The SEMPARIS seminar webserver hosts annoucements of all seminars taking place in Paris area, in all topics of physics, mathematics and computer science. It allows registered users to receive a selection of announcements by email on a daily or weekly basis, and offers the possibility to archive PDF or Powerpoint files, making it available to the scientific community. [ More information ]
Upcoming Seminars at LPTHE  
[ scheduler view ] 
Thursday 20 June 2019, 10:00 at IHP, Salle 314  RENCTHEO (Rencontres Théoriciennes)  condmat.strelhepth 



Abstract:  It is wellknown that zerotemperature Hall conductance of a 2d system can be interpreted both as a bulk transport coefficient and a U(1) anomaly for the edge modes. The former interpretation allows one to write down a simple formula for it (Kubo formula). The latter interpretation explains why Hall conductance is a topological invariant. In this talk I will explain the difficulties in extending these considerations to thermal Hall conductance and how they are overcome. I argue that thermal Hall conductance should be regarded as an exact 1form on the parameter space rather than a function. Another observation is that anomalies of edge modes can be interpreted in physical terms as violations of F. Bloch’s theorem about the absence of currents in an equilibrium state. Combining these observations, I show that lowtemperature thermal Hall conductance of a gapped 2d system is robust under arbitrary deformations which do not close the gap. 
Thursday 20 June 2019, 11:40 at IHP, 314  RENCTHEO (Rencontres Théoriciennes)  hepth 



Abstract:  The physics of Quantum Chromodynamics (QCD) at high density is notoriously difficult to study by conventional methods. Yet this physics will be probed by future observations of gravitational wave signals coming from neutron star mergers. I will discuss what light holography can shed on this difficult regime, paying particular attention to possible crystalline and color superconducting phases. 
Friday 21 June 2019, 11:00 at LPTHE, Bibliothèque  SEMLPTHE (Séminaire du LPTHE)  condmat.statmech 



Abstract:  At present theoretical prediction for the spinaveraged frequency of rovibrational transitions in the hydrogen molecular ions (HMI) has reached a relative precision of $\sim\!7.5\!\times\!10^{12}$. On the other hand, recent experiment on pure rotational transition in HD$^+$ has demonstrated the power of the LambDicke regime for precision spectroscopy of the HMI with strong potentiality in the nearest future to achieve a ppt level of spectroscopic accuracy. The Rydberg constant as it is determined in the CODATA14 adjustment of the fundamental constants has the relative uncertainty $5.9\!\times\!10^{12}$. At the same time the two new experiments on spectroscopy of hydrogen atom performed at LKB, Paris, and MPQ, Munich, disagree in measuring the Rydberg constant by more than $3\sigma$! In our presentation we want to outline the way how the high precision results for the hydrogen molecular ions may be achieved with the help of the effective field theory  the Nonrelativistic QED. At the very end of our talk we intend to discuss the problems, which are to be solved in order to improve (at least threefold) theoretical predictions. That will bring our theory to the level of accuracy which is better than for the present CODATA14 value of the Rydberg constant. And, we hope, that this will help to resolve the discrepancy between the LKB and MPQ experiments as well as to find answers to many other questions related to the fundamental constants. 
Tuesday 23 July 2019, 14:00 at LPTHE, library  LPTHEPPH (Particle Physics at LPTHE)  hepph 


Friday 26 July 2019, 14:00 at LPTHE, library  LPTHEPPH (Particle Physics at LPTHE)  hepph 



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