Bethe Postdoctoral Fellowship

Current Fellow

Sungwoo Hong

Education

• B.S., Physics, Yonsei University, Seoul, Korea, 2010
• M.S., Physics, Carnegie Mellon University, Pittsburgh, PA, 2011
• Ph.D., Physics, University of Maryland, College Park, MD, 2017
• Hans Bethe Postdoctoral Fellow, LEPP, Cornell University, Ithaca, NY, 2017 - Present

Current Research

My primary research is in elementary particle theory and dark matter physics. In particular, I have been interested in understanding constraints that current experiments impose on best motivated frameworks, e.g. extra-dimensions for particle physics and CDM model for cosmology, and in developing new or extended frameworks that can address those issues.

The discovery of the Standard Model (SM) like Higgs boson in 2012, while celebrating the great success of the SM of particle physics, reinforced the puzzle of the gauge-Planck hierarchy problem. At the same time, the absence of new physics signals from low-energy precision and high-energy discovery experiments appears as a serious challenge to the majority of Beyond the Standard Model (BSM) frameworks. In particular, such circumstances suggest that little hierarchy may exist, although new physics at the TeV scale being at the cusp of discovery at the LHC remains as a strongly motivated possibility. A generalization of the standard Randall-Sundrum (RS) model was proposed in [1], addressing these issues. It was shown that the form of expected new physics at the TeV scale is, via AdS/CFT correspondence, that of vector-like confinement. Experimental searches for such new physics require new strategies due to new process topology and new boosted objects. Development of such new search strategies and detailed phenomenological studies were performed in [2, 3].

On the cosmology side, within the context of hidden WIMP (weakly interacting massive particle), in [4] it is argued that light species in the hidden sector are required in order to obtain observed abundance of the dark matter and that they can imprint several observables in CMB (Cosmic Microwave Background). It was pointed out that a set of observables from CMB can be used to determine the number of free-streaming and scattering light species separately. In addition, a robust model-independent lower bound for extra radiation degrees of freedom encoded in
ΔNeff was derived and such ultimate lower bound can be tested in upcoming experiments like CMB stage-VI.

The experimental anomalies that CDM is in tension with measurements on large scales had motivated another study to speculate about a beyond the CDM framework. A new dark matter framework called "partially acoustic DM", was proposed in [5], and it was shown that it can naturally resolve these puzzles and predicts distinguished pattern of Large Scale Structure (LSS) formation and yet being easily consistent with current LSS and CMB constraints.

Publications

1) K. Agashe, P. Du, S. Hong and R. Sundrum, \Flavor Universal Resonances and Warped Gravity," JHEP 1701, 016 (2017) doi:10.1007/JHEP01(2017)016 [arXiv:1608.00526 [hep-ph]].

2) K. S. Agashe, J. Collins, P. Du, S. Hong, D. Kim and R. K. Mishra, \LHC Signals from Cascade Decays of Warped Vector Resonances," JHEP 1705, 078 (2017) doi:10.1007/JHEP05(2017)078 [arXiv:1612.00047 [hep-ph]].

3) K. Agashe, J. H. Collins, P. Du, S. Hong, D. Kim and R. K. Mishra, \Dedicated Strategies for Triboson Signals from Cascade Decays of Vector Resonances," arXiv:1711.09920 [hep-ph].

4) Z. Chacko, Y. Cui, S. Hong and T. Okui, \Hidden dark matter sector, dark radiation, and the CMB," Phys. Rev. D 92, 055033 (2015) doi:10.1103/PhysRevD.92.055033 [arXiv:1505.04192 [hep-ph]].

5) Z. Chacko, Y. Cui, S. Hong, T. Okui and Y. Tsai, \Partially Acoustic Dark Matter, Interacting Dark Radiation, and Large Scale Structure," JHEP 1612, 108 (2016) doi:10.1007/JHEP12(2016)108 [arXiv:1609.03569 [astro-ph.CO]].