Null structure and local well-posedness in the energy class for the Yang-Mills equations in Lorenz gauge

We demonstrate null structure in the Yang-Mills equations in Lorenz gauge. Such structure was found in Coulomb gauge by Klainerman and Machedon, who used it to prove global well-posedness for finite-energy data. Compared with Coulomb gauge, Lorenz gauge has the advantage---shared with the temporal gauge---that it can be imposed globally in space even for large solutions. Using the null structure and bilinear space-time estimates, we also prove local-in-time well-posedness of the equations in Lorenz gauge, for data with finite energy. The time of existence depends on the initial energy and on the $H^s \times H^{s-1}$-norm of the initial potential, for some $s < 1$.Comment: Minor typos corrected, references update

Kugo-Ojima confinement criterion, Zwanziger-Gribov horizon condition, and infrared critical exponents in Landau gauge QCD

The Kugo-Ojima confinement criterion and its relation to the infrared behaviour of the gluon and ghost propagators in Landau gauge QCD are reviewed. The realization of this confinement criterion (which in Landau gauge relates to Zwanziger's horizon condition) results from quite general properties of the ghost Dyson-Schwinger equation. The numerical solutions for the gluon and ghost propagators obtained from a truncated set of Dyson-Schwinger equations provide an explicit example for the anticipated infrared behaviour. These results are in good agreement, also quantitatively, with corresponding lattice data obtained recently. The resulting running coupling approaches a fixed point in the infrared, $\alpha(0) = 8.9/N_c$. Solutions for the coupled system of Dyson-Schwinger equations for the quark, gluon and ghost propagators are presented. Dynamical generation of quark masses and thus spontaneous breaking of chiral symmetry is found. In the quenched approximation the quark propagator functions agree well with those of corresponding lattice calculations. For a small number of light flavours the quark, gluon and ghost propagators deviate only slightly from the quenched ones. While the positivity violation of the gluon spectral function is apparent in the gluon propagator, there are no clear indications of positivity violations in the Landau gauge quark propagator.Comment: 10 pages, 4 figures; invited talk presented by R. Alkofer at the International Conference Confinement V Gargnano, Italy, September 10-14, 200

ACES RED Experiment #1 Environmental Test Results for Industrial Grade, Non-traditional, and Other Components Lacking Flight Heritage

Results of the thermal vacuum chamber (TVAC) testing and vibrational testing of the ACES RED Experiment #1 are presented. Performance of commercial-off-the-shelf components such as the Avnet PicoZed, the Xiphos Q7, the MAI-400, and a NovaTel GNSS during TVAC testing are provided and analyzed. To our knowledge, this is the first orbital flight of this version of the GNSS, this version of the MAI-400, and the PicoZed. The experiment utilizes a novel structural concept for ease of electronics assembly and disassembly. The health monitoring system measures temperatures, vibration, voltages, and currents for situational awareness of each of these component\u27s relative performance. An assessment and progression of the technology readiness level of the hardware is also presented

Thermodynamic Properties of the Piecewise Uniform String

The thermodynamic free energy F is calculated for a gas whose particles are the quantum excitations of a piecewise uniform bosonic string. The string consists of two parts of length L_I and L_II, endowed with different tensions and mass densities, adjusted in such a way that the velocity of sound always equals the velocity of light. The explicit calculation is done under the restrictive condition that the tension ratio x = T_I/T_II approaches zero. Also, the length ratio s = L_II/L_I is assumed to be an integer. The expression for F is given on an integral form, in which s is present as a parameter. For large values of s, the Hagedorn temperature becomes proportional to the square root of s.Comment: 32 pages, latex, no figure

Additional Shear Wall Values for Light Weight Steel Framing (draft)

AlSI sponsored research at Santa Clara University (Serrette, 1996) led to the development of shear values for plywood, oriented strand board (OSB), and gypswn wallboard (GWB) sheathed light weight steel framed wall assemblies. The scope of the 1996 work was, however, limited to plywood, OSB. and GWB on 0.033 in. (20 gauge) framing. To provide a wider range of design options and clarify some of the values from the 1996 test program. a new test program was initialed. The new program included the following wall assemblies: flat strap X-braced walls. steel sheathed walls, high aspect ratio walls, and walls framed with 0.054 in. and 0.043 in. (16 gauge and 18 gauge, respectively} studs. As in the I 996 test program, the new assemblies were tested under static and cyclic loading. For each wall assembly configuration tested in the current program, the applied load, lateral displacement (at the top plate), slip, uplift, and mode of failure were monitored and recorded. Based on the test results, maximum loads (and corresponding displacements) were interpreted for design

Metric fluctuations and the Weak Equivalence Principle

We describe space--time fluctuations by means of small fluctuations of the metric on a given background metric. From a minimally coupled Klein--Gordon equation we obtain within a weak-field approximation up to second order and an averaging procedure over a finite space--time scale given by the quantum particle in the non--relativistic limit a modified Schr\"odinger equation. The dominant modification consists in an anomalous inertial mass tensor which depends on the type of particle and on the fluctuation scenario. The scenario considered in this paper is a most simple picture of spacetime fluctuations and gives an existence proof for an apparent violation of the weak equivalence principle and, in general, for a violation of Lorentz invariance.Comment: 10 pages, to appear in Class. Quantum Grav. (2008

Regularization of 2d supersymmetric Yang-Mills theory via non commutative geometry

The non commutative geometry is a possible framework to regularize Quantum Field Theory in a nonperturbative way. This idea is an extension of the lattice approximation by non commutativity that allows to preserve symmetries. The supersymmetric version is also studied and more precisely in the case of the Schwinger model on supersphere [14]. This paper is a generalization of this latter work to more general gauge groups

Warped Higgsless Models with IR--Brane Kinetic Terms

We examine a warped Higgsless $SU(2)_L\times SU(2)_R\times U(1)_{B-L}$ model in 5--$d$ with IR(TeV)--brane kinetic terms. It is shown that adding a brane term for the $U(1)_{B-L}$ gauge field does not affect the scale ($\sim 2-3$ TeV) where perturbative unitarity in $W_L^+ W_L^- \to W_L^+ W_L^-$ is violated. This term could, however, enhance the agreement of the model with the precision electroweak data. In contrast, the inclusion of a kinetic term corresponding to the $SU(2)_D$ custodial symmetry of the theory delays the unitarity violation in $W_L^\pm$ scattering to energy scales of $\sim 6-7$ TeV for a significant fraction of the parameter space. This is about a factor of 4 improvement compared to the corresponding scale of unitarity violation in the Standard Model without a Higgs. We also show that null searches for extra gauge bosons at the Tevatron and for contact interactions at LEP II place non-trivial bounds on the size of the IR-brane terms.Comment: 23 pages, 8 figure

Consistent couplings between spin-2 and spin-3 massless fields

We solve the problem of constructing consistent first-order cross-interactions between spin-2 and spin-3 massless fields in flat spacetime of arbitrary dimension n > 3 and in such a way that the deformed gauge algebra is non-Abelian. No assumptions are made on the number of derivatives involved in the Lagrangian, except that it should be finite. Together with locality, we also impose manifest Poincare invariance, parity invariance and analyticity of the deformations in the coupling constants.Comment: LaTeX file. 29 pages, no figures. Minor corrections. Accepted for publication in JHE