Dynamical Confinement Research Articles

Can One Hear Whistler Waves?

The aim of this article is to propose a mathematical framework giving access to a better understanding of whistler-mode chorus emissions in space plasmas. There is presently a general agreement that the emissions of whistler waves involve a mechanism of wave-particle interaction which can be described in the framework of the relativistic Vlasov-Maxwell equations. In dimensionless variables, these equationsinvolve a penalized skew-symmetric term where the inhomogeneity of the strong exterior magnetic field plays an essential part. The description of the related phenomena is achieved in two stages. The first is based on a new approach allowing to extend in longer times the classical insights on fast rotating fluids; it justifies the existence and the validity of long time gyro-kinetic equations; it furnishes criterions to impose on a magnetic field in order to obtain the long time dynamical confinement of plasmas. The second stage is based on a study of oscillatory integrals implying special phases; it deals with the problem of the creation of light inside plasmas.

A dynamical mass and confinement in nucleon model

A possible dynamical softening of the Chiral bag is studied in connection with the chiral quark model and the Nambu–Jona–Lasinio (NJL) model. It is demonstrated that the bag functions constructed by the pion degrees is able to confine quark through generation of the rising effective mass of valence quark due to the pion dressing and break chiral symmetry dynamically. The tendency of the bag functions toward the MIT bag is illustrated in the large-n limit for a solitonic configuration of the chiral field Un(r) for which U1(r) is the Skyrmion profile. The mass running with the length scale agrees with that of the NJL Model for n ≥ 2.

Dynamical Masses and Confinement in Graphene

Dynamical Mass Generation and Confinement are non-perturbative phenomena with large impact on the study of hadron and condensed matter physics. We study these phenomena in the light of the Schwinger-Dyson equations in various field theories, like Quantum Electrodynamics (QED) and Quantum Electrodynamics in the plane (QED3). Our aim is to describe the impact of these phenomena for the semi-metal–insulator transition in graphene, which is modeled by a peculiar field theory that inherits properties of both QED and QED3.

Chiral symmetry breaking and confinement beyond rainbow-ladder truncation

A non-perturbative construction of the 3-point fermion-boson vertex which obeys its Ward-Takahashi or Slavnov-Taylor identity, ensures the massless fermion and boson propagators transform according to their local gauge covariance relations, reproduces perturbation theory in the weak coupling regime and provides a gauge independent description for dynamical chiral symmetry breaking (DCSB) and confinement has been a long-standing goal in physically relevant gauge theories such as quantum electrodynamics (QED) and quantum chromodynamics (QCD). In this paper, we demonstrate that the same simple and practical form of the vertex can achieve these objectives not only in 4-dimensional quenched QED (qQED4) but also in its 3-dimensional counterpart (qQED3). Employing this convenient form of the vertex \emph{ansatz} into the Schwinger-Dyson equation (SDE) for the fermion propagator, we observe that it renders the critical coupling in qQED4 markedly gauge independent in contrast with the bare vertex and improves on the well-known Curtis-Pennington construction. Furthermore, our proposal yields gauge independent order parameters for confinement and DCSB in qQED3.

Dynamical Mass Generation and Confinement in Maxwell-Chern-Simons Planar Quantum Electrodynamics

We study the non-perturbative phenomena of Dynamical Mass Generation and Confinement by truncating at the non-perturbative level the Schwinger-Dyson equations in Maxwell-Chern-Simons planar quantum electrodynamics. We obtain numerical solutions for the fermion propagator in Landau gauge within the so-called rainbow approximation. A comparison with the ordinary theory without the Chern-Simons term is presented.

