arXiv subjects

D. A. Kosower

Publications and source records attributed to D. A. Kosower.

63 records · Page 4Linked to original sources

arXiv1994

Recent Progress in One-Loop Multi-Parton Calculations

We describe techniques that simplify the calculation of one-loop QCD amplitudes with many external legs, which are needed for next-to-leading-order (NLO) corrections to multi-jet processes. The constraints imposed by perturbative unitarity, collinear singularities and a supersymmetry-inspired organization of helicity amplitudes are particularly useful. Certain sequences of one-loop helicity amplitudes may be obtained for an arbitrary number of external gluons using these techniques. We also report on progress in completing the set of one-loop helicity amplitudes required for NLO three-jet production at hadron colliders, namely the amplitudes with two external quarks and three gluons. (Contribution presented by L. Dixon at the workshop ``QCD'94'', Montpellier, France, July 7-13, 1994. To appear in those proceedings.)

hep-ph↗

arXiv1994

One-Loop Gauge Theory Amplitudes with an Arbitrary Number of External Legs

We review recent progress in calculations of one-loop QCD amplitudes. By imposing the consistency requirements of unitarity and correct behavior as the momenta of two legs become collinear, we construct ansatze for one-loop amplitudes with an arbitrary number of external legs. For supersymmetric amplitudes, which can be thought of as components of QCD amplitudes, the cuts uniquely specify the amplitude.

hep-ph↗

arXiv1994

The Two-Jet Differential Cross Section at ${\cal O}(α_s^3)$ in Hadron Collisions

We study the two-jet inclusive cross section via the triply differential distribution $d^3σ/dE_{T}dη_1 dη_2$ to next-to-leading order in QCD. The predicted distributions can be compared directly with forthcoming data from the D0 and CDF experiments at Fermilab. We discuss differences with the leading-order predictions, and examine uncertainties due to the choice of scale and parton density.

hep-ph↗

arXiv1994

One-Loop n-Point Gauge Theory Amplitudes, Unitarity and Collinear Limits

We present a technique which utilizes unitarity and collinear limits to construct ansatze for one-loop amplitudes in gauge theory. As an example, we obtain the one-loop contribution to amplitudes for $n$ gluon scattering in $N=4$ supersymmetric Yang-Mills theory with the helicity configuration of the Parke-Taylor tree amplitudes. We prove that our $N=4$ ansatz is correct using general properties of the relevant one-loop $n$-point integrals. We also give the ``splitting amplitudes'' which govern the collinear behavior of one-loop helicity amplitudes in gauge theories.

hep-ph↗

arXiv1994

One-Loop N Gluon Amplitudes with Maximal Helicity Violation via Collinear Limits

We present a conjecture for the $n$-gluon one-loop amplitudes with maximal helicity violation. The conjecture emerges from the powerful requirement that the amplitudes have the correct behavior in the collinear limits of external momenta. One implication is that the corresponding amplitudes where three or more gluon legs are replaced by photons vanish for $n>4$.

hep-ph↗

arXiv1993

New QCD Results from String Theory

We discuss new results in QCD obtained with string-based methods. These methods were originally derived from superstring theory and are significantly more efficient than conventional Feynman rules. This technology was a key ingredient in the first calculation of the one-loop five-gluon amplitude. We also present a conjecture for a particular one-loop helicity amplitude with an arbitrary number of external gluons.

hep-th↗

arXiv1993

One-Loop Corrections to Five-Gluon Amplitudes

We present the one-loop helicity amplitudes with five external gluons. The computation employs string-based methods, new techniques for performing tensor integrals, and improvements in the spinor helicity method.

hep-ph↗

arXiv1992

Dimensionally Regulated One-Loop Integrals

We describe methods for evaluating one-loop integrals in $4-2\e$ dimensions. We give a recursion relation that expresses the scalar $n$-point integral as a cyclicly symmetric combination of $(n-1)$-point integrals. The computation of such integrals thus reduces to the calculation of box diagrams ($n=4$). The tensor integrals required in gauge theory may be obtained by differentiating the scalar integral with respect to certain combinations of the kinematic variables. Such relations also lead to differential equations for scalar integrals. For box integrals with massless internal lines these differential equations are easy to solve.

hep-ph↗

arXiv1992

The Five Gluon Amplitude and One-Loop Integrals

We review the conventional field theory description of the string motivated technique. This technique is applied to the one-loop five-gluon amplitude. To evaluate the amplitude a general method for computing dimensionally regulated one-loop integrals is outlined including results for one-loop integrals required for the pentagon diagram and beyond. Finally, two five-gluon helicity amplitudes are given.

hep-ph↗