Search results for "Gluon"
showing 10 items of 697 documents
On the radiative decay of orthoquarkonium via two intermediate gluons: 1−− (Q $$\bar Q$$ ) → γ+1++ (q $$\bar q$$ )
1983
We investigate the decay of a heavy3S1 (Q\(\bar Q\) vector meson into a real photon and two off-shell intermediate gluons which create a3P1(q\(\bar q\)) axial vector meson. As an application we suggest to look for the decayJ/ϕ→ψ+D(1285) andΥ→γ1+P c /χ1++→γ1→γ2+J/ψ.
Calculation of theO(? s 2 ) parity-violating structure functions in $$e^ + e^ - \to q\bar qg$$
1986
We calculate the two nonvanishingO(αs2) parity-violating structure functions that contribute to\(e^ + e^ - \xrightarrow{{\gamma ,Z}}q\bar qg\). We discuss how these can be measured. We work with massless quarks and gluons and use dimensional regularization to regularize ultra-violet and infrared singularities. We carefully discuss how to deal withγ5 in the dimensional regularization scheme when infrared singularities are present.
AN INVESTIGATION INTO INTERMITTENCY
1992
The results of an investigation based on ALEPH data, e+ e- --> hadrons at square-root s = 91 GeV, into fluctuations in rapidity space are presented. It is found that the behaviour of the factorial moments is well represented by the Lund parton shower model. An estimate is made of the scale of fluctuations needed to describe the data. Differential moments are introduced and are used to demonstrate that within the average represented by the traditional factorial moments the pattern of fluctu10.1007/BF01483869ations is itself a strong function of rapidity. This pattern is shown to be primarily associated with the emission of hard gluons. The implied structure between the hadron clusters and pa…
The spin structure of the nucleon
2005
An introduction to deep inelastic scattering experiments investigating the spin structure of the proton and the neutron is given. Discussed are measurements with longitudinally polarized targets to determine the spin structure functiong 1 and sum rules and to do pQCD analyses with inclusive data, while a flavour separation and first extractions of the gluon polarization are performed with semi-inclusive data.
Polarized Structure Functions and the Nucleon Spin
1995
The link between the light-cone momentum distributions of constituent quark models and their corresponding parton distributions is used to study the polarized structure functions g 1 of proton and neutron. The formalism allows to analyze the effects of the structure of the quark model wave function and thus we discuss the SU (6) breaking mechanism associated with the One Gluon Exchange and large D-state admixtures originated in pionic models. We analyze the contribution to these structure functions of the gluon polarization arising from the anomaly.
nPDF constraints from the large hadron electron collider
2016
An updated analysis regarding the expected nuclear PDF constraints from the future Large Hadron Electron Collider (LHeC) experiment is presented. The new study is based on a more flexible small-$x$ parametrization which provides less biased uncertainty estimates in the region where there are currently no data constraints. The effect of the LHeC is quantified by directly including a sample of pseudodata according to the expected precision of this planned experiment. As a result, a significant reduction of the small-$x$ uncertainties in sea quarks and gluons is observed.
Forward J/ψ production at high energy: Centrality dependence and mean transverse momentum
2016
Forward rapidity $J/\psi$ meson production in proton-nucleus collisions can be an important constraint of descriptions of the small-$x$ nuclear wavefunction. In an earlier work we studied this process using a dipole cross section satisfying the Balitsky-Kovchegov equation, fit to HERA inclusive data and consistently extrapolated to the nuclear case using a standard Woods-Saxon distribution. In this paper we present further calculations of these cross sections, studying the mean transverse momentum of the meson and the dependence on collision centrality. We also extend the calculation to backward rapidities using nuclear parton distribution functions. We show that the parametrization is over…
Equation of state and transverse expansion effects in heavy ion collisions
1992
The effects of the equation of state on the expansion of hadronic matter and on the dilepton production rates in heavy ion collisions are studied. We have used two widely different descriptions of the hadron phase and considered scenarios with and without phase transition. The hadron phase is treated either as a gas of ideal massless pions or, more realistically, as a gas of different kinds of massive hadrons with finite size.
Three dimensional hydrodynamics of ultrarelativistic heavy ion collisions
1988
We have utilized a 2+1 dimensional numerical code based on Flux Corrected Transport method to find a solution for 3+1 dimensional cylindrically symmetric hydrodynamic flow of hadronic matter which is assumed to be formed in extremely high energy heavy ion collisions. The hydrodynamics is supplemented with a decoupling calculation in order to produce measurable particle distributions. This numerical procedure is applied here to Landau type initial conditions which have been fixed using a simple geometrical picture for a central O+Pb collision at 200 GeV/nucleon. The bag equation of state for nonbaryonic matter is used to simulate the deconfinement phase transition to quark gluon plasma. The …
Possible test for the suggestion that air showers with E > 1020eV are due to strongly interacting neutrinos
1998
The suggestion is made that air showers with energies beyond the Greisen-Zatsepin-Kuz'min spectral cut-off may have primary vertices some 6 km lower in height than those of proton initiated showers with energies below the GZK cut-off. This estimate is based on the assumption that post-GZK showers are due to neutrinos having acquired strong interactions from generation-changing dual gluon exchange as recently proposed.