Dynamical nuclear polarization and confinement effects in ZnO quantum dots

AbstractThe spatial distribution of the electronic wave function of a shallow donor (SD) in a ZnO semiconductor quantum dots (QD's) has been determined in the regime of quantum confinement by using the nuclear spins as probes. Hyperfine (HF) interactions as monitored by electron nuclear double resonance spectroscopy quantitatively reveal the transition from semiconductor to molecular properties upon reduction of the size of the nanoparticles. Influence of confinement effect on g‐factor value of SD's in ZnO and CdS QD's was displayed. The almost complete dynamic nuclear polarization (DNP) of nuclear spins has been demonstrated can be achieved in ZnO QD's by saturating the EPR transition of the SD present in the QD's with using high‐frequency at low temperatures. Polarization of 67Zn nuclear spins in ZnO core and of 1H nuclear spins in the Zn(OH)2 capping layer have been obtained which manifests itself via the creation of a hole and an antihole in the EPR absorption line of the SD in QD's and a shift of the hole (antihole). The enhancement of the nuclear polarization opens the possibility to study semiconductor nanostructures with NMR techniques

Band-gap-confinement and image-state-recapture effects in the survival of anions scattered from metal surfaces

The resonant charge transfer process in the collision of hydrogen anions with metal surfaces is described within a single-active-electron wave-packet propagation method. The ion-survival probability is found to be strongly enhanced at two different surface-specific perpendicular velocities of the ion. It is shown that, while the low-velocity enhancement is induced from a dynamical confinement of the ion level inside the band gap, the high-velocity enhancement is due to electron recapture from transiently populated image states. Results are presented for Li(110), Cu(111), and Pd(111) surfaces.

Quantum electrodynamics in three dimensions: Dynamical chiral symmetry breaking, confinement, and disorder effects

We study dynamical chiral symmetry breaking (DCSB), confinement, and disorder effects in $(2+1)$-dimensional quantum electrodynamics (QED) of massless fermion $\ensuremath{\psi}$ and scalar boson $\ensuremath{\phi}$. It is found that gauge symmetry breaking (GSB) induced by nonzero $⟨\ensuremath{\phi}⟩$ rapidly suppresses the occurrence of DCSB, and certain disorders tend to enhance it. While DCSB leads to confinement in the gauge symmetric state, the matter fields are always deconfined in the GSB state whether chiral symmetry is broken or not. According to the symmetries and the classical potential between particles, ${\text{QED}}_{3}$ has three possible phases, which exhibit distinct phenomena and can be identified by appropriate observable quantities.

The quark–gluon vertex in Landau gauge QCD: Its role in dynamical chiral symmetry breaking and quark confinement

The infrared behavior of the quark–gluon vertex of quenched Landau gauge QCD is studied by analyzing its Dyson–Schwinger equation. Building on previously obtained results for Green functions in the Yang–Mills sector, we analytically derive the existence of power-law infrared singularities for this vertex. We establish that dynamical chiral symmetry breaking leads to the self-consistent generation of components of the quark–gluon vertex forbidden when chiral symmetry is forced to stay in the Wigner–Weyl mode. In the latter case the running strong coupling assumes an infrared fixed point. If chiral symmetry is broken, either dynamically or explicitly, the running coupling is infrared divergent. Based on a truncation for the quark–gluon vertex Dyson–Schwinger equation which respects the analytically determined infrared behavior, numerical results for the coupled system of the quark propagator and vertex Dyson–Schwinger equation are presented. The resulting quark mass function as well as the vertex function show only a very weak dependence on the current quark mass in the deep infrared. From this we infer by an analysis of the quark–quark scattering kernel a linearly rising quark potential with an almost mass independent string tension in the case of broken chiral symmetry. Enforcing chiral symmetry does lead to a Coulomb type potential. Therefore, we conclude that chiral symmetry breaking and confinement are closely related. Furthermore, we discuss aspects of confinement as the absence of long-range van der Waals forces and Casimir scaling. An examination of experimental data for quarkonia provides further evidence for the viability of the presented mechanism for quark confinement in the Landau gauge.

