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A well-behaved topological quantum algebra structure on a quantized enveloping topological algebra is given by a star product on the corresponding exact compact connected Poisson–Lie group of its triangular Lie bialgebra.

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The algebraic structure underlying Winternitz system is found to be universal for maximally superintegrable systems.

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Certain dissipative Ginzburg–Landau models predict existence of planar interfaces moving with constant velocity. In most cases the interface solutions are hard to obtain because pertinent evolution equations are nonlinear. We present a systematic perturbative expansion which allows us to compute effects of small terms added to the free energy functional of a soluble model. As an example, we take the exactly soluble model with single order parameter \(\varphi \) and the potential \(V_0(\varphi ) = A\varphi ^2 + B \varphi ^3 + \varphi ^4\), and we perturb it by adding \(V_1(\phi ) = \frac {1}{2}\varepsilon _1\varphi ^2 \partial _i\varphi \partial _i\varphi +\frac {1}{5}\varepsilon _2 \varphi ^5 + \frac {1}{6}\varepsilon _3 \varphi ^6. \) We discuss the corresponding changes of the velocity of the planar interface.

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Considering a charged scalar massless quantum field model with global gauge symmetry U(1), at finite temperature \(T\), we analyze the light cone singular structure of the photonic two-point function, as derived in two different resummation schemes of leading thermal effects.

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In the framework of the chiral quark–soliton model of the nucleon we investigate the properties of the polarized quark distribution. In particular we analyse the so called anomalous difference between the representations for the quark distribution functions in terms of occupied and of non-occupied quark states. By an explicit analytical calculation it is shown that this anomaly is absent in the polarized isoscalar distribution \(\Delta u + \Delta d\), which is ultraviolet finite. In the case of the polarized isovector quark distribution \(\Delta u-\Delta d\) the anomaly can be cancelled by a Pauli–Villars subtraction which is also needed for the regularization of the ultraviolet divergence.

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Consistent interactions that can be added between a Chern–Simons term and a massless complex scalar field are investigated by means of cohomological arguments in the framework of the antibracket-antifield BRST formalism.

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We discuss the implementations of the Bose–Einstein effect from asymmetric sources in Monte Carlo generators. A comparison of LEP data with results from the PYTHIA/JETSET code with the standard procedure imitating the effect and with the results from the weight method (with weights depending in various ways on components of momenta differences) is presented. We show that in this last method one can reproduce the experimental hierarchy of the source radii.

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A particular form of mixing matrix for three active and one sterile neutrinos is proposed. Its \(3\times 3 \) part describing three active neutrinos arises from the popular bimaximal mixing matrix that works satisfactorily in solar and atmospheric experiments if the LSND effect is ignored. Then, the sterile neutrino, effective in the fourth row and fourth column of the proposed mixing matrix, is responsible for the possible LSND effect by inducing one extra neutrino mass state to exist actively. The LSND effect, if it exists, turns out to reveal its perturbative nature related to small mixing of three active neutrinos with their sterile partner.

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I discuss some aspects of recent developments in color superconductivity in high density quark matter. I calculate the Cooper pair gap and the critical points at high density, where magnetic gluons are not screened. The ground state of high density QCD with three light flavors is shown to be a color-flavor locking state, which can be mapped into the low-density hadronic phase. The meson mass at the CFL superconductor is also calculated. The CFL color superconductor is bosonized, where the Fermi sea is identified as a \(Q\)-matter and the gapped quarks as topological excitations, called superqualitons, of mesons. Finally, as an application of color supercoductivity, I discuss the neutrino interactions in the CFL color superconductor.

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The proper incorporation of spin effects in \(\tau \) lepton decays is often of importance. In the present work the case of the \(Z\)/\(\gamma \to \tau ^+ \tau ^-\) production mechanism is studied in detail. As an example, the effects due to the spin correlations on the potential for the Minimal Supersymmetric Standard Model (MSSM) Higgs boson(s) searches in the \(\tau \tau \) decay channel at the Large Hadron Collider (LHC) are discussed. For these processes, the Standard Model \(Z\)/\(\gamma ^* \to \tau \tau \)-pair production is a dominant background. The spin effects in high energy physics reactions, can be implemented up to certain approximation, independently of the algorithm and matrix elements used by the production program. Information stored on every generated event can be sufficient. The algorithm based on such approximation is documented. Question of the theoretical uncertainty is partly discussed.

