Some Simple Criteria for Gauged R-parity

We catalog some simple conditions which are sufficient to guarantee that R-parity survives as an unbroken gauged discrete subgroup of the continuous gauge symmetry in certain supersymmetric extensions of the standard model.Comment: 11 pages, UFIFT-HEP-92-22. v2: TeX formatting fixed, no other change

Predictive fermion mass matrix ansatzes in non-supersymmetric SO(10) grand unification

We investigate the status of predictive fermion mass ansatzes which make use of the grand unification scale conditions $m_e=m_d/3$, $m_\mu =3m_s$, and $\mid V_{cb}\mid =\sqrt{m_{c}/m_{t}}$ in non-supersymmetric SO(10) grand unification. The gauge symmetry below an intermediate symmetry breaking scale $M_I$ is assumed to be that of the standard model with either one Higgs doublet or two Higgs doublets . We find in both cases that a maximum of 5 standard model parameters may be predicted within $1\sigma$ experimental ranges. We find that the standard model scenario predicts the low energy $\mid V_{cb}\mid$ to be in a range which includes its experimental mid-value 0.044 and which for a large top mass can extend to lower values than the range resulting in the supersymmetric case. In the two Higgs standard model case, we identify the regions of parameter space for which unification of the bottom quark and tau lepton Yukawa couplings is possible at grand unification scale. In fact, we find that unification of the top, bottom and tau Yukawa couplings is possible with the running b-quark mass within the $1\sigma$ preferred range $m_b=4.25\pm 0.1\, GeV$ provided $\alpha_{3c}(M_Z)$ is near the low end of its allowed range. In this case, one may make 6 predictions which include $\mid V_{cb}\mid$ within its $90\%$ confidence limits. However unless the running mass $m_b>4.4\, GeV$, third generation Yukawa coupling unification requires the top mass to be greater thanComment: 30 pages, 8 figures available on request from [email protected], Late

Do About Half the Top Quarks at FNAL Come From Gluino Decays?

We argue that it is possible to make a consistent picture of FNAL data including the production and decay of gluinos and squarks. The additional cross section is several pb, about the size of that for Standard Model (SM) top quark pair production. If the stop squark mass is small enough, about half of the top quarks decay to stop squarks, and the loss of SM top quark pair production rate is compensated by the supersymmetric processes. This behavior is consistent with the reported top quark decay rates in various modes and other aspects of the data, and suggests several other possible decay signatures. This picture can be tested easily with more data, perhaps even with the data in hand, and demonstrates the potential power of a hadron collider to determine supersymmetric parameters. It also has implications for the top mass measurement and the interpretation of the LEP $R_b$ excess.Comment: 18 pages, including 4 Postscript figures, uses epsf.tex, also available at http://www.hep.anl.gov/theory/mrenna

V,W and X in Technicolour Models

Light techni-fermions and pseudo Goldstone bosons that contribute to the electroweak radiative correction parameters V,W and X may relax the constraints on technicolour models from the experimental values of the parameters S and T. Order of magnitude estimates of the contributions to V,W and X from light techni-leptons are made when the the techni-neutrino has a small Dirac mass or a large Majorana mass. The contributions to V,W and X from pseudo Goldstone bosons are calculated in a gauged chiral Lagrangian. Estimates of V,W and X in one family technicolour models suggest that the upper bounds on S and T should be relaxed by between 0.1 and 1 depending upon the precise particle spectrum.Comment: 19 pages + 2 pages of ps figs, SWAT/1

