Research Interests


My research can be divided into two components: thinking particle phenomenology in astrophysics context(dark matter, neutrino physics, etc.); using exotic tools to understand beyond the Standard Model physics (noncommutative geometry, biorthogonal quantum mechanics, and quantum measurement).


Dark matter

Dark matter (DM) is one of the most intriguing problems in particle physics and cosmology. Understanding the nature of DM will definitely shed light on the most fundamental questions of both. Evidence from galaxies and clusters (rotation curves, gravitational lensing, bullet cluster, hot gas,) and relic abundance (CMB, nucleosynthesis,) supports the very existence of DM. On the other hand, we try to model DM, or say, to use the observational data to verify each and every model we can think of. With data being accumulated from both astrophysical observatories and particle experiments, we are at a time to relate and combine constraints from many different sectors, to put the most stringent bounds on some of the DM models than ever before.

 

Neutrino phenomenology

Our recent understanding of neutrinos (mass, mixing angle, etc.) has improved a lot. However, determined by the nature of the weak interaction, it is still one of the particle sectors that are less well understood. There is a chance that non-standard interactions (NSI) are present but hidden within the uncertainty of current measurement. We are working on a universal analytical tool to parametrize NSI in matter effect, in the hope of giving NSI effect a clear physical picture and making degeneracy analysis more straightforward. Besides, with DUNE being on top of the list, models with large NSI emerge. It is interesting to figure out what parameter space is actually left for large NSI within DUNE reach. This may provide general guidance for such model building.

 

Beyond the Standard Model (SM) through the Noncommutative Geometry (NCG)

The SM's validity in regards to various precision measurements of different processes and its robustness against any deformations remain unexplained. Attempts to reproduce and to justify the SM have been made in the past few decades. So far no concrete experimental evidence to prefer any models that extend the SM. As an alternative framework, the NCG provides a different perspective that may lead to new understandings of the SM. The idea is to generalize the ordinary geometry and to include the SM as part of the space-time structure. This might address conceptual questions like the picture of quantization, the principle that dictates the SM and provides a different way to look at the hierarchy problem. Also, in phenomenology model building, it turns out to be a framework more restrictive, thus more predictive.

 

Quantum foundation

As a prescription, quantum mechanics has been long tested and verified by experimentations. However, a deep understanding of the nature of quantum, or whether even such an understanding exists, is not reached. As a few of the unanswered questions, it is not understood what exactly happens to the system during the process of measurement, and it is not clear how the `collapse' happens in regards to this process if it is not treated as being `instantaneous.' Also, not much is known for the physical picture of taking quantum to classical beyond formally making Planck constant zero and changing the commutator to Poisson bracket. In principle, both the classical limit and quantum measurement should be related to the size of the observer and that of the system being observed. Since there is already a working example, quantum mechanics, one strategy to understand how the enigma works is to deform part of the mathematical structure and check the physical consequences. It is similar to the philosophy of studying genetics through mutation in biology. The study may be useful for understanding quantum further, as well as for quantum applications like quantum computation, etc.