INFRARED RENORMALONS AND POWER SUPPRESSED EFFECTS IN E(-) JET EVENTS()E()

We study the effect of infrared renormalons upon shape variables that are commonly used to determine the strong coupling constant in e(+)e(- ) annihilation into hadronic jets. We consider the model of QCD in the limit of large n(f). We find a wide variety of different behaviours o f shape variables with respect to power suppressed effects induced by infrared renormalons. In particular, we find that oblateness is affect ed by 1/Q non-perturbative effects even away from the two-jet region, and the energy-energy correlation is affected by 1/Q non-perturbative effects for all values of the angle. On the contrary, variables like t hrust, the c parameter, the heavy jet mass, and others, do not develop any 1/Q correction away from the two-jet region at the leading n(f) l evel. We argue that 1/Q corrections will eventually arise at subleadin g n(f) level, but that they could maintain an extra alpha(s)(Q) suppre ssion. We conjecture therefore that the leading power correction to sh ape variables will have in general the form alpha(s)(n)(Q)/Q, and it m ay therefore be possible to classify shape variables according to the value of n.