Transcript Exploring the Standard Model with JLab at 12 GeV Paul E. Reimer Argonne National Laboratory 17 January 2003 • Standard Model tests: Beyond sin2(qW). • e2ePV:

Exploring the Standard Model with
JLab at 12 GeV
Paul E. Reimer
Argonne National Laboratory
17 January 2003
• Standard Model tests: Beyond sin2(qW).
• e2ePV: Moller Scattering at 11 GeV
• DIS-Parity: Parity NonConserving Electron Deep Inelastic
Scattering
For Dave Mack, Paul Souder, Michael Ramsey-Musolf, et al.
sin2(qW) measurements below Z-pole
• Standard Model predicts sin2(qW) varies (runs) with Q2
– Non-S.M. physics may move measurements away from running curve.
– Different measurements sensitive to different non-S.M. physics.
– Well measured at Z-pole, but not at other Q2.
• NuTeV nA scattering:
– 3s from Standard Model!!!
– Fe target: PDF’s in iron? Nuclear corrections?
• Atomic Parity Violation (APV):
– Hard to understand theoretically.
– Consistent with S.M. (plot is out of date)
• Qweak (Jlab)
• E158-Moller
•e2ePV
•DIS-Parity
– Qweak PROTON
– ¼ 2005-07
–11 GeV-Moller
Scattering
–Q2 = 0.008 GeV2.
17 January 2003
– QWeak ELECTRON
– Final run 2003
Future measurements
–11 GeV JLab DIS Parity
Violation
–Q2 = 3.5 GeV2
Paul E. Reimer, Argonne National Laboratory
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Beyond sin2(qW): e.g. SUSY and Dark Matter
What is Dark Matter?
•S.M.: QWelectron and QWproton both
measure 1-4sin2(qW).
•SUSY: Loop contributions can
change this by measurable
amounts!
hep-ph/0205183
NASA Hubble NGC3310
RPV
No SUSY
dark matter
JLab QWeak (proton)
and SLAC E158
Moller (QWe)
anticipated limits.
17 January 2003
Paul E. Reimer, Argonne National Laboratory
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e2ePV: Parity Violating
Moller Scattering at 12 GeV
D. Mack, W. van Oers, R. Carlini,
N. Simicevic, G. Smith
17 January 2003
Paul E. Reimer, Argonne National Laboratory
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e2ePV: Moller Scattering at 12 GeV
• Measurement of QWeak of the electron.
• Very small asymmetry:
A|11 GeV ¼ 9¢10-7 (1 – 4 sin2qW) ¼ 4¢10-8.
• Near-vanishing of the tree-level asymmetry makes this
measurement sensitive to
•New physics at tree-level (e.g. Z0),
•New physics via loops (e.g. SUSY loop contributions).
Restriction the available parameter space by a small amount is
useful!
• Is there room for JLab to improve on the SLAC E158
measurement? What type of apparatus would be needed?
17 January 2003
Paul E. Reimer, Argonne National Laboratory
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Moller sin2 qW Error De-Magnification
sin2(qW) ¼ 0.238
1 - 4 sin2(qW) ¼ 0.05
Radiative corrections
• Not all of which are suppressed (De-Magnified) by (1-4sin2(qW)
• Reduce tree-level Moller asymmetry by ¼ 40%
17 January 2003
Paul E. Reimer, Argonne National Laboratory
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Moller 12 GeV vs. 48 GeV
Repeat SLAC-E158
Moller
• Figure of merit:
• A2 ds/dW / Ebeam.
• Factor of 4 better at
SLAC.
• All else equal, the
advantage goes to the
higher beam energy—
but “all else” is not
equal!!
• JLab can have a clear
advantage in luminosity.
17 January 2003
Paul E. Reimer, Argonne National Laboratory
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JLab 12 GeV Moller vs. SLAC E158
JLab’s advantage comes from the higher
integrated luminosity available.
17 January 2003
Paul E. Reimer, Argonne National Laboratory
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Moller sin2(qW) Anticipated Uncertainties
Clearly a competitive measurement of sin2qW is possible at 11 GeV which is
competitive with the best single measurements below and at the Z-pole.
17 January 2003
Paul E. Reimer, Argonne National Laboratory
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Moller Detection
Laboratory scattering angles
are small!!
Detector Requirements:
• Focus Moller electrons of
momentum 4.5 GeV/c § 33%.
• Toroidal magnet with 1/R field is
well suited.
• Field requirement are less and
scattering angle larger than at SLAC
17 January 2003
Detector Concept:
• Drift scattered electrons to a collimator.
• Focus electrons in a resistive toroidal
magnet.
• Drift electrons to detector ring.
Paul E. Reimer, Argonne National Laboratory
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e2ePV Moller Conclusions
• There is a small window for
a Moller exp. at JLab to
improve over SLAC E-158.
• This improvement can have
a significant impact on the
range of allowable SUSY
extensions.
hep-ph/0205183
RPV
No SUSY
dark matter
JLab QWeak (proton)
and JLab e2ePV
Moller (QWe)
anticipated limits.
