14854073
A type-Rainich approach to the Killing-Yano tensors
Following an approach by Collinson [1] we solve the Rainich problem for the Killing-Yano tensors: firstly we give the necessary and sufficient conditions for a 2+2 almost-product structure to determine the principal 2–planes of a skew-symmetric Killing-Yano tensor and, secondly, we obtain the additional conditions on a symmetric Killing tensor for it to be the square of a Killing-Yano tensor. We also analyze a similar problem for the conformal Killing-Yano and the conformal Killing tensors. Our results show that, in both cases, the principal 2–planes define a maxwellian structure. The associated Maxwell fields are obtained and we outline how this approach is of interest in studying the spacetimes that admit these kind of first integrals of the geodesic equation.
14972296
Vacuum type I spacetimes and aligned Papapetrou fields: symmetries
We analyse type I vacuum solutions admitting an isometry whose Killing 2-form is aligned with a principal bivector of the Weyl tensor, and we show that these solutions belong to a family of type I metrics which admit a group G3 of isometries. We give a classification of this family and study the Bianchi type for each class. The classes compatible with an aligned Killing 2-form are also determined. The Szekeres–Brans theorem is extended to non-vacuum spacetimes with vanishing Cotton tensor.
14680880
An intrinsic characterization of the Kerr metric
We give the necessary and sufficient (local) conditions for a metric tensor to be the Kerr solution. These conditions exclusively involve explicit concomitants of the Riemann tensor.
6470358
Aligned Electric and Magnetic Weyl Fields
The results on the non-existence of purely magnetic solutions are extended to the wider class of spacetimes which have homothetic electric and magnetic Weyl fields. This class is a particularization of the spacetimes admitting a direction for which the relative electric and magnetic Weyl fields are aligned. We give an invariant characterization of these metrics and study the properties of their Debever null vectors. The directions ‘observing’ aligned electric and magnetic Weyl fields are obtained for every Petrov-Bel type.
119234596
On the super-energy radiative gravitational fields
We extend our recent analysis (Ferrando J J and Saez J A 2012 Class. Quantum Grav. 29 075012) on the Bel radiative gravitational fields to the super-energy radiative gravitational fields defined by Garcia-Parrado (2008 Class. Quantum Grav. 25 015006). We give an intrinsic characterization of the new radiative fields and consider some distinguished classes of both radiative and non-radiative fields. Several super-energy inequalities are improved.
119760521
On the intrinsic labeling of space‐times: a characterization of the Kerr solution
The interest of obtaining an intrinsic (depending solely on the metric tensor) and fully explicit characterization of a space‐time is pointed out. We give the necessary and sufficient (local) conditions for a metric tensor to be the Kerr solution. These conditions exclusively involve concomitants of the Weyl tensor.
119232865
Diffractive photoproduction of dijets in ep collisions at HERA
Diffractive photoproduction of dijets was measured with the ZEUS detector at the ep collider HERA using an integrated luminosity of 77.2 pb-1. The measurements were made in the kinematic range Q2 < 1 GeV2, 0.20<y<0.85 and xIP<0.025, where Q2 is the photon virtuality, y is the inelasticity and xIP is the fraction of the proton momentum taken by the diffractive exchange. The two jets with the highest transverse energy, ETjet, were required to satisfy ETjet>7.5 and 6.5 GeV, respectively, and to lie in the pseudorapidity range -1.5<ηjet<1.5. Differential cross sections were compared to perturbative QCD calculations using available parameterisations of diffractive parton distributions of the proton. 
17317939
Inclusive jet cross sections in the Breit frame in neutral current deep inelastic scattering at HERA and determination of alpha s
Inclusive jet differential cross sections have been measured in neutral current deep inelastic e(+)p scattering for boson virtualities Q(2) > 125 GeV2. The data were taken using the ZEUS detector at HERA and correspond to an integrated luminosity of 38.6 pb(-1). Jets were identified in the Breit frame using the longitudinally invariant k(T) cluster algorithm. Measurements of differential inclusive jet cross sections a-re presented as functions of jet transverse energy (E-T.jet(B)), jet pseudorapidity and Q(2), for jets with E-T.jet(B) > 8 GeV. Next-to-leading-order QCD calculations agree well with the measurements both at high Q(2) and high E-T.jet(B). The value of alpha(s) (M-Z), determined from an analysis of dsigma/dQ(2) for Q(2) > GeV2, is alphas (M-Z) = 0.1212 +/- 0.0017(stat.)(-0.0031)(+0.0023)(syst.)(-0.0027)(+0.0028)(th.). (C) 2002 Elsevier Science B.V. All rights reserved.
10815425
Boosted objects: a probe of beyond the standard model physics
We present the report of the hadronic working group of the BOOST2010 workshop held at the University of Oxford in June 2010. The first part contains a review of the potential of hadronic decays of highly boosted particles as an aid for discovery at the LHC and a discussion of the status of tools developed to meet the challenge of reconstructing and isolating these topologies. In the second part, we present new results comparing the performance of jet grooming techniques and top tagging algorithms on a common set of benchmark channels. We also study the sensitivity of jet substructure observables to the uncertainties in Monte Carlo predictions.
118293635
Measurement of inelastic J/PSI production in deep inelastic scattering at HERA
The inelastic production of J/psi mesons in ep collisions has been studied with the ZEUS detector at HERA using an integrated luminosity of 109 pb(-1). The J/psi mesons were identified using the decay channel J/psi -> mu(+)mu(-). The measurements were performed in the kinematic range 2 < Q(2) < 80 GeV2, 50 < W < 250 GeV, 0.2 < z < 0.9 and -1.6 < Y-lab < 1.3, where Q(2) is the virtuality of the exchanged photon, W is the photon-proton centre-of-mass energy, z is the fraction of the photon energy carried by the J/psi meson in the proton rest frame and Ylab is the rapidity of the J/psi in the laboratory frame. The measured cross sections are compared to theoretical predictions within the non-relativistic QCD framework including colour-singlet and colour-octet contributions, as well as to predictions based on the k(T)-factorisation approach. Calculations of the colour-singlet process generally agree with the data, whereas inclusion of colour-octet terms spoils this agreement.
116620252
Probing QCD at the Highest $Q^2$ Deep Inelastic Scattering
Recent results from the HERA ep collider are reviewed in these proceedings. The results are from measurements that probe QCD at high-energy scales, as defined by $Q^2$, the four-momentum-transfer squared of the collisions. These cross-section measurements provide information about the parton distribution functions (PDFs) of the proton and can be used to constrain global fits of these PDFs. Recent measurements of the strong coupling $\alpha_S$ and jet substructure from HERA at similar energy scales are also reviewed.