���Ѧ� Interaction Leading to N* and ��* Resonances

We have performed a calculation for the three-body ????? system by using the fixed center approximation to Faddeev equations, taking the interaction between ?? and ??, ?? and ??, and ?? and ?? from the chiral unitary approach. We find several peaks in the modulus squared of the three-body scattering amplitude, indicating the existence of resonances, which can be associated to known I?=?1/2, 3/2 and J ^P ?=?1/2⁺, 3/2⁺ and 5/2⁺ baryon states.     

Scalar mesons moving in a finite volume and the role of partial wave mixing

Phase shifts and resonance parameters can be obtained from finite-volume lattice spectra for interacting pairs of particles, moving with non-zero total momentum. We present a simple derivation of the method that is subsequently applied to obtain the ?Ц? and ??K phase shifts in the sectors with total isospin I = 0 and I = 1/2 , respectively. Considering different total momenta, one obtains extra data points for a given volume that allow for a very efficient extraction of the resonance parameters in the infinite-volume limit. Corrections due to the mixing of partial waves are provided. We expect that our results will help to optimize the strategies in lattice simulations, which aim at an accurate determination of the scattering and resonance properties.     

Viscosity of the QGP from a virial expansion

In this work we calculate the shear viscosity ?? in the quark-gluon plasma within a virial expansion approach with particular interest in the ratio of ?? to the entropy density s, i.e. ??/s. We derive a realistic equation of state using a virial expansion approach which allows us to include the interactions between the partons in the deconfined phase. From the interaction we directly extract the effective coupling ?? _V for the determination of ??. Our results for ??/s show a minimum near to T _c very close with the lowest bound and, furthermore, in line with the experimental point from RHIC as well as with the lattice calculations.     

Induced photon emission from quark jets in ultrarelativistic heavy-ion collisions

We study the induced photon bremsstrahlung from a fast quark produced in AA collisions due to multiple scattering in quark-gluon plasma. For RHIC and LHC conditions, the induced photon spectrum is sharply peaked at a photon energy close to the initial quark energy. In this region, the contribution of the induced radiation to the photon fragmentation function exceeds the ordinary vacuum radiation. Contrary to previous analyses [4–7], our results show that, at RHIC and LHC energies, the final-state interaction effects in quark-gluon plasma do not suppress the direct photon production and may even enhance it at p _T ～5–15 GeV.     

Coherent photo- and lepto-production of vector mesons from deuterium

We discuss the coherent photo- and lepto-production of vector mesons from deuterium at intermediate (virtual) photon energies, 3 GeV ≲ ν ≲ 30 GeV. These processes provide several options to explore the space-time evolution of small size quark-gluon configurations. Furthermore, we study the dependence of the production cross section on the energy and momentum transfer t due to variations of the finite longitudinal interaction length. Kinematic regions are determined where the production cross section is most sensitive to the final state interaction of the initially produced hadronic wave packet. For unpolarized deuteron targets this double scattering contribution can be investigated mainly at large values of the momentum transfer t. For polarized targets kinematic windows sensitive to double scattering are available also at moderate t. We suggest several methods for an investigation of color coherence effects at intermediate energies.     

Troubles with the Proton rms-Radius

Due to the peculiar shape of the proton charge density ??(r) the value of the rms-radius r _rms determined from electron scattering data depends strongly on the density ??(r) at large radii, which is not fixed by scattering data. Supplementing the data with the large-r shape of ??(r) resulting from the Fock components (n?+???, . . .) dominating the large-r behavior produces a more reliable value. This radius agrees with the one we previously extracted, but disagrees with the one recently obtained from muonic Hydrogen. The origin of the discrepancy is not understood.     

Role of dipole image forces in molecular adsorption

The transverse-field XY model in one dimension is a well-known spin model for which the ground state properties and excitation spectrum are known exactly. The model has an interesting phase diagram describing quantum phase transitions (QPTs) belonging to two different universality classes. These are the transverse-field Ising model and the XX model universality classes with both the models being special cases of the transverse-field XY model. In recent years, quantities related to quantum information theoretic measures like entanglement, quantum discord (QD) and fidelity have been shown to provide signatures of QPTs. Another interesting issue is that of decoherence to which a quantum system is subjected due to its interaction, represented by a quantum channel, with an environment. In this paper, we determine the dynamics of different types of correlations present in a quantum system, namely, the mutual information I(?? _AB ), the classical correlations C(?? _AB ) and the quantum correlations Q(?? _AB ), as measured by the quantum discord, in a two-qubit state. The density matrix of this state is given by the nearest-neighbour reduced density matrix obtained from the ground state of the transverse-field XY model in 1d. We assume Markovian dynamics for the time-evolution due to system-environment interactions. The quantum channels considered include the bit-flip, bit-phase-flip and phase-flip channels. Two different types of dynamics are identified for the channels in one of which the quantum correlations are greater in magnitude than the classical correlations in a finite time interval. The origins of the different types of dynamics are further explained. For the different channels, appropriate quantities associated with the dynamics of the correlations are identified which provide signatures of QPTs. We also report results for further-neighbour two-qubit states and finite temperatures.     

