The field strength correlator from QCD sum rules

The gauge invariant two-point correlator for the gluon field strength tensor in analysed by means of the QCD sum rule method. To this end, we make use of a relation of this correlator to a two-point function for a quark-gluon hybrid in the limit of the quark mass going to infinity. From the sum rules a relation between the gluon correlation length and the gluon condensate is obtained.Comment: 5 pages, 1 figure, QCD Euroconferenc

Beyond two-stage models for lung carcinogenesis in the Mayak workers: Implications for Plutonium risk

Mechanistic multi-stage models are used to analyze lung-cancer mortality after Plutonium exposure in the Mayak-workers cohort, with follow-up until 2008. Besides the established two-stage model with clonal expansion, models with three mutation stages as well as a model with two distinct pathways to cancer are studied. The results suggest that three-stage models offer an improved description of the data. The best-fitting models point to a mechanism where radiation increases the rate of clonal expansion. This is interpreted in terms of changes in cell-cycle control mediated by bystander signaling or repopulation following cell killing. No statistical evidence for a two-pathway model is found. To elucidate the implications of the different models for radiation risk, several exposure scenarios are studied. Models with a radiation effect at an early stage show a delayed response and a pronounced drop-off with older ages at exposure. Moreover, the dose-response relationship is strongly nonlinear for all three-stage models, revealing a marked increase above a critical dose

Charm quark mass from QCD sum rules for the charmonium system

In this work, the charm quark mass is obtained from a QCD sum rule analysis of the charmonium system. In our investigation we include results from nonrelativistic QCD at next-to-next-to-leading order. Using the pole mass scheme, we obtain a value of $M_c=1.70\pm 0.13$ GeV for the charm pole mass. The introduction of a potential-subtracted mass leads to an improved scale dependence. The running ${\rm \bar{MS}}$-mass is then determined to be $m_c(m_c) = 1.23 \pm 0.09$ GeV.Comment: 15 pages, 3 figure

QCD sum rule analysis of the field strength correlator

The gauge invariant two-point correlator for the gluon field strength tensor is analysed by means of the QCD sum rule method. To this end, we make use of a relation of this correlator to a two-point function for a quark-gluon hybrid in the limit of the quark mass going to infinity. From the sum rules a relation between the gluon correlation length and the gluon condensate is obtained. We briefly compare our results to recent determinations of the field strength correlator on the lattice.Comment: 16 pages, 1 figur

Charm and bottom quark masses from QCD moment sum rules

In this work the charm and bottom quark masses are determined from QCD moment sum rules for the charmonium and upsilon systems. In our analysis we include both the results from non-relativistic QCD and perturbation theory at next-next-to-leading order. For the pole masses we obtain $M_c=1.75\pm 0.15$ GeV and $M_b=4.98\pm 0.125$ GeV. Using the potential-subtracted mass in intermediate steps of the calculation the MS-masses are determined to $m_c(m_c) = 1.19 \pm 0.11$ GeV and $m_b(m_b) = 4.24 \pm 0.10$ GeV.Comment: 4 pages, 2 figures, talk given at the High-Energy Physics International Conference in QCD, Montpellier, France, 2-9 July 200

Strong and Electromagnetic Mass Splittings in Heavy Mesons

The contributions to heavy meson mass differences by the strong hyperfine interaction, the light quark masses and the electromagnetic interaction are obtained from the empirical values of the $D$, $D^*$, $B$ and $B^*$ masses by means of a mass formula based on the heavy quark mass expansion. The three different types of contributions are determined with significant accuracy to next to leading order in that expansion.Comment: 12 pages, 2 figure

Perturbative Contributions to Field Correlators in Gluodynamics

The cancellation of perturbative contributions to the string tension in gluodynamics in the framework of vacuum field correlators method is shown at the order $O(g^4)$ by explicit calculation. The general pattern of these cancellations at all orders and relation with the renormalization properties of the Wilson loop is discussed.Comment: LaTeX 13 pages, no figure

QCD sum rule analysis of the charmonium system: The charm quark mass

In this work, the charm quark mass is obtained from a QCD sum rule analysis of the charmonium system. In our investigation we include results from non-relativistic QCD at next-to-next-to-leading order. Using the pole mass scheme, we obtain a value of $M_c=1.70\pm 0.13$ GeV for the charm pole mass. The introduction of a potential-subtracted mass leads to an improved scale dependence. The running {\rm \MSb}-mass is then determined to be $m_{c}(m_{c}) = 1.23 \pm 0.09$ GeV.Comment: 6 pages,3 figures, Talk given at the Euroconference on Quantum Chromodynamics (QCD 2000), Montpellier, July 2000, conference information adde

Evaluation of Self-Intersecting Wilson Loop in the Stochastic Vacuum Model

A Wilson loop is evaluated within the stochastic vacuum model for the case when the respective contour is self-intersecting and its size does not exceed the correlation length of the vacuum. The result has the form of a certain functional of the tensor area. It is similar to that for the non-self-intersecting loop only when the contour is a plane one. Even for such a contour, the obtained expression depends on the ratio of two functions parametrizing the bilocal field strength correlator taken at the origin, which is not so for the case of non-self-intersecting contour.Comment: 7 pages, LaTeX2e, no figures, minor stylistic corrections of the tex

Topological susceptibility in Yang-Mills theory in the vacuum correlator method

We calculate the topological susceptibility of the Yang-Mills vacuum using the field correlator method. Our estimate for the SU(3) gauge group, \chi^{1/4} = 196(7) MeV, is in a very good agreement with the results of recent numerical simulations of the Yang-Mills theory on the lattice.Comment: 5 pages (JETP Letters style