Jet shapes have been measured in inclusive jet production in proton-proton collisions at sqrt(s) = 7 TeV using 3 pb^{-1} of data recorded by the ATLAS experiment at the LHC. Jets are reconstructed using the anti-kt algorithm with transverse momentum 30 GeV < pT < 600 GeV and rapidity in the region |y| < 2.8. The data are corrected for detector effects and compared to several leading-order QCD matrix elements plus parton shower Monte Carlo predictions, including different sets of parameters tuned to model fragmentation processes and underlying event contributions in the final state. The measured jets become narrower with increasing jet transverse momentum and the jet shapes present a moderate jet rapidity dependence. Within QCD, the data test a variety of perturbative and non-perturbative effects. In particular, the data show sensitivity to the details of the parton shower, fragmentation, and underlying event models in the Monte Carlo generators. For an appropriate choice of the parameters used in these models, the data are well described.
Measured Differential Jet Shape RHO as a function of r for jet transverse momentum from 30 to 40 GeV and absolute values of the jet rapidity from 0 to 2.8.
Measured Differential Jet Shape RHO as a function of r for jet transverse momentum from 40 to 60 GeV and absolute values of the jet rapidity from 0 to 2.8.
Measured Differential Jet Shape RHO as a function of r for jet transverse momentum from 60 to 80 GeV and absolute values of the jet rapidity from 0 to 2.8.
The proton-dissociative diffractive photoproduction of J/psi mesons has been studied in ep collisions with the ZEUS detector at HERA using an integrated luminosity of 112 pb^-1. The cross section is presented as a function of the photon-proton centre-of-mass energy and of the squared four-momentum transfer at the proton vertex. The results are compared to perturbative QCD calculations.
The differential cross section DSIG/DT as a function of T.
The differential cross section DSIG/DT as a function of W in the ABS(T) range 2.0 to 2.5 GeV**2.
The differential cross section DSIG/DT as a function of W in the ABS(T) range 2.5 to 3.0 GeV**2.
Mean values and differential distributions of event-shape variables have been studied in neutral current deep inelastic scattering using an integrated {luminosity} of 82.2 pb$^{-1}$ collected with the ZEUS detector at HERA. The kinematic range was $80 < Q^2 < 20 480\gev^2$ and $0.0024 < x < 0.6$, where $Q^2$ is the virtuality of the exchanged boson and $x$ is the Bjorken variable. The data are compared with a model based on a combination of next-to-leading-order QCD calculations with next-to-leading-logarithm corrections and the Dokshitzer-Webber non-perturbative power corrections. The power-correction method provides a reasonable description of the data for all event-shape variables studied. Nevertheless, the lack of consistency of the determination of $\alpha_s$ and of the non-perturbative parameter of the model, $\albar$, suggests the importance of higher-order processes that are not yet included in the model.
Mean value of the event shape variable 1-THRUST(C=T).
Mean value of the event shape variable B(C=T).
Mean value of the event shape variable RHO**2.
Exclusive electroproduction of $\phi$ mesons has been studied in $e^\pm p$ collisions at $\sqrt{s}=318 \gev$ with the ZEUS detector at HERA using an integrated luminosity of 65.1 pb$^{-1}$. The $\gamma^*p$ cross section is presented in the kinematic range $2<Q^2<70 \gev^2$, $35<W<145 \gev$ and ${|t|}<0.6 \gev^2$. The cross sections as functions of $Q^2$, $W$, $t$ and helicity angle $\theta_h$ are compared to cross sections for other vector mesons. The ratios $R$ of the cross sections for longitudinally and transversely polarized virtual photons are presented as functions of $Q^2$ and $W$. The data are also compared to predictions from theoretical models.
Exclusive GAMMA* P --> PHI P cross section in the Q**2 range 2 to 3 GeV**2.
Exclusive GAMMA* P --> PHI P cross section in the Q**2 range 3 to 5 GeV**2.
Exclusive GAMMA* P --> PHI P cross section in the Q**2 range 5 to 9 GeV**2.
In this Report, QCD results obtained from a study of hadronic event structure in high energy e^+e^- interactions with the L3 detector are presented. The operation of the LEP collider at many different collision energies from 91 GeV to 209 GeV offers a unique opportunity to test QCD by measuring the energy dependence of different observables. The main results concern the measurement of the strong coupling constant, \alpha_s, from hadronic event shapes and the study of effects of soft gluon coherence through charged particle multiplicity and momentum distributions.
Jet fractions using the JADE algorithm as a function of the jet resolution parameter YCUT at c.m. energy 130.1 GeV.
Jet fractions using the JADE algorithm as a function of the jet resolution parameter YCUT at c.m. energy 136.1 GeV.
