Pasterski–Strominger–Zhiboedov triangle

In theoretical physics, the Pasterski–Strominger–Zhiboedov (PSZ) triangle or infrared triangle is a series of relationships between three groups of concepts involving the theory of relativity, quantum field theory and quantum gravity. The triangle highlights connections already known or demonstrated by its authors, Sabrina Gonzalez Pasterski, Andrew Strominger and Alexander Zhiboedov.[1]

The connections are among weak and lasting effects caused by the passage of gravitational or electromagnetic waves (memory effects), quantum field theorems on graviton and photon and geometrical symmetries of spacetime. Because all of this occurs under conditions of low energy, known as infrared in the language of physicists, it is also referred to as the infrared triangle.[2]

Elements of the triangle

The concepts that are interconnected by the triangle are:

a) soft particle theorems (quantum field theory theorems regarding the behavior of low-energy gravitons or photons):
2. extension of the previous theorem, published by Freddy Cachazo and Strominger in 2014;[3]
3. soft photon theorem, also published by Weinberg in the same paper of 1965 regarding the graviton;
b) asymptotic symmetries (symmetries of spacetime distant from the sources of the fields):
1. supertranslations of the Bondi-Metzner-Sachs group, published in 1962;
2. superrotations (symmetry analogous to that of the Virasoro algebra), published by Glenn Barnich and Cédric Troessaert in 2010;[4]
c) memory effects:
1. gravitational memory effect, published by Yakov Zeldovich and A. G. Polnarev in 1974 and Demetrios Christodoulou in 1991;
2. new gravitational memory effects, published by Pasterski, Strominger and Zhiboedov in 2016;[6]
3. the electromagnetic analogue of the memory effect, published by Lydia Bieri and David Garfinkle in 2013.[7][8]

Binding relationships

Each group is linked to another by special relationships:

• Fourier transforms tie together soft theorems and memory effects;
• vacuum transitions tie together asymptotic symmetries and memory effects;
• Ward's identities tie together soft theorems and asymptotic symmetries.

So, for example:

• the soft graviton theorem (a.1) is related to the supertranslations (b.1) by a Ward's identity;
• the supertranslations (b.1) correspond to different vacuum states created by the gravitational memory effect (c.1)
• the gravitational memory effect (c.1) reduces to the soft graviton theorem (a.1) via a Fourier transform.[9]

In addition to the first triangular relationship highlighted by the authors, several others may exist and have been hypothesized.[10]

References

1. ^ Andrew Strominger (2018). Lectures on the Infrared Structure of Gravity and Gauge Theory. Princeton University Press. pp. 1–3.
2. ^ Infrared radiation has lower energies than visible radiation, so in physics it is often used as a synonym for low energy.
3. ^ Cachazo, Freddy; Strominger, Andrew (April 2014). "Evidence for a New Soft Graviton Theorem". arXiv:1404.4091 [hep-th].
4. ^ Barnich, Glenn; Troessaert, Cédric (2010-09-08). "Symmetries of Asymptotically Flat Four-Dimensional Spacetimes at Null Infinity Revisited". Physical Review Letters. 105 (11): 111103. arXiv:0909.2617. Bibcode:2010PhRvL.105k1103B. doi:10.1103/PhysRevLett.105.111103. PMID 20867563. S2CID 14678633. Retrieved 2023-07-27.
5. ^ Pasterski, Sabrina (2017-09-28). "Asymptotic symmetries and electromagnetic memory". Journal of High Energy Physics. 2017 (9): 154. arXiv:1505.00716. Bibcode:2017JHEP...09..154P. doi:10.1007/JHEP09(2017)154. S2CID 256041306. Retrieved 2023-07-26.
6. ^ Pasterski, Sabrina; Strominger, Andrew; Zhiboedov, Alexander (2016-12-14). "New gravitational memories". Journal of High Energy Physics. 2016 (12): 53. arXiv:1502.06120. Bibcode:2016JHEP...12..053P. doi:10.1007/JHEP12(2016)053. S2CID 256045385. Retrieved 2023-07-26.
7. ^ Bieri, Lydia; Garfinkle, David (2013-10-07). "An electromagnetic analogue of gravitational wave memory". Classical and Quantum Gravity. 30 (19): 195009. arXiv:1307.5098. Bibcode:2013CQGra..30s5009B. doi:10.1088/0264-9381/30/19/195009. S2CID 118728273. Retrieved 2023-07-26.
8. ^ Sarkkinen, Miika (2018). "Memory effect in electromagnetic radiation". s3.cern.ch. University of Helsinki - Physics Department. A passing gravitational wave periodically changes the relative distances of test particles, but after the wave has gone, there is no relative velocity between the particles. In the electromagnetic case, however, the memory effect is manifested as a "kick", a residual velocity imparted on a charge by the electromagnetic field.
9. ^ Strominger, Andrew; Zhiboedov, Alexander (2014). "Gravitational Memory, BMS Supertranslations and Soft Theorems". arXiv:1411.5745 [hep-th].
10. ^ Andrew Strominger (2018). Lectures on the Infrared Structure of Gravity and Gauge Theory. Princeton University Press. pp. 4–7.

Bibliography

• Andrew Strominger (2018). Lectures on the Infrared Structure of Gravity and Gauge Theory. Princeton University Press.