Theme « gauge theory »

Chercheurs :

Maxim Chernodub, Stam Nicolis, Antti Niemi, Shuangwei Hu.

Présentation :

Protein folding (Antti Niemi, Shiangwei Hu, Stam Nicolis, Maxim Chernodub).

The aim of this research project is to apply fundamental concepts in theoretical high energy physics/quantum field (string) theory and related mathematical physics to describe problems in biological physics and protein folding. Protein matching

Indeed, the correct three dimensional conformation of a protein is essential for its proper biological function, while a failure to fold into the native state produces either an inactive protein or a protein that has biologically wrong properties. As a consequence unraveling the principles that underlie the mechanism of protein folding will not only explain the great mystery how living organisms function but it may also result in a much better understanding and even cures for illnesses such as several forms of cancer, neurodegenerative pathologies, and many other diseases that are supposedly caused by misfolded proteins. The methods that have been developed in high energy physics have often found wider ramifications to other subfields of Physics. In the very same spirit, our group is interested in the construction and analysis of the geometrical shape of string-like structures with applications to biophysics and protein folding, arguably the most important problem in biology. The aim of the group is to develop the Abelian Higgs model as a phenomenological field theory model of folded proteins. The project is a cross-disciplinary study of relations between low dimensional field theories and protein folding.


Strong magnetic fields (Maxim Chernodub)

One of the acticities of the group is devoted to theoretical efforts to reveal an exotic role of hyperstrong magnetic fields which are created in collisions of heavy nuclei at high energies. The collisions create strongly interacting matter at energy densities that are much above the density of a normal nucleus.
Superconducting vortex lattice

It is likely, that a new state of superdense and strongly interacting matter, the quark-gluon plasma, is formed at the centre of the collision. The physics of collisions may be studied theoretically using field theory methods (nonperturbative quantum chromodynamics, various effective models of strong interactions etc). The next-generation experiment, devoted to the investigation of the quark-gluon matter in heavy-ion collisions is A Large Ion Collider Experiment (ALICE), located at the just-started Large Hadron Collider (LHC) at CERN, at the border of France and Switzerland. The huge energy of the collision (about 2.8 teraelectronvolt per nucleon at a centre of mass) provides extraordinarily good conditions to study the quark-gluon plasma under controlled laboratory conditions.

Knotted magnetic fields in quark-gluon plasma

The interest in the collisions is motivated by the fact that the colliding nuclei produce (besides the plasma) strongest magnetic fields in the present-day Universe. The magnetic fields in heavy-ion collisions at CERN are expected to reach 10^15 Tesla, what is at least five orders of magnitude stronger compared to magnetic fields at a surface of a highly magnetized neutron star, a magnetar. The strong magnetic field may lead to many exotic effects either in the vacuum or in dense/hot matter such as generation of the electric current of quarks along the direction of an external magnetic field (even in the absence of an external electric field), noticeable splitting of the deconfinement and chiral restoration transitions at finite temperature, formation of solitons made of knotted magnetic fields, emergence of an electromagnetically superconducting phase at low temperature etc. We expect that such effects may be tested experimentally at the ALICE facility at LHC (CERN).


Spin-charge separation (Antti Niemi, Maxim Chernodub).

Conventionally, the spin and the charge are considered to be among the fundamental characteristics of an elementary particle. Many elementary particles such as an electron carry both a non-trivial spin and a non-trivial charge, without any kind of (high energy) experimental indications that the presence of both spin and charge could somehow mean that there could be some nontrivial internal structure. To the contrary, any high-energy experiment that has tested the internal structure of an electron unequivocally comes to the conclusion that the higher its energy, the more point-like it behaves. However, some time ago condensed matter physicists felt compelled to propose that in certain strongly correlated environments electrons can effectively become decomposed into independent spin and charge carriers. In particular, such spin-charge separation has been investigated in the context of Hubbard model, as a possible mechanism for explaining high temperature superconductivity in cuprates.

The separation between the spin and the charge, if it exists, has a huge potential in particular in particle physics where strongly correlated environments are much more common and also much easier to achieve than in condensed matter. Thinkable scenarios range from Early Universe to compact stars, maybe even all the way to the structure of hadronic particles and ordinary hadronic matter. Our goal is to develop and understand the role and meaning of spin-charge separation in high energy physics using quantum field theoretical methods. This activity has a clear cross-disciplinary component, several of the ideas presented here are parallel to ideas that have been presented in condensed matter physics. Furthermore, this concept may appear in a variety of different physical environments, from confining structures in hadron physics to problems in both traditional and quantum fluid mechanics and scenarios in magnetohydrodynamical plasma that describes the solar photosphere. Finally, a branch of this research proposal aims to be directly relevant to problems in molecular biology and genetics.