# Ghazal Geshnizjani

University of Waterloo

Areas of research:

### Affiliations

Faculty at Department of Applied Mathematics, University of Waterloo \\
PSI fellow at Perimeter Institute

### Research Interests

My research has so far included tackling different aspects of theoretical cosmology such as investigating inflationary and bouncing scenarios, models of dark energy, modifications of general relativity, backreaction of metric perturbations, cosmic strings in extra dimensions and initial conditions for quantum fluctuations.
While mathematically intertwined, these research topics aim at understanding the theoretical puzzles about our cosmos in different phases of its evolution.

### Positions Held

- Women in Math Committee Chair, University of Waterloo
- Faculty at Waterloo Centre for Astrophysics, University of Waterloo
- Research Associate Professor, Department of Applied Mathematics, University of Waterloo

### Awards

- Dissertation Fellowship Award, Award, Brown University

### Recent Publications

- "Cuscuton bounce", S. S. Boruah, H. J. Kim, M. Rouben and G. Geshnizjani, arXiv: 1802.06818 [gr-qc], JCAP 1808, no. 08, 031 (2018)
- "Extended Effective Field Theory of Inflation", A. Ashoorioon, R. Casadio, M. Cicoli, G. Geshnizjani and H. J. Kim., arXiv: 1802.03040 [hep-th], JHEP 1802, 172 (2018)
- "Getting Super-Excited with Modified Dispersion Relations", A. Ashoorioon, R. Casadio, G. Geshnizjani and H. J. Kim., arXiv: 1702.06101 [hep-th], JCAP 1709, no. 09, 008 (2017)
- "Theory of Cosmological Perturbations with Cuscuton", S. S. Boruah, H. J. Kim and G. Geshnizjani., arXiv: 1704.01131 [hep-th], JCAP 0417, 022 (2017)
- "Theoretical implications of detecting gravitational waves", G. Geshnizjani and W. H. Kin- ney., arXiv: 1410.4968 [astro-ph.CO], JCAP 1508, no. 08, 008 (2015)
- "Can non-local or higher derivative theories provide alternatives to inflation?", G. Geshnizjani and N. Ahmadi., arXiv: 1309.4782 [hep-th], JCAP 1311, 029 (2013)
- "Eternal inflation and a thermodynamic treatment of Einstein"s equations", J. T. Galvez Ghersi, G. Geshnizjani, F. Piazza and S. Shandera., arXiv: 1103.0783 [gr-qc], JCAP 1106, 005 (2011)
- "General conditions for scale-invariant perturbations in an expanding universe", G. Gesh- nizjani, W. H. Kinney and A. M. Dizgah., arXiv: 1107.1241 [astro-ph.CO], JCAP 1111, 049 (2011)
- "The effect of extra dimensions on gravity wave bursts from cosmic string cusps", E. O"Callaghan, S. Chadburn, G. Geshnizjani, R. Gregory and I. Zavala., arXiv: 1005.3220 [hep-th], JCAP 1009, 013 (2010
- "Effect of Extra Dimensions on Gravitational Waves from Cosmic Strings", E. O"Callaghan, S. Chadburn, G. Geshnizjani, R. Gregory and I. Zavala., arXiv: 1003.4395 [hep-th], Phys. Rev. Lett. 105, 081602 (2010)
- Niayesh Afshordi, Ghazal Geshnizjani, Justin Khoury (Perimeter Institute), Observational Evidence for Cosmological-Scale Extra Dimensions, JCAP 08 (2009) 030, arXiv: 0812.2244
- "Reconstructing a general inflationary action", R. Bean, D. J. H. Chung and G. Geshnizjani., arXiv: 0801.0742 [astro-ph], Phys. Rev. D 78, 023517 (2008)
- Niayesh Afshordi (ITC, Harvard), Daniel J.H. Chung (UW-Madison), Michael Doran (Heidelberg), Ghazal Geshnizjani (UW-Madison), Cuscuton Cosmology: Dark Energy meets Modified Gravity, Phys.Rev.D75:123509,2007, arXiv: astro-ph/0702002
- Niayesh Afshordi (ITC, Harvard), Daniel J.H. Chung, Ghazal Geshnizjani (UW-Madison), Cuscuton: A Causal Field Theory with an Infinite Speed of Sound, Phys.Rev.D75:083513,2007, arXiv: hep-th/0609150
- Ghazal Geshnizjani, Thorsten J. Battefeld, A Note on Perturbations During a Regular Bounce, Phys.Rev. D73 (2006) 048501, arXiv: hep-th/0506139
- Ghazal Geshnizjani, Daniel J.H. Chung (UW-Madison), Niayesh Afshordi (Harvard), Do Large-Scale Inhomogeneities Explain Away Dark Energy?, Phys.Rev. D72 (2005) 023517, arXiv: astro-ph/0503553
- T. J. Battefeld, G. Geshnizjani, Perturbations in a regular bouncing Universe, Phys.Rev. D73 (2006) 064013, arXiv: hep-th/0503160
- Ghazal Geshnizjani, Niayesh Afshordi, Coarse-Grained Back Reaction in Single Scalar Field Driven Inflation, JCAP 0501 (2005) 011, arXiv: gr-qc/0405117
- Ghazal Geshnizjani, Robert Brandenberger, Back Reaction Of Perturbations In Two Scalar Field Inflationary Models, JCAP 0504 (2005) 006, arXiv: hep-th/0310265
- R. Brandenberger, G. Geshnizjani, S. Watson (Brown Univ.), On the Initial Conditions for Brane Inflation, Phys.Rev. D67 (2003) 123510, arXiv: hep-th/0302222
- Ghazal Geshnizjani, Robert Brandenberger, Back Reaction And Local Cosmological Expansion Rate, Phys.Rev.D66:123507,2002, arXiv: gr-qc/0204074

