Symmetries in Nuclear Physics Krishna Kumar University of Massachusetts Editorial Board: Parity Violation: K. K, D. Mack, M. Ramsey-Musolf, P. Reimer, P. Souder Low Energy QCD: B. Bernstein, A. Gasparian, J. Goity Jlab 12 GeV PAC Meeting, January 10, 2005 10 January, 2005 Symmetries in Nuclear Physics

Symmetries in Nuclear Physics Symmetry Tests at 12 GeV Strong Interaction Chiral symmetry breaking Axial Anomaly Charge symmetry violation Spin-Flavor symmetry breaking Electroweak Interaction TeV scale physics 10 January, 2005 Symmetries in Nuclear Physics

Symmetries in Nuclear Physics Outline Primakoff Production of Pseudoscalar Mesons 2 decay widths of  and ’ Transition Form Factors at low Q2 Parity-Violating Møller Scattering Ultimate Precision at Q2<<MZ2: 25 TeV reach Parity-Violating Deep Inelastic Scattering New Physics at 10 TeV in Semileptonic Sector Charge Symmetry Violation d/u at High x Higher Twist Effects 10 January, 2005 Symmetries in Nuclear Physics

Lightest Pseudoscalar Mesons Spontaneous breaking of Chiral SUL(3)xSUR(3) Goldstone bosons Chiral anomalies - Mass of 0 - 2 decay widths Flavor SU(3) breaking π0, , ’ mixing Test fundamental QCD symmetries via the Primakoff Effect 10 January, 2005 Symmetries in Nuclear Physics

Setup with Energy Upgrade Larger X-Section Lighter Nuclei: 1H and 4He Better background separation New high energy photon tagger Improved PbWO4 calorimeter 10 January, 2005 Symmetries in Nuclear Physics

From 2 to 3π to Quark Mass Ratio Leutwyler 10 January, 2005 Symmetries in Nuclear Physics

Symmetries in Nuclear Physics Major Physics Impact Determination of quark mass ratio The nature of the ’: Goldstone boson? Interaction Radii of π0, , ’ Chiral anomaly predictions Number of colors Nc Tests of QCD models Tests of future lattice calculations Input to light-by-light amplitude for (g-2) 10 January, 2005 Symmetries in Nuclear Physics

Symmetries in Nuclear Physics PV Asymmetries to (gAegVT + gVegAT) For electrons scattering off nuclei or nucleons: Z couplings provide access to different linear combination of underlying quark substructure 10 January, 2005 Symmetries in Nuclear Physics

Parity Violation at Jlab Electron Beam Quality Simple laser transport system; pioneers in PV experiments with high polarization cathodes (HAPPEX-I) CW beam alleviates many higher order effects; especially in energy fluctuations HAPPEX-II preliminary result: Araw correction ~ 60 ppb High Luminosity High beam current AND high polarization Dense cryogenic targets with small density fluctuations Progression of Precision Experiments Facilitates steady improvements in technology Strong collaboration between accelerator and physics divisions (APV)/APV 1% (APV) 1 part per billion 10 January, 2005 Symmetries in Nuclear Physics

The Annoying Standard Model (it just wont break!) The Annoying Standard Model Nuclear Physics Long Range Plan: What is the new standard model? Low Q2 offers unique and complementary probes of new physics Rare or Forbidden Processes Symmetry Violations Electroweak One-Loop Effects - Double beta decay.. - neutrinos, EDMs.. - Muon g-2, beta decay.. Precise predictions at level of 0.1% Indirect access to TeV scale physics Low energy experiments are again relevant in the neutral current sector 10 January, 2005 Symmetries in Nuclear Physics

World Electroweak Data 16 precision electroweak measurements: 2/dof ~ 25.4/15 Probability < 5% Leptonic and hadronic Z couplings seem inconsistent Perhaps the Standard Model is already broken Perhaps there are bigger effects elsewhere 10 January, 2005 Symmetries in Nuclear Physics

Electroweak Physics at Low Q2 Q2 << scale of EW symmetry breaking Logical to push to higher energies, away from the Z resonance LEPII, Tevatron, LHC access scales greater than L ~ 10 TeV Q2<<MZ2 Complementary: Parity Violating vs Parity Conserving 10 January, 2005 Symmetries in Nuclear Physics

Fixed Target Møller Scattering Purely leptonic reaction QWe ~ 1 - 4sin2W Figure of Merit rises linearly with Elab Maximal at 90o in COM (E’=Elab/2) Highest possible Elab with good P2I Moderate Elab with LARGE P2I SLAC E158 Jlab at 12 GeV Unprecedented opportunity: The best precision at Q2<<MZ2 with the least theoretical uncertainty until the advent of a linear collider or a neutrino factory 10 January, 2005 Symmetries in Nuclear Physics

Symmetries in Nuclear Physics Design for 12 GeV E’: 3-6 GeV APV = 40 ppb lab = 0.53o-0.92o 150 cm LH2 target 4000 hours Ibeam = 100 µA Toroidal spectrometer ring focus (APV)=0.58 ppb Beam systematics: steady progress (E158 Run III: 3 ppb) Focus alleviates backgrounds: ep  ep(), ep  eX() Radiation-hard integrating detector Normalization requirements similar to other planned experiments Cryogenics, density fluctuations and electronics will push the state- of-the-art 10 January, 2005 Symmetries in Nuclear Physics

Symmetries in Nuclear Physics New Physics Reach Jlab Møller LHC ee ~ 25 TeV New Contact Interactions Complementary; 1-2 TeV reach LEP200 ee ~ 15 TeV SUSY provides a dark matter candidate if baryon (B) and lepton (L) numbers are conserved Kurylov, Ramsey-Musolf, Su However, B and L need not be conserved in SUSY, leading to neutralino decay (RPV) QeW and QpW would have new contributions from RPV 10 January, 2005 Symmetries in Nuclear Physics

