Pavel Fileviez Perez, Axel Gross, Clara Murgui

We investigate a simple realistic grand unified theory based on the $SU(5)$ gauge symmetry which predicts an upper bound on the proton decay lifetime for the channels $p \to K^+ \bar{\nu}$ and $p \to \pi^+ \bar{\nu}$, i.e. $\tau (p \to K^+ \bar{\nu}) \lesssim 3.4 \times 10^{35}$ and $\tau (p \to \pi^+ \bar{\nu}) \lesssim 1.7 \times 10^{34}$ years, respectively. In this context, the neutrino masses are generated through the type I and type III seesaw mechanisms, and one predicts that the field responsible for type III seesaw must be light with a mass below 500 TeV. We discuss the testability of this theory at current and future proton decay experiments.

Saurabh Kumar, Emanuela Dimastrogiovanni, Glenn D. Starkman, Craig Copi, Bryan Lynn

We propose a new mechanism by which dark matter (DM) can affect the early universe. The hot interior of a macroscopic DM, or macro, can behave as a heat reservoir so that energetic photons are emitted from its surface. This results in spectral distortions (SDs) of the cosmic microwave background. The SDs depend on the density and the cooling processes of the interior, and the surface composition of the Macros. We use neutron stars as a model for nuclear-density Macros and find that the spectral distortions are mass-independent for fixed density. In our work, we find that, for Macros of this type that constitute 100$\%$ of the dark matter, the $\mu$ and $y$ distortions can be above detection threshold for typical proposed next-generation experiments such as PIXIE.

K. Lawson, A.R. Zhitnitsky

We argue that dark matter in the form of macroscopically large nuggets of standard model quarks and antiquarks can help to alleviate the tension between standard model cosmology and the recent EDGES observation of a stronger than anticipated 21 cm absorption feature. The effect occurs as a result of the thermal emission from quark nugget dark matter at early times and at energies well below the peak of the CMB. Similar radiation at early times may also contribute a fraction of the GHz range excess observed by ARCADE2.

Eric Gourgoulhon, Marco Mancini

These lecture notes present a method for symbolic tensor calculus that (i) runs on fully specified smooth manifolds (described by an atlas), (ii) is not limited to a single coordinate chart or vector frame, (iii) runs even on non-parallelizable manifolds and (iv) is independent of the symbolic engine employed to perform calculus at the level of coordinate expressions. In addition to the main ideas, we discuss some details of the implementation in in the open-source mathematics software system SageMath, which has been performed via the SageManifolds project.

Yong Cai, Rehan Deen, Burt A. Ovrut, Austin Purves

The theory of reheating in the Sneutrino-Higgs cosmology of the $B-L$ MSSM is presented. It is shown that following an epoch of inflation consistent with all Planck2015 data, the inflaton begins to oscillate around its minimum at zero and to reheat to various species of standard model and supersymmetric matter. The decay rates to this matter are computed, both analytically and numerically. Using these results, the Hubble parameter and the relative energy densities for each matter species, including that of the inflaton, are calculated numerically. The inflaton energy density is demonstrated to vanish at an energy scale of ${\cal{O}}(10^{13})~{\rm GeV}$, signaling the end of the period of reheating. The newly created matter background is shown to be in thermal equilibrium, with a reheating temperature of $\simeq 1.13 \times 10^{13}~{\rm GeV}$. To allow for a $B-L$ breaking scale sufficiently smaller than the reheating scale, we extend the statistical method of determining the soft supersymmetry breaking parameters developed in previous work. The result is that one can determine a large number of phenomenologically realistic initial conditions for which the $B-L$ breaking scale is an order of magnitude or more smaller than the reheating scale.

Will Handley, Marius Millea

We propose a method for transforming probability distributions so that parameters of interest are forced into a specified distribution. We prove that this approach is the maximum entropy choice, and provide a motivating example applicable to neutrino hierarchy inference.

Marius Millea, François Bouchet

Non-parametric reconstruction or marginalization over the history of reionization using cosmic microwave background data necessarily assumes a prior over possible histories. We show that different but reasonable choices of priors can shift current and future constraints on the reionization optical depth, $\tau$, or correlated parameters such as the neutrino mass sum, $\Sigma m_\nu$, at the level of 0.3-0.4$\sigma$, i.e., that this analysis is somewhat prior dependent. We point out some prior-related problems with the commonly used principal component reconstruction, concluding that the significance of some recent hints of early reionization in Planck 2015 data has been overestimated. We also present the first non-parametric reconstruction applied to newer Planck intermediate (2016) data and find that the hints of early reionization disappear entirely in this more precise dataset. These results limit possible explanations of the EDGES 21cm signal which would have also significantly reionized the universe at $z\,{>}\,15$. Our findings about the dependence on priors motivate the pursuit of improved data or searches for physical reionization models which can reduce the prior volume. The discussion here of priors is of general applicability to other non-parametric reconstructions, for example of the primordial power spectrum, of the recombination history, or of the expansion rate.