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We model the effects of a large number of zero modes for \(N_f\) species of quarks at finite vacuum angle \(\theta \), using a matrix model with Gaussian weights constrained by the topological susceptibility and compressibility. The quenched free energy exhibits a cusp at \(\theta \lt \pi \) that is sensitive to the accuracy of the numerical analysis and the maximum density of winding modes. Our results bear much in common with recent lattice simulations by Schierholz and others. The unquenched free energy exhibits similar sensitivities, but for small quark masses or a large density of zero modes the results are in agreement with those derived using anomalous Ward identities and effective Lagrangians.

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Channels with multi-\(b\)-jet final states are very important in the discovery strategies for the Higgs boson search in ATLAS experiment at LHC. Excellent jets reconstruction efficiencies and mass resolution capability of the di-jet system are crucial aspects of the detector performance for the signal observability in these channels. Full simulation and reconstruction of the four representative channels with \(b\)-jets in final states is discussed: \(WH\), \(t\bar tH\) with \(H \to b \bar b\) and \(A\rightarrow Zh\), \(H\rightarrow hh \) with \(h \to b \bar b\). These channels are used as benchmark ones to study the different complexity of events, level of combinatorial background from signal itself and universality of the algorithms used for jets reconstruction and energy calibration at the wide range of energy/mass scales. Equivalently important aspect of this study is to verify applicability of the fast detector simulation, based on parametrisation of main features of the detector, for studying signal and background rates for the above channels. For that reason the detailed comparisons of the expected efficiencies and acceptances in full (based on Geant 3) and fast simulations are shown at the different stages of the selection procedures. In general good agreement is found between results obtained in both approaches.

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Thermostatistical properties of symmetric and asymmetric nuclear matter are studied in the framework of the relativistic mean field theory at a finite temperature. The statistical description via the grandcanonical potential produces an equation of state, which describes the nuclear liquid-gas phase transition as first order. The transition occurs at an excitation energy of 15–16 MeV per nucleon, and a density of 0.3–0.4 symmetric matter saturation density. This result is in accordance with the results of experimental observations of fragment distributions in heavy-ion collisions.

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We analyze the semileptonic weak decays of the octet baryons in a model independent approach, based on the algebraic structure of the Chiral Quark-Soliton Model. We argue that this analysis is in fact more general than the model itself. While the symmetry breaking for the semileptonic decays themselves is not strong, other quantities like \(\Delta s\) and \(\Delta {\mit \Sigma }\) are much more affected. We calculate \(\Delta {\mit \Sigma }\) and \(\Delta q\) for all octet baryons. Unfortunately, large experimental errors of \({\mit \Xi }^-\) decays propagate in our analysis, in particular, in the case of \(\Delta {\mit \Sigma } \) and \(\Delta s\). Only if the errors for these decays are reduced, the accurate theoretical predictions for \(\Delta {\mit \Sigma }\) and \(\Delta s\) will be possible.

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We present results on the event-by-event analysis of multiplicity and transverse momentum fluctuations for Au + Au collisions at RHIC energies. This analysis is based on Monte Carlo events obtained from HIJING and VENUS generators. The dependence of the results on centrality and energy of the collision as well as on the acceptance cuts is discussed. We found that the results obtained for the Monte Carlo generated events strongly depend on these parameters and disagree with a thermal model predictions. In a wide range of energies and centralities of the collisions the HIJING model predictions are different than those obtained from VENUS simulations.

abstract

Radioactive beams obtained by fragmentation reactions at relativistic energies provide new possibilities for \(\gamma \)-spectroscopy. Decay studies after implantation as well as in-beam single step Coulomb excitation and secondary fragmentation are commonly employed techniques. Isotopes of interest can be selected by particle tracking providing event-by-event \(Z\) and \(A\) determination. Beam intensities as low as 0.01 ions/s are sufficient to observe discrete \(\gamma \)-transitions using high resolution Ge-arrays and/or 4\(\pi \) scintillator-arrays. Severe background, in particular from Bremsstrahlung and large Doppler effects result from the high beam velocities of \(v\)/\(c\leq 60\,\%\). On the other hand, thick targets compensating limited beam intensities are an advantage of the high beam energies. Unknown regions of the nuclidic chart become available for detailed spectroscopy for the first time.