17 (2.4/8.6/16.3) GeV/c. The average

detected photon yield was 12.5 (9) per ffi ring for tracks with high velocity. The

average Cherenkov angle resolution was 16 (5.5) mrad including the effects of residud

misfignments and track =trapolation resolution. The Iocd or intrinsic resolution was

13 (4) mrad, consistent with the design value. The identification performance of the

barrel CWD is described in the nat section.

The trigger and initial selection of hadronic events is described in [8]. The analysis

presented here is based on charged tracks measured in the CDC and VXD. A set of

cuts w= appfied in order to select events we~-contained within the detector acceptance.

Tracks were required to have (i) a closest approach to the beam As within 5 cm, and

witkn 10 cm along the bem &s of the measured interaction point (IP), (ii) a polar

angle O with respect to the beam tis with [cos 81 <0.80, (iii) a *U momentum

transverse to ttis tis of pl >150 MeV/c, and (iv) a mfimum momentm of p <50

GeV/c. Events were required to contain a -urn of seven such tracks, a thrust [9]

fis polar angle with respect to the beam fis #T within [cos 8T[ <0.71, and a *urn

charged visible energy E“is > 18 GeV, where d tracks were assigned the charged pion

.

m~s. A sample comprising 100,720 events passed these cuts. Of these, 76,445 events

were recorded with a ftiy operational C~D with a good drift velocity cfibration.

Samples enriched in fight ad b primary flavors were selected based on impact

parameters of charged tracks me~ured in the VXD. We define n,:~ as the number of

tracks in an event with normtized transverse hpact parameter with respect to the

IP >3. Events with n,ig = O were ~signed to the fight flavor sample and those with

n,ig ~ 3 were assigned to the b sample. The fight and b samples comprised 60,654 and

14,660 events, respectively, and purities of 86% and 90% were estimated born Monte

Carlo simdations. A more detded discussion of flavor tagging can be found in [10].

CoWsions at SLC are produced by hig~y polarized dectron beams. For the 1993

and 1994/5 -s the average beam polarizations were 6370 and 7770, respectively, and

the beam heficity was selected randody between cofisions. The beam polarization

induces a large asymmetry in the polar an~e distributions of quark jets, which prefer

to fo~ow the dectron (positron) beam direction for left- (right-) handed beam. Each

event was divided into two hemispheres by the plane perpendicdar to the thrust As

~ and tracks with Z. ~ > 0 were assumed to have come from a jet with polar angle

6~ = Cos-l (tz/]tl), where t. is the component of the thrust tis along the electron beam -

&rection. The remaiting tracks were assigned Oh = Cos-l (–iz/ ItI). Hemispheres with

cos d~ > 0.2 produced with left-handed beam and those with cos 6h < —0.2 produced

with right-handed beam were tagged as quark jets. Hemispheres opposite quark-tagged

jets were tagged M antiquark jets. A loose fight event tag, requiring n~ig <1, was dso

appfied. The Standard Modd at tree levd predicts the purities of the quark- and

antiquark-tagged samples to be 7070.

3 Charged Hadron fractions

The charged m, K and p analysis was performed separatdy for the fiquid and gas

ra~ators. b order to ensure that the C~D performance was we~-modded by the

.

simdation, tracks were required to traverse m active region of the radiator in question

and to have their expected ring ftiy contained within a five region of the TPCs. The

Lquid analysis was restricted to the 1993 data sample (22,840 events) and tracks were

reqtired to have u associated tium-iotiing hit in a C~D TPC. For the gas

analysis either the rninimurn-iotiing tit or the presence of at least four hits consistent

tith a fiquid ring was required. For momenta bdow 2 GeV/c, ordy negatively charged

tracks were used since tracks arising from interactions in the detector material are

predominantly positive. b each momentum bin we measured the fractions of the

sdected tracks of the types x, K and p. Electrons and muons were not &stin@shed

from pions in this analysis; this sm~ background was estimated from the Monte Carlo

Simdation (MC) and a correction was apptied. The fractions were then mdtipfied by

the total charged hadron spectrum to obtain production cross sections.

Tracks were identified using a Mkefihood technique. For each of the charged particle

hypotheses a EkeMood w= cdcdated based upon the number of detected photo-

dectrons and their measured an~es, the expected number of photons, the expected .

