Deviations from the 1/r21/r^2 Newton law due to extra dimensions

We systematically examine corrections to the gravitational inverse square law, which are due to compactified extra dimensions. We find the induced Yukawa-type potentials for which we calculate the strength \alpha and range. In general the range of the Yukawa correction is given by the wavelength of the lightest Kaluza-Klein state and its strength, relative to the standard gravitational potential, by the corresponding degeneracy. In particular, when n extra dimensions are compactified on an n-torus, we find that the strength of the potential is \alpha=2n, whereas the compactification on an n-sphere gives \alpha= n+1. For Calabi-Yau compactifications the strength can be at most \alpha=20.Comment: 8 pages, latex, 1 figure; v2: References added and some clarifications in sec. 3 are made; v3: Physics Letters B versio

Brane Couplings from Bulk Loops

We compute loop corrections to the effective action of a field theory on a five-dimensional $S_1/Z_2$ orbifold. We find that the quantum loop effects of interactions in the bulk produce infinite contributions that require renormalization by four-dimensional couplings on the orbifold fixed planes. Thus bulk couplings give rise to renormalization group running of brane couplings.Comment: 10 pages, Latex with pictex figure

Renormalization Group and Dynamics of Supersymmetric Gauge Theories

We discuss questions related to renormalization group and to nonperturbative aspects of non-Abelian gauge theories with N=2 and/or N=1 supersymmetry. Results on perturbative and nonperturbative $\beta$ functions of these theories are reviewed, and new mechanisms of confinement and dynamical symmetry breaking recently found in a class of $SU(n_c)$, $USp(2n_c)$ and $SO(n_c)$ theories are discussed.Comment: 13 pages, 3 figures, uses ws-p9-75x6-50.cls. Lecture given at the Second Conference on the ERG, Rome 200

Theoretical Predictions for Collider Searches

I review recent developments in extensions of the Standard Model that address the question of electroweak symmetry breaking and discuss how these theories can be tested at future colliders.Comment: 13 pages, 2 figures, invited talk at the 21st International Symposium on Lepton and Photon Interactions at High Energies (Lepton Photon 2003), 11-16 Aug 2003, Batavia, Illinois, US

Limits on Low Scale Gravity from e+e−→W+W−,ZZe^+ e^- \to W^+ W^-, ZZ and γγ\gamma \gamma

It has been proposed recently that the scale of quantum gravity (``the string scale'') can be $M_S \sim$ few TeV with $n \geq 2$ extra dimensions of size $R \stackrel{<}{\sim}$ mm so that, at distances greater than $R$, Newtonian gravity with $M_{Pl} \sim 10^{18}$ GeV is reproduced if $M_{Pl}^2 \sim R^n M_S^{n+2}$. Exchange of virtual gravitons in this theory generates higher-dimensional operators involving SM fields, suppressed by powers of $M_S$. We discuss constraints on this scenario from the contribution of these operators to the processes $e^+ e^- \to W^+ W^-, ZZ, \gamma \gamma$. We find that LEP2 can place a limit $M_S \approx 1$ TeV from $e^+ e^- \to W^+ W^-, ZZ, \gamma \gamma$.Comment: Replacing an earlier version. A discussion of using polarized electron beams and some minor comments have been adde

Nonlinearity in Single Photon Detection: Modeling and Quantum Tomography

Single Photon Detectors are integral to quantum optics and quantum information. Superconducting Nanowire based detectors exhibit new levels of performance, but have no accepted quantum optical model that is valid for multiple input photons. By performing Detector Tomography, we improve the recently proposed model [M.K. Akhlaghi and A.H. Majedi, IEEE Trans. Appl. Supercond. 19, 361 (2009)] and also investigate the manner in which these detectors respond nonlinearly to light, a valuable feature for some applications. We develop a device independent model for Single Photon Detectors that incorporates this nonlinearity

Regression-Based Models for Predicting Discharge Coefficient of Triangular Side Orifice

- This study introduced another technique to predict the discharge coefficient (Cd) of the triangular side orifice (TSO). This technique is based on the SPSS software as multiple linear regression (MLR) and multiple nonlinear regression (MNLR) models. These models were established using 570 experimental datasets, 70 and 30% for calibration and testing stages, respectively. These sets considered five non-dimensional parameters, including (orifice crest height, orifice length, orifice height, upstream flow depth, and Froude number of the main channel). Results showed that the MLR and MNLR models in the calibrating stage had higher determination coefficients and lower errors. In addition, the importance of the input parameters was investigated, showing that the orifice crest height and Froude number highly affect the discharge coefficient value by 36%. In the testing stage, the estimated discharge coefficient by the MLR and MNLR models stayed within the range ±12 and ‡5%, respectively, of the experimental values. The MNLR model demonstrated a high level of equivalence compared to previous studies, which provided a mathematical expression to easily predict the TSO\u27s discharge coefficient