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  • 21 July 2008 PREX Integrating Detector: Assessment and Plans 1

    Parity-Violating Mller Scattering

    Introduction and Meeting GoalsKrishna Kumar

    University of Massachusetts, Amherst

    August 14, 2008

    Mller Meeting

    Jefferson Laboratory

  • APV = mEGF2

    16 sin2 (3 + cos2 )2

    QeW

    21 July 2008 PREX Integrating Detector: Assessment and Plans

    Mller Scattering

    2

    Purely leptonic reaction

    APV meElab (1 4sin2W )

    1Elab

    Figure of Merit rises linearly with Elab

    (sin2W )sin2W

    0.05(APV )APV

    Small, well-understood dilution

    SLAC: Highest beam energy with moderate polarized luminosityJLab 11 GeV: Moderate beam energy with LARGE polarized luminosity

  • 15 May 2008 Probing the TeV-Scale with Parity-Violating Electron Scattering 3

    Comprehensive Search for New Neutral Current Interactions

    Many new physics models give rise to non-zero s at the TeV scale: Heavy Zs, compositeness, extra dimensions

    One goal of neutral current measurements at low energy AND colliders: Access > 10 TeV for as many f1f2 and L,R combinations as possible

    Important component of indirect signatures of new physics

    LEPII, Tevatron access scales s ~ 10 TeVe.g. Tevatron dilepton spectra, fermion pair production at LEPII

    - L,R combinations accessed are parity-conservingLEPI, SLC, LEPII & HERA accessed some parity-violating combinations but precision dominated by Z resonance measurements

    Lf1 f2 =4 ij2 ij

    i, j= L ,R f 1i f1i f 2 j f2 j

    Consider

    f1 f 1 f2 f 2

    f1 f2 f1 f2ors for all f1f2 combinations and L,R combinations

    Eichten, Lane and Peskin, PRL50 (1983)

  • 15 May 2008 Probing the TeV-Scale with Parity-Violating Electron Scattering 4

    Colliders vs Low Q2

    Window of opportunity for weak neutral current measurements at Q2

  • 15 May 2008 Probing the TeV-Scale with Parity-Violating Electron Scattering 5

    E158 New Physics Reach

    APV 4 109 Ebeam Pbeam

    ~ 10 ppb statistical error at highest Ebeam~ 0.4% error on weak mixing angle

  • 15 May 2008 Probing the TeV-Scale with Parity-Violating Electron Scattering 6

    E158 Result

    45 GeV: 14.0 revsg-2 spin precession

    48 GeV: 14.5 revs

    APV = (-131 14 10) x 10-9

    Phys. Rev. Lett. 95 081601 (2005)

  • +ee

    ee

    Z

    15 May 2008 Probing the TeV-Scale with Parity-Violating Electron Scattering 7

    Physics Implications

    0.001 0.01 0.1 1 10 100 1000

    Q [GeV]

    0.225

    0.230

    0.235

    0.240

    0.245

    0.250

    APVCesium

    SLAC E158Moller

    NuTeV

    !-DIS

    Z-pole

    sin

    2W

    Z"

    > (M

    )

    Erler and Ramsey-Musolf (2004) > 7 TeV

    > 16 TeV

    > 1 TeV

  • 0.231

    0.232

    0.233

    83.6 83.8 84 84.2

    68! CL

    !ll "MeV#

    sin

    2"

    lep

    t

    eff

    mt= 172.6 $ 1.4 GeV

    mH= 114...1000 GeV

    mt

    mH

    #$

    March 2008

    15 May 2008 Probing the TeV-Scale with Parity-Violating Electron Scattering

    Electroweak Constraints

    8

  • 15 May 2008 Probing the TeV-Scale with Parity-Violating Electron Scattering 9

    Precision sin2W at Any Scale

    mH = 89 +38-28 GeV S = -0.13 0.10

    ALR AFB (Z bb)

    sin2w = 0.2310(3)

    mH = 35 +26-17 GeVS= -0.11 17

    sin2w = 0.2322(3)

    mH = 480 +350-230 GeVS= +0.55 17

    Rules out the SM! Rules out SUSY!Favors Technicolor!

    Rules out Technicolor!Favors SUSY!