Cherenkov mgle and a loc~y-measured background that included the effects of over-

lapping rings. Particle separation was based upon differences between logarithms of

these three hkefihoods, Lx, LK and LP. For the Equid (gas) analysis, we define a par-

ticle to be identified as type i if Li exceeds both of the other log-hkehhoods by at least

5 (3), corresponding to 3.2(2.4)u separation.

The efficiencies for identifying selected particles of type i as type j, where i, j =

T, K, p, are shown in fig. 1. The correct identification rates peak near 90% ad the pion

coverage is continuous from 0.5 GeV/c up to approximately 25 GeV/c. MisidentMca-

tion rates in the fiquid (gas) are t~icdy less than 3 (5)% with peak dues of up to 5

(9)%. These efficiencies were detertied through detded detector simdation and were

then cdbrated using data. Figure 2 shows the leftmost column of the previous figure

measured using a high-purity sample of pions from K: decays in the data and com-

pared with the same analysis of the MC sample. The MC reproduces the data within

.

statistical errors. Simdated efficiencies were parametrized as a function of momentum

in order to smooth the effect of &ted MC statistics. The form of the parametrization

of the simdated m ~ T efficiency provides a good fit to the efficiencies extracted using

K: decays, and fitted parameter values for MC and data K: are consistent. For the

fiqtid analysis the parametrized MC was therefore used to define the central values

of the efficiencies. For correct identification the statistical errors on parameter values

from the fit to the K: data were used to define the emors on the effitienties, wtich

are shown in fig. 1 and are corrdated point to point. For misidentification a common

rdative error of 0.16 was assumed, corresponding to one-hti of a typical statistical

error on the K: data points. For misidentification in the gas the MC was &o used for

the central values and a common relative error of 0.25 was assigned. The Htited size

of the Kg data sample does not provide a strong constraint on efficiencies in the gas

analysis, so the total rates of identification u my hadron type in the data ~d MC

were” compared. This resdted in a correction of -1.3% to the T ~ r efficiencies in the

threshold region, 3 < p < 10.5 GeV/c, and -370 to d identification efficiencies above

10.5 GeV/c. The larger of the correction itse~ or the statistical error on the total rate ~

in the data was tden as the error on each point and these errors are stron~y positively

correlated.

For each momentum bin the number of observed particles of a given type can be

related to the true production fraction by an efidency matrix, composed of the entries

in fig. 1 for that bin. This matrix was inverted and used to unfold our observed

identified particle rates. This analysis procedure does not reqtire that the sum of the

charged particle fractions be tity; ~stead the s~ W= used ~ a COnSiStenCy che~

and was found to be in good agreement with unity for d momenta.

The measured charged p~tide fractions for hadronic 2° decays are shown in fig. 3.

k some momentum regions we cannot distkguish two of the three species, so the

procedure was reduced to a 2x 2 analysis and we present ody the fraction of the iden-

tified speeies, i.e. protons in the hquid (gas) analysis above 3 (27) GeV/c and pions

in the gas analysis below 10.5 GeV/c. The errors on the fiquid points are dominated

by systematic which are strongly positively correlated point to ‘point and increase in

magnitude with momentum. The errors on the gas points have rougtiy equal statistical

and systematic contributions, with stiar systematic correlation. Pions are seen to

dominate the particle production at low momentum, to dedne steatiy untfl about 10

GeV/c, and to level off at about tw~thirds. The bn fraction rises steamy to about

one-third at high momentum. The proton fraction rises at low momentum, leveb off

ne= one-tenth at about 10 GeV/c, then de&es above 25 GeV/c. were the momen-

tum coverage overlaps, these measued fractions were found to be in agreement with

previous measurements at the 2° [3, 11, 12]. Measurements b=ed on ring imaging and

those based on ionization energy loss rates [11, 12] cover complementary momentum

ranges and can be combined to provide continuous coverage from 200 MeV/c to 35

GeV/c.

