11 research outputs found
Hidden cusps
International audienceThis paper investigates a situation pointed out in a recent paper, in which a non-singular change of assembly mode of a planar 2-RPR-PR parallel manipulator was realized by encircling a point of multiplicity 4. It is shown that this situation is, in fact, a non-generic one and gives rise to cusps under a small perturbation. Furthermore , we show that, for a large class of singularities of multiplicity 4, there are only two types of stable singularities occurring in a small perturbation: these two types are given by the complex square mapping and the quarto mapping. Incidentally , this paper confirms the fact that, generically, a local non-singular change of solution must be accomplished by encircling a cusp point
Evolution and Dynamics of Cusped Light-Like Wilson Loops in Loop Space
We discuss the possible relation between the singular structure of TMDs on
the light-cone and the geometrical behaviour of rectangular Wilson loops.Comment: Proceedings for Diffraction 2012, Lanzarote, Spain. 5 pages, 2
figure
Evolution and dynamics of cusped light-like Wilson loops
We discuss the possible relation between the singular structure of TMDs on
the light-cone and the geometrical behaviour of rectangular Wilson loops.Comment: 6 pages, proceedings for the 3rd Workshop on the QCD Structure of the
Nucleon (QCD-N'12
Highlights and Conclusions of the Chalonge Meudon Workshop Dark Matter in the Universe
The CIAS Chalonge Workshop `Dark Matter in the Universe and Universal
Properties of Galaxies: Theory and Observations', was held at the Meudon
Ch^ateau of Observatoire de Paris on 8-11 June 2010. The Workshop approached DM
in a fourfold way: astronomical observations of DM structures (galaxy
properties, halos, rotation curves and density profiles), DM numerical
simulations (with and without baryons), theoretical astrophysics and cosmology
(kinetic theory, Boltzmann-Vlasov evolution), astroparticle physics. Peter
Biermann, Alfonso Cavaliere, Hector J. de Vega, Gianfranco Gentile, Chandra
Jog, Andrea Lapi, Paolo Salucci, Norma G. Sanchez, Pasquale Serpico, Rainer
Stiele, Janine van Eymeren and Markus Weber present here their highlights of
the Workshop. The summary and conclusions by H. J. de Vega and N. G. Sanchez
stress among other points the growing evidence that DM particles have a mass in
the keV scale and that those keV scale particles naturally produce the small
scale structures observed in galaxies. Wimps (DM particles heavier than 1 GeV)
are strongly disfavoured combining theory with galaxy astronomical
observations. Peter Biermann presents his live minutes of the Workshop and
concludes that a right-handed sterile neutrino of mass of a few keV is the most
interesting DM candidate. Photos of the Workshop are included.Comment: 41 pages, 10 figures, 3 photos. Problem in group photo fixe
Highlights and Conclusions of the Chalonge 14th Paris Cosmology Colloquium 2010: `The Standard Model of the Universe: Theory and Observations'
The Chalonge 14th Paris Cosmology Colloquium was held on 22-24 July 2010 in
Paris Observatory on the Standard Model of the Universe: News from WMAP7,
BICEP, QUAD, SPT, AMI, ACT, Planck, QUIJOTE and Herschel; dark matter (DM)
searches and galactic observations; related theory and simulations. %aiming
synthesis, progress and clarification. P Biermann, D Boyanovsky, A Cooray, C
Destri, H de Vega, G Gilmore, S Gottlober, E Komatsu, S McGaugh, A Lasenby, R
Rebolo, P Salucci, N Sanchez and A Tikhonov present here their highlights of
the Colloquium. Inflection points emerged: LambdaWDM (Warm DM) emerges
impressively over LambdaCDM whose galactic scale problems are ever-increasing.
Summary and conclusions by H. J. de Vega, M. C. Falvella and N. G. Sanchez
stress among other points: (i) Primordial CMB gaussianity is confirmed.
Inflation effective theory predicts a tensor to scalar ratio 0.05-0.04 at
reach/border line of next CMB observations, early fast-roll inflation provides
lowest multipoles depression. SZ amplitudes are smaller than expected: CMB and
X-ray data agree but intracluster models need revision and relaxed/non-relaxed
clusters distinction. (ii) cosmic ray positron excess is explained naturally by
astrophysical processes, annihilating/decaying dark matter needs growing
tailoring. (iii) Cored (non cusped) DM halos and warm (keV scale mass) DM are
increasingly favored from theory and observations, naturally producing observed
small scale structures, wimps turn strongly disfavoured. LambdaWDM 1 keV
simulations well reproduce observations. Evidence that LambdaCDM does not work
at small scales is staggering. P Biermann presents his live minutes of the
Colloquium and concludes that a keV sterile neutrino is the most interesting DM
candidate. Photos of the Colloquium are included.Comment: 58 pages, 20 figures. Three contributions added: G. Gilmore, S.
Gottlober and E. Komats
Towards the Chalonge 17th Paris Cosmology Colloquium 2013: highlights and conclusions of the Chalonge 16th Paris Cosmology Colloquium 2012
LWDM (Warm Dark Matter) is progressing impressively.The galactic scale crisis
and decline of LCDM+baryons are staggering. The 16th Paris Chalonge Colloquium
2012 combined real cosmological/astrophysical data and hard theory predictive
approach in the LWDM Standard Model. News and reviews from
ACT,WMAP,SPT,QUIET,Planck,Herschel,JWST,UFFO,KATRIN and MARE experiments;
astrophysics, particle and nuclear physics WDM searches, galactic observations,
related theory and simulations, with the aim of synthesis and clarification.
