Measurement of Top Quark Polarisation in T-Channel Single Top Quark Production

The CMS collaboration Khachatryan, Vardan ; Sirunyan, Albert M ; Tumasyan, Armen ; et al.
JHEP 04 (2016) 073, 2016.
Inspire Record 1403169 DOI 10.17182/hepdata.38092

A first measurement of the top quark spin asymmetry, sensitive to the top quark polarisation, in t-channel single top quark production is presented. It is based on a sample of pp collisions at a centre-of-mass energy of 8 TeV corresponding to an integrated luminosity of 19.7 inverse-femtobarns. A high-purity sample of t-channel single top quark events with an isolated muon is selected. Signal and background components are estimated using a fit to data. A differential cross section measurement, corrected for detector effects, of an angular observable sensitive to the top quark polarisation is performed. The differential distribution is used to extract a top quark spin asymmetry of 0.26 +/- 0.03 (stat) +/- 0.10 (syst), which is compatible with a p-value of 4.6% with the standard model prediction of 0.44.

0 data tables match query

Measurements of $\pi^\pm$, $K^\pm$, $K^0_S$, $\Lambda$ and proton production in proton-carbon interactions at 31 GeV/$c$ with the NA61/SHINE spectrometer at the CERN SPS

The NA61/SHINE collaboration Abgrall, N. ; Aduszkiewicz, A. ; Ali, Y. ; et al.
Eur.Phys.J.C 76 (2016) 84, 2016.
Inspire Record 1397003 DOI 10.17182/hepdata.19125

Measurements of hadron production in p+C interactions at 31 GeV/c are performed using the NA61/ SHINE spectrometer at the CERN SPS. The analysis is based on the full set of data collected in 2009 using a graphite target with a thickness of 4% of a nuclear interaction length. Inelastic and production cross sections as well as spectra of $\pi^\pm$, $K^\pm$, p, $K^0_S$ and $\Lambda$ are measured with high precision. These measurements are essential for improved calculations of the initial neutrino fluxes in the T2K long-baseline neutrino oscillation experiment in Japan. A comparison of the NA61/SHINE measurements with predictions of several hadroproduction models is presented.

1 data table match query

The double differential $\pi^-$ production cross section in the laboratory system for p+C interactions at 31 GeV$/c$. The results are presented as a function of momentum, $p$ (in [GeV/$c$]), in different angular intervals, $\theta$ (in [mrad]). The statistical and systematic errors are quoted.


$\pi^{-}$C collisions with backward proton emission at 4 and 40 GeV/c

Angelov, N. ; Lutpullaev, S.L. ; Nikitina, V.F. ; et al.
Sov.J.Nucl.Phys. 33 (1981) 98-99, 1981.
Inspire Record 1392857 DOI 10.17182/hepdata.17814

None

0 data tables match query

Study of $\pi^0$ pair production in single-tag two-photon collisions

The Belle collaboration Masuda, M. ; Uehara, S. ; Watanabe, Y. ; et al.
Phys.Rev.D 93 (2016) 032003, 2016.
Inspire Record 1390112 DOI 10.17182/hepdata.71443

We report a measurement of the differential cross section of $\pi^0$ pair production in single-tag two-photon collisions, $\gamma^* \gamma \to \pi^0 \pi^0$, in $e^+ e^-$ scattering. The cross section is measured for $Q^2$ up to 30 GeV$^2$, where $Q^2$ is the negative of the invariant mass squared of the tagged photon, in the kinematic range 0.5 GeV < W < 2.1 GeV and $|\cos \theta^*|$ < 1.0 for the total energy and pion scattering angle, respectively, in the $\gamma^* \gamma$ center-of-mass system. The results are based on a data sample of 759 fb$^{-1}$ collected with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. The transition form factor of the $f_0(980)$ and that of the $f_2(1270)$ with the helicity-0, -1, and -2 components separately are measured for the first time and are compared with theoretical calculations.

0 data tables match query

Angular coefficients of Z bosons produced in pp collisions at $\sqrt{s}$ = 8 TeV and decaying to $\mu^+ \mu^-$ as a function of transverse momentum and rapidity

The CMS collaboration Khachatryan, Vardan ; Sirunyan, Albert M ; Tumasyan, Armen ; et al.
Phys.Lett.B 750 (2015) 154-175, 2015.
Inspire Record 1359451 DOI 10.17182/hepdata.69285

Measurements of the five most significant angular coefficients, A[0] through A[4], for Z bosons produced in pp collisions at $\sqrt{s}$ = 8 TeV and decaying to $\mu^+ \mu^-$ are presented as a function of the transverse momentum and rapidity of Z boson. The integrated luminosity of the dataset collected with the CMS detector at the LHC corresponds to 19.7 inverse femtobarns. These measurements provide comprehensive information about Z boson production mechanisms, and are compared to QCD predictions at leading order, next-to-leading order, and next-to-next-to-leading order in perturbation theory.

0 data tables match query

Distributions of Topological Observables in Inclusive Three- and Four-Jet Events in pp Collisions at sqrt(s) = 7 TeV

The CMS collaboration Khachatryan, Vardan ; Sirunyan, Albert M ; Tumasyan, Armen ; et al.
Eur.Phys.J.C 75 (2015) 302, 2015.
Inspire Record 1345159 DOI 10.17182/hepdata.75115

This paper presents distributions of topological observables in inclusive three- and four-jet events produced in pp collisions at a centre-of-mass energy of 7 TeV with a data sample collected by the CMS experiment corresponding to a luminosity of 5.1 inverse femtobarns. The distributions are corrected for detector effects, and compared with several event generators based on two- and multi-parton matrix elements at leading order. Among the considered calculations, MADGRAPH interfaced with PYTHIA6 displays the best overall agreement with data.

0 data tables match query

Photoproduction of $\omega$ mesons off protons and neutrons

The CBELSA/TAPS collaboration Dietz, F. ; Metag, V. ; Anisovich, A.V. ; et al.
Eur.Phys.J.A 51 (2015) 6, 2015.
Inspire Record 1340913 DOI 10.17182/hepdata.69767

ω photoproduction off hydrogen and deuterium has been studied with the tagged photon beam of the ELSA accelerator in Bonn for photon energies up to 2.0 GeV. The ω meson has been identified via the ω → π$^{0}$ γ → γγγ decay mode, using the combined setup of the Crystal Barrel/TAPS detector systems. Both inclusive and exclusive analyses have been carried out. Differential and total cross-sections have been derived for ω mesons produced off free protons and off protons and neutrons bound in deuterium. The cross-section for the production off the bound neutron is found to be a factor of ≈ 1.3 larger than the one off the bound proton in the incident beam energy region 1.2 GeV < E$_{γ}$ < 1.6 GeV. For higher incident beam energies this factor goes down to ≈ 1.1 at 2.0 GeV. The cross-sections of this work have been used as normalization for transparency ratio measurements.

1 data table match query

Inclusive differential cross-sections of $\omega$ mesons produced off the free proton versus $\cos(\theta^\omega_{\mathrm{c.m.}})$ and versus the momentum transfer to the nucleon, $t$, for incident photon energy $E_\gamma$ = 1.300-1.350 GeV.


