The Atomic Lighthouse Effect

We investigate the deflection of light by a cold atomic cloud when the light-matter interaction is locally tuned via the Zeeman effect using magnetic field gradients. This "lighthouse" effect is strongest in the single-scattering regime, where deviation of the incident field is largest. For optically dense samples, the deviation is reduced by collective effects, as the increase in linewidth leads to a decrease of the magnetic field efficiency

Spatial and temporal localization of light in two dimensions

Quasi-resonant scattering of light in two dimensions can be described either as a scalar or as a vectorial electromagnetic wave. Performing a scaling analysis we observe in both cases long lived modes, yet only the scalar case exhibits Anderson localized modes together with extremely long mode lifetimes. We show that the localization length of these modes is influenced only by their position, and not their lifetime. Investigating the reasons for the absence of localization, it appears that both the coupling of several polarizations and the presence of near-field terms are able to prevent long lifetimes and Anderson localization.Comment: 5 pages, 4 figures and Supplementary Informatio

Electroweak corrections and anomalous triple gauge-boson couplings in WW and WZ production at the LHC

We have analysed the production of WW and WZ vector-boson pairs at the LHC. These processes give rise to four-fermion final states, and are particularly sensitive to possible non-standard trilinear gauge-boson couplings. We have studied the interplay between the influence of these anomalous couplings and the effect of the complete logarithmic electroweak O(\alpha) corrections. Radiative corrections to the Standard Model processes in double-pole approximation and non-standard terms due to trilinear couplings are implemented into a Monte Carlo program for p p -> 4f (+\gamma) with final states involving four or two charged leptons. We numerically investigate purely leptonic final states and find that electroweak corrections can fake new-physics signals, modifying the observables by the same amount and shape, in kinematical regions of statistical significance.Comment: 19 pages, LaTex, 12 eps figure

Correlation Function in Deep Redshift Space as a Cosmological Probe

Recent development of galaxy surveys enables us to investigate the deep universe of high redshift. We quantitatively present the physical information extractable from the observable correlation function in deep redshift space in a framework of the linear theory. The correlation function depends on the underlying power spectrum, velocity distortions, and the Alcock-Paczy\'nski (AP) effect. The underlying power spectrum is sensitive to the constituents of matters in the universe, the velocity distortions are sensitive to the galaxy bias as well as the amount of total matter, and the Alcock-Paczy\'nski effect is sensitive to the dark energy components. Measuring the dark energy by means of the baryonic feature in the correlation function is one of the most interesting applications. We show that the ``baryon ridge'' in the correlation function serves as a statistically circular object in the AP effect. In order to sufficiently constrain the dark energy components, the redshift range of the galaxy survey should be as broad as possible. The survey area on the sky should be smaller at deep redshifts than at shallow redshifts to keep the number density as dense as possible. We illustrate an optimal survey design that are useful in cosmology. Assuming future redshift surveys of z\simlt 3 which are within reach of the present-day technology, achievable error bounds on cosmological parameters are estimated by calculating the Fisher matrix. According to an illustrated design, the equation of state of dark energy can be constrained within $\pm 5$ error assuming that the bias is unknown and marginalized over. Even when all the other cosmological parameters should be simultaneously determined, the error bound for the equation of state is up to $\pm 10$.Comment: 13 pages, 8 figures, ApJ in pres

Curie-like paramagnetism due to incomplete Zhang-Rice singlet formation in La2-xSrxCuO4

In an effort to elucidate the origin of the Curie-like paramagnetism that is generic for heavily-overdoped cuprates, we have performed high transverse-field muon spin rotation (TF-muSR) measurements of La2-xSrxCuO4 single crystals over the Sr content range 0.145 < x < 0.33. We show that the x-dependence of the previously observed field-induced broadening of the internal magnetic field distribution above the superconducting transition temperature Tc reflects the presence of two distinct contributions. One of these becomes less pronounced with increasing x and is attributed to diminishing antiferromagnetic correlations. The other grows with increasing x, but decreases above x ~ 0.30, and is associated with the Curie-like term in the bulk magnetic susceptibility. In contrast to the Curie-like term, however, this second contribution to the TF-muSR line width extends back into the underdoped regime. Our findings imply a coexistence of antiferromagnetically correlated and paramagnetic moments, with the latter becoming dominant beyond x ~ 0.185. This suggests that the doped holes do not neutralize all Cu spins via the formation of Zhang-Rice singlets. Moreover, the paramagnetic component of the TF-muSR line width is explained by holes progressively entering the Cu 3d_{x^2-y^2} orbital with doping.Comment: 8 pages, 7 figure

Rate constant of the reaction of chlorine atoms with methanol over the temperature range 291–475 K

The rate constant of the reaction Cl + CH 3 OH ( k 1 ) has been measured in 500–950 Torr of N 2 over the temperature range 291–475 K. The rate constant determination was carried out using the relative rate technique with C 2 H 6 as the reference compound. Experiments were performed by irradiating mixtures of CH 3 OH, C 2 H 6 , Cl 2 , and N 2 with UV light from a fluorescent lamp whose intensity peaked near 360 nm. The resultant temperature-dependent rate expression is k 1 = 8.6 (±1.3) × 10 −11 exp[−167 (±60)/T] cm 3 molecule −1 s −1 . Error limits represent data scatter (2Σ) in the current experiments and do not include error in the reference rate constant. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 42: 113–116, 2010Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/64549/1/20474_ftp.pd

Catahoula formation of the Texas Coastal Plain : origin, geochemical evolution, and characteristics of uranium deposits

UT Librarie

Probing Dark Energy with Baryonic Acoustic Oscillations from Future Large Galaxy Redshift Surveys

We show that the measurement of the baryonic acoustic oscillations in large high redshift galaxy surveys offers a precision route to the measurement of dark energy. The cosmic microwave background provides the scale of the oscillations as a standard ruler that can be measured in the clustering of galaxies, thereby yielding the Hubble parameter and angular diameter distance as a function of redshift. This, in turn, enables one to probe dark energy. We use a Fisher matrix formalism to study the statistical errors for redshift surveys up to z=3 and report errors on cosmography while marginalizing over a large number of cosmological parameters including a time-dependent equation of state. With redshifts surveys combined with cosmic microwave background satellite data, we achieve errors of 0.037 on Omega_x, 0.10 on w(z=0.8), and 0.28 on dw(z)/dz for cosmological constant model. Models with less negative w(z) permit tighter constraints. We test and discuss the dependence of performance on redshift, survey conditions, and fiducial model. We find results that are competitive with the performance of future supernovae Ia surveys. We conclude that redshift surveys offer a promising independent route to the measurement of dark energy.Comment: submitted to ApJ, 24 pages, LaTe