1. 28/04/2000 DIS 2000 - Liverpool, April 28th 1 QCD with W/Z-events Ursula Bassler, LPNHE-Paris in behalf of the CDF and DØ collaborations Basics on W/Z at the Tevatron W/Z-production:   Drell-Yan cross-section   d  /dP T for W and Z   W/Z+jet production W-decay:   angular dependence of decay lepton   lepton charge asymmetry

2. 2 Basics of W and Z production  W/Z production from qq annihilation  , p T distribution depend on pdf  large production  selection based on leptonic decays  W  l (BR: 11 % per mode) E T (l) > 25 GeV, E T ( ) > 25 GeV  Z  ll (BR: 3% per mode) 2 isolated leptons, E T (l) > 25 GeV  Run 1A: 20 pb -1 Run 1B: 80 pb -1 (Run 0- CDF: 4pb -1 )   60k W-events,  5k Z-events /exp. kinematic variables: l l’

3. 3 Drell-Yan cross-section   access region at x > 0.02 and up to Q 2  15000 GeV 2   high mass Drell-Yan: sensitivity to new physics   good agreement with NLO-calculation

4. 4 Drell-Yan cross-section: low mass   update of low mass Drell- Yan cross-section with reduced statistical errors   ee and  channel in good agreement   consistent with expected behavior:

5. 5 Drell-Yan at high rapidity  special analysis with leptons in the forward region  y=1/2 ln x 2 /x 1  access high x region  good agreement with gluon resummation calculation

6. 6 p T dependence in W/Z-production O(  ): W/Z bosons produced with p T =0   p T attributed to gluon radiation, expected to broaden with Q 2 : M  10 GeV   1 GeV   M  80 GeV   5 GeV   M  91 GeV   6 GeV   measurements of d  /dp T : W  higher statistics, Z  better resolution,W q q q qq q

7. 7 Z-production at high p T   d  /dp T (Z) measured at 1 < p T < 230 GeV   cross-section falls over 5 orders of magnitude   perturbative QCD at O(  2 ) describes data at high p T

8. 8 Z-production at low p T   at low p T soft gluon radiation dominates   resummation of large ln(Q 2 /p T 2 ) terms   p T  0: parameterize non-perturbative contribution 2 formalisms possible:   b-space resummation  impact parameter space   q T -space resummation  transverse momentum space

9. 9 fit of Sudakov Form Factor   best description from Ladinsky-Yuan parameterization: fit to low mass Drell-Yan and d  /dp T from CDF on Run 0 data   non-perturbative Sudakov Form Factor: S NP LY =g 1 b 2 +g 2 b 2 ln(Q 2 /Q 0 2 )+g 1 g 3 b ln(100x i x j )   new fit of g 2 =0.59±0.06 GeV 2, reduced error   g1 and g3 in agreement with LY-value, similar error

10. 10 p T dependence in W-production  d  /dpT(W) measured at 1 < p T < 180 GeV  error dominated by: low p T : hadronic resolution high pt: statistics and backgrounds  good agreement with NNLO QCD + low pt gluon resummation DØ preliminary — — MRSA’ - NNLO+res.

11. 11 W/Z+jet production  hard gluon radiation produces additional jets   (W/Z +  1j)/  (W/Z) depends on  S   (W/Z +  Nj) in good agreement with LO-calculation  soft scale 2 favored

12. 12 angular dependence in W-decay q sqsqsqsq sqsqsqsq sWsWsWsW q sqsqsqsq sqsqsqsq sWsWsWsW O(  ) QCD g in W-rest frame: 2222

13. 13 charge asymmetry in W-decay  constraints d/u ratio  measurement at Q 2  M 2 W and 0.006 < x < 0.34  CDF: combined e+   DØ:  only u d W+W+W+W+ W-W-W-W-

14. 14 Conclusions  W and Z bosons allow QCD studies using leptonic signatures, both in production and decay  Run II will start in march 2001:  increased statistics (2 fb-1 / 2 years)  improved detectors  new and interesting results!