Form Factor Ratio Research Articles

Measurements of the Electric and Magnetic Form Factors of the Neutron for Timelike Momentum Transfer.

We present the first measurements of the electric and magnetic form factors of the neutron in the timelike (positive q^{2}) region as function of four-momentum transfer. We explored the differential cross sections of the reaction e^{+}e^{-}→n[over ¯]n with data collected with the BESIII detector at the BEPCII accelerator, corresponding to an integrated luminosity of 354.6 pb^{-1} in total at twelve center-of-mass energies between sqrt[s]=2.0-2.95 GeV. A relative uncertainty of 18% and 12% for the electric and magnetic form factors, respectively, is achieved at sqrt[s]=2.3935 GeV. Our results are comparable in accuracy to those from electron scattering in the comparable spacelike region of four-momentum transfer. The electromagnetic form factor ratio R_{em}≡|G_{E}|/|G_{M}| is within the uncertainties close to unity. We compare our result on |G_{E}| and |G_{M}| to recent model predictions, and the measurements in the spacelike region to test the analyticity of electromagnetic form factors.

Morphological characteristics of Kanthatmakur vagu Watershed of Warangal District: Using Geographical Information System (GIS)

The present study relates to the morphometric analysis of Kanthatmakur vagu watershed using GIS. The GIS platform facilitates the analysis of various morphometric parameters. This watershed has higher order of 5th order. The present study has area of about 440.4 Km2 with total length of basin is 45.5 Km. Total number of streams in the basin is 635, ranging from 10 to 319. The basin area exhibits dendritic drainage pattern with bifurcation ratio ranges from 0.1 to 9.2, with mean bifurcation ration of 3.4. Length of stream of all orders are 481.8 km. Length of overland slow is 0.55 km and perimeter of the basin found to be 119.7 km. Areal aspects such as drainage density is calculated as 1.1, drainage frequency is 1.4 and drainage texture calculated as 5.3. Infiltration number of the watershed is 0.8. The watershed has 0.3 form factor ratio, 0.5 elongation ration and 0.4 circularity ratio. Relief of the watershed is 261m and ratio of relief is 6.3. The characteristics of morphological analysis of the Kanthatmakur vagu watershed has peak flow, is an elongated and less probable to flooding as well as moderate to slightly steep slope. In the watershed infiltration is high and run off will be low.

The study of morphological characteristics for best management practices over the Halayapura micro-watershed of Karnataka, India, using remote sensing and geospatial techniques

The morphometric analysis was carried out on the Halayapura micro-watershed in Karnataka, India. Using ArcGIS 10.2.2 and applying the DEM model, the micro-watershed was subjected to quantitative investigation to determine the channel network involved and understand geo-hydrological behavior. In addition, remote sensing and geospatial techniques were used to study the micro-watershed drainage analysis and its associated parameters, such as stream order, stream length, stream frequency, drainage density, texture ratio, form factor, circulatory ratio, elongation ratio, bifurcation ratio, and compactness coefficient for the micro watershed, were evaluated. According to the findings, the stream order ranges from I to IV, with 97 streams in the micro-watershed. Streams of 72, 19, 5, and 1 are found in the I, II III, and IV order, respectively. The bifurcation values range from 3.78 to 5.00, with the average weight around 3.14. The elongation ratio and farm factor are 0.77 and 0.46, respectively. The drainage density of the micro watershed is 5.20 km/km2. The form factor, circularity, and elongation ratio contribute to a basin with an elongated shape through decreased flood proneness, erosion, and sediment transport capacity. The results of the micro-watershed morphometric assessment are critical for evaluating and managing water resources and selecting a recharge structure for future water management in the study region.

