The cross section for the production of Z gamma in proton-proton collisions at 8 TeV is measured based on data collected by the CMS experiment at the LHC corresponding to an integrated luminosity of 19.5 inverse femtobarns. Events with an oppositely-charged pair of muons or electrons together with an isolated photon are selected. The differential cross section as a function of the photon transverse momentum is measured inclusively and exclusively, where the exclusive selection applies a veto on central jets. The observed cross sections are compatible with the expectations of next-to-next-to-leading-order quantum chromodynamics. Limits on anomalous triple gauge couplings of Z Z gamma and Z gamma gamma are set that improve on previous experimental results obtained with the charged lepton decay modes of the Z boson.
Inclusive fiducial cross sections in bins of pT(gamma) with statistical, systematic, and luminosity uncertainties, respectivley. Results are not divided by bin-widths. The last bin is the cross section for pT(gamma) > 120 GeV. Combined result of electron and muon channels.
Fiducial cross sections with jet-veto in bins of pT(gamma) with statistical, systematic, and luminosity uncertainties, respectivley. Results are not divided by bin-widths. The last bin is the cross section for pT(gamma) > 120 GeV. Combined result of electron and muon channels.
Ratio of fiducial cross section with jet-veto and the inclusive cross section in bins of pT(gamma). The last bin is the cross section for pT(gamma) > 120 GeV. Combined result of electron and muon channels.
InclusiveKs0, Λ and\(\bar \Lambda\)-production has been investigated in\(\bar p\)p-interactions at 22.4 GeV/c. Total and topological cross sections and multiplicity characteristics of neutral strange particles have been determined. DifferentialKs0 and Λ-cross sections and also characteristics of annihilation processes with neutral kaon production have been studied. It is shown that the difference of the shapes of the invariantx-distributions forK-mesons in the fragmentation region for annihilation and non-annihilation processes can be described in the framework of the “dual” valon model, but not by considering the current (undressed) quark recombination mechanisms only. The polarization of Λ and\(\bar \Lambda\)-hyperons has been measured.
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A high-statistics measurement of the differential cross-sections for neutrino-iron scattering in the wide-band neutrino beam at the CERN SPS is presented. Nucleon structure functions are extracted and theirQ2 evolution is compared with the predictions of quantum chromodynamics.
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Using data from the Fermilab 15 ft hydrogen bubble chamber, we have studied inclusive ϱ 0 production in antineutrino-proton charged-current interactions. We measure (0.21 ± 0.03) ϱ 0 /event, corresponding to ϱ 0 / π − =0.12 ± 0.02. As a function of Q 2 and for hadronic masses above a threshold region, the ϱ 0 / π − ratio shows little variation. At least 50% of the ϱ 0 's are consistent with coming from the current fragmentation region. The results agree reasonably well with the predictions of the quark fragmentation model of Feynman and field.
AVERAGE BEAM ENERGY 31 GEV.
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Inclusive charged-current interactions of high-energy neutrinos and antineutrinos have been studied with high statistics in a counter experiment at the CERN Super Proton Synchrotron. The energy dependence of the total cross-sections, the longitudinal structure function, and the nucleon structure functionsF2,xF3, and\(\bar q^{\bar v} \) are determined from these data. The analysis of theQ2-dependence of the structure functions is used to test quantum chromodynamics, to determine the scale parameter Λ and the gluon distribution in the nucleon.
ABSOLUTE FLUXES HAVE NOT BEEN MEASURED. NORMALISED TO OLD RESULTS.
STUCTURE FUNCTIONS ARE EVALUATED ASSUMING R=SIG(L)/SIG(T)=0.1 AND M(W) IS INFINITE. NO CORRECTION FOR FERMI MOTION APPLIED. ERRORS ARE STATISTICAL AND SYSTEMATIC POINT-TO-POINT ERRORS. IN ADDITION OVER-ALL SCALE ERROR OF 6 PCT. FOR F2 , 8 PCT. FOR XF3.
STUCTURE FUNCTIONS ARE EVALUATED ASSUMING R=SIG(L)/SIG(T)=0.1 AND M(W) IS INFINITE. NO CORRECTION FOR FERMI MOTION APPLIED. ERRORS ARE STATISTICAL AND SYSTEMATIC POINT-TO-POINT ERRORS. IN ADDITION OVER-ALL SCALE ERROR OF 6 PCT. FOR F2 , 8 PCT. FOR XF3.
Inclusive neutrino and antineutrino charged-current interactions were studied using the electronic detector of the CHARM Collaboration exposed to the narrow-band beam of the CERN SPS. The relative contributions of quarks and antiquarks to the neutrino cross sections were deduced from the differential cross sectionsdσ/d y . The x and Q 2 dependence of the structure functions F 2 and F 3 were measured. Scaling violations were observed, in qualitative agreement with QCD. A value of the mass scale parameter of QCD,Λ = [0.29 ± 0.12 (stat.) ± 0.10 (syst.)] GeV, was deduced in a leading-order approximation, following the method of Buras and Gaemers.
