1.

First measurement of proton's charge form factor at very low Q[sup]2 with initial state radiation

We report on a new experimental method based on initial-state radiation (ISR) in e – p scattering, which exploits the radiative tail of the elastic peak to study the properties of electromagnetic processes and to extract the proton charge form factor ( GEp ) at extremely small Q2 . The ISR technique was implemented in an experiment at the three-spectrometer facility of the Mainz Microtron (MAMI). This led to a precise validation of radiative corrections far away from elastic line and provided first measurements of GEp for 0.001≤Q2≤0.004(GeV/c)2.

COBISS.SI-ID: 30692391

2.

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

In this paper 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. In the regime where the scattering is expected to occur off a single quark, measurements show an intriguing sensitivity to gluons, the carriers of the strong interaction.

COBISS.SI-ID: 3148388

3.

Beam-recoil polarization measurement of [pi][sup]0 electroproduction on the proton in the region of the Roper resonance

The helicity-dependent recoil proton polarizations Px′ and Pz′ as well as the helicity-independent component Py have been measured in the p(e→,e′p→)π0 reaction at four-momentum transfer Q2≃0.1  GeV2, center-of-mass proton emission angle θp*≃90°, and invariant mass W≃1440  MeV. This first precise measurement of double-polarization observables in the energy domain of the Roper resonance P11(1440) by exploiting recoil polarimetry has allowed for the extraction of its scalar electroexcitation amplitude at an unprecedentedly low value of Q2, establishing a powerful instrument for probing the interplay of quark and meson degrees of freedom in the nucleon.

COBISS.SI-ID: 3114084

4.

Ground-state binding energy of [sub][Lambda] [sup]4 H from high-resolution decay-pion spectroscopy

The paper reports on a systematic study on the [Lambda] ground state binding energy of hyperhydrogen [Lambda]4H measured at the Mainz Microtron MAMI. The energy was deduced from the spectroscopy of mono-energetic pions from the two-body decays of hyperfragments, which were produced and stopped in a 9 Be target.

COBISS.SI-ID: 2984804

5.

Electroexcitation of the [Delta][sup]+(1232) at low momentum transfer

We report on new p(e,e′p)π∘ measurements at the Δ+(1232) resonance at the low momentum transfer region, where the mesonic cloud dynamics is predicted to be dominant and rapidly changing, offering a test bed for chiral effective field theory calculations.

COBISS.SI-ID: 2984548