144,094 research outputs found
Sensitivity to Contact Interactions and Extra Dimensions in Di-lepton and Di-photon Channels at Future Colliders
Virtual effects from a generic description of physics beyond the Standard
Model in terms of contact interactions, or from large extra dimensions will
modify the observed cross sections for easy to detect final states like lepton
or photon pairs, and can be used to probe scales much higher than the
center-of-mass energy of the partons initiating the interactions. In this note
the sensitivity reach of the Large Hadron Collider to contact interactions in
the Drell-Yan channels and of a Future Linear Collider to contact interactions
and extra dimensions in , and final states
are studied. Experimental aspects of the measurements, systematic error effects
and the evolution of the search reach with accumulated luminosity are
considered.Comment: 13 pages, 2 figures, 8 tables; Contribution to LHC / LC Study Group
Working Documen
Longitudinal spin Seebeck coefficient: heat flux vs. temperature difference method
The determination of the longitudinal spin Seebeck effect (LSSE) coefficient
is currently plagued by a large uncertainty due to the poor reproducibility of
the experimental conditions used in its measurement. In this work we present a
detailed analysis of two different methods used for the determination of the
LSSE coefficient. We have performed LSSE experiments in different laboratories,
by using different setups and employing both the temperature difference method
and the heat flux method. We found that the lack of reproducibility can be
mainly attributed to the thermal contact resistance between the sample and the
thermal baths which generate the temperature gradient. Due to the variation of
the thermal resistance, we found that the scaling of the LSSE voltage to the
heat flux through the sample rather than to the temperature difference across
the sample greatly reduces the uncertainty. The characteristics of a single
YIG/Pt LSSE device obtained with two different setups was Vm/W and Vm/W with the heat flux method
and V/K and V/K
with the temperature difference method. This shows that systematic errors can
be considerably reduced with the heat flux method.Comment: PDFLaTeX, 10 pages, 6 figure
Control of a train of high purity distillation columns for efficient production of 13C isotopes
It is well-known that high-purity distillation columns are difficult to control due to their ill-conditioned and strongly nonlinear behaviour. The fact that these processes are operated over a wide range of feed compositions and flow rates makes the control design even more challenging. This paper proposes the most suitable control strategies applicable to a series of cascaded distillation column processes. The conditions for control and input-output relations are discusssed in view of the global control strategy. The increase in complexity with increased number of series cascaded distillation column processes is tackled. Uncertainty in the model parameters is discussed with respect to the dynamics of the global train distillation process. The main outcome of this work is insight into the possible control methodologies for this particular class of distillation processes
A semi-empirical representation of the temporal variation of total greenhouse gas levels expressed as equivalent levels of carbon dioxide
Abstract and PDF report are also available on the MIT Joint Program on the Science and Policy of Global Change website (http://globalchange.mit.edu/).In order to examine the underlying longer-term trends in greenhouse gases, that are driven for example by anthropogenic emissions or climate change, it is useful to remove the recurring effects of natural cycles and oscillations on the sources and/or sinks of those gases that have strong biological (e.g., CO2, CH4, N2O) and/or photochemical (e.g. CH4) influences on their global atmospheric cycles. We use global observations to calculate monthly estimates of greenhouse gas levels expressed as CO2 equivalents, and then fit these estimates to a semi-empirical model that includes the natural seasonal, QBO, and ENSO variations, as well as a second order polynomial expressing longer-term variations. We find that this model provides a reasonably accurate fit to the observation-based monthly data. We also show that this semiempirical model has some predictive capability; that is it can be used to provide a reasonably reliable estimate of CO2 equivalents at the current time using validated observations that lag real time by a few to several months.This study received support from the MIT Joint Program on the Science and Policy of Global Change, which is funded by a consortium of government, industry and foundation sponsors
Early Searches with Jets with the ATLAS Detector at the LHC
We summarize the analysis of high-pT jets in early pp collisions recorded
with the ATLAS detector. Two searches for new physics are presented: One for
dijet resonances, and one for quark contact interactions. The first search sets
the most stringent current limit on the mass of a hypothetical excited quark.Comment: 4 pages, 5 figures, Proceedings of the 35th International Conference
of High Energy Physics (ICHEP 2010), Paris, France, July 22-28, 201
Dipolar and scalar He and Xe frequency shifts in mm-sized cells
We describe a He-Xe comagnetometer operating in stemless
anodically bonded cells with a 6 mm volume and a Xe spin coherence
time of 300 sec. We use a Rb pulse-train magnetometer with co-linear
pump and probe beams to study the nuclear spin frequency shifts caused by spin
polarization of He. By systematically varying the cell geometry in a
batch cell fabrication process we can separately measure the cell shape
dependent and independent frequency shifts. We find that a certain aspect ratio
of the cylindrical cell can cancel the effects of He magnetization that
limit the stability of vapor-cell comagnetometers. Using this control we also
observe for the first time a scalar He-Xe collisional frequency
shift characterized by an enhancement factor .Comment: 4 pages, 4 figure
Review of Final LEP Results or A Tribute to LEP
After a comment on the performance of LEP some highlights of the LEP1 and
LEP2 physics programmes are reviewed. The talk concentrates on the precision
measurements at the Z resonance, two fermion production above the Z, W+W-
production, ZZ production, indirect limits on the Higgs mass, LEP contributions
to the exploration of the CKM matrix, and on the LEP measurements of alpha_s.Comment: Proceedings of the XX International Symposium on Lepton and Photon
Interactions at High Energies Rome, Italy, July 200
TESLA Technical Design Report Part III: Physics at an e+e- Linear Collider
The TESLA Technical Design Report Part III: Physics at an e+e- Linear
ColliderComment: 192 pages, 131 figures. Some figures have reduced quality. Full
quality figures can be obtained from http://tesla.desy.de/tdr. Editors -
R.-D. Heuer, D.J. Miller, F. Richard, P.M. Zerwa
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