Electroweak interactions and high-energy limit

A pedagogical introduction to the equivalence theorem for longitudinal vector bosons in electroweak theories is presented and the problem of high-energy behaviour of scattering amplitudes in the Standard Model is briefly reviewed. To make the treatment self-contained, the basics of the Standard Model are summarized in an appendix.Comment: Revised versio

Behavioral Response of Barren Ground Caribou to a Moving Vehicle

Behavioral responses of individual Barren Ground caribou (Rangifer tarandus granti) to a 3/4-ton pickup truck were quantified on 36 occasions. During 34 of those observations the vehicle initially approached at a speed of over 56 km/hr. Forty-eight percent of the individual caribou reacted to the vehicle by running away while 38% trotted away. The mean flight duration of females was 73 ± 11 sec, that of males 38 ± 6 sec (p=0.09). Caribou encountering a moving vehicle exhibited signs of excitement and fright, including the excitation jump and tail-up response. Reversal of direction and/or splitting of the group involved 29% of the individual caribou. The type of habitat (forested vs. open) did not have an effect on observation duration (p>0.50) or on the mean distance at which caribou were first encountered (p>0.50). The distance from the vehicle at which animals began to flee did not differ between sexes (p>0.50) or habitats (p>0.50) but was as great for both sexes as that reported for females with young calves. In forested habitat male caribou allowed a much closer approach than females (p=0.08) but closeness of approach did not differ between the sexes in open habitat (p>0.50)