Exclusive π0p electroproduction off protons in the resonance region at photon virtualities 0.4GeV2≤Q2

Abstract

The exclusive electroproduction process ep → e p π 0 was measured in the range of photon virtualities Q 2 = 0.4−1.0 GeV 2 and the invariant mass range of the pπ 0 system of W = 1.1−1.8 GeV. These kinematics are covered in exclusive π 0 electroproduction off the proton with nearly complete angular coverage in the pπ 0 center-of-mass system and with high statistical accuracy. Nearly 36000 cross section points were measured, and the structure functions σT + σL, σLT , and σT T , were extracted via fitting the φ π 0 dependence of the cross section. A Legendre polynomial expansion analysis demonstrates the sensitivity of our data to high-lying N * and ∆ * resonances with M > 1.6 GeV. As part of a broad effort to determine the electrocouplings of the N * and ∆ * resonances using both single-and double-pion electroproduction, this dataset is crucial for the reliable extraction of the high-lying resonance electrocouplings from the combined isospin analysis of the N π and π + π − p channels.PACS numbers:

Towards a combined analysis of inclusive/exclusive electroproduction

“…Future experimental results from CLAS on resonance electrocouplings in the mass range from 1.6 GeV to 2.0 GeV and 0.4 GeV 2 < Q 2 < 5.0 GeV 2 expected from the data [23][24][25][26] will improve our estimates on the contributions from excited nucleon states in the mass range above 1.6 GeV. Furthermore, they will provide the first results on electrocouplings of the resonances in the mass range above 1.9 GeV, where the transition from the resonance to deep inelastic scattering regions takes place.…”

Lepton-nucleus cross section measurements for DUNE with the LDMX detector

“…Efficiency uncertainties should be smaller and more uniform than the ∼4% level achieved by the less hermetic CLAS detector (see, e.g., Ref. [49]). Momentum resolution uncertainties should be comparable to the ∼3% achieved at HPS [80], which has a similar detector geometry and beam.…”

Validation of Neutrino Energy Estimation Using Electron Validation of Neutrino Energy Estimation Using Electron Scattering Data Scattering

“…In the single photon exchange approximation the virtual photon cross section dσ dΩ * π for exclusive π 0 p electroproduction can be written in terms of experimental exclusive structure functions σ T + σ L ,σ LT and σ TT as shown in Eq. 77 [67]. Each of these functions depends implicitly on (W, Q 2 , θ π ) and is described by different products of reaction amplitudes and their complex conjugate…”

“…183 and is the azimuthal angle between the hadronic and leptonic planes and θ π is the angle between the direction of the pion and the virtual photon. These expressions are taken from π 0 p electroproduction studies in [67], but they can also be used for charged pion production studies, like in our case.…”

“…For this study we have used the values of exclusive structure functions σ T + σ L , σ TT and σ LT from [67] shown for cos θ π = 0.1 and 0.4 ≤ Q 2 ≤ 1 GeV 2 . We have used the largest In the A(e, e ) inclusive analysis, we looked at the events with one detected charged pion and rotated the pion many times around q to find the weight for undetected pion events, which is given by the following expression;…”