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RHIC-Spin and Lorentz Structure of Electroweak Current

RHIC-Spin and Lorentz Structure of Electroweak Current. Introduction Brief review of the current status RHIC-Spin sensitivity to quark dipole moments Conclusion. V. L. Rykov May 15, 2001. SPIN PHYSICS AT RHIC IN YEAR-1 AND BEYOND RIKEN-BNL Workshop. Introduction.

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RHIC-Spin and Lorentz Structure of Electroweak Current

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  1. RHIC-Spin and Lorentz Structure of Electroweak Current • Introduction • Brief review of the current status • RHIC-Spin sensitivity to quark dipole moments • Conclusion V. L. Rykov May 15, 2001 SPIN PHYSICS AT RHIC IN YEAR-1 AND BEYOND RIKEN-BNL Workshop

  2. Introduction • Lorentz structure of electroweak interactions has always been and remains tobe the focus of many precise nuclear and particle physics experiments. • Much attentions is paid to test the universality of the electroweakinteraction, ingeneral, and to evaluating electroweak dipole moments of leptons and quarks, in particular. • The current experimental constraints to magnetic and electricdipole momentsof -lepton and quarks are still far from the values, predicted in the SM. • If any of these moments were found nonzero and above SM’sexpectations, thiswould be a clear signal of a New Physics beyond SM. • Will RHIC-Spin be able to contribute something useful to this study? V. L. Rykov May 15, 2001 SPIN PHYSICS AT RHIC IN YEAR-1 AND BEYOND RIKEN-BNL Workshop

  3. (Still)Introduction , g, Z, W, h, … f f • Theory: PDG; T. Kinoshita et al (1981);A. Czarnecki et al (1998); J. Bernabeu et al (1995);K. Babu et al (2000) • Experimental limits: q2 = 0 :PDG;P. Mohr et al (1999);H. Brown et al (2001);L3 (1998); T. Escribano et al (1994,’97) q2 = MW2:L3 (1998); OPAL (1997); SLD (1999); R. Escribano et al (1993,’94, ’97); G. Gonzalez-Sprinberg et al (2000); J. Weinstein (1999) V. L. Rykov May 15, 2001 SPIN PHYSICS AT RHIC IN YEAR-1 AND BEYOND RIKEN-BNL Workshop

  4. Magnetic Moments of Leptons and Quarks at q2=0 Scaling with fermion mass V. L. Rykov May 15, 2001 SPIN PHYSICS AT RHIC IN YEAR-1 AND BEYOND RIKEN-BNL Workshop

  5. Magnetic Moments of Leptons and Quarks at Scaling withq2 Natural energy scale V. L. Rykov May 15, 2001 SPIN PHYSICS AT RHIC IN YEAR-1 AND BEYOND RIKEN-BNL Workshop

  6. RHIC sensitivity to - quark and lepton momenta - quark polarization âqqN,T  2 ; AppN,T  âqqN,T /2   P  70% RHIC-500: S = 500 GeV; L = 800 pb-1/year NW ~ 1.3·105/year; NZ ~ 5·103/year RHIC-650: S = 650 GeV; L = 20 fb-1/year NW ~ 7·106/year; NZ ~ 2.5·105/year V. L. Rykov May 15, 2001 SPIN PHYSICS AT RHIC IN YEAR-1 AND BEYOND RIKEN-BNL Workshop

  7. CP- and T-violating “electric” dipole moments Current limits fordu,d: du,d (q2 = 0) < (1-4)·10-25 e·cm - A. De Rujula et al (1991) du,d (q2 = MZ2) < 1.8·10-16 e·cm - T. Escribano et al (1994) dwu,d (q2 = MZ2) < 3.4·10-17 e·cm - T. Escribano et al (1994) RHIC-650: dwu,d (q2 = MW2) < 5·10-19 e·cm Implications for dn(q2 = 0) (current limit < 6.3·10-26e·cm) : dn (dwu,d = 5·10-19 e·cm) ~ from 3·10-24to 4·10-26 e·cm(???) p p W n n ? V. L. Rykov May 15, 2001 SPIN PHYSICS AT RHIC IN YEAR-1 AND BEYOND RIKEN-BNL Workshop

  8. Conclusion • The measurements of lepton single-spin transverse • asymmetries in W and Z production at RHIC with polarized • protons will allow to improve the current limits on • electroweak dipole moments of u and d quarks by a factor • of ~10-100 at the energy scale of MW,Z. • While RHIC-Spin sensitivity will not be sufficient to detect • nonzero dipole moments, induced due to SM interactions, • an observation of a nonzero single-spin asymmetry would • be a clear indication of a New Physics beyond SM. V. L. Rykov May 15, 2001 SPIN PHYSICS AT RHIC IN YEAR-1 AND BEYOND RIKEN-BNL Workshop

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