Institut de Physique Théorique
Direction des Sciences de la Matière  - CEA-Saclay
Unité de Recherche Associée au CNRS
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Monday, April 27, 2015

Welcome to IPhT

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Agenda

Today

14h00 Soutenance de thèse de doctorat

Soutenance de thèse de doctorat

Amphi Claude Bloch, Bât. 774 Orme des Merisiers

Eric Vernier

Wednesday, Apr 29, 2015

14h15 Séminaire hadronique et des particules

Séminaire hadronique et des particules

Salle Claude Itzykson, Bât. 774 Orme des Merisiers

Paolo Creminelli

Monday, May 04, 2015

11h00 Séminaire de physique mathématique

Séminaire de physique mathématique

Salle Claude Itzykson, Bât. 774 Orme des Merisiers

Gernot Akemann

Tuesday, May 05, 2015

14h15 Séminaire de matrices, cordes et géométries aléatoires

Séminaire de matrices, cordes et géométries aléatoires

Salle Claude Itzykson, Bât. 774 Orme des Merisiers

Oluf Engelund

Wednesday, May 06, 2015

14h15 Séminaire hadronique et des particules

Séminaire hadronique et des particules

Salle Claude Itzykson, Bât. 774 Orme des Merisiers

Dario Buttazzo


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The Institut de Physique Théorique (IPhT) is a laboratory of fundamental research, located in Saclay, about 20 km south-west of Paris.

The research performed at the IPhT aims at better understanding the laws which govern our universe and its organisation. It encompasses most of the great subjects of modern theoretical physics:

The IPhT comprises about fifty permanent physicists (2/3 CEA, 1/3 CNRS), about thirty PhD students and postdocs, assisted by a support staff of about ten people. The IPhT also hosts permanently many short term visitors.

News

Bending of Light in Quantum Gravity   

imgA century ago Albert Einstein used his new theory of gravity – the general relativity - for evaluating the bending angle of rays of light under the gravitational pull from the Sun. Ludovic Planté, Pierre Vanhove and their colleagues have evaluated for the first time the quantum gravity correction to this bending angle.

The computation is done in the framework of the low-energy effective field theory, which allows evaluating large distance effects by keeping only low energy fields and couplings. This contribution is universal to any theory of quantum because since it is independent of (any unknown) high-energy degrees of freedom.

The quantum correction depends on the spin of the deflected massless particle, in contrast to the classical contribution. Therefore it violates the equivalence principle but preserves the fundamental symmetries of the theory on which Einstein based his theory of general relativity.

"Bending of Light in Quantum Gravity", N. E. J. Bjerrum-Bohr, John F. Donoghue, Barry R. ...

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C. Pepin, 2015-04-08

 

RNA: The unknotted strands of life   

img No one had checked before, but RNA, the nucleic acid involved in many cell functions including protein synthesis, appears to be the only « strand of life » not to have knots.

Over the years, advances in structural biology have firmly established that both proteins and DNA, although subject to evolutionary selection, do not escape the statistical law whereby a sufficiently long and compacted molecular strand will inevitably be entangled. However, no one to date had looked into the case of RNA.

Using the structural description provided for approximately 6,000 RNA chains entered in the Protein Data Bank, a team of researchers from the SISSA (Italy) and the IPhT has performed a thorough study of the presence of knots in these biopolymers.

In order to detect knots, they used the following methods:

  1. Circularize the RNA chain by joining its extremities using the « minimally invasive » scheme
  2. Simplify locally the structure by iteratively removing obviously unknotted parts
  3. Compute the Alexander determinants, and for more ...

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F. David, 2015-04-08

 

Liouville Quantum Gravity on the Riemann Sphere   

imgIn 1981, the famous theoretician A. Polyakov introduced the quantum Liouville theory as a model for the quantized string. This theory “quantizes” the Liouville equation R=-1 of classical geometry, which characterizes Riemann surfaces with negative curvature. It is thus a quantum theory of gravity, where the geometry of a two dimensional space-time in quantized (1 time dimension + 1 space dimension).

Liouville theory has remarkable properties. It is a conformal theory (it is endowed with an infinite symmetry group, the same as for string theories and critical systems such as the Ising model in two dimensions). Liouville theory appears, sometimes unexpectedly, in many problems of theoretical physics and of pure mathematics. It has been therefore very much studied via the methods of Conformal Field Theory and of Integrable Systems. But it is also related, in a deep but still partially understood way, to combinatorial models where space-time is discretized as a random lattice (random maps, matrix models). In these two approaches (continuous and discrete) the IPhT has brought major contributions.

Recently a third player entered this arena: probability theory! It already led to a better ...

More »

 
C. Pepin, 2015-02-24

 

20ème conférence Itzykson, Surfaces et géométries aléatoires, 10-12 juin 2015

A new, yet faster, version of FastJet

Uncovering the spatial structure of mobility networks

Spin Vertex and 3 Point Function in AdS/CFT Correspondence

Hélène Dupuy receives a "L'Oréal - UNESCO for women in science" fellowship

Roger Balian and François David interviewed on quantum physics

Robi Peschanski on air on France Culture

Marco Cirelli awarded the Thibaud Prize of the académie de Lyon


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