Symmetries in Nuclear Physics Electroweak Physics QWe modified Marciano and Czarnecki sin2W runs with Q2 Semileptonic processes have significant uncertainties E158 established running, probing vector boson loops Jlab measurement would probe scalar loops (sin2W) ~ 0.0003 10 January, 2005 Symmetries in Nuclear Physics

Parity Violating Electron DIS Z* * X N fi(x) are quark distribution functions For an isoscalar target like 2H, structure functions largely cancel in the ratio + small corrections b(x) is a factor of 5 to 10 smaller Elastic scattering measures C1i, but C2i are less well-known 12 GeV: Moderate x, high Q2, W2 1% measurements feasible TeV scale physics 10 January, 2005 Symmetries in Nuclear Physics

Symmetries in Nuclear Physics 2H PV DIS at 11 GeV E’: 6.8 GeV ± 10% APV = 290 ppm lab = 12.5o 400 hours Ibeam = 90 µA 60 cm LD2 target xBj ~ 0.45 Q2 ~ 3.5 GeV2 W2 ~ 5.23 GeV2 1 MHz DIS rate, π/e ~ 1 HMS+SHMS or MAD (APV)=1.5 ppm Systematic limit: Beam polarization Beam systematics easily controlled moderate running time Best constraint on 2C2u-C2d Similar sensitivity to NuTeV Theoretical interpretability issues: Important in themselves! PV DIS can address these issues 10 January, 2005 Symmetries in Nuclear Physics

Charge Symmetry Violation (CSV) Charge symmetry: assume are negligible u-d mass difference electromagnetic effects Small effects are possible from: Search for unambiguous signal of CSV at the partonic level No theoretical issues at high Q2, W2 For PV DIS off 2H: 10% effect possible if u+d falls off more rapidly than u-d at x ~ 0.7 From pdf fits: 1/3 of NuTeV discrepancy from CSV But at 90% C.L., effect could be 3 to 4 times bigger…. Londergan & Thomas Strategy for PV DIS: measure or constrain higher twist effects at x ~ 0.5-0.6 precision measurement of APV at x ~ 0.7 to search for CSV 10 January, 2005 Symmetries in Nuclear Physics

Symmetries in Nuclear Physics Higher Twist Effects Brodsky  APV sensitive to diquarks: ratio of weak to electromagnetic charge depends on amount of coherence If Spin 0 diquarks dominate, likely only 1/Q4 effects. Novel interference terms might contribute Other higher twist effects may cancel, so APV may have little dependence on Q2. 10 January, 2005 Symmetries in Nuclear Physics

Symmetries in Nuclear Physics d/u at High x SU(6) breaking (scalar diquark dominance), expect d/u ~ 0 Perturbative QCD prediction for x ~ 1: d/u ~ 0.2 No consensus on existing deuteron structure function data Proposed methods have nuclear corrections APV in DIS on 1H + small corrections d/u measurement on a single proton! No nuclear corrections! Must control higher twist effects Verify Standard Model at low x Must obtain ~ 1% stat. errors at x ~ 0.7 10 January, 2005 Symmetries in Nuclear Physics

Symmetries in Nuclear Physics PV DIS Program Hydrogen and Deuterium targets 1 to 2% errors It is unlikely that any effects are larger than 10% x-range 0.3-0.7 W2 well over 4 GeV2 Q2 range a factor of 2 for each x point (Except x~0.7) Moderate running times TeV physics, higher twist probe, CSV probe, precision d/u… The Standard Model test can be done with proposed Hall upgrade equipment A dedicated spectrometer/detector package is needed for rest of program 10 January, 2005 Symmetries in Nuclear Physics

A Concept for PV DIS Studies Magnetic spectrometer would be too expensive Calorimeter to identify electron clusters and reject hadrons a la A4 at Mainz Toroidal sweeping field to reduce neutrals, low energy Mollers and pions Cherenkov detectors for pion rejection might be needed CW 100 µA at 11 GeV 20 to 40 cm LH2 and LD2 targets Luminosity > 1038/cm2/s solid angle > 200 msr Count at 100 kHz pion rejection of 102 to 103 10 January, 2005 Symmetries in Nuclear Physics

Symmetries in Nuclear Physics High x Physics Outlook Parity-Violating DIS can probe exciting new physics at high x One can start now (at 6 GeV) Do 2 low Q2 points (P-05-007, X. Zheng contact) Q2 ~ 1.1 and 1.9 GeV2 Either bound or set the scale of higher twist effects Take data for W<2 (P-05-005, P. Bosted contact) Duality Could help extend range at 11 GeV to higher x A short run to probe TeV physics in PV DIS off 2H: Hall A or C The bulk of the program requires a dedicated spectrometer/detector CSV can also be probed via electroproduction of pions 6 GeV beam can probe x ~ 0.45 (P-05-006, K. Hafidi contact) Should be able to go to higher x with 12 GeV beam Other physics topics could be addressed: Transverse (beam-normal) asymmetries in DIS Polarized targets: g2 and g3 structure functions Higher twist studies of A1p and A1n 10 January, 2005 Symmetries in Nuclear Physics

Symmetries in Nuclear Physics Summary New window to symmetry tests opened by 12 GeV upgrade Precision measurements of pseudoscalar meson properties: tests of low energy QCD and extraction of fundamental parameters APV in Møller scattering has unique sensitivity to leptonic contact interactions to 25 TeV APV in DIS off 2H at x ~ 0.45 would probe for TeV physics in axial-vector quark couplings An exciting array of important topics in high x physics can be addressed by a new, dedicated spectrometer/detector concept 10 January, 2005 Symmetries in Nuclear Physics