scholarly journals Revisiting $$\gamma ^*\rightarrow \gamma \pi ^0\eta $$ near the $$\phi (1020)$$ using analyticity and the left-cut structure

2021 ◽  
Vol 81 (11) ◽  
Author(s):  
B. Moussallam
Keyword(s):  
Form Factors ◽  
Scattering Data ◽  
Theoretical Modelling ◽  
Effective Theory ◽  
Data Sets ◽  
Scalar Form ◽  
Left Hand ◽  
Soft Pion ◽  
Light Vector ◽  
Kloe Collaboration

AbstractAmplitudes of the form $$\gamma ^*(q^2)\rightarrow \gamma P_1P_2$$ γ ∗ ( q 2 ) → γ P 1 P 2 appear as sub-processes in the computation of the muon $$g-2$$ g - 2 . We test a proposed theoretical modelling against very precise experimental measurements by the KLOE collaboration at $$q^2=m^2_\phi $$ q 2 = m ϕ 2 . Starting from an exact, parameter-free dispersive representation for the S-wave satisfying QCD asymptotic constraints and Low’s soft photon theorem we derive, in an effective theory spirit, a two-channel Omnès integral representation which involves two subtraction parameters. The discontinuities along the left-hand cuts which, for timelike virtualities, extend both on the real axis and into the complex plane are saturated by the contributions from the light vector mesons. In the case of $$P_1P_2=\pi \eta $$ P 1 P 2 = π η , we show that a very good fit of the KLOE data can be achieved with two real parameters, using a T-matrix previously determined from $$\gamma \gamma $$ γ γ scattering data. This indicates a good compatibility between the two data sets and confirms the validity of the T-matrix. The resulting amplitude is also found to be compatible with the chiral soft pion theorem. Applications to the $$I=1$$ I = 1 scalar form factors and to the $$a_0(980)$$ a 0 ( 980 ) resonance complex pole are presented.

BACKWARD ANGLE STRUCTURE IN THE 20Ne+28Si QUASIELASTIC SCATTERING

2013 ◽  
Vol 22 (10) ◽  
pp. 1350073 ◽  
Author(s):  
O. SGOUROS ◽  
V. SOUKERAS ◽  
A. PAKOU ◽  
N. PATRONIS ◽  
K. ZERVA ◽  
...  
Keyword(s):  
Cross Sections ◽  
Form Factors ◽  
Scattering Data ◽  
Data Sets ◽  
Quasielastic Scattering ◽  
Particle Form ◽  
Reaction Channels ◽  
Reasonable Description ◽  
Optical Model Analysis ◽  
Backward Angle

New data for the quasielastic scattering of 20 Ne from a 28 Si target at incident energies of 42.5 MeV and 52.3 MeV and for the 28 Si (20 Ne , 24 Mg )24 Mg , 28 Si (20 Ne , 16 O )32S and 28 Si (20 Ne , 12 C )36 Ar transfer reactions at 52.3 MeV are reported. Oscillations are observed in the backward angle quasielastic scattering data at 52.3 MeV and the 28 Si (20 Ne , 12 C )36 Ar transfer cross-sections are of the same magnitude as those for single-α stripping. Coupled reaction channels (CRC) calculations are unable to describe either the quasielastic or the 28 Si (20 Ne , 12 C )36 Ar transfer data assuming a sequential α transfer process with α-particle form factors from the literature. The addition of direct 8 Be cluster transfer can provide a reasonable description of both data sets, but only with much larger spectroscopic factors than suggested by simple structure calculations or the large 8 Be emission thresholds of 20 Ne , 28 Si and 36 Ar , suggesting that the observed structure is of resonance-like origin. An optical model analysis of the quasielastic scattering data is also reported.

scholarly journals Constraints on light vector mediators through coherent elastic neutrino nucleus scattering data from COHERENT

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
M. Cadeddu ◽  
N. Cargioli ◽  
F. Dordei ◽  
C. Giunti ◽  
Y. F. Li ◽  
...  
Keyword(s):  
Anomalous Magnetic Moment ◽  
Solar Neutrino ◽  
Recent Observation ◽  
Cesium Iodide ◽  
Scattering Data ◽  
Data Sets ◽  
Fixed Target ◽  
Parameter Region ◽  
Light Vector ◽  
Nucleus Scattering

Abstract We present new constraints on three different models, the so-called universal, B − L and Lμ− Lτ models, involving a yet to be observed light vector Z′ mediator, by exploiting the recent observation of coherent elastic neutrino-nucleus scattering (CEνNS) in argon and cesium-iodide performed by the COHERENT Collaboration. We compare the results obtained from a combination of the above data sets with the limits derived from searches in fixed target, accelerator, solar neutrino and reactor CEνNS experiments, and with the parameter region that could explain the anomalous magnetic moment of the muon. We show that for the universal and the B − L models, the COHERENT data allow us to put stringent limits in the light vector mediator mass, MZ′, and coupling, gZ′, parameter space.

