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Differential cross section and recoil polarization measurements for the gamma p to K+ Lambda reaction using CLAS at Jefferson Lab

The CLAS collaboration McCracken, M.E. ; Bellis, M. ; Meyer, C.A. ; et al.
Phys.Rev.C 81 (2010) 025201, 2010.
Inspire Record 840934 DOI 10.17182/hepdata.54967

We present measurements of the differential cross section and Lambda recoil polarization for the gamma p to K+ Lambda reaction made using the CLAS detector at Jefferson Lab. These measurements cover the center-of-mass energy range from 1.62 to 2.84 GeV and a wide range of center-of-mass K+ production angles. Independent analyses were performed using the K+ p pi- and K+ p (missing pi -) final-state topologies/ results from these analyses were found to exhibit good agreement. These differential cross section measurements show excellent agreement with previous CLAS and LEPS results and offer increased precision and a 300 MeV increase in energy coverage. The recoil polarization data agree well with previous results and offer a large increase in precision and a 500 MeV extension in energy range. The increased center-of-mass energy range that these data represent will allow for independent study of non-resonant K+ Lambda photoproduction mechanisms at all production angles.

241 data tables match query
Table 1

Differential cross section as a function of COS(THETA(K)) for the centre-of-mass range 1.62-1.63 GeV.

Table 2

Differential cross section as a function of COS(THETA(K)) for the centre-of-mass range 1.63-1.64 GeV.

Table 3

Differential cross section as a function of COS(THETA(K)) for the centre-of-mass range 1.64-1.65 GeV.

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Separated structure functions for the exclusive electroproduction of K+ Lambda and K+ Sigma0 final states.

The CLAS collaboration Ambrozewicz, P. ; Carman, D.S. ; Feuerbach, R.J. ; et al.
Phys.Rev.C 75 (2007) 045203, 2007.
Inspire Record 732363 DOI 10.17182/hepdata.4994

We report measurements of the exclusive electroproduction of $K^+\Lambda$ and $K^+\Sigma^0$ final states from a proton target using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The separated structure functions $\sigma_T$, $\sigma_L$, $\sigma_{TT}$, and $\sigma_{LT}$ were extracted from the $\Phi$- and $\epsilon$-dependent differential cross sections taken with electron beam energies of 2.567, 4.056, and 4.247 GeV. This analysis represents the first $\sigma_L/\sigma_T$ separation with the CLAS detector, and the first measurement of the kaon electroproduction structure functions away from parallel kinematics. The data span a broad range of momentum transfers from $0.5\leq Q^2\leq 2.8$ GeV$^2$ and invariant energy from $1.6\leq W\leq 2.4$ GeV, while spanning nearly the full center-of-mass angular range of the kaon. The separated structure functions reveal clear differences between the production dynamics for the $\Lambda$ and $\Sigma^0$ hyperons. These results provide an unprecedented data sample with which to constrain current and future models for the associated production of strangeness, which will allow for a better understanding of the underlying resonant and non-resonant contributions to hyperon production.

531 data tables match query
Table 1

Cross sections for incident energy 2.567 GeV for the Q**2 range 0.5 to 0.8 GeV**2 and W range 1.6 to 1.7 GeV.

Table 2

Cross sections for incident energy 2.567 GeV for the Q**2 range 0.5 to 0.8 GeV**2 and W range 1.70 to 1.75 GeV.

Table 3

Cross sections for incident energy 2.567 GeV for the Q**2 range 0.5 to 0.8 GeV**2 and W range 1.75 to 1.80 GeV.

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Measurements of Delta sigma-L (n p) between 500-MeV and 800-MeV

Beddo, M. ; Burleson, G. ; Faucett, J.A. ; et al.
Phys.Lett.B 258 (1991) 24-28, 1991.
Inspire Record 29058 DOI 10.17182/hepdata.51096

A measurement of Δσ L (np), the difference between neutron-proton total cross sections in pure longitudinal spin states, is described. Data were taken for five energies between 500 and 800 MeV, with statistical errors of ≈ 1.5 mb and an estimated normalization error of 6%. The data, combined with other results, show some evidence for an elastic I =0 spin-singlet resonance with mass ∼ 2213 MeV and width ∼ 74 MeV, or a coupled-triplet resonance with similar mass and width.

