Comparing proton momentum distributions in A = 2 and 3 nuclei via 2H 3H and 3He (e,e′p) measurements

We report the first measurement of the $(e,e'p)$ reaction cross-section ratios for Helium-3 ($^3$He), Tritium ($^3$H), and Deuterium ($d$). The measurement covered a missing momentum range of $40 \le p_{miss} \le 550$ MeV$/c$, at large momentum transfer ($\langle Q^2 \rangle \approx 1.9$ (GeV$/c$)$^2$) and $x_B>1$, which minimized contributions from non quasi-elastic (QE) reaction mechanisms. The data is compared with plane-wave impulse approximation (PWIA) calculations using realistic spectral functions and momentum distributions. The measured and PWIA-calculated cross-section ratios for $^3$He$/d$ and $^3$H$/d$ extend to just above the typical nucleon Fermi-momentum ($k_F \approx 250$ …

Polarization observables in deuteron photodisintegration below 360 MeV

High precision measurements of induced and transferred recoil proton polarization in d(polarized gamma, polarized p})n have been performed for photon energies of 277--357 MeV and theta_cm = 20 degrees -- 120 degrees. The measurements were motivated by a longstanding discrepancy between meson-baryon model calculations and data at higher energies. At the low energies of this experiment, theory continues to fail to reproduce the data, indicating that either something is missing in the calculations and/or there is a problem with the accuracy of the nucleon-nucleon potential being used.

Real and Virtual Compton Scattering (experiments)

This paper deals with Real and Virtual Compton Scattering off the proton at threshold and the way to deduce information about the nucleon polarizabilities.

The first Virtual Compton Scattering experiment at MAMI

Abstract Virtual Compton scattering, i.e. the exclusive reaction γ ∗ p → γ′p′ with γ ∗ denoting a virtual photon, provides new insights on the internal structure of the proton. Below π 0 production threshold, this experiment measures the generalized polarizabilities of the proton as defined by Guichon et al [1], [2] and Drechsel et al [3]. These new electromagnetic observables, functions of Q 2 , enlarge the concept of electric (α0 and magnetic (β) polarizabilities in Real Compton Scattering ( Q 2 =0) [4]. The first VCS experiment [5] of this kind was measured at the three spectrometer facility at the Mainz Microtron MAMI for Q 2 =0.33 GeV 2 and we present in this paper the preliminary resu…

Monte Carlo simulation of virtual Compton scattering below pion threshold

This paper describes the Monte Carlo simulation developed specifically for the VCS experiments below pion threshold that have been performed at MAMI and JLab. This simulation generates events according to the (Bethe-Heitler + Born) cross section behaviour and takes into account all relevant resolution-deteriorating effects. It determines the `effective' solid angle for the various experimental settings which are used for the precise determination of photon electroproduction absolute cross section.

Bird communities as indicators of stream quality

Riparian communities of birds are characterized by a large number of species. Among these, some species depend closely on the running water, whereas other species depend on connected wet habitats or linear forests. For fifteen years, we have censused breeding birds on a 2500 km length of river course. The results underlined the importance of (i) the upstream-downstream gradient and (ii) the effects of the landscape characteristics of the valley on the structure of bird communities. In addition, our results showed that landscape structure may be described with a limited number of variables measured from field work or from analyses of satellite data. The bird census method used (IPA, spot abu…

Effets bénéfiques d’une prise en charge pluridisciplinaire sur l’inflammation systémique : impact de l’endurance cardiorespiratoire chez des adolescents obèses présentant des troubles du sommeil

Discipline Clinique. Introduction et but de l’etude Une prise en charge (PEC) associant modification des habitudes alimentaires et reentrainement a l’exercice est efficace pour traiter le syndrome d’apnees obstructives du sommeil (SAOS) du jeune obese, mais ses effets sur l’inflammation ne sont pas totalement elucides. Les objectifs de cette etude ont ete d’evaluer, chez des adolescents obeses severes, la relation entre l’inflammation et le SAOS et de determiner les facteurs expliquant une baisse de l’inflammation a l’issue d’une PEC pluridisciplinaire de 9 mois. Materiel et methodes Les 23 participants (14,6 ± 1,2 ans) presentaient un indice de masse corporelle (IMC) de 40,2 ± 6,5 kg/m2. L…

Rosenbluth Separation of the π^{0} Electroproduction Cross Section.