Jet fractions using the JADE algorithm as a function of the jet resolution parameter YCUT at c.m. energy 161.3 GeV.
Inclusive event-shape variables have been measured in the current region of the Breit frame for neutral current deep inelastic ep scattering using an integrated luminosity of 45.0 pb^-1 collected with the ZEUS detector at HERA. The variables studied included thrust, jet broadening and invariant jet mass. The kinematic range covered was 10 < Q^2 < 20,480 GeV^2 and 6.10^-4 < x < 0.6, where Q^2 is the virtuality of the exchanged boson and x is the Bjorken variable. The Q dependence of the shape variables has been used in conjunction with NLO perturbative calculations and the Dokshitzer-Webber non-perturbative corrections (`power corrections') to investigate the validity of this approach.
Mean value of the event shape variables 1-THRUST(C=T) in different Q**2 and X bins.
Mean value of the event shape variables B(C=T) in different Q**2 and X bins.
Mean value of the event shape variables RHO**2 in different Q**2 and X bins.
We report differential cross sections for the production of D*(2010) produced in 500 GeV/c pi^- nucleon interactions from experiment E791 at Fermilab, as functions of Feynman-x (x_F) and transverse momentum squared (p_T^2). We also report the D* +/- charge asymmetry and spin-density matrix elements as functions of these variables. Investigation of the spin-density matrix elements shows no evidence of polarization. The average values of the spin alignment are \eta= 0.01 +- 0.02 and -0.01 +- 0.02 for leading and non-leading particles, respectively.
Acceptance corrected differential cross sections for D*+- production as a function of XL, Feynman X.
Acceptance corected differential cross sections for D*+- production as a function of PT**2.
Charge production asymmetry as a function of Feynman X.
Results are presented from a study of the structure of high energy hadronic events recorded by the L3 detector at sqrt(s)>192 GeV. The distributions of several event shape variables are compared to resummed O(alphaS^2) QCD calculations. We determine the strong coupling constant at three average centre-of-mass energies: 194.4, 200.2 and 206.2 GeV. These measurements, combined with previous L3 measurements at lower energies, demonstrate the running of alphaS as expected in QCD and yield alphaS(mZ) = 0.1227 +- 0.0012 +- 0.0058, where the first uncertainty is experimental and the second is theoretical.
The measured ALPHA_S at three centre-of-mass energies from fits to the individual event shape distributions. The first error is statistcal, the first DSYS error is the experimental systematic uncertainty, and the second DSYS error is the theoryuncertainty.
Updated ALPHA_S measurements from the BT, BW and C-Parameter distributions,from earlier L3 data at lower centre-of-mass energies.. The first error is the total experimental error (stat+sys in quadrature) and the DSYS error is the theory uncertainty.
Combined ALPHA_S values from the five event shape variables. The first error is statistical, the first DSYS error is the experimental systematic uncertainity, the second DSYS error is the uncertainty from the hadronisdation models, andthethird DSYS errpr is the uncertainty due to uncalculated higher orders in the QCDpredictions.
The shapes of jets with transverse energies, E_T(jet), up to 45 GeV produced in neutral- and charged-current deep inelastic e+p scattering (DIS) at Q**2 > 100 GeV**2 have been measured with the ZEUS detector at HERA. Jets are identified using a cone algorithm in the eta-phi plane with a cone radius of one unit. The jets become narrower as E_T(jet) increases. The jet shapes in neutral- and charged-current DIS are found to be very similar. The jets in neutral-current DIS are narrower than those in resolved processes in photoproduction and closer to those in direct-photon processes for the same ranges in E_T(jet) and jet pseudorapidity. The jet shapes in DIS are observed to be similar to those in e+e- interactions and narrower than those in pbarp collisions for comparable E_T(jet). Since the jets in e+e- interactions and e+p DIS are predominantly quark initiated in both cases, the similarity in the jet shapes indicates that the pattern of QCD radiation within a quark jet is to a large extent independent of the hard scattering process in these reactions.
Measured differential jet shapes, corrected to the hadron level, in neutral-current DIS for jets with ET greater than 14 GeV in different etarap regions.
Measured differential jet shapes, corrected to the hadron level, in neutral-current DIS for jets with ET greater than 14 GeV in different etarap regions.
Measured differential jet shapes, corrected to the hadron level, in neutral-current DIS for jets with ET greater than 14 GeV in different etarap regions.
A measurement of the spin alignment of charged D^* mesons produced in continuum e^+ e^- \to c \bar{c} events at \sqrt{s}=10.5 GeV is presented. This study using 4.72 fb^{-1} of CLEO II data shows that there is little evidence of any D^* spin alignment.
Systematic errors are not given.
Systematic errors are not given.
Two decay modes of D0 --> K- PI+ and D0 --> K- PI+ PI0 are combined.
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