2,714 research outputs found
Diffractively coupled resonators for interferometric applications and optical feedback to laser diodes
[no abstract
Jet production and measurements ofαsat HERA
Results on the measurements of the hadronic final state in e± p collisions by the H1 and ZEUS experiments at HERA are presented. These are measurements on the production of prompt photons in photoproduction, inclusive jet, dijet and trijet production in deep-inelatic scattering and on the search for QCD instantons. The jet production data is employed for the extraction of the strong coupling constant αs(MZ)
NNLO predictions for dijet production in diffractive DIS
Cross sections for inclusive dijet production in diffractive deep-inelastic
scattering are calculated for the first time in next-to-next-to-leading order
(NNLO) accuracy. These cross sections are compared to several HERA measurements
published by the H1 and ZEUS collaborations. We computed the total cross
sections, 49 single-differential and five double-differential distributions for
six HERA measurements. The NNLO corrections are found to be large and positive.
The normalization of the resulting predictions typically exceeds the data,
while the kinematical shape of the data is described better at NNLO than at
next-to-leading order (NLO). Our results use the currently available NLO
diffractive parton distributions, and the discrepancy in normalization
highlights the need for a consistent determination of these distributions at
NNLO accuracy
Michelson interferometer with diffractively-coupled arm resonators in second-order Littrow configuration
Michelson-type laser-interferometric gravitational-wave (GW) observatories
employ very high light powers as well as transmissively- coupled Fabry-Perot
arm resonators in order to realize high measurement sensitivities. Due to the
absorption in the transmissive optics, high powers lead to thermal lensing and
hence to thermal distortions of the laser beam profile, which sets a limit on
the maximal light power employable in GW observatories. Here, we propose and
realize a Michelson-type laser interferometer with arm resonators whose
coupling components are all-reflective second-order Littrow gratings. In
principle such gratings allow high finesse values of the resonators but avoid
bulk transmission of the laser light and thus the corresponding thermal beam
distortion. The gratings used have three diffraction orders, which leads to the
creation of a second signal port. We theoretically analyze the signal response
of the proposed topology and show that it is equivalent to a conventional
Michelson-type interferometer. In our proof-of-principle experiment we
generated phase-modulation signals inside the arm resonators and detected them
simultaneously at the two signal ports. The sum signal was shown to be
equivalent to a single-output-port Michelson interferometer with
transmissively-coupled arm cavities, taking into account optical loss. The
proposed and demonstrated topology is a possible approach for future
all-reflective GW observatory designs
Realization of a monolithic high-reflectivity cavity mirror from a single silicon crystal
We report on the first experimental realization of a high-reflectivity cavity
mirror that solely consists of a single silicon crystal. Since no material was
added to the crystal, the urgent problem of 'coating thermal noise' that
currently limits classical as well as quantum measurements is avoided. Our
mirror is based on a surface nanostructure that creates a resonant surface
waveguide. In full agreement with a rigorous model we realized a reflectivity
of (99.79+/-0.01)% at a wavelength of 1.55 {\mu}m, and achieved a cavity
finesse of 2784. We anticipate that our achievement will open the avenue to
next generation high-precision experiments targeting fundamental questions of
physics.Comment: Phys. Rev. Lett., accepte
Optimizing Observables with Machine Learning for Better Unfolding
Most measurements in particle and nuclear physics use matrix-based unfolding
algorithms to correct for detector effects. In nearly all cases, the observable
is defined analogously at the particle and detector level. We point out that
while the particle-level observable needs to be physically motivated to link
with theory, the detector-level need not be and can be optimized. We show that
using deep learning to define detector-level observables has the capability to
improve the measurement when combined with standard unfolding methods
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