Giacomelli, G.
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On the Production of $\pi^+\pi^+$ Pairs in pp Collisions at 0.8 GeV

The COSY-TOF collaboration Abd El-Samad, S. ; Bilger, R. ; Brinkmann, K.-Th. ; et al.
Eur.Phys.J.A 42 (2009) 159-161, 2009.
Inspire Record 823367 DOI 10.17182/hepdata.52421

Data accumulated recently for the exclusive measurement of the $pp\to pp\pi^+\pi^-$ reaction at a beam energy of 0.793 GeV using the COSY-TOF spectrometer have been analyzed with respect to possible events from the $pp \to nn\pi^+\pi^+$ reaction channel. The latter is expected to be the only $\pi\pi$ production channel, which contains no major contributions from resonance excitation close to threshold and hence should be a good testing ground for chiral dynamics in the $\pi\pi$ production process. No single event has been found, which meets all conditions for being a candidate for the $pp \to nn \pi^+\pi^+$ reaction. This gives an upper limit for the cross section of 0.16 $\mu$b (90% C.L.), which is more than an order of magnitude smaller than the cross sections of the other two-pion production channels at the same incident energy.

1 data table
Table 1

Upper limit to the P P --> N N PI+ PI+ cross section.


Events with Isolated Leptons and Missing Transverse Momentum and Measurement of W Production at HERA

The H1 collaboration Aaron, F.D. ; Alexa, C. ; Andreev, V. ; et al.
Eur.Phys.J.C 64 (2009) 251-271, 2009.
Inspire Record 810292 DOI 10.17182/hepdata.53047

Events with high energy isolated electrons, muons or tau leptons and missing transverse momentum are studied using the full e^\pm p data sample collected by the H1 experiment at HERA, corresponding to an integrated luminosity of 474 pb^{-1}. Within the Standard Model, events with isolated leptons and missing transverse momentum mainly originate from the production of single W bosons. The total single W boson production cross section is measured as 1.14 \pm 0.25 (stat.) \pm 0.14 (sys.) pb, in agreement with the Standard Model expectation. The data are also used to establish limits on the WW\gamma gauge couplings and for a measurement of the W boson polarisation.

2 data tables
Table 1

Total single W boson production cross section.

Table 2

Differential single W boson production cross section.


Cross-Sections of Large-Angle Hadron Production in Proton- and Pion-Nucleus Interactions III: Tantalum Nuclei and Beam Momenta from +/-3 Gev/c to +/-15 Gev/c

The HARP-CDP collaboration Bolshakova, A. ; Boyko, I. ; Chelkov, G. ; et al.
Eur.Phys.J.C 63 (2009) 549-609, 2009.
Inspire Record 822058 DOI 10.17182/hepdata.50528

We report on double-differential inclusive cross-sections of the production of secondary protons, charged pions, and deuterons, in the interactions with a 5% nuclear interaction length thick stationary tantalum target, of proton and pion beams with momentum from +/-3 GeV/c to +/-15 GeV/c. Results are given for secondary particles with production angles between 20 and 125 degrees. They are of particular relevance for the optimization of the design parameters of the proton driver of a neutrino factory.

375 data tables
Table 1

Measured cross section as a function of PT for P production from a P beam of momentum 3 GeV/c in the angular range 20 to 30 DEG.

Table 2

Measured cross section as a function of PT for P production from a P beam of momentum 3 GeV/c in the angular range 30 to 40 DEG.

Table 3

Measured cross section as a function of PT for P production from a P beam of momentum 3 GeV/c in the angular range 40 to 50 DEG.

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Measurement of the t anti-t Production Cross Section in 2 fb**-1 of p anti-p Collisions at s**(1/2) =1.96-TeV Using Lepton Plus Jets Events with Soft Muon b-Tagging

The CDF collaboration Aaltonen, T. ; Adelman, Jahred A. ; Akimoto, T. ; et al.
Phys.Rev.D 79 (2009) 052007, 2009.
Inspire Record 811890 DOI 10.17182/hepdata.57018

We present a measurement of the $\ttbar$ production cross section in $\ppbar$ collisions at $\sqrt{s}=1.96$ TeV using events containing a high transverse momentum electron or muon, three or more jets, and missing transverse energy. Events consistent with $\ttbar$ decay are found by identifying jets containing candidate heavy-flavor semileptonic decays to muons. The measurement uses a CDF Run II data sample corresponding to $2 \mathrm{fb^{-1}}$ of integrated luminosity. Based on 248 candidate events with three or more jets and an expected background of $79.5\pm5.3$ events, we measure a production cross section of $9.1\pm 1.6 \mathrm{pb}$.