Version 2
Measurements of fiducial and differential cross sections for Higgs boson production in the diphoton decay channel at $\sqrt{s}=8$ TeV with ATLAS

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abdallah, Jalal ; et al.
JHEP 09 (2014) 112, 2014.
Inspire Record 1306615 DOI 10.17182/hepdata.65179

Measurements of fiducial and differential cross sections are presented for Higgs boson production in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}=8$ TeV. The analysis is performed in the $H \rightarrow \gamma\gamma$ decay channel using 20.3 fb$^{-1}$ of data recorded by the ATLAS experiment at the CERN Large Hadron Collider. The signal is extracted using a fit to the diphoton invariant mass spectrum assuming that the width of the resonance is much smaller than the experimental resolution. The signal yields are corrected for the effects of detector inefficiency and resolution. The $pp\rightarrow H \rightarrow \gamma\gamma$ fiducial cross section is measured to be $43.2 \pm 9.4 (stat) {}^{+3.2}_{-2.9} (syst) \pm 1.2 (lumi)$ fb for a Higgs boson of mass 125.4 GeV decaying to two isolated photons that have transverse momentum greater than 35% and 25% of the diphoton invariant mass and each with absolute pseudorapidity less than 2.37. Four additional fiducial cross sections and two cross-section limits are presented in phase space regions that test the theoretical modelling of different Higgs boson production mechanisms, or are sensitive to physics beyond the Standard Model. Differential cross sections are also presented, as a function of variables related to the diphoton kinematics and the jet activity produced in the Higgs boson events. The observed spectra are statistically limited but broadly in line with the theoretical expectations.

2 data tables match query

Measured differential cross section with associated uncertainties as a function of cosine of the decay angle in the Collins-Soper frame in bins of diphoton transverse momentum. Each systematic uncertainty sources is fully uncorrelated with the other sources and fully correlated across bins, except for the background modelling systematics for which an uncorrelated treatment across bins is more appropriate.

Measured differential cross section with associated uncertainties as a function of cosine of the decay angle in the Collins-Soper frame in bins of diphoton transverse momentum. Each systematic uncertainty sources is fully uncorrelated with the other sources and fully correlated across bins, except for the background modelling systematics for which an uncorrelated treatment across bins is more appropriate.


Measurement of differential cross sections for the production of a pair of isolated photons in pp collisions at sqrt(s) = 7 TeV

The CMS collaboration Chatrchyan, Serguei ; Khachatryan, Vardan ; Sirunyan, Albert M ; et al.
Eur.Phys.J.C 74 (2014) 3129, 2014.
Inspire Record 1298393 DOI 10.17182/hepdata.64241

A measurement of differential cross sections for the production of a pair of isolated photons in proton-proton collisions at sqrt(s) = 7 TeV is presented. The data sample corresponds to an integrated luminosity of 5.0 inverse femtobarns collected with the CMS detector. A data-driven isolation template method is used to extract the prompt diphoton yield. The measured cross section for two isolated photons, with transverse energy above 40 and 25 GeV respectively, in the pseudorapidity range abs(eta) < 2.5, abs(eta) not in [1.44,1.57] and with an angular separation Delta R > 0.45, is 17.2 +/- 0.2 (stat.) +/- 1.9 (syst.) +/- 0.4 (lum.) pb. Differential cross sections are measured as a function of the diphoton invariant mass, the diphoton transverse momentum, the azimuthal angle difference between the two photons, and the cosine of the polar angle in the Collins-Soper reference frame of the diphoton system. The results are compared to theoretical predictions at leading, next-to-leading, and next-to-next-to-leading order in quantum chromodynamics.

0 data tables match query

High-statistics study of $K^0_S$ pair production in two-photon collisions

The Belle collaboration Uehara, S. ; Watanabe, Y. ; Nakazawa, H. ; et al.
PTEP 2013 (2013) 123C01, 2013.
Inspire Record 1245023 DOI 10.17182/hepdata.62221

We report a high-statistics measurement of the differential cross section of the process gamma gamma --> K^0_S K^0_S in the range 1.05 GeV <= W <= 4.00 GeV, where W is the center-of-mass energy of the colliding photons, using 972 fb^{-1} of data collected with the Belle detector at the KEKB asymmetric-energy e^+ e^- collider operated at and near the Upsilon-resonance region. The differential cross section is fitted by parameterized S-, D_0-, D_2-, G_0- and G_2-wave amplitudes. In the D_2 wave, the f_2(1270), a_2(1320) and f_2'(1525) are dominant and a resonance, the f_2(2200), is also present. The f_0(1710) and possibly the f_0(2500) are seen in the S wave. The mass, total width and product of the two-photon partial decay width and decay branching fraction to the K bar{K} state Gamma_{gamma gamma}B(K bar{K}) are extracted for the f_2'(1525), f_0(1710), f_2(2200) and f_0(2500). The destructive interference between the f_2(1270) and a_2(1320) is confirmed by measuring their relative phase. The parameters of the charmonium states chi_{c0} and chi_{c2} are updated. Possible contributions from the chi_{c0}(2P) and chi_{c2}(2P) states are discussed. A new upper limit for the branching fraction of the P- and CP-violating decay channel eta_c --> K^0_S K^0_S is reported. The detailed behavior of the cross section is updated and compared with QCD-based calculations.

1 data table match query

The cos(Theta*) dependence of the differential cross section for the W ranges 1.70-1.71, 1.71-1.72 and 1.72-1.73.


Measurement of the Differential Cross Section $d{\sigma}/d(\cos {\theta}t)$ for Top-Quark Pair Production in $p-\bar{p}$ Collisions at $\sqrt{s} = 1.96$ TeV

The CDF collaboration Aaltonen, T. ; Amerio, S. ; Amidei, D. ; et al.
Phys.Rev.Lett. 111 (2013) 182002, 2013.
Inspire Record 1238100 DOI 10.17182/hepdata.64392

We report a measurement of the differential cross section, d{\sigma}/d(cos {\theta}t), for top-quark-pair production as a function of the top-quark production angle in proton-antiproton collisions at sqrt{s} = 1.96 TeV. This measurement is performed using data collected with the CDF II detector at the Tevatron, corresponding to an integrated luminosity of 9.4/fb. We employ the Legendre polynomials to characterize the shape of the differential cross section at the parton level. The observed Legendre coefficients are in good agreement with the prediction of the next-to-leading-order standard-model calculation, with the exception of an excess linear-term coefficient, a1 = 0.40 +- 0.12, compared to the standard-model prediction of a1 = 0.15^{+0.07}_{-0.03}.

0 data tables match query

Measurement of the differential cross sections for isolated direct photon pair production in $p \bar p$ collisions at $\sqrt{s} = 1.96$ TeV

The D0 collaboration Abazov, V.M. ; Abbott, Braden Keim ; Acharya, Bannanje Sripath ; et al.
Phys.Lett.B 725 (2013) 6-14, 2013.
Inspire Record 1215307 DOI 10.17182/hepdata.60556

We present measurements of direct photon pair production cross sections using 8.5 fb$^{-1}$ of data collected with the D0 detector at the Fermilab Tevatron $p \bar p$ collider. The results are presented as differential distributions of the photon pair invariant mass $d\sigma/dM_{\gamma \gamma}$, pair transverse momentum $d \sigma /dp^{\gamma \gamma}_T$, azimuthal angle between the photons $d\sigma/d\Delta \phi_{\gamma \gamma}$, and polar scattering angle in the Collins-Soper frame $d\sigma /d|\cos \theta^*|$. Measurements are performed for isolated photons with transverse momenta $p^{\gamma}_T>18 ~(17)$ GeV for the leading (next-to-leading) photon in $p_T$, pseudorapidities $|\eta^{\gamma}|<0.9$, and a separation in $\eta-\phi$ space $\Delta\mathcal R_{\gamma\gamma} > 0.4$. We present comparisons with the predictions from Monte Carlo event generators {\sc diphox} and {\sc resbos} implementing QCD calculations at next-to-leading order, $2\gamma${\sc nnlo} at next-to-next-to-leading order, and {\sc sherpa} using matrix elements with higher-order real emissions matched to parton shower.

