Showing posts with label qgp. Show all posts
Showing posts with label qgp. Show all posts

Sunday, March 01, 2015

Visualizations are Important

Figure 1: Artist's conception of AdS/CFT. The evolution of the proton at different
length scales is mapped into the compact AdS5 dimension z. Dirichlet bag-like boundary
condition,     (z)jz=z0 = 0, is imposed at the confinement radius z = z0 = 1= QCD,
thus limiting interquark separations.

String theorists describe the physics of black holes in five-dimensional space-time. They found that these five-dimensional objects provide a good approximation of the quark-gluon plasma in one fewer dimension, a relationship similar to the one between a three-dimensional object and its two-dimensional shadow. Image: SLAC National Accelerator Laboratory

Recreating the conditions present just after the Big Bang has given experimentalists a glimpse into how the universe formed. Now, scientists have begun to see striking similarities between the properties of the early universe and a theory that aims to unite gravity with quantum mechanics, a long-standing goal for physicists.
“Combining calculations from experiments and theories could help us capture some universal characteristic of nature,” said MIT theoretical physicist Krishna Rajagopal, who discussed these possibilities at the recent Quark Matter conference in Annecy, France.

One millionth of a second after the Big Bang, the universe was a hot, dense sea of freely roaming particles called quarks and gluons. As the universe rapidly cooled, the particles joined together to form protons and neutrons, and the unique state of matter known as quark-gluon plasma disappeared. See: String theory may hold answers about quark-gluon plasma

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Thursday, February 05, 2015

Superfluidity and the Roton

University of Chicago scientists can create an exotic, particle-like excitation called a roton in superfluids with the tabletop apparatus pictured here. Posing left to right are graduate students Li-Chung Ha and Logan Clark, and Prof. Cheng Chin.

See: Cesium atoms shaken, not stirred, to create elusive excitation in superfluid 

We present experimental evidence showing that an interacting Bose condensate in a shaken optical lattice develops a roton-maxon excitation spectrum, a feature normally associated with superfluid helium. The roton-maxon feature originates from the double-well dispersion in the shaken lattice, and can be controlled by both the atomic interaction and the lattice modulation amplitude. We determine the excitation spectrum using Bragg spectroscopy and measure the critical velocity by dragging a weak speckle potential through the condensate—both techniques are based on a digital micromirror device. Our dispersion measurements are in good agreement with a modified Bogoliubov model. DOI:

Thursday, January 22, 2015

Quantum Chromodynamics

Source -

Nobel Prize laureate David Gross on Rutherford experiments, asymptotic freedom, and the origin of the particle masses