Morphometric analysis of low mountains for mapping flash flood susceptibility in headwaters

Morphometric indices from high-resolution DEMs can contribute to the estimation of flash flood susceptibility in mountainous areas. We have screened 25 morphometric indices commonly used in literature, and based on a correlation matrix, selected those which showed the strongest relationship with flash flood generation: area (A), drainage texture (Rt), drainage density (Dd), elongation ratio (Re), form factor (Ff), lemniscate method (k), Gravelius coefficient (GC), forested area (Fa) and relief ratio (Rr). Among them Dd, Rt and Rr had a direct impact on flash flood generation, while A, Re, Fa, Ff, k and GC are in inverse relationship with the intensity of flash floods. Our summary map shows the prioritization of the watersheds on a scale of 0 to 9. The flash flood susceptibility ranking was empirically verified using hydrological data (20-year water regime obtained from 14 official stream gauges). Our conclusions only partially agree with former observations which may be explained by the particular lithology and morphology of the Mecsek Mountains. Since the lower sections of the watersheds are urbanized, for optimal watershed management more detailed GIS analyses of anthropogenic controls on flash flood hazard are needed in the future.

Morphometric evaluation of Ranikhola watershed in Sikkim, India using geospatial technique

Morphological parameters are linked with the hydrological behaviour of the watershed. It helps to understand different basin characteristics. Characterization of quantitative morphology and river basin analysis is the way to implement proper river basin planning and management of soil and water conservation measures. In the present study, Cartosat-1 Digital Elevation Model (DEM) was used in Geographic Information System (GIS) environment to determine the morphometric parameters (stream length, stream order, stream frequency, bifurcation ratio, form factor, drainage density, circulatory ratio, etc.) of the Ranikhola watershed of Sikkim state, India. The slope of a major portion of the watershed area was found to be less than 30% (42 km2) and has a drainage density of 0.585 km-1. The lower value of drainage density in the watershed indicates a relatively lower streams frequency over the watershed. The elongation ratio, form factor, and circulatory ratio were estimated as 0.665, 0.347, and 0.510, respectively, which indicate that the watershed is elongated in shape, having gentle slopes and long flow paths. The relief ratio for the watershed was estimated to be 0.187, which indicates the watershed has a low elevation difference, low runoff, and high groundwater potential. This kind of morphometric analysis is required for the watershed characterization and helps to understand the hydrogeological behavior of the watershed.

Morphometric Interpretation for Sub-Basin Management Planning and Practices in Hassan District, Karnataka India Using GIS and Remote Sensing

Classification and categorization of water basins is essential in sustainable growth, planning and management. Implementing the modern strategic techniques over a wider area needs huge resources and proper planning. Hence, morphometric analysis can be used as necessary tool for prioritizing sub- watersheds in the present study. The study area encompasses 265 sq. km, which is divided into nine sub-basins, specifically Bannur (W-1), Conimarur (W-2), Hampapura (W-3), Harohalli (W-4), Kaneyar (W-6), Konanuru (W-7), Saraguru (W-8), and Torenuru (W-9) ranging from 8 to 64 km2. The Survey of Indian toposheets and Digital Terrain Model are utilized to explain the drainage characteristics. The study reveals dendritic stream arrangement of fourth to fifth order. The density of drainage ranged between 1.03 to 1.32 km/km2, suggesting that the drainage texture was coarse to moderate, but low infiltration and high runoff. The change in stream length ratio over time implies that geomorphological progress is approaching its end. The bifurcation ratios range from 0.5 to 2.58, indicating that the region has good lithological control over the stream system and whole sub-watersheds are classified as "normal”. The form factor and circulatory ratio suggest elongated to circular sub-watersheds. Thus, the results of this analysis would be useful for the basin management planning and groundwater development. Keywords: Morphometry, Aerial Aspects, Linear aspects, Relief aspects, Hassan District

High resolution morphometric studies with special reference to hydrological setup of Khapri watershed, Dangs district, Gujarat, Western India

High resolution morphometric study of Khapri watershed is performed to assess spatial distribution of morphometric parameters and related hydrological significance. For the present study, topographic maps (1:50,000), SRTM DEM, isopleth maps generated in Arc GIS 10.4, pie-diagrams and correlation technique are used. The high drainage density (3.07 km/km2), high stream frequency (4.69/km2), fine drainage texture (14.39/km) and low constant of channel maintenance (0.32) indicate less transmissible nature of underlying rocks and rugged topography (R n = 2.73) with steep slopes, leading to high runoff and low infiltration. These factors indicate water stressed condition, despite heavy rainfall of 2000 mm in the watershed. Major part of the watershed has moderate to steep and longer slopes, responsible for closely spaced drainages and elongated shape. The elongated nature is supported by circulatory ratio, form factor and elongation ratio. The results are used to identify potential areas for water harvesting (WHS) and recharging structures (WRS). Key policy highlights High resolution morphometric studies facilitate spatial distribution analysis of runoff and infiltration potential. Less transmissible rocks, dominance of high drainage density, fine drainage texture, steep slope and high ruggedness of Khapri watershed lead to high runoff and low infiltration. Inspite of high rainfall of 2000 mm, the area faces scarcity of surface and ground water during non-rainy period. The research outcome is used to identify potential areas for water harvesting (WHS) and recharging structures (WRS).

