Heavy top limit and double-logarithmic contributions to Higgs production at m_H^2 / s << 1

Next-to-next-to-leading order (NNLO) QCD corrections to Higgs boson hadroproduction have recently been calculated in the heavy top-quark limit m_t -> \infty. The m_t -> \infty limit introduces double-logarithmic corrections in ln x, with x = m_H^2 / s. We identify these corrections order by order in alpha_s. As an application, we derive an analytic expression for the dominant x << 1 part of the NNLO coefficient.Comment: 7 page

Landslide detection by deep learning of non-nadiral and crowdsourced optical images

The recent development of mobile surveying platforms and crowdsourced geoinformation has produced a huge amount of non-validated data that are now available for research and application. In the field of risk analysis, with particular reference to landslide hazard, images generated by autonomous platforms (such as UAVs, ground-based acquisition systems, satellite sensors) and pictures obtained from web data mining are easily gathered and contribute to the fast surge in the amount of non-organized information that may engulf data storage facilities. Therefore, the high potential impact of such methods is severely reduced by the need of a massive amount of human intelligence tasks (HITs), which is necessary to filter and classify the data, whatever the final purpose. In this work, we present a new set of convolutional neural networks (CNNs) specifically designed for the automated recognition of landslides and mass movements in non-standard pictures that can be used in automated image classification, in supporting UAV autonomous guidance and in the filtering of data-mined information. Computer vision can be of great help in fostering the autonomous capability of intelligent systems to complement, or completely substitute, HITs. Image and object recognition are at the forefront of this research field. The deep learning procedure has been accomplished by applying transfer learning to some of the top-performer CNNs available in the literature. Results show that the deep learning machines, calibrated on a relevant dataset of validated images of landforms, may supply reliable predictions with computational time and resource requirements compatible with most of the UAV platforms and web data mining applications in landslide hazard studies. Average accuracy achieved by the proposed methods ranges between 87 and 90% and is consistently higher than that obtained by general-purpose state-of-the-art image recognition convolutional neural networks. The method can be applied to early warning, vulnerability assessment, residual risk estimation, model parameterisation and landslide mapping. Specific advantages will be the reduction of the present limitations in the intelligent guidance of landslide mapping drones, the classification of fake news, the validation of post-disaster information and the correct interpretation of an impending change in the environment

High-Energy Factorization and Small-X Deep Inelastic Scattering Beyond Leading Order

High-energy factorization in QCD is investigated beyond leading order and its relationship to the factorization theorem of mass singularities is established to any collinear accuracy. Flavour non-singlet observables are shown to be regular at small x order by order in perturbation theory. In the singlet sector, we derive the relevant master equations for the space-like evolution of gluons and quarks. Their solution enables us to sum next-to-leading corrections to the small-x behaviour of quark anomalous dimensions and deep inelastic scattering coefficient functions. We present results in both MSbar and DIS factorization schemes.Comment: 46 pages (+ 7 figures not included, available from the authors), Latex, Cavendish-HEP-94/0

Association of ultracold double-species bosonic molecules

We report on the creation of heterospecies bosonic molecules, associated from an ultracold Bose-Bose mixture of 41K and 87Rb, by using a resonantly modulated magnetic field close to two Feshbach resonances. We measure the binding energy of the weakly bound molecular states versus the Feshbach field and compare our results to theoretical predictions. We observe the broadening and asymmetry of the association spectrum due to thermal distribution of the atoms, and a frequency shift occurring when the binding energy depends nonlinearly on the Feshbach field. A simple model is developed to quantitatively describe the association process. Our work marks an important step forward in the experimental route towards Bose-Einstein condensates of dipolar molecules.Comment: 5 pages, 4 figure

Z\gamma\gamma production with leptonic decays and triple photon production at NLO QCD

We present a calculation of the O(alpha_s) QCD corrections to the production of a Z boson in association with two photons and to triple photon production at hadron colliders. All final-state photons are taken as real. For the Z boson, we consider the decays both into charged leptons and into neutrinos including all off-shell effects. Numerical results are obtained via a Monte Carlo program based on the structure of the VBFNLO program package. This allows us to implement general cuts and distributions of the final-state particles. We find that the NLO QCD corrections are sizable and significantly exceed the expectations from a scale variation of the leading-order result. In addition, differential distributions of important observables change considerably. The prediction of two-photon-associated Z production with Z decays into neutrinos from the charged-lepton rate works well, once we use an additional cut on the invariant mass of the charged-lepton pair.Comment: 14 pages, 10 figures, 2 table

Intense slow beams of bosonic potassium isotopes

We report on an experimental realization of a two-dimensional magneto-optical trap (2D-MOT) that allows the generation of cold atomic beams of 39K and 41K bosonic potassium isotopes. The high measured fluxes up to 1.0x10^11 atoms/s and low atomic velocities around 33 m/s are well suited for a fast and reliable 3D-MOT loading, a basilar feature for new generation experiments on Bose-Einstein condensation of dilute atomic samples. We also present a simple multilevel theoretical model for the calculation of the light-induced force acting on an atom moving in a MOT. The model gives a good agreement between predicted and measured flux and velocity values for our 2D-MOT.Comment: Updated references, 1 figure added, 10 pages, 9 figure

Collisional properties of sympathetically cooled 39^{39}K

We report the experimental evidence of the sympathetic cooling of $^{39}$K with $^{87}$Rb down to 1 $\mu$K, obtained in a novel tight confining magnetic trap. This allowed us to perform the first direct measurement of the elastic cross section of $^{39}$K below 50 $\mu$K. The result obtained for the triplet scattering length, $a_T = -51(7)$ Bohr radii, agrees with previous results derived from photoassociation spectra and from Feshbach spectroscopy of $^{40}$K.Comment: 7 pages, 4 figures, submitted to Phys. Rev.

Double species condensate with tunable interspecies interactions

We produce Bose-Einstein condensates of two different species, $^{87}$Rb and $^{41}$K, in an optical dipole trap in proximity of interspecies Feshbach resonances. We discover and characterize two Feshbach resonances, located around 35 and 79 G, by observing the three-body losses and the elastic cross-section. The narrower resonance is exploited to create a double species condensate with tunable interactions. Our system opens the way to the exploration of double species Mott insulators and, more in general, of the quantum phase diagram of the two species Bose-Hubbard model.Comment: 4 pages, 4 figure

Surprises from Quarkonium Decay into Photons

The perturbative QCD approach to quarkonium decay into a photon and hadrons is reconsidered. It is shown that a consistent treatment within perturbative QCD calls for the introduction of a fragmentation contribution which has been neglected so far. The ensuing phenomenological implications are discussed, and, in particular, the possibility of measuring the gluon fragmentation function of the photon is addressed. *To appear in the proceedings of the workshop QCD94, Montpellier, July '94.Comment: 4 pages + 3 figures, uuencoded postscript, Cambridge preprint Cavendish-HEP-94/0

QCD Theory

Quantum Chromodynamics is an established part of the Standard Model and an essential part of the toolkit for searching for new physics at high-energy colliders. I present a status report on the theory of QCD and review some of the important developments in the past year.Comment: 10 pages, 11 figures, plenary talk presented at ICHEP04, Beijing, China, August 200