# Would the Standard Model allow two energetic photons to form a particle-like, zero-spin resonance?

The title is the question: Would the Standard Model allow two energetic photons to form a particle-like, zero-spin resonance?

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Sure. Neutral pions do it all the time. Look for 2-gamma decay of the $\pi^0$. Here's a quick article to get you started: http://arxiv.org/abs/1206.1375 And if a neutral pion can decay into two photons, then the opposite reaction is also possible.