We present deeply virtual $\pi^0$ electroproduction cross-section measurements at $x_B$=0.36 and three different $Q^2$--values ranging from 1.5 to 2 GeV$^2$, obtained from experiment E07-007 that ran in the Hall A at Jefferson Lab. The Rosenbluth technique was used to separate the longitudinal and transverse responses. Results demonstrate that the cross section is dominated by its transverse component, and thus is far from the asymptotic limit predicted by perturbative Quantum Chromodynamics. An indication of a non-zero longitudinal contribution is provided by the interference term $\sigma_{LT}$ also measured. Results are compared with several models based on the leading twist approach of G…

A glimpse of gluons through deeply virtual compton scattering on the proton

The internal structure of nucleons (protons and neutrons) remains one of the greatest outstanding problems in modern nuclear physics. By scattering high-energy electrons off a proton we are able to resolve its fundamental constituents and probe their momenta and positions. Here we investigate the dynamics of quarks and gluons inside nucleons using deeply virtual Compton scattering (DVCS)—a highly virtual photon scatters off the proton, which subsequently radiates a photon. DVCS interferes with the Bethe-Heitler (BH) process, where the photon is emitted by the electron rather than the proton. We report herein the full determination of the BH-DVCS interference by exploiting the distinct energ…

Experiments with the High Resolution Kaon Spectrometer at JLab Hall C and the new spectroscopy ofΛ12Bhypernuclei

Since the pioneering experiment E89-009 studying hypernuclear spectroscopy using the (e, e’K+) reaction was completed, two additional experiments, E01-011 and E05-115, were performed at Jefferson Lab. These later experiments used a modified experimental design, the "tilt method", to dramatically suppress the large electromagnetic background, and allowed for a substantial increase in luminosity. Additionally, a new kaon spectrometer, HKS (E01-011), a new electron spectrometer, HES, and a new splitting magnet (E05-115) were added to produce new data sets of precision, high-resolution hypernuclear spectroscopy. All three experiments obtained a spectrum for 12B-Lambda, which is the most charact…

New Measurements of the Transverse Beam Asymmetry for Elastic Electron Scattering from Selected Nuclei

We have measured the beam-normal single-spin asymmetry $A_n$ in the elastic scattering of 1-3 GeV transversely polarized electrons from $^1$H and for the first time from $^4$He, $^{12}$C, and $^{208}$Pb. For $^1$H, $^4$He and $^{12}$C, the measurements are in agreement with calculations that relate $A_n$ to the imaginary part of the two-photon exchange amplitude including inelastic intermediate states. Surprisingly, the $^{208}$Pb result is significantly smaller than the corresponding prediction using the same formalism. These results suggest that a systematic set of new $A_n$ measurements might emerge as a new and sensitive probe of the structure of heavy nuclei.

Transverse Beam Spin Asymmetries at Backward Angles in Elastic Electron-Proton and Quasielastic Electron-Deuteron Scattering

We have measured the beam-normal single-spin asymmetries in elastic scattering of transversely polarized electrons from the proton, and performed the first measurement in quasi-elastic scattering on the deuteron, at backward angles (lab scattering angle of 108 degrees) for Q2 = 0.22 GeV^2/c^2 and 0.63 GeV^2/c^2 at beam energies of 362 MeV and 687 MeV, respectively. The asymmetry arises due to the imaginary part of the interference of the two-photon exchange amplitude with that of single photon exchange. Results for the proton are consistent with a model calculation which includes inelastic intermediate hadronic (piN) states. An estimate of the beam-normal single-spin asymmetry for the scatt…

Virtual Compton Scattering at MAMI γ*p→ γ1p1

The virtual Compton scattering (VCS) is the electron scattering on a proton which radiates a real photon before being detected. The new observables, called Generalized Polarizabilities (GP), extracted from this VCS at threshold can be understood as the deformation of the charge and current distributions of the proton [1]. These GP are functions of the mass of the virtual photon Q2. In real Compton scattering (Q2 = 0), some polarizabilities of the nucleon are already measured [2]. With the VCS, we will generalize these observables by measuring them at different values of Q2.

Le sommeil de l’adolescent obèse est-il différent de celui de l’adolescent sportif normo-pondéré ?

Introduction L’obesite est associee a une alteration de la quantite et de la qualite du sommeil, en raison notamment d’un syndrome d’apnees obstructives du sommeil (SAOS) tandis que l’exercice physique (EP) ameliore ces parametres. Chez l’adolescent, une relation inverse entre sommeil paradoxal (SP) et exces de poids est aussi rapportee [1] . Les objectifs de cette etude sont de comparer le sommeil de l’adolescent obese (OB, IMC > 30 kg.m−2) a celui de l’adolescent sportif (SPO, EP ≥ 6 h/semaine) par polysomnographie, et d’evaluer l’impact du SAOS sur l’architecture du sommeil de l’OB. Materiel et methodes Trente-deux adolescents (22 OB : 14,9 ans, IMC = 40,2 kg.m−2 ; 12 SP : 15,7 ans, IMC …

Rosenbluth separation of the $\pi^0$ Electroproduction Cross Section off the Neutron