Magnetic moments of the octet, decuplet, low-lying charm, and low-lying bottom baryons in a nuclear medium

Abstract We study the magnetic moments of the octet, decuplet, low-lying charm, and low-lying bottom baryons with nonzero light quarks in symmetric nuclear matter using the quark–meson coupling (QMC) model, which satisfies the constraint for the allowed maximum change (swelling) of the in-medium nucleon size derived from the y-scaling data for 3He(e, e′) and 56Fe(e, e′). This is the first study to estimate the in-medium magnetic moments of the low-lying charm and bottom baryons with nonzero light quarks. The present QMC model also satisfies the expected allowed maximum enhancement of the nucleon magnetic moments in nuclear matter. Moreover, it has been proven that the calculated in-medium to free proton electromagnetic form factor (EMFF) ratios calculated within the QMC model reproduce well the proton EMFF super ratio extracted from $^4{\rm He}(\vec{e},e^{\prime }\vec{p})^3{\rm H}$ at Jefferson Laboratory. The medium modifications of the magnetic moments are estimated by evaluating the in-medium to free space baryon magnetic moment ratios to compensate the MIT bag deficiency to describe the free space octet baryon magnetic moments, where ratios are often measured directly in experiments even without knowing the absolute values, such as the free and bound proton electromagnetic form factors, as well as the European Muon Collaboration effect to extract the structure function F2 ratio of the bound to free nucleons by the corresponding cross section ratio. We also present the results calculated with the different current quark mass values for the strange and bottom quarks to see the possible impact. Furthermore, for practical use we give the explicit density-dependent parametrizations for the vector potentials of the baryons and light-(u, d) quarks, as well as for the effective masses of the baryons treated in this study, and of the mesons ω, ρ, K, K*, η, $\eta^{\prime}$, D, D*, B, and B*.

Reliability Analysis of the Results of the Known Experiments on Measuring of the Sachs Form Factor Ratio Using the Rosenbluth Technique. Polarization of the Final Proton in the $$e\vec {p} \to e\vec {p}$$ Elastic Process

A criterion for assessing the reliability of measurements of the Sachs form factor ratio using the Rosenbluth technique is proposed and applied to an analysis of three known experiments (Andivahis1994, Walker1994, Qattan2005) and a recent experiment on the CEBAF accelerator upgraded to 12 GeV at JLab (arXiv:2103.01842 [nucl-ex]). Based on the results of the JLab polarization experiments on measuring the ratio $\mu_p G_E/G_M$ in the $\vec e p \to e \vec p$ process, in the kinematics of the SANE Collaboration experiment (2020) on the measurement of double spin asymmetry in the $\vec e \vec p \to e p$ process numerical calculations are performed for the $Q^2$ dependence of polarization transferred to the proton in the $e \vec p \to e \vec p$ process when the initial proton at rest is partially polarized along the direction of motion of the detected recoil proton.

