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Electroweak Physics at an Electron-Ion Collider

Electroweak Physics at an Electron-Ion Collider. M.J. Ramsey-Musolf Wisconsin-Madison. NPAC. Theoretical Nuclear, Particle, Astrophysics & Cosmology. http://www.physics.wisc.edu/groups/particle-theory/. ECT* Trento, July 2008. Outline. Brief Context: Precision and Energy Frontiers

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Electroweak Physics at an Electron-Ion Collider

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  1. Electroweak Physics at an Electron-Ion Collider M.J. Ramsey-Musolf Wisconsin-Madison NPAC Theoretical Nuclear, Particle, Astrophysics & Cosmology http://www.physics.wisc.edu/groups/particle-theory/ ECT* Trento, July 2008

  2. Outline • Brief Context: Precision and Energy Frontiers • Neutral Current Processes: PV DIS & PV Moller • Charged Current Processes: e-+AK ET + j • Lepton flavor violation: e-+AK  - + A Disclaimer: some ideas worked out in detail; others need more research

  3. Low-Energy: What we have learned • Weak interactions violate P • QCD is tiny • QWP ~ 0.1 QWn ~ -1 • S-quarks: impt for spin, not for N • Sin2W runs • TeV scale technicolor unlikely • Nuclei have large anapole moments

  4. What we would like to know • Does the “new SM” violate CP? Can it explain the abundance of matter? • Are there new TeV scale interactions? If so, what are their symmetries? • How does QCD make a proton? • Are lepton number and charged lepton flavor conserved ?

  5. Electroweak symmetry breaking: Higgs ? ? Low-energy: precision frontier LHC: energy frontier EIC: Post LHC Era Beyond the SM SM symmetry (broken) Precision Probes of New Symmetries New Symmetries Origin of Matter Unification & gravity Weak scale stability Neutrinos

  6. Probing Fundamental Symmetries beyond the SM: Use precision low-energy measurements to probe virtual effects of new symmetries & compare with collider results • Precision measurements predicted a range for mt before top quark discovery • mt >> mb ! • mt is consistent with that range • It didn’t have to be that way • Precision Frontier: • Precision ~ Mass scale • Look for pattern from a variety of measurements • Identify complementarity with collider searches • Special role: SM suppressed processes Radiative corrections Direct Measurements Stunning SM Success Precision & Energy Frontiers J. Ellison, UCI

  7. Muons • gm-2 • mA->eA • EIC: • More PV • New CC ? • LFV ? Nuclei & Charged Leptons PV Electron Scattering • Q-Weak • 12 GeV Moller • PV DIS Weak Decays • n decay correlations • nuclear b decay • pion decays • muon decays

  8. Neutral Current Probes: PV • Basics of PV electron scattering • Standard Model: What we know • New physics ? SUSY as illustration • Probing QCD

  9. “Weak Charge” ~ 0.1 in SM Enhanced transparency to new physics Small QCD uncertainties (Marciano & Sirlin; Erler & R-M) QCD effects (s-quarks): measured (MIT-Bates, Mainz, JLab) PV Electron Scattering Parity-Violating electron scattering

  10. Muons Weak Decays • gm-2 • mA->eA • n decay correlations • nuclear b decay • pion decays • muon decays • Essential Role for Theory • Precise SM predictions (QCD) • Sensitivity to new physics & complementarity w/ LHC Nuclei & Charged Leptons: Theory PV Electron Scattering • Q-Weak • 12 GeV Moller • PV DIS • Substantially reduced QCD uncertainty in sin2qW running • QCD uncertainties in ep box graphs quantified • Comprehensive analysis of new physics effects

  11. Weak Charge: Nu C1u + Nd C1d Proton: QWP = 2 C1u + C1d = 1-4 sin2W ~ 0.1 Electron: QWe = C1e = -1+4 sin2W ~ - 0.1 Effective PV e-q interaction & QW Low energy effective PV eq interaction

  12. Flavor-dependent Large logs in  Sum to all orders with running sin2W & RGE sin2 Normalization Scale-dependent effective weak mixing Constrained by Z-pole precision observables Flavor-independent QW and Radiative Corrections Tree Level Radiative Corrections

  13. SU(2)L U(1)Y Weak Charge & Weak Mixing Weak mixing depends on scale

  14. SLAC Moller Z0 pole tension Parity-violating electron scattering Scale-dependence of Weak Mixing Weak Mixing in the Standard Model

