Jet production in (un)polarizedppcollisions: Dependence on jet algorithm

Abstract

We investigate single-inclusive high-pT jet production in longitudinally polarized pp collisions at RHIC, with particular focus on the algorithm adopted to define the jets. Following and extending earlier work in the literature, we treat the jets in the approximation that they are rather narrow, in which case analytical results for the corresponding next-to-leading order partonic cross sections can be obtained. This approximation is demonstrated to be very accurate for practically all relevant situations, even at Tevatron and LHC energies. We confront results for cross sections and spinasymmetries based on using cone-and kt-type jet algorithms. We find that jet cross sections at RHIC can differ significantly depending on the algorithm chosen, but that the spin asymmetries are rather robust. Our results are also useful for matching threshold-resummed calculations of jet cross sections to fixed-order ones.

Threshold and Jet Radius Joint Resummation for Single-Inclusive Jet Production

“…At threshold, the invariant mass ffiffiffiffi ffi s 4 p of the unobserved partonic system recoiling against the signal jet vanishes. Note that the signal jet retains a finite invariant mass at threshold, allowing for radiation inside the jet cone [14,15]. The cancelation of infrared divergences leaves behind logarithms of the form α n s ½ln k ðzÞ=z þ , with k ≤ 2n − 1, and z ¼ s 4 =s, where s is the partonic center-ofmass (c.m.)…”

Soft Gluon Resummations in Dijet Azimuthal Angular Correlations at the Collider

“…This conclusion is independent of the jet algorithm [18]. It is interesting to note that the similar cone size dependence in Eq.…”

Single Inclusive Jet Production in Pp Collision: Dependence on Jet Algorithm

“…We have recently extended the above analytic technique to the more widely used successive combination schemes (for example, k t or anti-k t ), assuming again that the jet parameter R used to define the distance between two objects in this algorithm is not too large [7]. When systematically expanded around R = 0, the dependence of the partonic cross sections on R is of the form A log R + B + O(R 2 ).…”

“…We have also given numerical estimates of the cross section both for unpolarized and longitudinally polarized collisions at RHIC, and examined the effect of the choice of jet algorithm on the double longitudinal spin asymmetry. Here we give a brief report of [7].…”

“…We refer to this approximation as "Narrow Jet Approximation" (NJA). The NJA gives a very accurate description of the single inclusive jet cross sections at RHIC, Tevatron and even at the LHC [7]. It turned out that the cross sections for single inclusive jet production in the cone and the successive recombination algorithms differ by calculable finite terms.…”