Time-like Proton Form Factors with Initial State Radiation Technique

Electromagnetic form factors are fundamental quantities describing the internal structure of hadrons. They can be measured with scattering processes in the space-like region and annihilation processes in the time-like region. The two regions are connected by crossing symmetry. The measurements of the proton electromagnetic form factors in the time-like region using the initial state radiation technique are reviewed. Recent experimental studies have shown that initial state radiation processes at high luminosity electron-positron colliders can be effectively used to probe the electromagnetic structure of hadrons. The BABAR experiment at the B-factory PEP-II in Stanford and the BESIII experiment at BEPCII (an electron positron collider in the τ-charm mass region) in Beijing have measured the time-like form factors of the proton using the initial state radiation process e+e−→pp¯γ. The two kinematical regions where the photon is emitted from the initial state at small and large polar angles have been investigated. In the first case, the photon is in the region not covered by the detector acceptance and is not detected. The Born cross section and the proton effective form factor have been measured over a wide and continuous range of the the momentum transfer squared q2 from the threshold up to 42 (GeV/c)2. The ratio of electric and magnetic form factors of the proton has been also determined. In this report, the theoretical aspect and the experimental studies of the initial state radiation process e+e−→pp¯γ are described. The measurements of the Born cross section and the proton form factors obtained in these analyses near the threshold region and in the relatively large q2 region are examined. The experimental results are compared to the predictions from theory and models. Their impact on our understanding of the nucleon structure is discussed.

Production Mechanism of the Charmed Baryon Λc+

As the lightest charmed baryon, precision measurement of the pair production cross section of Λc+ provides unprecedented experimental information for the investigation of baryon production mechanism. In addition, the extraction of the polar angle distributions of the outgoing Λc+ in the annihilation of the electron–positron help to determine its electromagnetic form factors, which is currently the unique key to access the internal structure of the baryons. In this article, the measurement of e+e−→Λc+Λ¯c− process via the initial state radiation technique at Belle detector and direct electron–positron annihilation at BESIII with discrete center-of-mass energies near threshold are briefly reviewed. In addition, the electromagnetic form factor ratios of Λc+ measured by BESIII are also investigated. A few theoretical models that parameterize the center-of-mass energy dependence of the cross section and electromagnetic form factors of baryon are introduced and the contributions of Λc+ data to them are discussed.

Direct TPE measurement via $$e^+p/e^-p$$ scattering at low $$\varepsilon $$ in Hall A

The proton elastic form factor ratio can be measured either via Rosenbluth separation in an experiment with unpolarized beam and target, or via the use of polarization degrees of freedom. However, data produced by these two approaches show a discrepancy, increasing with $Q^2$. The proposed explanation of this discrepancy - two-photon exchange - has been tested recently by three experiments. The results support the existence of a small two-photon exchange effect but cannot establish that theoretical treatments at the measured momentum transfers are valid. At larger momentum transfers, theory remains untested, and without further data, it is impossible to resolve the discrepancy. A positron beam at Jefferson Lab allows us to directly measure two-photon exchange over an extended $Q^2$ and $\epsilon$ range with high precision. With this, we can validate whether the effect reconciles the form factor ratio measurements, and test several theoretical approaches, valid in different parts of the tested $Q^2$ range. In this proposal, we describe a measurement program in Hall A that combines the Super BigBite, BigBite, and High Resolution Spectrometers to directly measure the two-photon effect. Though the limited beam current of the positron beam will restrict the kinematic reach, this measurement will have very small systematic uncertainties, making it a clean probe of two photon exchange.

Nucleon electroweak form factors using spin-improved holographic light-front wavefunctions

We construct spin-improved holographic light front wavefunctions for the nucleons (viewed as quark-diquark systems) and use them to successfully predict their electromagnetic Sachs form factors, their electromagnetic charge radii, as well as the axial form factor, charge and radius of the proton. The confinement scale is the universal mass scale of light-front holography, previously extracted from spectroscopic data for light hadrons. With the Dirac and Pauli form factors normalized using the quark counting rules and the measured anomalous magnetic moments respectively, the masses of the quark and diquark are the only remaining adjustable parameters. We fix them using the data set for the proton's Dirac-to-Pauli form factor ratio, and then predict all other data without any further adjustments of parameters. Agreement with data at low momentum-transfer is excellent. Our findings support the idea that light (pseudoscalar and vector) mesons and the nucleons share a nonperturbative universal holographic light-front wavefunction which is modified differently by their spin structures.

