Bisello, D.
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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
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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Mechanism of the close-to-threshold production of the eta meson.

Czyzykiewicz, R. ; Moskal, P. ; Adam, H.-H. ; et al.
Phys.Rev.Lett. 98 (2007) 122003, 2007.
Inspire Record 731185 DOI 10.17182/hepdata.41775

Measurements of the analysing power for the p(pol)p --> ppeta reaction have been performed in the close-to-threshold energy region at beam momenta of p_{beam}=2.010 and 2.085 GeV/c, corresponding to excess energies of Q=10 and 36 MeV, respectively. The determined analysing power is essentially consistent with zero implying that the eta meson is produced predominantly in the s-wave at both excess energies. The angular dependence of the analysing power, combined with the hitherto determined isospin dependence of the total cross section for the eta meson production in nucleon-nucleon collisions, reveal a statistically significant indication that the excitation of the nucleon to the S_{11}(1535) resonance, the process which intermediates the production of the eta meson, is predominantly due to the exchange of the pi meson between the colliding nucleons.

2 data tables
Table 1

Analysing power measurements for excess energy 10 MeV.

Table 2

Analysing power measurements for excess energy 36 MeV.


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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Measurement of the reaction gamma p --> K0 Sigma+ at photon energies up to 2.6-GeV.

Lawall, R. ; Barth, J. ; Bennhold, C. ; et al.
Eur.Phys.J.A 24 (2005) 275-286, 2005.
Inspire Record 680746 DOI 10.17182/hepdata.43595

The reaction gamma p --> K0 Sigma+ was measured in the photon energy range from threshold up to 2.6 GeV with the SAPHIR detector at the electron stretcher facility, ELSA, in Bonn. Results are presented on the reaction cross section and the polarization of the Sigma+ as a function of the kaon production angle in the centre-of-mass system, cos(Theta_K^{c.m.}), and the photon energy. The cross section is lower and varies less with photon energy and kaon production angle than that of gamma p --> K+ Sigma0. The Sigma+ is polarized predominantly at cos(Theta_K^{c.m.}) \approx 0. The data presented here are more precise than previous ones obtained with SAPHIR and extend the photon energy range to higher values. They are compared to isobar model calculations.

14 data tables
Table 1

Axis error includes +- 10/10 contribution (Normalization uncertainty already included.).

Table 2

Axis error includes +- 10/10 contribution (Normalization uncertainty already included.).

Table 3

Axis error includes +- 10/10 contribution (Normalization uncertainty already included.).

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Exclusive eta production in proton-proton reactions.

Balestra, F. ; Bedfer, Y. ; Bertini, R. ; et al.
Phys.Rev.C 69 (2004) 064003, 2004.
Inspire Record 653991 DOI 10.17182/hepdata.25225

Differential cross sections for the exclusive reaction p⃗p→ppη observed via the η→π+π−π0 decay channel have been measured at Tbeam=2.15GeV, 2.50GeV, and 2.85GeV (excess energies 324MeV, 412MeV, and 554MeV). The influence of the N(1535)S11 resonance is clearly seen in the invariant mass and momentum dependent differential cross sections. The extracted resonance parameters are compatible with existing data. No significant evidence for further resonance contributions has been found. In addition, angular distributions of the ppη final state have been measured. The polar angle distribution of the η shows an anisotropy with respect to the beam axis for the lowest beam energy, which vanishes for the higher energies. The sign of this anisotropy is negative and expected to be sensitive to the dominant production mechanism. In contrast, the proton polar angle in the pp rest frame tends to be more strongly aligned along the beam axis with increasing beam energy. The analyzing power Ay is compatible with zero for all beam energies.

8 data tables
Table 1

Differential cross section for incident kinetic energy 2.15 GeV, divided by the phase space as a function of the invariant mass of the ETA and the final state proton with the lower value of ABS(T). This is proportional to the square of the decay matrix element ABS(M)**2 of the P-ETA system.

Table 2

Differential cross section for incident kinetic energy 2.50 GeV, divided by the phase space as a function of the invariant mass of the ETA and the final state proton with the lower value of ABS(T). This is proportional to the square of the decay matrix element ABS(M)**2 of the P-ETA system.