### Seminars

- Observational Evidence for Cosmological-Scale Extra Dimensions}, Theory Canada 5, University of New Brunswick, Fredericon, NB, Canada
- Observational Evidence for Cosmological-Scale Extra Dimensions},Program on Connecting Fundamental Physics with Observations, Kavli Institute for Theoretical Physics China at the Chinese Academy of Sciences (KITPC), Beijing, China
- Observational Evidence for Cosmological-Scale Extra Dimensions,Joint Seminars on Cosmology and Gravitation, The Institute for the Physics and Mathematics of the Universe (IPMU), Kashiwa city, Japan
- Explaining Anomalies in Cosmology with Modified Gravity, High Energy Theory Seminar, University of Michigan, Ann Arbor, MI
- Constraining the Inflationary Action with Cosmological Observations, Cosmology Seminar, Institut D'Astrophysique De Paris, Paris, France
- Cosmic Inflation through Time, Colloquium, Physics Department, University of Syracuse, Syracuse, NY
- Constraining the Inflationary Action with Cosmological Observations, High Energy Theory/ Relativity/ Cosmology Seminars, Physics Department, University of Syracuse, Syracuse, NY
- Cosmic Inflation through Time, Colloquium, Physics Department, York University, Toronto, Ontario, Canada
- Cosmic Inflation through Time, Colloquium, Physics Department, University of Utah, Salt Lake City, UT
- Investigating Reconstructing of a General, Slow-roll, Inflationary Action from CMB Observations, Cosmic Microwave Radiation Conference, Center for Physcis, Aspen, CO
- Cuscuton Cosmology: Dark Energy meets Modified Gravity}, High Energy Physics seminar, Physics Department, McGill University, Montreal, Canada
- PIRSA:09050084, Observational Evidence for Cosmological-Scale Extra Dimensions, 2009-05-26, New Prospects for Solving the Cosmological Constant Problem
- PIRSA:08060133, Constraining the inflationary action with cosmological observations, 2008-06-03, PASCOS 08
- Cuscuton Cosmology: Dark Energy meets Modied Gravity,2006-11-10, Cosmology on the Great Lakes Meeting