Post on 15-Jan-2016
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
June 29, 1999 ZEUS Report : 47. DESY PRC 2
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
June 29, 1999 ZEUS Report : 47. DESY PRC 3
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
June 29, 1999 ZEUS Report : 47. DESY PRC 4
Kinematic Range of (x,Q2) Explored at HERA
June 29, 1999 ZEUS Report : 47. DESY PRC 5
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
June 29, 1999 ZEUS Report : 47. DESY PRC 6
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.
June 29, 1999 ZEUS Report : 47. DESY PRC 7
Subjet Multiplicity
Subjet analysis senses differences in multiplicity and width of jets:
Njet quarks Njet gluons
June 29, 1999 ZEUS Report : 47. DESY PRC 8
Subjet Multiplicity
Njet Ycut as Forward Jets more glue-like
June 29, 1999 ZEUS Report : 47. DESY PRC 9
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
June 29, 1999 ZEUS Report : 47. DESY PRC 10
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
June 29, 1999 ZEUS Report : 47. DESY PRC 11
From D* in DIS ccF2
FINAL
June 29, 1999 ZEUS Report : 47. DESY PRC 12
From D* in DIS
2Q
F2C
/ F2
x
Contribution of charm in DIS grows with
Fraction of charm increaseswith decreasing x.
ccF2
June 29, 1999 ZEUS Report : 47. DESY PRC 13
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:
June 29, 1999 ZEUS Report : 47. DESY PRC 14
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
June 29, 1999 ZEUS Report : 47. DESY PRC 15
High Q2 Neutral Current DIS
June 29, 1999 ZEUS Report : 47. DESY PRC 16
High Q2 Neutral Current DIS
Direct Sensitivity to Z0-boson exchange
June 29, 1999 ZEUS Report : 47. DESY PRC 17
High Q2 Charged Current DIS
pe
pe
pe
Comparison of e+p to e- p at high Q2
June 29, 1999 ZEUS Report : 47. DESY PRC 18
High Q2 Charged Current DIS
)sd()y1(cudxdQ
)pe(d 22
CC2
cu)sd()y1(dxdQ
)pe(d 22
CC2
June 29, 1999 ZEUS Report : 47. DESY PRC 19
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 ….
June 29, 1999 ZEUS Report : 47. DESY PRC 20
Looking Ahead to High Luminosity
June 29, 1999 ZEUS Report : 47. DESY PRC 21
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-
June 29, 1999 ZEUS Report : 47. DESY PRC 22
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
June 29, 1999 ZEUS Report : 47. DESY PRC 23
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
June 29, 1999 ZEUS Report : 47. DESY PRC 24
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.