Thresholds in s evolution and the pT dependence of jetsV

We point out that high-mass thresholds in the evolution of the strong-interaction coupling parameter s , due to gluinos, squarks and possible new heavy quarks, could introduce appreciable corrections to the transverse momentum dependence of jet production at the Tevatron. If the new thresholds were near scale = 200 GeV, then within the limits of asymptotic freedom they could introduce up to 11% increase in s () (and hence 23% increase in jet production) at scale = 500 GeV, compared to Standard Model extrapolations. The CDF experiment at the Fermilab Tevatron collider has recently reported that inclusive jet production in p p collisions appears to exceed next-to-leading order QCD expectations in the transverse momentum range 200 < p T (j) < 420 GeV 1]. It has been suggested that the discrepancy might be explained by a modiied gluon distribution in the nucleon 2]. However, it is also possible that some new physics may be playing a signiicant role. In the present note we point out that high-mass thresholds due to gluinos (~ g) and squarks (~ q), plus possible new non-standard quarks (Q) and squarks (~ Q), would change the evolution of the QCD coupling parameter s () at large values of the scale Q. This eeect could give a signiicant enhancement above standard expectations, both for s () at large and hence also for the jet production cross section at large p T. The evolution equation for s () at one loop can be written d dt s ()] ?1 = b 3 2 ; (1) with b 3 = 11 ? 2 3 n f ; (2) where t = ln and n f is the number of quark avors that are active, i.e. that have > m q 3]. In a supersymmetric (SUSY) model, b 3 reduces by two units above the gluino threshold and by 1 3 above each successive squark threshold (assuming degenerate Land R-chiral squarks), giving b 3 = 9 ? 2 3 n f ? 1 3 ~ n f ; (3) where we assume the gluino is active and ~ n f denotes the number of active squark avors. It is clear that as the scale increases, successively more thresholds are crossed and the rate of evolution of s ()] ?1 decreases. Accordingly, the rate of fall of s () as increases (asymptotic freedom) is reduced with each successive threshold. Further new …