1 data table
Table 1

Measured cross section assuming a top quark mass of 175 GeV. The second systematic error is the uncertainty on the luminosity.


rivet Analysis
Measurement of D+- and D0 production in deep inelastic scattering using a lifetime tag at HERA

The ZEUS collaboration Chekanov, S. ; Derrick, M. ; Magill, S. ; et al.
Eur.Phys.J.C 63 (2009) 171-188, 2009.
Inspire Record 810112 DOI 10.17182/hepdata.51856

The production of D+- and D0 mesons has been measured with the ZEUS detector at HERA using an integrated luminosity of 133.6 pb-1. The measurements cover the kinematic range 5 < Q^2 < 1000 GeV^2, 0.02 < y < 0.7, 1.5 < p_T^D < 15 GeV and eta^D < 1.6. Combinatorial background to the D meson signals is reduced by using the ZEUS microvertex detector to reconstruct displaced secondary vertices. Production cross sections are compared with the predictions of next-to-leading-order QCD which is found to describe the data well. Measurements are extrapolated to the full kinematic phase space in order to obtain the open-charm contribution, F2^ccbar, to the proton structure function, F2.

21 data tables
Table 1

Production cross section for (D+ + D-) mesons.

Table 2

Production cross section for (D0 + DBAR0) mesons not originating from D*+- decays.

Table 3

Measured D+- cross section as a function of Q**2.

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V^0 production in p+A collisions at \sqrt{s} = 41.6 GeV

The HERA-B collaboration Abt, I. ; Adams, M. ; Agari, M. ; et al.
Eur.Phys.J.C 61 (2009) 207-221, 2009.
Inspire Record 810078 DOI 10.17182/hepdata.52478

Inclusive doubly differential cross sections d^2\sigma_{pA}/dx_Fdp_T^2 as a function of Feynman-x (x_F) and transverse momentum (p_T) for the production of K^0_s, Lambda^0 and anti-Lambda^0 in proton-nucleus interactions at 920 GeV are presented. The measurements were performed by HERA-B in the negative x_F range (-0.12<x_F<0.0) and for transverse momenta up to p_T= 1.6 GeV/c. Results for three target materials: carbon, titanium and tungsten are given. The ratios of production cross sections are presented and discussed. The Cronin effect is clearly observed for all three V^0 species. The atomic number dependence is parameterized as \sigma_{pA} = \sigma_{pN} \cdot A^\alpha where \sigma_{pN} is the proton-nucleon cross section. The measured values of \alpha are all near one. The results are compared with EPOS 1.67 and PYTHIA 6.3. EPOS reproduces the data to within \approx 20% except at very low transverse momentum.

12 data tables
Table 1

Visible cross sections for K0S production in acceptance of the measurement.

Table 2

Visible cross sections for K0S production in acceptance of the measurement.

Table 3

Visible cross sections for K0S production in acceptance of the measurement.

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Measurement of the Inclusive ep Scattering Cross Section at Low $Q^2$ and x at HERA

The H1 collaboration Aaron, F.D. ; Alexa, C. ; Andreev, V. ; et al.
Eur.Phys.J.C 63 (2009) 625-678, 2009.
Inspire Record 817368 DOI 10.17182/hepdata.52425

A measurement of the inclusive ep scattering cross section is presented in the region of low momentum transfers, 0.2 GeV^2 < Q^2 < 12 GeV^2, and low Bjorken x, 5x10^-6 < x < 0.02. The result is based on two data sets collected in dedicated runs by the H1 Collaboration at HERA at beam energies of 27.6 GeV and 920 GeV for positrons and protons, respectively. A combination with data previously published by H1 leads to a cross section measurement of a few percent accuracy. A kinematic reconstruction method exploiting radiative ep events extends the measurement to lower Q^2 and larger x. The data are compared with theoretical models which apply to the transition region from photoproduction to deep inelastic scattering.

39 data tables
Table 1

Reduced cross section as measured in the SVX data sample for Q**2 = 0.20 GeV**2. Additional 3 PCT luminosity uncertainty not included in the total error.

