On the Emergence and Evolution of Mark-up Middlemen: An Inframarginal Model

This paper is aimed to provide an economic interpretation on the emergence and evolution of the specialised middlemen whose duty is to facilitate the transactions of goods and services in an economy. In a general equilibrium framework, the emergence and evolution of the specialised middlemen conforms to Adam Smith’s insight of deepening specialisation and the division of labour with the improvement in institutions and/or transaction technologies. Consequently, the emergence and the growth of the intermediation sector in both absolute and relative terms, the expansion of the network which provides transaction services, the evolution of market structure from autarky towards division of labour, the improvement in productivity, the reduction in wholesaling-retailing price dispersion, will be realised in concurrencymiddlemen, transaction efficiency, inframarginal economics

Searching for Heavier Higgs Boson via Di-Higgs Production at LHC Run-2

The LHC discovery of a light Higgs particle $h^0$ (125GeV) opens up new prospect for searching heavier Higgs boson(s) at the LHC Run-2, which will unambiguously point to new physics beyond the standard model (SM). We study the detection of a heavier neutral Higgs boson $H^0$ via di-Higgs production channel at the LHC (14TeV), $H^0 \to h^0h^0 \to WW^*\gamma\gamma$. This directly probes the $Hhh$ cubic Higgs interaction, which exists in most extensions of the SM Higgs sector. For the decay products of final states $WW^*$, we include both pure leptonic mode $WW^* \to \ell\bar{\nu}\bar{\ell}\nu$ and semi-leptonic mode $WW^* \to q\bar{q}'\ell\nu$. We analyze signals and backgrounds by performing fast detector simulation for the full processes $pp \to H \to hh \to WW^*\gamma\gamma \to \ell\bar{\nu}\bar{\ell}\nu\gamma\gamma$ and $pp \to H \to hh \to WW^*\gamma\gamma \to \ell\nu q\bar{q}'\gamma\gamma$, over the mass range $M_H=250-600$GeV. For generic two-Higgs-doublet models (2HDM), we present the discovery reach of the heavier Higgs boson at the LHC Run-2, and compare it with the current Higgs global fit of the 2HDM parameter space.Comment: Phys.Lett.B Final Version. 16pp (9 Figs + 4 Tables). Only minor refinements, references adde

Theories of Linear Response in BCS Superfluids and How They Meet Fundamental Constraints

We address the importance of symmetry and symmetry breaking on linear response theories of fermionic BCS superfluids. The linear theory of a noninteracting Fermi gas is reviewed and several consistency constraints are verified. The challenge to formulate linear response theories of BCS superfluids consistent with density and spin conservation laws comes from the presence of a broken U(1)$_{\textrm{EM}}$ symmetry associated with electromagnetism (EM) and we discuss two routes for circumventing this. The first route follows Nambu's integral-equation approach for the EM vertex function, but this method is not specific for BCS superfluids. We focus on the second route based on a consistent-fluctuation-of-the order-parameter (CFOP) approach where the gauge transformation and the fluctuations of the order parameter are treated on equal footing. The CFOP approach allows one to explicitly verify several important constraints: The EM vertex satisfies not only a Ward identity which guarantees charge conservation but also a $Q$-limit Ward identity associated with the compressibility sum rule. In contrast, the spin degrees of freedom associated with another U(1)$_z$ symmetry are not affected by the Cooper-pair condensation that breaks only the U(1)$_{\textrm{EM}}$ symmetry. As a consequence the collective modes from the fluctuations of the order parameter only couple to the density response function but decouple from the spin response function, which reflects the different fates of the two U(1) symmetries in the superfluid phase. Our formulation lays the ground work for application to more general theories of BCS-Bose Einstein Condensation crossover both above and below $T_c$.Comment: Review on gauge invariance and charge-spin difference of BCS theory. 27 pages, 1 figure. Some typos have been correcte