Effective description of brane terms in extra dimensions

We study how theories defined in (extra-dimensional) spaces with localized defects can be described perturbatively by effective field theories in which the width of the defects vanishes. These effective theories must incorporate a ``classical'' renormalization, and we propose a renormalization prescription a la dimensional regularization for codimension 1, which can be easily used in phenomenological applications. As a check of the validity of this setting, we compare some general predictions of the renormalized effective theory with those obtained in a particular ultraviolet completion based on deconstruction.Comment: 28 page

Z' Decays into Four Fermions

If a new $Z'$ is discovered with a mass $\sim 1 \ TeV$ at LHC/SSC, its (rare) decays into two charged leptons plus missing transverse energy will probe the $Z'$ coupling to the lepton doublet $(\nu,e)_L$ and to $W^+W^-$, allowing further discrimination among extended electroweak models.Comment: 9 pages plus 1 figure (not included but available), UG-FT-22/9

Identifying Unconventional E6_{\bf 6} Models at e+e−e^+ e^- Colliders

Recently it was shown that, in the framework of superstring inspired \E models, the presence of generation dependent discrete symmetries allows us to construct a phenomenologically viable class of models in which the three generations of fermions do not have the same embedding within the fundamental {\bf 27} dimensional representation of E$_6$. In this scenario, these different embeddings of the conventional fermions imply that the left-handed charged leptons and the right-handed $d$-type quarks are coupled in a non--universal way to the new neutral gauge bosons $(Z_\theta)$ present in these models. It was also shown that a unique signature for this scenario, would be a deviation from unity for the ratio of cross sections for the production of two different lepton species in $e^+e^-$ annihilation. However, several different scenarios are possible, depending on the particular assignment chosen for $e_L$, $\mu_L$ and $\tau_L$ and for the right-handed $d$-type quarks, as well as on the type of $Z_\theta$ boson. Such scenarios can not be disentangled from one another by means of cross section measurements alone. In this paper we examine the possibility of identifying the pattern of embeddings through measurements of polarized and unpolarized asymmetries for fermion pair-production at the 500 GeV $e^+e^-$ Next Linear Collider (NLC). We show that it will be possible to identify the different patterns of unconventional assignments for the left-handed leptons and for the $b_R$ quark, for $Z_\theta$ masses as large as $\sim 1.5$ TeV.Comment: Plain Tex, 15 pages, + 9 figure available upon request ([email protected] or [email protected]), UM-TH 93--1

Impact of right-handed interactions on the propagation of Dirac and Majorana neutrinos in matter

Dirac and Majorana neutrinos can be distinguished in relativistic neutrino oscillations if new right-handed interactions exist, due to their different propagation in matter. We review how these new interactions affect neutrino oscillation experiments and discuss the size of this eventually observable effect for different oscillation channels, baselines and neutrino energies.Comment: 26 pages, 5 figure

Understanding Radiatively Induced Lorentz-CPT Violation in Differential Regularization

We have investigated the perturbative ambiguity of the radiatively induced Chern-Simons term in differential regularization. The result obtained in this method contains all those obtained in other regularization schemes and the ambiguity is explicitly characterized by an indefinite ratio of two renormalization scales. It is argued that the ambiguity can only be eliminated by either imposing a physical requirement or resorting to a more fundamental principle. Some calculation techniques in coordinate space are developed in the appendices.Comment: RevTex, 14 pages, one figure drawn by FEYNMAN, several references are modified and a paragraph about a general choice on the mass scales is added in page

Leptophobic U(1)'s and the R_b - R_c Crisis

In this paper, we investigate the possibility of explaining both the R_b excess and the R_c deficit reported by the LEP experiments through Z-Z' mixing effects. We have constructed a set of models consistent with a restrictive set of principles: unification of the Standard Model (SM) gauge couplings, vector- like additional matter, and couplings which are both generation-independent and leptophobic. These models are anomaly-free, perturbative up to the GUT scale, and contain realistic mass spectra. Out of this class of models, we find three explicit realizations which fit the LEP data to a far better extent than the unmodified SM or MSSM and satisfy all other phenomenological constraints which we have investigated. One realization, the \eta-model coming from E_6, is particularly attractive, arising naturally from geometrical compactifications of heterotic string theory. This conclusion depends crucially on the inclusion of a U(1) kinetic mixing term, whose value is correctly predicted by renormalization group running in the E_6 model given one discrete choice of spectra.Comment: LaTeX, 26 pages, 5 embedded EPSF figures. Version to be published in Phys. Rev.

Evaluación de soya geneticamente modificada por Q-PCR en el procesamiento de leche de soya.

Cuantificar el porcentual de soya RR en la producción del extracto hidrosoluble de soya, en las formulaciones de 0,1 hasta 50 % de soya RR® por PCR en tiempo real usando una sonda del tipo Taqman 35S GMO

Testing the handedness of a heavy W′W^{\prime} at future hadron colliders

We show that the associated production $pp\to W^{\prime}W$, and the rare decay $pp\to W'\to \bar\ell\ell W$ are useful tests of $W'$ couplings to fermions at future hadron colliders. For $M_{W'}\sim (1 - 3)$ TeV they would allow a clean determination on whether the $W'$ couples to $V-A$ or $V+A$ currents. As an illustration a model in which the $W^{\prime\pm}$ couples only to $V-A$ currents is contrasted to the left-right symmetric models which involve $V+A$ currents.Comment: UPR-0579T 16 pages, 3 figures (not included

The lepton flavor violating decays Z→liljZ\to l_i l_j in the simplest little Higgs model

In the simplest little Higgs model the new flavor-changing interactions between heavy neutrinos and the Standard Model leptons can generate contributions to some lepton flavor violating decays of $Z$-boson at one-loop level, such as $Z \to \tau^{\pm}\mu^{\mp}$, $Z\to \tau^{\pm}e^{\mp}$, and $Z \to \mu^{\pm}e^{\mp}$. We examine the decay modes, and find that the branching ratios can reach $10^{-7}$ for the three decays, which should be accessible at the Giga$Z$ option of the ILC.Comment: 12 pages, 9 figure