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Linear groups and computation (2018)
Journal Article
Detinko, A. S., & Flannery, D. L. (2019). Linear groups and computation. Expositiones Mathematicae, 37(4), 454-484. https://doi.org/10.1016/j.exmath.2018.07.002

We present an exposition of our ongoing project in a new area of applicable mathematics: practical computation with finitely generated linear groups over infinite fields. Methodology and algorithms available for this class of groups are surveyed. We... Read More about Linear groups and computation.

Primordial Gravitational Waves and Reheating in a New Class of Plateau-Like Inflationary Potentials (2018)
Journal Article
Chongchitnan, S. (2018). Primordial Gravitational Waves and Reheating in a New Class of Plateau-Like Inflationary Potentials. Universe, 4(7), Article 77. https://doi.org/10.3390/universe4070077

We study a new class of inflation model parametrized by the Hubble radius, such that aH∝exp(−αφ)n. These potentials are plateau-like, and reduce to the power-law potentials in the simplest case n=2. We investigate the range of model parameters that i... Read More about Primordial Gravitational Waves and Reheating in a New Class of Plateau-Like Inflationary Potentials.

Large deviations for the annealed Ising model on inhomogeneous random graphs: spins and degrees (2018)
Journal Article
Dommers, S., Giardinà, C., Giberti, C., & Hofstad, R. V. D. (2018). Large deviations for the annealed Ising model on inhomogeneous random graphs: spins and degrees. Journal of statistical physics, 173(3-4), 1045-1081. https://doi.org/10.1007/s10955-018-2027-8

We prove a large deviations principle for the total spin and the number of edges under the annealed Ising measure on generalized random graphs. We also give detailed results on how the annealing over the Ising model changes the degrees of the vertice... Read More about Large deviations for the annealed Ising model on inhomogeneous random graphs: spins and degrees.

Zariski density and computing in arithmetic groups (2017)
Journal Article
Detinko, A., Flannery, D. L., & Hulpke, A. (2018). Zariski density and computing in arithmetic groups. Mathematics of Computation, 87(310), 967-986. https://doi.org/10.1090/mcom/3236

For n > 2, let Gamma _n denote either SL(n, {Z}) or Sp(n, {Z}). We give a practical algorithm to compute the level of the maximal principal congruence subgroup in an arithmetic group H\leq \Gamma _n. This forms the main component of our methods for c... Read More about Zariski density and computing in arithmetic groups.

Orbits of primitive k-homogenous groups on (N − k)-partitions with applications to semigroups (2017)
Journal Article
Araújo, J., Bentz, W., & Cameron, P. J. (2018). Orbits of primitive k-homogenous groups on (N − k)-partitions with applications to semigroups. Transactions of the American Mathematical Society, 371(1), 105-136. https://doi.org/10.1090/tran/7274

© 2018 American Mathematical Society. The purpose of this paper is to advance our knowledge of two of the most classic and popular topics in transformation semigroups: automorphisms and the size of minimal generating sets. In order to do this, we exa... Read More about Orbits of primitive k-homogenous groups on (N − k)-partitions with applications to semigroups.

Inflation model building with an accurate measure of e-folding (2016)
Journal Article
Chongchitnan, S. (2016). Inflation model building with an accurate measure of e-folding. Physical Review D, 94(4), Article 043526. https://doi.org/10.1103/PhysRevD.94.043526

It has become standard practice to take the logarithmic growth of the scale factor as a measure of the amount of inflation, despite the well-known fact that this is only an approximation for the true amount of inflation required to solve the horizon... Read More about Inflation model building with an accurate measure of e-folding.

Ambitwistor string theory in the operator formalism (2016)
Journal Article
Reid-Edwards, R. A. (2016). Ambitwistor string theory in the operator formalism. Journal of High Energy Physics, 2016(6), 84-1-84-31. https://doi.org/10.1007/jhep06%282016%29084

© 2016, The Author(s). Abstract: After a brief overview of the operator formalism for conventional string theory, an operator formalism for ambitwistor string theory is presented. It is shown how tree level supergravity scattering amplitudes are reco... Read More about Ambitwistor string theory in the operator formalism.

Metastability of the Ising model on random regular graphs at zero temperature (2015)
Journal Article
Dommers, S. (2017). Metastability of the Ising model on random regular graphs at zero temperature. Probability theory and related fields, 167(1-2), 305-324. https://doi.org/10.1007/s00440-015-0682-0

We study the metastability of the ferromagnetic Ising model on a random r-regular graph in the zero temperature limit. We prove that in the presence of a small positive external field the time that it takes to go from the all minus state to the all p... Read More about Metastability of the Ising model on random regular graphs at zero temperature.

On the abundance of extreme voids (2015)
Journal Article
Chongchitnan, S. (2015). On the abundance of extreme voids. Journal of cosmology and astroparticle physics, May(05), 062-062. https://doi.org/10.1088/1475-7516/2015/05/062

Cosmic voids have been shown to be an effective probe of cosmology, complementary to galaxy clusters. In this work, we present a simple theoretical framework for predicting of the size of the largest voids expected within a given redshift and volume.... Read More about On the abundance of extreme voids.

The Lyman α forest as a tool for disentangling non-Gaussianities (2014)
Journal Article
Chongchitnan, S. (2014). The Lyman α forest as a tool for disentangling non-Gaussianities. Journal of cosmology and astroparticle physics, 2014(10), Article ARTN 034. https://doi.org/10.1088/1475-7516/2014/10/034

© 2014 IOP Publishing Ltd and Sissa Medialab srl . Detection of primordial non-Gaussianity will give us an unprecedented detail of the physics of inflation. As observational probes are now exploring new expanses of the inflationary landscape, it is c... Read More about The Lyman α forest as a tool for disentangling non-Gaussianities.

Lattice gerbe theory (2014)
Journal Article
Lipstein, A. E., & Reid-Edwards, R. A. (2014). Lattice gerbe theory. Journal of High Energy Physics, 2014(9), Article ARTN 034. https://doi.org/10.1007/JHEP09%282014%29034

We formulate the theory of a 2-form gauge field on a Euclidean spacetime lattice. In this approach, the fundamental degrees of freedom live on the faces of the lattice, and the action can be constructed from the sum over Wilson surfaces associated wi... Read More about Lattice gerbe theory.

Constraining isocurvature perturbations with the 21 cm emission from minihaloes (2014)
Journal Article
Takeuchi, Y., & Chongchitnan, S. (2014). Constraining isocurvature perturbations with the 21 cm emission from minihaloes. Monthly notices of the Royal Astronomical Society, 439(1), 1125-1135. https://doi.org/10.1093/mnras/stu059

We investigate the effects of isocurvature perturbations on the 21 cm radiation from minihaloes (MHs) at high redshifts and examine constraints on the isocurvature amplitude and power spectrum using the next generation of radio telescopes such as the... Read More about Constraining isocurvature perturbations with the 21 cm emission from minihaloes.

The effect of cosmic magnetic fields on the metagalactic ionization background inferred from the Lyman α forest (2013)
Journal Article
Chongchitnan, S., & Meiksin, A. (2014). The effect of cosmic magnetic fields on the metagalactic ionization background inferred from the Lyman α forest. Monthly notices of the Royal Astronomical Society, 437(4), 3639-3646. https://doi.org/10.1093/mnras/stt2169

The sources which reionized the intergalactic medium by redshift ̃6 are still unknown. A severe constraint on the ionization process is the low emissivity required to maintain the ionization in the Lya forest. Simulation-calibrated observations sugge... Read More about The effect of cosmic magnetic fields on the metagalactic ionization background inferred from the Lyman α forest.