0 data tables match query

Measurement of isolated-photon pair production in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abajyan, Tatevik ; Abbott, Brad ; et al.
JHEP 01 (2013) 086, 2013.
Inspire Record 1199269 DOI 10.17182/hepdata.62320

The ATLAS experiment at the LHC has measured the production cross section of events with two isolated photons in the final state, in proton-proton collisions at sqrt(s) = 7 TeV. The full data set collected in 2011, corresponding to an integrated luminosity of 4.9 fb-1, is used. The amount of background, from hadronic jets and isolated electrons, is estimated with data-driven techniques and subtracted. The total cross section, for two isolated photons with transverse energies above 25 GeV and 22 GeV respectively, in the acceptance of the electromagnetic calorimeter (|eta|<1.37 and 1.52<|eta|<2.37) and with an angular separation Delta R>0.4, is 44.0 (+3.2) (-4.2) pb. The differential cross sections as a function of the di-photon invariant mass, transverse momentum, azimuthal separation, and cosine of the polar angle of the largest transverse energy photon in the Collins--Soper di-photon rest frame are also measured. The results are compared to the prediction of leading-order parton-shower and next-to-leading-order and next-to-next-to-leading-order parton-level generators.

0 data tables match query

Measurement of the Production Cross Section for Pairs of Isolated Photons in pp collisions at sqrt(s) = 7 TeV

The CMS collaboration Chatrchyan, Serguei ; Khachatryan, Vardan ; Sirunyan, Albert M ; et al.
JHEP 01 (2012) 133, 2012.
Inspire Record 943720 DOI 10.17182/hepdata.58959

The integrated and differential cross sections for the production of pairs of isolated photons is measured in proton-proton collisions at a centre-of-mass energy of 7 TeV with the CMS detector at the LHC. A data sample corresponding to an integrated luminosity of 36 inverse picobarns is analysed. A next-to-leading-order perturbative QCD calculation is compared to the measurements. A discrepancy is observed for regions of the phase space where the two photons have an azimuthal angle difference, $\Delta(\phi)$, less than approximately 2.8.

0 data tables match query

Measurement of the Cross Section for Prompt Isolated Diphoton Production in p\bar p Collisions at \sqrt{s} = 1.96 TeV

The CDF collaboration Aaltonen, T. ; Alvarez Gonzalez, B. ; Amerio, S. ; et al.
Phys.Rev.D 84 (2011) 052006, 2011.
Inspire Record 915978 DOI 10.17182/hepdata.60557

This article reports a measurement of the production cross section of prompt isolated photon pairs in proton-antiproton collisions at \sqrt{s} = 1.96 TeV using the CDF II detector at the Fermilab Tevatron collider. The data correspond to an integrated luminosity of 5.36/fb. The cross section is presented as a function of kinematic variables sensitive to the reaction mechanisms. The results are compared with three perturbative QCD calculations: (1) a leading order parton shower Monte Carlo, (2) a fixed next-to-leading order calculation and (3) a next-to-leading order/next-to-next-to-leading-log resummed calculation. The comparisons show that, within their known limitations, all calculations predict the main features of the data, but no calculation adequately describes all aspects of the data.

0 data tables match query

Delta Delta Excitation in Proton-Proton Induced pi0pi0 Production

Skorodko, T. ; Bashkanov, M. ; Bogoslawsky, D. ; et al.
Phys.Lett.B 695 (2011) 115-123, 2011.
Inspire Record 860341 DOI 10.17182/hepdata.56497

Exclusive measurements of the $pp \to pp\pi^0\pi^0$ reaction have been performed at CELSIUS/WASA at energies from threshold up to $T_p$ = 1.3 GeV. Total and differential cross sections have been obtained. Here we concentrate on energies $T_p \ge$ 1 GeV, where the $\Delta\Delta$ excitation becomes the leading process. No evidence is found for a significant ABC effect beyond that given by the conventional $t$-channel $\Delta\Delta$ excitation. This holds also for the double-pionic fusion to the quasibound $^2$He. The data are compared to model predictions, which are based on both pion and $\rho$ exchange. Total and differential cross sections are at variance with these predictions and call for a profound modification of the $\rho$-exchange. A phenomenological modification allowing only a small $\rho$ exchange contribution leads to a quantitative description of the data.

1 data table match query

Distribution of the cosine of the PI0 centre-of-mass angle at an incident kinetic energy of 1000 MeV.


Measurement of eta eta production in two-photon collisions

The Belle collaboration Uehara, S. ; Watanabe, Y. ; Nakazawa, H. ; et al.
Phys.Rev.D 82 (2010) 114031, 2010.
Inspire Record 862260 DOI 10.17182/hepdata.56262

We report the first measurement of the differential cross section for the process gamma gamma --> eta eta in the kinematic range above the eta eta threshold, 1.096 GeV < W < 3.8 GeV over nearly the entire solid angle range, |cos theta*| <= 0.9 or <= 1.0 depending on W, where W and theta* are the energy and eta scattering angle, respectively, in the gamma gamma center-of-mass system. The results are based on a 393 fb^{-1} data sample collected with the Belle detector at the KEKB e^+ e^- collider. In the W range 1.1-2.0 GeV/c^2 we perform an analysis of resonance amplitudes for various partial waves, and at higher energy we compare the energy and the angular dependences of the cross section with predictions of theoretical models and extract contributions of the chi_{cJ} charmonia.

1 data table match query

Angular dependence of the differential cross section for the W range 1.880 to 1.920 GeV.


Differential cross sections and recoil polarizations for the reaction gamma p -> K+ Sigma0

The CLAS collaboration Dey, B. ; Meyer, C.A. ; Bellis, M. ; et al.
Phys.Rev.C 82 (2010) 025202, 2010.
Inspire Record 857728 DOI 10.17182/hepdata.55696

High-statistics measurements of differential cross sections and recoil polarizations for the reaction $\gamma p \rightarrow K^+ \Sigma^0$ have been obtained using the CLAS detector at Jefferson Lab. We cover center-of-mass energies ($\sqrt{s}$) from 1.69 to 2.84 GeV, with an extensive coverage in the $K^+$ production angle. Independent measurements were made using the $K^{+}p\pi^{-}$($\gamma$) and $K^{+}p$($\pi^-, \gamma$) final-state topologies, and were found to exhibit good agreement. Our differential cross sections show good agreement with earlier CLAS, SAPHIR and LEPS results, while offering better statistical precision and a 300-MeV increase in $\sqrt{s}$ coverage. Above $\sqrt{s} \approx 2.5$ GeV, $t$- and $u$-channel Regge scaling behavior can be seen at forward- and backward-angles, respectively. Our recoil polarization ($P_\Sigma$) measurements represent a substantial increase in kinematic coverage and enhanced precision over previous world data. At forward angles we find that $P_\Sigma$ is of the same magnitude but opposite sign as $P_\Lambda$, in agreement with the static SU(6) quark model prediction of $P_\Sigma \approx -P_\Lambda$. This expectation is violated in some mid- and backward-angle kinematic regimes, where $P_\Sigma$ and $P_\Lambda$ are of similar magnitudes but also have the same signs. In conjunction with several other meson photoproduction results recently published by CLAS, the present data will help constrain the partial wave analyses being performed to search for missing baryon resonances.

