Tenure-track Associate Professor

- Email:
- diedachung@sjtu.edu.cn

- particle physics beyond the Standard Model
- field theory
- gravity and cosmology

- “Void alignment and density profile applied to measuring cosmological parameters”, De-Chang Dai, Published in Monthly Notices of the Royal Astronomical Society 2015 454 (4): 3590-3596, doi: 10.1093/mnras/stv2208, eprint:arXiv:1509.07498
- “Using quasars as standard clocks for measuring cosmological redshift”, De-Chang Dai, Glenn D. Starkman, Branislav Stojkovic, Dejan Stojkovic, Amanda Weltman, Published in Phys. Rev. Lett 108, 231302 (2012), e-print: arXiv:1204.5191
- ”Vanishing Dimensions and Planar Events at the LHC”, Luis Anchordoqui, De Chang Dai, Malcolm Fairbairn, Greg Landsberg, Dejan Stojkovic, Published in Mod. Phys. Lett. A27 (2012) 1250021, e-Print: arXiv:1003.5914 [hep-ph]
- ”Analytic solution for a static black hole in RSII model.”, De-Chang Dai, Dejan Stojkovic, Published in Phys.Lett. B: 704, 354-359 (2011), e-Print: arXiv:1004.3291 [gr-qc]
- ”Measuring the cosmological bulk flow using the peculiar velocities of supernovae.”, De-Chang Dai, William H. Kinney, Dejan Stojkovic, Published in JCAP, 1004, 015 (2011), e-Print: arXiv:1102.0800 [astro-ph.CO]
- ”Searching for the Layered Structure of Space at the LHC.”, Luis A. Anchordoqui, De Chang Dai, Haim Goldberg, Greg Landsberg, Gabe Shaughnessy, Dejan Stojkovic, Thomas J. Weiler, Published in Phys. Rev. D, 83, 114046 (2011), e-Print: arXiv:1012.1870 [hep-ph]
- ”Analytic explanation of the strong spin-dependent amplification in Hawking radiation from rotating black holes.”, De-Chang Dai, Dejan Stojkovic, Published in JHEP: 1008, 016 (2010), e-Print: arXiv:1008.4586 [gr-qc]
- ”Time dependent fluctuations and particle production in cosmological de Sitter and anti-de Sitter spaces.”, Eric Greenwood, De-Chang Dai, Dejan Stojkovic, Published in Phys. Lett. B: 692, 226-231 (2010), e-Print: arXiv:1008.0869 [astro-ph.CO]
- ”Electroweak stars: How nature may capitalize on the standard model’s ultimate fuel.”, De-Chang Dai, Arthur Lue, Glenn Starkman, Dejan Stojkovic, Published in JCAP: 1012, 004 (2010), e-Print: arXiv:0912.0520 [hep-ph]
- ”Unparticle dark energy.”, De-Chang Dai, Sourish Dutta, Dejan Stojkovic, Published in Phys. Rev. D: 80, 063522 (2009), e-Print: arXiv:0909.0024 [astro-ph.CO]
- ”Constraints on dark matter particles charged under a hidden gauge group from primordial black holes.”, De-Chang Dai, Katherine Freese, Dejan Stojkovic, Published in JCAP: 0906, 023 (2009), e-Print: arXiv:0904.3331 [hep-ph]
- ”Neutralino dark matter stars can not exist.”, De-Chang Dai, Dejan Stojkovic, Published in JHEP: 0908, 052 (2009), e-Print: arXiv:0902.3662 [hep-ph]
- ”Hawking radiation of unparticles.”, De-Chang Dai, Dejan Stojkovic, Published in Phys. Rev. D: 8, 064042 (2009), e-Print: arXiv:0812.3396 [gr-qc]
- ”Limited utility of Birkhoff’s theorem in modified Newtonian dynamics: Nonzero accelerations inside a shell.”, De-Chang Dai, Reijiro Matsuo, Glenn Starkman, Published in Phys. Rev. D: 81, 024041 (2010), e-Print: arXiv:0811.1565 [astro-ph]
- ”Gravitational Lenses in Generalized Einstein-Aether theory: The Bullet Cluster.”, De-Chang Dai, Reijiro Matsuo, Glenn Starkman, Published in Phys. Rev. D: 78, 104004 (2008), e-Print: arXiv:0806.4319 [gr-qc]
- ”BlackMax: A black-hole event generator with rotation, recoil, split branes, and brane tension.”De-Chang Dai, Glenn Starkman, Dejan Stojkovic, Cigdem Issever, Eram Rizvi, Jeff Tseng, Published in Phys. Rev. D: 77,076007 (2008), e-Print: arXiv:0711.3012 [hep-ph]
- ”Consequences of the absence of Birkhoff’s theorem in modified-gravity theories: The Dvali-Gabadaze-Porrati model.” De-Chang Dai, Irit Maor, Glenn D. Starkman, Published in Phys. Rev. D: 77, 064016 (2008), e-Print: arXiv:0709.4391 [gr-qc]
- ”Evaporation of a black hole off of a tense brane.” De-Chang Dai, Nemanja Kaloper, Glenn D. Starkman, Dejan Stojkovic, Published in Phys. Rev. D: 75, 024043 (2007), e-Print: hep-th/0611184
- ”Production of black holes and their angular momentum distribution in models with split fermions.” De-Chang Dai, Glenn D. Starkman, Dejan Stojkovic, Published in Phys. Rev. D: 73, 104037 (2006), e-Print: hep-ph/0605085
- ”Why black hole production in scattering of cosmic ray neutrinos is generically suppressed.” Dejan Stojkovic, Glenn D. Starkman, De-Chang Dai, Published in Phys. Rev. Lett.: 96,041303 (2006), e-Print: hep-ph/0505112
- ”Solar-Cycle Variations of Subsurface meridional Flow in the sun” Chou, D.-Y., Dai, D.-C.Published in Astrophysical Journal Letter, 559, L175 (2001)
- ”Lifetimes of High-l solar p-modes from Time-Distance Analysis” Chou, D.-Y., Serebryansky A., Ye, Y.-J., Dai, D.-C.Published in Astrophysical Journal Letter, 554, L229

