scholarly journals High Energy Scattering of Non-Critical Strings

1997 ◽  
Vol 12 (06) ◽  
pp. 1253-1263 ◽  
Author(s):  
Kenichiro Aoki ◽  
Eric D'Hoker

We summarize recent work, in which we consider scattering amplitudes of non-critical strings in the limit where the energy of all external states is large compared to the string tension. We show that the high energy limit is dominated by a saddle point that can be mapped onto an electrostatic equilibrium configuration of an assembly of charges associated with the external states, together with a density of charges arising from the Liouville field. The Liouville charges accumulate on line segments, which produce quadratic branch cuts on the worldsheet. The electrostatic problem is solved for string tree level in terms of hyperelliptic integrals and is given explicitly for the 3- and 4-point functions. For generic values of the central charge, the high energy limit behaves in a string-like fashion, with exponential energy dependence.

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
António Antunes ◽  
Miguel S. Costa ◽  
Tobias Hansen ◽  
Aaditya Salgarkar ◽  
Sourav Sarkar

Abstract We derive an optical theorem for perturbative CFTs which computes the double discontinuity of conformal correlators from the single discontinuities of lower order correlators, in analogy with the optical theorem for flat space scattering amplitudes. The theorem takes a purely multiplicative form in the CFT impact parameter representation used to describe high-energy scattering in the dual AdS theory. We use this result to study four-point correlation functions that are dominated in the Regge limit by the exchange of the graviton Regge trajectory (Pomeron) in the dual theory. At one-loop the scattering is dominated by double Pomeron exchange and receives contributions from tidal excitations of the scattering states which are efficiently described by an AdS vertex function, in close analogy with the known Regge limit result for one-loop string scattering in flat space at finite string tension. We compare the flat space limit of the conformal correlator to the flat space results and thus derive constraints on the one-loop vertex function for type IIB strings in AdS and also on general spinning tree level type IIB amplitudes in AdS.


2020 ◽  
Vol 2020 (8) ◽  
Author(s):  
Nathaniel Craig ◽  
Minyuan Jiang ◽  
Ying-Ying Li ◽  
Dave Sutherland

Abstract We consider aspects of tree and one-loop behavior in a generic 4d EFT of massless scalars, fermions, and vectors, with a particular eye to the high-energy limit of the Standard Model EFT at operator dimensions 6 and 8. First, we classify the possible Lorentz structures of operators and the subset of these that can arise at tree-level in a weakly coupled UV completion, extending the tree/loop classification through dimension 8 using functional methods. Second, we investigate how operators contribute to tree and one-loop helicity amplitudes, exploring the impact of non-renormalization theorems through dimension 8. We further observe that many dimension 6 contributions to helicity amplitudes, including rational parts, vanish exactly at one-loop level. This suggests the impact of helicity selection rules extends beyond one loop in non-supersymmetric EFTs.


Author(s):  
Chris White

Scattering amplitudes in quantum field theories are of widespread interest, due to a large number of theoretical and phenomenological applications. Much is known about the possible behaviour of amplitudes, that is independent of the details of the underlying theory. This knowledge is often neglected in modern QFT courses, and the aim of these notes - aimed at graduate students - is to redress this. We review the possible singularities that amplitudes can have, before examining the generic behaviour that can arise in the high-energy limit. Finally, we illustrate the results using examples from QCD and gravity.


2011 ◽  
Vol 26 (09) ◽  
pp. 603-623
Author(s):  
ANNA M. STASTO

We briefly review some selected topics in the small x physics. In particular, we discuss the progress in the problem related to the resummation at small x and the parton saturation phenomena. Finally we discuss some phenomenological applications to deep inelastic scattering, hadron and heavy ion collisions.


2004 ◽  
Vol 19 (36) ◽  
pp. 2655-2671 ◽  
Author(s):  
RIKARD ENBERG

I review work on diffractive vector meson production in photon–proton collisions at high energy and large momentum transfer, accompanied by proton dissociation and a large rapidity gap. This process provides a test of the high energy scattering dynamics, but is also sensitive to the details of the treatment of the vector meson vertex.The emphasis is on the description of the process by a solution of the non-forward BFKL equation, i.e. the equation describing the evolution of scattering amplitudes in the high-energy limit of QCD. The formation of the vector meson and the nonperturbative modeling needed is also briefly discussed.


Interest in the continuous β-ray spectrum has been revived during the past few years by the discovery of induced β-ray activity and the difficulty which has been experienced in incorporating an account of the phenomenon in the theory of the nucleus. Attention has been focused on two features of the spectrum: the high-energy limit, the accurate measurement of which yields the total change in nuclear energy associated with the β disintegration, and the form of the energy distribution curve, which is discriminative in theories of the β-ray emission process. Owing to the convenience of R aE as a source, the β-ray spectrum of this element has received considerable attention, and a comprehensive table of previous work published in a recent paper by O’Conor (1937) shows that recent values of the high-energy limit obtained with magnetic spectrometers are in fair agreement. The form of the R aE spectrum, however, is still not known with any certainty. This can be made clear with the help of Table I, which sets out the results and significant experimental details of the work carried out since 1935 with magnetic spectrometers. Some recent work with cloud expansion chambers is not included because the results are rather discordant. With the relatively low energy electrons of R aE and the high probability of nuclear collisions in the chamber, measurements of the energies of the β-particles are extremely difficult, and the results are probably not as reliable as those obtained with magnetic spectrometers.


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