Abstract
We investigate the possibilities of searching for a self-conjugate polarizable particle in the self-interactions of light. We first observe that polarizability can arise either from the exchange of mediator states or as a consequence of the inner structure of the particle. To exemplify this second possibility we calculate the polarizability of a neutral bosonic open string, and find it is described only by dimension-8 operators. Focussing on the spin-0 case, we calculate the light-by-light scattering amplitudes induced by the dimension-6 and 8 polarizability operators. Performing a simulation of exclusive diphoton production with proton tagging at the LHC, we find that the imprint of the polarizable dark particle can be potentially detected at 5σ significance for mass and cutoff reaching values above the TeV scale, for sqrt{s}=13 TeV and 300 fb−1 of integrated luminosity. If the polarizable dark particle is stable, it can be a dark matter candidate, in which case we argue this exclusive diphoton search may complement the existing LHC searches for polarizable dark matter.
Highlights
We investigate the possibilities of searching for a self-conjugate polarizable particle in the self-interactions of light
Performing a simulation of exclusive diphoton production with proton tagging at the LHC, we find that the imprint of the polarizable dark particle can be potentially detected at 5σ significance for mass and cutoff reaching values above the
If the polarizable dark particle is stable, it can be a dark matter candidate, in which case we argue this exclusive diphoton search may complement the existing LHC searches for polarizable dark matter
Summary
We use a low-energy effective field theory (EFT) approach. Here the set of CP-even polarizability operators up to dimension-8 is classified. We remark that the dimension-6 and 7 operators can be naturally suppressed with respect to the dimension-8 ones if the dark particle has an approximate shift-symmetry. When this happens, the dark particle mass should be suppressed . One can parametrize the explicit breaking of the shift-symmetry using the dark particle mass, and the dimension-6 (-7) operators are respectively suppressed by m2/Λ2, m/Λ and can be identified as the hatted operators of eq (2.4). This situation occurs for instance if the dark particle is the Nambu-Goldstone particle of a spontaneously broken approximate global symmetry, for example a U(n) symmetry or supersymmetry, respectively giving a Nambu-Goldstone scalar and a Nambu-Goldstini (see [39, 40] for a related analysis in the context of dark matter)
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