Quasiparticles and quantum phase transition in universal low-temperature properties of heavy-fermion metals

We demonstrate, that the main universal features of the low temperature experimental $H-T$ phase diagram of CeCoIn5 and other heavy-fermion metals can be well explained using Landau paradigm of quasiparticles. The main point of our theory is that above quasiparticles form so-called fermion-condensate state, achieved by a fermion condensation quantum phase transition (FCQPT). When a heavy fermion liquid undergoes FCQPT, the fluctuations accompanying above quantum critical point are strongly suppressed and cannot destroy the quasiparticles. The comparison of our theoretical results with experimental data on CeCoIn5 have shown that the electronic system of above substance provides a unique opportunity to study the relationship between quasiparticles properties and non-Fermi liquid behavior.Comment: 7 pages, 1 figure. arXiv admin note: substantial text overlap with arXiv:cond-mat/060260

Simulations of organic aerosol with CAMx over the Po Valley during the summer season

A new sensitivity analysis with the Comprehensive Air Quality Model with Extensions (CAMx) using a traditional two-product scheme (SOAP) and the newer Volatility Basis Set (VBS) algorithm for organic aerosol (OA) calculations is presented. The sensitivity simulations include the default versions of the SOAP and VBS schemes, as well as new parametrizations for the VBS scheme to calculate emissions and volatility distributions of semi- and intermediate-volatile organic compounds. The focus of the simulations is the summer season (May to July 2013), in order to quantify the sensitivity of the model in a period with relatively large photochemical activity. In addition to the model sensitivity, we validate the results with ad hoc OA measurements obtained from aerosol mass spectrometers at two monitoring sites. Unlike winter cases previously published, the comparison with experimental data showed limited sensitivity to total OA amount, with an estimated increase in OA concentrations limited to a few tenths of µg m−3, for both the primary and secondary components. We show that the lack of pronounced sensitivity is related to the effect of the new parametrizations on different emissions sectors. Furthermore, the minor sensitivity to the new parametrizations could be related to the greater partitioning of OA towards the gaseous phase in the summer period, thus reducing the organic fraction in the aerosol phase

Quasiparticles of strongly correlated Fermi liquids at high temperatures and in high magnetic fields

Strongly correlated Fermi systems are among the most intriguing, best experimentally studied and fundamental systems in physics. There is, however, lack of theoretical understanding in this field of physics. The ideas based on the concepts like Kondo lattice and involving quantum and thermal fluctuations at a quantum critical point have been used to explain the unusual physics. Alas, being suggested to describe one property, these approaches fail to explain the others. This means a real crisis in theory suggesting that there is a hidden fundamental law of nature. It turns out that the hidden fundamental law is well forgotten old one directly related to the Landau---Migdal quasiparticles, while the basic properties and the scaling behavior of the strongly correlated systems can be described within the framework of the fermion condensation quantum phase transition (FCQPT). The phase transition comprises the extended quasiparticle paradigm that allows us to explain the non-Fermi liquid (NFL) behavior observed in these systems. In contrast to the Landau paradigm stating that the quasiparticle effective mass is a constant, the effective mass of new quasiparticles strongly depends on temperature, magnetic field, pressure, and other parameters. Our observations are in good agreement with experimental facts and show that FCQPT is responsible for the observed NFL behavior and quasiparticles survive both high temperatures and high magnetic fields.Comment: 17 pages, 17 figures. Dedicated to 100th anniversary of A.B.Migdal birthda

The dust un-biased cosmic star formation history from the 20 cm VLA-COSMOS survey

We derive the cosmic star formation history (CSFH) out to z=1.3 using a sample of ~350 radio-selected star-forming galaxies, a far larger sample than in previous, similar studies. We attempt to differentiate between radio emission from AGN and star-forming galaxies, and determine an evolving 1.4 GHz luminosity function based on these VLA-COSMOS star forming galaxies. We precisely measure the high-luminosity end of the star forming galaxy luminosity function (SFR>100 M_Sol/yr; equivalent to ULIRGs) out to z=1.3, finding a somewhat slower evolution than previously derived from mid-infrared data. We find that more stars are forming in luminous starbursts at high redshift. We use extrapolations based on the local radio galaxy luminosity function; assuming pure luminosity evolution, we derive $L_* \propto (1+z)^{2.1 \pm 0.2}$ or $L_* \propto (1+z)^{2.5 \pm 0.1}$, depending on the choice of the local radio galaxy luminosity function. Thus, our radio-derived results independently confirm the ~1 order of magnitude decline in the CSFH since z~1.Comment: 9 pages, 7 figures; submitted to ApJ (revised following the referee report

Coexistence of Superconductivity and Charge Density Wave in SrPt2As2

SrPt2As2 is a novel arsenide superconductor, which crystallizes in the CaBe2Ge2-type structure as a different polymorphic form of the ThCr2Si2-type structure. SrPt2As2 exhibits a charge-density-wave (CDW) ordering at about 470 K and enters into a superconducting state at Tc = 5.2 K. The coexistence of superconductivity and CDW refers to Peierls instability with a moderately strong electron-phonon interaction. Thus SrPt2As2 can be viewed as a nonmagnetic analog of iron-based superconductors, such as doped BaFe2As2, in which superconductivity emerges in close proximity to spin-density-wave ordering.Comment: 4 pages, 5 figure

Heavy nuclei at the end of the cosmic ray spectrum?

We provide an account of the possible acceleration of iron nuclei up to energies $\sim300$ EeV in the nearby, metally-rich starburst galaxy NGC 253. It is suggested that particles can escape from the nuclear region with energies of $\sim10^{15}$ eV and then could be reaccelerated at the terminal shock of the galactic superwind generated by the starburst, avoiding in this way the photodisintegration expected if the nuclei were accelerated in the central region of high photon density. We have also made estimates of the expected arrival spectrum, which displays a strong dependency with the energy cutoff at the source.Comment: Revised version, to appear in Physical Review

Interplay of Superconductivity and Fermi-Liquid Transport in Rh-Doped CaFe2As2 with Lattice-Collapse Transition

Ca(Fe$_{1-x}$Rh$_x$)$_2$As$_2$ undergoes successive phase transitions with increasing Rh doping in the $T$ $=$ 0 limit. The antiferromagnetic-metal phase with orthorhombic structure at 0.00 $\le$ $x$ $\le$ 0.020 is driven to a superconducting phase with uncollapsed-tetragonal (ucT) structure at 0.020 $\le$ $x$ $\le$ 0.024; a non-superconducting collapsed-tetragonal (cT) phase takes over at $x$ $\geq$ 0.024. The breakdown of Fermi-liquid transport is observed in the ucT phase above $T_{\rm c}$. In the adjacent cT phase, Fermi-liquid transport is restored along with a disappearance of superconductivity. This interplay of superconductivity and Fermi-liquid transport suggests the essential role of magnetic fluctuations in the emergence of superconductivity in doped CaFe$_2$As$_2$.Comment: 11 pages, 4 figure