HERAII results on inclusive crosssections

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HERA-II results on inclusive cross-sections
A .M. Cooper-Sarkar Oxford On behalf of ZEUS and
H1 at the low-x workshop, Lisbon 2006

• Neutral Current (NC) and Charged Current (CC)
  single and double differential cross sections
  from 03-05 running with polarised e and e-
  beams
• Polarisation dependence of cross-sections
• Limits on MWR
• Extraction of xF3
• New PDF fit- reduced high-x uncertainties
• Fits for electroweak parameters
• 
  MW, GF,, g
• 
  au,vu,ad,vd,
• 
  T3u,T3d, sin2?W, T3uR,T3dR

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New data with polarised lepton beams for both
Neutral Current (NC) and Charged Current (CC)
processes
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New data with polarised beams
-- ep cross sections have been published.
ZEUS hep-ex 0602026 H1 Phys Lett B634 (2006)
173 -- ep analyses (preliminary)
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The data has been used for new fits to improve
our knowledge of parton distributions (PDFs) and
electroweak parameters First Charged Current
results
(At leading order LO)
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ZEUS polarisation dependence of e and e-
ep CC cross section (hep-ex 0602026)
ep CC cross section (ZEUS preliminary)
Both for ep and ep, measured cross sections
from different polarisations have the same
shape.Only their scales are different.Consistent
with SM prediction gt
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H1 dependence of cross-section on charge of
lepton
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(Q2 gt 200 GeV2)
H1 (Q2 gt 400 GeV2)
ltPegt0.270.01
ltPegt0.270.01
?e-p 70.4 1.2(stat.) 3.1(sys) pb
ltPegt0.370.02
ltPegt0.330.02
?e-p 34.5 1.4(stat.) 1.5(sys) pb
Consistent with SM the limit on RHCC
cross-section corresponds to 95 CL on mass of
WR boson, MWRgt180 GeV ZEUS MWRgt186 GeV H1
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ZEUS preliminary
Cross sections were meausured as a function of
Pe. Linear relation between cross section and
polarisation is clearly shown.
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Now Neutral Current Results
-y2FLo/p
At leading order (LO)
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Positron single differential cross-sections
H1
d?/dQ2 ep RH,LH and RH/LH
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Electron single differential cross-sections
H1
d?/dQ2 e- p RH,LH and RH/LH
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H1 ?(Unpolarised)
H1 xF3
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ZEUS also has preliminary results on polarised
double differential cross-sections for both CC
and NC processes- these are shown with a new PDF
fit ZEUS-pol.
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ZEUS also has preliminary results on polarised
double differential cross-section for both CC and
NC processes- these are shown with a new PDF fit
ZEUS-pol
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So what is this new PDF fit? ZEUS-pol It is done
with exactly the same formalism as the published
ZEUS-JETS fit (Eur.Phys.J.C42(2005)1) -but adding
in the double differential cross-sections for NC
and CC data from 121 pb-1 of the new HERA-II e-p
05 polarised data
Precision of xuv now approaches that of global
fits using fixed target data
Expected since NC and CC e- are dominantly
sensitive to u quark
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ZEUS have also made an analysis varying the
electroweak parameters simultaneously with the
PDF parameters within the same fit formalism
-y2WL(x,Q2)
This was from the shape of CC d?/dQ2
This was from a similar PDFEW analysis on HERA-I
H1 data
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Let the neutral current axial vector and vector
couplings au,vu,ad,vd be free
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These results are best displayed as contour
plots Compare to the red contours determined in
the same way BUT without polarised
data Improvement in the vector couplings as
expected from polarised F2 data
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Compare the result with those from other
experiments H1 analysis of HERA-I data LEP and
CDF analyses
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In fact for DIS data the sensitivity to the
couplings is through ?/Z interference to the
axial vector couplings (from xF30) and vector
couplings (from F2P) separately not to the
combinations ( a2 v2) which LEP and CDF data
access through the Z - so we plot the axial and
vector contours separately
The improvement in the vector couplings with
polarised data is striking
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We can also make fits within the standard model
formalism
OR we can extend the standard model formalism
with right handed isospin
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Summary

• New data on Neutral Current (NC) and Charged
  Current (CC) single and double differential cross
  sections from 03-05 running with polarised e
  and e- beams
• Polarisation dependence of cross-sections in
  agreement with Standard Model
• Limits on MWR MWRgt180 GeV ZEUS MWRgt186 GeV
  H1
• Extraction of xF3
• New PDF fit- reduced high-x uncertainties-
  particularly for xuv
• Fits for electroweak parameters MW best
  measurement for space-like process
• 
  GF,, - at high scale Q2
  400 GeV2
• vector and axial vector NC couplings
  au,vu,ad,vd,
• 
  T3u,T3d, sin2?W, T3uR,T3dR
• In agreement with Standard Model best
  measurements using light quarks