ψ(2S)\psi(2S) and Υ(3S)\Upsilon(3S) hadroproduction in the parton Reggeization approach: Yield, polarization, and the role of fragmentation

The hadroproduction of the radially excited heavy-quarkonium states $\psi(2S)$ and $\Upsilon(3S)$ at high energies is studied in the parton reggeization approach and the factorization formalism of nonrelativistic QCD at lowest order in the strong-coupling constant $\alpha_s$ and the relative heavy-quark velocity $v$. A satisfactory description of the $\psi(2S)$ transverse-momentum ($p_T$) distributions measured by ATLAS, CMS, and LHCb at center-of-mass energy $\sqrt{S}=7$ TeV is obtained using the color-octet long-distance matrix elements (LDMEs) extracted from CDF data at $\sqrt{S}=1.96$ TeV. The importance of the fragmentation mechanism and the scale evolution of the fragmentation functions in the upper $p_T$ range, beyond 30 GeV, is demonstrated. The $\Upsilon(3S)$ $p_T$ distributions measured by CDF at $\sqrt{S}=1.8$ TeV and by LHCb at $\sqrt{S}=7$ TeV and forward rapidities are well described using LDMEs fitted to ATLAS data at $\sqrt{S}=7$ TeV. Comparisons of polarization measurements by CDF and CMS at large $p_T$ values with our predictions consolidate the familiar problem in the $\psi(2S)$ case, but yield reasonable agreement in the $\Upsilon(3S)$ case.Comment: 28 pages, 12 figures, minor text additions, references added, matches journal versio

Comment on "Quantitative x-ray photoelectron spectroscopy: Quadrupole effects, shake up, Shirley background, and relative sensitivity factors from a database of true x-ray photoelectron spectra"

This Comment demonstrates that a comparison analysis by Seah and Gilmore between experimental data on the X-ray photoelectron spectroscopy intensities and theoretical data by Trzhaskovskaya et al. is misleading due to a number of serious errors made by Seah and Gilmore (Phys. Rev. B, 73, 174113).Comment: 7 pages, 3 figures, submitted to Phys. Rev.

Proximity effect of vanadium on spin-density-wave magnetism in Cr films

The spin-density wave (SDW) state in thin chromium films is well known to be strongly affected by proximity effects from neighboring layers. To date the main attention has been given to effects arising from exchange interactions at interfaces. In the present work we report on combined neutron and synchrotron scattering studies of proximity effects in Cr/V films where the boundary condition is due to the hybridization of Cr with paramagnetic V at the interface. We find that the V/Cr interface has a strong and long-range effect on the polarization, period, and the N\'{e}el temperature of the SDW in rather thick Cr films. This unusually strong effect is unexpected and not predicted by theory.Comment: 7 figure

Giant radiation heat transfer through the micron gaps

Near-field heat transfer between two closely spaced radiating media can exceed in orders radiation through the interface of a single black body. This effect is caused by exponentially decaying (evanescent) waves which form the photon tunnel between two transparent boundaries. However, in the mid-infrared range it holds when the gap between two media is as small as few tens of nanometers. We propose a new paradigm of the radiation heat transfer which makes possible the strong photon tunneling for micron thick gaps. For it the air gap between two media should be modified, so that evanescent waves are transformed inside it into propagating ones. This modification is achievable using a metamaterial so that the direct thermal conductance through the metamaterial is practically absent and the photovoltaic conversion of the transferred heat is not altered by the metamaterial.Comment: 4 pages, 3 figure

Effects of Spatial Dispersion on Reflection from Mushroom-type Artificial Impedance Surfaces

Several recent works have emphasized the role of spatial dispersion in wire media, and demonstrated that arrays of parallel metallic wires may behave very differently from a uniaxial local material with negative permittivity. Here, we investigate using local and non-local homogenization methods the effect of spatial dispersion on reflection from the mushroom structure introduced by Sievenpiper. The objective of the paper is to clarify the role of spatial dispersion in the mushroom structure and demonstrate that under some conditions it is suppressed. The metamaterial substrate, or metasurface, is modeled as a wire medium covered with an impedance surface. Surprisingly, it is found that in such configuration the effects of spatial dispersion may be nearly suppressed when the slab is electrically thin, and that the wire medium can be modeled very accurately using a local model. This result paves the way for the design of artificial surfaces that exploit the plasmonic-type response of the wire medium slab.Comment: submitted for publication, under revie

Magnetic-field-induced crossover from the inverse Faraday effect to the optical orientation in EuTe

