253 research outputs found
Note on Moufang-Noether currents
The derivative Noether currents generated by continuous Moufang
tranformations are constructed and their equal-time commutators are found. The
corresponding charge algebra turns out to be a birepresentation of the tangent
Mal'ltsev algebra of an analytic Moufang loop.Comment: LaTeX2e, 6 pages, no figures, presented on "The XVth International
Colloquium on Integrable Systems and Quantum Symmetries, Prague, 15-17 June,
2006
Short Range Linear Potential in 3D Lattice Compact QED
We study the static potential between electric charges in the finite
temperature three dimensional compact gauge theory on the lattice. We show that
in the deconfinement phase at small separations between the charges the
potential contains a linearly rising piece which goes over into the Coulomb
potential as the distance between the charges is increased. The linear
potential is due to the gas of magnetic dipoles which are realized as
monopole-antimonopole bound states.Comment: 10 pages, 6 EPS figures, LaTeX2e, uses epsfig.st
Self-consistent evaluation of quark masses in three flavor crystalline color superconductivity
We present a self-consistent evaluation of the constituent quark masses in
the three flavor Larkin-Ovchinnikov-Fulde-Ferrell (LOFF) phases of QCD,
employing an improved Nambu-Jona Lasinio model. This result allows to determine
the window for values of the baryonic chemical potential where the LOFF state
is energetically favored.Comment: 17 pages, 5 figures, JHEP3 style. A second treatment of the
ultraviolet cutoff added. Three figures adapted to the new cutoff. Two
references added. Version accepted for publication on JHE
Pion form factor and QCD sum rules: case of pseudoscalar current
We present an analysis of QCD sum rules for pion form factor in
next-to-leading order of perturbation theory for the case of pseudoscalar pion
currents. The essential instanton contribution is reanalysed with account for
present more accurate values of parameters entering Single Instanton
Approximation (SIA). The theoretical curve obtained for Q^2 dependence of pion
form factor is in a good agreement with existing experimental data. To
calculate NLO corrections for double spectral densities we developed an
effective computational technic. The details of the method together with the
results for pion form factor in a more theoretically clean case of axial
interpolating currents will be presented elsewhere.Comment: LaTeX file, 12 pages, 5 figures, uses axodraw.st
Angular Momentum Mixing in Crystalline Color Superconductivity
In crystalline color superconductivity, quark pairs form at non-zero total
momentum. This crystalline order potentially enlarges the domain of color
superconductivity in cold dense quark matter. We present a perturbative
calculation of the parameters governing the crystalline phase and show that
this is indeed the case. Nevertheless, the enhancement is modest, and to lowest
order is independent of the strength of the color interaction.Comment: 9 pages, 2 figures, Revte
Limits on Cosmological Variation of Strong Interaction and Quark Masses from Big Bang Nucleosynthesis, Cosmic, Laboratory and Oklo Data
Recent data on cosmological variation of the electromagnetic fine structure
constant from distant quasar (QSO) absorption spectra have inspired a more
general discussion of possible variation of other constants. We discuss
variation of strong scale and quark masses. We derive the limits on their
relative change from (i) primordial Big-Bang Nucleosynthesis (BBN); (ii)
Oklo natural nuclear reactor, (iii) quasar absorption spectra, and (iv)
laboratory measurements of hyperfine intervals.Comment: 10 pages 2 figurs: second version have several references added and
some new comment
The Seven-sphere and its Kac-Moody Algebra
We investigate the seven-sphere as a group-like manifold and its extension to
a Kac-Moody-like algebra. Covariance properties and tensorial composition of
spinors under are defined. The relation to Malcev algebras is
established. The consequences for octonionic projective spaces are examined.
Current algebras are formulated and their anomalies are derived, and shown to
be unique (even regarding numerical coefficients) up to redefinitions of the
currents. Nilpotency of the BRST operator is consistent with one particular
expression in the class of (field-dependent) anomalies. A Sugawara construction
is given.Comment: 22 pages. Macropackages used: phyzzx, epsf. Three epsf figure files
appende
Decay constants, light quark masses and quark mass bounds from light quark pseudoscalar sum rules
The flavor and pseudoscalar correlators are investigated using
families of finite energy sum rules (FESR's) known to be very accurately
satisfied in the isovector vector channel. It is shown that the combination of
constraints provided by the full set of these sum rules is sufficiently strong
to allow determination of both the light quark mass combinations ,
and the decay constants of the first excited pseudoscalar mesons in
these channels. The resulting masses and decay constants are also shown to
produce well-satisfied Borel transformed sum rules, thus providing non-trivial
constraints on the treatment of direct instanton effects in the FESR analysis.
The values of and obtained are in good agreement with the
values implied by recent hadronic decay analyses and the ratios obtained
from ChPT. New light quark mass bounds based on FESR's involving weight
functions which strongly suppress spectral contributions from the excited
resonance region are also presented.Comment: 28 pages, 10 figure
Experimental Study of the Shortest Reset Word of Random Automata
In this paper we describe an approach to finding the shortest reset word of a
finite synchronizing automaton by using a SAT solver. We use this approach to
perform an experimental study of the length of the shortest reset word of a
finite synchronizing automaton. The largest automata we considered had 100
states. The results of the experiments allow us to formulate a hypothesis that
the length of the shortest reset word of a random finite automaton with
states and 2 input letters with high probability is sublinear with respect to
and can be estimated as $1.95 n^{0.55}.
The treatment of polycythaemia vera: an update in the JAK2 era
The clinical course of polycythaemia vera is marked by a high incidence of thrombotic complications, which represent the main cause of morbidity and mortality. Major predictors of vascular events are increasing age and previous thrombosis. Myelosuppressive drugs can reduce the rate of thrombosis, but there is concern that their use raises the risk of transformation into acute leukaemia. To tackle this dilemma, a risk-oriented management strategy is recommended. Low-risk patients should be treated with phlebotomy and low-dose aspirin. Cytotoxic therapy is indicated in high-risk patients, with the drug of choice being hydroxyurea because its leukaemogenicity is low. The recent discovery of JAK2 V617F mutation in the vast majority of polycythaemia vera patients opens new avenues for the treatment of this disease. Novel therapeutic options theoretically devoid of leukaemic risk, such as alpha-interferon and imatinib, affect JAK2 expression in some patients. Nevertheless, these drugs require further clinical experience and, for the time being, should be reserved for selected cases
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