Table 3

Differential cross section for incident kinetic energy 2.85 GeV, divided by the phase space as a function of the invariant mass of the ETA and the final state proton with the lower value of ABS(T). This is proportional to the square of the decay matrix element ABS(M)**2 of the P-ETA system.

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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
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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Analysing power A(y) in the reaction p(pol.) p --> p p eta close to threshold.

Winter, P. ; Adam, H.H. ; Bauer, F. ; et al.
Phys.Lett.B 544 (2002) 251-258, 2002.
Inspire Record 599591 DOI 10.17182/hepdata.31686

Measurements of the eta meson production with a polarised proton beam in the reaction p(pol) p --> p p eta have been carried out at an excess energy of Q = 40 MeV. The dependence of the analysing power A_y on the polar angle theta^*_q of the eta meson in the center of mass system (CMS) has been studied. The data indicate the possibility of an influence of p- and d-waves to the close to threshold eta production.

1 data table
Table 1

Averaged value of the analyzing power and cross section as a function of the emmission angle of the ETA meson is the CM system.


Measurement of the Antilambda polarization in nu/mu charged current interactions in the NOMAD experiment.

The NOMAD collaboration Astier, P. ; Autiero, D. ; Baldisseri, A. ; et al.
Nucl.Phys.B 605 (2001) 3-14, 2001.
Inspire Record 554759 DOI 10.17182/hepdata.48928

We present a measurement of the polarization of Antilambda hyperons produced in nu_mu charged current interactions. The full data sample from the NOMAD experiment has been analyzed using the same V0 identification procedure and analysis method reported in a previous paper for the case of Lambda hyperons. The Antilambda polarization has been measured for the first time in a neutrino experiment. The polarization vector is found to be compatible with zero.

2 data tables
Table 1

Lambdabar polarization in regions of Feynman X (XL).

Table 2

Lambdabar polarization in regions of the Bjorken scaling variable X.


Excitation functions of the analyzing power in p p(pol.) scattering from 0.45-GeV to 2.5-GeV

The EDDA collaboration Altmeier, M. ; Bauer, F. ; Bisplinghoff, J. ; et al.
Phys.Rev.Lett. 85 (2000) 1819-1822, 2000.
Inspire Record 537773 DOI 10.17182/hepdata.19490

Excitation functions AN(pp,Θc.m.) of the analyzing power in pp→ elastic scattering have been measured with a polarized atomic hydrogen target for projectile momenta pp between 1000 and 3300 MeV/ c. The experiment was performed for scattering angles 30°≤Θc.m.≤90° using the recirculating beam of the proton storage ring COSY during acceleration. The resulting excitation functions and angular distributions of high internal consistency have significant impact on the recent phase shift solution SAID SP99, in particular, on the spin triplet phase shifts between 1000 and 1800 MeV, and demonstrate the limited predictive power of single-energy phase shift solutions at these energies.

26 data tables
Table 1

No description provided.

Table 2

No description provided.

Table 3

No description provided.

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Measurement of spin observables in neutron proton elastic scattering. I: Correlation parameters

Arnold, J. ; van den Brandt, B. ; Daum, M. ; et al.
Eur.Phys.J.C 17 (2000) 67-81, 2000.
Inspire Record 537914 DOI 10.17182/hepdata.43392

The spin correlation parameters$A_{oonn}, A_{ooss}, A_{oosk}, A_{ookk}$and the analyzing power$A_{oono}$have been measured i

6 data tables
Table 1

Values of the coefficients for the linear combinations of the spin correlation parameters Cpq measurements for the four different beam and target polarisation orientations. For the (z,z) and (y,y) configurations the coefficients are identical for all incident kinetic energies.

Table 2

Measurement of the analysing power. Statistical errors only are shown. For the systematic errors see the systematics section above. Note that there are two overlapping angular settings.

Table 3

Measurements of the spin correlation parameter CNN. Statistical errors onlyare shown. For the systematics see the systematic section above. Note the two overlapping angular settings.

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