The electromagnetic form factors of $$\Lambda _c$$ hyperon in the vector meson dominance model

We apply a modified vector meson dominance (VMD) model to analyze the electromagnetic form factors of the $\Lambda_c$ hyperon in the time-like reaction $e^+e^-\rightarrow \Lambda_c^+ \bar{\Lambda}_c^-$. In the model, we include the contributions from the vector charmed mesons and their excitations $\psi(1S)$, $\psi(2S)$, $\psi(3770)$, $\psi(4040)$, $\psi(4160)$ and $\psi(4415)$. We perform a combined fit to the available data on the Born cross section in reaction $e^+e^-\rightarrow \Lambda_c^+ \bar{\Lambda}_c^-$ and the ratio of the electromagnetic form factors $|G_E/G_M|$ to obtain the values of the model parameters. Our results show that the VMD model can simultaneously describe the data of electromagnetic form factors from the Belle and BESIII Collaborations, and the behavior of $|G_E/G_M|$ for the BESIII data can be qualitatively reproduced by the VMD model prediction at the threshold region. Moreover, we predict the single and double polarization observables in $e^+e^-\rightarrow \Lambda_c^+ \bar{\Lambda}_c^-$ reactions, which are experimentally accessible in the polarized process. We also obtain the form factors of the $\Lambda_c$ hyperon in the space-like region via analytic continuing the time-like form factors.

Use of Geospatial Tools in Morphometric Analysis and Prioritisation of Sub-catchments of the Soungrougrou (Casamance Basin)

Abstract The prioritisation of catchments, particularly in the context of catchment plans and management programmes, is part of water resources development. In fact, morphometric analysis assisted by geospatial technology is carried out by prioritising sub-catchments according to their natural resource availability characteristics. Information on the geomorphology and erosion factors of the study area is used in the area in the preparation of local models of ungauged sub-catchments, which otherwise lack an adequate hydrological database. The objective of this paper is to use geographic information systems (GISs) in morphometric analysis to prioritise sub-catchments of the Soungrougrou (a tributary of the Casamance River). In this respect, the integrated methodology involving morphometric aspects from geospatial technology is used. To carry out the geospatial research, basic mathematical equations used in a GIS environment were used to measure a series of aspects of hydrology such as flow length, flow length ratio, bifurcation ratio, drainage density, drainage texture, flow frequency, elongation rate, circularity ratio, form factor, relief and relief ratio. The results divided the whole catchment into three priority areas, namely high, medium and low. The results are relevant for establishing soil and water conservation plans in the Soungrougrou basin, as well as adequate groundwater production and management. The high category (sub-basins 6, 8, 14, 17 and 18) is subject to maximum soil erosion, which requires immediate intervention to avoid possible natural hazards.

Localization in the kicked Ising chain

Determining the border between ergodic and localized behavior is of central interest for interacting many-body systems. We consider here the recently quite popular kicked Ising chain. A convenient description of such a many-body system is achieved by the dual operator that evolves the system in contrast to the time-evolution operator not in time but particle direction. We focus in this paper on the largest eigenvalue of a function of the dual operator. It is identified to be a convenient tool to determine if the system shows ergodic or many-body localized features. We analytically explain the eigenvalue structure by perturbation theory in the vicinity of the noninteracting system. This result agrees with the numerics for small times in a previous work [Braun et al., Phys. Rev. E 101, 052201 (2020)]. Given that a direct numerical computation of this largest eigenvalue is only possible for small times, another achievement of this paper is to provide a way to determine this eigenvalue by the ratio of spectral form factors for adjacent particle numbers. By extensive large-time numerical computations of the spectral form factor, we can then distinguish between localized and ergodic system features and compute the Thouless time, i.e., the transition time between these regimes in the thermodynamic limit.

Morphometric analysis of a drainage basin using geographical information system in Gilgel Abay watershed, Lake Tana Basin, upper Blue Nile Basin, Ethiopia

