| 1. |
- Burdeinyi, D., et al.
(författare)
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Cross section asymmetry of two-body carbon disintegration 12C(γ,p)11B with polarized photons at energy 40–50 MeV
- 2017
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Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474. ; 957, s. 321-331
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Tidskriftsartikel (refereegranskat)abstract
- The cross section asymmetry of C12(γ,p01)B11 and C12(γ,p2−6)B11 reactions has been studied at the energy range 40–55 MeV, using linearly polarized tagged photons of the MAX-lab facility. The asymmetry of the C12(γ,p01)B11 processes, which assume the one-body mechanism of the reaction, is Σ≈0.82±0.05 for photon energies 45–50 MeV. The asymmetry for the C12(γ,p2−6)B11 reactions, which produce a maximum at excitation energy ∼6 MeV, is Σ≈0.53±0.13 for a photon energy 49 MeV. It is close to the asymmetry of reaction of the free deuteron photodisintegration, and can be resulted from the two-body mechanism of the photon absorption.
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| 2. |
- Myers, L. S., et al.
(författare)
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Compton scattering from the deuteron below pion-production threshold
- 2015
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 92:2
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Tidskriftsartikel (refereegranskat)abstract
- Differential cross sections for elastic scattering of photons from the deuteron have recently been measured at the Tagged-Photon Facility at the MAX IV Laboratory in Lund, Sweden. These first new measurements in more than a decade further constrain the isoscalar electromagnetic polarizabilities of the nucleon and provide the first-ever results above 100 MeV, where the sensitivity to the polarizabilities is increased. We add 23 points between 70 and 112 MeV, at angles 60 degrees, 120 degrees, and 150 degrees. Analysis of these data using a chiral effective field theory indicates that the cross sections are both self-consistent and consistent with previous measurements. Extracted values of alpha(s) = [12.1 +/- 0.8(stat) +/- 0.2(BSR) +/- 0.8(th)] x 10(-4) fm(3) and beta(s) = [2.4 +/- 0.8(stat) +/- 0.2(BSR) +/- 0.8(th)] x 10(-4) fm(3) are obtained from a fit to these 23 new data points. This paper presents in detail the experimental conditions and the data analysis used to extract the cross sections.
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| 3. |
- Singh, B. P., et al.
(författare)
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Experimental access to Transition Distribution Amplitudes with the PANDA experiment at FAIR
- 2015
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Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 51:8
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Tidskriftsartikel (refereegranskat)abstract
- Baryon-to-meson Transition Distribution Amplitudes (TDAs) encoding valuable new information on hadron structure appear as building blocks in the collinear factorized description for several types of hard exclusive reactions. In this paper, we address the possibility of accessing nucleon-to-pion (pi N) TDAs from (p) over barp -> e(+)e(-)pi(0) reaction with the future PANDA detector at the FAIR facility. At high center-of-mass energy and high invariant mass squared of the lepton pair q(2), the amplitude of the signal channel (p) over barp -> e(+)e(-)pi(0) admits a QCD factorized description in terms of pi N TDAs and nucleon Distribution Amplitudes (DAs) in the forward aid backward kinematic regimes. Assuming the validity of this factorized description, we perform feasibility studies for measuring (p) over barp -> e(+)e(-)pi(0) with the PANDA detector. Detailed simulations on signal reconstruction efficiency as well as on rejection of the most severe background channel, i.e. (p) over barp -> pi(+)pi(-)pi(0) were performed for the center-of-mass energy squared s = 5 GeV2 and s = 10 GeV2, in the kinematic regions 3.0 < q(2) < 4.3 GeV2 and 5 < q(2) < 9 GeV2, respectively, with a neutral pion scattered in the forward or backward cone vertical bar cos theta(pi 0)vertical bar > 0.5 in the proton-antiproton center-of-mass frame. Results of the simulation show that the particle identification capabilities of the PANDA detector will allow to achieve a background rejection factor of 5 . 10(7) (1 . 10(7)) at low (high) q(2) for s = 5 GeV2, and of 1 . 10(8) (6 . 10(6)) at low (high) q(2) for s = 10 GeV2, while keeping the signal reconstruction efficiency at around 40%. At both energies, a clean lepton signal can be reconstructed with the expected statistics corresponding to 2 of integrated luminosity. The cross sections obtained from the simulations are used to show that a test of QCD collinear factorization can be done at the lowest order by measuring scaling laws and angular distributions. The future measurement of the signal channel cross section with PANDA will provide a new test of the perturbative QCD description of a novel class of hard exclusive reactions and will open the possibility of experimentally accessing pi N TDAs.
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