4 Neutral V“ Production

To measure the production of A“/~O and Ko, d pairs of oppositely-charged tracks

were considered as ‘V”” candidates if both tracks had (i) at le~t 40 fits in the CDC,

(ii) Icos 61<0.80 and (iii) pl >150 MeV/c. A verta was fitted to each pair and

the probabtity of the resdting X2 was reqtired to be greater than 2%. The vert=

was required to be displaced from the IP by at least 5 standard deviations, which

accepted V“ candidates with fight lengths as low as 0.2 mm. The angle a=v between

the V“ momentum and the vector from the IP to the vert= in the transverse plane was

required to satisfy la.V \< 5 + 50/pl + 12.5/p~ mrad, where pl is the momentum of

the V“ candidate transverse to the beam tis. Candidates were rejected if their verta

was located outside of the VXD but included a track with more than one VXD hit.

Photon conversions were suppressed by reqfig the e+e- kvarimt mass of the

charged track pair to be greater than 70 MeV/&. WnematicWy-overlapped K: were

rejected from the A“ sample by rejecting W pairs whose ZT invariant m~s was within

3U of the K: mass, wfich removed approximately 30% of the A“ sample. A“ were

removed from the K: sample by requiring [ cos 6“ I < 0.8, where 4“ is the angle between

the positively charged track and the V“ fight direction in the m+~– rest frame, resdting

in a 2070 loss of the K: signal.

The remaining V“ candidates were &tided into bins in both scaled momentum

ZP = 2p/W and ~ = b(W/2p). b each bin the numbers of obsened K: and A“ were

derived from the m~ and ~ invariant mass distributions, respectively, where the faster

track was assigned the proton mass. These numbers were divided by reconstruction

efficiencies estimated from MC to yield production spectra. The reconstruction effi-

ciencies are shown as a function of ~ in fig. 4. As a check the K: and A“ hfetimes were

measured to be ~K: = 2.59 + 0.07 and ~AO = 7.25 + 0.38( stat,) cm in agreement with

world average values [13].

5 Results

Figure 5 shows the production cross sections as a function of scaled momentum ZP =

2p/W for the five me~ured species. For the charged species, cross-sections were ob-

tained by mdtiplying the measured fractions by the total hadrotic cross-section gen-

erated by the JETSET 7.4 sirntiation progr~, which protides a good description of

data at the 2° [14]. The cross sections for charged and neutral kaon production are

consistent. Table 1 shows the tot d production rate per event of each species over the

momentum ruge wtich we measure. The errors are dominated by overd norrn&za-

tion uncertainties.

For comparison with QCD+LPHD predictions the analysis was repeated as a func-

tion of f = h(l/zP). The resdting spectra are shown in fig. 6 and were fitted using

Gaussian approtiations to the prediction [1]. This shape describes the data ade-

quatdy within our point-t~point errors. For the neutr~ and the charged pions the

9

>

data cover the peak we~ and Table 2 fists the peak positions <* obtained horn these fits.

The systematic error is due to variation of the fit range and, in the cme of the charged

pions, the &fference between a fit to the Hquid points ody and a fit in wtich the fiquid

points were deweighted by a factor of 5. We note that fits to the charged kn and

proton spectra give resdts sidar to the neutral kaons and larnbd~, respectivdy.

The pions peak at &gher f (lower momentum) than the other particles, as predicted

by QCD+ LPHD; however, we do not see a substantial peak stit between the kaons

and the baryons. These resdts are in agreement with pretious measurements [3].

Momentum Production Rates per

Particle Range (GeV/c) Hadronic Event

T* 0.7-27 11.12&0.35K+ 0.753 o.74&o.09

K& 10.5-27 o.19ko.02

PIP 1.25-5.5 0.48&0.05

P/F 10.5-36 o.07&o.olKo 0.5-13.7 1.75&o.07

AO/fio 0.5-13.7 0.34&0.02

Table 1: Prefirninary production rates of identified particles in hadrotic 2° decays.

The errors are dominated by overd systematic errors.

Particle f-Peak Position

Table 2: Prtiary spectrum peak positions ({”) for charged pions and neutral kaons

and lambdas.

The analysis was repeated on the bgh-purity fight- and &quark samples described

in section 2. The measured cross sections for these two samples ue shown in fig. 7.

10

There is higher production of both charged and neutrrd kaons and charged pions in the

&tagged sample than in the tight-tagged sample, and lower production of baryons. The

spectra of d species are found to fd more rapidy at low f in the &tagged sample, and

those of the mesons bo fd more rapidy at high f. For the charged pions there is a

difference in fitted peak position of 0.15+0.05 between the fight and &tagged samples.

