R.A. Carrigan, Jr
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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
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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Single pi+ electroproduction on the proton in the first and second resonance regions at 0.25-GeV**2 < Q**2 < 0.65-GeV**2 using CLAS.

The CLAS collaboration Egiyan, H. ; Aznauryan, I.G. ; Burkert, V.D. ; et al.
Phys.Rev.C 73 (2006) 025204, 2006.
Inspire Record 707883 DOI 10.17182/hepdata.6748

The ep -> e'pi^+n reaction was studied in the first and second nucleon resonance regions in the 0.25 GeV^2 < Q^2 < 0.65 GeV^2 range using the CLAS detector at Thomas Jefferson National Accelerator Facility. For the first time the absolute cross sections were measured covering nearly the full angular range in the hadronic center-of-mass frame. The structure functions sigma_TL, sigma_TT and the linear combination sigma_T+epsilon*sigma_L were extracted by fitting the phi-dependence of the measured cross sections, and were compared to the MAID and Sato-Lee models.

304 data tables
Table 1

Structure functions for Q**2 = 0.30 GeV**2 and W = 1.11 GeV.

Table 2

Structure functions for Q**2 = 0.30 GeV**2 and W = 1.13 GeV.

Table 3

Structure functions for Q**2 = 0.30 GeV**2 and W = 1.15 GeV.

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Measurement of pi- p ---> eta n from threshold to p (pi-) = 747-MeV/c

Prakhov, S. ; Nefkens, B.M.K. ; Allgower, C.E. ; et al.
Phys.Rev.C 72 (2005) 015203, 2005.
Inspire Record 687736 DOI 10.17182/hepdata.25215

The differential cross section for η production in reaction π−p→ηn has been measured over the full angular range at seven incident π− beam momenta from threshold to pπ−=747 MeV/c using the Crystal Ball multiphoton spectrometer. The angular distributions are S wave dominated. At 10 MeV/c above threshold, a small D-wave contribution appears that interferes with the main S wave. The total η production cross section σtot is obtained by integration of dσ/dΩ. Starting at threshold, σtot rises rapidly, as expected for S-wave-dominated production. The features of the π−p→ηn cross section are strikingly similar to those of the SU(3) flavor-related process K−p→ηΛ. Comparison of the π−p→ηn reaction is made with η photoproduction.

3 data tables
Table 1

Total cross sections.

Table 2

Differential cross section for the 4 lowest beam momenta.

Table 3

Differential cross section for the 3 highest beam momenta.


Measurement of the polarized structure function sigma(LT') for pion electroproduction in the Roper resonance region.

The CLAS collaboration Joo, K. ; Smith, L.C. ; Aznauryan, I.G. ; et al.
Phys.Rev.C 72 (2005) 058202, 2005.
Inspire Record 681275 DOI 10.17182/hepdata.25214

The polarized longitudinal-transverse structure function $\sigma_{LT^\prime}$ measures the interference between real and imaginary amplitudes in pion electroproduction and can be used to probe the coupling between resonant and non-resonant processes. We report new measurements of $\sigma_{LT^\prime}$ in the $N(1440){1/2}^+$ (Roper) resonance region at $Q^2=0.40$ and 0.65 GeV$^2$ for both the $\pi^0 p$ and $\pi^+ n$ channels. The experiment was performed at Jefferson Lab with the CEBAF Large Acceptance Spectrometer (CLAS) using longitudinally polarized electrons at a beam energy of 1.515 GeV. Complete angular distributions were obtained and are compared to recent phenomenological models. The $\sigma_{LT^\prime}(\pi^+ n)$ channel shows a large sensitivity to the Roper resonance multipoles $M_{1-}$ and $S_{1-}$ and provides new constraints on models of resonance formation.

58 data tables
Table 1

Polarized structure function of the reaction E- P --> E- PI0 P for Q**2 = 0.40 and W = 1.1 GeV.

Table 2

Polarized structure function of the reaction E- P --> E- PI0 P for Q**2 = 0.40 and W = 1.14 GeV.

Table 3

Polarized structure function of the reaction E- P --> E- PI0 P for Q**2 = 0.40 and W = 1.18 GeV.

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Deeply virtual and exclusive electroproduction of omega mesons.

The CLAS collaboration Morand, L. ; Dore, D. ; Garcon, M. ; et al.
Eur.Phys.J.A 24 (2005) 445-458, 2005.
Inspire Record 681604 DOI 10.17182/hepdata.43499

The exclusive omega electroproduction off the proton was studied in a large kinematical domain above the nucleon resonance region and for the highest possible photon virtuality (Q2) with the 5.75 GeV beam at CEBAF and the CLAS spectrometer. Cross sections were measured up to large values of the four-momentum transfer (-t < 2.7 GeV2) to the proton. The contributions of the interference terms sigma_TT and sigma_TL to the cross sections, as well as an analysis of the omega spin density matrix, indicate that helicity is not conserved in this process. The t-channel pi0 exchange, or more generally the exchange of the associated Regge trajectory, seems to dominate the reaction gamma* p -> omega p, even for Q2 as large as 5 GeV2. Contributions of handbag diagrams, related to Generalized Parton Distributions in the nucleon, are therefore difficult to extract for this process. Remarkably, the high-t behaviour of the cross sections is nearly Q2-independent, which may be interpreted as a coupling of the photon to a point-like object in this kinematical limit.

85 data tables
Table 1

Total cross sections and interference terms (TT and TL).

Table 2

Differential cross sections DSIG/DT for Q**2 = 1.725 GeV**2 and W = 2.77 GeV.

Table 3

Differential cross sections DSIG/DT for Q**2 = 1.752 GeV**2 and W = 2.48 GeV.

