Search results for "scattering [hadron]"
showing 10 items of 232 documents
Frequency-dependent relaxation rate in superconductingYBa2Cu3O6+δ
2000
The submillimeter-wave $3 {\mathrm{cm}}^{\ensuremath{-}1}l\ensuremath{\nu}l40 {\mathrm{cm}}^{\ensuremath{-}1}$ complex conductivity of the reduced ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{6+\ensuremath{\delta}}$ film ${(T}_{C}=56.5 \mathrm{K})$ was investigated for temperatures $4 \mathrm{K}lTl300 \mathrm{K}$ and compared to the properties of the same film in the optimally doped state. The frequency dependence of the effective quasiparticle scattering rate $1/{\ensuremath{\tau}}^{*}(\ensuremath{\nu})$ was extracted from the spectra. $1/{\ensuremath{\tau}}^{*}$ is shown to be frequency independent at low frequencies and high temperatures. A gradual change to $1/{\ensuremath{\tau}}^{…
The loop-tree duality at work
2014
We review the recent developments of the loop-tree duality method, focussing our discussion on analysing the singular behaviour of the loop integrand of the dual representation of one-loop integrals and scattering amplitudes. We show that within the loop-tree duality method there is a partial cancellation of singularities at the integrand level among the different components of the corresponding dual representation. The remaining threshold and infrared singularities are restricted to a finite region of the loop momentum space, which is of the size of the external momenta and can be mapped to the phase-space of real corrections to cancel the soft and collinear divergences.
Measurement of the Coherent Neutron Scattering Length of (3) He.
2005
By means of neutron interferometry the s-wave neutron scattering length of the (3)He nucleus was re-measured at the Institut Laue-Langevin (ILL). Using a skew symmetrical perfect crystal Si-interferometer and a linear twin chamber cell, false phase shifts due to sample misalignment were reduced to a negligible level. Simulation calculations suggest an asymmetrically alternating measuring sequence in order to compensate for systematic errors caused by thermal phase drifts. There is evidence in the experiment's data that this procedure is indeed effective. The neutron refractive index in terms of Sears' exact expression for the scattering amplitude has been analyzed in order to evaluate the m…
Column aerosol optical properties and aerosol radiative forcing during a serious haze-fog month over North China Plain in 2013 based on ground-based …
2014
In January 2013, North China Plain experienced several serious haze events. Cimel sunphotometer measurements at seven sites over rural, suburban and urban regions of North China Plain from 1 to 30 January 2013 were used to further our understanding of spatial-temporal variation of aerosol optical parameters and aerosol radiative forcing (ARF). It was found that Aerosol Optical Depth at 500 nm (AOD500 nm) during non-pollution periods at all stations was lower than 0.30 and increased significantly to greater than 1.00 as pollution events developed. The Angstrom exponent (Alpha) was larger than 0.80 for all stations most of the time. AOD500 nm averages increased from north to south during both…
Wide Angle Compton Scattering within the SCET factorization Framework
2016
Existing data for the electromagnetic proton form factors and for the cross section of the wide angle Compton scattering (WACS) show that the hard two-gluon exchange mechanism (collinear factorization) is still not applicable in the kinematical region where Mandelstam variables s ~ −t ~ −u are about few GeV2 . On the other hand these observables can be described in phenomenological models where spectator quarks are soft which assumes a large contribution due to the soft-overlap mechanism. It turns out that the simple QCD factorization picture is not complete and must also include the soft-overlap contribution which can be described as a certain matrix element in the soft collinear effective…
Odderon Exchange from Elastic Scattering Differences between pp and pp¯ Data at 1.96 TeV and from pp Forward Scattering Measurements
2021
We describe an analysis comparing the p p ¯ elastic cross section as measured by the D0 Collaboration at a center-of-mass energy of 1.96 TeV to that in p p collisions as measured by the TOTEM Collaboration at 2.76, 7, 8, and 13 TeV using a model-independent approach. The TOTEM cross sections, extrapolated to a center-of-mass energy of s = 1.96 TeV , are compared with the D0 measurement in the region of the diffractive minimum and the second maximum of the p p cross section. The two data sets disagree at the 3.4 σ level and thus provide evidence for the t -channel exchange of a colorless, C -odd gluonic compound, also known as the odderon. We combine these results with a TOTEM analysis of th…
Determination of s - and p -wave I = 1/2 Kπ scattering amplitudes in N f = 2 + 1 lattice QCD
2018
Nuclear physics 932, 29 - 51 (2018). doi:10.1016/j.nuclphysb.2018.05.008
Linear Wave Equations and Effective Lagrangians for Wigner Supermultiplets
1995
The relevance of the contracted SU(4) group as a symmetry group of the pion nucleon scattering amplitudes in the large $N_c$ limit of QCD raises the problem on the construction of effective Lagrangians for SU(4) supermultiplets. In the present study we suggest effective Lagrangians for selfconjugate representations of SU(4) in exploiting isomorphism between so(6) and ist universal covering su(4). The model can be viewed as an extension of the linear $\sigma$ model with SO(6) symmetry in place of SO(4) and generalizes the concept of the linear wave equations for particles with arbitrary spin. We show that the vector representation of SU(4) reduces on the SO(4) level to a complexified quatern…
Gauge invariance of the deeply virtual Compton scattering amplitude
2000
We analyze in detail the problem of gauge invariance of the deeply virtual Compton scattering (DVCS) amplitude. Using twist-3 one-gluon exchange diagram contributions and the QCD equations of motion, we derive the general gauge invariant expression of the DVCS amplitude on a (pseudo)scalar particle (pion, ${\mathrm{He}}^{4}).$ Similarly to the case of deep inelastic scattering, the amplitude does not depend on the twist-3 quark-gluon correlations at the Born level. The contribution of the derived amplitude to the single-spin asymmetry with longitudinally polarized lepton is calculated.
N/Ddescription of two meson amplitudes and chiral symmetry
1998
The most general structure of an elastic partial wave amplitude when the unphysical cuts are neglected is deduced in terms of the N/D method. This result is then matched to lowest order, ${\mathcal{O}}(p^2)$, Chiral Perturbation Theory($\chi$PT) and to the exchange (consistent with chiral symmetry) of resonances in the s-channel. The extension of the method to coupled channels is also given. Making use of the former formalism, the $\pi\pi$ and $K\pi$(I=1/2) P-wave scattering amplitudes are described without free parameters when taking into account relations coming from the 1/$N_c$ expansion and unitarity. Next, the scalar sector is studied and good agreement with experiment up to $\sqrt{s}=…