Flavour Universal Dynamical Electroweak Symmetry Breaking

The top condensate see-saw mechanism of Dobrescu and Hill allows electroweak symmetry to be broken while deferring the problem of flavour to an electroweak singlet, massive sector. We provide an extended version of the singlet sector that naturally accommodates realistic masses for all the standard model fermions, which play an equal role in breaking electroweak symmetry. The models result in a relatively light composite Higgs sector with masses typically in the range of (400-700)~GeV. In more complete models the dynamics will presumably be driven by a broken gauged family or flavour symmetry group. As an example of the higher scale dynamics a fully dynamical model of the quark sector with a GIM mechanism is presented, based on an earlier top condensation model of King using broken family gauge symmetry interactions (that model was itself based on a technicolour model of Georgi). The crucial extra ingredient is a reinterpretation of the condensates that form when several gauge groups become strong close to the same scale. A related technicolour model of Randall which naturally includes the leptons too may also be adapted to this scenario. We discuss the low energy constraints on the massive gauge bosons and scalars of these models as well as their phenomenology at the TeV scale.Comment: 22 pages, 3 fig

Search for light-to-heavy quark flavor changing neutral currents in νμN\nu _{\mu}N and νˉμN\bar{\nu}_{\mu}N scattering at the Tevatron

We report on a search for flavor-changing neutral-currents (FCNC) in the production of heavy quarks in deep inelastic $\nu_{\mu}N$ and $\bar{\nu}_{\mu}N$ scattering by the NuTeV experiment at the Fermilab Tevatron. This measurement, made possible by the high-purity NuTeV sign-selected beams, probes for FCNC in heavy flavors at the quark level and is uniquely sensitive to neutrino couplings of potential FCNC mediators. All searches are consistent with zero, and limits on the effective mixing strengths $$, $| V_{db}| ^{2}$, and $| V_{sb}| ^{2}$ are obtained

Potentially resistant microorganisms in intubated patients with hospital-acquired pneumonia: the interaction of ecology, shock and risk factors

Purpose: As per 2005 American Thoracic Society and Infectious Disease Society of America (ATS/IDSA) guidelines for managing hospital-acquired pneumonia, patients with early-onset pneumonia and without risk factors do not need to be treated for potentially resistant microorganisms (PRM). Methods: This was a secondary analysis of a prospective, observational, cohort, multicentre study conducted in 27 ICUs from nine European countries. Results: From a total of 689 patients with nosocomial pneumonia who required mechanical ventilation, 485 patients with confirmed etiology and antibiotic susceptibility were further analysed. Of these patients, 152 (31.3 %) were allocated to group 1 with early-onset pneumonia and no risk factors for PRM acquisition, and 333 (68.7 %) were classified into group 2 with early-onset pneumonia with risk factors for PRM or late-onset pneumonia. Group 2 patients were older and had more chronic renal failure and more severe illness (SAPS II score, 44.6 ± 16.5 vs. 47.4 ± 17.8, p = 0.04) than group 1 patients. Trauma patients were more frequent and surgical patients less frequent in group 1 than in group 2 (p < 0.01). In group 1, 77 patients (50.7 %) had PRM in spite of the absence of classic risk factors recognised by the current guidelines. A logistic regression analysis identified that presence of severe sepsis/septic shock (OR = 3.7, 95 % CI 1.5-8.9) and pneumonia developed in centres with greater than 25 % prevalence of PRM (OR = 11.3, 95 % CI 2.1-59.3) were independently associated with PRM in group 1 patients. Conclusions: In patients admitted to ICUs with a prevalence of PRM greater than 25 % or with severe sepsis/septic shock, empiric therapy for group 1 nosocomial pneumonia requiring mechanical ventilation should also include agents likely to be effective for PRM pathogens

Structural requirements for the cytoprotective actions of mono-unsaturated fatty acids in the pancreatic β-cell line, BRIN-BD11

Background and purpose: Exposure of pancreatic β-cells to long-chain free fatty acids leads to differential responses according to the chain length and degree of unsaturation. In particular, long-chain saturated molecules such as palmitate (C16:0) cause apoptosis, whereas equivalent mono-unsaturated species (for example, palmitoleate (C16:1)) are not overtly toxic. Moreover, mono-unsaturates exert a powerful cytoprotective response against a range of proapoptotic stimuli. However, the structural requirements that determine cytoprotection have not been determined and form the basis of the present study