6
votes
Veneziano amplitude in quantum field theory
Well, it was understood early on,
H.B. Nielsen, P. Olesen, A Parton view on dual amplitudes,
Phys Lett B32 (1970) p. 203, and
B. Sakita, M.A. Virasoro, Dynamical model of dual amplitudes,
Phys Rev ...
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4
votes
How does one actually compute the amplituhedron?
Since this question, Arkani-Hamed among others has published the text, Grassmanian Geometry of Scattering Amplitudes which elucidates in a pedagogic fashion the amplituhedron approach.
To fully ...
- 19.5k
2
votes
Amplituhedron without SUSY
When the volume of the amplituhedron is calculated in the planar limit of N = 4 D = 4 supersymmetric Yang–Mills theory, it describes the scattering amplitudes of subatomic particles. The amplituhedron ...
- 235k
2
votes
Positive geometry and log singularities
I'm not sure I understood exactly what you want to know.
Anyhow, a positive geometry is an oriented geometry that has a canonical form. A canonical form is a differential form with dlog divergences, ...
- 31
2
votes
Accepted
Kinematics of Scattering Amplitudes in $\left(2, 2\right)$ Signature within the Amplituhedron
The main points are:
There is bijective isometry from the split-signature space $(\mathbb{R}^{2,2},||⋅||^2)$ to the space of $2\times 2$ real matrices $({\rm Mat}_{2\times 2}(\mathbb{R}),\det(⋅))$,
...
- 213k
2
votes
Accepted
Complex BCFW-shift of Parke-Taylor amplitude
The BCFW recursion relation is mainly used to recursively build connected $n$-point tree-amplitudes. The point of Exercise 3.3 in Ref. 1 is to check that the residue theorem works on the Riemann ...
- 213k
1
vote
Why does the amplitude not increase the speed of the sound wave?
You are mixing up two speeds, the speed at which "information" is transmitted from one molecule to the next (wave speed) and the speed of oscillation of a "molecule" about a "...
- 99.9k
1
vote
Why does the amplitude not increase the speed of the sound wave?
Increasing the kinetic energy of molecules in a gas means the temperature has to grow.
It is true that the speed of sound grows with temperature, see the measured change:
So the average kinetic ...
- 235k
1
vote
Questions about the plabic graphs in the amplituhedron program
The number of particles is equal to the number of external legs in the plabic graph.
The number of negative helicity particles is usually indicated by k and can be read from the permutation labelling ...
- 31
1
vote
What are the equations and constraints defining an/the Amplituhedron?
You could try the original paper: Arkani-Hamed, Nima; Trnka, Jaroslav (2014). "The Amplituhedron". Journal of High Energy Physics. 2014 (10): 30. arXiv preprint. See especially Section 9 for ...
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