Physics beyond the standard model
AMO physics meets fundamental physics
In our group, we study the possibility of finding new physics beyond the standard model through atomic and molecular systems. In particular, we exploit the capability of controlling internal degrees of freedom in molecules to propose novel detectors for the search of light dark matter. In the same vein, we employ the remarkable precision of spectroscopy of atoms and molecules to constrain existing boundaries on different theoretical models regarding new physics.
Molecules and atoms as dark matter detectors
Observations from radial velocity curves in galaxies, galactic velocities in clusters of galaxies, and the temperature anisotropies of the cosmic microwave background (CMB) point towards the existence of dark matter. In particular, the CMB measurement established that around 24% fo the energy budget of the universe is in the form of dark matter. In contrast, only 4.6% is baryonic model matter. The astrophysical observations show that dark matter feels the gravitational force. However, the observations do not reveal any physics regarding the particle nature of dark matter. Therefore, experiments based on interactions beyond the gravitational force are needed to elucidate the ultimate particle dark matter nature.
In our group, we study atomic and molecular systems that may be potential candidates to detect dark matter with mass below the proton mass. The exploration in such a mass range is possible thanks to the energy scale associated with the internal degrees of freedom of the molecules. In particular, vibrational degrees of freedom in diatomic molecules shows an energy scale of the order of 0.5 eV. Assuming a typical dark matter speed of 600 km/s, the excitation of vibrational quanta in molecules will correlate with dark matter masses of the order of 100 MeV. Indeed, this sensitivity to light dark matter particle masses is hardly achievable in accelerator-based experiments. Therefore, our research is complementary to the ongoing research in the high energy physics community.
High precision spectroscopy to constrain the existence of new physics
The standard model of particle physics is the most successful theory for the fundamental forces of nature except for gravity. However, it does not answer questions like: what is dark matter? or what is the origin of the neutrino masses? Thus, new theoretical models need to be developed and tested, which are known as physics beyond the standard model. As an example of physics beyond the standard model, we present the typical pair annihilation into two photons. However, one of the photons is dark, has mass, and decays into a pair of dark matter particle-antiparticle.
The spectra of atoms and molecules, ultimately, are the consequence of the interaction between baryons and leptons. In our group, we study how physics beyond the standard model affects atomic and molecular spectroscopy data. In particular, one uses the precision on the spectroscopic data to constrain the parameter space relevant for physics beyond the standard model. Among the different candidates, we use exotic atoms like positronium (Ps) or muonium (pµ-).