The small xx behavior of the gluon structure function from total cross sections

Within a QCD-based eikonal model with a dynamical infrared gluon mass scale we discuss how the small $x$ behavior of the gluon distribution function at moderate $Q^{2}$ is directly related to the rise of total hadronic cross sections. In this model the rise of total cross sections is driven by gluon-gluon semihard scattering processes, where the behavior of the small $x$ gluon distribution function exhibits the power law $xg(x,Q^2)= h(Q^2)x^{-\epsilon}$. Assuming that the $Q^{2}$ scale is proportional to the dynamical gluon mass one, we show that the values of $h(Q^2)$ obtained in this model are compatible with an earlier result based on a specific nonperturbative Pomeron model. We discuss the implications of this picture for the behavior of input valence-like gluon distributions at low resolution scales.Comment: 19 pages, 3 figures; revised version; to appear in Int. J. Mod. Phys.

TLEP, first step in a long-term vision for HEP

The discovery of H(126) has renewed interest in circular e+e- colliders that can operate as Higgs factories, which benefit from three unique characteristics: i) high luminosity and reliability, ii) the availability of several interaction points, iii) superior beam energy accuracy. TLEP is an e+e- storage ring of 80-km circumference that can operate with very high luminosity from the Z peak (90 GeV) to the top quark pair threshold (350 GeV). It can achieve transverse beam polarization at the Z peak and WW threshold, giving it unparalleled accuracy on the beam energy. A preliminary study indicates that an 80 km tunnel could be constructed around CERN. Such a tunnel would allow a 100 TeV proton-proton collider to be established in the same ring (VHE-LHC), offering a long term vision.Comment: This is a contribution to the the Snowmass process 2013: Frontier Capabilitie

Comments on "Wall-plug (AC) power consumption of a very high energy e+/e- storage ring collider" by Marc Ross

The paper arXiv:1308.0735 questions some of the technical assumptions made by the TLEP Steering Group when estimating in arXiv:1305.6498 the power requirement for the very high energy e+e- storage ring collider TLEP. We show that our assumptions are based solidly on CERN experience with LEP and the LHC, as well accelerators elsewhere, and confirm our earlier baseline estimate of the TLEP power consumption.Comment: 6 page

Elastic scattering and the proton form factor

We compute the differential and the total cross sections for $pp$ scattering using the QCD pomeron model proposed by Landshoff and Nachtmann. This model is quite dependent on the experimental electromagnetic form factor, and it is not totally clear why this form factor gives good results even at moderate transferred momentum. We exchange the eletromagnetic form factor by the asymptotic QCD proton form factor determined by Brodsky and Lepage (BL) plus a prescription for its low energy behavior dictated by the existence of a dynamically generated gluon mass. We fit the data with this QCD inspired form factor and a value for the dynamical gluon mass consistent with the ones determined in the literature. Our results also provide a new determination of the proton wave function at the origin, which appears in the BL form factor.Comment: 10 pages, 2 figures. Submitted to Physics Letters B. Submitted to Phys. Lett.

Development of microwave superconducting microresonators for neutrino mass measurement in the HOLMES framework

The European Research Council has recently funded HOLMES, a project with the aim of performing a calorimetric measurement of the electron neutrino mass measuring the energy released in the electron capture decay of 163Ho. The baseline for HOLMES are microcalorimeters coupled to Transition Edge Sensors (TESs) read out with rf-SQUIDs, for microwave multiplexing purposes. A promising alternative solution is based on superconducting microwave resonators, that have undergone rapid development in the last decade. These detectors, called Microwave Kinetic Inductance Detectors (MKIDs), are inherently multiplexed in the frequency domain and suitable for even larger-scale pixel arrays, with theoretical high energy resolution and fast response. The aim of our activity is to develop arrays of microresonator detectors for X-ray spectroscopy and suitable for the calorimetric measurement of the energy spectra of 163Ho. Superconductive multilayer films composed by a sequence of pure Titanium and stoichiometric TiN layers show many ideal properties for MKIDs, such as low loss, large sheet resistance, large kinetic inductance, and tunable critical temperature $T_c$. We developed Ti/TiN multilayer microresonators with $T_c$ within the range from 70 mK to 4.5 K and with good uniformity. In this contribution we present the design solutions adopted, the fabrication processes and the characterization results

Spatial Variation in Erosion Rates in Mars Equatorial Regions Inferred from Ejecta Retention of 1-3 Km Diameter Craters

