Calculation of Electroproduction to NNLO and Precision Determination of αs\alpha_s

We use the known values of the two loop Wilson coefficients and the three loop anomalous dimension matrix $\gamma(n)$ to perform a next-to-next-to leading order (NNLO) calculation of $ep$ deep inelastic scattering. Because $\gamma(n)$ is only known for a few values of $n$, the method of average reconstruction has to be used, which leaves 102 effective experimental points, for 12 parameters: the QCD mass $\Lambda$, and 11 initial values for the moments of the structure functions. The data points spread in the range of momenta $2.5 GeV^2\leq Q^2\leq 230 GeV^2$. The chi/dof decreases substantially when going from LO to NLO, and also from NLO to NNLO (although only a little now) to $\chi/dof=79.2/(102-12)$. The favoured value of $\Lambda$ is $$\Lambda(n_f=4,3 {\rm loop})=282.7\pm35.1 MeV,$$ corresponding to the value of the coupling at the Z mass of $$\alpha^{(\rm 3 loop)}_s(M_Z^2)=0.1172\pm0.0024.$$ The calculation, which constitutes a very precise test of QCD, includes target mass corrections; the error takes into account experimental errors and higher twist effects among other estimated theoretical errors.Comment: revised version: change of \alpha_s(M_Z) from 0.1163 to 0.1172, and other minor alterations. Plain TeX fil

Non-Pauli Observables for CWS Codes

It is known that nonadditive quantum codes are more optimal for error correction when compared to stabilizer codes. The class of codeword stabilized codes (CWS) provides tools to obtain new nonadditive quantum codes by reducing the problem to finding nonlinear classical codes. In this work, we establish some results on the kind of non-Pauli operators that can be used as decoding observables for CWS codes and describe a procedure to obtain these observables

Observable contributions of new exotic quarks to quark mixing

Models with new vector-like quarks can produce observable quark mixing effects which are forbidden in the Standard Model. We classify all such models and write down the effective Lagrangian that results from integrating out the new quarks. We study the relations between neutral and charged currents and discuss how to distinguish among the different possibilities.Comment: 15 pages, 1 figure, typos corrected, version to appear in JHE

Bulk fields with brane terms

In theories with branes, bulk fields get in general divergent corrections localized on these defects. Hence, the corresponding brane terms are renormalized and should be included in the effective theory from the very beginning. We review the phenomenology associated to brane kinetic terms for different spins and backgrounds, and point out that renormalization is required already at the classical level.Comment: Presented at HEP2003, International Europhysics Conference on High Energy Physics (July 17-23, 2003) Aachen, German

Differential systems with reflection and matrix invariants

In this work we derive important properties regarding matrix invariants which occur in the theory of differential equations with reflection.Comment: Preprin