1 data table match query

Differential cross section as a function of COS(THETA(K+,CM)) for the centre-of mass range 1.9 to 1.91 GeV.


Differential cross section of gamma n to K+ Sigma- on bound neutrons with incident photons from 1.1 to 3.6 GeV

The CLAS collaboration Pereira, S.Anefalos ; Mirazita, M. ; Rossi, P. ; et al.
Phys.Lett.B 688 (2010) 289-293, 2010.
Inspire Record 841145 DOI 10.17182/hepdata.38239

Differential cross sections of the reaction gamma d to K+ Sigma- (p) have been measured with the CLAS detector at Jefferson Lab using incident photons with energies between 1.1 and 3.6 GeV. This is the first complete set of strangeness photoproduction data on the neutron covering a broad angular range. At energies close to threshold and up to E_gamma ~ 1.8 GeV, the shape of the angular distribution is suggestive of the presence of s-channel production mechanisms. For E_gamma > 1.8 GeV, a clear forward peak appears and becomes more prominent as the photon energy increases, suggesting contributions from t-channel production mechanisms. These data can be used to constrain future analysis of this reaction.

1 data table match query

Differential cross section for the reaction GAMMA DEUT --> K+ SIGMA-(P) at incident photon energy 3.25 GeV.. Errors contain both statistics and systematics.


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.

1 data table match query

Differential cross section as a function of COS(THETA(K)) for the centre-of-mass range 1.83-1.84 GeV.


Comparison of large-angle production of charged pions with incident protons on cylindrical long and short targets

The HARP collaboration Apollonio, M. ; Artamonov, A. ; Bagulya, A. ; et al.
Phys.Rev.C 80 (2009) 065204, 2009.
Inspire Record 830148 DOI 10.17182/hepdata.54193

The HARP collaboration has presented measurements of the double-differential pi+/pi- production cross-section in the range of momentum 100 MeV/c <= p 800 MeV/c and angle 0.35 rad <= theta <= 2.15 rad with proton beams hitting thin nuclear targets. In many applications the extrapolation to long targets is necessary. In this paper the analysis of data taken with long (one interaction length) solid cylindrical targets made of carbon, tantalum and lead is presented. The data were taken with the large acceptance HARP detector in the T9 beam line of the CERN PS. The secondary pions were produced by beams of protons with momenta 5 GeV/c, 8 GeV/c and 12 GeV/c. The tracking and identification of the produced particles were performed using a small-radius cylindrical time projection chamber (TPC) placed inside a solenoidal magnet. Incident protons were identified by an elaborate system of beam detectors. Results are obtained for the double-differential yields per target nucleon d2 sigma / dp dtheta. The measurements are compared with predictions of the MARS and GEANT4 Monte Carlo simulations.

1 data table match query

Differential cross section for PI+ production with a TA target in the angular range 0.95 to 1.15 radians.. The errors are the square root of the diagonal elements of the covariant matrix.


Differential cross sections and spin density matrix elements for the reaction $\gamma p \to p \omega$

The CLAS collaboration Williams, M. ; Applegate, D. ; Bellis, M. ; et al.
Phys.Rev.C 80 (2009) 065208, 2009.
Inspire Record 829180 DOI 10.17182/hepdata.52667

High-statistics differential cross sections and spin density matrix elements for the reaction $\gamma p \to p \omega$ have been measured using the CLAS at Jefferson Lab for center-of-mass (CM) energies from threshold up to 2.84 GeV. Results are reported in 112 10-MeV wide CM energy bins, each subdivided into $\cos{\theta_{CM}^{\omega}}$ bins of width 0.1. These are the most precise and extensive $\omega$ photoproduction measurements to date. A number of prominent structures are clearly present in the data. Many of these have not previously been observed due to limited statistics in earlier measurements.

1 data table match query

Differential cross section for the W range 1.93 to 1.94 GeV.


Large-angle production of charged pions with incident pion beams on nuclear targets

The HARP collaboration Apollonio, M. ; Artamonov, A. ; Bagulya, A. ; et al.
Phys.Rev.C 80 (2009) 065207, 2009.
Inspire Record 825244 DOI 10.17182/hepdata.50467

Measurements of the double-differential pi+/- production cross-section in the range of momentum 100 MeV/c <= p <= 800 MeV/c and angle 0.35 rad <= theta <= 2.15 rad using pi+/- beams incident on beryllium, aluminium, carbon, copper, tin, tantalum and lead targets are presented. The data were taken with the large acceptance HARP detector in the T9 beam line of the CERN PS. The secondary pions were produced by beams in a momentum range from 3 GeV/c to 12.9 GeV/c hitting a solid target with a thickness of 5% of a nuclear interaction length. The tracking and identification of the produced particles was performed using a small-radius cylindrical time projection chamber (TPC) placed inside a solenoidal magnet. Incident particles were identified by an elaborate system of beam detectors. Results are obtained for the double-differential cross-sections d2sigma/dpdtheta at six incident beam momenta. Data at 3 GeV/c, 5 GeV/c, 8 GeV/c, and 12 GeV/c are available for all targets while additional data at 8.9 GeV/c and 12.9 GeV/c were taken in positive particle beams on Be and Al targets, respectively. The measurements are compared with several generators of GEANT4 and the MARS Monte Carlo simulation.

1 data table match query

No description provided.


High-statistics study of neutral-pion pair production in two-photon collisions

The Belle collaboration Uehara, S. ; Watanabe, Y. ; Nakazawa, H. ; et al.
Phys.Rev.D 79 (2009) 052009, 2009.
Inspire Record 815978 DOI 10.17182/hepdata.52161

The differential cross sections for the process $\gamma \gamma \to \pi^0 \pi^0$ have been measured in the kinematic range 0.6 GeV $< W < 4.1$ GeV, $|\cos \theta^*|<0.8$ in energy and pion scattering angle, respectively, in the $\gamma\gamma$ center-of-mass system. The results are based on a 223 fb$^{-1}$ data sample collected with the Belle detector at the KEKB $e^+ e^-$ collider. The differential cross sections are fitted in the energy region 1.7 GeV $< W <$ 2.5 GeV to confirm the two-photon production of two pions in the G wave. In the higher energy region, we observe production of the $\chi_{c0}$ charmonium state and obtain the product of its two-photon decay width and branching fraction to $\pi^0\pi^0$. We also compare the observed angular dependence and ratios of cross sections for neutral-pion and charged-pion pair production to QCD models. The energy and angular dependence above 3.1 GeV are compatible with those measured in the $\pi^+\pi^-$ channel, and in addition we find that the cross section ratio, $\sigma(\pi^0\pi^0)/\sigma(\pi^+\pi^-)$, is $0.32 \pm 0.03 \pm 0.05$ on average in the 3.1-4.1 GeV region.

1 data table match query

Differential cross section for W = 1.94, 1.98 and 2.02 GeV.


