Sub Z Supersymmetry Precision Electroweak Studies in Nuclear Physics M.J. Ramsey-Musolf NSAC Long Range Plan • What is the structure of the nucleon? • What is the.
Download ReportTranscript Sub Z Supersymmetry Precision Electroweak Studies in Nuclear Physics M.J. Ramsey-Musolf NSAC Long Range Plan • What is the structure of the nucleon? • What is the.
Sub Z Supersymmetry Precision Electroweak Studies in Nuclear Physics M.J. Ramsey-Musolf NSAC Long Range Plan • What is the structure of the nucleon? • What is the structure of nucleonic matter? • What are the properties of hot nuclear matter? • What is the nuclear microphysics of the universe? • What is to be the new Standard Model? Neutrino physics Precision measurements: -decay, -decay, parity violating electron scattering, EDM’s… What can they teach us about the new Standard Model? The Standard Model of particle physics is a triumph of late 20th century physics • It provides a unified framework for 3 of 4 (known) forces of nature in context of renormalizable gauge theory The Standard Model of particle physics is a triumph of late 20th century physics • Utilizes a simple & elegant symmetry principle to organize what we’ve observed SU(3)C SU(2)L U(1)Y The Standard Model of particle physics is a triumph of late 20th century physics • Utilizes a simple & elegant symmetry principle to organize what we’ve observed SU(3)C SU(2)L U(1)Y Strong (QCD) Scaling violations in DIS Asymptotic freedom R(e+e-) Heavy quark systems Drell-Yan The Standard Model of particle physics is a triumph of late 20th century physics • Utilizes a simple & elegant symmetry principle to organize what we’ve observed SU(3)C SU(2)L U(1)Y Electroweak (=weak + QED) “Maximal” parity violation Conserved Vector Current CP-Violation in K, B mesons Quark flavor mixing Lepton universality….. The Standard Model of particle physics is a triumph of late 20th century physics • Most of its predictions have been confirmed e e Z0 q q Parity violation in neutral current processes: deep inelastic scattering, atomic transitions The Standard Model of particle physics is a triumph of late 20th century physics • Most of its predictions have been confirmed f f f f Jl 0 Jl g Jl Y Jl Z Neutral currents mix sin2qW The Standard Model of particle physics is a triumph of late 20th century physics • Most of its predictions have been confirmed • W, Z0 • 3rd fermion generation (CP violation, anomaly) • Higgs boson New particles should be found Not yet! We need a new Standard Model Two frontiers in the search Collider experiments (pp, e+e-, etc) at higher energies (E >> MZ) Large Hadron Collider Ultra cold neutrons CERN High energy physics Indirect searches at lower energies (E < MZ) but high precision LANSCE, SNS, NIST Particle, nuclear & atomic physics Outline I. SM Radiative Corrections & Precision Measurements II. Defects in the Standard Model III. An Example Scenario: Supersymmetry IV. Low-energy Probes of Supersymmetry • Precision measurements • “Forbidden processes” • Weak decays • lepton scattering Outline I. SM Radiative Corrections & Precision Measurements II. Defects in the Standard Model III. An Example Scenario: Supersymmetry IV. Low-energy Probes of Supersymmetry • Precision measurements • “Forbidden processes” • EDM’s • 0n decay • !e, !eg… I. Radiative Corrections & Precision Measurements in the SM The Fermi Theory of weak decays gave a successful, leading-order account n e ne n ne H EFF e F n pene GF 1 GF p n F l ne e G G l ng L eL g ln e HEFF pg (gV gA g 5 )n eL g ln e 2 2 l gV 1, gA 1.26 ng (1 g 5 ) Fermi’s theory could incorporate higher order QED contributions n n ne ne g e e QED radiative corrections: finite G m 25 2 1 3 192 2 4 1 2 F 5 The Fermi theory has trouble with higher order weak contributions n ne e ne n n ne e n ne e Weak radiative corrections: ne infinite Can’t be absorbed through suitable re-definition of GF in HEFF e All radiative corrections can be incorporated in the Standard Model with a finite number of terms n g W e e n g g n e W e Z0 ne Re-define g ne n n 0 Z e e W Finite ne GF encodes the effects of all higher order weak radiative corrections n g W e g n e 2 5 G 1 F m 3 192 Z0 n n e W e ne n e W W 2 GF g 1 r 2 2 8MW rdepends on parameters of particles inside loops ne Comparing radiative corrections in different processes can probe particle spectrum n Z e 0 g g n e n Z0 n n e Z0 e e n Z0 e n GFZ g2 2 1 rZ 2 8MW rdiffers from rZ Z0 e Comparing radiative corrections in different processes can probe particle spectrum GFZ 1 rZ r GF Z t 0 Z W 0 b W t t m rZ ~ ln M 2 t 2 W mt2 r ~ 2 MW