# What's the recent released 750GeV particle's spin?

I was told that it has recently been confirmed to be spin-2 particle, and potentially to be graviton. I'm pretty interested in how this has been examined.

Edit: During the Moriond 2016 conference, CMS clearly stated it is a spin-2 rather than spin-0 particle (spin-1 has already been ruled out by Landau-Yang theorem [1-2]). For a review, see [3].

The yesterday report on ATLAS claims new analysis and new methods gave promising result, which is what I'm looking forward to know. Also I would like some experts to give an introduction to the physics picture how to examine the spin, and what's the theoretical model [4] means.

Edit2: on Aug 5th, ICHEP conference, the new result is gonna to be published.

Edit3: ICHEP conference released ATLAS & CMS results [5-6]. ATLAS doesn't contain newest spin-2 selection results (which could be something), while CMS gives disappointing results.

[1] C.-N. Yang, Selection Rules for the Dematerialization of a Particle Into Two Photons, Phys. Rev. 77 (1950) 242–245. http://dx.doi.org/10.1103/PhysRev.77.242;

[2] L. D. Landau, On the angular momentum of a system of two photons, Dokl. Akad. Nauk Ser. Fiz. 60 (2) (1948) 207–209. http://dx.doi.org/10.1016/B978-0-08-010586-4.50070-5.

[3] Strumia, Alessandro. "Interpreting the 750 GeV digamma excess: a review." arXiv preprint arXiv:1605.09401 (2016).

[4] Dillon, Barry M., and Veronica Sanz. "A little KK graviton at 750 GeV." arXiv preprint arXiv:1603.09550 (2016).

• I am surprised, as I know the graviton should be massless and in many aspects similar to the photon (f.e. $E=h\nu$). – peterh Jul 21 '16 at 20:50
• @peterh yes, but the proposed K-K theory give rises to a possible nonzero mass, as in ref [4] – RoderickLee Jul 21 '16 at 20:59
• A mirage in the desert – Count Iblis Jul 21 '16 at 22:02
• @peterh These are not 4D massless gravitons.. rather Kaluza-Klein type of gravitons, which are massive. For the diphoton, spin-0 or spin-2 are both possible... though we dont expect much from ICHEP now... the excess seem to have gone. Pity. – xi45 Jul 25 '16 at 23:11
• @xi45 The excess was there. But... something made it disappear. This is quite sad. Maybe it still exists in a different eigenfunction of our universes Hamiltonian. – peterh Jul 25 '16 at 23:19

The abstract for your third reference has a Particle Data Group block which gives $J=0$, but without much confidence. A footnote on page 5 of that reference expresses skepticism that it's a graviton.