Narrow Results

In this paper, we consider the processes of single top-quark production in association with dark matter particles through the t-channel in simplified models with scalar and pseudoscalar mediators. Within the framework of these models, we analyze the angular correlations that arise in the top quark production process in association with dark matter, comparing them with the production of a top quark in the Standard Model. We consider angular correlations of kinematic variables, which define admissible regions in momentum space and can be used experimentally to distinguish between the fraction of the total momentum carried away by the scalar or pseudoscalar mediator. We demonstrate that scalar mediator significantly changes the rest frame of the well-known angular correlation observable and changes the distributions. In this case, this variable provides clear separation between the SM and DM contribution and can be used to increase the sensitivity of future DM analyses.

Resonances observed in the ²⁸Si + ²⁸Si collision are studied by a molecular model. At high spins, a stable dinuclear configuration is found to be equator-equator touching one. Energy spectrum of the normal modes around the equilibrium is shown. These modes are expected to be the origin of the large number of resonances observed, hence theoretical analyses for the physical quantities are done. Disalignments between the orbital angular momentum and the fragment spins in the resonance state are clarified. Moreover the analyses of the angular correlations indicate a characteristic feature for each normal-mode excitation. Thus it is possible to identify the mode.