Kim Jong-un’s tools of coercion. IES Policy Brief No. 6, June 2018

Last fall and winter, the world was tense with the real possibilities of a military conflict breaking out on the Korean Peninsula as a result of Kim Jongun’s testing of intercontinental ballistic missiles, the North’s sixth and largest nuclear test, and the rhetorical war with U.S. President Donald Trump. While the threat of another Korean war seems to be in the rear-view mirror, for now, we have to remember that Kim has been expanding, sharpening, and demonstrating other tools of coercive diplomacy, including selective engagement, cyberattacks, and chemical weapons. He has been deploying these tools to suppress criticism of the regime, sow division within South Korea and among U.S. allies and regional stakeholders, and shape an external environment favorable for reinforcing Kim’s legitimacy and North Korea’s claimed status as a nuclear weapons power

Muon anomaly and a lower bound on higgs mass due to a light stabilized radion in the Randall-Sundrum model

We investigate the Randall-Sundrum model with a light stabilized radion (required to fix the size of the extra dimension) in the light of muon anomalous magnetic moment $a_\mu [= \frac{(g - 2)}{2}]$. Using the recent data (obtained from the E821 experiment of the BNL collaboration) which differs by $2.6 \sigma$ from the Standard Model result, we obtain constraints on radion mass \mphi and radion vev \vphi. In the presence of a radion the beta functions \beta(\l) and $\beta(g_t)$ of higgs quartic coupling (\l) and top-Yukawa coupling ($g_t$) gets modified. We find these modified beta functions. Using these beta functions together with the anomaly constrained \mphi and \vphi, we obtain lower bound on higgs mass $m_h$. We compare our result with the present LEP2 bound on $m_h$.Comment: Version to be appeared in IJMP

Lyapunov exponent and natural invariant density determination of chaotic maps: An iterative maximum entropy ansatz

We apply the maximum entropy principle to construct the natural invariant density and Lyapunov exponent of one-dimensional chaotic maps. Using a novel function reconstruction technique that is based on the solution of Hausdorff moment problem via maximizing Shannon entropy, we estimate the invariant density and the Lyapunov exponent of nonlinear maps in one-dimension from a knowledge of finite number of moments. The accuracy and the stability of the algorithm are illustrated by comparing our results to a number of nonlinear maps for which the exact analytical results are available. Furthermore, we also consider a very complex example for which no exact analytical result for invariant density is available. A comparison of our results to those available in the literature is also discussed.Comment: 16 pages including 6 figure

General Neutralino NLSPs at the Early LHC

Gauge mediated supersymmetry breaking (GMSB) is a theoretically well-motivated framework with rich and varied collider phenomenology. In this paper, we study the Tevatron limits and LHC discovery potential for a wide class of GMSB scenarios in which the next-to-lightest superpartner (NLSP) is a promptly-decaying neutralino. These scenarios give rise to signatures involving hard photons, $W$'s, $Z$'s, jets and/or higgses, plus missing energy. In order to characterize these signatures, we define a small number of minimal spectra, in the context of General Gauge Mediation, which are parameterized by the mass of the NLSP and the gluino. Using these minimal spectra, we determine the most promising discovery channels for general neutralino NLSPs. We find that the 2010 dataset can already cover new ground with strong production for all NLSP types. With the upcoming 2011-2012 dataset, we find that the LHC will also have sensitivity to direct electroweak production of neutralino NLSPs.Comment: 26 page

On the interaction of a thin, supersonic shell with a molecular cloud

Molecular clouds (MCs) are stellar nurseries, however, formation of stars within MCs depends on the ambient physical conditions. MCs, over a free-fall time are exposed to numerous dynamical phenomena, of which, the interaction with a thin, dense shell of gas is but one. Below we present results from self-gravitating, 3-D smoothed particle hydrodynamics ({\small SPH}) simulations of the problem; seven realisations of the problem have been performed by varying the precollision density within the cloud, the nature of the post-collision shock, and the spatial resolution in the computational domain. Irrespective of the type of shock, a complex network of dense filaments, seeded by numerical noise, readily appears in the shocked cloud. Segregation of the dense and rarefied gas phases also manifests itself in a bimodal distribution of gas density. We demonstrate that the power-spectrum for rarefied gas is Kolomogorov like, while that for the denser gas is considerably steeper. As a corollary to the main problem, we also look into the possibly degenerative effect of the {\small SPH} artificial viscosity on the impact of the incident shell. It is observed that stronger viscosity leads to greater post-shock dissipation, that strongly decelerates the incident shock-front and promotes formation of contiguous structure, albeit on a much longer timescale. We conclude that too much viscosity is likely to enhance the proclivity towards gravitational boundedness of structure, leading to unphysical fragmentation.On the other hand, insufficient resolution appears to suppress fragmentation. Convergence of results is tested at both extremes, first by repeating the test case with more than a million particles and then with only half the number of particles in the original test case.Comment: 15 pages, 15 figures, and 1 Table; To appear in Monthly Notices to the RA