Comparing radiative corrections in different processes can probe particle spectrum Direct Measurements Radiative corrections • 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 Stunning SM Success J. Ellison, UCI Global Analysis c2 per dof = 25.5 / 15 Agreement with SM at level of loop effects ~ 0.1% M. Grunenwald Collider Studies LEP SLD Tevatron R. Clare, UCR Collider Studies Collider Studies shad A Mt Tevatron MW Collider Studies Collider Studies Collider Studies “Blue Band” Global Fit: Winter 2004 c2 per dof = 16.3 / 13 II. Why a “New Standard Model”? • There is no unification in the early SM Universe • The Fermi constant is inexplicably large • There shouldn’t be this much visible matter • There shouldn’t be this much invisible matter The early SM Universe had no unification Couplings depend on scale Energy Scale ~ T e e() g g() The early SM Universe had no unification Early universe Present universe Standard Model 4 2 gi High energy desert Weak scale log10 ( / 0 ) Planck scale The early SM Universe had no unification Early universe Present universe Standard Model 4 for A “near miss” 2 grand unification g Gravity i High energy desert Weak scale log10 ( / 0 ) Planck scale The Fermi constant is too large Early universe Present universe Standard Model 4 GF would 2 gi shrink Unification Neutrino mass Dark Matter High energy desert Weak scale log10 ( / 0 ) Planck scale The Fermi constant is too large 2 GF g 2 2 8MW g M 4 2 W 2 2 WEAK WEAK ~ 250 GeV GF ~ 10-5/MP2 NEW H0 H0 l 2 WEAK ~ lM 2 A smaller GF would mean disaster The Sun would burn less brightly p p d e ne G ~ GF2 Elemental abundances would change p e n ne mn m p n exp p kT Tfreeze out ~ GF-2/3 2n p Y( He) 1 n p 4 Smaller GF More 4He, C, O… There is too much matter - visible & invisible - in the SM Universe Visible Matter from Big Bang Nucleosynthesis 10 nB nB ~10 ng 18 nB nB ~10 ng Measured abundances SM baryogenesis Insufficient CP violation in SM There is too much matter - visible & invisible - in the SM Universe Invisible Matter M M c No SM candidate Dark Visible Insufficient SM CP violation S. Perlmutter There must have been additional symmetries in the earlier Universe to • Unify all forces • Protect GF from shrinking • Produce all the matter that exists • Account for neutrino properties • Give self-consistent quantum gravity III. Supersymmetry • Unify all forces 3 of 4 • Protect GF from shrinking Yes • Produce all the matter that exists Maybe so • Account for neutrino properties Maybe • Give self-consistent quantum gravity Probably necessary SUSY may be one of the symmetries of the early Universe Supersymmetry Fermions Bosons e L,R , q L,R e˜ L,R , q˜ L,R gauginos ˜ , Z˜ ,g ˜, g ˜ W W , Z ,g , g Higgsinos ˜ ,H ˜ H u d sfermions Hu , H d H 0 ˜ , Z˜ ,g ˜ c ˜, H ˜ ˜ W , c u, d Charginos, neutralinos Couplings unify with SUSY Early universe Present universe Standard Model 4 2 gi Supersymmetry High energy desert Weak scale log10 ( / 0 ) Planck scale SUSY protects GF from shrinking NEW H0 ˜ NEW H0 H0 H0 2 WEAK ~ M M log terms 2 2 ˜ =0 if SUSY is exact SUSY may help explain observed abundance of matter Cold Dark Matter Candidate c0 Lightest SUSY particle Baryonic matter Unbroken phase Broken phase CP Violation t˜ H SUSY must be a broken symmetry Superpartners have not been seen M e˜ me M q˜ mq M c˜ MW ,Z ,g Theoretical models of SUSY breaking SUSY Breaking Visible World Hidden World Flavor-blind mediation Minimal Supersymmetric Standard Model (MSSM) LSM LSM + LSUSY + Lsoft ˜ M M Lsoft ˜ M gives M contains 105 new parameters How is SUSY broken? How is SUSY broken? Visible Sector: Hidden Sector: SUSY-breaking MSSM Flavor-blind mediation Gravity-Mediated (mSUGRA) W˜ , Z˜ ,g˜ , g˜ H f˜ f˜ M1 / 2 M 2 0 Hu Hd f˜ A0 b0 How is SUSY broken? Visible Sector: Hidden Sector: SUSY-breaking MSSM Flavor-blind mediation Gauge-Mediated (GMSB) f˜ ˜ , Z˜ ,g ˜ , g˜ W M1 / 2 messengers a 4 W,Z,... a M Ca 4 2 0 2 A0 0 b0 0 Mass evolution 2 ˜f dM dt 3 ˜ a C M a ˜f a t 2 ln a1 ˜ M a gaugino mass ˜f a C 0 M ˜f increases as Mq˜ increases faster than Mq˜ M˜ group structure decreases M˜ q˜ 3 ˜ (C 0,C3 0) at the weak scale Sfermion Mixing M ˜2 ˜f L 2 ˆ M 2 M LR M 2 ˜ M f˜ R 2 LR m f ( t an A f ) M m f ( cot A f ) 2 LR f˜L , ˜f R f˜1 , ˜f2 Qf < 0 Qf > 0 MSSM and R Parity PR 1 3(BL) 1 2S Matter Parity: An exact symmetry of the SM SM Particles: Superpartners: PR 1 PR 1 MSSM and R Parity MSSM conserves PR Consequences vertices have even number of superpartners 0 ˜ c Lightest SUSY particle viable dark matter candidate is stable Proton is stable Superpartners appear only in loops