Angular correlations in three-jet events in ep collisions at HERA

The ZEUS collaboration Chekanov, S. ; Derrick, M. ; Magill, S. ; et al.
Phys.Rev.D 85 (2012) 052008, 2012.
Inspire Record 793931 DOI 10.17182/hepdata.45283

Three-jet production in deep inelastic ep scattering and photoproduction was investigated with the ZEUS detector at HERA using an integrated luminosity of 127 pb-1. Measurements of differential cross sections are presented as functions of angular correlations between the three jets in the final state and the proton-beam direction. These correlations provide a stringent test of perturbative QCD and show sensitivity to the contributions from different colour configurations. Fixed-order perturbative QCD calculations assuming the values of the colour factors C_F, C_A and T_F as derived from a variety of gauge groups were compared to the measurements to study the underlying gauge group symmetry. The measured angular correlations in the deep inelastic ep scattering and photoproduction regimes are consistent with the admixture of colour configurations as predicted by SU(3) and disfavour other symmetry groups, such as SU(N) in the limit of large N.

0 data tables match query

High-statistics measurement of neutral pion-pair production in two-photon collisions

The Belle collaboration Uehara, S. ; Watanabe, Y. ; Adachi, I. ; et al.
Phys.Rev.D 78 (2008) 052004, 2008.
Inspire Record 786406 DOI 10.17182/hepdata.50151

We report a high-statistics measurement of differential cross sections for the process gamma gamma -> pi^0 pi^0 in the kinematic range 0.6 GeV <= W <= 4.0 GeV and |cos theta*| <= 0.8, where W and theta* are the energy and pion scattering angle, respectively, in the gamma gamma center-of-mass system. Differential cross sections are fitted to obtain information on S, D_0, D_2, G_0 and G_2 waves. The G waves are important above W ~= 1.6 GeV. For W <= 1.6 GeV the D_2 wave is dominated by the f_2(1270) resonance while the S wave requires at least one additional resonance besides the f_0(980), which may be the f_0(1370) or f_0(1500). The differential cross sections are fitted with a simple parameterization to determine the parameters (the mass, total width and Gamma_{gamma gamma}B(f_0 -> pi^0 pi^0)) of this scalar meson as well as the f_0(980). The helicity 0 fraction of the f_2(1270) meson, taking into account interference for the first time, is also obtained.

1 data table match query

Differential cross section for W = 2.14, 2.18 and 2.22 GeV.


Large-angle production of charged pions with 3-12.9 GeV/c incident protons on nuclear targets

The HARP collaboration Catanesi, M.G. ; Radicioni, E. ; Edgecock, R. ; et al.
Phys.Rev.C 77 (2008) 055207, 2008.
Inspire Record 786183 DOI 10.17182/hepdata.13425

Measurements of the double-differential charged pion production cross-section in the range of momentum 100 MeV/c &lt; p &lt; 800 MeV/c and angle 0.35 &lt; \theta &lt; 2.15 rad in proton-beryllium, proton-carbon, proton-aluminium, proton-copper, proton-tin, proton-tantalum and proton-lead collisions are presented. The data were taken with the large acceptance HARP detector in the T9 beam line of the CERN PS. The pions were produced by proton beams in a momentum range from 3 GeV/c to 12.9 GeV/c hitting a target with a thickness of 5% of a nuclear interaction length.

1 data table match query

Double-differential cross section for inclusive PI+ production in the LAB system with the C target for a PI+ polar angle from 0.95 to 1.15 radians.


Three- and Four-jet Production at Low x at HERA

The H1 collaboration Aaron, F.D. ; Aktas, A. ; Alexa, C. ; et al.
Eur.Phys.J.C 54 (2008) 389-409, 2008.
Inspire Record 767896 DOI 10.17182/hepdata.45429

Three- and four-jet production is measured in deep-inelastic $ep$ scattering at low $x$ and $Q^2$ with the H1 detector using an integrated luminosity of $44{.}2 {\rm pb}^{-1}$. Several phase space regions are selected for the three-jet analysis in order to study the underlying parton dynamics from global topologies to the more restrictive regions of forward jets close to the proton direction. The measurements of cross sections for events with at least three jets are compared to fixed order QCD predictions of ${\mathcal{O}}(\alpha_{\rm s}^2)$ and ${\mathcal{O}}(\alpha_{\rm s}^3) $ and with Monte Carlo simulation programs where higher order effects are approximated by parton showers. A good overall description is provided by the ${\mathcal{O}}(\alpha_{\rm s}^3) $ calculation. Too few events are predicted at the lowest $x \sim 10^{-4}$, especially for topologies with two forward jets. This hints to large contributions at low $x$ from initial state radiation of gluons close to the proton direction and unordered in transverse momentum. The Monte Carlo program in which gluon radiation is generated by the colour dipole model gives a good description of both the three- and the four-jet data in absolute normalisation and shape.

1 data table match query

Differential cross section as a function the jet angle THETA for events with at least 4 jets.


Large-angle production of charged pions by 3 GeV/c - 12 GeV/c protons on carbon, copper and tin targets

The HARP collaboration Catanesi, M.G. ; Edgecock, R. ; Ellis, Malcolm ; et al.
Eur.Phys.J.C 53 (2008) 177-204, 2008.
Inspire Record 761546 DOI 10.17182/hepdata.51401

A measurement of the double-differential $\pi^{\pm}$ production cross-section in proton--carbon, proton--copper and proton--tin collisions in the range of pion momentum $100 \MeVc \leq p &lt; 800 \MeVc$ and angle $0.35 \rad \le \theta &lt;2.15 \rad$ is presented. The data were taken with the HARP detector in the T9 beam line of the CERN PS. The pions were produced by proton beams in a momentum range from 3 \GeVc to 12 \GeVc hitting a target with a thickness of 5% of a nuclear interaction length. The tracking and identification of the produced particles was done using a small-radius cylindrical time projection chamber (TPC) placed in a solenoidal magnet. An elaborate system of detectors in the beam line ensured the identification of the incident particles. Results are shown for the double-differential cross-sections at four incident proton beam momenta (3 \GeVc, 5 \GeVc, 8 \GeVc and 12 \GeVc).

1 data table match query

Double-differential cross section for PI+ production from CU in the LAB system for PI+ polar angle from 0.95 to 1.15 radians.


Large-angle production of charged pions by 3 GeV/c - 12.9 GeV/c protons on beryllium, aluminium and lead targets

The HARP collaboration Catanesi, M.G. ; Radicioni, E. ; Edgecock, R. ; et al.
Eur.Phys.J.C 54 (2008) 37-60, 2008.
Inspire Record 761543 DOI 10.17182/hepdata.51357

Measurements of the double-differential $\pi^{\pm}$ production cross-section in the range of momentum $100 \MeVc \leq p &lt; 800 \MeVc$ and angle $0.35 \rad \leq \theta &lt; 2.15 \rad$ in proton--beryllium, proton--aluminium and proton--lead collisions are presented. The data were taken with the HARP detector in the T9 beam line of the CERN PS. The pions were produced by proton beams in a momentum range from 3 \GeVc to 12.9 \GeVc hitting a target with a thickness of 5% of a nuclear interaction length. The tracking and identification of the produced particles was performed using a small-radius cylindrical time projection chamber (TPC) placed inside a solenoidal magnet. Incident particles were identified by an elaborate system of beam detectors. Results are obtained for the double-differential cross-sections at six incident proton beam momenta (3 \GeVc, 5 \GeVc, 8 \GeVc, 8.9 \GeVc (Be only), 12 \GeVc and 12.9 \GeVc (Al only)) and compared to previously available data.