We do not observe significant differences in peak position for the other species. The

charged hadron fractions for these two samples (not shown) are quite stiar, with the

b sample showing a few percent lower pion fraction in the range 3< p <10 GeV/c, a

tigher pion fraction above 15 GeV/c and a lower proton fraction above 15 GeV/c.

The charged fractions analysis was repeated separatdy on the positively- and

negativdy-charged tracks in the quark-tagged sample described in section 2. The

V“ analysis was repeated separately on canddates with the positively- and negatively-

charged track assigned the proton mass. Tracks and V“s in the antiquark-tagged

sample were included but with their charges reversed. Figure 8 shows the differences

between the baryon and antibaryon production spectra normdzed by their averages,

dx = 2(nx – n~)/(nx + ny), x = p, A“, as a function of scaled momentum. At

low momentum they are consistent with zero, corresponding to equal production of

baryons and antibaryons. The differences me predominantly positive above about 12

GeV/c, corresponhg to an wcess of baryon production, and suggest an upward trend

with momentum. MC studies and the above me~urements in the &sample indicate

that contributions to the baryon and antibaryon samples from heavy hadron decays

are much sm~er than the observed Merences at high momentum. These differences

therefore provide direct evidence that faster patides are more fikely to contain the

initial quark.

6 Summmy and Conclusions

Using the SLD CWD we have made preliminary measurements of charged pion, kaon

and proton production over a large momentum range in hadrotic 2° decays, comple-

menting pretious measurements based on ionization energy loss. The production of Ko

and A“/~o was *O studied. Spectrum shapes were found to be adequately described

by the Gaussian approtiation to the QCD+LPHD prediction. Our resdts for the

~obd sample are in agreement with previous measurements. By isolating high-ptity

fight- and &quark s=ples it was shown that spectrum shapes are tiected by heavy

I

quark fragmentation and decay, but that the effect on the (-peak positions is smd. We

observed a difference in spectra at high momentum between baryons and antibaryons in

a high-purity sample of quark jets, providing direct evidence that particles containing

a primary quark have a harder fiagrnentation spectrum than those that do not.

Acknowledgements

We thank the personnel of the SLAC accderator department and the tecticd staffs

of our co~aborating instutions for their outstanding efforts on our behfi.

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12

List of Authors

● *K. Abe,(2g) I. Abt,(14) C.J. Ahn,(26) T. Akagi,(27) N.J. AUen)(4) W.W. Ash,(27)tD. Aston,(27) K.G. Baird,(24) C. Bdtay,(33) H.R. Band,(32) M,B, Barakat,(n)

G. Baranko,(l”) O. Baron, T. Barrow, A.O. Bazarko,(ll) R. Ben-David,(33)A.C. Benvenuti,(2) T. Bienz,(27) G.M. Bflei,(22) D. Bisdo,(2:) G. Blaylock,(7)

J.R. Bog=t,(27) T. Boston, G.R. Bower,(27) J.E. Brau,(20) M. Breidenbach,(27)W.M. Bugg,(28) D. Burke,(27) T.H. Burnett, P.N. Burrows, W. Busza,(16)

A. Cdcaterra,(13) D.O. Cddwd,(6) D. Cdoway,(27) B. Camanzi,(12) M. CarpineU,(23)R. Cassefl,(27) R. Castddi,(23)(”) A. Castro, M. Cavti-Sforza,(7) E. Church,

H.O. Cohn,(28) J.A. Co~er,(3) V. Cook,(31) R, Cotton,(4) R.F. Cowan,(16)D.G. Cope,(7) A. D’0hveira,(8) C.J.S. Damere~,(25) M. Daoudi,(27) R. De Sangro,(13)

P. De Simon, R. De~’0rso,(23) M. Dims,(g) P.Y.C. DU,(28) R. Dubois,(27)B.I. Eisenstein,(14) R. Efia,(27) D. Fdciai,(22) M.J. Fero,(16) R. Frey,(20) K. Furuno,(20)