1 data table match query
Table 1

SIG(C=PARALLEL)-SIG(C=ANTIPARALLEL) means the difference in the total crosssection with initial parallel and antiparallel longitudinal spin states. The I0 means I=0, these values were found using interpolated Delta(sigma(pp)) data.


Measurement of gamma p --> K+ Lambda and gamma p --> K+ Sigma0 at photon energies up to 2.6 GeV

Glander, K.H. ; Barth, J. ; Braun, W. ; et al.
Eur.Phys.J.A 19 (2004) 251-273, 2004.
Inspire Record 626695 DOI 10.17182/hepdata.51677

The reactions gamma p --> K+ Lambda and gamma p --> K+ Sigma0 were measured in the energy range from threshold up to a photon energy of 2.6 GeV. The data were taken with the SAPHIR detector at the electron stretcher facility, ELSA. Results on cross sections and hyperon polarizations are presented as a function of kaon production angle and photon energy. The total cross section for Lambda production rises steeply with energy close to threshold, whereas the Sigma0 cross section rises slowly to a maximum at about E_gamma = 1.45 GeV. Cross sections together with their angular decompositions into Legendre polynomials suggest contributions from resonance production for both reactions. In general, the induced polarization of Lambda has negative values in the kaon forward direction and positive values in the backward direction. The magnitude varies with energy. The polarization of Sigma0 follows a similar angular and energy dependence as that of Lambda, but with opposite sign.

24 data tables match query
Table 1

Differential cross sections for the reaction GAMMA P --> K+ LAMBDA in the energy region 0.9 to 1.0 GeV.

Table 2

Differential cross sections for the reaction GAMMA P --> K+ LAMBDA in the energy region 1.0 to 1.2 GeV.

Table 3

Differential cross sections for the reaction GAMMA P --> K+ LAMBDA in the energy region 1.2 to 1.4 GeV.

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Measurement of the polarization parameter of the reactions pi- p ---> pi0 n and eta n at 5 and 8 gev/c

Bonamy, P. ; Borgeaud, P. ; Crozon, M. ; et al.
Nucl.Phys.B 52 (1973) 392-402, 1973.
Inspire Record 84261 DOI 10.17182/hepdata.50104

Measurements of the polarization parameter of the reactions π − p → π 0 n and π − p → η n at 4.90 and 7.85 GeV/ c and for a squared four-momentum transfer − t ranging from 0.1 to 2.0 (GeV/ c ) 2 have been achieved by using a butanol polarized proton target and detecting only the two γ's from the neutral meson decay. The background due to events involving bound protons has been separately measured and subtracted out. A large positive polarization has been found for the reaction π − p → π 0 n. It is consistent with other pion-nucleon scattering data connected by isospin conservation. The polarization for the reaction π − p → η n is not significantly different from zero within the large experimental errors.

2 data tables match query
Table 1

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Table 2

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Linearly polarised photon beams at ELSA and measurement of the beam asymmetry in pi^0-photoproduction off the proton

The CBELSA & TAPS collaborations Elsner, D. ; Bantes, B. ; Bartholomy, O. ; et al.
Eur.Phys.J.A 39 (2009) 373-381, 2009.
Inspire Record 799078 DOI 10.17182/hepdata.50479

At the electron accelerator ELSA a linearly polarised tagged photon beam is produced by coherent bremsstrahlung off a diamond crystal. Orientation and energy range of the linear polarisation can be deliberately chosen by accurate positioning of the crystal with a goniometer. The degree of polarisation is determined by the form of the scattered electron spectrum. Good agreement between experiment and expectations on basis of the experimental conditions is obtained. Polarisation degrees of P = 40% are typically achieved at half of the primary electron energy. The determination of P is confirmed by measuring the beam asymmetry, \Sigma, in pi^0 photoproduction and a comparison of the results to independent measurements using laser backscattering.

