306 research outputs found
Excitations of torelon
The excitations of gluonic flux tube in a periodic lattice are examined.
Monte Carlo simulations from an anisotropic lattice are presented and the
comparison with effective string models is discussed.Comment: Talk at Lattice 2003; 3 pages, 4 figure
Potential model calculations and predictions for heavy quarkonium
We investigate the spectroscopy and decays of the charmonium and upsilon
systems in a potential model consisting of a relativistic kinetic energy term,
a linear confining term including its scalar and vector relativistic
corrections and the complete perturbative one-loop quantum chromodynamic short
distance potential. The masses and wave functions of the various states are
obtained using a variational technique, which allows us to compare the results
for both perturbative and nonperturbative treatments of the potential. As well
as comparing the mass spectra, radiative widths and leptonic widths with the
available data, we include a discussion of the errors on the parameters
contained in the potential, the effect of mixing on the leptonic widths, the
Lorentz nature of the confining potential and the possible
interpretation of recently discovered charmonium-like states.Comment: Physical Review published versio
String-like behaviour of 4d SU(3) Yang-Mills flux tubes
We present here results on the fine structure of the static q\bar q potential
in d=4 SU(3) Yang-Mills theory. The potential is obtained from Polyakov loop
correlators having separations between 0.3 and 1.2 fermi. Measurements were
carried out on lattices of spatial extents of about 4 and 5.4 fermi. The
temporal extent was 5.4 fermi in both cases. The results are analyzed in terms
of the force between a q\bar q pair as well as in terms of a scaled second
derivative of the potential. The data is accurate enough to distinguish between
different effective string models and it seems to favour the expression for
ground state energy of a Nambu-Goto string.Comment: 9 pages in LaTeX with 2 figures and 2 tables in JHEP style. Replaced
to match with shortened published versio
Mindfulness May Moderate the Relationship Between Intrinsic Motivation and Physical Activity: A Cross-Sectional Study
International audienceThis study aims to characterize the relationships between intrinsic motivation towards physical activity, mindfulness, and physical activity level. We measured self-reported mindfulness, motivational regulation towards exercise, and physical activity level in 280 French students. Analyses conducted on 244 participants revealed that self-reported mindfulness moderates the relationship between intrinsic motivation towards exercise and physical activity levels. These findings may have implications for interventionists seeking to promote increased physical activity with mindfulness-based techniques. In fact, it seems that increasing mindfulness skills of individuals could improve their intrinsic motivation to exercise and thus, physical activity
A numerical study of confinement in compact QED
Compact U(1) lattice gauge theory in four dimensions is studied by means of
an efficient algorithm which exploits the duality transformation properties of
the model. We focus our attention onto the confining regime, considering the
interquark potential and force, and the electric field induced by two
infinitely heavy sources. We consider both the zero and finite temperature
setting, and compare the theoretical predictions derived from the effective
string model and the dual superconductor scenario to the numerical results.Comment: 31 pages, 16 eps figures; v2: references added; v3: footnote added,
summation ranges in section 4 made explicit, version published in JHE
Gluelump Spectrum in the Bag Model
We explore the ordering of the lowest levels in a simple bag model of the
``gluelump'' of Michael and also discuss, again within the context of the bag
model, the related problem of hybrid potentials in the limit of very small
spacing between quark and anti-quark sources.Comment: 10 page
Meson spectroscopy with COMPASS
The COMPASS fixed-target experiment at CERN SPS is dedicated to the study of
hadron structure and dynamics. In the physics programme using hadron beams, the
focus is on the detection of new states, in particular the search for
exotic states and glueballs. After a short pilot run in 2004 (190 GeV/c
negative pion beam, lead target), we started our hadron spectroscopy programme
in 2008 by collecting an unprecedented statistics with a negative hadron beam
(190 GeV/c) on a liquid hydrogen target. A similar amount of data with positive
hadron beam (190 GeV/c) has been taken in 2009, as well as some additional data
with negative beam on nuclear targets. The spectrometer features a large
angular acceptance and high momentum resolution and also good coverage by
electromagnetic calorimetry, crucial for the detection of final states
involving or . A first important result is the observation of a
significant spin exotic signal consistent with the disputed
in the pilot run data. This result was recently published. We
present an overview of the status of various ongoing analyses on the 2008/09
data.Comment: 6 pages, 6 figures, to appear in the proceedings of the International
Nuclear Physics Conference 2010, Vancouver, Canada, 04-09 Jul 201
Characterisation of anhydro-sialic acid transporters from mucosa-associated bacteria
Sialic acid (Sia) transporters are critical to the capacity of host-associated bacteria to utilise Sia for growth and/or cell surface modification. While N-acetyl-neuraminic acid (Neu5Ac)-specific transporters have been studied extensively, little is known on transporters dedicated to anhydro-Sia forms such as 2,7-anhydro-Neu5Ac (2,7-AN) or 2,3-dehydro-2-deoxy-Neu5Ac (Neu5Ac2en). Here, we used a Sia-transport-null strain of Escherichia coli to investigate the function of members of anhydro-Sia transporter families previously identified by computational studies. First, we showed that the transporter NanG, from the Glycoside-Pentoside-Hexuronide:cation symporter family, is a specific 2,7-AN transporter, and identified by mutagenesis a crucial functional residue within the putative substrate-binding site. We then demonstrated that NanX transporters, of the Major Facilitator Superfamily, also only transport 2,7-AN and not Neu5Ac2en nor Neu5Ac. Finally, we provided evidence that SiaX transporters, of the Sodium-Solute Symporter superfamily, are promiscuous Neu5Ac/Neu5Ac2en transporters able to acquire either substrate equally well. The characterisation of anhydro-Sia transporters expands our current understanding of prokaryotic Sia metabolism within host-associated microbial communities
Gauge Theories on a 2+2 Anisotropic Lattice
The implementation of gauge theories on a four-dimensional anisotropic
lattice with two distinct lattice spacings is discussed, with special attention
to the case where two axes are finely and two axes are coarsely discretized.
Feynman rules for the Wilson gauge action are derived and the renormalizability
of the theory and the recovery of the continuum limit are analyzed. The
calculation of the gluon propagator and the restoration of Lorentz invariance
in on-shell states is presented to one-loop order in lattice perturbation
theory for on both 2+2 and 3+1 lattices.Comment: 27 pages, uses feynmf. Font compatibility adjuste
Special relativity constraints on the effective constituent theory of hybrids
We consider a simplified constituent model for relativistic
strong-interaction decays of hybrid mesons. The model is constructed using
rules of renormalization group procedure for effective particles in light-front
quantum field theory, which enables us to introduce low-energy phenomenological
parameters. Boost covariance is kinematical and special relativity constraints
are reduced to the requirements of rotational symmetry. For a hybrid meson
decaying into two mesons through dissociation of a constituent gluon into a
quark-anti-quark pair, the simplified constituent model leads to a rotationally
symmetric decay amplitude if the hybrid meson state is made of a constituent
gluon and a quark-anti-quark pair of size several times smaller than the
distance between the gluon and the pair, as if the pair originated from one
gluon in a gluonium state in the same effective theory.Comment: 11 pages, 5 figure
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