Momentum Distribution Of Jets Research Articles

Jet overlap in heavy ion collisions at energies available at the CERN Large Hadron Collider and its consequences for the jet shape

Central lead-lead collisions at the LHC energies may pose a particular challenge for jet identification as multiple jets are produced per each collision event. We simulate the jet evolution in central Pb-Pb events at $\sqrt{s_{\rm NN}} = 2.76$ GeV collision energy with EPOS3 initial state, which typically contains multiple hard scatterings in each event. Therefore the partons from different jets have a significant chance to overlap in momentum space. We find that 30% of the jets with $p_\perp > 50$ GeV, identified by the standard anti-$k_\perp$ jet finding algorithm with jet cone size R=0.3, contain `intruder' particles from overlapping generator-level jets. This fraction increases with increasing beam energy and increasing R. The reconstructed momentum of the jet differs from that of the modelled jet by the loss due to jet partons which are outside of the jet cone and by the gain due to intruder partons. The sum of both may be positive or negative. These intruder partons particularly affect the radial jet momentum distribution because they contribute mostly at large angles $\Delta r$ with respect to the jet centre. The study stresses the importance of the jet overlap effect emerging in central lead-lead collisions at the LHC energies, while being negligible in peripheral PbPb or $p$Pb/$pp$ collisions.

Imprints of energy limitation in transverse momentum distributions of jets

Using a Tsallis nonextensive approach, we analyse distributions of transverse spectra of jets. We discuss the possible influence of energy conservation laws on these distributions. Transverse spectra of jets exhibit a power-law behavior of $1/p_T^n$ with the power indices $n$ similar to those for transverse spectra of hadrons.

A Study of Transverse Momentum Distributions of Jets Produced inp-p,p-p-,d-Au, Au-Au, and Pb-Pb Collisions at High Energies

The transverse momentum distributions of jets produced inp-p,p-p-,d-Au, Au-Au, and Pb-Pb collisions at high energies with different selected conditions are analyzed by using a multisource thermal model. The multicomponent (mostly two-component) Erlang distribution used in our description is in good agreement with the experimental data measured by the STAR, D0, CDF II, ALICE, ATLAS, and CMS Collaborations. Related parameters are extracted from the transverse momentum distributions and some information on different interacting systems is obtained. In the two-component Erlang distribution, the first component has usually two or more sources which are contributed by strong scattering interactions between two quarks or more quarks and gluons, while the second component has mostly two sources which are contributed by harder head-on scattering between two quarks.

Physics ofZ0/γ*-tagged jets at energies available at the CERN Large Hadron Collider

Electroweak bosons produced in conjunction with jets in high-energy collider experiments is one of the principle final-state channels that can be used to test the accuracy of perturbative Quantum Chromodynamics calculations and to assess the potential to uncover new physics through comparison between data and theory. In this paper we present results for the $Z^0/\gamma^*$+jet production cross sections at the LHC at leading and next-to-leading orders. In proton-proton reactions we elucidate up to ${\cal O}(G_F\alpha_s^2)$ the constraints that jet tagging via the $Z^0/\gamma^*$ decay dileptons provides on the momentum distribution of jets. In nucleus-nucleus reactions we demonstrate that tagged jets can probe important aspects of the dynamics of quark and gluon propagation in hot and dense nuclear matter and characterize the properties of the medium-induced parton showers in ways not possible with more inclusive measurements. Finally, we present specific predictions for the anticipated suppression of the $Z^0/\gamma^*$+jet production cross section in the quark-gluon plasma that is expected to be created in central lead-lead collisions at the LHC relative to the naive superposition of independent nucleon-nucleon scatterings.

Has the E791 experiment measured the pion wave function profile?

The cross section of hard diffractive dissociation of the pion into two jets is calculated. It is obtained that the distribution of longitudinal momenta for jets is not simply proportional to the profile of the pion wave function, but depends on it in a complicated way. In particular, it is shown that, under the conditions of the E791 experiment, the momentum distribution of jets is similar in its shape for the asymptotic and CZ wave functions, and even the ratio of the differential cross sections is not far from unity.

97/04259 Effects of jet momentum distribution on thermal characteristics of co-swirling flames

97/04259 Effects of jet momentum distribution on thermal characteristics of co-swirling flames

Chromodynamics and the transverse momentum of jets and hadrons in e+e− annihilation

Transverse momentum distributions of jets and hadrons produced in high energy e + e − annihilation provide an arena in which to test perturbative QCD calculations. We present a phenomenological study of recent data obtained at PETRA in the context of such calculations. We urge the study of perturbative QCD on isolated samples of events with large transverse momentum as lowest order results on moments, e.g., 〈 p T 2〉, are shown to be sensitive to the omission of higher orders.

Transverse momentum of jets in electroproduction from quantum chromodynamics

Detailed predictions of QCD on transverse momentum distributions of jets in leptoproduction are presented. The average p⊥2 is found to be asymptotically proportional to W2 (the hadronic invariant mass squared) with a coefficient function that depends little on x and y. Contributions from gluons in the nucleon are relatively smaller than for σL/σT.

The nocturnal jet

AbstractThree case studies of the nocturnal jet at dawn are presented. Observations were made over southern England where the terrain is considerably less homogeneous than that over which previous published data concerning the jet have been obtained, for example the Great Plains and Wangara.It is shown that previously suggested layer models of the boundary layer can be usefully quantified to give the diurnal evolution of a layer‐average wind. This model, which involves a decoupling of the flow in middle levels from surface constraints by thermal stratification at night, exhibits a nocturnal jet. Two surface‐stress parameterizations, which make the stress proportional to the velocity and to the velocity squared, give a similar wind evolution.The observed abrupt transition in boundary layer structure soon after sunrise is studied by considering the growth and transfer characteristics of perturbations to a homogeneous Boussinesq fluid, which is stratified and possesses an idealized jet wind structure. Depending on the value of an average Richardson number, Ri, two regimes of dynamically unstable eddies are indicated. When +0.35 ≳ Ri −0.03 the preferred eddies are oriented transverse to the shear and when Ri ≲−0.03 they are oriented parallel to the shear. the latter regime, associated with longitudinal convective circulations, is efficient at smoothing the jet momentum distribution to give the characteristic well‐mixed daytime wind profile.

Jet-Wing Lifting-Surface Theory Using Elementary Vortex Distributions

A lifting-surface theory for jet wings based on a finite-element method—the method of elementary vortex distribution or the EV D method—is presented. The method utilizes a set of independent but overlapped elementary horseshoe vortex distributions to represent the wing and jet sheet, and satisfies a set of mixed-type boundary conditions on both the wing and jet sheet. The solution includes chordwise and span wise loading distributions, from which sectional and total aerodynamic quantities (e.g., lift, pitching moment, induced drag, etc.) are derived. In view of the finite-element approach, the method can, in general, be applied to jet wings of arbitrary planform, camber, twist, partial-span flaps, and arbitrary trailing-edge jet-momentum distribution. The present method also reduces to a conventional lifting-surface theory when the jet momentum is zero. An extensive comparison has been made of solutions derived with the EVD method with other theoretical and experimental data for jet wings and conventional wings. Good agreement has been observed in the chordwise and span-wise loadings as well as total aerodynamic coefficients.