Messung der Wirkungsquerschnitte für elastische Elektronenstreuung in polykristallinen Al-Schichten bei verschiedenen Temperaturen

Absolute intensities of electrons scattered elastically in a polycrystalline aluminium foil were measured by means of a retarding field apparatus at 51 kev and in the temperature range 150–800 °K. From the integrated intensities of the Debye-Scherrer rings (I _R), of the temperature diffuse scattering (I _TDS) and of the temperature independent diffuse scattering (I _DS) the total cross sections σ of the foil for the corresponding scattering processes have been determined. The measured values σ _R (T) for Laue-Bragg scattering show very good agreement with the calculation, based on the dynamical two beam approximation, and σ _TDS (T) for the temperature diffuse scattering agrees fairly well with the kinematical value for the Einstein model of the vibrating crystal. The temperature independent part of the elastic background intensity is mainly due to elastic scattering of electrons in the amorphous oxide layer of the aluminium foil. It turns out, that the sum of all cross sections for the elastic scattering processes mentioned increases slightly with temperature.     

Nucleation rate of the quark-gluon plasma droplet at finite quark chemical potential

The nucleation rate of quark-gluon plasma (QGP) droplet is computed at finite quark chemical potential. In the course of computing the nucleation rate, the finite size effects of the QGP droplet are taken into account. We consider the phenomenological flow parameter of quarks and gluons, which is dependent on quark chemical potential and we calculate the nucleation rate of the QGP droplet with this parameter. While calculating the nucleation rate, we find that for low values of quark phenomenological parameter ?? _q , nucleation rate is negligible and when ?? _q increases, nucleation rate increases significantly.     

Mechanism of pion production in αp scattering at 1 GeV/nucleon

An analysis of the experimental data on one-pion and two-pion production in the p(??, ????)X reaction studied in a semi-exclusive experiment at an energy of E _?? = 4.2 GeV has been performed. The obtained results demonstrate that the inelastic ??-particle scattering on the proton at the energy of the experiment proceeds either through excitation and decay of the ?? resonance in the projectile ?? particle, or through excitation in the target proton of the Roper resonance, which decays into a nucleon and a pion, or a nucleon and a ?? meson??a system of two pions in the isospin I = 0, S-wave state.     

Bag-model quantum chromodynamics at low energy

Gluon-exchange mediating quark-exchange scattering is the mechanism of lowest order in perturbative QCD that contributes to the strong interactions at low energy. When it is dressed with long-range quark-gluon correlations by means of bag-model wavefunctions, this quark interchange force becomes bilocal in the quark-gluon sector involving the whole bag and non-perturbative. When it is Fierz-rearranged, the quark-interchange amplitude takes on the usual local form for each hadron that is expected from the wealth of empirical knowledge at low energy. This quark interchange is calculated here in the MIT bag model, which is supplemented by tunneling rules, and then applied to elastic NN scattering, and subsequently toπN andππ scattering. For each reaction the OBE interaction is obtained in agreement with meson theoretic models. Repulsive axial-vector meson exchanges are predicted for NN scattering at short range. The chiral structure of the quark interchange force in conjunction with its tunneling aspects suggest an interpretation of the strong interactions at low energy as Josephson currents of non-Abelian superconductivity.     

Projected shell model study of yrast bands in even-even 100–118Pd isotopes

The projected shell model (PSM) study of ^100?C118Pd nuclei is carried out. The reliability of the ground-state wave functions is checked by reproducing yrast spectra and electromagnetic properties. The results of calculations indicate that the observed deformation systematics in ^100?C118Pd isotopes depends on the increase of occupation probability of (1h _{11/2 ??} ) orbit and the deformation producing tendency of n-p interaction operating between Spin Orbit Partner (SOP) orbits (d _5/2)_???(d _3/2) _?? and (g _9/2)_???(g _7/2) _?? . Beside this, the results on band diagrams show that the yrast spectra in Pd isotopes do not arise from a single intrinsic state only but also from multi-quasiparticle states.     

