Measurements of ep→e′π+π−p′ cross sections with CLAS at 1.40

Abstract

This paper reports new exclusive cross sections for ep → e π + π − p using the CLAS detector at Jefferson Laboratory. These results are presented for the first time at photon virtualities 2.0 GeV 2 < Q 2 < 5.0 GeV 2 in the center-of-mass energy range 1.4 GeV < W < 2.0 GeV, which covers a large part of the nucleon resonance region. Using a model developed for the phenomenological analysis of electroproduction data, we see strong indications that the relative contributions from the resonant cross sections at W < 1.74 GeV increase with Q 2 . These data considerably extend the kinematic reach of previous measurements. Exclusive ep → e π + π − p cross section measurements are of particular importance for the extraction of resonance electrocouplings in the mass range above 1.6 GeV.

Structure of the Nucleon and Its First Radial Excitation

“…and γ * n → R 0 (dashed green curves). In all cases, the results on x ∈ [6,12] are projections, obtained via extrapolation of analytic approximations to our results on x ∈ [0, 6] (see Ref. [59] for details).…”

“…Moreover, QCD-based approaches that compute form factors at large photon virtualities are needed because the so-called meson-cloud often screens the dressed-quark core of all baryons at low momenta [8,9]. On the experimental side, a substantial progress has been made in the extraction of transition electrocouplings, g vN N * , from meson electroproduction data, obtained primarily with the CLAS detector at the Jefferson Laboratory (JLab) [3,[10][11][12][13][14][15]. This manuscript is arranged as follows.…”

Nucleon resonance contributions to unpolarized inclusive electron scattering

“…Furthermore, the data for ∆(1620)1/2 − , N (1720) 3/2 + , N (1720) 3/2 + and ∆(1700) 3/2 − cover a smaller range of Q 2 < 1.5 GeV 2 when compared to the other resonances, Q 2 < 5 GeV 2 . For these resonances, we have preliminary estimates of the central electrocoupling values [43] based on the good description of the π + π − p electroproduction data off protons from CLAS at 2.0 GeV 2 < Q 2 < 5.0 GeV 2 [58][59][60]. We give a conservative extrapolation uncertainty estimate for these resonance electrocouplings of at least 20% (when the relative error as calculated above is smaller).…”

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

“…To this end, a systematic analysis of the data collected on various nuclear targets by different experiments using the CLAS detector in Hall B at Jefferson Laboratory, while not completely addressing the requirements outlined above, would be an important advance. So far, the published studies focused on specific hadronic processes with hydrogen targets [42][43][44][45][46][47][48][49]. These should already be useful for testing generator models for certain hadronic processes, such as ρ meson production through higher resonances.…”