Here highlights by P Biermann, C Burigana, C Conselice, A Cooray, H de Vega, C
Giunti & M Laveder, J Kormendi & K Freeman, E Ma, J Mather, L Page, G Smoot, N
Sanchez. Summary and conclusions by de Vega, Falvella and Sanchez. Data confirm
primordial CMB gaussianity. Effective (Ginsburg-Landau) Inflation theory
predicts r about 0.04-0.05, negligeable running of ns, the inflation energy
scale (GUT scale) and the set of CMB observables in agreement with the data.
WMAP9 and Planck measurements are compatible with one or two Majorana sterile
neutrinos in the eV mass scale. Cored (non cusped) DM halos and keV WDM are
strongly favored by theory and observations, Wimps are strongly disfavoured.
LambdaCDM with baryons do not work at small scales. Inside galaxy cores,
quantum WDM effects are important. Quantum WDM calculations (Thomas-Fermi)
provide galaxy masses, velocity dispersions and cored profiles and their sizes
in agreement with observations. A WDM fermion of about 2 keV naturally
reproduces galaxy, large scale and cosmological observations. WDM keV particles
deserve dedicated astronomical and laboratory searches, theoretical work and
numerical simulations. KATRIN can be adapted to look to keV scale sterile
neutrinos. It will be a fantastic discovery to detect dark matter in beta
decay. Photos of the Colloquium are includedComment: 58 pages, 15 figures. arXiv admin note: substantial text overlap with
arXiv:1203.3562, arXiv:1305.7452, arXiv:1009.3494, arXiv:1304.075
Towards the Chalonge 16th Paris Cosmology Colloquium 2012: Highlights and Conclusions of the Chalonge 15th Paris Cosmology Colloquium 2011
The Chalonge 15th Paris Cosmology Colloquium 2011 was held on 20-22 July in
the historic Paris Observatory's Perrault building, in the Chalonge School
spirit combining real cosmological/astrophysical data and hard theory
predictive approach connected to them in the Warm Dark Matter Standard Model of
the Universe: News and reviews from Herschel, QUIET, Atacama Cosmology
Telescope (ACT), South Pole Telescole (SPT), Planck, PIXIE, the JWST, UFFO,
KATRIN and MARE experiments; astrophysics, particle and nuclear physics warm
dark matter (DM) searches and galactic observations, related theory and
simulations, with the aim of synthesis, progress and clarification. Philippe
Andre, Peter Biermann, Pasquale Blasi, Daniel Boyanovsky, Carlo Burigana,
Hector de Vega, Joanna Dunkley, Gerry Gilmore, Alexander Kashlinsky, Alan
Kogut, Anthony Lasenby, John Mather, Norma Sanchez, Alexei Smirnov, Sylvaine
Turck-Chieze present here their highlights of the Colloquium. Ayuki Kamada and
Sinziana Paduroiu present here their poster highlights. LambdaWDM (Warm Dark
Matter) is progressing impressively over LambdaCDM whose galactic scale crisis
and decline are staggering. The International School Daniel Chalonge issued an
statement of strong support to the James Webb Space Telescope (JSWT). The
Daniel Chalonge Medal 2011 was awarded to John C. Mather, Science PI of the
JWST. Summary and conclusions are presented by H. J. de Vega, M. C. Falvella
and N. G. Sanchez. Overall, LambdaWDM and keV scale DM particles deserve
dedicated astronomical and laboratory experimental searches, theoretical work
and simulations. KATRIN experiment in the future could perhaps adapt its set-up
to look to keV scale sterile neutrinos. It will be a a fantastic discovery to
detect dark matter in a beta decay. Photos of the Colloquium are included.
(Abridged)Comment: 65 pages, 21 figure
Warm dark matter in the galaxies:theoretical and observational progresses. Highlights and conclusions of the chalonge meudon workshop 2011
Warm Dark Matter (WDM) research is progressing fast, the subject is new and
WDM essentially works, naturally reproducing the astronomical observations over
all scales: small (galactic) and large (cosmological) scales (LambdaWDM).
Evidence that Cold Dark Matter (LambdaCDM) and its proposed tailored cures do
not work at small scales is staggering. Fedor Bezrukov, Pier-Stefano
Corasaniti, Hector J. de Vega, Stefano Ettori, Frederic Hessmann, Ayuki Kamada,
Marco Lombardi, Alexander Merle, Christian Moni Bidin, Angelo Nucciotti on
behalf of the MARE collaboration, Sinziana Paduroiu, Henri Plana, Norma
Sanchez, Patrick Valageas, Shun Zhou present here their highlights of the
Workshop. LambdaWDM simulations with keV particles remarkably reproduce the
observations, small and large structures and velocity functions. Cored DM halos
and WDM are clearly determined from theory and astronomical observations, they
naturally produce the observed structures at all scales. keV sterile neutrinos
are the leading candidates, they naturally appear extensions of the standard
model of particle physics. Astrophysical constraints including Lyman alpha
bounds put its mass in the range 1< m <13 keV. Predictions for EUCLID and
PLANCK have been presented. MARE and an adapted KATRIN experiment could detect
a keV sterile neutrino. It will be a fantastic discovery to detect dark matter
in a beta decay. A formidable WDM work to perform is ahead of us, these
highlights point out some relevant research directions to put the effort.
Photos of the Workshop are included (Abridged).Comment: 48 pages, 24 figure