Glauber Dynamics for the Mean-Field Potts Model

We study Glauber dynamics for the mean-field (Curie-Weiss) Potts model with q??3 states and show that it undergoes a critical slowdown at an inverse-temperature ?? _s (q) strictly lower than the critical ?? _c (q) for uniqueness of the thermodynamic limit. The dynamical critical ?? _s (q) is the spinodal point marking the onset of metastability. We prove that when ??<?? _s (q) the mixing time is asymptotically C(??,q)nlogn and the dynamics exhibits the cutoff phenomena, a sharp transition in mixing, with a window of order n. At ??=?? _s (q) the dynamics no longer exhibits cutoff and its mixing obeys a power-law of order n ^4/3. For ??>?? _s (q) the mixing time is exponentially large in n. Furthermore, as ?????? _s with n, the mixing time interpolates smoothly from subcritical to critical behavior, with the latter reached at a scaling window of O(n ^?2/3) around ?? _s . These results form the first complete analysis of mixing around the critical dynamical temperature??including the critical power law??for a model with a first order phase transition.     

Probability distribution of singly and multiply scattered light near the critical point of a binary mixture

The probability density function p(I) is theoretically and experimentally investigated in the case of single, double, and multiple light scattering near a second-order transition (demixing of the binary mixture nitrobenzene and n-hexane). Experimentally we find no differences between the statistics of singly, doubly or multiply scattered light, and as expected from theory, p(I) shows an exponential variation. These results justify the use of either heterodyne or homodyne techniques for studying single or multiple scattering close to a critical point. We also describe a particularly simple way of determining whether homodyne or heterodyne detection occurs.     

Laser fluctuation studies in intensity dependent absorption of light

The interaction of a laser with an intensity-dependent absorber has been analysed for discrete regions of operations of the laser. It is shown that the beam is thermally defocused due to absorption for the values of intensity under consideration. The fluctuation properties have been analysed by evaluating 〈I〉,〈I ²〉 and 〈(ΔI)²〉/〈I〉².     

Isotope-selective ionization utilizing molecular alignment and non-resonant multiphoton ionization

We demonstrate laser nitrogen isotope separation, which is based on field-free alignment and angular-dependent ionization of ¹⁴N₂ and ¹⁵N₂ isotopologues. A linearly polarized short laser pulse (???~?795?nm, ?????~?60?fs) creates rotational wave packets in the isotopologues, which periodically revive with different revival times as a result of different moments of inertia. Another linearly polarized short laser pulse (???~?795?nm, ?????~?60?fs) ionizes one of the isotopologues selectively as a result of their different angular distributions. In the present experiments, the ion yield ratio R [=I(¹⁵N₂ ⁺)/I(¹⁴N₂ ⁺)] can be changed in the range from 0.85 to 1.22, depending on the time delay between the two laser pulses.     

Yangian algebra in the bi-qubit system and mixed light pseudoscalar meson state

We extend the holographic Ricci dark energy model to include some direct, non-gravitational interaction between dark energy and dark matter. We consider three phenomenological forms for the interaction term Q in the model, namely, Q is taken proportional to the Hubble expansion rate and the energy densities of dark sectors (taken to be ?? _de, ?? _m, and ?? _de+?? _m, respectively). We obtain a uniform analytical solution to the three interacting models. Furthermore, we constrain the models by using the latest observational data, including the 557 Union2 type Ia supernovae data, the cosmic microwave background anisotropy data from the 7-yr WMAP, and the baryon acoustic oscillation data from the SDSS. We show that in the interacting models of the holographic Ricci dark energy, a more reasonable value of ?? _m0 will be obtained, and the observations favor a rather strong coupling between dark energy and dark matter.     

Linear and nonlinear liftings of states of quantum systems

In this paper, we study the representability of an arbitrary quantum state ?? ?? ??(H) as the reduction of a vector state r ?? ??(H) of the extended system. We extend the operation of lifting from the set of states ?? _n (H) to the set of generalized states ??(H). A method of constructing the Hilbert space H and the affine linear lifting ??(H) ?? ??(H) is studied. The construction of individual expansion H _?? of the space H for which the state ?? is a reduction of a vector state H _?? is of special interest.