The modification of impact craters has long been used to infer the geomorphic forcing on Mars [1], as well as estimate the spatial and temporal variability of this erosion and gradation [e.g., 2]. Here, we studied the population of small primary craters (1-3 km) to understand differences in ejecta retention across equatorial Mars. Specifically, we evaluated whether craters in our study population had observable ejecta deposits (defined on the basis of distinct tone or texture with respect to their surroundings).This is a proxy for the resurfacing rate because only relatively fresh craters retain their ejecta deposits. More broadly, this is part of a larger project we are undertaking [3] to examine crater morphometry and other characteristics from CTX-derived digital terrain models (DTMs), augmented by qualitative observations

X, Y and Z States

Many new states in the charmonium mass region were recently discovered by BaBar, Belle, CLEO-c, CDF, D0, BESIII, LHCb and CMS Collaborations. We use the QCD Sum Rule approach to study the possible structure of some of these states.Comment: Contribution for the proceedings of the "XII Quark Confinement and the Hadron Spectrum - CONF12" conferenc

Gully Formation at the Haughton Impact Structure (Arctic Canada) Through the Melting of Snow and Ground Ice, with Implications for Gully Formation on Mars

The formation of gullies on Mars has been the topic of active debate and scientific study since their first discovery by Malin and Edgett in 2000. Several mechanisms have been proposed to account for gully formation on Mars, from dry mass movement processes, release of water or brine from subsurface aquifers, and the melting of near-surface ground ice or snowpacks. In their global documentation of martian gullies, report that gullies are confined to ~2783S and ~2872N latitudes and span all longitudes. Gullies on Mars have been documented on impact crater walls and central uplifts, isolated massifs, and on canyon walls, with crater walls being the most common situation. In order to better understand gully formation on Mars, we have been conducting field studies in the Canadian High Arctic over the past several summers, most recently in summer 2018 and 2019 under the auspices of the Canadian Space Agency-funded Icy Mars Analogue Program. It is notable that the majority of previous studies in the Arctic and Antarctica, including our recent work on Devon Island, have focused on gullies formed on slopes generated by regular endogenic geological processes and in regular bedrock. How-ever, as noted above, meteorite impact craters are the most dominant setting for gullies on Mars. Impact craters provide an environment with diverse lithologies including impact-generated and impact-modified rocks and slope angle, and thus greatly variable hill slope processes could occur within a localized area. Here, we investigate the formation of gullies within the Haughton impact structure and compare them to gullies formed in unimpacted target rock in the nearby Thomas Lee Inle

Reaction of the NAD(P)H:flavin oxidoreductase from Escherichia coli with NADPH and riboflavin: identification of intermediates.

International audienceFlavin reductase catalyzes the reduction of free flavins by NAD(P)H. As isolated, Escherichia coli flavin reductase does not contain any flavin prosthetic group but accommodates both the reduced pyridine nucleotide and the flavin substrate in a ternary complex prior to oxidoreduction. The reduction of riboflavin by NADPH catalyzed by flavin reductase has been studied by static and rapid kinetics absorption spectroscopies. Static absorption spectroscopy experiments revealed that, in the presence of riboflavin and reduced pyridine nucleotide, flavin reductase stabilizes, although to a small extent, a charge-transfer complex of NADP+ and reduced riboflavin. In addition, reduction of riboflavin was found to be essentially irreversible. Rapid kinetics absorption spectroscopy studies demonstrated the occurrence of two intermediates with long-wavelength absorption during the catalytic cycle. Such intermediate species exhibit spectroscopic properties similar to those of charge-transfer complexes of oxidized flavin and NAD(P)H, and reduced flavin and NAD(P)+, respectively, which have been identified as intermediates during the reaction of flavoenzymes of the ferredoxin-NADP+ reductase family. Thus, a minimal kinetic scheme for the reaction of flavin reductase with NADPH and riboflavin can be proposed. After formation of the Michaelis complex of flavin reductase with NADPH and riboflavin, a first intermediate, identified as a charge-transfer complex of NADPH and riboflavin, is formed. It is followed by a second charge-transfer intermediate of enzyme-bound NADP+ and reduced riboflavin. The latter decays, yielding the Michaelis complex of flavin reductase with NADP+ and reduced riboflavin, which then dissociates to complete the reaction. These results support the initial hypothesis of a structural similarity between flavin reductase and the enzymes of the ferredoxin-NADP+ reductase family and extend it at a functional level