Stephan L. Mintz

The reaction e− + p → Λ + ν and the contributions of the individual form factors to the differential cross section

Abstract We calculate the differential cross section for the weak, strangeness changing, electron scattering process, e− + p → Λ + ν, for incoming electron energies of 0.5, 1.0, 2.0, 4.0, and 6.0 GeV. We obtain as well contributions of the individual form factors to the differential cross sections. We find that the differential cross sections peak as the maximal scattering angle for the Λ is approached and that the peak height increases as the electron energy is increased. The behavior of the differential cross section near the maximal angle is discussed as is the possibility of observing this reaction in a facility such as TJNAF.

The reaction e− + 3He → νe + 3H and the determination of the weak nuclear form factors

Abstract We calculate the differential cross section for the weak electron scattering process, e − + 3 He → ν e + 3 H , for a variety of energies from 0.1 to 6.0 GeV. We note that the maximum of the differential cross section increases with increasing electron energy but that the width of the peak at half maximum rapidly shrinks. The contributions of the individual nuclear form factors to the cross section are also obtained and the possibility of determining them via electron accelerator experiments is discussed.

Polarized parity violating electron scattering on 3He

Abstract We calculate the asymmetry parameters, A, and figures-of-merit for polarized parity violating electron scattering from 3He via the reaction, e− +3 He → e− +3 He. We do this explicitly forv incident electron energies of 1.0 GeV and 4.0 GeV. We find a sharp and unexpected variation in A due to cancellations between the weak and electromagnetic form factors caused by the different q2 dependences of these form factors. We find that at small angles, the asymmetry may be obtained to reasonably high accuracy for all energies considered and that the interesting region where the asymmetry has its first maximum and minimum is accessible for electron energies of 1 GeV or higher. In addition we find that the asymmetry and figures-of-merit are in the range of those for other proposed target nuclei. We also consider the possibility of strange quark contributions to the asymmetry and show that at the first maxima and minima, possible contributions of the strange quark current vector form factors cause large variations in the asymmetry which might be observed.

Polarized parity violating electron scattering in 3He and 3H

We calculate the asymmetry parameter, A, for the electron scattering reaction, e+3He→e+3He, run with right and left handed polarized electrons. We have calculated this reaction at energies from .1 GeV to 6 GeV. We present here the results for this reaction run at 1 GeV as an example. We obtain both A and a figure of merit. We find a sharp and unexpected variation in A due to cancellation between the weak and electromagnetic form factors. This is caused by the different q2 dependences of the weak and electromagnetic form factors. Unfortunately in this region the figure of merit is small.

The Production of Λ and Σ0 Hyperons in Antineutrino‐Proton Collisions

We obtain total and differential cross sections for the strangeness changing charged current reactions, νL + p → Λ + L+ and νL + p → Σ0 + L+ where L stands for an electron, muon, or tau lepton. We calculate these cross sections from near threshold to several GeV. We also obtain the the contributions of the various form factors to the total and differential cross sections. We do this in support of possible experiments which have been proposed by the MINERνA Collaboration. The calculation is phenomenologically based and makes use of SU(3) relations to obtain the standard vector form factors. The axial current form factor for the Λ reaction is obtained via Λ beta decay data but for the Σ0 process is obtained via SU(2) relations from Σ− beta decay data since Σ0 does not undergo beta decay. We also make use of theoretical estimates for the contribution of the pseudoscalar form factor and for the FE and FS form factors to the processes described here. We note that the latter two form factors are second class ...

The Weak Production of Lambda Particles in Electron and Muon Scattering from Protons from Near Threshold to the 5.0 GeV Region

We calculate the differential cross sections for the weak strangeness changing reactions e− + p → Λ + ve and μ− + p → vμ + Λ. We study the former reaction for energies near threshold and we study the later reaction from energies near threshold to 5.0 GeV. We do this because the electron induced reaction has been proposed as possible experiment at the Thomas Jefferson National Accelerator Facility by which the electron neutrino mass might be measured. We study the muon induced reaction over a wider range of energies because it might be used to study form factors which are more difficult or impossible to observe in an electron induced reactions due to the small size of the electron mass. In particular we obtain the induced pseudoscalar form factor contributions to the differential cross section as well as the contributions of the FE and FS form factors to try to determine if it is feasible to observe them. We use an SU(3) based semi‐phenomenological calculation to obtain the form factors from electron scatt...

Inclusive Neutrino and Antineutrino Reactions in Iron and an Interesting Relation

Neutrino reactions in nuclei are very interesting for a number of reasons. They present us with the very few opportunities which we have for studying neutrino reactions in a laboratory setting under controlled conditions. In particular iron is an unusually suitable reaction to study. Virtually every neutrino experiment has some background from iron used in shielding or for tanks and other equipment. This is particularly true for the KARMEN experiments1 which make use of a 6000 ton steel shield for their calorimeter. The KARMEN collaboration2 considers neutrino reactions in iron to be one of its most serious backgrounds. They have extracted some results for electron neutrino cross sections on 56Fe averaged over the Michel spectrum which have been already published3,4. The interest in neutrino reactions in iron however is not merely as a background. There has been an experiment involving high energy neutrino and antineutrino reactions in iron5. Furthermore there is a new experiment6 for neutrino reactions in iron which will start in the near future and will run from threshold to about 3 GeV. These experiments both planned and already performed will provide useful information on how present calculations, which seem to work well for neutrino reactions in 12C up to a few hundred MeV might be extended. In particular it may be possible to make use of already determined structure functions to extend our present calculations. Besides obtaining the cross sections for the reactions ve +56 Fe → e+X,vμ+56Fe → μ+X,ve,+56Fe → e+X , and vμ+Fe → μ+X , _

Neutrino Reactions in Nuclei and a Connection to the Neutron Number

We compare the inclusive electron neutrino cross sections, ve + Ni → X + e−, averaged over the Michel spectrum for 12C,13C,56Fe and 127I. We use 56Fe as a model and present a number of results for this nucleus. We choose these nuclei because terrestrial measurements at LSND and KARMEN have been undertaken for them and these measurements are in reasonable agreement with calculated values. We show that the cross sections increase linearly with neutron number for these nuclei and discuss what this might imply.

The Reaction μ− + p → Λ + vμ and the Contributions of the Pseudoscalar Form Factor

We calculate the differential cross section for the weak, strangeness changing, muon scattering process, μ− + p → vμ + Λ, for incoming muon energies of 2.0,0.275 and 0.265 GeV. We obtain as well contributions of the individual form factors to the differential cross sections but focus on the pseudocalar form factor which has not been well studied in strangeness changing processes. In particular we assess the possibility of observing pseudoscalar form factor contributions at low q2 where the mass of the muon may accentuate these contributions. We find that the differential cross sections peak as the maximal scattering angle for the Λ is approached and that the peak height increases as the muon energy is increased. The behavior of the differential cross section near the maximal angle is discussed as is the possibility of observing second class current form factors.

Hyperon electroproduction and strangeness physics

We calculate the differential cross section for the weak production of Λ and Σ0 hyperons via electron scattering from protons for a range of incident electron energies from 0.5 to 6.0 GeV. The calculations presented are phenomenologically based and make use of SU(3)and SU(2) relations. We obtain contributions from individual form factors to the differential cross sections and calculate the expected event rates for these reactions. We show that Λ production should be observable and that Σ0 production, though smaller might be observable. Finally we discuss what might be learned about the structure of the weak, strangeness changing current from these two processes as well as how these processes might serve as tests of SU(3) relations.