Questions tagged [amplituhedron]
A geometric object whose volume is conjectured to be related to scattering amplitudes. It is used mostly in string theory.
25
questions
1
vote
0
answers
84
views
All possible QFTs from geometry? [closed]
Physicist Nima Arkani-Hamed has taken an approach to understand fundamental physics based on geometry (specifically, positive geometry). This started with his work with Jaroslav Trnka in the ...
- 1,526
0
votes
2
answers
90
views
Why does the amplitude not increase the speed of the sound wave?
The way I see it,if there's a set up A which has 5 particles and another set up B which also has 5 particles,and assuming everything else is same in these set up,like distance between particles etc,if ...
- 151
2
votes
1
answer
68
views
Positive geometry and log singularities
In order to define a positive geometry it is a requirement that has to be a logarithmic singularities on the boundaries, for example for an interval (endpoints $a$ and $b$) the canonical form is
$$\...
- 183
1
vote
1
answer
97
views
Kinematics of Scattering Amplitudes in $\left(2, 2\right)$ Signature within the Amplituhedron
I am just working my way through the concepts of Amplituhedron and often stumble across the phrase
[...] in $\left(2,2\right)$ signature $\lambda$, $\tilde{\lambda}$ are real and independent [...]
...
- 33
1
vote
0
answers
62
views
Differential forms in projective space
I am currently reading some paper about the Amplituhedron, and it is using projective geometric way to present amplitudes.
How can we define forms in projective space to measure volume for a polytope?
- 183
1
vote
0
answers
28
views
Question about an NHMV amplitude (in the book by Elvang et al) and its representation by plabic graphs
I am looking at the NMHV amplitude with six particles with three positive helicities (particles 1,3,5). This amplitude is given in Eq.(10.1), which is
[3,1,6,5,4]+[3,2,1,6,5]+[3,2,1,5,4]
My question ...
- 64
0
votes
1
answer
58
views
Questions about the plabic graphs in the amplituhedron program
I am reading the book by Arkani-Hamed et al. I see how one can get the permutation from a plabic graph, and I see how different plabic graphs can be shown to be equivalent through moves.
But I don't ...
- 64
1
vote
0
answers
47
views
Ordering ambiguity in the spinor helicity formalism of scattering amplitudes
I am following Nima's course on "Quantum mechanics and spacetime, total positivity and motives", and I wonder if there's a direct way to understand the ordering ambiguity when we are summing ...
1
vote
1
answer
271
views
Veneziano amplitude in quantum field theory
It is well-known, that Veneziano amplitude is the string scattering amplitude for the scattering of four open bosonic strings in their tachyon states.
Are some QFT models, in which amplitude is ...
- 5,509
1
vote
0
answers
73
views
How to derive a formula involves a delta function? [closed]
I watched the video: Geometry of scattering amplitudes of lectures by Nima Arkani-Hamed. At 3:00:00, he derived the following equation:
\begin{align}
& \int \frac{dc_1}{c_1} \cdots \frac{dc_5}{c_5}...
- 257
1
vote
1
answer
82
views
What are the equations and constraints defining an/the Amplituhedron?
No doubt we've all read quite a bit about amplituhedra in recent years, the best thing since sliced bread apparently for obtaining scattering amplitudes. But finding on the web formal definitions of ...
- 807
2
votes
1
answer
113
views
Amplituhedron without SUSY
I was reading around about the Amplituhedron (there are many topics on this SE or in other places for discussions outside this), and I was wondering, is supersymmetry required to make it work or to ...
- 466
1
vote
0
answers
143
views
How to prove that the scattering amlitude of bi-adjoint scalar field theory admits a Cachazo-He-Yuan (CHY) representation?
How to prove that the scattering amlitude of bi-adjoint scalar field theory admits a Cachazo-He-Yuan (CHY) representation?
- 942
1
vote
0
answers
151
views
Other spaces like Fourier space
Are there any other spaces like Fourier space in which one can more physical information than configuration space?
In a summer school about scattering amplitudes, someone told me that this relation ...
- 11
-1
votes
1
answer
202
views
Can elementary particles be abstractly represented as polytopes or geometric functions?
In Quantum Field Theory, elementary particles are represented like localized oscillations (localized transverse spherical standing waves) of their underlying fields, or superpositions of their normal ...
- 339
1
vote
0
answers
203
views
Is the Amplituhedron somehow equivalent to the S-matrix theory?
Amplituhedra are a family of spaces with the property that co-dimension one boundary of an Amplituhedron are the product of "smaller" Amplituhedra. In addition they are given a volume form that has a ...
- 1,990
2
votes
0
answers
146
views
Are new discoveries in quantum physics (e.g. Amplituhedron) supporting one of the classical QM interpretations? [closed]
Are new discoveries in quantum physics (e.g. Amplituhedron, Higgs boson) supporting one of the classical QM interpretations? For example Copenhagen, Everett many worlds or Penrose interpretations. Or ...
- 21
3
votes
1
answer
501
views
What is the meaning of the dlog integrations in the on-shell/grassmannian representation of N=4 SYM scattering amplitudes?
After reading part of this paper by Nima Arkani-Hamed, http://arxiv.org/abs/1212.5605, I cannot understand what is the precise meaning of the $dlog(\alpha)$ integrations.
Any on-shell diagram is ...
- 1,990
0
votes
0
answers
88
views
Notation for Propability Amplitudes
I've recently stumbled upon a certain piece of notation that doesn't quite seem clear to me. When discussing the amplituhedron, my teacher mentioned the relation between the volume and the amplitude ...
- 291
4
votes
1
answer
177
views
Relation between canonical forms and volume of polytopes
Références:
Ref $1$: Henriette Elvang, Yu-tin Huang: Scattering Amplitudes
Ref $2$: Jaroslav Trnka: The Amplituhedron
[For simplicity, the notations of the $2$ refs have been merged]
The area of a ...
- 17.3k
0
votes
0
answers
333
views
What happens to the amplituhedron in a non-peturbative context?
The Amplituhedron has recently been popular; it supposedly encodes perturbative scattering amplitudes in a simple, geometric fashion.
What happens to it in a non-perturbative context? Is there ...
- 6,072
5
votes
1
answer
2k
views
What is known on violations of unitarity or locality?
Recently the amplituhedron become a hot topic. I realized that two of the central pillars that QFT is based on, unitarity and locality, are no longer playing an important part (due to gravitational ...
- 1,537
7
votes
2
answers
2k
views
How does one actually compute the amplituhedron?
I was watching Nima's very popular talk (download if you're using chrome) (also mirrored at youtube here) about the "Amplituhedron", which has suddenly become very popular recently.
He talks all ...
- 6,072
7
votes
1
answer
561
views
Is integrability necessary for the Amplituhedron?
It is well known that there exist mappings between operators in N = 4 Super Yang–Mills and spin chain states making the theory Bethe Ansatz integrable. Is integrability a necessity for the ...
- 2,010
114
votes
5
answers
33k
views
What is the actual significance of the amplituhedron?
The news that physicists have discovered a geometrical object that simplifies a lot our models of quantum physics has recently became viral. For an outsider like me, it is difficult to actually ...
- 1,952