1 data table match query

Double-differential cross section for PI+ production from AL in the LAB system for PI+ polar angle from 0.95 to 1.15 radians.


Single \pi^- production in np collisions for excess energies up to 90 MeV

The COSY-TOF collaboration Abdel-Bary, M. ; Brinkmann, K. -Th. ; Clement, H. ; et al.
Eur.Phys.J.A 36 (2008) 7-16, 2008.
Inspire Record 759337 DOI 10.17182/hepdata.66229

The quasifree reaction $np\to pp\pim$ was studied in a kinematically complete experiment by bombarding a liquid hydrogen target with a deuteron beam of momentum 1.85 GeV/c and analyzing the data along the lines of the spectator model. In addition to the three charged ejectiles the spectator proton was also detected in the large-acceptance time-of-flight spectrometer COSY-TOF. It was identified by its momentum and flight direction thus yielding access to the Fermi motion of the bound neutron and to the effective neutron 4-momentum vector $\mathbb{P}_n$ which differed from event to event. A range of almost 90 MeV excess energy above threshold was covered. Energy dependent angular distributions, invariant mass spectra as well as fully covered Dalitz plots were deduced. Sizeable $pp$ FSI effects were found as were contributions of $p$ and $d$ partial waves. The behavior of the elementary cross section $\sigma_{01}$ close to threshold is discussed in view of new cross section data. In comparison with existing literature data the results provide a sensitive test of the spectator model.

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Measurement of the production of charged pions by protons on a tantalum target

The HARP collaboration Catanesi, M.G. ; Radicioni, E. ; Edgecock, R. ; et al.
Eur.Phys.J.C 51 (2007) 787-824, 2007.
Inspire Record 752890 DOI 10.17182/hepdata.51527

A measurement of the double-differential cross-section for the production of charged pions in proton--tantalum collisions emitted at large angles from the incoming beam direction is presented. The data were taken in 2002 with the HARP detector in the T9 beam line of the CERN PS. The pions were produced by proton beams in a momentum range from 3 \GeVc to 12 \GeVc hitting a tantalum target with a thickness of 5% of a nuclear interaction length. The angular and momentum range covered by the experiment ($100 \MeVc \le p &lt; 800 \MeVc$ and $0.35 \rad \le \theta &lt;2.15 \rad$) is of particular importance for the design of a neutrino factory. The produced particles were detected using a small-radius cylindrical time projection chamber (TPC) placed in a solenoidal magnet. Track recognition, momentum determination and particle identification were all performed based on the measurements made with the TPC. An elaborate system of detectors in the beam line ensured the identification of the incident particles. Results are shown for the double-differential cross-sections ${{\mathrm{d}^2 \sigma}} / {{\mathrm{d}p\mathrm{d}\theta}}$ at four incident proton beam momenta (3 \GeVc, 5 \GeVc, 8 \GeVc and 12 \GeVc). In addition, the pion yields within the acceptance of typical neutrino factory designs are shown as a function of beam momentum. The measurement of these yields within a single experiment eliminates most systematic errors in the comparison between rates at different beam momenta and between positive and negative pion production.

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High statistics measurement of the cross sections of gamma gamma --> pi+ pi- production.

The Belle collaboration Mori, T. ; Uehara, S. ; Watanabe, Y. ; et al.
J.Phys.Soc.Jap. 76 (2007) 074102, 2007.
Inspire Record 749358 DOI 10.17182/hepdata.51842

We report on a high statistics measurement of the total and differential cross sections of the process gamma gamma -> pi^+ pi^- in the pi^+ pi^- invariant mass range 0.8 GeV/c^2 < W < 1.5 GeV/c^2 with 85.9 fb^{-1} of data collected at sqrt{s}=10.58 GeV and 10.52 GeV with the Belle detector. A clear signal of the f_0(980) resonance is observed in addition to the f_2(1270) resonance. An improved 90% confidence level upper limit Br.(eta'(958) -> pi^+ pi^-) < 2.9 x 10^{-3} is obtained for P- and CP-violating decay of the eta'(958) meson using the most conservative assumption about the interference with the background.

1 data table match query

No description provided.


Cascade production in the reactions gamma p --> K+ K+ (X) and gamma p --> K^+ K^+ pi- (X)

Guo, L. ; Weygand, D.P. ; Battaglieri, M. ; et al.
Phys.Rev.C 76 (2007) 025208, 2007.
Inspire Record 744487 DOI 10.17182/hepdata.31494

Photoproduction of the cascade resonances has been investigated in the reactions $\gamma p \to K^+ K^+ (X)$ and $\gamma p \to K^+ K^+ \pi^- (X)$. The mass split of the $\Xi$ doublet is measured to be $5.4\pm 1.8$ MeV/c$^2$, consistent with existing measurements. The differential (total) cross sections for the $\Xi^{-}$ have been determined for photon beam energies from 2.75 to 3.85 (4.75) GeV, and are consistent with a possible production mechanism of $Y^*\to K^+\Xi^-$ through a $t$-channel process. The reaction $\gamma p \to K^+ K^+ \pi^-[\Xi^0]$ has also been investigated in search of excited cascade resonances. No significant signal of excited cascade states other than the $\Xi^-(1530)$ is observed. The cross section results of the $\Xi^-(1530)$ have also been obtained for photon beam energies from 3.35 to 4.75 GeV.

1 data table match query

Differential cross section for XI- production as a function of the invariant mass of the K+ meson pair for incident photon energy 3.79 Gev.


A study of gamma gamma -> Ks Ks production at energies of 2.4-4.0GeV at Belle

The Belle collaboration Chen, W.T. ; Abe, Kazuo ; Abe, K. ; et al.
Phys.Lett.B 651 (2007) 15-21, 2007.
Inspire Record 726900 DOI 10.17182/hepdata.38419

$K^0_SK^0_S$ production in two-photon collisions has been studied using a 397.6 fb$^{-1}$ data sample collected with the Belle detector at the KEKB $e^+e^-$ collider. For the first time the cross sections are measured in the two-photon center-of-mass energy range between 2.4 GeV and 4.0 GeV and angular range $|\cos\theta^*|<0.6$. Combining the results with measurements of $\gamma\gamma\to K^+K^-$ from Belle, we observe that the cross section ratio $\sigma(K^0_SK^0_S)/\sigma(K^+K^-)$ decreases from ~0.13 to ~0.01 with increasing energy. Signals for the $\chi_{c0}$ and $\chi_{c2}$ charmonium states are also observed.

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Study of the p d --> He-3 K+ K- and p d --> He-3 Phi reactions close to threshold.

The COSY-MOMO collaboration Bellemann, F. ; Berg, A. ; Bisplinghoff, J. ; et al.
Phys.Rev.C 75 (2007) 015204, 2007.
Inspire Record 724774 DOI 10.17182/hepdata.31632

Two--kaon production in proton--deuteron collisions has been studied at three energies close to threshold using a calibrated magnetic spectrograph to measure the final $^3$He and a vertex detector to measure the $K^+K^-$ pair. Differential and total cross sections are presented for the production of $\phi$--mesons, decaying through $\phi\to K^+K^-$, as well as for prompt $K^+K^-$ production. The prompt production seems to follow phase space in both its differential distributions and in its energy dependence. The amplitude for the $pd\to ^3${He}$ \phi$ reaction varies little for excess energies below 22 MeV and the value is consistent with that obtained from a threshold measurement. The angular distribution of the $K^+K^-$ decay pair shows that near threshold the $\phi$--mesons are dominantly produced with polarization $m=0$ along the initial proton direction. No conclusive evidence for $f_0(980)$ production is found in the data.

