scholarly journals Non-Perturbative Propagators in Quantum Gravity

Universe ◽  
2021 ◽  
Vol 7 (7) ◽  
pp. 216
Author(s):  
Benjamin Knorr ◽  
Marc Schiffer
Keyword(s):  
Quantum Gravity ◽  
Cross Sections ◽  
First Principles ◽  
Form Factors ◽  
Momentum Dependence ◽  
Scattering Cross ◽  
Group Methods ◽  
Gauge Fixing ◽  
Popov Ghost ◽  
Scattering Cross Sections

We employ non-perturbative renormalisation group methods to compute the full momentum dependence of propagators in quantum gravity in general dimensions. We disentangle all different graviton and Faddeev–Popov ghost modes and find qualitative differences in the momentum dependence of their propagators. This allows us to reconstruct the form factors that are quadratic in curvature from first principles, which enter physical observables like scattering cross sections. The results are qualitatively stable under variations of the gauge fixing choice.

Coherent and incoherent scattering of low-energy X-ray photons in the atomic region 13 ≤ Z ≤ 82

1996 ◽  
Vol 74 (1-2) ◽  
pp. 10-16 ◽  
Author(s):  
D. V. Rao ◽  
R. Cesareo ◽  
G. E. Gigante ◽  
D. V. Rao ◽  
G. E. Gigante
Keyword(s):  
Cross Sections ◽  
Detection System ◽  
Form Factors ◽  
Coherent Scattering ◽  
Incoherent Scattering ◽  
X Rays ◽  
Bremsstrahlung Radiation ◽  
X Ray ◽  
Scattering Cross ◽  
Scattering Cross Sections

Coherent- and incoherent-scattering cross sections for the elements Al, Cu, Y, In, Au, and Pb were measured using nearly monoenergetic unpolarized 35.86 and 39.96 keV X-ray beams with high-resolution Si (Li) detectors. Bremsstrahlung radiation from an X-ray tube was used to excite nearly monoenergetic X-rays in secondary targets. To improve the efficiency of the detection system the excitation source, detector, and the target assembly were placed in a vacuum chamber and a pressure of 10−2 mbar was maintained throughout the measurements. This system considerably reduced the background and scattering effects and improved the monochromacy. Experimental coherent-scattering cross sections are compared with the normalized integrated coherent-scattering cross sections calculated using the relativistic, nonrelativistic, and relativistic-modified form factors. Experimental incoherent-scattering cross sections are compared with the theoretical values, calculated using the nonrelativistic incoherent-scattering function. Good correspondence is observed between experimental and theoretical values in the given energy region.

scholarly journals Recasting direct detection limits within micrOMEGAs and implication for non-standard dark matter scenarios

2021 ◽  
Vol 81 (3) ◽  
Author(s):  
G. Bélanger ◽  
A. Mjallal ◽  
A. Pukhov
Keyword(s):  
Dark Matter ◽  
Elastic Scattering ◽  
Velocity Distribution ◽  
Cross Sections ◽  
Direct Detection ◽  
Cosmological Parameters ◽  
Form Factors ◽  
Scattering Cross ◽  
Upper Limits ◽  
Scattering Cross Sections

AbstractDirect detection experiments obtain 90% upper limits on the elastic scattering cross sections of dark matter with nucleons assuming point-like interactions and standard astrophysical and cosmological parameters. In this paper we provide a recasting of the limits from XENON1T, PICO-60, CRESST-III and DarkSide-50 and include them in micrOMEGAs. The code can then be used to directly impose constraints from these experiments on generic dark matter models under different assumptions about the DM velocity distribution or on the nucleus form factors. Moreover, new limits on the elastic scattering cross sections can be obtained in the presence of a light t-channel mediator or of millicharged particles.

Atomic form factors, incoherent scattering functions, and photon scattering cross sections

1975 ◽  
Vol 4 (3) ◽  
pp. 471-538 ◽  
Author(s):  
J. H. Hubbell ◽  
Wm. J. Veigele ◽  
E. A. Briggs ◽  
R. T. Brown ◽  
D. T. Cromer ◽  
...  
Keyword(s):  
Cross Sections ◽  
Form Factors ◽  
Incoherent Scattering ◽  
Photon Scattering ◽  
Scattering Cross ◽  
Scattering Cross Sections

scholarly journals Erratum: Atomic Form Factors, Incoherent Scattering Functions, and Photon Scattering Cross Sections

1977 ◽  
Vol 6 (2) ◽  
pp. 615-616 ◽  
Author(s):  
J. H. Hubbell ◽  
Wm. J. Veigele ◽  
E. A. Briggs ◽  
R. T. Brown ◽  
D. T. Cromer ◽  
...  
Keyword(s):  
Cross Sections ◽  
Form Factors ◽  
Incoherent Scattering ◽  
Photon Scattering ◽  
Scattering Cross ◽  
Scattering Cross Sections

Absolute inner-shell cross section determination for EELS analysis

1988 ◽  
Vol 46 ◽  
pp. 534-535
Author(s):  
P.A. Crozier
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Absolute Cross Section ◽  
Specimen Thickness ◽  
Mass Thickness ◽  
Scattering Cross ◽  
Before And After ◽  
Estimated Error ◽  
Scattering Cross Sections ◽  
Electron Microscopist

Absolute inelastic scattering cross sections or mean free paths are often used in EELS analysis for determining elemental concentrations and specimen thickness. In most instances, theoretical values must be used because there have been few attempts to determine experimental scattering cross sections from solids under the conditions of interest to electron microscopist. In addition to providing data for spectral quantitation, absolute cross section measurements yields useful information on many of the approximations which are frequently involved in EELS analysis procedures. In this paper, experimental cross sections are presented for some inner-shell edges of Al, Cu, Ag and Au.Uniform thin films of the previously mentioned materials were prepared by vacuum evaporation onto microscope cover slips. The cover slips were weighed before and after evaporation to determine the mass thickness of the films. The estimated error in this method of determining mass thickness was ±7 x 107g/cm2. The films were floated off in water and mounted on Cu grids.

scholarly journals Towards fully nonperturbative computations of inelastic ℓN scattering cross sections from lattice QCD

2020 ◽  
Vol 102 (11) ◽  
Author(s):  
Hidenori Fukaya ◽  
Shoji Hashimoto ◽  
Takashi Kaneko ◽  
Hiroshi Ohki
Keyword(s):  
Lattice Qcd ◽  
Cross Sections ◽  
Scattering Cross ◽  
Scattering Cross Sections
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