Table 2

Reduced cross section as measured in the SVX data sample for Q**2 = 0.25 GeV**2. Additional 3 PCT luminosity uncertainty not included in the total error.

Table 3

Reduced cross section as measured in the SVX data sample for Q**2 = 0.35 GeV**2. Additional 3 PCT luminosity uncertainty not included in the total error.

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Photoproduction of pi^0 eta on protons and the Delta(1700)D_{33} resonance

The Crystal Ball at MAMI & TAPS & A2 collaborations Kashevarov, V.L. ; Fix, A. ; Aguar-Bartolome, P. ; et al.
Eur.Phys.J.A 42 (2009) 141-149, 2009.
Inspire Record 811783 DOI 10.17182/hepdata.52974

Total and differential cross sections for the reaction gamma p -> pi^o eta p have been measured with the Crystal Ball/TAPS detector using the tagged photon facility at the MAMI C accelerator in Mainz. In the energy range E_gamma=0.95-1.4 GeV the reaction is dominated by the excitation and sequential decay of the Delta(1700)D33 resonance. Angular distributions measured with high statistics allow us to determine the ratio of hadronic decay widths \Gamma_{\eta \Delta}/\Gamma_{\pi S11} and the ratio of the helicity amplitudes A_{3/2}/A_{1/2} for this resonance.

5 data tables
Table 1

Total cross section for the GAMMA P --> PI0 ETA P reaction.. Statistical erros only.

Table 2

The differential cross section as a function of cos(theta(pi0) in the canonical(K) reference frame.. Statistical erros only.

Table 3

The differential cross section as a function of phi(pi0) in the canonical(K) reference frame.. Statistical erros only.

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Cross-sections of large-angle hadron production in proton- and pion-nucleus interactions IV: Copper nuclei and beam momenta from +/-3 GeV/c to +/-15 GeV/c

The HARP-CDP collaboration Bolshakova, A. ; Boyko, I. ; Chelkov, G. ; et al.
Eur.Phys.J.C 64 (2009) 181-241, 2009.
Inspire Record 823636 DOI 10.17182/hepdata.52601

We report on double-differential inclusive cross-sections of the production of secondary protons, charged pions, and deuterons, in the interactions with a 5% nuclear interaction length thick stationary copper target, of proton and pion beams with momentum from +/-3 GeV/c to +/-15 GeV/c. Results are given for secondary particles with production angles between 20 and 125 degrees.

365 data tables
Table 1

Measured cross section as a function of PT for P production from a P beam of momentum 3 GeV/c in the angular range 20 to 30 DEG.

Table 2

Measured cross section as a function of PT for P production from a P beam of momentum 3 GeV/c in the angular range 30 to 40 DEG.

Table 3

Measured cross section as a function of PT for P production from a P beam of momentum 3 GeV/c in the angular range 40 to 50 DEG.

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Angular distributions of leptons from J/psi's produced in 920- GeV fixed-target proton-nucleus collisions

The HERA-B collaboration Abt, I. ; Adams, M. ; Agari, M. ; et al.
Eur.Phys.J.C 60 (2009) 517-524, 2009.
Inspire Record 810555 DOI 10.17182/hepdata.57473

A study of the angular distributions of leptons from decays of J/psi's produced in p-C and p-W collisions at sqrt{s}=41.6 GeV has been performed in the Feynman-x region -0.34 < x_F < 0.14 and for transverse momentum up to 5.4 GeV/c. The data were collected by the HERA-B experiment at the HERA proton ring of the DESY laboratory. The results, based on a clean selection of 2.3 x 10^5 J/psi's reconstructed in both the e^+ e^- and mu^+ mu^- decay channels, indicate that J/psi's are produced with longitudinal polarization. The magnitude of the effect is maximal at low p_T. For p_T >1 GeV/c a significant dependence on the reference frame is found: the polar anisotropy is more pronounced in the Collins-Soper frame and almost vanishes in the helicity frame, where, instead, a significant azimuthal anisotropy arises.

9 data tables
Table 1

Output parameters obtained by fitting the distributions.

Table 2

Values of the parameters Lambda_theta, Lambda_phi et Lambda_theta_phi measured in the Collins-Soper frame as functions of the average reconstructed p_T for combined carbon and tungsten data.

Table 3

Values of the parameters Lambda_theta, Lambda_phi et Lambda_theta_phi measured in the Collins-Soper frame as functions of the average reconstructed x_F for combined carbon and tungsten data.

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