Narrow Results

The global multiplicative properties of Laplace type operators acting on irreducible rank one symmetric spaces are considered. The explicit form of the multiplicative anomaly is derived and its corresponding value is calculated exactly, for important classes of locally symmetric spaces and different dimensions.

The presentation summarizes the excellent experimental conditions for tau physics at a tau-charm factory. A rough overview of the physics potential is given.

In this work, we study a warped five-dimensional (5D) model with ultraviolet (UV) and infrared (IR) branes, that solves the hierarchy problem with a fundamental 5D Planck scale $M$, and curvature parameter $k$, of the order of the 4D Planck mass $M_{\mathrm{\text{Pl}}}\equiv 2.4\times 10^{15}$ TeV. The model exhibits a continuum of Kaluza–Klein (KK) modes with different mass gaps, at the TeV scale, for all fields. We have computed Green’s functions and spectral densities, and shown how the presence of a continuum KK spectrum can produce an enhancement in the cross-section of some Standard Model processes. The metric is linear near the IR, in conformal coordinates, as in the linear dilaton (LD) and 5D clockwork models, for which $M\sim$ TeV. We also analyze a pure (continuum) LD scenario, solving the hierarchy problem with more conventional fundamental $M$ and $k$ scales of the order of $M_{\mathrm{\text{Pl}}}$, and a continuum spectrum.

The single-particle spectral functions in asymmetric nuclear matter are computed using the ladder approximation within the theory of finite temperature Green's functions. The internal energy and the momentum distributions of protons and neutrons are studied as a function of the density and the asymmetry of the system. The proton states are more strongly depleted when the asymmetry increases, whereas the occupation of the neutron states is enhanced compared to the symmetric case. Preliminary results for the entropy and the free energy are also presented.

Increasing experimental evidence points towards a two-fluid model for the low-temperature behavior of 5f systems. Assuming some 5f electrons to be localized atomic-like and others to be band-like itinerant can explain various unusual low-energy properties of U compounds including the formation of heavy fermion and their unconventional superconductivity. The dual model, however, provides an effective Hamiltonian which is valid only for the low-energy regime. It has been shown that intra-atomic correlations among the 5f electrons are a possible mechanism for orbital-selective (partial) localization. In this paper we theoretically derive criteria and specify properties which experimentally characterize correlation-induced partial localization in actinide compounds. Of particular interest are the 5f spectral function which can be related to photoemission data. Results for the U-based heavy fermion superconductor UPd₂Al₃ are presented emphasizing the consequences for the interpretation of experimental data.

The equation for the electron Green's function of the fermionic Hubbard model, derived using the strong coupling diagram technique, is solved self-consistently for the near-neighbor form of the kinetic energy and for half-filling. In this case the Mott transition occurs at the Hubbard repulsion U_c ≈ 6.96t, where t is the hopping constant. The calculated spectral functions, density of states (DOS) and momentum distribution are compared with results of Monte Carlo simulations. A satisfactory agreement was found for U > U_c and for temperatures, at which magnetic ordering and spin correlations are suppressed. For U < U_c and lower temperatures the theory describes qualitatively correctly the positions and widths of spectral continua, variations of spectral shapes and occupation numbers with changing wave vector and repulsion. The locations of spectral maxima turn out to be close to the positions of δ-function peaks in the Hubbard-I approximation.

The in-medium modifications of hadron properties such as masses and decay widths have been a major focus of the scientific work of Gerry Brown and the insights gained by him and his collaborators made them major drivers of this field for several decades. Their prediction of experimental signals in di-lepton pair production in relativistic heavy-ion collisions was instrumental in initiating large experimental campaigns which continue till today. In this chapter, we review recent results which elucidate the relation of hadronic spectral properties at finite temperature and density to the restoration of spontaneously broken chiral symmetry.

Increasing experimental evidence points towards a two-fluid model for the low-temperature behavior of 5f systems. Assuming some 5f electrons to be localized atomic-like and others to be band-like itinerant can explain various unusual low-energy properties of U compounds including the formation of heavy fermion and their unconventional superconductivity. The dual model, however, provides an effective Hamiltonian which is valid only for the low-energy regime. It has been shown that intra-atomic correlations among the 5f electrons are a possible mechanism for orbital-selective (partial) localization. In this paper we theoretically derive criteria and specify properties which experimentally characterize correlation-induced partial localization in actinide compounds. Of particular interest are the 5f spectral function which can be related to photoemission data. Results for the U-based heavy fermion superconductor UPd₂Al₃ are presented emphasizing the consequences for the interpretation of experimental data.

The single-particle spectral functions in asymmetric nuclear matter are computed using the ladder approximation within the theory of finite temperature Green's functions. The internal energy and the momentum distributions of protons and neutrons are studied as a function of the density and the asymmetry of the system. The proton states are more strongly depleted when the asymmetry increases, whereas the occupation of the neutron states is enhanced compared to the symmetric case. Preliminary results for the entropy and the free energy are also presented.

The in-medium modifications of hadron properties such as masses and decay widths have been a major focus of the scientific work of Gerry Brown and the insights gained by him and his collaborators made them major drivers of this field for several decades. Their prediction of experimental signals in di-lepton pair production in relativistic heavy-ion collisions was instrumental in initiating large experimental campaigns which continue till today. In this chapter, we review recent results which elucidate the relation of hadronic spectral properties at finite temperature and density to the restoration of spontaneously broken chiral symmetry.