The Amplituhedron

amplituhedron-drawing_webNima Arkani-Hamed, Jaroslav Trnka
Perturbative scattering amplitudes in gauge theories have remarkable simplicity and hidden infinite dimensional symmetries that are completely obscured in the conventional formulation of field theory using Feynman diagrams.
This suggests the existence of a new understanding for scattering amplitudes where locality and unitarity do not play a central role but are derived consequences from a different starting point.
In this note we provide such an understanding for N=4 SYM scattering amplitudes in the planar limit, which we identify as “the volume” of a new mathematical object–the Amplituhedron–generalizing the positive Grassmannian. Locality and unitarity emerge hand-in-hand from positive geometry.
Read more at http://arxiv.org/pdf/1312.2007v1.pdf

Read also: “Scientists Discover a Jewel at the Heart of Quantum Physics

(updated)
Read more: Into the Amplituhedron

Nima Arkani-Hamed: Why the Higgs Has to Exist

Nima Arkani-Hamed

Nima Arkani-Hamed

The Inevitability of Physical Laws: Why the Higgs Has to Exist
Nima Arkani-Hamed
Institute for Advanced Study
October 26, 2012 – 5:30pm
Our present framework for physics is difficult to modify without destroying its marvelous, successful properties. This provides a strong check on theoretical speculations and helps guide us to a small set of candidates for new laws. In this talk, Nima Arkani-Hamed, Professor in the School of Natural Sciences, illustrates these ideas in action by explaining why theoretical physicists knew the Higgs boson had to exist long before it was discovered at the Large Hadron Collider in July 2012. While the discovery of the Higgs is a triumph for both experimental and theoretical physics, its existence opens up a set of profound conceptual paradoxes, whose resolution is likely to involve radical new ideas. The talk concludes with a description of possible avenues of attack on these mysteries, and what we might learn from the LHC in this decade. http://video.ias.edu/arkani-hamed-lecture-10-12

Read also: The Future of Fundamental Physics

Arkani-Hamed: Idea of space and time needs to be replaced

A TOI exclusive with Dr Nima Arkani-Hamed, an American/Canadian theoretical physicist, who was an inaugural awardee of the Fundamental Physics Prize, the largest physics prize in the world worth $ 3 million, in July 2012. The scientist, currently with Institute for Advanced Study in Princeton, was recently at the IISC for delivering a series of lectures.

Q. What are your views on the possible discovery of Higgs particles?

It started as a very big idea that many people ran into around the same time. Higgs was not invented as a response to some strange complicated experimental observation but from the structures of the theories of physics. There are people trying to figure out the indirect effects between the different Higgs like particles. These are very difficult experiments and will take another 20 years before any confirmation is reached.

Q. How do you see the future of particle physics pan out?

What’s going on in particle physics is not just the evolution of the standard model but the rise of a new branch of physics that can solve some of the age old problems. Super symmetry is a very good example of what this physics should look like. For the first time we will have some evidence that there’s actually really fine adjustments of the parameters of fundamental physics hardwired into the way nature works. This will be very shocking for many people and teach us something profound. We are at a very interesting time, we don’t know what the answers are but we are moving towards them.

Q. Do you think there’s something beyond the Standard Theory?
There’s a whole bunch of things that aren’t explained within the standard model. We must conclude that the physics we are currently familiar with needs to be broken down. A standard model looks talks and walks exactly like an effective theory. But, it’s clearly not the final story.

Q. How do you see quantum mechanics evolve in the coming years?
Quantum mechanics has one of the most rigid theoretical structures that we have seen. People have tried for years to modify but haven’t found a theoretical consistency in their endeavor. So it is very hard to come up with new ideas that solves or attacks a problem, which isn’t just dead purely theoretically. However, most of theoretical physicists strongly consider that the idea of space and time needs to be replaced by deeper and more fundamental building blocks. We could also get some kind of extensions of Quantum Mechanics in future. If there’s some issue with quantum mechanics it is bound to arise with cosmological questions and we may have to find deeper theories quantum mechanics emerge from.

Q. String theory or standard model, which offers a better explanation to our quest to understand the universe?
In late 1990s one of the most important theoretical discoveries was that string theory and particle physics are not different but different descriptions of the same thing. All the good viable ideas people have had in the past 40 years are now branched together to seek the truth.

Q. Big Bang theory is an idea that has found a lot of acceptance among young science enthusiast, apart from scientists. What are your views on this regards?

There are different aspects of the big bang theory. Part of it has so many experimental confirmations that it is definitely correct. We now know that the universe is expanding. Some elements like helium and lithium couldn’t be made in stars but inside the furnace of big bang. Space and time bar are breaking down near the place where our equations are breaking down. We don’t know yet as to what exactly happened then but we have certain clues.

Q. Do you think awards like Fundamental Physics Award helps in creating more awareness about the subject?
I really think it’s a fantastic thing for Physics—to have a showcase every year where scientists get to talk about the exciting aspects of the subject. I don’t think any physicist or scientists are motivated to research by the thought of a prize or the money involved in it. But, it definitely helps in creating awareness among the youngsters, and encourages more people to take up the subject.

Read more: timesofindia.indiatimes.com