123 research outputs found
SmeftFR v3 -- Feynman rules generator for the Standard Model Effective Field Theory
We present version 3 of SmeftFR, a Mathematica package designed to generate
the Feynman rules for the Standard Model Effective Field Theory (SMEFT)
including the complete set of gauge invariant operators up to dimension-6 and
the complete set of bosonic operators of dimension-8. Feynman rules are
generated with the use of FeynRules package, directly in the physical (mass
eigenstates) basis for all fields. The complete set of interaction vertices can
be derived, including all or any chosen subset of SMEFT operators. As an
option, the user can also choose preferred gauge fixing, generating Feynman
rules in unitary or -gauges. The novel feature in version-3 of SmeftFR
is its ability to calculate SMEFT interactions consistently up to dimension-8
in EFT expansion (including quadratic dimension-6 terms) and express the
vertices directly in terms of user-defined set of input-parameters. The derived
Lagrangian in the mass basis can be exported in various formats supported by
FeynRules, such as UFO, FeynArts etc. Initialisation of numerical values of
Wilson coefficients of higher dimension operators is interfaced to WCxf format.
The package also includes a dedicated Latex generator allowing to print the
result in clear human-readable form. The SmeftFR v3 is publicly available at
www.fuw.edu.pl/smeft.Comment: 51 pages, version accepted for publication in Computer Physics
Communications. arXiv admin note: substantial text overlap with
arXiv:1904.0320
Real-time measurements of dissipative solitons in a mode-locked fiber laser
Dissipative solitons are remarkable localized states of a physical system
that arise from the dynamical balance between nonlinearity, dispersion and
environmental energy exchange. They are the most universal form of soliton that
can exist in nature, and are seen in far-from-equilibrium systems in many
fields including chemistry, biology, and physics. There has been particular
interest in studying their properties in mode-locked lasers producing
ultrashort light pulses, but experiments have been limited by the lack of
convenient measurement techniques able to track the soliton evolution in
real-time. Here, we use dispersive Fourier transform and time lens measurements
to simultaneously measure real-time spectral and temporal evolution of
dissipative solitons in a fiber laser as the turn-on dynamics pass through a
transient unstable regime with complex break-up and collision dynamics before
stabilizing to a regular mode-locked pulse train. Our measurements enable
reconstruction of the soliton amplitude and phase and calculation of the
corresponding complex-valued eigenvalue spectrum to provide further physical
insight. These findings are significant in showing how real-time measurements
can provide new perspectives into the ultrafast transient dynamics of complex
systems.Comment: See also M. Narhi, P. Ryczkowski, C. Billet, G. Genty, J. M. Dudley,
Ultrafast Simultaneous Real Time Spectral and Temporal Measurements of Fibre
Laser Modelocking Dynamics, 2017 Conference on Lasers and Electro-Optics
Europe & European Quantum Electronics Conference, paper EE-3.5 (2017
All-depth dispersion cancellation in spectral domain optical coherence tomography using numerical intensity correlations
In ultra-high resolution (UHR-) optical coherence tomography (OCT) group velocity dispersion (GVD) must be corrected for in order to approach the theoretical resolution limit. One approach promises not only compensation, but complete annihilation of even order dispersion effects, and that at all sample depths. This approach has hitherto been demonstrated with an experimentally demanding âbalanced detectionâ configuration based on using two detectors. We demonstrate intensity correlation (IC) OCT using a conventional spectral domain (SD) UHR-OCT system with a single detector. IC-SD-OCT configurations exhibit cross term ghost images and a reduced axial range, half of that of conventional SD-OCT. We demonstrate that both shortcomings can be removed by applying a generic artefact reduction algorithm and using analytic interferograms. We show the superiority of IC-SD-OCT compared to conventional SD-OCT by showing how IC-SD-OCT is able to image spatial structures behind a strongly dispersive silicon wafer. Finally, we question the resolution enhancement of 2â? that IC-SD-OCT is often believed to have compared to SD-OCT. We show that this is simply the effect of squaring the reflectivity profile as a natural result of processing the product of two intensity spectra instead of a single spectrum
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