  15. W. Marciano Z Pole Tension The Average: sin2θw = 0.23122(17) ⇒ mH = 89 +38-28 GeV ⇒ S = -0.13 ± 0.10 3σ apart Rules out Technicolor! Favors SUSY! ALR AFB (Z→ bb) (also APV in Cs) (also Moller @ E158) sin2θw = 0.2322(3) ↓ mH = 480 +350-230 GeV S= +0.55 ± 17 sin2θw = 0.2310(3) ↓ mH = 35 +26-17 GeV S= -0.11 ± 17 Rules out SUSY! Favors Technicolor! Rules out the SM! • Precision sin2W measurements at colliders very challenging • Neutrino scattering cannot compete statistically • No resolution of this issue in next decade K. Kumar

  16. JLab Future SLAC Moller Z0 pole tension Parity-violating electron scattering Scale-dependence of Weak Mixing Weak Mixing in the Standard Model

  17. Weak Charge: Nu C1u + Nd C1d Proton: QWP = 2 C1u + C1d = 1-4 sin2W ~ 0.1 Electron: QWe = C1e = -1+4 sin2W ~ - 0.1 Effective PV e-q interaction & PVDIS Low energy effective PV eq interaction PV DIS eD asymmetry: leading twist

  18. Model Independent Constraints P. Reimer, X. Zheng

  19. Like QWp,e ~ 1 - 4 sin2qW Flavor-dependent Normalization Scale-dependent effective weak mixing Constrained by Z-pole precision observables Flavor-independent C2q and Radiative Corrections Tree Level Radiative Corrections

  20. QWP = 0.0716 QWe = 0.0449 Experiment SUSY Loops E6 Z/ boson RPV SUSY Leptoquarks SM SM New Physics: Comparing PV Observables

  21. Vertex & External leg Kurylov, RM, Su SUSY Radiative Corrections Propagator Box

  22. No SUSY DM: LSP unstable • Neutrinos are Majorana 12k 1j1 12k 1j1 L=1 L=1 SUSY: R Parity-Violation

  23. Moller (ee) RPV: No SUSY DM Majorana n s SUSY Loops Q-Weak (ep) d QWP, SUSY / QWP, SM d QWe, SUSY / QWe, SM Hyrodgen APV or isotope ratios gm-2 12 GeV 6 GeV E158 Global fit: MW, APV, CKM, l2,… Kurylov, RM, Su PVES & APV Probes of SUSY

  24. e RPV Loops p Comparing AdDIS and Qwp,e

  25. Higher Twist: qq and qqg correlations e- e- * Z* X N Charge sym in pdfs d(x)/u(x): large x Electroweak test: e-q couplings & sin2qW Deep Inelastic PV: Beyond the Parton Model & SM

  26. Higher Twist (J Lab) CSV (J Lab, EIC) d/u (J Lab, EIC) + PVDIS & QCD Low energy effective PV eq interaction PV DIS eD asymmetry: leading twist

  27. Londergan & Murdock PVDIS & CSV • Direct observation of parton-level CSV would be very exciting! • Important implications for high energy collider pdfs • Could explain significant portion of the NuTeV anomaly Few percent A/A Adapted from K. Kumar

  28. SU(6): d/u~1/2 Valence Quark: d/u~0 Perturbative QCD: d/u~1/5 PVDIS & d(x)/u(x): xK1 Adapted from K. Kumar A/A ~ 0.01 Very sensitive to d(x)/u(x) PV-DIS off the proton (hydrogen target)

  29. JLab Future SLAC Moller EIC PVDIS ? Z0 pole tension EIC Moller ? Parity-violating electron scattering Scale-dependence of Weak Mixing PVES at an EIC

  30. Charged Current Processes • The NuTeV Puzzle • HERA Studies • W Production at an EIC ? CC/NC ratios ?

  31. JLab Future SLAC Moller Z0 pole tension nucleus deep inelasticscattering Scale-dependence of Weak Mixing Weak Mixing in the Standard Model

  32. SUSY Loops Wrong sign RPV SUSY The NuTeV Puzzle Paschos-Wolfenstein

  33. Other New CC Physics? Low-Energy Probes Nuclear & neutron decay O / OSM ~ 10-3 Pion leptonic decay O / OSM ~ 10-4 O / OSM ~ 10-2 Polarized -decay HERA W production O / OSM ~ 10-1 A. Schoning (H1, Zeus)

  34. Lepton Number & Flavor Violation • LNV & Neutrino Mass • Mechanism Problem • LFV as a Probe • K e Conversion at EIC ?

