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LAPTh, an overview

LAPTh is a mixed research unit (UMR 5108) of the CNRS lapth-lapp(within the Institute of Physics, INP) and the Université de Savoie. It is  located in Annecy-le-Vieux, 5km from the centre of Annecy and about 40km from CERN and Geneva.  The activities of LAPTh are centred around three main areas of research:

  • phenomenology of particle physics,
  • astroparticles and cosmology,
  • mathematical physics in particular field and string theory and  aspects of symmetry. 

News

International Indo-French Laboratory: IFTHEP

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 LAPTh (F. Boudjema) is coordinating an Indo French Laboratory, LIA  (Laboratoire International Associé). The Indian coordinator is Rohini Godbole of the IISc (Indian Institute of Science) in Bangalore. The set up of the LIA is well timed since it covers the physics of the LHC, the LHC has just started colliding beams to achieve the unprecedented total centre of mass energy of 13TeV. After the discovery of the Higgs we are hoping that the opening up of this new threshold will allow discoveries that will shed light on the mysteries of the Higgs and provide clues about dark matter. The other major topic of the LIA is the study of the quark gluon plasma which intimately should provide clues about how matter forms in extreme conditions.

The LIA is structured around 4 nodes in each country. Participating laboratories represent the leading theory groups in both country with a high visibility internationally. The French laboratories are LAPTh, LPSC Grenoble, IPN Lyon, LPT Orsay, CPhT (Ecole Polytechnique) and IPhT CEA Saclay. On the Indian part beside IISc we have TIFR Mumbai, SINP/IACS/IISER Kolkata, IMSc Chennai and HRI Allahabad. The LIA IFTHEP (Indo French Theory High Energy Physics) , will run for an initial period of 4 years.

 

Refined background calculations for AMS02

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The latest results from the AMS-02 experiment were announced in mid-April at CERN. These were the most precise measurements to date concerning the fluxes of protons, helium and the antiproton-to-proton ratio, extending at the same time the energy range of the PAMELA experiment. Most awaited were the results concerning the production of anti-matter, in particular the measurement of the anti-protons since the latter can be produced by the annihilation of Dark Matter particles which constitutes therefore a primary source. The conventional Standard Model production of anti-protons is through the collisions of high-energy cosmic rays with interstellar matter. This mechanism is  therefore a secondary production mechanism that constitutes an important background to the signal of new physics through Dark Matter detection. Previous estimates of this background predicted a steep decrease at high energy (hundreds of GeV) of the antiproton-to-proton ratio.

Read more: Refined background calculations for AMS02

   

The UGA Idex project pre-selected

investissements avenir
   logo uga


 Université de l’innovation

An important hurdle has been crossed on the way to achieve the goal of establishing the UGA, Université Grenoble Alpes, as a world class research and innovation university. The UGA is a conglomerate of universities and research institutions with a   multi-disciplinary training programme in Grenoble and in the Alps region. The French Ministry of Education and Research has announced that the Idex (Excellence Initiative) pre-project of UGA is one out of three pre-projects that has been selected among 7 other applications. This paves the way to the submission of the full project which will be reviewed by an international panel whose results will be made public in January 2016. In case of success this date will mark a new beginning for the new institution and will be a major boon for all the laboratories involved. For LAPTh this will reinforce our contribution to the Excellence Laboratory Initiative (Labex) Enigmass and build upon  our efforts in building a strong collaboration with the Grenoble laboratories. 

More details on the UGA Idex project can be found here (in French).

The project stands on excellent scientific foundations. For example, 1 out of  5 inhabitants in the Grenoble Alpes region are, in one way or the other, involved with research and innovation, see this short clip .

 

Lectures on Amplitudes and Symbols

monodromy giorgios

With the advent of the LHC and the need for ever increasing accuracy, techniques in loops calculations have witnessed tremendous progress borrowing from highly complex mathematical structures and improving and adapting these structures. A very recent development concerns  the use of symbols. Giorgios Papathanasiou will introduce some of  these concepts starting from an elementary exposition of how these objects appear from the integrals one encounters in the evaluation of scattering amplitudes beyond tree-level. There will be 4 lectures:

1: Analytic structure of scattering amplitudes and Feynman integrals. Algebraic and transcendental functions. Classical polylogarithms.