    (also APV in Cs) (also Moller @ E158)

    W. Marciano

    The Average: sin2w = 0.23122(17)

    3 apart

    Precision sin2W measurements at colliders very challengingNeutrino scattering cannot compete statisticallyNo resolution of this issue in next decade

    slide adapted from C. Kolda

  • 15 May 2008 Probing the TeV-Scale with Parity-Violating Electron Scattering 10

    Mller Scattering at 11 GeVParity-Violating Mller Scattering:Luminosity and Stability at Jlab upgrade makes feasible a factor of 5 improvement over E158

    sin2W to 0.00025ee ~ 25 TeV reach

    Best new measurement until Linear Collider or Neutrino Factory

    E158-like Quad concept: same quads provide focus; fits within 25 m

    A possible toroid design with better acceptance is being investigated

    L. Mercado

    (Aexp) = 0.6 ppb!

    Rate ~ 200 GHz!

    Mother of all PV measurements!

  • 15 May 2008 Probing the TeV-Scale with Parity-Violating Electron Scattering 11

    Constraining New PhysicsDoes Supersymmetry (SUSY) provide a candidate for dark matter?Neutralino is stable if baryon (B) and lepton (L) numbers are conservedB and L need not be conserved (RPV): neutralino decay

    Kurylov, Ramsey-Musolf, SuRPC SUSY

    RPV SUSY

    Qweak

    12 GeV Mller

    12 GeV Mller

    PVDIS

    Qweak, PVDIS and Mller measurements are complementary

    Model-dependent constraints on new particles: e.g. Z bosons ~ 2.5 TeV Should LHC see anomalies, such measurements extremely valuable

  • 15 May 2008 Probing the TeV-Scale with Parity-Violating Electron Scattering

    Community Endorsement

    12 GeV Science Review Well-attended workshop Dec 06 High profile in Long Range Plan Steering Committee formed:

    R. Carlini, G. Cates, K. Kumar, D. Mack, P. Souder, W. van Oers

    12

  • 15 May 2008 Probing the TeV-Scale with Parity-Violating Electron Scattering 13

    E158 Design ~ 1997 10 nm control of beam centroid on target

    R&D on polarized source laser transport elements

    12 microamp beam current maximum 1.5 meter Liquid Hydrogen target

    20 Million electrons per pulse @ 120 Hz 200 ppm pulse-to-pulse statistical fluctuations

    Electronic noise and density fluctuations < 10-4

    Pulse-to-pulse monitoring resolution ~ 1 micron Pulse-to-pulse beam fluctuations < 100 microns

    100 Mrad radiation dose from scattered flux State-of-the-art radiation-hard integrating calorimeter

    Full Azimuthal acceptance with lab ~ 5 mrad Quadrupole spectrometer

    Novel design that enclosed primary & scattered beam inside magnets

    Complex collimation and radiation shielding issues Precision alignment, water cooling and radiation protection

  • 21 July 2008 PREX Integrating Detector: Assessment and Plans

    11 GeV JLab Challenges

    14

    1 nm control of beam centroid on target R&D on polarized source laser transport elements

    85 microamp beam current maximum 1.5 meter Liquid Hydrogen target: 5-6 kW!!

    200 GHz Rate Must flip Pockels cell ~ 1 kHz: more R&D needed

    50 ppm pulse-to-pulse statistical fluctuations Electronic noise and density fluctuations < 10-5

    Pulse-to-pulse monitoring resolution ~ 100 nm!

    Full Azimuthal acceptance with lab ~ 5 mrad aggressive spectrometer design

    Quadrupole design a la E158 New 100% azimuthal acceptance toroids

    Complex collimation and radiation shielding issues Precision alignment, water cooling and radiation protection

  • 21 July 2008 PREX Integrating Detector: Assessment and Plans

    Statistical Error Critical

    15

  • 21 July 2008 PREX Integrating Detector: Assessment and Plans

    Progress to Date

    Spectrometer Design Quadrupole

    proof of principle first attempt at detector placement and collimation

    Toroids novel 100% acceptance first attempt at ray traces and field characteristics

    Spectrometer choice drives everything else

    16

  • 21 July 2008 PREX Integrating Detector: Assessment and Plans

    Near-Term Plans Run simulations on two spectrometer

    options: Collimation Backgrounds Statistical Error

    Initiate formation of collaboration Assign tasks for LOI/Proposal

    preparation

    17

  • 21 July 2008 PREX Integrating Detector: Assessment and Plans

    Meeting Goals

    Lay out technical challenges Assign tasks to address them Estimate statistical error LOI or Proposal? Timeline for document Next meeting?

    18