The internal structure of jets at colliders: light and heavy quark inclusive hadronic distributions

In this paper, we report our results on charged hadron multiplicities of heavy quark initiated jets produced in high energy collisions. After implementing the so-called dead cone effect in QCD evolution equations, we find that the average multiplicity decreases significantly as compared to the massless case. Finally, we discuss on the transverse momentum distribution of light quark initiated jets and emphasize on the comparison between our predictions and CDF data.Comment: 6 pages, 3 figures-Talk presented by Redamy Perez-Ramos at Jets in Proton-Proton and Heavy-Ion Collisions, August 12-14, 2010, Prague, Czech Republi

Mean multiplicity of light and heavy quark initiated jets

After inserting the heavy quark mass dependence into QCD partonic evolution equations, we determine the mean charged hadron multiplicity of jets produced in high energy collisions. We thereby extend the so-called dead cone effect to the phenomenology of multiparticle production in QCD jets and find that the average multiplicity of heavy-quark initiated jets decreases significantly as compared to the massless case, even taking into account the weak decay products of the leading primary quark. We emphasize the relevance of our study as a complementary check of $b$-tagging techniques at hadron colliders like the Tevatron and the LHC.Comment: Plenary talk given at Light Cone 2010-LC2010, June 14-18, 2010, Valencia-Spain, to appear in the proceedings of the LC2010 conference, 8 pages and 3 figure

Correlations between two particles in jets

We study the correlation between two soft particles in QCD jets. We extend the Fong--Webber analysis to the region away from the hump in the single inclusive energy spectrum and show that the correlation function should flatten off and then decrease for large values of l=ln(1/x).Comment: 4 pages, 7 figures, Rencontres de Moriond 2005 "QCD and Hadronic interactions

Inclusive hadronic distributions at small x

After giving their general expressions valid at all x, double differential 1-particle inclusive distribution inside a quark and a gluon jet produced in a hard process, together with the inclusive kt distribution, are given at small x in the Modified Leading Logarithmic Approximation (MLLA), as functions of the transverse momentum kt of the outgoing hadron.Comment: 4 LaTeX page, 8 figures. To appear in proceedings of Rencontres de Moriond 2006, "QCD and hadronic interactions

From QCD color coherence to inclusive distributions and correlations in jets

In this paper we briefly review some examples of inclusive energy-momentum distributions and correlations in QCD intra-jet cascades. Emphasis is given to the role of gluon coherence effects in final states hadron spectra. These observables provide tests of the Local Parton Hadron Duality (LPHD) hypothesis.Comment: Invited talk at 6th International Workshop High-pT physics at LHC 2011, 4-7 April 2011, Utrecht, Netherlands. 6 pages and 4 figure

Energy evolution of the moments of the hadron distribution in QCD jets including NNLL resummation and NLO running-coupling corrections

The moments of the single inclusive momentum distribution of hadrons in QCD jets, are studied in the next-to-modified-leading-log approximation (NMLLA) including next-to-leading-order (NLO) corrections to the alpha_s strong coupling. The evolution equations are solved using a distorted Gaussian parametrisation, which successfully reproduces the spectrum of charged hadrons of jets measured in e+e- collisions. The energy dependencies of the maximum peak, multiplicity, width, kurtosis and skewness of the jet hadron distribution are computed analytically. Comparisons of all the existing jet data measured in e+e- collisions in the range sqrt(s)~2-200 GeV to the NMLLA+NLO* predictions allow one to extract a value of the QCD parameter Lambda_QCD, and associated two-loop coupling constant at the Z resonance alpha_s(m_Z^2)= 0.1195 +/- 0.0022, in excellent numerical agreement with the current world average obtained using other methods.Comment: 40 pages, 15 figures. Minor changes. Matches published version in JHE

Single Inclusive Distribution and Two-Particle Correlations Inside One Jet at "Modified Leading Logarithmic Approximation" of Quantum Chromodynamics II : Steepest Descent Evaluation at Small X

The MLLA single inclusive distribution inside one high energy (gluon) jet at small x is estimated by the steepest descent method. Its analytical expression is obtained outside the "limiting spectrum". It is then used to evaluate 2-particle correlations at the same level of generality. The dependence of both observables on the ratio between the infrared cutoff Q\_0 and Lambda\_QCD is studied. Fong & Webber's results for correlations are recovered at the limits when this ratio goes to 1 and when one stays close to the peak of the single inclusive distribution.Comment: LaTeX, 22 pages, 18 .eps figure

Three-particle correlations in QCD jets and beyond

In this paper, we present a more detailed version of our previous work for three-particle correlations in quark and gluon jets [1]. We give theoretical results for this observable in the double logarithmic approximation and the modified leading logarithmic approximation. In both resummation schemes, we use the formalism of the generating functional and solve the evolution equations analytically from the steepest descent evaluation of the one-particle distribution. In addition, in this paper we include predictions beyond the limiting spectrum approximation and study this observable near the hump of the single inclusive distribution. We thus provide a further test of the local parton hadron duality (LPHD) and make predictions for the LHC. The computation of higher rank correlators is presented in the double logarithmic approximation and shown to be rather cumbersome.Comment: 34 pages and 14 figure