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

Impact of extra particles on indirect Z' limits

We study the possibility of relaxing the indirect limits on extra neutral vector bosons by their interplay with additional new particles. They can be systematically weakened, even below present direct bounds at colliders, by the addition of more vector bosons and/or scalars designed for this purpose. Otherwise, they appear to be robust.Comment: Latex 23 pages, 8 eps figures. Minor changes, version published in Phys. Rev.

Light neutrino propagation in matter without heavy neutrino decoupling

We review the propagation of light neutrinos in matter assuming that their mixing with heavy neutrinos is close to present experimental limits. The phenomenological implications of the non-unitarity of the light neutrino mixing matrix for neutrino oscillations are discussed. In particular we show that the resonance effect in neutrino propagation in matter persists, but for slightly modified values of the parameters and with the maximum reduced by a small amount proportional to the mixing between light and heavy neutrinos squared.Comment: 11 pages, 1 figure, contribution to Stefan Pokorski 60th birthda

Differential Renormalization of Gauge Theories

The scope of constrained differential renormalization is to provide renormalized expressions for Feynman graphs, preserving at the same time the Ward identities of the theory. It has been shown recently that this can be done consistently at least to one loop for abelian and non-abelian gauge theories. We briefly review these results, evaluate as an example the gluon selfenergy in both coordinate and momentum space, and comment on anomalies.Comment: LaTex, 8 pages with 1 ps figures, talk given at the Zeuthen Workshop on Elementary Particle Physics "Loops and Legs in Gauge Theories", Rheinsberg, Germany, April 19-24, 1998, to appear in Acta Physica Polonica

Statins and non-alcoholic fatty liver disease

Dear Editor, In April 9 issue, van den Berg et al1 report interesting results on the indication for lipid‐lowering treatment in a large cohort with suspected non‐alcoholic fatty liver disease (NAFLD) within the population‐based Lifelines Cohort Study. Fatty liver index (FLI) ≥60 was used as a proxy of NAFLD and the NAFLD fibrosis score (NFS) to identify the NAFLD patients with suspected advanced fibrosis. Cardiovascular disease (CVD) risk was established by the 2016 European society of Cardiology/European Atherosclerosis Society (ESC/EAS) Guidelines for the Management of Dyslipidemias.2 Subjects with FLI ≥ 60 (suspected NAFLD) had an increased 10‐ year predicted cardiovascular risk compared to those with FLI < 60 with an approximately 2 times higher need for statin therapy based on CVD risk prediction and their LDL cholesterol level. Subjects with a FLI ≥ 60 were more likely to be classified with type 2 diabetes, Metabolic Syndrome (MetS), history of CVD and impaired renal function. Interestingly, estimated 10‐year very high cardiovascular risk was approximately 4 times higher in subjects with a NFS > 0.676 compared to those with the absence of advanced fibrosis. Finally, indication for statin treatment was positively associated with a FLI ≥ 60 after controlling for age, sex, current smoking, impaired renal function, and the presence of MetS and its individual components. The above results have an even greater relevance if we consider that all the subjects who were already on statin therapy were subtracted from the analysis. These findings may have an important clinical relevance and emphasize the need for effective treatment with statins in patients with NAFLD. Indeed, accumulating evidence suggests that CVD, rather than liver disease, dictates the outcomes in NAFLD.3 Besides, in most subjects NAFLD constitutes the hepatic component of MetS and numerous patients have atherogenic dyslipidemia. This study further supports the results of a previous study by our group where under prescription of statins in patients with NAFLD was observed.4 In fact, mild liver enzyme elevation remains a concern and despite its proven efficacy and safety,5 statin administration is sometimes limited by the worry about related side effects. Indeed, there is a tendency of general physicians to discourage statin use in patients with baseline elevation of serum liver enzymes and/ or to discontinue medication when minor alterations were appreciated. Of note, in our study, statin under‐use was high also in patients at very high CV risk such as those with a previous CV event. This study by van den Berg et al further stresses the issue of under prescription of statins in people with NAFLD and indication for treatment, based on CV risk class and low‐density lipoprotein cholesterol target according to ESC/EAS guidelines

The Minimal Extension of the SM and the Neutrino Oscillation Data

We study the simplest Standard Model estension with only one extra right-handed neutrino. In this case there are two massless $m_{1,2}$ and two massive $m_{3,4}$ neutrinos, and in principle both solar and atmospheric anomalies can be described in two different scenarios, $m_3 << m_4$ (scheme I) and $m_3 \simeq m_4$ (scheme II). However, neither bi-maximal mixing nor the dark matter problem are explained in this minimal extension. Only scheme II can accommodate simultaneously maximal mixing for atmospheric neutrinos and the small mixing angle MSW solution for the solar anomaly. This scenario can be tested in the BOREXINO experiment.Comment: 9 pages, Presented by J. Gluza at the XXIII School of Theoretical Physics, Ustron'99, Poland, September 15-22, 199

Neutrino oscillations beyond the Standard Model

We address the possible impact of New Physics on neutrino oscillation experiments. This can modify the neutrino production, propagation and/or detection, making the full cross section non-factorizable in general. Thus, for example, the neutrino flux may not be properly described assuming an unitary MNS matrix and/or neutrinos may propagate differently depending of their Dirac or Majorana character. Interestingly enough, present limits on New Physics still allow for observable effects at future neutrino experiments.Comment: 2 pages, 2 figures, Presented at the Neutrino 08 Conference, Christchurch, New Zealand, May 25-31, 200