LFV and LUV at CLEO Lepton-Flavor Violation: –Probe non-SM physics and/or SM extensions –Here, report on Upsilon(1S)   Complements other studies MEG (   e  Many searches for    Lepton UniVersality: –“Sometimes a lepton is just a lepton” (Freud [sic]) –If not, then something interesting!

LFV in the charged sector d t b Generation Quarks Leptons   e c u s e   Energy Quark mixing (CKM) Neutrino Oscillations Mixing in the charged Lepton sector?

Lepton Flavor Violation Sakharov Conditions for Matter- Universe: –Baryon Number Violation (B [L=lepton no.]) –C-parity (CP-parity) Violation –Universe non-thermal for some time B, L “accidental symmetries”, but B-L good QN

LFV summary:  decay  → e   → eA  → eee SUSY SU(5) BR(   e  ) =   A  eA =  BR(     ) = SUSY SU(5) BR(   e  ) =   A  eA =  BR(     ) = Current Limits: BR(  +  e +  ) < 1.2 x (MEGA) 1)  Ti → eTi < 7 x (SINDRUM II) 2) Current Limits: BR(  +  e +  ) < 1.2 x (MEGA) 1)  Ti → eTi < 7 x (SINDRUM II) 2) 1) hep-ex/ ) A. van der Schaaf, priv. comm. BR Year “Supersymmetric parameterspace accessible by LHC” (Ritt, MEGs)

Upsilon Decays access a different kinematic regime!

Or add interactions at new scale Datta et al (PRD60, , 1999: Y   l<0.01; J/p   l<6x10 -7

CLEO search The detector: CLEO was the first “CLEO-type” detector 10 GeV energy regime; Good resolution!

Experimental Search Search for Y   ;   e Off-resonance samples used for control & comparison. Primary search variables are scaled momenta of two charged tracks. Extended maximum likelihood used to evaluate event-by-event consistency with LFV

Signal parametrized as f(scaled electron,scaled muon momentum)

Known backgrounds saturate observables

No signal observed over background  set limits

Lepton Universality Here, “LUV”   (nS)  l + l - universal (if no BSM). LUV NOT statement that  (nS)  l + l - =  (mS)  l + l -. In case of Upsilon: –Y   easiest 2 Back-to-Back tracks Direct Continuum Subtraction –Y  ee coupling extracted through total Upsilon width Bhabha subtraction otherwise BIG –Here, discuss measurement of Y   + comparison with Y   and Y  ee –Very similar to Y   : straightforward ON-OFF –To minimize systematics, use consistent muon ID for both dilepton modes

Dielectronic widths (PRL96, , 2006) NOTE: Precision measurements – typically 2%!

Measure tau pair xsct w/ many modes: “Expected ratio”=0.82 (phase space)

Compare on-off resonance yields:

MC to derive efficiency

RESULTS (relative)

Internal consistency

Absolute BF (+ratio just presented)

Conclusions Standard Model once again triumphs. –Although differences in dileptonic widths, resonance-to- resonance, are interesting… No indication of departures from SM, but keep looking… No more Upsilon resonance data  Resonance program for J/psi underway.

LFV in the SM vs. SUSY (m  eg) SM SUSY probes slepton mixing matrix ≈ LFV in the SM is immeasurable small SUSY models predicts BR(  → e  ) just below the current experimental limit of 1.2 x Decay  → e  is free of “SM background” (no hadronic corrections) LFV in the SM is immeasurable small SUSY models predicts BR(  → e  ) just below the current experimental limit of 1.2 x Decay  → e  is free of “SM background” (no hadronic corrections) The discovery of  → e  would by physics beyond the SM