June 29, 1999 ZEUS Report : 47. DESY PRC 1 ZEUS Status Report: June 1999 A Word on the Spring 1999 e - p Luminosity Run Performance u Physics Highlights

June 29, 1999 ZEUS Report : 47. DESY PRC 1

ZEUS Status Report: June 1999

A Word on the Spring 1999 e-p Luminosity Run Performance

Physics Highlights From Recent AnalysesA(nother) Guided Tour Along Q2, including

•Photoproduction of jets and of charm

•Deep Inelastic Scattering (DIS) production of charm and dijets

•Inclusive Scattering at the Highest Q2

Progress on Approved Tracking UpgradesStraw Tube Tracker Microvertex Detector

Bring on the Positrons !

Danny Krakauer

Argonne National Laboratory


Summary of the 1999 e - p Run

Rapid ramp up to nominal efficiency (as per 1996/1997, w/

short Winter break) Achieved 70 % efficiency relative to useful lumi. Improved over 98, approaching 97 record.

Dealt with Coasting Protons problem at the trigger level Two-Person shift crews

Ldt = 11.4 pb-1


About to embark on tour of (quite) recent ZEUS results

A very broad and deep program, that’s also a lot of “fun”.

Some statistics to illustrate the activity: From January - August, ZEUS physicists will give

105 invited or contributed conference presentations.Since last PRC meeting, 5 EPJC articles have been

submitted/accepted, 4 more have passed collaboration “readings”, and xx more are advanced to pre-reading stage.

Last week, an exciting collaboration week with over 30 physics presentations and extended discussions. Many new results approved for public talks - Many new results approved for public talks - including three or four in this summary.including three or four in this summary.

And now let’s embark on our


Kinematic Range of (x,Q2) Explored at HERA


Examples of LO processes

e -e -

g

p

proton remnant

q

q

g

proton remnant

q

gq

p

e -e -

photon remnant

LO direct x = 1

LO resolved x < 1

ysWEEyQQE

E

eEx

E

eEx

epT

p

jets

jetT

pjets

jetT

jetjet

/

2 ,

2222

OBSOBS

Additional Variables in Photoproduction


Subjets in photoproduced jets

Quark and gluon jets are expected to be different due to differentqg and gg couplings.

Investigate structure of jets by looking for subjets.


Subjet Multiplicity

Subjet analysis senses differences in multiplicity and width of jets:

Njet quarks Njet gluons


Subjet Multiplicity

Njet Ycut as Forward Jets more glue-like


Trijet Photoproduction

(leading jet)

(2nd jet)

(3rd jet)

3: scattering angle of th Leading Jet in the 3J CM. Angular distributions

reflective of reaction dynamics (quark/gluon)

In three jet events, the 3rd jet allows identification of fwd/back direction of leading jet in the 3J CM


Low-W photoproduction of Charm

Differential cross sections

Data lie above NLO calculations

Events are tagged by hits in the “44m” tagger -

80 GeV < W < 120 GeV


From D* in DIS ccF2

FINAL


From D* in DIS

2Q

F2C

/ F2

x

Contribution of charm in DIS grows with

Fraction of charm increaseswith decreasing x.

ccF2


Measurement of s in dijet DIS

...)Q(c)Q(c)Q( ; )Q(

)Q()Q(R 22

s22

s12

122tot

2122

12

Select dijet events with :

frame)(Breit GeV 17EE ; GeV 5E ,E

frame) (Lab. 21- ; GeV 470Q2jet

T1jet

T2jet

T1jet

T

jet22

Region of small experimentaland theoreticaluncertainties

Compare measured dijet ratio to NLO calculations (DISENT)

(theory) (exp.) (stat.)003.0120.0)( 0.0030.002-

0.005 0.006 -

Zs M

Measure s from dijet cross section 2+1 and ratio:


Searches For New Physics in e-p

Data in Good Agreement w/ SM

Search for Isolated High Pt Muons

or Electrons in e-p

Study of High (x,Q2)

e-p NC DIS

First 8.6 pb-1 of 1998/99

One Candidate in First 5.1 pb-1 of e-p data

before lepton cut

Exp Bkg = 0.50

after Lepton ID0.24 0.14 e0.24 0.03

Firs

t 5.

1 pb

- 1 o

f 1

998

dat

a


High Q2 Neutral Current DIS


High Q2 Neutral Current DIS

Direct Sensitivity to Z0-boson exchange


High Q2 Charged Current DIS

pe

pe

pe

Comparison of e+p to e- p at high Q2


High Q2 Charged Current DIS

)sd()y1(cudxdQ

)pe(d 22

CC2

cu)sd()y1(dxdQ

)pe(d 22

CC2


Charged Current & high-x quarks

Differences due to quark density and helicity Potentially, direct extraction of d:u quark ratio and estimates of high

Q2 sea quark distributions…. And… And… And… Polarization (w/Lumi) will help ….


Looking Ahead to High Luminosity


Subcomponents newly operational in 1999

Barrel Presampler: Energy corrections for hadrons and electrons over full

detector, with minimal use of MC BPRE useful for 0/ separation

Forward Neutron Tracker Scintillator fingers at 10 inside FNC for precise

reconstruction of impact point. Improved Pt resolution for t-dependent studies

BPREsampler Forward Neutron Tracker

e-


StrawTube Tracker (STT)

Beam-tests at DESY of prototype sector and prototype electronics: Multiplexing Scheme for digital readout designed, final

prototype being produced STT Short sector production to begin next month, Long

sector design complete. Beamtest of STT, end-to-end, in September


Microvertex Detector (MVD)

Barrel MVD Si acceptance tests, Forward MVD Si prototyping Cabling and Interconnects - orders soon Bonding and module production underway at DESY (Halle 1) now. Progress on readout and trigger… MVD will participate at the

Second Level “Global Tracking” (CDT,STT,MVD) trigger.

Much progress on all aspects of project goals.

FMVD first prototype, ready for test beam

Bonding machine at DESY


End of Talk / Start of Next Run

ZEUS is enjoying a rich variety of Physics Investigations A quick tour through Q2 with peaks at precision measurements of s, growing program in heavy flavors, searches for Exotics and measurements of weak-effects in DIS, STILL leaves out the vast majority of an active and growing Physics environment.

New results from ZEUS are coming all the time.

ZEUS is ready to maximize collection of ep data before the Upgrade. Last chance for some detectors and some physics.

Progress on Lumi-Upgrade : Both new Trackers are meeting goals to be ready. The existing trigger and R/O components are ready NOW.

Documents

June 29, 1999 ZEUS Report : 47. DESY PRC 1 ZEUS Status Report: June 1999 A Word on the Spring 1999 e - p Luminosity Run Performance u Physics Highlights