T. GWan,(25) G. Gadding, S. Gonzdez,(16) G.D. Hdewe~,(27) E.L. Hart,(2s)Y. Hasegawa,(H) S. Hedges,(4) S.S. Hertzbach,(17) M.D. Hfidreth,(27) J. Huber,(20)M.E. Htier,(27) E.W. Hughes, H. Hwang,(20) Y. Iwasaki,(2g) D.J. Jackson,P. Jacques,( 24) J. Jaros,(27) A.S. Johnson,(3) J.R. Johnson, R.A. Johnson,(8)

T. Junk,(27) R. Kajikawa,(lg) M. Kdek,(24) H. J. Kang,(26) I. Karfiner,(14)H. Kawahara,(27) H.W. Kendd,(16) Y. Kirn,(26) M.E. King,(27) R, King,(27)

R.R. Kofler,(17) N.M. Krishna, R.S. Krueger, J.F, Labs,(27) M. Langston,(20)A. Lath,(16) J.A. Lauder, D.W,G. Leith,(27) M.X. Liu,(m) X, Liu,(7) M. Loreti,(21)A. LU,(6) H.L. Lynch,(27) J. Ma,(31) G. MancineU,(22) S. M~y,(m) G. Mantovani,(22)

T.W. Marhewicz,(27) T. Maruyama,(27) R. M~setti,(22) H. Masuda,(27)T.S. Mattson, E. Mazzucato,(12~ A.K. McKemey,(4) B.T. Meadows,(8)

R. Messier, P.M. Mockett,(31) K.C. Moffeit,(27) B. Mours,(27) G. MWer,(27)D. Mtier,(27) T. Nagarnine,(2T) U. Nauenberg,(l”) H. Ned,(27) M. Nussbaum,(8)

Y. Ohtishi,(lg) L.S. Osborne, R.S. Panvifi,(30) H. Pink,(m) T.J. Pavel,(27)I. Peruzzi,(13)(b) M. Piccolo, L. Piemontese,(12) E. Pieroni, K.T. Pitts,(20)

R.J. Plano,(24) R. Prepost,(32) C.Y. Prescott, G.D. Punkar,(27) J. Qtigley,(16)B.N. Ratdff,(27) T.W. Reeves,(w) J. Reidy,(lg) P.E. Rending, L.S. Rochester,

J.E. Rothberg,(31) P.C. Rowson,(ll) J.J. Russet, O.H. S~ton,(27)S.F. Schtiner,(27) T. Schti,(7) R.H. Schinder,(27) U. SchneeMoth,(16)

B.A. Schumm,(15) A. Seiden,(7) S. Sen,(m) V.V. Serbo,(32) M.H. sh~titz,(ll)J.T. Shank,(3) G. Shapiro, S.L. Shapiro, D.J. Sherden,(27) K.D. Shmakov,(n)

C. SkOpOdOS,(27) N.B. Sinev,(20) S.R. Smith,(27) J.A. snyder,(~) P. Stmer,(Z4)H. Steiner, R. St~er,(l) M.G. Strauss, D. SU,(27) F. Suekane,(2g)

A. Sugiyama,( 19) s. SUW,(19) M. Swutz,(2T) A. Sz~o,(31) T. T~M~,(27)

F.E. Taylor, E. Tomence,(16) J.D. Turk,(a) T. Usher,(27) J. Va’vra,(27)ti,(23) E. VeUa,(27) J.P. Venuti,(m) R. Vernier, P.G. Verti,(23)c. v

S.R. Wagner, A.P. Waite,(27) S.J. Watts,(4) A.W. Weidemann,(28) E.R. Weiss,(31)J.S. Whitaker,(3) S.L. Wte,(2a) F.J. Wickets, D.A. Wfiams,(7)D.C. WWams,(16) S.H. Warns, S. Wtiocq,(m) R.J. Wfion,(g)

W.J. Wisniewski,(s) M. Woods,(27) G.B. Word,(24) J. WySS,(21) R.K. Yamamoto,(16)J.M. Yamartino,(16) X. Yang,(20) S.J. Yeh,(6) C.C. Young,(27) H. Yuta,(2g)

13

I.

