Anomalous moments of the top quark arises from one loop corrections to the vertices ttg and ttγ. We study these anomalous couplings in different frameworks: effective theories, Standard Model and 2HDM. We use available experimental results in order to get bounds on these anomalous couplings.

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Broad-band optical and infrared observations in the R, I, and J, H, Ks bands of comet McNaught-Hartley (C/1999 T1) were performed from Jan. 25 to Feb. 4, 2001, shortly after the comet perihelion on Dec. 14, 2000. For the time the comet was observed, it did not show any peculiar behaviour either in the infrared or in the optical, that is, no non

We report on the discovery of variable circular polarization from the remnant of Nova Chamaeleontis 1953 (RR Cha). The circular polarization appears to be modulated on the spin period of the primary and harmonics of the positive superhump period, with an amplitude peak-to-peak of almost ~10 per cent with both negative and positive polarization. A

We constrain the basic cosmological parameters using the first observations by the Very Small Array (VSA) in its extended configuration, together with existing cosmic microwave background data and other cosmological observations. We estimate cosmological parameters for four different models of increasing complexity. In each case, careful