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After completion of the data taking for the νμ→ντ oscillation search, the CHORUS lead–scintillator calorimeter was used in the 1998 run as an active target. High-statistics samples of charged-current interactions were collected in the CERN SPS west area neutrino beam. This beam contained predominantly muon (anti-)neutrinos from sign-selected pions and kaons. We measure the flux and energy spectrum of the incident neutrinos and compare them with beam simulations. The neutrino–nucleon and anti-neutrino–nucleon differential cross-sections are measured in the range 0.01<x<0.7 , 0.05<y<0.95 , 10<Eν<200 GeV . We extract the neutrino–nucleon structure functions F2(x,Q2) , xF3(x,Q2) , and R(x,Q2) and compare these with results from other experiments.
The measured F2 and xF3 at X = 0.020.
The measured F2 and xF3 at X = 0.045.
The measured F2 and xF3 at X = 0.080.
The inclusive cross section and the average multiplicity are evaluated for most of the charged ( π ± , p, K ± ) and neutral (γ, π 0 , K 0 , K 0 , Λ, Λ , n ) particles produced in 32 GeV/ c K − p interactions; corresponding results are obtained for each charged topology separately. New results are given for the total charged multiplicity cross sections. The average longitudinal momentum of neutrals is found to be roughly equal to that of charged particles. The π + and π − multiplicity distributions are reconstructed and compared to the π 0 and to the total charged multiplicity distributions.
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Axis error includes +- 30/30 contribution (SYSTEMATIC ERROR FOR K0 MULTIPLICITY, WHICH IS EVALUATED FROM 2 ASSUMPTIONS: ALL K0'S COME FROM THE FINAL STATES (N K 2AK PIONS) OR (LAMBDA/SIGMA K AK PIONS) AND CHARGE DISTRIBUTION IN THESE FINAL STATES OBEYS A STATISTICAL ISOSPIN MODEL OF F.CERULUS,NC 19, 528. ALSO ASSUMED THAT SIG(K+)=SIG(KO). VALUES OF SIG(XI-) AND RATIOS SIG(SIGMA+)/SIG(LAMBDA), SIG(SIGMA-)/SIG(LAMBDA) ARE TAKEN FROM 14.3 GEV EXPERIMENT LOUEDEC 76,NC 41A, 166, STATISTICAL ERRORS BEING DOUBLED. FOR ALL ANTIBARYONS ASSUMED THAT SIG(ANTIBARYON)/SIG(BARYON)=SIG(ANTILAMBDA)/SIG(LAMBDA) =0.046+-0.020. SLOW PROTONS WITH PLAB < 1.2 GEV/C ARE IDENTIFIED, AN ESTIMATE FOR FAST PROTON PRODUCTION IS TAKEN FROM FACCINI 77,NP B127, 109).
Axis error includes +- 30/30 contribution (SYSTEMATIC ERROR FOR K0 MULTIPLICITY, WHICH IS EVALUATED FROM 2 ASSUMPTIONS: ALL K0'S COME FROM THE FINAL STATES (N K 2AK PIONS) OR (LAMBDA/SIGMA K AK PIONS) AND CHARGE DISTRIBUTION IN THESE FINAL STATES OBEYS A STATISTICAL ISOSPIN MODEL OF F.CERULUS,NC 19, 528. ALSO ASSUMED THAT SIG(K+)=SIG(KO). VALUES OF SIG(XI-) AND RATIOS SIG(SIGMA+)/SIG(LAMBDA), SIG(SIGMA-)/SIG(LAMBDA) ARE TAKEN FROM 14.3 GEV EXPERIMENT LOUEDEC 76,NC 41A, 166, STATISTICAL ERRORS BEING DOUBLED. FOR ALL ANTIBARYONS ASSUMED THAT SIG(ANTIBARYON)/SIG(BARYON)=SIG(ANTILAMBDA)/SIG(LAMBDA) =0.046+-0.020. SLOW PROTONS WITH PLAB < 1.2 GEV/C ARE IDENTIFIED, AN ESTIMATE FOR FAST PROTON PRODUCTION IS TAKEN FROM FACCINI 77,NP B127, 109).
Exposures of the Ne/H 2 filled Big European Bubble Chamber (BEBC) to a dichromatic neutrino (antineutrino) beam produced by 400 GeV protons of the CERN SPS yielded ∼ 3100 events with a negative, and ∼ 1100 with a positive, muon. The neutrino flux is determined from the muon flux in the shielding. Assuming a linear energy dependence of the cross section, the values σ E between 20 and 200 GeV are found to be 0.657 ± 0.012 (stat.) ± 0.027 (syst.) and 0.309 ± 0.009 (stat.) ± 0.013 (syst.) cm 2 (GeV nucleon) −1 , for neutrinos and antineutrinos, respectively. The scaling variable q 2 E decreases significantly with increasing energy both for neutrinos and antineutrinos.
Measured charged current total cross section.
Measured charged current total cross section.
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Total neutrino and antineutrino cross sections in the energy range 15 to 150 GeV, and the nucleon structure functions, F 2 ( x , Q 2 ) and xF 3 ( x , Q 2 ) in the Q 2 range 0.5 to 50 (GeV/ c ) 2 have been measured using a data sample of 3000 neutrino and 3800 antineutrino events. The structure functions show a weak Q 2 dependence at different x values.
Measured charged current total cross section.
Measured charged current total cross section.
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