Naturalness and Dark Matter Properties of the BLSSM

In this report, we compare the naturalness and Dark Matter (DM) properties of the Minimal Supersymmetric Standard Model (MSSM) and the $B-L$ Supersymmetric Standard Model (BLSSM), with universality in both cases. We do this by adopting standard measures for the quantitative analysis of the Fine-Tuning (FT), at both low (i.e. supersymmetric (SUSY)) and high (i.e. unification) scales. We will see a similar level of FT for both models in these scenarios, with a slightly better FT for the BLSSM at SUSY scales and MSSM at Grand Unification Theory (GUT) scales. When including DM relic constraints, we drastically confine the MSSM's parameter space, whereas we still find a large parameter space available for the non-minimal scenario.Comment: Prepared for proceedings for DIS2017, talk presented by Simon Kin

Simulation-based inference using surjective sequential neural likelihood estimation

We present Surjective Sequential Neural Likelihood (SSNL) estimation, a novel method for simulation-based inference in models where the evaluation of the likelihood function is not tractable and only a simulator that can generate synthetic data is available. SSNL fits a dimensionality-reducing surjective normalizing flow model and uses it as a surrogate likelihood function which allows for conventional Bayesian inference using either Markov chain Monte Carlo methods or variational inference. By embedding the data in a low-dimensional space, SSNL solves several issues previous likelihood-based methods had when applied to high-dimensional data sets that, for instance, contain non-informative data dimensions or lie along a lower-dimensional manifold. We evaluate SSNL on a wide variety of experiments and show that it generally outperforms contemporary methods used in simulation-based inference, for instance, on a challenging real-world example from astrophysics which models the magnetic field strength of the sun using a solar dynamo model

Social Democracy and Distributive Conflict in the UK, 1950- 2010

In the last three decades, two questions have been central for the Left. Is there a future for electoral socialism and social democracy? And, is it any longer possible to promote a significant redistribution of income in favour of labour? Political and economic events seem to suggest negative answers. In his influential work, Adam Przeworski suggests that this is an irreversible trend that makes it impossible in the long-run to promote genuinely socialist objectives in capitalist democracies. In particular, the structural dependence of labour on capital severely constrains feasible income distributions. In this paper, a detailed quantitative and qualitative analysis of the post-war UK economy is provided which casts doubts on the structural dependence thesis. A short run pro.t-squeeze mechanism seems to exist, but income shares are more variable than the structural dependence argument suggests, and the power resources available to the two main classes in the economy are among the key determinants of distributive outcomes, different political-economic equilibria corresponding to different configurations of the balance of power between the two classes

The limitations of the structural dependence thesis: class, power, and distributive conflict in the UK since 1892

Can political parties, social movements, and governments shape the functioning of a capitalist economy? Is it possible for social democratic parties to promote a significant redistribution of income in favour of labour? According to proponents of the structural dependence thesis, the answer is negative, because the structural dependence of labour upon capital severely constrains feasible income distributions. Carlo V. Fiorio, Simon Mohun, and Roberto Veneziani cast doubts on this thesis. Their historical analysis of the UK finds some evidence of a short-run profit-squeeze mechanism, but also that income shares are much more variable than the structural dependence argument suggests, and the power resources available to social classes are among the key determinants of distributive outcomes

Prospects for Sneutrino Dark Matter in the BLSSM

The $(B-L)$ Supersymmetric Standard Model (BLSSM) motivates several Dark Matter (DM) candidates beyond the Minimally Supersymmetric Standard Model (MSSM). We assess the comparative naturalness of the two models and discuss the potential detection properties of a particular candidate, the Right-Handed (RH) sneutrino.Comment: Prepared for proceedings for La Thuile 2018, talk by Simon Kin

Sneutrino Dark Matter in the BLSSM

In the framework of the $(B-L)$ Supersymmetric Standard Model (BLSSM), we assess the ability of ground and space based experiments to establish the nature of its prevalent Dark Matter (DM) candidate, the sneutrino, which could either be CP-even or -odd. Firstly, by benchmarking this theory construct against the results obtained by the Planck spacecraft, we extract the portions of the BLSSM parameter space compliant with relic density data. Secondly, we show that, based on current sensitivities of the Fermi Large Area Telescope (FermiLAT) and their future projections, the study of high-energy $\gamma$-ray spectra will eventually enable us to extract evidence of this DM candidate through its annihilations into $W^+W^-$ pairs (in turn emitting photons), in the form of both an integrated flux and a differential energy spectrum which cannot be reconciled with the assumption of DM being fermionic (like, e.g., a neutralino), although it should not be possible to distinguish between the scalar and pseudoscalar hypotheses. Thirdly, we show that, while underground direct detection experiments will have little scope in testing sneutrino DM, the Large Hadron Collider (LHC) may be able to do so in a variety of multi-lepton signatures, with and without accompanying jets (plus missing transverse energy), following data collection during Run 2 and 3.Comment: 16 pages, 8 figure