scholarly journals Consistent treatment of rapidity divergence in soft-collinear effective theory

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Junegone Chay ◽  
Chul Kim
Keyword(s):  
Heavy Quark ◽  
Soft Mode ◽  
Form Factors ◽  
Effective Theory ◽  
Large Rapidity ◽  
Soft Modes ◽  
Heavy Quark Mass ◽  
Soft Collinear Effective Theory ◽  
Matching Procedure ◽  
Consistent Treatment

Abstract In soft-collinear effective theory, we analyze the structure of rapidity divergence due to the collinear and soft modes residing in disparate phase spaces. The idea of an effective theory is applied to a system of collinear modes with large rapidity and soft modes with small rapidity. The large-rapidity (collinear) modes are integrated out to obtain the effective theory for the small-rapidity (soft) modes. The full SCET with the collinear and soft modes should be matched onto the soft theory at the rapidity boundary, and the matching procedure becomes exactly the zero-bin subtraction. The large-rapidity region is out of reach for the soft mode, which results in the rapidity divergence. The rapidity divergence in the collinear sector comes from the zero-bin subtraction, which ensures the cancellation of the rapidity divergences from the soft and collinear sectors. In order to treat the rapidity divergence, we construct the rapidity regulators consistently for all the modes. They are generalized by assigning independent rapidity scales for different collinear directions. The soft regulator incorporates the correct directional dependence when the innate collinear directions are not back-to-back, which is discussed in the N-jet operator. As an application, we consider the Sudakov form factor for the back-to-back collinear current and the soft-collinear current, where the soft rapidity regulator for a soft quark is developed. We extend the analysis to the boosted heavy quark sector and exploit the delicacy with the presence of the heavy quark mass. We present the resummed results of large logarithms in the form factors for various currents with the light and the heavy quarks, employing the renormalization group evolution on the renormalization and the rapidity scales.

A batch-wise non-linear fitting and analysis tool for treating large X-ray diffraction data sets

2006 ◽  
Vol 39 (2) ◽  
pp. 262-266 ◽  
Author(s):  
R. J. Davies
Keyword(s):  
Diffraction Data ◽  
Operation Mode ◽  
Large Data ◽  
Scattering Data ◽  
Data Sets ◽  
Analysis Tool ◽  
Data Set ◽  
X Ray ◽  
Linear Fitting ◽  
Non Linear

Synchrotron sources offer high-brilliance X-ray beams which are ideal for spatially and time-resolved studies. Large amounts of wide- and small-angle X-ray scattering data can now be generated rapidly, for example, during routine scanning experiments. Consequently, the analysis of the large data sets produced has become a complex and pressing issue. Even relatively simple analyses become difficult when a single data set can contain many thousands of individual diffraction patterns. This article reports on a new software application for the automated analysis of scattering intensity profiles. It is capable of batch-processing thousands of individual data files without user intervention. Diffraction data can be fitted using a combination of background functions and non-linear peak functions. To compliment the batch-wise operation mode, the software includes several specialist algorithms to ensure that the results obtained are reliable. These include peak-tracking, artefact removal, function elimination and spread-estimate fitting. Furthermore, as well as non-linear fitting, the software can calculate integrated intensities and selected orientation parameters.

New analysis of the low-energy π±p differential cross-sections of the CHAOS Collaboration

2015 ◽  
Vol 24 (07) ◽  
pp. 1550050 ◽  
Author(s):  
E. Matsinos ◽  
G. Rasche
Keyword(s):  
Experimental Data ◽  
Cross Sections ◽  
Differential Cross ◽  
Form Factors ◽  
Partial Wave Analysis ◽  
Meson Mass ◽  
Data Sets ◽  
Differential Cross Sections ◽  
Pion Nucleon ◽  
Meson Factory

In a previous paper, we reported the results of a partial-wave analysis (PWA) of the pion–nucleon (πN) differential cross-sections (DCSs) of the CHAOS Collaboration and came to the conclusion that the angular distribution of their π+p data sets is incompatible with the rest of the modern (meson factory) database. The present work, re-addressing this issue, has been instigated by a number of recent improvements in our analysis, namely regarding the inclusion of the theoretical uncertainties when investigating the reproduction of experimental data sets on the basis of a given "theoretical" solution, modifications in the parametrization of the form factors of the proton and of the pion entering the electromagnetic part of the πN amplitude, and the inclusion of the effects of the variation of the σ-meson mass when fitting the ETH model of the πN interaction to the experimental data. The new analysis of the CHAOS DCSs confirms our earlier conclusions and casts doubt on the value for the πN Σ term, which Stahov, Clement and Wagner have extracted from these data.