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Measurement and interpretation of fermion-pair production at LEP energies above the Z resonance.

The DELPHI collaboration Abdallah, J. ; Abreu, P. ; Adam, W. ; et al.
Eur.Phys.J.C 45 (2006) 589-632, 2006.
Inspire Record 699726 DOI 10.17182/hepdata.48590

This paper presents DELPHI measurements and interpretations of cross-sections, forward-backward asymmetries, and angular distributions, for the e+e- -> ffbar process for centre-of-mass energies above the Z resonance, from sqrt(s) ~ 130 - 207 GeV at the LEP collider. The measurements are consistent with the predictions of the Standard Model and are used to study a variety of models including the S-Matrix ansatz for e+e- -> ffbar scattering and several models which include physics beyond the Standard Model: the exchange of Z' bosons, contact interactions between fermions, the exchange of gravitons in large extra dimensions and the exchange of sneutrino in R-parity violating supersymmetry.

1 data table match query

Differential cross sections for non-radiative E+ E- --> TAU+ TAU- events atcentre of mass energy 189 GeV.


Measurement of hadron and lepton-pair production in e+ e- collisions at s**(1/2) = 192-GeV - 208-GeV at LEP.

The L3 collaboration Achard, P. ; Adriani, O. ; Aguilar-Benitez, M. ; et al.
Eur.Phys.J.C 47 (2006) 1-19, 2006.
Inspire Record 704275 DOI 10.17182/hepdata.48637

Hadron production and lepton-pair production in e+e- collisions are studied with data collected with the L3 detector at LEP at centre-of-mass energies sqrt{s}=192-208GeV. Using a total integrated luminosity of 453/pb, 36057 hadronic events and 12863 lepton-pair events are selected. The cross sections for hadron production and lepton-pair production are measured for the full sample and for events where no high-energy initial-state-radiation photon is emitted prior to the collisions. Lepton-pair events are further investigated and forward-backward asymmetries are measured. Finally, the differential cross sections for electron-positron pair-production is determined as a function of the scattering angle. An overall good agreement is found with Standard Model predictions.

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Measurement of pi0 photoproduction on the proton from 550-MeV to 1500-MeV at GRAAL

The GRAAL collaboration Bartalini, O. ; Bellini, V. ; Bocquet, J.P. ; et al.
Eur.Phys.J.A 26 (2005) 399-419, 2005.
Inspire Record 703671 DOI 10.17182/hepdata.11281

Neutral pion photoproduction has been measured from 550 to 1500 MeV with the GRAAL facility, located at the ESRF in Grenoble. Differential cross-section and beam asymmetry have been measured over a wi

1 data table match query

Measured differential angular distribution for incident photon energy 925 Mev.


Measurement of the gamma gamma --> pi+ pi- and gamma gamma --> K+ K- processes at energies of 2.4-GeV - 4.1-GeV.

The Belle collaboration Nakazawa, H. ; Uehara, S. ; Abe, K. ; et al.
Phys.Lett.B 615 (2005) 39-49, 2005.
Inspire Record 667712 DOI 10.17182/hepdata.68395

We have measured pi+pi- and K+K- production in two-photon collisions using 87.7 /fb of data collected with the Belle detector at the asymmetric energy e+e- collider KEKB. The cross sections are measured to high precision in the two-photon center-of-mass energy (W) range between 2.4 GeV < W < 4.1 GeV and angular region |cos theta^{*}| < 0.6. The cross section ratio sigma(gammagamma->K+K-)/sigma(gammagamma->pi+pi-) is measured to be 0.89 +- 0.04(stat) +- 0.15(syst) in the range of 3.0 GeV < W < 4.1 GeV, where the ratio is energy independent. We observe a sin^{-4} theta^{*} behavior of the cross section in the same W range. Production of chi_{c0} and chi_{c2} mesons is observed in both gammagamma -> pi+pi- and gammagamma -> K+K- modes.

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Minijet deformation and charge-independent angular correlations on momentum subspace (eta, phi) in Au-Au collisions at s(NN)**(1/2) = 130-GeV

The STAR collaboration Adams, John ; Aggarwal, M.M. ; Ahammed, Z. ; et al.
Phys.Rev.C 73 (2006) 064907, 2006.
Inspire Record 663650 DOI 10.17182/hepdata.102089

First measurements of charge-independent correlations on angular difference variables $\eta_1 - \eta_2$ (pseudorapidity) and $\phi_1 - \phi_2$ (azimuth) are presented for primary charged hadrons with transverse momentum $0.15 \leq p_t \leq 2$ GeV/$c$ and $|\eta| \leq 1.3$ from Au-Au collisions at $\sqrt{s_{NN}} = 130$ GeV. Strong charge-independent angular correlations are observed associated with jet-like structures and elliptic flow. The width of the jet-like peak on $\eta_1 - \eta_2$ increases by a factor 2.3 from peripheral to central collisions, suggesting strong coupling of semi-hard scattered partons to a longitudinally-expanding medium. New methods of jet analysis introduced here provide evidence for nonperturbative QCD medium effects in heavy ion collisions.

4 data tables match query

Two-particle CI joint autocorrelations $\widehat{N}(\widehat{r}-1)$ on $(\eta_{\Delta}, \phi_{\Delta})$ for most-central collisions.

Two-particle CI joint autocorrelations $\widehat{N}(\widehat{r}-1)$ on $(\eta_{\Delta}, \phi_{\Delta})$ for mid-central collisions.

Two-particle CI joint autocorrelations $\widehat{N}(\widehat{r}-1)$ on $(\eta_{\Delta}, \phi_{\Delta})$ for mid-peripheral collisions.

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Measurement of the cross section of W-boson pair production at LEP.

The L3 collaboration Achard, P. ; Adriani, O. ; Aguilar-Benitez, M. ; et al.
Phys.Lett.B 600 (2004) 22-40, 2004.
Inspire Record 658254 DOI 10.17182/hepdata.48792

The cross section of W-boson pair-production is measured with the L3 detector at LEP. In a data sample corresponding to a total luminosity of 629.4/pb, collected at centre-of-mass energies ranging from 189 to 209 GeV, 9834 four-fermion events with W bosons decaying into hadrons or leptons are selected. The total cross section is measured with a precision of 1.4 % and agrees with the Standard Model expectation. Assuming charged-lepton universality, the branching fraction for hadronic W-boson decays is measured to be: Br(W-->hadrons) = 67.50 +- 0.42 (stat.) +- 0.30(syst.) %, in agreement with the Standard Model. Differential cross sections as a function of the W- production angle are also measured for the semi-leptonic channels qqev and qqmv.

11 data tables match query

Measured cross section for the process E+ E- --> LEPTON NU LEPTON NU.

Measured cross section for the process E+ E- --> QUARK QUARKBAR ELECTRON NEUTRINO.

Measured cross section for the process E+ E- --> QUARK QUARKBAR MUON NEUTRINO.

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Substructure dependence of jet cross sections at HERA and determination of alpha(s).