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Exclusive rho0 meson electroproduction from hydrogen at CLAS.

The CLAS collaboration Hadjidakis, C. ; Guidal, M. ; Garcon, M. ; et al.
Phys.Lett.B 605 (2005) 256-264, 2005.
Inspire Record 655683 DOI 10.17182/hepdata.41881

The longitudinal and transverse components of the cross section for the $e p\to e^\prime p \rho^0$ reaction were measured in Hall B at Jefferson Laboratory using the CLAS detector. The data were taken with a 4.247 GeV electron beam and were analyzed in a range of $x_B$ from 0.2 to 0.6 and of $Q^2$ from 1.5 to 3.0 GeV$^2$. The data are compared to a Regge model based on effective hadronic degrees of freedom and to a calculation based on Generalized Parton Distributions. It is found that the transverse part of the cross section is well described by the former approach while the longitudinal part can be reproduced by the latter.

5 data tables
Table 1

The ratio of the longitudinal to transverse cross sections for two Q**2 regions.

Table 2

The longitudinal and transverse cross sections as a function of Q**2 for X Bjorken = 0.31.

Table 3

The longitudinal and transverse cross sections as a function of Q**2 for X Bjorken = 0.38.

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Search for first-generation scalar and vector leptoquarks

The D0 collaboration Abazov, V.M. ; Abbott, B. ; Abdesselam, A. ; et al.
Phys.Rev.D 64 (2001) 092004, 2001.
Inspire Record 557085 DOI 10.17182/hepdata.42922

We describe a search for the pair production of first-generation scalar and vector leptoquarks in the eejj and enujj channels by the D0 Collaboration. The data are from the 1992--1996 ppbar run at sqrt{s} = 1.8 TeV at the Fermilab Tevatron collider. We find no evidence for leptoquark production; in addition, no kinematically interesting events are observed using relaxed selection criteria. The results from the eejj and enujj channels are combined with those from a previous D0 analysis of the nunujj channel to obtain 95% confidence level (C.L.) upper limits on the leptoquark pair-production cross section as a function of mass and of beta, the branching fraction to a charged lepton. These limits are compared to next-to-leading-order theory to set 95% C.L. lower limits on the mass of a first-generation scalar leptoquark of 225, 204, and 79 GeV/c^2 for beta=1, 1/2, and 0, respectively. For vector leptoquarks with gauge (Yang-Mills) couplings, 95% C.L. lower limits of 345, 337, and 206 GeV/c^2 are set on the mass for beta=1, 1/2, and 0, respectively. Mass limits for vector leptoquarks are also set for anomalous vector couplings.

3 data tables
Table 1

No description provided.

Table 2

No description provided.

Table 3

No description provided.


Measurement of the cross section asymmetry of the reaction gamma p --> pi0 p in the resonance energy region E(gamma) = 0.5-GeV - 1.1-GeV.

Adamian, F.V. ; Bunyatyan, A.Yu. ; Frangulian, G.S. ; et al.
Phys.Rev.C 63 (2001) 054606, 2001.
Inspire Record 536542 DOI 10.17182/hepdata.31424

The cross section asymmetry Sigma has been measured for the photoproduction of pi0-mesons off protons, using polarized photons in the energy range Eg = 0.5 - 1.1 GeV. The CM angular coverage is Theta = 85 - 125 deg with energy and angle steps of 25 MeV and 5 deg, respectively. The obtained Sigma data, which cover the second and third resonance regions, are compared with existing experimental data and recent phenomenological analyses. The influence of these measurements on such analyses is also considered.

9 data tables
Table 1

Axis error includes +- 3/3 contribution (Due to accuracy of the linear polarization calculations).

Table 2

Axis error includes +- 3/3 contribution (Due to accuracy of the linear polarization calculations).

Table 3

Axis error includes +- 3/3 contribution (Due to accuracy of the linear polarization calculations).

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Antineutron proton total cross section from 50-MeV/c to 400-MeV/c.

The OBELIX collaboration Iazzi, F. ; Feliciello, A. ; Agnello, M. ; et al.
Phys.Lett.B 475 (2000) 378-385, 2000.
Inspire Record 527242 DOI 10.17182/hepdata.28048

The antineutron–proton total cross section has been measured in the low momentum range 50–400 MeV/ c (below 100 MeV/ c for the first time). The measurement was performed at LEAR (CERN) by the OBELIX experiment, thanks to its unique antineutron beam facility. A thick target transmission technique has been used. The measured total cross section shows an anomalous behaviour below 100 MeV/ c . A dominance of the isospin I =0 channel over the I =1 one at low energy is clearly deduced.

1 data table
Table 1

Measured values of the total cross section.


Search for second generation leptoquark pairs in anti-p p collisions at S**(1/2) = 1.8-TeV

The D0 collaboration Abbott, B. ; Abolins, M. ; Abramov, V. ; et al.
Phys.Rev.Lett. 84 (2000) 2088-2093, 2000.
Inspire Record 508772 DOI 10.17182/hepdata.42087

We have searched for second generation leptoquark (LQ) pairs in the \mu\mu+jets channel using 94+-5 pb^{-1} of pbar-p collider data collected by the D0 experiment at the Fermilab Tevatron during 1993-1996. No evidence for a signal is observed. These results are combined with those from the \mu\nu+jets and \nu\nu+jets channels to obtain 95% confidence level (C.L.) upper limits on the LQ pair production cross section as a function of mass and $beta, the branching fraction of a LQ decay into a charged lepton and a quark. Lower limits of 200(180) GeV/c^2 for \beta=1(1/2) are set at the 95% C.L. on the mass of scalar LQ. Mass limits are also set on vector leptoquarks as a function of \beta.

1 data table
Table 1

No description provided.