The GPD experimental program at Jefferson Lab

International audienceRecent results on the Generalized Parton Distribution (GPD) program at Jefferson Lab (JLab) will be presented. The emphasis will be in the Hall A program aiming at measuring Q2−dependences of different terms of the Deeply Virtual Compton Scattering (DVCS) cross section. This is a fundamental step before one can extract GPD information from JLab DVCS data. The upcoming program in Hall A, using both a 6 GeV beam (≈ 2010) and a 11 GeV beam (≈ 2015) will also be described

The Generalized Parton Distributions program in Hall A at Jefferson Lab

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Deep exclusive reactions at Jefferson Lab Hall A

International audienceRecent results on the Generalized Parton Distribution (GPD) programat Jefferson Lab (JLab) will be presented. The emphasis will be in the Hall A program aiming at measuring Q2−dependences of different terms of the Deeply Virtual Compton Scattering (DVCS) cross section. This is a fundamental step before one can extract GPD information from JLab DVCS data. The upcoming program in Hall A, using both a 6 GeV beam (2010) and a 11 GeV beam (≈ 2015) will also be described

Exclusive neutral pion electroproduction in the deeply virtual regime

We present measurements of the ep -\u3e ep pi(0) cross section extracted at two values of four-momentum transfer Q(2) = 1.9 GeV(2) and Q(2) = 2.3 GeV(2) at Jefferson Lab Hall A. The kinematic range allows one to study the evolution of the extracted cross section as a function of Q(2) and W. Results are confronted with Regge-inspired calculations and GPD predictions. An intepretation of our data within the framework of semi-inclusive deep inelastic scattering is also discussed

Probing the nucleon structure with CLAS

An overview of recent results with CLAS is presented with emphasis on nucleon resonance studies, nucleon spin structure, and generalized parton distributions.Comment: Plenary talk presented at NSTAR 2007, Bonn, German

The Jlab Upgrade - Studies of the Nucleon with CLAS12

An overview is presented on the program to study the nucleon structure at the 12 GeV JLab upgrade using the CLAS12 detector. The focus is on deeply virtual exclusive processes to access the generalized parton distributions, semni-inclusive processes to study transverse momentum dependent distribution functions, and inclusive spin structure functions and resonance transition form factors at high Q^2 and with high precision.Comment: 7 pages, 12 figures, NSTAR 2007 conference, Bonn, September 5-8, 200

Gut-derived short-chain fatty acids modulate skin barrier integrity by promoting keratinocyte metabolism and differentiation

Barrier integrity is central to the maintenance of healthy immunological homeostasis. Impaired skin barrier function is linked with enhanced allergen sensitization and the development of diseases such as atopic dermatitis (AD), which can precede the development of other allergic disorders, for example, food allergies and asthma. Epidemiological evidence indicates that children suffering from allergies have lower levels of dietary fibre-derived short-chain fatty acids (SCFA). Using an experimental model of AD-like skin inflammation, we report that a fermentable fibre-rich diet alleviates systemic allergen sensitization and disease severity. The gut-skin axis underpins this phenomenon through SCFA production, particularly butyrate, which strengthens skin barrier function by altering mitochondrial metabolism of epidermal keratinocytes and the production of key structural components. Our results demonstrate that dietary fibre and SCFA improve epidermal barrier integrity, ultimately limiting early allergen sensitization and disease development. The Graphical Abstract was designed using Servier Medical Art images (https://smart.servier.com). [Image: see text

Moments of the neutron g2g_2 structure function at intermediate Q2Q^2

We present new experimental results of the $^3$He spin structure function $g_2$ in the resonance region at $Q^2$ values between 1.2 and 3.0 (GeV/c)$^2$. Spin dependent moments of the neutron were then extracted. Our main result, the resonance contribution to the neutron $d_2$ matrix element, was found to be small at $$=2.4 (GeV/c)$^2$ and in agreement with the Lattice QCD calculation. The Burkhardt-Cottingham sum rule for $^3$He and the neutron was tested with the measured data and using the Wandzura-Wilczek relation for the low $x$ unmeasured region. A small deviation was observed at $Q^2$ values between 0.5 and 1.2 (GeV/c)$^2$ for the neutron

Quark-Hadron Duality in Neutron (3He) Spin Structure

We present experimental results of the first high-precision test of quark-hadron duality in the spin-structure function g_1 of the neutron and $^3$He using a polarized 3He target in the four-momentum-transfer-squared range from 0.7 to 4.0 (GeV/c)^2. Global duality is observed for the spin-structure function g_1 down to at least Q^2 = 1.8 (GeV/c)^2 in both targets. We have also formed the photon-nucleon asymmetry A_1 in the resonance region for 3He and found no strong Q^2-dependence above 2.2 (GeV/c)^2.Comment: 13 pages, 3 figure