988 research outputs found
Sur des approximations d\u27indices de dissimilarité via les représentations euclidienne et hiérarchique
Sur les résultats de Blum en approximation et optimisation stochastiques multidimensionnelles
Structure géométrique des principaux indices de dissimilarité sur signes de présence-absence
Probing new physics in diphoton production with proton tagging at the Large Hadron Collider
The sensitivities to anomalous quartic photon couplings at the Large Hadron
Collider are estimated using diphoton production via photon fusion. The tagging
of the protons proves to be a very powerful tool to suppress the background and
unprecedented sensitivities down to \gev are obtained,
providing a new window on extra dimensions and strongly-interacting composite
states in the multi-TeV range. Generic contributions to quartic photon
couplings from charged and neutral particles with arbitrary spin are also
presented.Comment: 4 pages, 3 figure
Probing new physics in diphoton production with proton tagging at the Large Hadron Collider
Using atomic interference to probe atom-surface interaction
We show that atomic interference in the reflection from two suitably
polarized evanescent waves is sensitive to retardation effects in the
atom-surface interaction for specific experimental parameters. We study the
limit of short and long atomic de Broglie wavelength. The former case is
analyzed in the semiclassical approximation (Landau-Zener model). The latter
represents a quantum regime and is analyzed by solving numerically the
associated coupled Schroedinger equations. We consider a specific experimental
scheme and show the results for rubidium (short wavelength) and the much
lighter meta-stable helium atom (long wavelength). The merits of each case are
then discussed.Comment: 11 pages, including 6 figures, submitted to Phys. Rev. A, RevTeX
sourc
Setting limits on Effective Field Theories: the case of Dark Matter
The usage of Effective Field Theories (EFT) for LHC new physics searches is
receiving increasing attention. It is thus important to clarify all the aspects
related with the applicability of the EFT formalism in the LHC environment,
where the large available energy can produce reactions that overcome the
maximal range of validity, i.e. the cutoff, of the theory. We show that this
does forbid to set rigorous limits on the EFT parameter space through a
modified version of the ordinary binned likelihood hypothesis test, which we
design and validate. Our limit-setting strategy can be carried on in its
full-fledged form by the LHC experimental collaborations, or performed
externally to the collaborations, through the Simplified Likelihood approach,
by relying on certain approximations. We apply it to the recent CMS mono-jet
analysis and derive limits on a Dark Matter (DM) EFT model. DM is selected as a
case study because the limited reach on the DM production EFT Wilson
coefficient and the structure of the theory suggests that the cutoff might be
dangerously low, well within the LHC reach. However our strategy can also be
applied to EFT's parametrising the indirect effects of heavy new physics in the
Electroweak and Higgs sectors
Exploring the van der Waals Atom-Surface attraction in the nanometric range
The van der Waals atom-surface attraction, scaling as C3 z-3 for z the
atom-surface distance, is expected to be valid in the distance range 1-1000 nm,
covering 8-10 orders of magnitudes in the interaction energy. A Cs vapour
nanocell allows us to analyze the spectroscopic modifications induced by the
atom-surface attraction on the 6P3/2->6D5/2 transition. The measured C3 value
is found to be independent of the thickness in the explored range 40-130 nm,
and is in agreement with an elementary theoretical prediction. We also discuss
the specific interest of exploring short distances and large interaction
energy.Comment: to appear in Europhysics Letter
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