Prevalence Rates for Medical Problems among Flautists: A Comparison of the UNT-Musician Health Survey and the Flute Health Survey

2001 ◽  
Vol 16 (3) ◽  
pp. 99-101
Author(s):  
Cari Spence
Keyword(s):  
Health Survey ◽  
Sleep Disturbances ◽  
Data Sets ◽  
Prevalence Rates ◽  
Medical Problems ◽  
North Texas ◽  
University Of North Texas ◽  
Left Hand ◽  
Significant Difference ◽  
The University

The purpose of this study was to identify prevalence rates of medical problems among flautists. The Flute Health Survey (FHS), a questionnaire with items regarding musculoskeletal and nonmusculoskeletal problems, was distributed at the 1999 National Flute Association annual meeting (n = 40). This questionnaire was pilot tested at the 1999 Texas Flute Festival, which is hosted by the Texas Flute Society. The University of North Texas has posted on the Internet a similar questionnaire regarding the medical problems of all musicians. Responses from the University of North Texas Musician Health Survey (UNT-MHS) were filtered to include only those respondents who denoted flute as their primary instruments (n = 328). Data sets from both surveys were then processed using comparative statistics. Findings show that there was no significant difference between the demographics of the two populations. Only one musculoskeletal site, the left hand, was found to be statistically significant between the two groups. Four nonmusculoskeletal items, depression, earache, headache, and sleep disturbances, were found to be different between the two groups. The overall findings of this comparison show that there are many medical problems facing the flute playing community. Further investigation and observations of this population are necessary.

scholarly journals Ultrafast calculation of diffuse scattering from atomistic models

2019 ◽  
Vol 75 (1) ◽  
pp. 14-24 ◽  
Author(s):  
Joseph A. M. Paddison
Keyword(s):  
Diffuse Scattering ◽  
Large Data ◽  
Large Data Sets ◽  
Scattering Data ◽  
Frequency Noise ◽  
Data Sets ◽  
Fast Method ◽  
Crystalline Materials ◽  
Atomistic Models ◽  
Dynamics Simulations

Diffuse scattering is a rich source of information about disorder in crystalline materials, which can be modelled using atomistic techniques such as Monte Carlo and molecular dynamics simulations. Modern X-ray and neutron scattering instruments can rapidly measure large volumes of diffuse-scattering data. Unfortunately, current algorithms for atomistic diffuse-scattering calculations are too slow to model large data sets completely, because the fast Fourier transform (FFT) algorithm has long been considered unsuitable for such calculations [Butler & Welberry (1992). J. Appl. Cryst. 25, 391–399]. Here, a new approach is presented for ultrafast calculation of atomistic diffuse-scattering patterns. It is shown that the FFT can actually be used to perform such calculations rapidly, and that a fast method based on sampling theory can be used to reduce high-frequency noise in the calculations. These algorithms are benchmarked using realistic examples of compositional, magnetic and displacive disorder. They accelerate the calculations by a factor of at least 102, making refinement of atomistic models to large diffuse-scattering volumes practical.

Comparison of iterative desmearing procedures for one-dimensional small-angle scattering data

2011 ◽  
Vol 44 (1) ◽  
pp. 32-42 ◽  
Author(s):  
Thomas Vad ◽  
Wiebke F. C. Sager
Keyword(s):  
Small Angle ◽  
Incident Beam ◽  
Scattering Data ◽  
Data Sets ◽  
Convergence Criteria ◽  
Small Momentum Transfer ◽  
One Dimensional ◽  
Noise Filter ◽  
Large Numbers ◽  
Angle Scattering

Two simple iterative desmearing procedures – the Lake algorithm and the Van Cittert method – have been investigated by introducing different convergence criteria using both synthetic and experimental small-angle neutron scattering data. Implementing appropriate convergence criteria resulted in stable and reliable solutions in correcting resolution errors originating from instrumental smearing,i.e.finite collimation and polychromaticity of the incident beam. Deviations at small momentum transfer for concentrated ensembles of spheres encountered in earlier studies are not observed. Amplification of statistical errors can be reduced by applying a noise filter after desmearing. In most cases investigated, the modified Lake algorithm yields better results with a significantly smaller number of iterations and is, therefore, suitable for automated desmearing of large numbers of data sets.

FitGISAXS: software package for modelling and analysis of GISAXS data using IGOR Pro

2010 ◽  
Vol 43 (4) ◽  
pp. 929-936 ◽  
Author(s):  
David Babonneau
Keyword(s):  
Software Package ◽  
Form Factors ◽  
Grazing Incidence ◽  
Three Dimensions ◽  
Scattering Data ◽  
Stratified Medium ◽  
X Ray ◽  
X Ray Scattering ◽  
Structure Factors ◽  
Scripting Language

A software package for performing modelling and analysis of GISAXS (grazing-incidence small-angle X-ray scattering) data within the distorted-wave Born approximation has been developed using the IGOR Pro scripting language (http://www.wavemetrics.com). The tool suite uses a slab-model approach with the Abélès matrix method to calculate X-ray reflectivity curves, electric field intensity distributions and GISAXS intensities from supported or buried scatterers arranged in two or three dimensions in a stratified medium. Models are included to calculate the scattered intensity for monodisperse, polydisperse and interacting particles with various size distributions, form factors and structure factors. The source code for the entire package is freely available, allowing anyone to develop additional tools.

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