469 research outputs found
Critical Behavior of J/psi across the Phase Transition from QCD sum rules
We study behavior of J/psi in hot gluonic matter using
QCD sum rules. Taking into account temperature dependences of the gluon
condensates extracted from lattice thermodynamics for the pure SU(3) system, we
find that the mass and width of J/psi exhibit rapid change across the critical
temperature.Comment: 5 pages, 3 figures. Poster contribution for Quark Matter 2008. To be
published in the proceeding
Light-induced reversible modification of the work function of a new perfluorinated biphenyl azobenzene chemisorbed on Au (111)
This work was financially supported by EC through the Marie-Curie ITN SUPERIOR (PITN-GA-2009-238177) and IEF MULTITUDES (PIEF-GA-2012-326666), the ERC project SUPRAFUNCTION (GA-257305), the Agence Nationale de la Recherche through the LabEx project Chemistry of Complex Systems (ANR-10-LABX-0026_CSC), and the International Center for Frontier Research in Chemistry (icFRC). The work in Mons is further supported by the Interuniversity Attraction Poles Programme (P7/05) initiated by the Belgian Science Policy Office, and by the Belgian National Fund for Scientific Research (FNRS). J.C. is an FNRS research director. The synthesis team in Switzerland acknowledges financial support by the Swiss National Science Foundation (SNF) and the Swiss Nanoscience Institute (SNI)
g_{\pi \Lambda \Sigma} and g_{K \Sigma \Xi} from QCD sum rules
The coupling constants g_{\pi \Lambda \Sigma} and g_{K \Sigma \Xi} are
calculated in the QCD sum rule approach using the three-point function method
and taking into account the SU(3) symmetry breaking effects. The pattern of
SU(3) breaking appears to be different from that based on SU(3) relations.Comment: revtex, 9 page
A QCD Sum Rule Approach to the Contribution to the Radiative Decay
QCD sum rules are used to calculate the contribution of short-distance
single-quark transition , to the amplitudes of the
hyperon radiative decay, . We re-evaluate the
Wilson coefficient of the effective operator responsible for this transition.
We obtain a branching ratio which is comparable to the unitarity limit.Comment: 15 pages, Revtex, 13 figures available as a uuencoded, gz-compressed
ps fil
Contribution of higher meson resonances to the electromagnetic -meson mass difference
Modifications of the DGMLY relation for calculation of electromagnetic
-meson mass difference based on the Chiral Symmetry Restoration phenomenon
at high energies as well as the Operator Product Expansion of quark densities
for vector () and axial-vector () meson fields difference are
proposed. In the calculations higher meson resonances in vector and
axial-vector channels are taken into account. It is shown that the inclusion of
the first and radial excitations improves the results for
electromagnetic -meson mass difference as compared with the previous ones.
Estimations on the electromagnetic and -meson decay constants and
the constant of effective chiral Lagrangian are obtained from the
generalized Weinberg sum rules.Comment: Latex2e, 10 pages, submitted to Yad. Phy
Transcriptomic signatures associated with regional cortical thickness changes in Parkinson's disease
Cortical atrophy is a common manifestation in Parkinson's disease (PD), particularly in advanced stages of the disease. To elucidate the molecular underpinnings of cortical thickness changes in PD, we performed an integrated analysis of brain-wide healthy transcriptomic data from the Allen Human Brain Atlas and patterns of cortical thickness based on T1-weighted anatomical MRI data of 149 PD patients and 369 controls. For this purpose, we used partial least squares regression to identify gene expression patterns correlated with cortical thickness changes. In addition, we identified gene expression patterns underlying the relationship between cortical thickness and clinical domains of PD. Our results show that genes whose expression in the healthy brain is associated with cortical thickness changes in PD are enriched in biological pathways related to sumoylation, regulation of mitotic cell cycle, mitochondrial translation, DNA damage responses, and ER-Golgi traffic. The associated pathways were highly related to each other and all belong to cellular maintenance mechanisms. The expression of genes within most pathways was negatively correlated with cortical thickness changes, showing higher expression in regions associated with decreased cortical thickness (atrophy). On the other hand, sumoylation pathways were positively correlated with cortical thickness changes, showing higher expression in regions with increased cortical thickness (hypertrophy). Our findings suggest that alterations in the balanced interplay of these mechanisms play a role in changes of cortical thickness in PD and possibly influence motor and cognitive functions.Neuro Imaging Researc
A unified meson-baryon potential
We study the spectra of mesons and baryons, composed of light quarks, in the
framework of a semirelativistic potential model including instanton induced
forces. We show how a simple modification of the instanton interaction in the
baryon sector allows a good description of the meson and the baryon spectra
using an interaction characterized by a unique set of parameters.Comment: 7 figure
The coupling constant g as derived from QCD sum rules
We employ QCD sum rules to calculate the coupling constant
g by studying the three point
-correlation function. Our results is consistent with the
value of this coupling constant obtained using vector meson dominance of the
electromagnetic current and the experimental -photoproduction data.Comment: 10 pages RevTex, 3 postscript figure
Nonfactorizable contributions to the decay mode D^0 -> K^0 \bar{K^0}
We point out that the decay mode D^0 -> K^0 \bar{K^0} has no factorizable
contribution. In the chiral perturbation language, treating D^0 as heavy, the
O(p) contribution is zero. We calculate the nonfactorizable chiral loop
contributions of order O(p^3). Then, we use a heavy-light type chiral quark
model to calculate nonfactorizable tree level terms, also of order O(p^3),
proportional to the gluon condensate. We find that both the chiral loops and
the gluon condensate contributions are of the same order of magnitude as the
experimental amplitude.Comment: 20 pages, 8 figure
Progress in the determination of the cross section
Improving previous calculations, we compute the cross section using QCD sum rules. Our sum rules for the , , and hadronic
matrix elements are constructed by using vaccum-pion correlation functions, and
we work up to twist-4 in the soft-pion limit. Our results suggest that, using
meson exchange models is perfectly acceptable, provided that they include form
factors and that they respect chiral symmetry. After doing a thermal average we
get mb at T=150\MeV.Comment: 22 pages, RevTeX4 including 7 figures in ps file
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