Chiral symmetry breaking and stability of strangelets

We discuss the stability of strangelets by considering dynamical chiral symmetry breaking and confinement. We use a $U(3{)}_{L}\ifmmode\times\else\texttimes\fi{}U(3{)}_{R}$ symmetric Nambu-Jona-Lasinio (NJL) model for chiral symmetry breaking supplemented by a boundary condition for confinement. It is shown that strangelets (finite number of strange quarks) with baryon number $A\ensuremath{\lesssim}{10}^{3}$ is the lowest quark droplets. For the observables, we obtain the masses and the charge-to-baryon number ratios of the strangelets. These quantities are compared with the observed data of the exotic particles.

Deconfining transition in Full QCD

We present evidence that in full QCD with two dynamical quarks confinement is produced by dual superconductivity of the vacuum as in the quenched theory. Preliminary information is obtained on the nature of the deconfining transition.

Large-scale dynamics in turbulent mixing and the three-dimensional space–time behaviour of outer fluid interfaces

Experiments have been conducted to investigate turbulent mixing and the dynamics of outer fluid interfaces, i.e. the interfaces between mixed fluid and pure ambient fluid. A novel six-foot-diameter octagonal-tank flow facility was developed to enable the optical imaging of fluid interfaces above the mixing transition, corresponding to fully developed turbulence. Approximately 10003 whole-field three-dimensional space– time measurements of the concentration field were recorded using laser-induced- fluorescence digital-imaging techniques in turbulent jets at a Reynolds number of Re ∼ 20 000, Schmidt number of Sc ∼ 2000, and downstream distance of ∼ 500 nozzle diameters. Multiple large-scale regions of spatially nearly uniform-concentration fluid are evident in instantaneous visualizations, in agreement with previous findings above the mixing transition. The ensemble-averaged probability density function of concentration is found to exhibit linear dependence over a wide range of concentration thresholds. This can be accounted for in terms of the dynamics of large-scale well- mixed regions. Visualization of the three-dimensional space–time concentration field indicates that molecular mixing of entrained pure ambient fluid is dynamically initiated and accomplished in the vicinity of the unsteady large scales. Examination of the outer interfaces shows that they are dynamically confined primarily near the instantaneous large-scale boundaries of the flow. This behaviour is quantified in terms of the probability density of the location of the outer interfaces relative to the flow centreline and the probability of pure ambient fluid as a function of distance from the centreline. The current measurements show that the dynamics of outer interfaces above the mixing transition is significantly different from the behaviour below the transition, where previous studies have shown that unmixed ambient fluid can extend across a wide range of transverse locations in the flow interior. The present observations of dynamical confinement of the outer interfaces to the unsteady large scales, and considerations of entrainment, suggest that the mechanism responsible for this behaviour must be the coupling of large-scale flow dynamics with the presence of small-scale structures internal to the large-scale structures, above the mixing transition. The dynamics and structure of the outer interfaces across the entire range of space–time scales are quantified in terms of a distribution of generalized level-crossing scales. The outer-interface behaviour determines the mixing efficiency of the flow, i.e. fraction of mixed fluid. The present findings indicate that the large-scale dynamics of the outer interfaces above the mixing transition provides the dominant contribution to the mixing efficiency. This suggests a new way to quantify the mixing efficiency of turbulent flows at high Reynolds numbers.

Dynamical symmetry breaking, confinement with flat-bottom potential

In this Letter, we calculate the dressed quark propagator with the flat bottom potential in the framework of the rainbow Schwinger–Dyson equation. Then based on the nonperturbative dressed quark propagator, we calculate the π decay constant and the quark condensate. The π decay constant is an important parameter in describing the interplay between dynamical symmetry breaking and confinement, while the quark condensate is an order parameter for dynamical chiral symmetry breaking. To implement confinement, we prove that the dressed quark propagator has no poles on the real timelike p 2 axial, the absence of Kallen–Lehmann spectral representation obviously precludes the existence of free quarks.

N∗ electroproduction amplitudes in a model with dynamical confinement

The Roper resonance is described in a chiral version of the chromodielectric model as a cluster of three quarks in radial-orbital configuration (1s)$^2$(2s)$^1$, surrounded by $\pi$ and $\sigma$-meson clouds and by a chromodielectric field which assures quark dynamical confinement. Radial profiles for all fields are determined self-consistently for each baryon. Transverse $A_{1/2}$ and scalar $S_{1/2}$ helicity amplitudes for the nucleon-Roper transition are calculated. The contribution of glueball and $\sigma$-meson vibrations is estimated; although small for N(1440), the $\sigma$ contribution can be large for N(1710).

