Physics – Nuclear Physics – Nuclear Theory
Scientific paper
1992-10-12
Physics
Nuclear Physics
Nuclear Theory
49 pages report # LA-UR-92-2702
Scientific paper
10.1103/PhysRevC.47.973
A modified Low procedure for constructing soft-photon amplitudes has been used to derive two general soft-photon amplitudes, a two-s-two-t special amplitude $M^{TsTts}_{\mu}$ and a two-u-two-t special amplitude $M^{TuTts}_{\mu}$, where s, t and u are the Mandelstam variables. $M^{TsTts}_{\mu}$ depends only on the elastic T-matrix evaluated at four sets of (s,t) fixed by the requirement that the amplitude be free of derivatives ($\partial$T/$\partial$s and /or $\partial$T/$\partial t$). Likewise $M^{TuTts}_{\mu}$ depends only on the elastic T-matrix evaluated at four sets of (u,t). In deriving these amplitudes, we impose the condition that $M^{TsTts}_{\mu}$ and $M^{TuTts}_{\mu}$ reduce to $\bar{M}^{TsTts}_{\mu}$ and $\bar{M}^{TuTts}_{\mu}$, respectively, their tree level approximations. The amplitude $\bar{M}^{TsTts}_{\mu}$ represents photon emission from a sum of one-particle t-channel exchange diagrams and one-particle s-channel exchange diagrams, while the amplitude $\bar{M}^{TuTts} _{\mu}$ represents photon emission from a sum of one-particle t-channel exchange diagrams and one-particle u-channel exchange diagrams. The precise expressions for $\bar{M}^{TsTts}_{\mu}$ and $\bar{M}^{TuTts}_{\mu}$ are determined by using the radiation decomposition identities of Brodsky and Brown. We point out that it is theoretically impossible to describe all bremsstrahlung processes by using only a single class of soft-photon amplitudes. At least two different classes are required: the amplitudes which depend on s and t or the amplitudes which depend on u and t. When resonance effects are important, the amplitude $M^{TsTts}_{\mu}$, not $M^{Low(st)}_{\mu}$, should be used. For processes with strong u-channel exchange effects, the amplitude $M^{TuTts}_{\mu}$ should be the first choice.
Gibson Benjamin F.
Lin Dahang
Liou M. K.
No associations
LandOfFree
Anatomy of the Soft-Photon Approximation in Hadron-Hadron Bremsstrahlung does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Anatomy of the Soft-Photon Approximation in Hadron-Hadron Bremsstrahlung, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Anatomy of the Soft-Photon Approximation in Hadron-Hadron Bremsstrahlung will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-584667