N=1 Supersymmetric Yang-Mills on the lattice at strong coupling

We study N=1 supersymmetric SU(N) Yang-Mills theory on the lattice at strong coupling. Our method is based on the hopping parameter expansion in terms of random walks, resummed for any value of the Wilson parameter r in the small hopping parameter region. Results are given for the mesonic (2-gluino) and fermionic (3-gluino) propagators and spectrum.Comment: Latex file. 43 pages. Minor additional comments, references added, typos corrected. Accepted for publication in Int. J. Mod. Phys.

A robust partial least squares method with applications

Partial least squares regression (PLS) is a linear regression technique developed to relate many regressors to one or several response variables. Robust methods are introduced to reduce or remove the effect of outlying data points. In this paper we show that if the sample covariance matrix is properly robustified further robustification of the linear regression steps of the PLS algorithm becomes unnecessary. The robust estimate of the covariance matrix is computed by searching for outliers in univariate projections of the data on a combination of random directions (Stahel-Donoho) and specific directions obtained by maximizing and minimizing the kurtosis coefficient of the projected data, as proposed by Peña and Prieto (2006). It is shown that this procedure is fast to apply and provides better results than other procedures proposed in the literature. Its performance is illustrated by Monte Carlo and by an example, where the algorithm is able to show features of the data which were undetected by previous methods.

Presynaptic Inhibition: Age-Related Changes in a Spinal Reflex Pathway

Older adults use more muscle activity than younger adults when performing the same motor task. There is evidence to suggest that age alters the spinal and cortical pathways that control coordinated movements between agonist and antagonist muscles. The purpose of the current work was to investigate the changes in presynaptic inhibition across young and old adults at rest and during isometric plantar flexion. The results of the study indicate that young adults were able to modulate the presynaptic inhibition pathway to a greater extent than old adults. The young adults demonstrated a significant decrease in the D1 conditioned soleus H-reflex at rest and during a plantar flexion contraction at 10% of maximum (rest: 48.2% ±16.0% of test H-reflex, P=0.001; plantar flexion: 52.9% ±25.0%; P=0.001), whereas the old adults only displayed a significant decrease in the H-reflex at rest (rest: 88.0 ±10.4% of test H-reflex, P=0.022; plantar flexion: 102 ±18.6%, P= 0.97). Additionally, there were greater levels of activity, although statistically insignificant, in the antagonist muscle (tibialis anterior) in old adults during plantar flexion (young plantar flexion: 4.9 ±3.7% MVC; old plantar flexion: 7.8 ±3.5% MVC), further supporting the notion that older adults rely more on descending commands than incoming sensory feedback when performing different physical tasks. This work provides further insight on the decline in neural function and can inform clinical work an future mechanistic studies

Solar Neutrinos Before and After Neutrino 2004

We compare, using a three neutrino analysis, the allowed neutrino oscillation parameters and solar neutrino fluxes determined by the experimental data available Before and After Neutrino 2004. New data available after Neutrino2004 include refined KamLAND and gallium measurements. We use six different approaches to analyzing the KamLAND data. We present detailed results using all the available neutrino and anti-neutrino data for Delta m^2_{12}, tan^2 theta_{12}, sin^2 theta_{13}, and sin^2 eta (sterile fraction). Using the same complete data sets, we also present Before and After determinations of all the solar neutrino fluxes, which are treated as free parameters, an upper limit to the luminosity fraction associated with CNO neutrinos, and the predicted rate for a 7Be solar neutrino experiment. The 1 sigma (3 sigma) allowed range of Delta m^2_{21} = (8.2 +- 0.3) (^+1.0_-0.8)times 10^{-5} eV^2 is decreased by a factor of 1.7 (5), but the allowed ranges of all other neutrino oscillation parameters and neutrino fluxes are not significantly changed. Maximal mixing is disfavored at 5.8 sigma and the bound on the mixing angle theta_{13} is slightly improved to sin^2 theta_{13}<0.048 at 3 sigma. The predicted rate in a 7Be neutrino-electron scattering experiment is (0.665 +-0.015) of the rate implied by the BP04 solar model in the absence of neutrino oscillations. The corresponding predictions for p-p and pep experiments are, respectively, 0.707 {+0.011}{-0.013} and 0.644 {+0.011}{-0.013}. We derive upper limits to CPT violation in the weak sector by comparing reactor anti-neutrino oscillation parameters with neutrino oscillation parameters. We also show that the recent data disfavor at 91 % CL a proposed non-standard interaction description of solar neutrino oscillations.Comment: Added predictions for p-p and pep neutrino-electron scattering rate; publishe

Global Analysis of Solar Neutrino Oscillations Including SNO CC Measurement

For active and sterile neutrinos, we present the globally allowed solutions for two neutrino oscillations. We include the SNO CC measurement and all other relevant solar neutrino and reactor data. Five active neutrino oscillation solutions (LMA, LOW, SMA, VAC, and Just So2) are currently allowed at 3 sigma; three sterile neutrino solutions (Just So2, SMA, and VAC) are allowed at 3 sigma. The goodness of fit is satisfactory for all eight solutions. We also investigate the robustness of the allowed solutions by carrying out global analyses with and without: 1) imposing solar model constraints on the 8B neutrino flux, 2) including the Super-Kamiokande spectral energy distribution and day-night data, 3) including a continuous mixture of active and sterile neutrinos, 4) using an enhanced CC cross section for deuterium (due to radiative corrections), and 5) a optimistic, hypothetical reduction by a factor of three of the error of the SNO CC rate. For every analysis strategy used in this paper, the most favored solutions all involve large mixing angles: LMA, LOW, or VAC. The favored solutions are robust, but the presence at 3 sigma of individual sterile solutions and the active Just So2 solution is sensitive to the analysis assumptions.Comment: 9 figures, higher resolution versions at http://www.sns.ias.edu/~jnb, added references and clarification

