Измерено сечение упругого рассеяния фотонов на if-ме- зонах в области S, = (6,5 ± 0,5)1? и &™ = 13(Р ± 3(Р. Из подученных экспериментальных данных определена поляризу емость п-мезона а^+ = (20 ± 12)- Iff*3 см 3
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Results are presented on measured asymmetry parameter in the cross sections of the deuteron photodesintegration by linearly polarized photon beam in the energy range 40-70 MeV for the proton emission angles of 75 and 90 deg in the c. m. s. The experimental data are compared with the theoretical calculations by Partovi, Arenhovel, as well as with calculations performed within an invariant approach with gauge-invariant amplitudes in the pole approximation. The results of the calculation by Arenhovel and the present calculations satisfactorily agree with the experimental data, while the Partovi theory does not describe the asymmetry parameter measurements for photon energies above 40 MeV
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Results of measurements of differential cross sections for the elastic scattering of 11'- mesons of energies 240, 270, 307 and 333 Mev by hydrogen are given.
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The results are given of the measurement of the differential cross sections of charge-exchange scattering of 240, 270, 307, and 333-Mev 1r- mesons on hydrogen.
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The total 1r- -p interaction cross sections (of) were measured with an accuracy of 1.5-2% for about 50 pion energies between 140 and 360 Mev. The pion energy was known to within ± 1%. No anomalies in the energy dependence of Of were found which could indicate the existence of a p0meson with a mass in the range of 270 to 410 Mev/c2• The data are inconsistent with the energy value E2 = 650 Mev for the second maximum of Of found by Frisch et al. 7 but agree with the conclusion drawn by Brisson et al. 8 that it should be located at a lower energy ( E2 :::::: 610 Mev). The data are in agreement with the dispersion relations for 1r- -p scattering. It is thus demonstrated that the PuppiStanghellini problem as such no longer exists and that it arose only as a result of an inaccurate knowledge of the total 1r--p interaction cross section.
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Using the KEDR detector at the VEPP-4M $e^+e^-$ collider, we have measured the values of $R_{\text{uds}}$ and $R$ at seven points of the center-of-mass energy between 3.12 and 3.72 GeV. The total achieved accuracy is about or better than $3.3\%$ at most of energy points with a systematic uncertainty of about $2.1\%$. At the moment it is the most accurate measurement of $R(s)$ in this energy range.
Measured values of $R_{\rm{uds}}(s)$ and $R(s)$ with statistical and systematic uncertainties.
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Hard exclusive electroproduction of $\omega$ mesons is studied with the HERMES spectrometer at the DESY laboratory by scattering 27.6 GeV positron and electron beams off a transversely polarized hydrogen target. The amplitudes of five azimuthal modulations of the single-spin asymmetry of the cross section with respect to the transverse proton polarization are measured. They are determined in the entire kinematic region as well as for two bins in photon virtuality and momentum transfer to the nucleon. Also, a separation of asymmetry amplitudes into longitudinal and transverse components is done. These results are compared to a phenomenological model that includes the pion pole contribution. Within this model, the data favor a positive $\pi\omega$ transition form factor.
The amplitudes of the five sine and two cosine modulations as determined in the entire kinematic region. The results receive an additional 8.2% scale uncertainty corresponding to the target-polarization uncertainty.
The definition of intervals and the mean values of the kinematic variables.
Results on the kinematic dependences of the five asymmetry amplitudes $A_{UT}$ and two amplitudes $A_{UU}$. The first two columns correspond to the $-t'$ intervals $0.00 - 0.07 - 0.20$ GeV$^2$ and the last two columns to the $Q^{2}$ intervals $1.00 - 1.85 - 10.00$ GeV$^2$. The results receive an additional 8.2% scale uncertainty corresponding to the target-polarization uncertainty.
The spin-spin correlation parameter C NN at 50° and 90° c.m. for elastic pp-scattering has been obtained in the energy range 0.69–0.95 GeV. It was found that the parameter C NN (90°) shows resonance-like structure at energies near 700 MeV. Its energy dependence does not agree with Hoshizaki's phase-shift analysis predictions. C NN (50°) agrees well with these predictions and does not show any structure within the accuracy of the measurements.
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The differential cross sections for they+ p-- n + 7T+ process were measured for y-quantum energies 200, 205 and 210 MeV and meson emission angles 16, 24, 36, 44, 56, 64, 76, 84, 96, 104, 116, 124, 136, 144 and 156° relative to the photon beam in the laboratory system. A phenomenological analysis of the results is carried out and some multipole charged-meson photoproduction amplitudes are determined. The results are compared with the predictions of the dispersion-relation theory.
Axis error includes +- 4.8/4.8 contribution.