G. Zapdac,(32) R.W. Zd=ko,(27) C. Zeitfin,(20) Z. Zhmg,(16) and J. Zhou,(zo)

(l)Adelpht University, Garden City, New York l1530(2)INFN Setione da Bologna, I-J0126 Bologna, Italy(3)Boston University, Bo9ton, Massachusetts 02215

(4)Brunei University, Uzbridge, Middlesez UB8 9PH, United Kingdom(s) Cdifomia Institute of Technology, Paadena, California 91125

(6) University of Cdifomia at Santa Barbam, Santa Barbam, C&ifomia 93106(7)univeT~atYOf Cdifomia at Santa Cm, Santa C-, C~ifo~ia g5064

(8) University of Cincinnati, Cincinnati, Ohio 45221(9)Colorado State University, Fort Collins, Colorado 80529

(lo) University of Colorado, Boulder, Colorado 80909(Ii) Columbia University, New York, New York 10027

(12)INFN Sem.one di Ferraro and Univer9it h di Ferraro, I-~~ 100 Ferraro, Italy(13)INFN Lab. Nu.onali di &ucati, I-000~~ ticati, Italy

(1*)University of fllinois, Urbana, fllinois 61801(lS)Lawrence Berkeley Labomtory, University of California, Berkeley, California

9A720(16)Mmsachwetts Institute of Techn~logy, Cambridge, Mas9achmetts 02139

(17)University of Massachusetts, Amherst, Massachusetts 01009~~a~University of Mis9is9ippi, University, Mis9is9ippi 98677

(lg)Nagoya University, Chikus~ku, Nagoya ~64Japan(2°) University of Oregon, Eugene, Oregon 97403

(21)INFN Sezzone di Padova and University di Padova, I-351OO Padova, Italy(22)INFN Sezaone di Pen9ia and Univer9ith di Perugia, I-06100 Pemgla, Italy

(23)INFN Sezaone da p~a and University di Pisa, I-561OO Pisa, Italy

(24)Rutgers University, Piscataway, New Jersey 08855(25)Rutherfoti Appleton Laboratory, Chilton, Didcot, Ozon OX1l OQX United

Kingdom(2G)Sogang University, Seoul, Korea

(27)Stanford Linear Accelerator Center, Stanford University, Stanford, California94309

~28~University of Tennes9ee, Knomlle, Tenne9see 37996~2g~Tohoku University, Sendai 980 Japan

~mlVanderbilt University, Nashdle, Tenne99ee 3723513~~University of Washington, Seattle, Wahington 98195(321University of Wigconsin, Madison, Wisconsin 53706

~m~Yale University, New Haven, Connecticut 06511

tDeceased(“)Ako at the Univer9ith di Genova~b~Ako at the University di Pemgia

14

Figure captions

1. Identification efficiencies for charged m*, K*, and p/P in the SLD barrel C~D,with systematic errors. The open symbols are for the analysis using fiquid radi-ator information; the sofid symboh are for the g~eous radiator.

2. Identification efficiencies for charged 7* measured with pions from K: decays(sofid symboh). The open tides are for the same analysis of a Monte Carlosample.

3. Prtiary charged hadron fractions measured by SLD. Circles are T*, squaresare K*, and triangles are p/~. Open symbob are for the Lqtid radiator; sobdsymbob are for the gas.

4. The efficiency for reconstructing and selecting a) Ko and b) A“ decays in sdectedhadrotic 2° decays recorded by SLD. The efficiencies include the branching ratiosand effects of detector acceptance.

5. Preliminary production spectra per event vs. scaled moment& ZP = 2p/W forZ* (dots), K* (squares), Ko (open squares), p/~ (trian~es), and A“/~o (open

tnan~es) in inclusive hadronic 2° decays. The p/p and A“/~o spectra have beenscaled by 0.2 and 0.1, respectively. The errors are statistical and systematic inquadrature. The systematic errors on the charged species are dominant and arecorrelated point to point. An over~ norm& ation uncertainty of 4% on theneutral species is not included.

6. Prehmin=y production spectra per event vs. ~ = – b(zP) for a) m+, b) K*,

2c) Ko, d p/fi, and e) A“/~o in inclusive hadronic 2° decays. The errors aredescribe in the caption for fig. 5. The curves are resdts of Gaussian fits.