  35. mnEFF & neutrino spectrum Theory Challenge: matrix elements+ mechanism Long baseline b-decay ? Normal Inverted ? 0nbb-Decay: LNV? Mass Term? Dirac Majorana

  36. mnEFF & neutrino spectrum See-saw mechanism Theory Challenge: matrix elements+ mechanism H H nL nR nL Leptogenesis Long baseline b-decay ? Lepton Asym ! Baryon Asym Normal Inverted GERDA CUORE EXO Majorana ? 0nbb-Decay: LNV? Mass Term? Dirac Majorana

  37. Theory Challenge: matrix elements+ mechanism Does operator power counting suffice? Prezeau, R-M, Vogel: EFT O(1) for L ~ TeV 0nbb-Decay: Mechanism Dirac Majorana Mechanism: does light nM exchange dominate ? How to calc effects reliably ? How to disentangle H & L ?

  38. 0nbb signal equivalent to degenerate hierarchy Loop contribution to mn of inverted hierarchy scale 0nbb-Decay: Interpretation

  39. Present universe Early universe ? ? Bm->e R = Bm->eg Weak scale Planck scale Lepton Flavor & Number Violation MEG: Bmeg ~ 5 x 10-14 2e: Bm->e ~ 5 x 10-17 Also PRIME

  40. 0nbb decay m “naturalness”: Light nM exchange ? m->eg m->e LFV Probes of RPV: LFV Probes of RPV:  : Heavy particle exchange ? lk11/ ~ 0.09 for mSUSY ~ 1 TeV lk11/ ~ 0.008 for mSUSY ~ 1 TeV Low scale LFV: R ~ O(1) GUT scale LFV: R ~ O(a) Lepton Flavor & Number Violation Raidal, Santamaria; Cirigliano, Kurylov, R-M, Vogel MEG: Bm->eg ~ 5 x 10-14 Logarithmic enhancements of R 2e: Bm->e ~ 5 x 10-17

  41. BKe48 |A2e|2 |A2e|2 < 10-8 If |A1e|2 ~ |A2e|2 EIC:  ~ 10-5 fb Log enhancement: |A1e|2 / |A2e|2 ~ | ln me / 1 TeV |2 ~ 100 Logarithmic enhancements of R Lepton Flavor & Number Violation Raidal, Santamaria; Cirigliano, Kurylov, R-M, Vogel Exp: B->eg ~ 1.1 x 10-7 Need ~ 1000 fb EIC:  ~ 103 | A1e|2 fb

  42. qq eff op LFV with  leptons: HERA Induce Keat one loop? Leptoquark Exchange lq|2 < 10-4 (MLQ / 100 GeV)2 Veelken (H1, Zeus) (2007)

  43. qq eff op lq|2 < 2 x 10-2 (MLQ / 100 GeV)2 LFV with  leptons: recent theory Kanemura et al (2005) SUSY Higgs Exchange lq|2 < 10-4 (MLQ / 100 GeV)2 HERA

  44. Summary • Precision studies and symmetry tests are poised to discovery key ingredients of the new Standard Model during the next decade • There may be a role for an EIC in the post-LHC era • Promising: PV Moller & PV DIS for neutral currents • Homework: Charged Current probes -- can they complement LHC & low-energy studies? • Intriguing: LFV with eK conversion:

  45. Thank you ! To the organizers, ECT* staff, and participants for a lively and stimulating workshop • Precision studies and symmetry tests with neutrons are poised to discovery key ingredients of the new Standard Model during the next decade • Physics “reach” complements and can even exceed that of colliders: dn~10-28 e-cm ; O/OSM ~ 10-4 • Substantial experimental and theoretical progress has set the foundation for this era of discovery • The precision frontier is richly interdisciplinary: nuclear, particle, hadronic, atomic, cosmology

  46. Back Matter • Precision studies and symmetry tests with neutrons are poised to discovery key ingredients of the new Standard Model during the next decade • Physics “reach” complements and can even exceed that of colliders: dn~10-28 e-cm ; O/OSM ~ 10-4 • Substantial experimental and theoretical progress has set the foundation for this era of discovery • The precision frontier is richly interdisciplinary: nuclear, particle, hadronic, atomic, cosmology

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