SET based experiments for HTSC materials: II

The cuprates seem to exhibit statistics, dimensionality and phase transitions in novel ways. The nature of excitations [i.e. quasiparticle or collective], spin-charge separation, stripes [static and dynamics], inhomogeneities, psuedogap, effect of impurity dopings [e.g. Zn, Ni] and any other phenomenon in these materials must be consistently understood. In this note we further discuss our original suggestion of using Single Electron Tunneling Transistor [SET] based experiments to understand the role of charge dynamics in these systems. Assuming that SET operates as an efficient charge detection system we can expect to understand the underlying physics of charge transport and charge fluctuations in these materials for a range of doping. Experiments such as these can be classed in a general sense as mesoscopic and nano characterization of cuprates and related materials. In principle such experiments can show if electron is fractionalized in cuprates as indicated by ARPES data. In contrast to flux trapping experiments SET based experiments are more direct in providing evidence about spin-charge separation. In addition a detailed picture of nano charge dynamics in cuprates may be obtained.Comment: 10 pages revtex plus four figures; ICMAT 2001 Conference Symposium P: P10-0

Search for lepton flavor violation via the intense high-energy muon beam

A deep inerastic scattering process \mutau is discussed to study lepton flavor violation between muons and tau leptons. In supersymmetric models, the Higgs boson mediated diagrams could be important for this reaction. We find that at a muon energy ($E_{\mu}$) higher than 50 GeV, the predicted cross section significantly increases due to the contribution from sea $b$-quarks. The number of produced tau leptons can be $\mathcal{O}(10^4)$ at $E_{\mu}$= 300 GeV from $10^{20}$ muons, whereas $\mathcal{O}(10^2)$ events are given at $E_{\mu}= 50$ GeV.Comment: Contribution to the 6th International Workshop on Neutrino Factories & Superbeams(NuFact04), Jul. 26-Aug. 1, 2004, Osaka Univerisity, Osaka, Japan, talk given by S.K., to appear in the Proceedings, 3 pages, 4 figure

The Anomalous Magnetic Moment of the Muon and Higgs-Mediated Flavor Changing Neutral Currents

In the two-Higgs doublet extension of the standard model, flavor-changing neutral couplings arise naturally. In the lepton sector, the largest such coupling is expected to be $\mu-\tau-\phi#. We consider the effects of this coupling on the anomalous magnetic moment of the muon. The resulting bound on the coupling, unlike previous bounds, is independent of the value of other unknown couplings. It will be significantly improved by the upcoming E821 experiment at Brookhaven National Lab.Comment: 7 pages Latex, 2 figure

Multi-scale Renormalisation Group Improvement of the Effective Potential

Using the renormalisation group and a conjecture concerning the perturbation series for the effective potential, the leading logarithms in the effective potential are exactly summed for $O(N)$ scalar and Yukawa theories.Comment: 19 pages, DIAS STP 94-09. Expanded to check large N limit, typo's corrected, to appear in Phys Rev

Leptonic Charged Higgs Decays in the Zee Model

We consider the version of the Zee model where both Higgs doublets couple to leptons. Within this framework we study charged Higgs decays. We focus on a model with minimal number of parameters consistent with experimental neutrino data. Using constraints from neutrino physics we (i) discuss the reconstruction of the parameter space of the model using the leptonic decay patterns of both of the two charged Higgses, $h_{1,2}^{+}\to \ell_{j}^{+}\nu_{i}$, and the decay of the heavier charged Higgs, $h_{2}^{+}\to h^{+}_{1}h^{0}$; (ii) show that the decay rate $\Gamma(h_{1}^{+}\to \mu^{+}\nu_{i})$ in general is enhanced in comparision to the standard two Higgs doublet model while in some regions of parameter space $\Gamma(h_{1}^{+}\to \mu^{+}\nu_{i})$ even dominates over $\Gamma(h_{1}^{+}\to \tau^{+}\nu_{i})$.Comment: 25 pages, 9 figure

Production, Collection and Utilization of Very Long-Lived Heavy Charged Leptons

If a fourth generation of leptons exists, both the neutrino and its charged partner must be heavier than 45 GeV. We suppose that the neutrino is the heavier of the two, and that a global or discrete symmetry prohibits intergenerational mixing. In that case, non-renormalizable Planck scale interactions will induce a very small mixing; dimension five interactions will lead to a lifetime for the heavy charged lepton of $O(1-100)$ years. Production of such particles is discussed, and it is shown that a few thousands can be produced and collected at a linear collider. The possible uses of these heavy leptons is also briefly discussed.Comment: 9 pages Late