Recent results on self-dual configurations on the torus

We review the recent progress on our understanding of self-dual SU(N) Yang-Mills configurations on the torus.Comment: Latex 3 pages, 1 figure. Contribution to the Lat99 Proceeding

Updated determination of the solar neutrino fluxes from solar neutrino data

We present an update of the determination of the solar neutrino fluxes from a global analysis of the solar and terrestrial neutrino data in the framework of three-neutrino mixing. Using a Bayesian analysis we reconstruct the posterior probability distribution function for the eight normalization parameters of the solar neutrino fluxes plus the relevant masses and mixing, with and without imposing the luminosity constraint. We then use these results to compare the description provided by different Standard Solar Models. Our results show that, at present, both models with low and high metallicity can describe the data with equivalent statistical agreement. We also argue that even with the present experimental precision the solar neutrino data have the potential to improve the accuracy of the solar model predictions.Comment: 20 pages, 2 tables, 5 figures. arXiv admin note: substantial text overlap with arXiv:0910.458

Update on Solar and Atmospheric Four-Neutrino Oscillations

In this talk we present the update (including the recent SNO results) of our analysis of the neutrino oscillation solutions of the solar and atmospheric neutrino problems in the framework of four-neutrino mixing where a sterile neutrino is added to the three standard ones and the mass spectra present two separated doublets. Such scenarios allow for simultaneous transitions of solar $\nu_e$, as well as atmospheric $\nu_\mu$, into a combination of active and sterile neutrinos. We evaluate the allowed active-sterile admixture in both solar and atmospheric oscillations from the combined analysis. Our results show that, although the Super-Kamiokande data disfavour both the pure $\nu_\mu\to\nu_s$ atmospheric channel and, in combination with SNO, the pure $\nu_e\to\nu_s$ solar channel, the result from the combined analysis still favours close-to-pure active and sterile oscillations and disfavours oscillations into a near-maximal active-sterile admixture.In this talk we present the update (including the recent SNO results) of our analysis of the neutrino oscillation solutions of the solar and atmospheric neutrino problems in the framework of four-neutrino mixing where a sterile neutrino is added to the three standard ones and the mass spectra present two separated doublets. Such scenarios allow for simultaneous transitions of solar $\nu_e$, as well as atmospheric $\nu_\mu$, into a combination of active and sterile neutrinos. We evaluate the allowed active-sterile admixture in both solar and atmospheric oscillations from the combined analysis. Our results show that, although the Super-Kamiokande data disfavour both the pure $\nu_\mu\to\nu_s$ atmospheric channel and, in combination with SNO, the pure $\nu_e\to\nu_s$ solar channel, the result from the combined analysis still favours close-to-pure active and sterile oscillations and disfavours oscillations into a near-maximal active-sterile admixture.In this talk we present the update (including the recent SNO results) of our analysis of the neutrino oscillation solutions of the solar and atmospheric neutrino problems in the framework of four-neutrino mixing where a sterile neutrino is added to the three standard ones and the mass spectra present two separated doublets. Such scenarios allow for simultaneous transitions of solar $\nu_e$, as well as atmospheric $\nu_\mu$, into a combination of active and sterile neutrinos. We evaluate the allowed active-sterile admixture in both solar and atmospheric oscillations from the combined analysis. Our results show that, although the Super-Kamiokande data disfavour both the pure $\nu_\mu\to\nu_s$ atmospheric channel and, in combination with SNO, the pure $\nu_e\to\nu_s$ solar channel, the result from the combined analysis still favours close-to-pure active and sterile oscillations and disfavours oscillations into a near-maximal active-sterile admixture.In this talk we present the update (including the recent SNO results) of our analysis of the neutrino oscillation solutions of the solar and atmospheric neutrino problems in the framework of four-neutrino mixing where a sterile neutrino is added to the three standard ones and the mass spectra present two separated doublets. Such scenarios allow for simultaneous transitions of solar $\nu_e$, as well as atmospheric $\nu_\mu$, into a combination of active and sterile neutrinos. We evaluate the allowed active-sterile admixture in both solar and atmospheric oscillations from the combined analysis. Our results show that, although the Super-Kamiokande data disfavour both the pure $\nu_\mu\to\nu_s$ atmospheric channel and, in combination with SNO, the pure $\nu_e\to\nu_s$ solar channel, the result from the combined analysis still favours close-to-pure active and sterile oscillations and disfavours oscillations into a near-maximal active-sterile admixture

Perturbative construction of self-dual configurations on the torus

We develop a perturbative expansion which allows the construction of non-abelian self-dual SU(2) Yang-Mills field configurations on the four-dimensional torus with topological charge 1/2. The expansion is performed around the constant field strength abelian solutions found by 't Hooft. Next to leading order calculations are compared with numerical results obtained with lattice gauge theory techniques.Comment: latex file. 32 pages and 4 figures(24 eps files