Physics Potential of a Radio Surface Array at the South Pole (ARENA 2018)

A surface array of radio antennas will enhance the performance of the IceTop array and enable new, complementary science goals. First, the accuracy for cosmic-ray air showers will be increased since the radio array provides a calorimetric measurement of the electromagnetic component and is sensitive to the position of the shower maximum. This enhanced accuracy can be used to better measure the mass composition, to search for possible mass-dependent anisotropies in the arrival directions of cosmic rays, and for more thorough tests of hadronic interaction models. Second, the sensitivity of the radio array to inclined showers will increase the sky coverage for cosmic-ray measurements. Third, the radio array can be used to search for PeV photons from the Galactic Center. Since IceTop is planned to be enhanced by a scintillator array in the near future, a radio extension sharing the same infrastructure can be installed with minimal additional effort and excellent scientific prospects. The combination of ice-Cherenkov, scintillation, and radio detectors at IceCube will provide unprecedented accuracy for the study of highenergy Galactic cosmic rays.Comment: Proceedings of 8th ARENA 2018, to appear in EPJ Wo

Retardation of Particle Evaporation from Excited Nuclear Systems Due to Thermal Expansion

Particle evaporation rates from excited nuclear systems at equilibrium matter density are studied within the Harmonic-Interaction Fermi Gas Model (HIFGM) combined with Weisskopf's detailed balance approach. It is found that thermal expansion of a hot nucleus, as described quantitatively by HIFGM, leads to a significant retardation of particle emission, greatly extending the validity of Weisskopf's approach. The decay of such highly excited nuclei is strongly influenced by surface instabilities

Fixed Export Cost heterogeneity, Trade and Welfare

Recent literature on the workhorse model of intra-industry trade has explored heterogeneous cost structures at the firm level. These approaches have proven to add realism and predictive power. This paper presents a new and simple heterogeneous-firms specification. We develop a symmetric two-country intra-industry trade model where firms are of two different marginal costs types and where fixed export costs are heterogeneous across firms. This model traces many of the stylized facts of international trade. However, we find that with heterogeneous fixed export costs there exists a positive bilateral tariff that maximizes national and world welfare.Intra-industry trade, trade liberalization, monopolistic competition, heterogeneous firms,welfare, protectionism

Reductions in Real versus Tariff Barriers: The Effects on Industry Concentration

Economic integration in Europe has had ambiguous effects on industry concentration. The literature has proposed various explanations of the empirical findings. The present paper provides an additional theoretical argument. We show that in a world of monopolistic competition, integration in it self (modelled as a reduction of trade barriers) generates opposing effects on industry concentration, depending on wether the barrier is a real (frictional) or a tariff cost. In particular, the Herfindahl index of industry concentration falls for a reduction in real costs, but rises for a reduction in tariff costs. The reason is that real barriers burn up resources, such that industry profitability is reduced, reducing entry, and resulting in fewer firms and higher concentration. Under a tariff barrier, the redistributed tariff revenue stabilises industry profitability, resulting in more firms and lower concentration.real costs; tariff costs; industry concentration; market structure; integration

Enhancing the cosmic-ray mass sensitivity of air-shower arrays by combining radio and muon detectors

The muonic and electromagnetic components of air showers are sensitive to the mass of the primary cosmic particle. The sizes of the components can be measured with particle detectors on ground, and the electromagnetic component in addition indirectly via its radio emission in the atmosphere. The electromagnetic particles do not reach the ground for very inclined showers. On the contrary, the atmosphere is transparent for the radio emission and its footprint on ground increases with the zenith angle. Therefore, the radio technique offers a reliable detection over the full range of zenith angles, and in particular for inclined showers. In this work, the mass sensitivity of a combination of the radio emission with the muons is investigated in a case study for the site of the Pierre Auger Observatory using CORSIKA Monte Carlo simulations of showers in the EeV energy range. It is shown, that the radio-muon combination features superior mass separation power in particular for inclined showers, when compared to established mass observables such as a combination of muons and electrons or the shower maximum Xmax. Accurate measurements of the energy-dependent mass composition of ultra-high energy cosmic rays are essential to understand their still unknown origin. Thus, the combination of muon and radio detectors can enhance the scientific performance of future air-shower arrays and offers a promising upgrade option for existing arrays

O⋆O^\star-algebras and quantum dynamics: some existence results

We discuss the possibility of defining an algebraic dynamics within the settings of $O^\star$-algebras. Compared with our previous results on this subject, the main improvement here is that we are not assuming the existence of some hamiltonian for the {\em full} physical system. We will show that, under suitable conditions, the dynamics can still be defined via some limiting procedure starting from a given {\em regularized sequence}