We report the first longitudinal/transverse separation of the deeply virtual exclusive $\pi^0$ electroproduction cross section off the neutron and coherent deuteron. The corresponding four structure functions $d\sigma_L/dt$, $d\sigma_T/dt$, $d\sigma_{LT}/dt$ and $d\sigma_{TT}/dt$ are extracted as a function of the momentum transfer to the recoil system at $Q^2$=1.75 GeV$^2$ and $x_B$=0.36. The $ed \to ed\pi^0$ cross sections are found compatible with the small values expected from theoretical models. The $en \to en\pi^0$ cross sections show a dominance from the response to transversely polarized photons, and are in good agreement with calculations based on the transversity GPDs of the nucle…

Effets d’une prise en charge pluridisciplinaire sur l’inflammation systémique chez des adolescents obèses présentant des troubles du sommeil

Objectif Evaluer chez des adolescents obeses la relation entre inflammation et SAOS et de determiner les facteurs expliquant une baisse de l’inflammation a l’issue d’une prise en charge (PEC) pluridisciplinaire de 9 mois. Methodes Vingt-trois sujets (14,6 ± 1,2 ans, IMC = 40,2 ± 6,5 kg/m2) ont participe. Le sommeil par polysomnographie, les parametres anthropometriques, la C-reactive proteine (CRP) et l’endurance cardiorespiratoire ont ete mesures en pre et post PEC. La VO2pic a ete rapportee au poids (VO2picPC ; mL/min/kg) et a la masse maigre (VO2picMM ; mL/min/kgMM). Les relations entre CRP et IMC, sexe, index de desaturation en oxygene (IDO), index de μ-eveils (IE), temps de sommeil tot…

Deeply virtual compton scattering off the neutron.

The present experiment exploits the interference between the Deeply Virtual Compton Scattering (DVCS) and the Bethe-Heitler processes to extract the imaginary part of DVCS amplitudes on the neutron and on the deuteron from the helicity-dependent D$({\vec e},e'\gamma)X$ cross section measured at $Q^2$=1.9 GeV$^2$ and $x_B$=0.36. We extract a linear combination of generalized parton distributions (GPDs) particularly sensitive to $E_q$, the least constrained GPD. A model dependent constraint on the contribution of the up and down quarks to the nucleon spin is deduced.

The first dedicated Virtual Compton Scattering experiment at MAMI

We measured the absolute cross sections for photon electro-production off the proton, ep to ep gamma , with the high resolution spectrometers at MAMI at momentum transfer q=600 MeV/c and photon polarization epsilon =0.62. We covered the momentum range for the outgoing real photon q'=33/111 MeV/c. From the extracted virtual Compton scattering amplitude we deduce values for two structure functions related to the generalized polarizabilities of the proton.

Working group on hadron polarizabilities and form factors

Virtual compton scattering under π0 threshold at Q2=0.33 GeV2. Preliminary results

We have measured the absolute unpolarized cross sections for photon electro-production off the proton ep → epγ with the Three-Spectrometer-Setup at MAMI at a momentum transfer q=600 MeV/c and a virtual photon polarization ɛ=0.62. The momentum q ′ of the outgoing real photon range from 33 to 111 MeV/c. We extracted two combinations of the recently introduced generalized polarizabilities [1,2].

Privation de sommeil, syndrome dʼapnées obstructives du sommeil et obésité de lʼadolescent : place des APA dans la prévention et le traitement de ces troubles

De par la modification du mode de vie, le rythme veille-sommeil est négligé, et le manque de sommeil est devenu aujourdʼhui une préoccupation majeure de santé publique. Chez les jeunes, lʼutilisation inadaptée des écrans le soir et la nuit chez les jeunes est à lʼorigine dʼun retard de phase et dʼune restriction de sommeil. Bien que la relation réciproque entre obésité et privation de sommeil soit déjà reconnue, il est important de comprendre les mécanismes (comportementaux, endocriniens…) conduisant lʼadolescent à une augmentation de la masse corporelle. Par ailleurs, lʼobésité est associée à une modification de lʼarchitecture du sommeil et au développement du syndrome dʼapnées obstructive…

"Table 28" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 36" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 17" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 40" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 39" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 9" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 22" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 31" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 34" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 1" of "Virtual Compton scattering under pi0 threshold at Q**2 = 0.33-GeV**2: Preliminary results."

No description provided.

"Table 33" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 6" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 11" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 37" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 29" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 1" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 21" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 25" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 2" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 32" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 5" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 16" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 24" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 23" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 14" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 26" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 20" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 8" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 10" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 13" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 27" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 38" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 35" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 15" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 30" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 19" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 12" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 4" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 3" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 18" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity dependent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.

"Table 7" of "A glimpse of gluons through deeply virtual compton scattering on the proton"

Beam helicity independent cross sections. The first systematic uncertainty is the combined correlated systematic uncertainty, the second is the point-to-point systematic uncertainty to add quadratically to the statistical uncertainty.