A time-resolved optical pump-probe technique has been applied for studying the ultrafast dynamics in the magnetic semiconductor EuTe near the absorption band gap. We show that application of external magnetic field up to 6 T results in crossover from the inverse Faraday effect taking place on the femtosecond time scale to the optical orientation phenomenon with an evolution in the picosecond time domain. We propose a model which includes both these processes possessing different spectral and temporal properties. The circularly polarized optical pumping induces the optical electronic transition $4f^75d^0 \rightarrow 4f^65d^1$ forming the absorption band gap in EuTe. The observed crossover is related to a strong magnetic-field shift of the band gap in EuTe at low temperatures. It was found that manipulation of spin states on intrinsic defect levels takes place on a time scale of 19 ps in the applied magnetic field of 6 T.Comment: 11 pages, 4 figure

Measurement of air fluorescence light yield induced by an electromagnetic shower

For most of the Ultra High Energy Cosmic Ray (UHECR) experiments and projects (HiRes, AUGER, TA, JEM-EUSO, TUS,...), the detection technique of Extensive Air Showers (EAS) is based, at least, on the measurement of the air fluorescence induced signal. The knowledge of the Fluorescence Light Yield (FLY) is of paramount importance for the UHECR energy reconstruction. The MACFLY experiment was designed to perform such FLY measurements. In this paper we will present the results of dry air FLY induced by 50 GeV electromagnetic showers as a function of shower age and as a function of the pressure. The experiment was performed at CERN using an SPS electron test beam line. It is shown that the FLY is proportional to deposited energy in air (E_d) and that the ratio FLY/E_d and its pressure dependence remain constant independently of shower age and more generally independently of the excitation source used (single electron track or air shower).For most of the Ultra High Energy Cosmic Ray (UHECR) experiments and projects (HiRes, AUGER, TA, JEM-EUSO, TUS,...), the detection technique of Extensive Air Showers (EAS) is based, at least, on the measurement of the air fluorescence induced signal. The knowledge of the Fluorescence Light Yield (FLY) is of paramount importance for the UHECR energy reconstruction. The MACFLY experiment was designed to perform such FLY measurements. In this paper we will present the results of dry air FLY induced by 50 GeV electromagnetic showers as a function of shower age and as a function of the pressure. The experiment was performed at CERN using an SPS electron test beam line. It is shown that the FLY is proportional to deposited energy in air (E_d) and that the ratio FLY/E_d and its pressure dependence remain constant independently of shower age and more generally independently of the excitation source used (single electron track or air shower)

Measurement of air and nitrogen fluorescence light yields induced by electron beam for UHECR experiments

Most of the Ultra High Energy Cosmic Ray (UHECR) experiments and projects (HiRes, AUGER, TA, EUSO, TUS,...) use air fluorescence to detect and measure extensive air showers (EAS). The precise knowledge of the Fluorescence Light Yield (FLY) is of paramount importance for the reconstruction of UHECR. The MACFLY - Measurement of Air Cherenkov and Fluorescence Light Yield - experiment has been designed to perform such FLY measurements. In this paper we will present the results of FLY in the 290-440 nm wavelength range for dry air and pure nitrogen, both excited by electrons with energy of 1.5 MeV, 20 GeV and 50 GeV. The experiment uses a 90Sr radioactive source for low energy measurement and a CERN SPS electron beam for high energy. We find that the FLY is proportional to the deposited energy (E_d) in the gas and we show that the air fluorescence properties remain constant independently of the electron energy. At the reference point: atmospheric dry air at 1013 hPa and 23C, the ratio FLY/E_d=17.6 photon/MeV with a systematic error of 13.2%.Comment: 19 pages, 8 figures. Accepted for publication in Astroparticle Physic

Solar dynamo model with nonlocal alpha-effect

The first results of the solar dynamo model that allows for the diamagnetic effect of inhomogeneous turbulence and the nonlocal alpha-effect due to the rise of magnetic loops are discussed. The nonlocal alpha-effect is not subject to the catastrophic quenching related to the conservation of magnetic helicity. Given the diamagnetic pumping, the magnetic fields are concentrated near the base of the convection zone, although the distributed-type model covers the entire thickness of the convection zone. The magnetic cycle period, the equatorial symmetry of the field, its meridional drift, and the polar-to-toroidal field ratio obtained in the model are in agreement with observations. There is also some disagreement with observations pointing the ways of improving the model.Comment: To appear in Astronomy Letters, 10 pages, 5 figure