Phase Transitions and Topological Defects in the Early Universe

On August 2–5, the CMSA will host a workshop on Phase Transitions and Topological Defects in the Early Universe.

The workshop will be held in room G10 of the CMSA, located at 20 Garden Street, Cambridge, MA and online via Zoom webinar.

The next decade will see a wealth of new cosmological data, which can lead to new insights into fundamental physics. Upcoming facilities (such as LISA) will be able to probe signals of fascinating phenomena in the early universe. These include signals from “Phase Transitions and Topological Defects,” which are ubiquitously given rise to in well-motivated UV models. In-depth studies of such signals requires cross-talks between experts from a wide spectrum of fields. 

The workshop aims to provide a platform for efficient exchange of new ideas related to these topics. It will start with an overview of some of the past and future experimental efforts. Next, there will be a substantial number of talks probing different aspects of phenomenology of phase transitions and topological defects in the early universe. It will finally close with discussions on recent formal development in the field.

Scientific Advisory: Julian B. Muñoz, Lisa Randall, Matthew Reece, Tracy Slatyer, Shing-Tung Yau

Harvard: Nick DePorzio, Katie Fraser, Sam Homiller, Rashmish Mishra, & Aditya Parikh
MIT: Pouya Asadi, Marianne Moore, & Yitian Sun

There will be 20+ 10 minute talks, ample discussion time, and lightning chalkboard talks.

In-person registration

Location: Room G10, CMSA, 20 Garden Street, Cambridge, MA 02138

All non-Harvard affiliated visitors to the CMSA building are required to complete this covid form prior to arrival:

In-person registration is at capacity.
If you are interested in attending please contact: Pouya Asadi 

For a list of lodging options convenient to the Center, please see the recommended lodgings page.

Virtual registration

Zoom webinar:
Zoom registration is required to receive the link.
Register here to attend virtually.


  • Nancy Aggarwal (Northwestern)
  • Jae Hyeok Chang (UMD – JHU)
  • Yanou Cui (UC Riverside)
  • David Dunsky (UC Berkeley)
  • Isabel Garcia-Garcia (KITP – UCSB)
  • Oliver Gould (Nottingham)
  • Yann Gouttenoire (Tel Aviv)
  • Eleanor Hall (UC Berkeley)
  • Sungwoo Hong (Chicago)
  • Anson Hook (UMD)
  • Jessica Howard (UC Irvine)
  • Seth Koren (Caltech)
  • Mrunal Korwar (Wisconsin)
  • Soubhik Kumar (UC Berkeley)
  • Vuk Mandic (Minnesota)
  • Yuto Minami (Osaka)
  • Adam Moss (Nottingham)
  • Michael Nee (Oxford)
  • Kai Schmitz (CERN)
  • Stephen R. Taylor (Vanderbilt)
  • Ofri Telem (UC Berkeley)
  • Yikun Wang (Caltech)


  • Manuel Buen Abad (UMD)
  • Pouya Asadi (MIT)
  • Sean Benevedes (MIT)
  • Sandipan Bhattacherjee (Birla Institute of Technology Mesra Ranchi India)
  • Xingang Chen (Harvard University)
  • Nicholas DePorzio (Harvard University)
  • Peizhi Du (Stony Brook University)
  • Nicolas Fernandez (University of Illinois Urbana-Champaign)
  • Joshua Foster (MIT)
  • Katherine Fraser (Harvard University)
  • Sarah Geller (MIT)
  • Aurora Ireland (University of Chicago)
  • Marius Kongsore (New York University)
  • Ho Tat Lam (Massachusetts Institute of Technology)
  • Lingfeng Li (Brown University)
  • Yingying Li (Fermilab)
  • Gustavo Marques-Tavares (UMD)
  • Rashmish Mishra (Harvard University)
  • Siddharth Mishra-Sharma (MIT/Harvard University)
  • Toby Opferkuch (UC Berkeley)
  • Tong Ou (University of Chicago)
  • Aditya Parikh (Harvard University)
  • Yitian Sun (MIT)
  • Juan Sebastian Valbuena-Bermudez (Ludwig Maximilian University of Munich and Max Planck Institute for Physics)
  • Isaac Wang (Rutgers)
  • Yikun Wang (California Institute of Technology)
  • Wei Xue (University of Florida)
  • Winston Yin (UC Berkeley)
  • Quratulain Zahoor (The Islamia University of BahwalpurPunjab (Pakistan)


August 2, 2022

9:00–9:30 amBreakfast
9:30–11:00 amTalks
11:00–1:30 pmLunch break
1:30–4:00 pmDiscussions and Talks

August 3, 2022

9:00–9:30 amBreakfast
9:30–11:00 amTalks
11:00–1:30 pmLunch break
1:30–4:00 pmDiscussions and Talks

August 4, 2022

9:00–9:30 amBreakfast
9:30–11:00 amTalks
11:00–1:30 pmLunch break
1:30–4:00 pmDiscussions and Talks

August 5, 2022

9:00–9:30 amBreakfast
9:30–11:00 amTalks
11:00–1:30 pmLunch break
1:30–4:00 pmDiscussions and Talks

Anson Hook (UMD)Title: Early Universe Cosmology from Stochastic Gravitational Waves

Abstract:  The causal tail of stochastic gravitational waves can be used to probe the energy density in free streaming relativistic species as well as measure gstar and beta functions as a function of temperature. In the event of the discovery of loud stochastic gravitational waves, we demonstrate that LISA can measure the free streaming fraction of the universe down to the 10^-3 level, 100 times more sensitive than current constraints. Additionally, it would be sensitive to O(1) deviations of gstar and the QCD beta function from their Standard Model value at temperatures ~ 10^5 GeV. In this case, many motivated models such as split SUSY and other solutions to the Electroweak Hierarchy problem would be tested. Future detectors, such as DECIGO, would be 100 times more sensitive than LISA to these effects and be capable of testing other motivated scenarios such as WIMPs and axions. The amazing prospect of using precision gravitational wave measurements to test such well motivated theories provides a benchmark to aim for when developing a precise understanding of the gravitational wave spectrum both experimentally and theoretically.

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