1 Tribute to Daniel Gogny 08/12/15

Detours may (sometime) be the best way,

views from former physicists

D. Iracane & P. Chaix, CEA/Saclay

2 Tribute to Daniel Gogny 08/12/15

Being a disciple of Daniel Gogny approach

In 1982, Daniel Gogny was searching in QFT some rationale for his successful Force

Later in the 80s, the Strategic Defense US initiative raised questions about the Free Electron Laser operational capacities

Fundamental approaches within an “applied science organization”:Questions arising from operational considerations.

Work for a deep understanding,in an open, free and rigorous approach.

Push (when possible) up to the end of the story,whatever the detours, to get robust results.

Fun and excitement!

3 Tribute to Daniel Gogny 08/12/15

Daniel’s program1981: nucleon-nucleon interaction, looking for a deeper

insight justification from Quantum Chromodynamics

Using tools with proven efficiency: Effective force variational methods and mean field theory

An intricate topic with severe issues, gauge invariance, renormalisation …

But interesting results

4 Tribute to Daniel Gogny 08/12/15

Looking for an attractive channel, the effective force, a tricky point

Numerical and Mathematical analysis exhibits a competition between 2 phases:- Supraconducting condensate- Bose-Einstein condensate

Gluon condensate studywithin Hartree Fock Bogoliubov mean field theory

5 Tribute to Daniel Gogny 08/12/15

Getting deeper insight relativistic N-body mean field theory

In Quantum Electrodynamics

A domain where forces are well known … … with operational stakes

COMPUTATION OF HEAVY IONS/ATOMS

6 Tribute to Daniel Gogny 08/12/15

From numerical relativistic atomic calculations with Density Functional method

Result in accurate eigenstatesPlus …

A “Spurious” eigenstate

Dirac Hamiltonian with Coulomb interaction bounded from below ?

Hydrogen-like Iron

UU

Z > 137 = 1/α

7 Tribute to Daniel Gogny 08/12/15

… back to fundamental issues

The BDF QED vacuum is stable if α < 4/π(by « chance », α = 1/137 < 4/ π …)

What is the vacuum of QEDfor relativistic Bogoliubov-Dirac-Fock

variational calculations of atoms?

8 Tribute to Daniel Gogny 08/12/15

Meanwhile, the SDIO in USA …

Large power Free Electrons Laser

Operational capacities for Defence applications ?

The ELSA high power, long pulse FEL in CEA

9 Tribute to Daniel Gogny 08/12/15

The non-lineal spectral broadening

←Main frequency F1

←So-called « Sideband » F2

←new effect F3=f(F1,F2)

10 Tribute to Daniel Gogny 08/12/15

11 Tribute to Daniel Gogny 08/12/15

Exp. Num. Theory

Consistent numerical, theoretical and experimental results

12 Tribute to Daniel Gogny 08/12/15

Operational results: FEL can store a significant power …

… by loosing laser coherence

Except if…

13 Tribute to Daniel Gogny 08/12/15

A part of the heritage: How to identify the most important texts