Question

In 2015, Strominger et al. showed that a result named for these particles was a Ward identity of certain BMS supertranslations. They’re not photons, but the change in the S matrix when a zero momentum one of these particles is added to a vertex is given by that result, which is Weinberg’s theorem on the “soft” examples of these particles. (15[1])Two-loop Feynman diagrams of interactions between these particles lead to ultraviolet (*) divergence, but one-loop diagrams are finite due to a Gauss–Bonnet counterterm. The self-interaction of these particles (-5[1])reproduces an action (-5[1])proportional to “square root of negative (-5[1])det g.” These particles are coupled (10[1])to the stress–energy tensor and hence are only radiated by quadrupole sources. (10[1])These (10[3])particles (10[1])correspond to (10[1])quantization (10[1])of the Einstein–Hilbert action. For 10 points, name these spin-2 massless particles that mediate the weakest fundamental force. ■END■

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