Static quark potential according to the dual-superconductor picture of QCD

We use the effective action describing long-range QCD, which predicts that QCD behaves as a dual superconductor, to derive the interaction energy between two heavy quarks as a function of separation. The dual-superconductor field equations are solved in an approximation in which the boundary between the superconducting vacuum and the region of normal vacuum surrounding the quarks is sharp. Further, non-Abelian effects are neglected. The resulting heavy-quark potential is linear in separation at large separation, and Coulomb-like at small separation. Overall it agrees very well with phenomenologically determined potentials

Quantized electric-flux-tube solutions to Yang-Mills theory

We suggest that long-distance Yang-Mills theory is more conveniently described in terms of electric rather than the customary magnetic vector potentials. On this basis we propose as an effective Lagrangian for this regime the most simple gauge-invariant (under the magnetic rather than electric gauge group) and Lorentz-invariant Lagrangian which yields a 1/q^4 gluon propagator in the Abelian limit. The resulting classical equations of motion have solutions corresponding to tubes of color electric flux quantized in units of e/2 (e is the Yang-Mills coupling constant). To exponential accuracy the electric color energy is contained in a cylinder of finite radius, showing that continuum Yang-Mills theory has excitations which are confined tubes of color electric flux. This is the criterion for electric confinement of color

A Constituent Quark Anti-Quark Effective Lagrangian Based on the Dual Superconducting Model of Long Distance QCD

We review the assumptions leading to the description of long distance QCD by a Lagrangian density expressed in terms of dual potentials. We find the color field distribution surrounding a quark anti-quark pair to first order in their velocities. Using these distributions we eliminate the dual potentials from the Lagrangian density and obtain an effective interaction Lagrangian $L_I ( \vec x_1 \, , \vec x_2 \, ; \vec v_1 \, , \vec v_2 )$ depending only upon the quark and anti-quark coordinates and velocities, valid to second order in their velocities. We propose $L_I$ as the Lagrangian describing the long distance interaction between constituent quarks. Elsewhere we have determined the two free parameters in $L_I$, $\alpha_s$ and the string tension $\sigma$, by fitting the 17 known levels of $b \bar b$ and $c \bar c$ systems. Here we use $L_I$ at the classical level to calculate the leading Regge trajectory. We obtain a trajectory which becomes linear at large $M^2$ with a slope $\alpha' \simeq .74 \, \hbox{GeV}^{-1}$, and for small $M^2$ the trajectory bends so that there are no tachyons. For a constituent quark mass between 100 and 150 MeV this trajectory passes through the two known Regge recurrences of the $\pi$ meson. In this paper, for simplicity of presentation, we have treated the quarks as spin-zero particles.Comment: {\bf 32,UW/PT94-0

Chiral-symmetry breaking in dual QCD

In the context of the formulation of QCD with dual potentials, we show that chiral-symmetry breaking occurs only in the confined state. Therefore, the transition temperature, beyond which chiral symmetry is restored, is the same as the deconfinement temperature. To carry out the calculation, it is necessary to couple quarks to dual gluons. We indicate how this is done (to lowest order in the magnetic coupling constant) and give the Feynman rules for quark–dual-gluon vertices

Interaction between solitons in gauge theories

A systematic method for obtaining asymptotic multisoliton solutions in gauge theories is given. These solutions are used to investigate the interaction between vortex lines in type-I and type-II superconductors, reproducing the known behavior. The application to QCD flux tubes and glueballs obtained from the long-range effective Lagrangian yield the following results: (1) No long-range Van der Waals–type forces exist between these solitons in spite of the fact that the Abelian force law obtained from this model is a linear potential; (2) the interactions between flux tubes and between flux tubes and anti-flux-tubes are identical, being repulsive at long range and strongly attractive at short range. This behavior differs sharply from the superconductor case, and results from the differences between the gauge groups SU(2) and U(1)

Centrifuge mounted motion simulator Patent

Centrifuge mounted motion simulator with elevator mechanis

"Oxide-free" tip for scanning tunneling microscopy

We report a new tip for scanning tunneling microscopy and a tip repair procedure that allows one to reproducibly obtain atomic images of highly oriented pyrolytic graphite with previously inoperable tips. The tips are shown to be relatively oxide-free and highly resistant to oxidation. The tips are fabricated with graphite by two distinct methods

Two-dimensional magnetism in the pnictide superconductor parent material SrFeAsF probed by muon-spin relaxation

We report muon-spin relaxation measurements on SrFeAsF, which is the parent compound of a newly discovered iron-arsenic-fluoride based series of superconducting materials. We find that this material has very similar magnetic properties to LaFeAsO, such as separated magnetic and structural transitions (TN = 120 K, Ts = 175 K), contrasting with SrFe2As2 where they are coincident. The muon oscillation frequencies fall away very sharply at TN, which suggests that the magnetic exchange between the layers is weaker than in comparable oxypnictide compounds. This is consistent with our specific heat measurements, which find that the entropy change S = 0.05 J/mol/K largely occurs at the structural transition and there is no anomaly at TN.Comment: 4 pages, 3 figure