20 data tables match query
Table 1

Beam asymmetry as a function of the PI0 centre of mass scattering angle.

Table 2

Beam asymmetry as a function of the PI0 centre of mass scattering angle.

Table 3

Beam asymmetry as a function of the PI0 centre of mass scattering angle.

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Left-right Asymmetry in Inverse $\pi^-$ Photoproduction From a Transversely Polarized Proton Target

Kim, G.J. ; Adrian, S.D. ; Arends, J. ; et al.
Phys.Rev.Lett. 56 (1986) 1779-1782, 1986.
Inspire Record 232117 DOI 10.17182/hepdata.20259

Accurate measurements of the left-right asymmetry in π−p→γn at pπ=427−625 MeV/c with a transversely polarized target are reported. Results are compared with the predictions from the Arai and Fujii single-pion photoproduction partial-wave analysis and with data on the inverse process measured with a deuterium target. The agreement is poor, casting doubt on the correctness of the value for the radiative-decay amplitude of the neutral Roper resonance now in use.

5 data tables match query
Table 1

No description provided.

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Polarized target asymmetry in pion proton bremsstrahlung at 298-MeV

Bosshard, A. ; Amsler, Claude ; Bistirlich, J.A. ; et al.
Phys.Rev.Lett. 64 (1990) 2619-2622, 1990.
Inspire Record 303404 DOI 10.17182/hepdata.22827

First data are presented for the polarized-target asymmetry in the reaction π+p→π+pγ at an incident pion energy of 298 MeV. The geometry was chosen to maximize the sensitivity to the radiation of the magnetic dipole moment μΔ of the Δ++(1232 MeV). A fit of the asymmetry in the cross section d5σ/dΩπ dΩγ dk as a function of the photon energy k to predictions from a recent isobar-model calculation with μΔ as the only free parameter yields μΔ=1.64(±0.19expΔ,±0.14 theor)μp. Though this value agrees with bag-model corrections to the SU(6) prediction μΔ=2μp, further clarifications on the model dependence of the result are needed, in particular since the isobar model fails to describe both the cross section and the asymmetry at the highest photon energies.

2 data tables match query
Table 1

No description provided.

Table 2

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Analyzing power measurement of p p elastic scattering in the Coulomb - nuclear interference region with the 200-GeV/c polarized proton beam at Fermilab

The E581/704 collaboration Akchurin, N. ; Langland, J. ; Onel, Y. ; et al.
Phys.Rev.D 48 (1993) 3026-3036, 1993.
Inspire Record 364576 DOI 10.17182/hepdata.22670

The analyzing power AN of proton-proton elastic scattering in the Coulomb-nuclear interference region has been measured using the 200-GeV/c Fermilab polarized proton beam. A theoretically predicted interference between the hadronic non-spin-flip amplitude and the electromagnetic spin-flip amplitude is shown for the first time to be present at high energies in the region of 1.5 × 10−3 to 5.0 × 10−2 (GeV/c)2 four-momentum transfer squared, and our results are analyzed in connection with theoretical calculations. In addition, the role of possible contributions of the hadronic spin-flip amplitude is discussed.

1 data table match query
Table 1

No description provided.


Negative-pion photoproduction from neutrons by linearly polarized photons in the first resonance region

Kondo, K. ; Miyachi, T. ; Ukai, K. ; et al.
Phys.Rev.D 9 (1974) 529-533, 1974.
Inspire Record 93115 DOI 10.17182/hepdata.21954

The angular dependence of the asymmetry for negative-pion photoproduction on neutrons by linearly polarized photons has been measured for photon energies 260, 300, 350, 400, 450, and 500 MeV at center-of-mass angles 60°, 75°, 90°, 150°, and 120°. The results are compared with theoretical models of low-energy single-pion photoproduction. The observed asymmetry below 400 MeV shows good agreement with predictions of dispersion-theoretical models by Berends, Donnachie, and Weaver and by Schwela. The asymmetry values in the 400-500 MeV energy region suggest that smaller M1− amplitude is more favorable.

6 data tables match query
Table 1

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