7. Preliminary production spectra per event vs. ~ = – b(z,) for a) r+, b) K+, c)Ko, d) p/~, and e) A“/~o in samples enriched in 2° ~ ufi, d~, S3 decays (sohdsymbols) and 2° + b~ decays (open symboh), Ody statistical errors are shown.

8. The difference between p and F (circles) and A“ and lo (squares) productionspectra in quark-tagged jets, norm&ed by their average in each bin. Ordystatistical errors are shown.

15

. Figure 1: SLD CRID Identification Efficiencies(Preliminary)

K + “n”0,12[ I I 0.12

p + “n”I I I I

0.10-

0.06-

]Iii0.06–

&v

-1+{] ~11~~

1

0.04

Py \10.02- & ,

11

I I I ‘k]02 10 20 50

n + “K“ K + “K” p * “K“‘“’2~ “o~ “21 I I I

0.12r in + “p”

I I I

1

[

0.10’

0.08

[O.m– i

4-

]

wI

O.w-Ml

0.02- ~~

I AI bI I I

02 0.5 1 2 5 10 20 50

K + “P”0.12 I I

0.10

0.08 1

O.m-

,*1 i: :‘‘‘‘:jl-

0.04-

0.02-+

4A+0.2 0.5 1 2 5 10 20 50

0.08

0.06

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I0.02–

i

1 1! i-

0.2 0.5 1 2 5 10 20 w

1.0.p + “p”

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0.8 - & 4

4 ‘i-4 “~

0.6 -i

A ?

0.4–4

\

;_

0.2- A

iA

I I I I I I0.2 0.5 1 2 5 10 20 50

p (GeV/c)

Figure 2: Determination of Liquid ID Efficiencies

using K~” + zn

0.06

0.04

0.02

0.08

0.06

0.04

0.02

0123456

I 1 I I I I

n + “K“

01

I I

012345~

I I 1 I I I

z + “p”

I,1 I

p (GeV/c)

●

1.0

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0.0

Figure 3: SLD Preliminary Fractions

I,

} IT

1 I I !

—1

T

T

-— I

_I

—

1 10

p (GeV/c)

w

Figure 4: VO Reconstruction Efficiencies

(Preliminary)

0.14

0.12

0.10

0.08

0.06

0.04

0.02

0.30

0.25

0.20

0.15

0.10

0.05

a)

●●

I

Ko -

●

●

●

●

0“

O.OO12 3 4

< = In (1/xp)

b) A“

●

O.OO1 I I I

2 3 4

5

5~ = In (1/xp)

●

✼✎

.

Figure 5: SLD Preliminary Spectra

103L

102

110’

10°

AI

T—10-’

10-2I

TI I I 1

10-2 10-’ 10°

‘P

I10-3

Figure 6: SLD Prelimina~ Production Spectra

0 1- 2 :

\

~ I , I I

)4 5 6

1.4 i I I I

12L b) P.1

1.0;

, (

0 1 23456

1.4 i,i I

1.2- c) Ko I1

1.0- 4

$~1o 1 23456

~ = In (1/xp)

0.5 I I I I

d)0.4 -

0.3 -

0.2 -

01 2 345

0.25, i

~ e)

I I

A“’~(0.20 f

o.15i

O.lot

till>0.05 ~1

“), J

1

01 23456

~ = In (1/xP)

.

uds- and b-Tagged SpectraFigure 7: SLD Prelimina~

0.5

0.4

0.3

0.2

0.1

I

a)

I I

7

6

5

4

3

2

1

d)

I

Lo ‘1 2 345 6 1 234 .

1.4[ I I I I 0.25

0.20

0.15

0.10

0.05

b) e)1.2L

1.0 “,

-0.8 r0.61

r

0.4 rB v

0.2 ~

‘n❑

01 2345I

11I I i I

1 23456

~ = In (1/xP)1.4

1.2

1.0

0.8

0.6

0.4

0.2

1

c) Ko

< = In (1/xP)

2.0

1.5

1.0

0.5

0.0

-0.5

Figure 8: Comparison of bayon and antibayonproduction in quark jets

I I I

SLD Preliminary

.

-1.0 —o

1

. ...- ~.. .

c1 j

I

10 20 30

● X=pO X=A

---- . . . . . . . . . . . . .

I

40

p (GeV/c)