Reconstruction of the Extended Gauge Structure from Z′Z' Observables at Future Colliders

The discovery of a new neutral gauge boson $Z'$ with a mass in the TeV region would allow for determination of gauge couplings of the $Z'$ to ordinary quarks and leptons in a model independent way. We show that these couplings in turn would allow us to determine the nature of the extended gauge structure. As a prime example we study the $E_6$ group. In this case two discrete constraints on experimentally determined couplings have to be satisfied. If so, the couplings would then uniquely determine the two parameters, $\tan \beta$ and $\delta$, which fully specify the nature of the $Z'$ within $E_6$. If the $Z'$ is part of the $E_6$ gauge structure, then for $M_{Z'}=1$ TeV $\tan \beta$ and $\delta$ could be determined to around $10\%$ at the future colliders. The NLC provides a unique determination of the two constraints as well as of $\tan \beta$ and $\delta$, though with slightly larger error bars than at the LHC. On the other hand, since the LHC primarily determines three out of four normalized couplings, it provides weaker constraints for the underlying gauge structure.Comment: 14 pages LaTeX using RevTeX and psfig.sty. TeX source and 3 PS figures, tarred, compressed and uuencoded; also available via anonymous ftp to ftp://dept.physics.upenn.edu/pub/Cvetic/UPR-636-T

Unique Identification of Lee-Wick Gauge Bosons at Linear Colliders

Grinstein, O'Connell and Wise have recently presented an extension of the Standard Model (SM), based on the ideas of Lee and Wick (LW), which demonstrates an interesting way to remove the quadratically divergent contributions to the Higgs mass induced by radiative corrections. This model predicts the existence of negative-norm copies of the usual SM fields at the TeV scale with ghost-like propagators and negative decay widths, but with otherwise SM-like couplings. In earlier work, it was demonstrated that the LW states in the gauge boson sector of these models, though easy to observe, cannot be uniquely identified as such at the LHC. In this paper, we address the issue of whether or not this problem can be resolved at an $e^+e^-$ collider with a suitable center of mass energy range. We find that measurements of the cross section and the left-right polarization asymmetry associated with Bhabha scattering can lead to a unique identification of the neutral electroweak gauge bosons of the Lee-Wick type.Comment: 16 pages, 6 figures; discussion and references adde

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

The effects of non-universal extra dimensions on the radiative lepton flavor decays \mu\to e\gamma and \tau\to \mu\gamma in the two Higgs doublet model

We study the effect of non-universal extra dimensions on the branching ratios of the lepton flavor violating processes \mu\to e\gamma and \tau\to \mu\gamma in the general two Higgs doublet model. We observe that these effects are small for a single extra dimension, however, in the case of two extra dimensions there is a considerable enhancement in the additional contributions.Comment: 16 Pages, 9 Figure

The Production of Z′Z' Associated With Photons or Jets as a Probe of New Gauge Boson Couplings

We examine the production of a new $Z'$ gauge boson in association with photons or jets at future hadron supercolliders as a probe of its couplings to fermions. Associated jet production is found to be rather insensitive to these couplings and suffers from large uncertainties as well as substantial backgrounds. On the other hand, the ratio of rates for associated photon $Z'$ production to that of conventional $Z'$ production has a rather clean signature (once appropriate cuts are made), and is found to be quite sensitive to the choice of extended electroweak model, while being simultaneously insensitive to structure function uncertainties and QCD corrections. Rates at both the SSC and LHC are significant for $Z'$ masses in the 1 TeV range.Comment: 14pp, 6 figs(not included), LaTex, ANL-HEP-PR-92-5

Fulminant myocarditis parvovirus B19 related in a young woman

We present the case of a 18-year-old female with fulminant lymphocytic myocarditis caused by Parvovirus B19 (PVB19), successfully treated using temporary LVAD. In the literature there is no consensus on the surgical strategy. While some surgeons prefer to use a single device supporting only the LV, others prefer to start immediately with a biventricular supporting. At pre-procedural ultrasound evaluation, her anatomical features were not suitable for a percutaneous device such as the Impella. Thus, a temporary paracorporeal continuous flow LVAD was inserted. The heart recovery allowed LVAD removal 9 days after the implant

Generating socially appropriate tutorial dialog

Analysis of student-tutor coaching dialogs suggest that good human tutors attend to and attempt to influence the motivational state of learners. Moreover, they are sensitive to the social face of the learner, and seek to mitigate the potential face threat of their comments. This paper describes a dialog generator for pedagogical agents that takes motivation and face threat factors into account. This enables the agent to interact with learners in a socially appropriate fashion, and foster intrinsic motivation on the part of the learner, which in turn may lead to more positive learner affective states

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

Testing the Nature of Kaluza-Klein Excitations at Future Lepton Colliders

With one extra dimension, current high precision electroweak data constrain the masses of the first Kaluza-Klein excitations of the Standard Model gauge fields to lie above $\simeq 4$ TeV. States with masses not much larger than this should be observable at the LHC. However, even for first excitation masses close to this lower bound, the second set of excitations will be too heavy to be produced thus eliminating the possibility of realizing the cleanest signature for KK scenarios. Previous studies of heavy $Z'$ and $W'$ production in this mass range at the LHC have demonstrated that very little information can be obtained about their couplings to the conventional fermions given the limited available statistics and imply that the LHC cannot distinguish an ordinary $Z'$ from the degenerate pair of the first KK excitations of the $\gamma$ and $Z$. In this paper we discuss the capability of lepton colliders with center of mass energies significantly below the excitation mass to resolve this ambiguity. In addition, we examine how direct measurements obtained on and near the top of the first excitation peak at lepton colliders can confirm these results. For more than one extra dimension we demonstrate that it is likely that the first KK excitation is too massive to be produced at the LHC.Comment: 38 pages, 10 Figs, LaTex, comments adde

CP Violation and Family Mixing in the Effective Electroweak Lagrangian

We construct the most general effective Lagrangian of the matter sector of the Standard Model, including mixing and CP violating terms. The Lagrangian contains the effective operators that give the leading contribution in theories where the physics beyond the Standard Model shows at a scale $\Lambda >>M_{W}$. We perform the diagonalization and passage to the physical basis in full generality. We determine the contribution to the different observables and discuss the possible new sources of CP violation, the idea being to be able to gain some knowledge about new physics beyond the Standard Model from general considerations, without having to compute model by model. The values of the coefficients of the effective Lagrangian in some theories, including the Standard Model, are presented and we try to draw some general conclusions about the general pattern exhibited by physics beyond the Standard Model in what concerns CP violation. In the process we have had to deal with two theoretical problems which are very interesting in their own: the renormalization of the CKM matrix elements and the wave function renormalization in the on-shell scheme when mixing is present.Comment: A misplaced sentence was correcte