Quark number susceptibilities, strangeness, and dynamical confinement

We report first results on the strange quark number susceptibility, chi_s, over a large range of temperatures, mainly in the plasma phase of QCD. Chi_s jumps across the phase transition temperature, T_c, and grows rapidly with temperature above but close to T_c. For all quark masses and susceptibilities in the entire temperature range studied, we found significant departures from ideal-gas values. We also observed a strong correlation between these quantities and the susceptibility in the scalar/pseudo-scalar channel, supporting ideas of ``dynamical confinement'' in the high temperature phase of the QCD plasma.

FINITE T MESON CORRELATIONS AND QUARK DECONFINEMENT

The finite temperature spatial [Formula: see text] correlation modes in the π and ρ channels are studied with the rainbow-ladder truncated quark Dyson–Schwinger equation and Bethe–Salpeter equation in the Matsubara formalism. To retain the finite range of the effective interaction while facilitating summation over fermion Matsubara modes necessary to ensure continuity at T=0, a separable kernel is used. The model is fixed by T=0 properties and it implements dynamical chiral symmetry breaking and quark confinement. Transition temperatures for deconfinement (Td) and chiral restoration (Tc) are identified. Above and below these transitions we study Mπ(T), fπ(T) and the three-space transverse and longitudinal masses [Formula: see text] and [Formula: see text]. We also study the intrinsic T-dependence of the electromagnetic coupling constant gρ(T) and the strong coupling constant gρππ(T). For both this model and a related semi-analyticinfrared dominant model, we analyze the high T behavior of the obtained masses in comparison to the M(T)→2πT behavior found in lattice QCD simulations.

Strange hadrons from quarkand hadron matter: a comparison

In a simplified model we study the hadronization of quark matter in anexpanding fireball, in particular the approach to a final hadroniccomposition in equilibrium. Ideal hadron gas equilibrium constrained byconservation laws, the fugacity parametrization, as well as linear andnonlinear coalescence approaches are recognized as differentapproximations to this in-medium quark fusion process. It is shown thatcolour confinement requires a dependence of the hadronization crosssection on quark density in the presence of flow (dynamical confinement).

The chromodielectric soliton model: quark self-energy and hadron bags

The chromodielectric soliton model is Lorentz and chirally invariant. It has been demonstrated to exhibit dynamical chiral symmetry breaking and spatial confinement in the locally uniform approximation. We here study the full nonlocal quark self-energy in a color-dielectric medium modeled by a two-parameter Fermi function. Here color confinement is manifest. The self-energy thus obtained is used to calculate quark wave functions in the medium which, in turn, are used to calculate the nucleon and pion masses in the one-gluon-exchange approximation. The nucleon mass is fixed to its empirical value using scaling arguments; the pion mass (for massless current quarks) turns out to be small but nonzero, depending on the model parameters.

Meson transition form factors from a QCD model field theory

We discuss form factors and coupling constants for the γ ∗π 0γ , ϱππ and γπϱ interactions generated by a model field theory that produces finite size qq meson modes. The approach implements dressing of the vertices and propagators consistent with dynamical chiral symmetry breaking, gauge invariance, quark confinement and perturbative QCD.

The off-shell axial anomaly via the [formula omitted] transition

The γ ∗π 0 → γ form factor, including the extension off the pion mass-shell, is obtained from a generalized impulse approximation within a QCD-based model field theory known to provide an excellent description of the pion charge form factor. This approach implements dressing of the vertices and propagators consistent with dynamical chiral symmetry breaking, gauge invariance, quark confinement and perturbative QCD. Nonperturbative behavior at the real photon vertex is found to generate a logarithmic correction to the large spacelike- q 2 behavior.