Away-side distribution in a parton multiple scattering model and background-suppressed measures

A model of parton multiple scattering in a dense and expanding medium is described. The simulated results reproduce the general features of the data. In particular, in the intermediate trigger momentum region there is a dip-bump structure, while at higher trigger momentum the double bumps merge into a central peak. Also, a new measure is proposed to quantify the azimuthal distribution with the virtue that it suppresses the statistical fluctuations event-by-event, while enhancing the even-structure of the signal.Comment: 4 pages including 7 figures. Talk presented at Hard Probes 200

Ridge And Transverse Correlation Without Long-Range Longitudinal Correlation

A simple phenomenological relationship between the ridge distribution in Delta eta and the single-particle distribution in eta can be established from the PHOBOS data on both distributions. The implication points to the possibility that it is not necessary to have long-range longitudinal correlation to explain the data. An interpretation of the relationship is then developed, based on the recognition that longitudinal uncertainty of the initial configuration allows for non-Hubble-like expansion at early time. It is shown that the main features of the ridge structure can be explained in a model where transverse correlation stimulated by semihard partons is the principal mechanism. This work is related to the azimuthal anisotropy generated by minijets in Au-Au collisions at 0.2 TeV on the one hand and to the ridge structure seen in pp collisions at 7 TeV on the other hand.Physic

Variations in propagation delay times for line ten (TV) based time transfers

Variation in the propagation delay for a 30 km TV (Line Ten) radio link was evaluated for a series of 30 independent measurements. Time marks from TV Channel 5 WTTG in Washington, D.C. were simultaneously measured at the Johns Hopkins University Applied Physics Laboratory and at the United States Naval Observatory against each stations' local cesium standard clocks. Differences in the stations' cesium clocks were determined by portable cesium clock transfers. Thirty independent timing determinations were made. The root mean square deviation in the propagation delay calculated from the timing determinations was 11 ns. The variations seen in the propagation delays are believed to be caused by environmental factors and by errors in the portable clock timing measurements. In correlating the propagation delay variations with local weather conditions, only a moderate dependence on air temperature and absolute humidity was found

Away-side azimuthal distribution in a Markovian parton scattering model

An event generator is constructed on the basis of a model of multiple scattering of partons so that the trajectory of a parton traversing a dense and expanding medium can be tracked. The parameters in the code are adjusted to fit the \Delta\phi azimuthal distribution on the far side when the trigger momentum is in the non-perturbative region, p_T(trigger)<4 GeV/c. The dip-bump structure for 1<p_T(assoc)<2.5 GeV/c is reproduced by averaging over the exit tracks of deflected jets. An essential characteristic of the model, called Markovian Parton Scattering (MPS) model, is that the scattering angle is randomly selected in the forward cone at every step of a trajectory that is divided into many discrete steps in a semi-classical approximation of the non-perturbative scattering process. Energy loss to the medium is converted to thermal partons which hadronize by recombination to give rise to the pedestal under the bumps. When extended to high trigger momentum with \pt(trigger) >8 GeV/c, the model reproduces the single-peak structure observed by STAR without invoking any new dynamical mechanism.Comment: 20 pages + 3 figure

Radiative Corrections to Longitudinal and Transverse Gauge Boson and Higgs Production

Radiative corrections to gauge boson and Higgs production computed recently using soft-collinear effective theory (SCET) require the one-loop high-scale matching coefficients in the standard model. We give explicit expressions for the matching coefficients for the effective field theory (EFT) operators for q qbar -> VV and q qbar -> phi^+ phi for a general gauge theory with an arbitrary number of gauge groups. The group theory factors are given explicitly for the standard model, including both QCD and electroweak corrections.Comment: 16 pages, 49 figure

Speed of light as measured by two terrestrial stable clocks

Despite the recent criticism within the special theory of relativity, there exists an arrangement of stable clocks rotating with the earth which predicts diurnal variations of the one-way speed of light, as suggested previously