2: Multiple polylogarithms (MPL): Integral and Series representations. Shuffle and quasi-shuffle algebras.

3: The symbol map. Properties. Integrability condition. Application: Resolving identities among MPLs and simplifying expressions.

4: (Optional) Advanced topics: The Hopf algebra of MPLs and the coproduct. Bootstrapping amplitudes. Expanding the symbol.

   

Graspa 2015

Undergraduate Summer School in Particle and Astroparticle Physics of Annecy-le-Vieux, July 16-22 2015

The schoolgraspa 2015 aims at introducing Particle Physics and Astroparticle physics to 4th and advanced 3rd year physics students from anywhere in the world. The most recent research topics and results in these fields will be presented. The school consists of 4 days of lectures on LHC Physics, Neutrinos, Heavy Flavours, Astroparticle Physics and Gravitational Waves. Computational tools for these fields will also be introduced during a hands-on session. The students will be immersed in an international research atmosphere. They will be able to spend time and discuss at length with scientists working in the field.

Courses will be in English. No background knowledge on the topics covered beyond a popular science level is assumed. A strong background in Quantum Mechanics is expected, however.

 

A maximum of 30 students will be admitted.

 

PhysTeV Les Houches 2015

lh 2015

In a few weeks the high energy physics team will be going to Les Houches. We will be overseeing the 9th session of the LH PhysTeV. This session will coincide with the first beams at the LHC which will soon be  running at 13TeV.

The highlight of the 2015 Les Houches Edition is to take full advantage of the data that has been collected at the LHC so far and prepare for the future runs. The Workshop will devote particular attention to:(i) Higgs physics, and how it shapes our view on the mechanism of electroweak symmetry breaking; (ii) related searches for New Physics and (iii) progress in new techniques for the calculations and simulation of Standard Model processes. These activities will be conducted in close connection with the development and improvements of related theory tools, in particular of Monte-Carlo event generators.

The Workshop proper runs over one year, including two meetings in Les Houches in the month of June, and exchanges and collaborations before and after the meetings. The meetings in Les Houches will consist of two sessions:

Session I: 1-10 June 2015with emphasis on SM-related issues

Session II: 10-19 June 2015   with emphasis on New-Physics searches

Site of the LH2015 session   Wiki of LH2015

   

A course on Nonequilibrium Processes

kirone2Kirone Mallick from the Institut de Physique Théorique (IPhT) CEA Saclay is giving a set of lectures describing recent advances   in systems far from equilibrium. After a review of equilibrium thermodynamics, the lectures will introduce  the fascinating identities of Jarzinski and Crooks which quantify the transient violations of the second principle. This will be followed by the fluctuation theorem of Gallavoti-Cohen. Here is the exciting programme

1. Review of statistical physics: Equilibrium versus Non-equilibrium. Dynamics, Detailed Balance and Time-reversal.
2. Out of Equilibrium: Large Deviations, Generalized Detailed Balance and the Gallavotti-Cohen theorem.
3. Work Identities: the Jarzynski and Crooks identities.
4. The Asymmetric Exclusion Process: Exact Results
5. A unifying framework: the Macroscopic Fluctuation Theory.

 

A Possible solution to the Lithium problem?

poulin serpico

Big Bang Nucleosynthesis (BBN) is an admirable achievement of the standard cosmological model as it very precisely predicts the amount of the most abundant elements, in particular hydrogen and helium. On close inspection the picture is marred by a long standing and annoying problem. Though its abundance is extremely small, the standard predicted amount of lithium is  about a factor 3 larger than what observed in some metal-poor stars believed to trace the primordial abundance. Tweaking the theory of BBN to correct the lithium abundance affects that of the hydrogen or helium to an extent that this is ruled out by the Cosmic Microwave Background (CMB).

In a very recent paper, Pasquale D. Serpico and Vivian Poulin (LAPTh, CNRS) have shown that a loophole in the calculation  of the electromagnetic cascades re-opens the possibility of finding an easy way out to the old problem of the lithium abundance.

Read more: A Possible solution to the Lithium problem?

   

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