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Exclusive electroproduction of $\omega$ mesons on unpolarized hydrogen and deuterium targets is studied in the kinematic region of Q$^2$>1.0 GeV$^2$, 3.0 GeV < W < 6.3 GeV, and -t'< 0.2 GeV$^2$. Results on the angular distribution of the $\omega$ meson, including its decay products, are presented. The data were accumulated with the HERMES forward spectrometer during the 1996-2007 running period using the 27.6 GeV longitudinally polarized electron or positron beam of HERA. The determination of the virtual-photon longitudinal-to-transverse cross-section ratio reveals that a considerable part of the cross section arises from transversely polarized photons. Spin density matrix elements are presented in projections of Q$^2$ or -t'. Violation of s-channel helicity conservation is observed for some of these elements. A sizable contribution from unnatural-parity-exchange amplitudes is found and the phase shift between those amplitudes that describe transverse $\omega$ production by longitudinal and transverse virtual photons, $\gamma^{*}_{L} \to \omega_{T}$ and $\gamma^{*}_{T} \to \omega_{T}$, is determined for the first time. A hierarchy of helicity amplitudes is established, which mainly means that the unnatural-parity-exchange amplitude describing the $\gamma^*_T \to \omega_T$ transition dominates over the two natural-parity-exchange amplitudes describing the $\gamma^*_L \to \omega_L$ and $\gamma^*_T \to \omega_T$ transitions, with the latter two being of similar magnitude. Good agreement is found between the HERMES proton data and results of a pQCD-inspired phenomenological model that includes pion-pole contributions, which are of unnatural parity.
The 23 unpolarized and polarized $\omega$ SDMEs from the proton and deuteron data.
The 23 unpolarized and polarized $\omega$ SDMEs for the proton data in $Q^2$ intervals: $1.00 - 1.57 - 2.55 - 10.00$ GeV$^2$.
The 23 unpolarized and polarized $\omega$ SDMEs for the proton data in $-t'$ intervals: $0.000 - 0.044 - 0.105 - 0.200$ GeV$^2$.
The $\Upsilon$(1S), $\Upsilon$(2S), and $\Upsilon$(3S) production cross sections are measured using a data sample corresponding to an integrated luminosity of 35.8 $\pm$ 1.4 inverse picobarns of proton-proton collisions at $\sqrt{s}$ = 7 TeV, collected with the CMS detector at the LHC. The Upsilon resonances are identified through their decays to dimuons. Integrated over the $\Upsilon$ transverse momentum range $p_{t}^{\Upsilon} \lt$ 50GeV and rapidity range |$y^\Upsilon$| $\lt$ 2.4, and assuming unpolarized Upsilon production, the products of the Upsilon production cross sections and dimuon branching fractions are \begin{equation*}\sigma(pp \to \Upsilon(1S) X) . B(\Upsilon(1S) \to \mu^+ \mu^-) = (8.55 \pm 0.05^{+0.56}_{-0.50} \pm 0.34) nb,\end{equation*} \begin{equation*}\sigma(pp \to \Upsilon(2S) X) . B(\Upsilon(2S) \to \mu^+ \mu^-) = (2.21 \pm 0.03^{+0.16}_{-0.14} \pm 0.09) nb,\end{equation*} \begin{equation*}\sigma(pp \to \Upsilon(3S) X) . B(\Upsilon(3S) \to \mu^+ \mu^-) = (1.11 \pm 0.02^{+0.10}_{-0.08} \pm 0.04) nb, \end{equation*} where the first uncertainty is statistical, the second is systematic, and the third is from the uncertainty in the integrated luminosity. The differential cross sections in bins of transverse momentum and rapidity, and the cross section ratios are presented. Cross section measurements performed within a restricted muon kinematic range and not corrected for acceptance are also provided. These latter measurements are independent of Upsilon polarization assumptions. The results are compared to theoretical predictions and previous measurements.
The fiducial and acceptance-corrected cross sections for PT<50 GeV/c and |rapidity|<2.4.
The fiducial and acceptance corrected UPSI(1S) production cross sections (times di-muon branching ratio) as a function of PT for the |rapidity| range < 2.4. Note these are integrated cross sections and the acceptance-corrected cross sections assume the UPSI(1S) are unpolarized with the variations due to the 4 extreme polarization scenarios shown in the last 4 columns. The fiducial cross sections do not need to make any assumptions on the polarizations scenarios. The luminosity uncertainty of 4% is not included in the systematic errors.
The fiducial and acceptance corrected UPSI(2S) production cross sections (times di-muon branching ratio) as a function of PT for the |rapidity| range < 2.4. Note these are integrated cross sections and the acceptance-corrected cross sections assume the UPSI(2S) are unpolarized with the variations due to the 4 extreme polarization scenarios shown in the last 4 columns. The fiducial cross sections do not need to make any assumptions on the polarizations scenarios. The luminosity uncertainty of 4% is not included in the systematic errors.
