Inclusive Spectra Of Charged Particles Research Articles

Ultraforward particle production from color glass condensate and Lund fragmentation

We present an analysis of data on single inclusive pion production measured by the LHCf collaboration in high-energy proton-proton and proton-nucleus at ultra-forward rapidities, $8.8 \leq\! y\leq \!10.8$. We also analyse forward RHIC data for calibration purposes. Our analysis relies on the use of a Monte Carlo event generator that combines a perturbative description of the elementary scattering process at partonic level based on the hybrid formalism of the Color Glass Condensate with an implementation of hadronization in the framework of the Lund string fragmentation model. This procedure allows us to reach values of the momenta of the produced particles as low as detected experimentally $p_t\sim0.1$ GeV. We achieve a good description of single inclusive spectra of charged particles and neutral pions at RHIC and the LHC respectively, and nuclear modification factors for proton-lead collisions at the LHC. Our results add evidence to the idea that particle production in the domain of very small Bjorken-$x$ is dominated by the saturation effects encoded in the unintegrated gluon distribution of the target. Being forward particle production of key importance in the development of air showers, we stress that this approach allows for a theoretically controlled extrapolation of our results to the scale of ultra-high energy cosmic rays, thus serving as starting point for future works on this topic.

Confronting current NLO parton fragmentation functions with inclusive charged-particle spectra at hadron colliders

The inclusive spectra of charged particles measured at high transverse momenta (pT≳2 GeV/c) in proton–proton and proton–antiproton collisions in the range of center-of-mass energies s=200–7000 GeV are compared with next-to-leading order perturbative QCD calculations using seven recent sets of parton-to-hadron fragmentation functions (FFs). Accounting for the uncertainties in the scale choices and in the parton distribution functions, we find that most of the theoretical predictions tend to overpredict the measured LHC and Tevatron cross sections by up to a factor of two. We identify the currently too-hard gluon-to-hadron FFs as the probable source of the problem, and justify the need to refit the FFs using the available LHC and Tevatron data in a region of transverse momenta, pT≳10 GeV/c, which is supposedly free from additional non-perturbative contributions and where the scale uncertainty is only modest.

Studies of QCD at ${\rm e}^ + {\rm e}^-$ centre-of-mass energies between 91 and 209 GeV

The hadronic final states observed with the ALEPH detector at LEP in e+e- annihilation are analysed using 730 pb-1 of data collected between 91 and 209 GeV in the framework of QCD. In particular event-shape variables and inclusive charged particle spectra are measured. The energy evolution of quantities derived from these measurements is compared to analytic QCD predictions. The mean charged particle multiplicity, the charged particle momentum spectrum and its peak position are compared to predictions of the modified-leading-logarithmic approximation. The strong coupling constant alpha_s is determined from a fit of the QCD prediction to distributions of six event-shape variables at eight centre-of-mass energies. A study of non-perturbative power law corrections is presented

Characteristics of Charged Particle Production in Relativistic Heavy-Ion Collisions

Inclusive spectra of charged particles at midrapidity in Au+Au collisions at sqrt(s_NN) = 130 GeV and 200 GeV were measured with the STAR detector at RHIC. The measured mean transverse momentum shows a characteristic dependence on charged particle multiplicity and beam energy in Au+Au collisions that is distinctly different from pp, pbarp and ee collisions. A comparison with model predictions is discussed.

Results from the CDF detector at fermilab

A review of preliminary results obtained in the analysis of the 1987 run is given. In particular inclusive spectra of charged particles produced in minimum bias events at energies of 630 and 1800 GeV are presented. The average Pt and the inclusive pseudorapidity distribution. Inclusive spectrum of jets. Production of W −> e νe. Prospective for future searches are also given.

Inclusive break-up reactions of 6Li at an incident energy of 26 MeV/nucleon

Inclusive charged particle spectra were measured from nuclear reactions induced by 156 MeV 6Li on 40Ca. At forward angles the spectra exhibit broad break-up distributions centered around the energy corresponding to the beam velocity. The double differential cross sections together with previous results for a 208Pb target were analyzed in the framework of the DWBA approach to projectile break-up taking into account elastic and inelastic reactions of the break-up fragments. The high energy tails of the background due to preequilibrium emission of complex charged particles were estimated on the basis of the coalescence model.

Single particle inclusive spectra of charged particles from antiproton-proton interactions at 5.7 GeV/c

A systematic study of single particle inclusive spectra of charged particles from ¯pp interactions at 5.7 GeV/c is presented and discussed in the framework of the Mueller-Regge approach to inclusive reactions. A comparison of our results with data at other energies points to specific properties of antiproton-proton interactions.

Single-particle inclusive spectra of charged particles in [formula omitted] interactions at 22.4 GeV/ c

The inclusive spectra for p p collisions at 22.4 GeV/ c are investigated. We show that the transverse momentum distributions resemble those in high-energy pp interactions and discuss the influence of annihilation processes on the p T 2 distributions. The invariant inclusive cross section for pions in the central region is found to be 28 ± 1 mb. A charge asymmetry is indicated by the y ∗ spectrum in the central region, the asymmetry parameter having the value 0.15 ± 0.01. Finally, we estimate the upper limit of the diffraction dissociation of the beam particle to be 3.68 −0.15 +0.45 mb.

Single-particle inclusive spectra of charged particles in ¯pp interactions at 22·4 GeV/c

The inclusive spectra for ¯pp collisions at 22·4 GeV/c are investigated. The transversal momentum distribution resembles the corresponding one in high energy pp interactions. The cross section in the central region is 28±mb. They *-distribution of secondary particles in the central region indicates a charge asymmetry with the asymmetry parameter having the value 0.15±0·01. The upper limit of the diffraction dissociation of the beam particle is estimated to be $$\left( {3 \cdot 68 \pm \begin{array}{*{20}c} {0 \cdot 45} \\ {0 \cdot 15} \\ \end{array} } \right)$$ mb.