Search results for "CHROMODYNAMICS"
showing 10 items of 1030 documents
Measurement of angular correlations of jets at s=1.96 TeV and determination of the strong coupling at high momentum transfers
2012
We present a measurement of the average value of a new observable at hadron colliders that is sensitive to QCD dynamics and to the strong coupling constant, while being only weakly sensitive to parton distribution functions. The observable measures the angular correlations of jets and is defined as the number of neighboring jets above a given transverse momentum threshold which accompany a given jet within a given distance Delta-R in the plane of rapidity and azimuthal angle. The ensemble average over all jets in an inclusive jet sample is measured and the results are presented as a function of transverse momentum of the inclusive jets, in different regions of Delta-R and for different tran…
Erratum to: A model for holographic QCD in the Veneziano limit at finite temperature and density
2015
Erratum to: JHEP04(2014)124
QCD condensates of dimension D=6 and D=8 from hadronic τ-decays
2007
Abstract The high-precision data from hadronic τ decays allows one to extract information on QCD condensates. Using the finalized ALEPH data, we obtain a more rigorous determination of the dimension 6 and 8 condensates for the ( V − A ) correlator. In particular, we find that the recent data fix a certain linear combination of these QCD condensates to a precision at the level of O(2)%. Our approach relies on more general assumptions than alternative approaches based on finite energy sum rules.
Reply to "Comment on 'Systematics of radial and angular-momentum Regge trajectories of light non-strange qqbar-states' "
2013
In his Comment, D. Bugg argues against our usage of the PDG collection of light non-strange states together with the half-width rule to analyze the linearity of radial and angular-moment Regge trajectories in the large-N_c limit. After taking into account his observations on our choice of data, the radial Regge trajectories are again analyzed. We still find that our conclusion on the lack of universality between radial- and angular-momentum Regge trajectories is valid.
QCD duality and the mass of the Charm Quark
2001
The mass of the charm quark is analyzed in the context of QCD finite energy sum rules using recent BESII e+e- annihilation data and a large momentum expansion of the QCD correlator which incorporates terms to order (alpha_s)^2 (m_c^2/q^2)^6. Using various versions of duality, we obtain the consistent result m_c(m_c)=(1.37 +- 0.09)GeV. Our result is quite independent of the ones based on the inverse moment analysis.
Bottom quark mass and QCD duality
2002
The mass of the bottom quark is analyzed in the context of QCD finite energy sum rules. In contrast to the conventional approach, we use a large momentum expansion of the QCD correlator including terms to order \alpha _{s}^{2}(m_{b}^{2}/q^{2})^{6} with the upsilon resonances from e^{+}e^{-} annihilation data as main input. A stable result m_{b}(m_{b})=4.19\pm 0.05 GeV} for the bottom quark mass is obtained. This result agrees with the independent calculations based on the inverse moment analysis.
AN OPERATOR PRODUCT EXPANSION ANALYSIS OF e+e-ANNIHILATION DATA
2013
Perturbative Quantum Chromodynamics combined with the operator product expansion is expected to provide a framework for the description of phenomena in hadron interactions including contributions of nonperturbative origin. Applied to the correlator of two electromagnetic currents, this framework can be confronted with e+e-annihilation into hadrons. Data from the total hadronic e+e-cross-section have become much more precise in recent years and the power corrections in the operator product expansion, i.e. the vacuum condensates are expected to be determined with higher precision than previously. We present an analysis of the condensates of dimensions d = 2, 4 and 6 and find reasonably stable…
Search for prompt production ofχcandX(3872)ine+e−annihilations
2007
We have searched for prompt production of χc1, χc2 and X(3872) in continuum e+e- annihilations using a 386fb-1 data sample collected around s=10.6GeV with the BABAR detector using the γJ/ψ decay mode. After accounting for the feed-down from ψ(2S)→γχc1,2, no significant signal for prompt χc1,2 production is observed. We present improved upper limits at 90% confidence level on the production cross sections of 77fb for χc1 and 79fb for χc2, for events where the χc momentum exceeds 2.0 GeV and there are at least three additional charged tracks. These limits are consistent with NRQCD predictions. We also set an upper limit on the prompt production of X(3872) through the decay X(3872)→γJ/ψ. © 200…
Comparison study of medium-modified QCD shower evolution scenarios
2009
The computation of hard processes in hadronic collisions is a major success of perturbative Quantum Chromodynamics (pQCD). In such processes, pQCD not only predicts the hard reaction itself, but also the subsequent evolution in terms of parton branching and radiation, leading to a parton shower and ultimately to an observable jet of hadrons. If the hard process occurs in a heavy-ion collision, a large part of this evolution takes place in the soft medium created along with the hard reaction. An observation of jets in heavy-ion collision thus allows a study of medium-modified QCD shower evolution. In vacuum, Monte-Carlo (MC) simulations are well established tools to describe such showers. Fo…
B-meson to light-meson transition form factors
2007
We report a comprehensive set of results for B-meson heavy-to-light transition form factors calculated using a truncation of, and expression for, the transition amplitudes in which all elements are motivated by the study of Dyson-Schwinger equations in QCD. In this relativistic approach, which realizes confinement and dynamical chiral symmetry breaking, all physical values of momentum transfer in the transition form factors are simultaneously accessible. Our results can be useful in the analysis and correlation of the large body of data being accumulated at extant facilities, and thereby in probing the standard model and beyond.