Search

Highly boosted axion-like particles decaying into photon pairs are notoriously hard to detect at the LHC. The collimated decay photons cannot be individually reconstructed using only electromagnetic calorimeter information, making the signal less distinguishable from background. In this note we propose a search strategy to address this issue, exploiting the fact that a fraction of the decay photons convert into electron-positron pairs inside the tracking detector. The resulting tracks can be resolved with high resolution, allowing to separate the two collimated photons and resolve a displaced decay vertex. To demonstrate the effectiveness of this approach, we apply it to ALPs in the challenging MeV-GeV range produced via vector boson fusion. We find that such a search could give sensitivity to untested parameter space., Comment: 29 pages, 11 figures. Comments welcome

International audience; This work employs the technique known as sparse identifica-tion of nonlinear dynamics (SINDy) to infer, from a set of informationprovided by a given time-series, the evolution law of a dynamical systemof interest, accessing the physical consistency of the obtained dynamicmodel. The Duffing oscillator is used as a benchmark due to the vari-ety and richness of its dynamical behavior. The numerical experimentsattempt to identify whether the method is capable of recognizing thecorrect evolution law and respecting basic principles of physics such asthe balance of momentum and energy. The numerical results illustratethe method’s ability to obtain approximations to the system evolutionlaw that provides physically consistent behavior for short time intervals.

In this work, prospects to probe an overlooked facet of axion-like particles (ALPs) -- their potential couplings to sterile neutrinos -- are presented. We found that mono-photon searches have the potential to constrain ALP couplings to sterile neutrinos when a new heavy scalar boosts the ALP decay yields. Working within an effective field theory (EFT) approach, we scan the parameters space to establish the reach of the 13 TeV LHC to probe such couplings. We found regions of the parameters space evading several experimental constraints that can be probed at the LHC. Moreover, a complementary role between the LHC and various experiments that search for axions and ALPs can be anticipated for models where ALPs interact with sterile neutrinos. We also present the UV realization of a model having an axion-like particle, a heavy scalar and sterile neutrinos whose parameters are spanned by our EFT approach. The proposed model contains a type of seesaw mechanism for generating masses for the active neutrinos along with sterile neutrinos involving the high energy scale of the spontaneous breaking of the global symmetry associated to the ALP. Some benchmark points of this model can be discovered at the 13 TeV LHC with 300 fb$^{-1}$., Comment: 45 pages, 14 figures