Emission Tax or Standard? The Role of Productivity Dispersion

When a society wants to control aggregate emission under a certain target level, is it more desirable to impose a tax or a regulatory standard on emission? To answer this question, we explore a model where plants are heterogeneous in productivity and monopolistically competitive in the production of a set of varieties of (dirty-) goods whose by-product is emission. The main result is that the standard yields higher welfare than the tax if and only if productivity dispersion is small and the monopoly power in the dirty-goods sector is strong. In the process of obtaining this result, we find that, if the plants have no access to an abatement technology, then the tax dominates the standard unambiguously. When the plants do have access to an abatement technology, there can be less price distortion under the standard than under the tax, in which case the standard can yield higher welfare. These results illustrate that productivity dispersion is important for evaluating market-based environmental policies relative to non-market based policies.emission tax; standard; productivity dispersion;abatement.

Fermion Pairing across a Dipolar Interaction Induced Resonance

It is known from the solution of the two-body problem that an anisotropic dipolar interaction can give rise to s-wave scattering resonances, which are named as dipolar interaction induced resonaces (DIIR). In this letter, we study zero-temperature many-body physics of a two-component Fermi gas across a DIIR. In the low-density regime, it is very striking that the resulting pairing order parameter is a nearly isotropic singlet pairing and the physics can be well described by an s-wave resonant interaction potential with finite range corrections, despite of the anisotropic nature of dipolar interaction. The pairing energy is as strong as a unitary Fermi gas nearby a magnetic Feshbach resonance. In the high density regime, the anisotropic effect plays an important role. We find phase transitions from singlet pairing to a state with mixed singlet and triplet pairing, and then from mixed pairing to pure triplet pairing. The state with mixed pairing spontaneously breaks the time-reversal symmetry.Comment: 4.5 pages, 4 figures, figures updated, minor changes in tex

s-Wave Scattering Resonances Induced by Dipolar Interactions of Polar Molecules

We show that s-wave scattering resonances induced by dipolar interactions in a polar molecular gas have a universal large and positive effective range, which is very different from Feshbach resonances realized in cold atoms before, where the effective range is either negligible or negative. Such a difference has important consequence in many-body physics. At high temperature regime, a positive effective range gives rise to stronger repulsive interaction energy for positive scattering length, and weaker attractive interaction energy for negative scattering length. While at low-temperatures, we study polaron problem formed by single impurity molecule, and we find that the polaron binding energy increases at the BEC side and decreases at the BCS side. All these effects are in opposite to narrow Feshbach resonances where the effective range is negative.Comment: 5 pages, 3 figures, published versio

Implement Artificial Reverberation by using filterbank methods

Contains fulltext : 148832.pdf (publisher's version ) (Open Access)Radboud Universiteit Nijmegen, 04 november 2015Promotores : Lamers, L.P.M., Roelofs, J.G.M. Co-promotor : Smolders, A.J.P.139 p

Viscous effects on the dynamical evolution of QCD matter during the first-order confinement phase transition in heavy-ion collisions

We investigate viscous effects on the dynamical evolution of QCD matter during the first-order phase transition, which may happen in heavy-ion collisions. We first obtain the first-order phase transition line in the QCD phase diagram under the Gibbs condition by using the MIT bag model and the hadron resonance gas model for the equation of state of partons and hadrons. The viscous pressure, which corresponds to the friction in the energy balance, is then derived from the energy and net baryon number conservation during the phase transition. We find that the viscous pressure relates to the thermodynamic change of the two-phase state and thus affects the timescale of the phase transition. Numerical results are presented for demonstrations.Comment: 7 pages, 5 figures; title, some text and Figs. 1 and 2 are modified, typos fixed; published versio