131 research outputs found
Flipping t tbar asymmetries at the Tevatron and the LHC
We show that the charge asymmetry in t tbar production at the LHC, A_C, and
the forward-backward asymmetry at the Tevatron, A_FB, are in general not
tightly correlated. They can even have opposite signs, if the underlying new
physics (NP) model is general enough. We demonstrate this using two examples of
NP: a light axigluon, and a vector that is a color octet and electroweak
triplet. The small value of A_C measured at the LHC is thus shown not to
exclude a NP interpretation of the anomalously large A_FB at the Tevatron. We
identify two observables where significant NP effects are still expected at the
Tevatron and the LHC, the b bbar production forward-backward asymmetry and spin
polarizations of the pair-produced tops and anti-tops.Comment: 5 pages, 5 figure
Desorption Techniques for Determination of Metals Mobility in Soils
Three leaching techniques for assessment of fixed and mobile metal or radionuclides in soils are demonstrated on radiocaesium speciation. A new leaching technique based on the variation of the leaching solution volume to solid phase amount is proposed. It enables parallel treatment of large numbers of samples and, therefore, is suitable for a routine analysis of contaminant mobility in soils. As a leaching solution, 1 M ammonium acetate is proposed for caesium, but any other desorption solution harmonised with existing speciation schemes can be used
Semiconductor Bloch equation analysis of optical Stark and Bloch-Siegert shifts in monolayers WSe and MoS
We report on the theoretical and experimental investigation of
valley-selective optical Stark and Bloch-Siegert shifts of exciton resonances
in monolayers WSe and MoS induced by strong circularly polarized
nonresonant optical fields. We predict and observe transient shifts of both 1sA
and 1sB exciton transitions in the linear interaction regime. The theoretical
description is based on semiconductor Bloch equations. The solutions of the
equations are obtained with a modified perturbation technique, which takes into
account many-body Coulomb interaction effects. These solutions allow to explain
the polarization dependence of the shifts and calculate their values
analytically. We found experimentally the limits of the applicability of the
theoretical description by observing the transient exciton spectra change due
to many-body effects at high field amplitudes of the driving wave.Comment: 20 pages, 9 figures, this manuscript is related to the "Giant
valley-selective Stark and Bloch-Siegert shifts of exciton resonances in
WSe and MoS monolayers" manuscrip
- …