Multi-jet event rates in deep inelastic scattering and determination of the strong coupling constant

Jet event rates in deep inelastic ep scattering at HERA are investigated applying the modified JADE jet algorithm. The data are corrected for detector and hadronization effects and then compared with perturbative QCD predictions using next-to-leading order calculations. The strong coupling constant is determined evaluating the jet event rates. Values of are extracted in four different bins of the negative squared momentum transfer in the range from 40 GeV to 4000 GeV. A combined fit of the renormalization group equation to these several values results in     

Nuclear spin response to inelastic proton scattering: Finite geometry and absorption effects

Recent experiments have clearly demonstrated the ability of inelastic proton scattering to act as a precise probe of the nuclear spin response. Previous calculations based on infinite or semi-infinite matter models differ markedly from experiment in their prediction of longitudinal to transverse response function ratios. The present work indicates that finite geometry and absorption effects are crucial in bringing predictions closer to experiment. The effect of including isobar excitations is also investigated and assessed critically.     

Long range quantum effects in infra-red stable Yang-Mills systems

The large distance behaviour of perturbative non-Abelian gauge systems is analysed. Scale invariant interference effects are found in gauge invariant amplitudes due to a non-cancellation of Coulomb singularities.     

Strong coupling effects in the transport equation for deeply inelastic heavy-ion collisions

The appearance of strong coupling effects in the transport equation for deeply inelastic heavy-ion collisions is examined in the framework of a one-dimensional model. An analytical solution for the Greens function shows that in a deeply inelastic collision the system is in the strong-coupling regime for the bulk of the interaction. An analytical method is presented for evaluating the transport coefficients which can equally be applied to the three-dimensional case. The transport coefficients and cross sections are calculated and the dependence of the results on the parameters of the underlying random-matrix model is displayed.     

Iterative analysis of strong coupling effects in semiselective J spectroscopy

A computer program for the iterative analysis of semiselective J spectra (A. Bax, J. Magn. Reson.52, 330 (1983)) is described, and experimental and calculated f₁ cross sections through semiselective 2D J spectra for the three-spin system of fumaric acid monoethyl ester and the five-spin system of thiophene are compared.     

Electron phonon systems from weak to strong coupling

Electron and phonon spectra are derived for an electron-phonon system coupled by the Fröhlich interaction. We cover the range from small coupling <1 to large coupling 1 for a commensurate filling of the bare band. The evolution of the Migdal solution into a charge density wave and finally into a regular lattice of small polarons is studied.     

A three-soliton structure with strong and weak coupling in a wide-aperture laser with saturable absorption

A soliton complex consisting of three laser solitons is found with the help of numerical simulation of the spatiotemporal structure of the field in a wide-aperture class-A laser with saturable absorption in the mean field approximation with respect to the longitudinal coordinate. Two solitons are strongly coupled and rotate, whereas the third one is weakly coupled with this pair of solitons and revolves around it with a smaller angular velocity. A phase portrait of transverse energy fluxes of radiation that corroborates this type of coupling between the solitons is presented.     

Limit on right handed weak coupling parameters from inelastic neutrino interactions

Right handed weak quark currents coupled to the usual left handed weak lepton current would be seen in inclusive antineutrino scattering on nuclei as a contribution at largey with the quark (not antiquark) structure function. We do not see such a term, and can therefore put an upper limit on the relative strengths of such right handed currents: \(\varrho ^2 = \frac{{\sigma _R }}{{\sigma _L }}< 0.009\) , 90% confidence. This measurement puts limits on the mixing angle of left-right symmetric models. In distinction to similar limits derived from muon decay or β decay, our limits are also valid if the right handed neutrino is heavy.     

Wave motion and dispersion phenomena: veering, locking and strong coupling effects

The dispersion curves describe wave propagation in a structure, each branch representing a wave mode. As frequency varies the wavenumbers change and a number of dispersion phenomena may occur. This paper characterizes, analyzes, and quantifies these phenomena in general terms and illustrates them with examples. Two classes of phenomena occur. Weak coupling phenomena-veering and locking-arise when branches of the dispersion curves interact. These occur in the vicinity of the frequency at which, for undamped waveguides, the dispersion curves in the uncoupled waveguides would cross: if two dispersion curves (representing either propagating or evanescent waves) come close together as frequency increases then the curves either veer apart or lock together, forming a pair of attenuating oscillatory waves, which may later unlock into a pair of either propagating or evanescent waves. Which phenomenon occurs depends on the product of the gradients of the dispersion curves. The wave mode shapes which describe the deformation of the structure under the passage of a wave change rapidly around this critical frequency. These phenomena also occur in damped systems unless the levels of damping of the uncoupled waveguides are sufficiently different. Other phenomena can be attributed to strong coupling effects, where arbitrarily light stiffness or gyroscopic coupling changes the qualitative nature of the dispersion curves.     

Optical absorption by atomically doped carbon nanotubes under strong atom–field coupling

We analyze optical absorption by atomically doped carbon nanotubes with a special focus on the frequency range close to the atomic transition frequency. We derive the optical absorption line-shape function and, having analyzed particular achiral nanotubes of different diameters, predict the effect of absorption line splitting due to strong atom–vacuum–field coupling in small-diameter nanotubes.     

Parton saturation at strong coupling from AdS/CFT

I describe the parton picture at strong coupling emerging from the gauge/gravity duality, with emphasis on the universality of the phenomenon of parton saturation. I discuss several consequences of this picture for the phenomenology of a strongly coupled quark–gluon plasma, which are potentially relevant for heavy ion collisions at RHIC and LHC.     

Two-step spin conversion and other effects in the atom-phonon coupling model

We study an atom-phonon coupling model introduced recently for spin-conversion phenomenon. The originality of this model, performed on a linear chain of atoms, is that the elastic force constant values of the spring linking two atoms depends on their electronic states. This leads to introduce naturally in the chain long- and short-range interactions, which appear respectively like a Zeeman and an exchange interactions. The exchange-like interaction can be ferro-, antiferro- or equal to zero. The effects of long-range interactions have already been studied. Here we study those of the short-range interaction. Some parts of the chain phase diagram are analysed and the main features of the experimental behaviours of spin conversion compounds are qualitatively reproduced.Received: 2 February 2004, Published online: 29 June 2004PACS: 63.20.Kr Phonon-electron and phonon-phonon interactions - 63.50. + x Vibrational states in disordered systems - 64.60.-i General studies of phase transitions     

Long range correlations and hydrodynamic expansion

Nuclear collision experiments exhibit correlations peaked in relative azimuthal angle with a long range in rapidity. Called the ridge, this peak occurs both with and without a jet trigger. We argue that the energy and projectile-mass dependence of the ridge can be described by an early Glasma stage followed by hydrodynamic flow.     

Glueball spectroscopy from strong coupling expansions in hamiltonian lattice QCD

Masses of all the glueballs which are created by 6- or 7-link operators are calculated to order g^?8 in pure SU(3) hamiltonian lattice gauge theory. Several low-lying states are found with masses $\text{m(0}{}^{\mathrm{++1}}\text{)～ 1.4 m}{}_{\mathrm{<mtext>s</mtext>}}\text{, m(0}{}^{\mathrm{++7}}\text{) ～ 1.7 m}{}_{\mathrm{<mtext>s</mtext>}}$ (¹ and ⁷ stand for radial excitations and m_s is the mass of the lowest 0⁺⁺ state), . These values are obtained at the point g^?2 ? 0.8, which lies near the scaling region.