My research focuses on particle physics beyond the Standard Model, gravity and cosmology. Below, I review the main topics of my present and future research interests, mostly on the interface of particle physics and cosmology:

**Bulk Flow**: The bulk flow is the last puzzle raised by the cosmological observational data. This is a coherent motion of a large part of our visible universe in a particular direction. Originally, it was claimed by Kashlinsky et al. by using the Suyaev-Zel’dovich effect in the Cosmic Microwave Background (CMB) radiation. This result was later reinforced by using a compilation of peculiar velocity redshift surveys. This analysis showed a large bulk flow which conflict with the Lambda-CDM expectation. Though the directions of the bulk flow are very consistent, the magnitudes of the bulk flow velocities are less consistent and vary from analysis to analysis. To verify independently if the bulk flow is real we studied the peculiar velocities of Type IA supernovae. If the bulk flow is real, then some imprint must be left on supernovae motion. Since the recession velocities of the high redshift supernovae are large and the magnitude of the bulk flow is moderate, one can expect the largest contribution to come from the low redshift supernovae. Our results are consistent with this expectation. Therefore, there is no clear conflict between peculiar velocity flow and Lambda-CDM.

**Modified Gravity**: The Lambda-CDM model is the current paradigm in cosmology. This model can explain a wide range of observations, but it is also not free of problems. Two of the most acute problems are the introduction of exotic forms of energy density – the dark matter and the dark energy. Since these forms of energy have never been observed in a laboratory, some theorists have begun looking for other options. For example, the MOND theory can replace dark matter in the galaxy, and the f(R) theory might explain the dark energy. These models modify either Newtonian gravity or General Relativity. Some of the important characteristics of GR or Newtonian theory are lost; most notably there is a violation of the conditions of Birkhoffs theorem. If Birkoff’s theorem is violated, one may need to know the distribution of all the mass in the universe, in order to calculate the gravitational force in each neighborhood. This would make a simple Newtonian system very difficult to treat.

**Physics beyond standard model**: The Standard Model of the strong, weak and electromagnetic interactions agrees well with experimental data. However it also leaves several problems unsolved; for example, there are at least 20 unexplained parameters some of which are beyond today’s experimental reach. There are many new models having been developed to replace or extend the Standard model, include SUSY, technicolor, extra dimensions and so on.