The ZEUS collaboration Chekanov, S. ; Derrick, M. ; Loizides, J.H. ; et al.
Nucl.Phys.B 700 (2004) 3-50, 2004.
Inspire Record 650732 DOI 10.17182/hepdata.46136

Jet substructure and differential cross sections for jets produced in the photoproduction and deep inelastic ep scattering regimes have been measured with the ZEUS detector at HERA using an integrated luminosity of 82.2 pb-1. The substructure of jets has been studied in terms of the jet shape and subjet multiplicity for jets with transverse energies Et(jet) > 17 GeV. The data are well described by the QCD calculations. The jet shape and subjet multiplicity are used to tag gluon- and quark-initiated jets. Jet cross sections as functions of Et(jet), jet pseudorapidity, the jet-jet scattering angle, dijet invariant mass and the fraction of the photon energy carried by the dijet system are presented for gluon- and quark-tagged jets. The data exhibit the behaviour expected from the underlying parton dynamics. A value of alphas(Mz) of alphas(Mz) = 0.1176 +-0.0009(stat.) -0.0026 +0.0009 (exp.) -0.0072 +0.0091 (th.) was extracted from the measurements of jet shapes in deep inelastic scattering.

1 data table match query

Measured differential cross section DSIG/DETARAP for inclusive jet production in DIS with ET(C=JET) > 17 GeV. Jets are divided into BROAD and NARROW jets according to their shape.


W boson polarisation at LEP2.

The OPAL collaboration Abbiendi, G. ; Ainsley, C. ; Akesson, P.F. ; et al.
Phys.Lett.B 585 (2004) 223-236, 2004.
Inspire Record 635790 DOI 10.17182/hepdata.49660

Elements of the spin density matrix for W bosons in e+e- -> W+W- -> qqln events are measured from data recorded by the OPAL detector at LEP. This information is used calculate polarised differential cross-sections and to search for CP-violating effects. Results are presented for W bosons produced in e+e- collisions with centre-of-mass energies between 183 GeV and 209 GeV. The average fraction of W bosons that are longitudinally polarised is found to be (23.9 +- 2.1 +- 1.1)% compared to a Standard Model prediction of (23.9 +- 0.1)%. All results are consistent with CP conservation.

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Measurement of the W pair production cross-section and W branching ratios in e+ e- collisions at s**(1/2) = 161-GeV to 209-GeV.

The DELPHI collaboration Abdallah, J. ; Abreu, P. ; Adam, W. ; et al.
Eur.Phys.J.C 34 (2004) 127-144, 2004.
Inspire Record 635851 DOI 10.17182/hepdata.48832

These final results on e+e- -> W+W- production cross-section measurements at LEP2 use data collected by the DELPHI detector at centre-of-mass energies up to 209 GeV. Measurements of total cross-sections, W angular differential distributions and decay branching fractions, and the value of the CKM element |V_{cs}| are compared to the expectations of the Standard Model. These results supersede all values previously published by DELPHI.

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Measurement of K^+K^- production in two-photon collisions in the resonant-mass region

The Belle collaboration Abe, Kazuo ; Abe, Koya ; Abe, T. ; et al.
Eur.Phys.J.C 32 (2003) 323-336, 2003.
Inspire Record 629334 DOI 10.17182/hepdata.50324

K^+K^- production in two-photon collisions has been studied using a large data sample of 67 fb^{-1} accumulated with the Belle detector at the KEKB asymmetric e^+e^- collider. We have measured the cross section for the process gamma gamma -> K^+ K^- for center-of-mass energies between 1.4 and 2.4 GeV, and found three new resonant structures in the energy region between 1.6 and 2.4 GeV. The angular differential cross sections have also been measured.

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Tests of the standard model and constraints on new physics from measurements of fermion pair production at 189-GeV to 209-GeV at LEP

The OPAL collaboration Abbiendi, G. ; Ainsley, C. ; Akesson, P.F. ; et al.
Eur.Phys.J.C 33 (2004) 173-212, 2004.
Inspire Record 628491 DOI 10.17182/hepdata.43174

Cross-section and angular distributions for hadronic and lepton-pair final states in e+e- collisions at centre-of-mass energies between 189 GeV and 209 GeV, measured with the OPAL detector at LEP, are presented and compared with the predictions of the Standard Model. The measurements are used to determine the electromagnetic coupling constant alphaem at LEP2 energies. In addition, the results are used together with OPAL measurements at 91-183 GeV within the S-matrix formalism to determine the gamma-Z interference term and to make an almost model-independent measurement of the Z mass. Limits on extensions to the Standard Model described by effective four-fermion contact interactions or the addition of a heavy Z boson are also presented.

0 data tables match query

Exclusive production of pion and kaon meson pairs in two photon collisions at LEP.

The ALEPH collaboration Heister, A. ; Schael, S. ; Barate, R. ; et al.
Phys.Lett.B 569 (2003) 140-150, 2003.
Inspire Record 626022 DOI 10.17182/hepdata.49730

Exclusive production of π and K meson pairs in two photon collisions is measured with ALEPH data collected between 1992 and 2000. Cross-sections are presented as a function of cos θ ∗ and invariant mass, for | cos θ ∗ |<0.6 and invariant masses between 2.0 and 6.0 GeV/ c 2 (2.25 and 4.0 GeV/ c 2 ) for pions (kaons). The shape of the distributions are found to be well described by QCD predictions but the data have a significantly higher normalization.

0 data tables match query

Proton anti-proton pair production in two photon collisions at LEP

The L3 collaboration Achard, P. ; Adriani, O. ; Aguilar-Benitez, M. ; et al.
Phys.Lett.B 571 (2003) 11-20, 2003.
Inspire Record 620433 DOI 10.17182/hepdata.48883

The reaction e^+e^- -> e^+e^- proton antiproton is studied with the L3 detector at LEP. The analysis is based on data collected at e^+e^- center-of-mass energies from 183 GeV to 209 GeV, corresponding to an integrated luminosity of 667 pb^-1. The gamma gamma -> proton antiproton differential cross section is measured in the range of the two-photon center-of-mass energy from 2.1 GeV to 4.5 GeV. The results are compared to the predictions of the three-quark and quark-diquark models.

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Di-jet production in photon photon collisions at s(ee)**(1/2) = from 189-GeV to 209-GeV.

The OPAL collaboration Abbiendi, G. ; Ainsley, C. ; Akesson, P.F. ; et al.
Eur.Phys.J.C 31 (2003) 307-325, 2003.
Inspire Record 611415 DOI 10.17182/hepdata.49662

Di-jet producion is studied in collisions of quasi-real photons at e+e- centre- of-mass energies sqrt(s)ee from 189 to 209 GeV at LEP. The data were collected with the OPAL detector. Jets are reconstructed using an inclusive k_t clustering algorithm for all cross-section measurements presented. A cone jet algorithm is used in addition to study the different structure of the jets resulting from either of the algorithms. The inclusive di-jet cross-section is measured as a function of the mean transverse energy Etm(jet) of the two leading jets, and as a functiuon of the estimated fraction of the photon momentum carried by the parton entering the hard sub-process, xg, for different regions of Etm (jet). Angular distribution in di-jet events are measured and used to demonstrate the dominance of quark and gluon initiated processes in different regions of phase space. Furthermore the inclusive di-jet cross-section as a function of |eta(jet)| and |delta eta (jet)| is presented where eta(jet) is the jet pseudo-rapidity. Different regions of the xg+ -xg- -space are explored to study and control the influence of an underlying event. The results are compared to next-to-leading order perturbative QCD calculations and to the predictions of the leading order Monte Carlo generator PYTHIA.

0 data tables match query