29,281 research outputs found
Detecting the breached pair phase in a polarized ultracold Fermi gas
We propose a method for the experimental detection of a new quantum phase,
the breached pair state, in a strongly interacting ultracold Fermi gas with
population imbalance. We show that through the time-of-flight Raman imaging,
the presence of such a phase can be unambiguously determined with a measurement
of the momentum-space phase separation of the minority spin component. To guide
the experimental efforts, the momentum-space density profiles are calculated
under typical experimental conditions.Comment: 4 pages, 3 figures, replaced with the published versio
Trapped Fermions across a Feshbach resonance with population imbalance
We investigate the phase separation of resonantly interacting fermions in a
trap with imbalanced spin populations, both at zero and at finite temperatures.
We directly minimize the thermodynamical potential under the local density
approximation instead of using the gap equation, as the latter may give
unstable solutions. On the BEC side of the resonance, one may cross three
different phases from the trap center to the edge; while on the BCS side or at
resonance, typically only two phases show up. We compare our results with the
recent experiment, and the agreement is remarkable.Comment: 4 pages, 3 figures, replaced with the published versio
Exploring Resonant di-Higgs production in the Higgs Singlet Model
We study the enhancement of the di-Higgs production cross section resulting
from the resonant decay of a heavy Higgs boson at hadron colliders in a model
with a Higgs singlet. This enhancement of the double Higgs production rate is
crucial in understanding the structure of the scalar potential and we determine
the maximum allowed enhancement such that the electroweak minimum is a global
minimum. The di-Higgs production enhancement can be as large as a factor of ~
18 (13) for the mass of the heavy Higgs around 270 (420) GeV relative to the
Standard Model rate at 14 TeV for parameters corresponding to a global
electroweak minimum.Comment: 25 pages, 14 figures. Version approved for publication. Discussion of
Z2 symmetric limit improved and references adde
Top Partners and Higgs Boson Production
The Higgs boson is produced at the LHC through gluon fusion at roughly the
Standard Model rate. New colored fermions, which can contribute to
, must have vector-like interactions in order not to be in
conflict with the experimentally measured rate. We examine the size of the
corrections to single and double Higgs production from heavy vector-like
fermions in singlets and doublets and search for regions of parameter
space where double Higgs production is enhanced relative to the Standard Model
prediction. We compare production rates and distributions for double Higgs
production from gluon fusion using an exact calculation, the low energy theorem
(LET), where the top quark and the heavy vector-like fermions are taken to be
infinitely massive, and an effective theory (EFT) where top mass effects are
included exactly and the effects of the heavy fermions are included to . Unlike the LET, the EFT gives an extremely accurate description
of the kinematic distributions for double Higgs production.Comment: 37 pages, 11 figures. Minor changes to Figs. 8-1
Galpha 12 and Galpha 13 Are Phosphorylated during Platelet Activation
The ubiquitously expressed G-proteins G12 and G13 whose function is currently not clear have been shown to be activated in platelet membranes through receptors that stimulate platelet aggregation. We used intact human platelets to determine whether alpha subunits of both G-proteins can be phosphorylated under physiological conditions. Activation of human platelets by thrombin and the thromboxane A2 receptor agonist U46619 lead to phosphorylation of Galpha 12 and Galpha 13. Phosphorylation occurred rapidly after addition of thrombin and was not mediated by glycoprotein IIb/IIIa (integrin alpha IIbbeta 3) activation. Phosphorylation of Galpha 12 and Galpha 13 could be mimicked by phorbol 12-myristate 13-acetate, and thrombin-induced phosphorylation was inhibited by the protein kinase C inhibitor calphostin C indicating an involvement of protein kinase C in Galpha 12/13 phosphorylation induced by thrombin in human platelets. The phosphorylation of both G protein alpha subunits was reconstituted in COS-7 cells cotransfected with Galpha 12 or Galpha 13 and different protein kinase C isoforms. Among the protein knase C isoforms tested, protein kinase C beta , delta , and epsilon were most effective in promoting phosphorylation of Galpha 12 and Galpha 13 in a phorbol 12-myristate 13-acetate-dependent manner. These data demonstrate that Galpha 12 and Galpha 13 are phosphorylated under in vivo conditions and that this phosphorylation involves protein kinase C
Hot One-Temperature Accretion Flows Around Black Holes
We describe hot, optically-thin solutions for one-temperature accretion disks
around black holes. We include cooling by synchrotron, bremsstrahlung, and
Comptonization. Our solutions are thermally and viscously stable, with gas
temperatures on the order of K. The thermal stability is
a direct result of the inclusion of synchrotron cooling.
The new solution branch is related to the advection-dominated solution for a
two-temperature gas described by Narayan \& Yi (1995b). It is present only for
mass accretion rates less than some critical which depends on
the radius and viscosity parameter . The solutions are
advection-dominated for extremely low values of . However, for a range
of intermediate accretion rates, the new solutions are both hot (K) and cooling-dominated. Because of this new feature, one-temperature
solutions are significantly more luminous than the corresponding two
temperature solutions.
The radial profile of the new solutions is unusual. The inner parts of the
flow are cooling-dominated and have a disk-like geometry, while the outer parts
are fully advection-dominated and nearly quasi-spherical.Comment: 24 pages tex file and 7 postscript figures all included in one
compressed tar file. Accepted for publication in ApJ. In case of problems,
write to [email protected]
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