17 January 2003
Paul E. Reimer, Argonne National Laboratory
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DIS-Parity: Polarized e- deuterium
Deep Inelastic Scattering Parity
NonConservation
Paul Reimer, Peter Bosted, Dave Mack
17 January 2003
Paul E. Reimer, Argonne National Laboratory
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Textbook Physics:
Polarized e- d scattering
•
•
•
•
Repeat SLAC experiment (30 years later) with better statistics
and systematics at 12 GeV Jefferson Lab:
Beam current 100 mA vs. 4 mA at SLAC in ’78
£ 25 stat
60 cm target vs. 30 cm target
£ 2 stat
Pe (=electron polarization) = 80% vs. 37%
£ 4 stat
d Pe ¼ 1% vs. 6%
£ 6 sys
17 January 2003
Paul E. Reimer, Argonne National Laboratory
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DIS-Parity: Polarized e- deuterium DIS
Longitudinally polarized electrons on
unpolarized isoscaler (deuterium) target.
C1q ) NC vector coupling to q
£ NC axial coupling to e
C2q ) NC axial coupling to q
£ NC vector coupling to e
17 January 2003
Note that each of the Cia are
sensitive to different possible S.M.
extensions.
Paul E. Reimer, Argonne National Laboratory
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DIS-Parity: Detector and Expected Rates
• Expt. Assumptions:
–
–
–
–
–
–
60 cm ld2/lH2 target
11 GeV beam @ 90mA
75% polar.
12.5± central angle
12 msr dW
6.8 GeV§10% mom. bite
• Rate expectations:
–
–
–
–
¼ 1MHz DIS
p/e ¼ 1 ) 1 MHz pions
2 MHz Total rate
dA/A = 0.5% ) 2 weeks
(ideal) plus time for H2 and
systematics studies.
Will work in either Hall C (HMS +SHMS) or Hall A (MAD)
hxi = 0.45 hQ2i = 3.5 GeV2
hYi = 0.46 hW2i = 5.23 GeV2
Q2 near NuTeV result—provide
cross check on neutrino result.
17 January 2003
Paul E. Reimer, Argonne National Laboratory
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• Beam Polarization:
Uncertainties in Ad
–This drives the uncertainty!
–QWeak also needs 1.4%
–Hall C Moller claims 0.5%.
• Higher twists may enter at low Q2:
–This could be a problem.
–Check by taking additional data at lower
and higher Q2.
–Possible 6 GeV experiment?
• Ad to § 0.5% stat § 1.1% syst.
(1.24% combined)
Statistical (2 weeks)
0.5%
Beam polarization
1.0%
dQ2
0.5%
Radiative corr.
<1%
dR = d(sL/sT) = §
15%
<0.02%
ds(x) = § 10%
<0.03%
EMC Effect
????
Higher Twist
????
What about Ciq’s?
17 January 2003
Paul E. Reimer, Argonne National Laboratory
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Extracted Signal—It’s all in the binning
PDG: C1u= –0.209§0.041 highly
C1d= 0.358§0.037 correlated
2C2u– C2d = –0.08§0.24
This measurement:
d(2C1u– C1d) = 0.005 (stat.)
d(2C2u– C2d) = 0.014 (stat.)
17 January 2003
Note—Polarization uncertainty
enters as in slope and intercept
Aobs = PAd / P(2C1u–C1d) +
P(2C2u–C2d)Y]
but is correlated
Paul E. Reimer, Argonne National Laboratory
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DIS-Parity determines 2C2u-C2d
Combined result significantly constrains 2C2u–C2d.
PDG 2C2u–C2d = –0.08 § 0.24 Combined d(2C2u–C2d) = § 0.014
£ 17 improvement (S.M 2C2u – C2d = 0.0986)
17 January 2003
Paul E. Reimer, Argonne National Laboratory
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DIS-Parity: Conclusions
• DIS-Parity Violation measurements
can easily accomplished at JLab
with the 12 GeV upgrade (beam and
detectors) in either Hall A or Hall C.
• Large asymmetry/quick experiment.
• Requires very little beyond the
standard equipment which will
already be present in the halls.
• Near NuTeV Q2.
d(2C1u – C1d) = 0.005
d(2C2u – C2d) = 0.014
• Higher twist may be important
17 January 2003
Paul E. Reimer, Argonne National Laboratory
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JLab tests of the Standard Model
• Measurements of sin2(qW) below MZ
provide strict tests of the SM.
• Measurements in different systems
provide complementary information.
• Moller Parity Violation can be measured
at JLab at a level which will impact the
Standard Model.
• DIS-Parity violation measurement is
easily carried out at JLab.
hep-ph/0205183
RPV
No SUSY
dark matter
17 January 2003
Paul E. Reimer, Argonne National Laboratory
Weak Mixing Angle MS-bar scheme
Jens Erler
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