Search results for "Gluon"
showing 10 items of 697 documents
JIMWLK evolution of the odderon
2016
We study the effects of a parity-odd "odderon" correlation in JIMWLK renormalization group evolution at high energy. Firstly we show that in the eikonal picture where the scattering is described by Wilson lines, one obtains a strict mathematical upper limit for the magnitude of the odderon amplitude compared to the parity even pomeron one. This limit increases with N_c, approaching infinity in the infinite N_c limit. We use a systematic extension of the Gaussian approximation including both 2- and 3-point correlations which enables us to close the system of equations even at finite N_c. In the large-N_c limit we recover an evolution equation derived earlier. By solving this equation numeric…
Soft-gluon resummation for boosted top-quark production at hadron colliders
2012
We investigate the production of highly energetic top-quark pairs at hadron colliders, focusing on the case where the invariant mass of the pair is much larger than the mass of the top quark. In particular, we set up a factorization formalism appropriate for describing the differential partonic cross section in the double soft and small-mass limit, and explain how to resum simultaneously logarithmic corrections arising from soft gluon emission and from the ratio of the pair-invariant mass to that of the top quark to next-to-next-to-leading logarithmic accuracy. We explore the implications of our results on approximate next-to-next-to-leading order formulas for the differential cross section…
The Mach cone signal and energy deposition scenarios in linearized hydrodynamics
2010
Particle correlation measurements associated with a hard or semi-hard trigger in heavy-ion collisions may reflect Mach cone shockwaves excited in the bulk medium by partonic energy loss. This is of great interest because, when compared with theory, such measurements can provide information on the transport properties of the medium. Specifically, the formation of Mach cone shockwaves is sensitive to the viscosity and speed of sound, as well as the detailed nature of the jet medium interaction. However, modeling the physics of shockwave excitation to obtain a meaningful comparison with the measured correlations is very challenging since the correlations arise from an interplay of perturbative…
"Table 11" of "Identified Charged Particles in Quark and Gluon Jets"
2003
No description provided.
"Table 6" of "Identified Charged Particles in Quark and Gluon Jets"
2003
Jet flavor tagging is used. (C=DUSCB), (C=DUSC), (C=UDS) mean quark-jet flavors. CONST(C=GLUON/JET) is the ratio gluon/jet for all charged particles. 'Mercedes' events, three-fold symmetric events, the angle between three jets is 120 +- 15 deg.
"Table 2" of "Identified Charged Particles in Quark and Gluon Jets"
2003
Jet flavor tagging is used. (C=DUSCB), (C=DUSC), (C=UDS) mean quark-jet flavors. CONST(C=GLUON/JET) is the ratio gluon/jet for all charged particles. 'Y' events, mirror symmetric events, the angle between the most energetic jet and other two jets is 150 +- 15 deg.
A search for t[bar over t] resonances in lepton+jets events with highly boosted top quarks collected in pp collisions at √s = 7 TeV with the ATLAS de…
2012
A search for resonant production of high-mass top-quark pairs is performed on 2.05 fb[superscript −1] of proton-proton collisions at √s = 7 TeV collected in 2011 with the ATLAS experiment at the Large Hadron Collider. This analysis of the lepton+jets final state is specifically designed for the particular topology that arises from the decay of highly boosted top quarks. The observed t[bar over t] invariant mass spectrum is found to be compatible with the Standard Model prediction and 95% credibility level upper limits are derived on the t[bar over t] production rate through new massive states. An upper limit of 0.7 pb is set on the production cross section times branching fraction of a narr…
A gauge-technique Ansatz for the three gluon vertex of the background field method
2011
The vertex connecting one background gluon with two quantum ones constitutes a central ingredient in the gauge-invariant Schwinger-Dyson equation that determines the non-perturbative dynamics of the gluon propagator. This vertex satisfies a Ward identity with respect to the background gluon, and a Slavnov-Taylor identity with respect to the two quantum gluons. We present a complete Ansatz for this vertex, which satisfies both aforementioned identities. This entire construction depends crucially on a set of constraints relating the various form-factors of the ghost Green's functions appearing in the Slavnov-Taylor identity satisfied by the vertex. The validity of these constraints is demonst…
The dynamical equation of the effective gluon mass
2011
In this article we derive the integral equation that controls the momentum dependence of the effective gluon mass in the Landau gauge. This is accomplished by means of a well-defined separation of the corresponding "one-loop dressed" Schwinger-Dyson equation into two distinct contributions, one associated with the mass and one with the standard kinetic part of the gluon. The entire construction relies on the existence of a longitudinally coupled vertex of nonperturbative origin, which enforces gauge invariance in the presence of a dynamical mass. The specific structure of the resulting mass equation, supplemented by the additional requirement of a positive-definite gluon mass, imposes a rat…
Structure of longitudinal chromomagnetic fields in high energy collisions
2014
We compute expectation values of spatial Wilson loops in the forward light cone of high-energy collisions. We consider ensembles of gauge field configurations generated from a classical Gaussian effective action as well as solutions of high-energy renormalization group evolution with fixed and running coupling. The initial fields correspond to a color field condensate exhibiting domain-like structure over distance scales of order the saturation scale. At later times universal scaling emerges at large distances for all ensembles, with a nontrivial critical exponent. Finally, we compare the results for the Wilson loop to the two-point correlator of magnetic fields.