GIS and remote sensing approach is an effective tool to determine the morphological characteristics of the basin. Gilgel Abay watershed is stretched between latitude 10.56° to 11.22° N and longitude 36.44° to 37.03° E which is one major contributing river of Lake Tana which is the source of Blue Nile. The present study addressed linear and areal morphometric aspect of the watershed. The study deals with emphasis on the evolution of morphometric parameters such as stream order, stream length, bifurcation ratio, drainage density, stream frequency, texture ratio, elongation ratio, circularity ratio, and form factor ratio. The morphometric analysis of the basin revealed that Gilgel Abay is firth-order drainage basin with total of 662 drainage network, of which 511 are first order, 111 are second order, 30 are third order, 9 are fourth order, and 1 is fifth-order stream. The total length of stream is longer for first order and decrease with increasing stream order. The mean bifurcation ratio is 5.16 which is greater than the standard range, and it indicates that basin is mountainous and susceptible to flooding. Low drainage density is observed which is 0.6 km−2. It indicates that basin is highly permeable and thick vegetation cover. Areal aspect of the morphometric analysis of the basin revealed that the basin is slightly potential to flooding and soil erosion, indicating that runoff generated from the upland area of the watershed is significantly infiltrated at the gentle downstream part and contributing to groundwater potential. Further studies with the help of GIS and remote sensing with high-resolution remote sensing data integrating with ground control data in the field are more effective to formulate appropriate type of natural resource management system.

Target-normal single spin asymmetries measured with positrons

Two-photon exchange and the larger class of hadronic box diagrams are difficult to calculate without a large degree of model-dependence. At the same time, these processes are significant radiative corrections in parity-violating electron scattering, in neutron decay, and may even be responsible for the proton’s form factor ratio discrepancy. New kinds of experimental data are needed to help constrain models and guide future box-diagram calculations. The target-normal single spin asymmetry, $$A_n$$ , formed with an unpolarized beam scattering from a target that is polarized normal to the scattering plane, is sensitive to the imaginary part of the two-photon exchange amplitude, and can provide a valuable constraint. A measurement with both electrons and positrons can reduce sources of experimental error, and distinguish between the effects of two-photon exchange and those of time-reversal symmetry violation. This article describes a proposed experiment in Hall A, using the new Super Big-Bite Spectrometer that can cover a momentum transfer range in the critical zone of uncertainty between where hadronic calculations and those based on partonic degrees of freedom are expected to be accurate.

Polarization transfer in $$\varvec{e}^+p \rightarrow e^+ \varvec{p}$$ scattering using the Super BigBite Spectrometer

The effects of multi-photon-exchange and other higher-order QED corrections on elastic electron-proton scattering have been a subject of high experimental and theoretical interest since the polarization transfer measurements of the proton electromagnetic form factor ratio \(G_E^p/G_M^p\) at large momentum transfer \(Q^2\) conclusively established the strong decrease of this ratio with \(Q^2\) for \(Q^2 \gtrsim 1\) \(\hbox {GeV}^2\). This result is incompatible with previous extractions of this quantity from cross section measurements using the Rosenbluth Separation technique. Much experimental attention has been focused on extracting the two-photon exchange (TPE) effect through the unpolarized \(e^+p/e^-p\) cross section ratio, but polarization transfer in polarized elastic scattering can also reveal evidence of hard two-photon exchange. Furthermore, it has a different sensitivity to the generalized TPE form factors, meaning that measurements provide new information that cannot be gleaned from unpolarized scattering alone. Both \(\epsilon \)-dependence of polarization transfer at fixed \(Q^2\), and deviations between electron-proton and positron-proton scattering are key signatures of hard TPE. A polarized positron beam at Jefferson Lab would present a unique opportunity to make the first measurement of positron polarization transfer, and comparison with electron-scattering data would place valuable constraints on hard TPE. Here, we propose a measurement program in Hall A that combines the Super BigBite Spectrometer for measuring recoil proton polarization, with a non-magnetic calorimetric detector for triggering on elastically scattered positrons. Though the reduced beam current of the positron beam will restrict the kinematic reach, this measurement will have very small systematic uncertainties, making it a clean probe of TPE.

Measurement of proton electromagnetic form factors in the time-like region using initial state radiation at BESIII

The electromagnetic process e+e−→pp¯ is studied with the initial-state-radiation technique using 7.5 fb−1 of data collected by the BESIII experiment at seven energy points from 3.773 to 4.600 GeV. The Born cross section and the effective form factor of the proton are measured from the production threshold to 3.0 GeV/c2 using the pp¯ invariant-mass spectrum. The ratio of electric and magnetic form factors of the proton is determined from the analysis of the proton-helicity angular distribution.