Paul E. ReimerArgonne National Laboratory
17 January 2003
Exploring the Standard Model with JLab at 12 GeV
• Standard Model tests: Beyond sin2(W).
• e2ePV: Moller Scattering at 11 GeV
• DIS-Parity: Parity NonConserving Electron Deep Inelastic Scattering
For Dave Mack, Paul Souder, Michael Ramsey-Musolf, et al.
17 January 2003 Paul E. Reimer, Argonne National Laboratory 2
sin2(W) measurements below Z-pole
• Atomic Parity Violation (APV):– Hard to understand theoretically.– Consistent with S.M. (plot is out of date)
Future measurements
• Qweak (Jlab)– Qweak PROTON– ¼ 2005-07
• E158-Moller– QWeak ELECTRON– Final run 2003
•e2ePV–11 GeV-Moller Scattering–Q2 = 0.008 GeV2.
•DIS-Parity–11 GeV JLab DIS Parity Violation–Q2 = 3.5 GeV2
• Standard Model predicts sin2(W) 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 A scattering:– 3 from Standard Model!!!– Fe target: PDF’s in iron? Nuclear corrections?
17 January 2003 Paul E. Reimer, Argonne National Laboratory 3
RPVRPV
No SUSY No SUSY dark dark mattermatter
Beyond sin2(W): e.g. SUSY and Dark Matter
What is Dark Matter? •S.M.: QW
electron and QWproton both
measure 1-4sin2(W).•SUSY: Loop contributions can change this by measurable amounts!
NASA Hubble NGC3310
hep-ph/0205183
JLab QWeak (proton) and SLAC E158
Moller (QWe)
anticipated limits.
17 January 2003 Paul E. Reimer, Argonne National Laboratory 4
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 5
e2ePV: Moller Scattering at 12 GeV
• Measurement of QWeak of the electron.
• Very small asymmetry:
A|11 GeV ¼ 9¢10-7 (1 – 4 sin2W) 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 6
Moller sin2 W Error De-Magnification
sin2(W) ¼ 0.2381 - 4 sin2(W) ¼ 0.05
Radiative corrections• Not all of which are suppressed (De-Magnified) by (1-4sin2(W)• Reduce tree-level Moller asymmetry by ¼ 40%
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Moller 12 GeV vs. 48 GeV
Repeat SLAC-E158 Moller
• Figure of merit:• A2 d/d / 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.
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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 9
Moller sin2(W) Anticipated Uncertainties
Clearly a competitive measurement of sin2W 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 10
Moller Detection
Detector Concept:• Drift scattered electrons to a collimator.• Focus electrons in a resistive toroidal
magnet.• Drift electrons to detector ring.
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 Paul E. Reimer, Argonne National Laboratory 11
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. RPVRPV
No SUSY No SUSY dark matterdark matter
hep-ph/0205183
JLab QWeak (proton) and JLab e2ePV
Moller (QWe)
anticipated limits.
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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 13
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 A vs. 4 A at SLAC in ’78 £ 25 stat• 60 cm target vs. 30 cm target £ 2 stat• Pe (=electron polarization) = 80% vs. 37% £ 4 stat• Pe ¼ 1% vs. 6% £ 6 sys
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DIS-Parity: Polarized e- deuterium DISLongitudinally polarized electrons on unpolarized isoscaler (deuterium) target.
Note that each of the Cia are sensitive to different possible S.M.
extensions.
C1q ) NC vector coupling to q £ NC axial coupling to eC2q ) NC axial coupling to q £ NC vector coupling to e
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DIS-Parity: Detector and Expected Rates• Expt. Assumptions:
– 60 cm ld2/lH2 target– 11 GeV beam @ 90– 75% polar.– 12.5± central angle– 12 msr d– 6.8 GeV§10% mom. bite
• Rate expectations:– ¼ 1MHz DIS– /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.
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Uncertainties in Ad• Beam Polarization:
–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%
Q2 0.5%
Radiative corr. <1%
R = (L/T) = § 15% <0.02%
s(x) = § 10% <0.03%
EMC Effect ????
Higher Twist ????
What about Ciq’s?
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Extracted Signal—It’s all in the binning
Note—Polarization uncertainty enters as in slope and intercept
Aobs = PAd / P(2C1u–C1d) + P(2C2u–C2d)Y]
but is correlated
PDG: C1u= –0.209§0.041 highlyC1d= 0.358§0.037
correlated
2C2u– C2d = –0.08§0.24
This measurement:
(2C1u– C1d) = 0.005 (stat.)
(2C2u– C2d) = 0.014 (stat.)
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DIS-Parity determines 2C2u-C2d
Combined result significantly constrains 2C2u–C2d. PDG 2C2u–C2d = –0.08 § 0.24 Combined (2C2u–C2d) = § 0.014
£ 17 improvement (S.M 2C2u – C2d = 0.0986)
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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.
• Higher twist may be important
(2C1u – C1d) = 0.005(2C2u – C2d) = 0.014
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JLab tests of the Standard Model • Measurements of sin2(W) 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.
RPVRPV
No SUSY No SUSY dark matterdark matter
hep-ph/0205183
Weak Mixing Angle MS-bar schemeJens Erler