Invariant mass spectra for jets reconstructed using the anti-kt and Cambridge-Aachen algorithms are studied for different jet "grooming" techniques in data corresponding to an integrated luminosity of 5 inverse femtobarns, recorded with the CMS detector in proton-proton collisions at the LHC at a center-of-mass energy of 7 TeV. Leading-order QCD predictions for inclusive dijet and W/Z+jet production combined with parton-shower Monte Carlo models are found to agree overall with the data, and the agreement improves with the implementation of jet grooming methods used to distinguish merged jets of large transverse momentum from softer QCD gluon radiation.
The unfolded distributions (x1000) for the mean mass of the two leading jets in in dijet events for reconstructed AK7 jets, for the mean PT of the two leading jets in the range 220-300 GeV/c.
The unfolded distributions (x1000) for the mean mass of the two leading jets in in dijet events for reconstructed AK7 jets, for the mean PT of the two leading jets in the range 300-450 GeV/c.
The unfolded distributions (x1000) for the mean mass of the two leading jets in in dijet events for reconstructed AK7 jets, for the mean PT of the two leading jets in the range 450-500 GeV/c.
The production of the X(3872) is studied in pp collisions at sqrt(s) = 7 TeV, using decays to J/psi pi pi, where the J/psi decays to two muons. The data were recorded by the CMS experiment and correspond to an integrated luminosity of 4.8 inverse femtobarns. The measurements are performed in a kinematic range in which the X(3872) candidates have a transverse momentum 10 < pt < 50 GeV and rapidity abs(y) < 1.2. The ratio of the X(3872) and psi(2S) cross sections times their branching fractions into J/psi pi pi is measured as a function of pt. In addition, the fraction of X(3872) originating from B decays is determined. From these measurements the prompt X(3872) differential cross section times branching fraction as a function of pt is extracted. The pi pi mass spectrum of the J/psi pi pi system in the X(3872) decays is also investigated.
Ratio between the differential X(3872) and PSI(2S) cross sections times branching fractions with (R) and without (R_fiducial) acceptance corrections.
Ratio between the total X(3872) and PSI(2S) cross sections times branching fractions with (R) and without (R_fiducial) acceptance corrections.
Nonprompt X(3872) fraction without acceptance corrections.
The underlying event activity in proton-proton collisions at forward pseudorapidity (-6.6 < eta < -5.2) is studied with the CMS detector at the LHC, using a novel observable: the ratio of the forward energy density, dE/d(eta), for events with a charged-particle jet produced at central pseudorapidity (abs(eta[jet]) < 2) to the forward energy density for inclusive events. This forward energy density ratio is measured as a function of the central jet transverse momentum, pt, at three different pp centre-of-mass energies (sqrt(s) = 0.9, 2.76, and 7 TeV). In addition, the sqrt(s) evolution of the forward energy density is studied in inclusive events and in events with a central jet. The results are compared to those of Monte Carlo event generators for pp collisions and are discussed in terms of the underlying event. Whereas the dependence of the forward energy density ratio on jet pt at each sqrt(s) separately can be well reproduced by some models, all models fail to simultaneously describe the increase of the forward energy density with sqrt(s) in both inclusive events and in events with a central jet.
Ratio of the energy deposited in the pseudorapidity range $-6.6 < \eta < -5.2$ for events with a charged-particle jet with $|\eta^\text{jet}| < 2$ with respect to the energy in inclusive events, as a function of the jet transverse momentum $p_{\rm T}$ for $\sqrt{s} =$ 0.9, 2.76 , and 7 TeV. Data are taken from the Rivet Analysis.
The top-quark pair production cross section in 7 TeV center-of-mass energy proton–proton collisions is measured using data collected by the CMS detector at the LHC. The measurement uses events with one jet identified as a hadronically decaying τ lepton and at least four additional energetic jets, at least one of which is identified as coming from a b quark. The analyzed data sample corresponds to an integrated luminosity of 3.9 fb(−1) recorded by a dedicated multijet plus hadronically decaying τ trigger. A neural network has been developed to separate the top-quark pairs from the W+jets and multijet backgrounds. The measured value of is consistent with the standard model predictions.
The measured cross section for top-quark pair production.
The W+W- and ZZ production cross sections are measured in proton-proton collisions at sqrt(s) = 8 TeV with the CMS experiment at the LHC in data samples corresponding to an integrated luminosity of up to 5.3 inverse femtobarns. The measurements are performed in the leptonic decay modes W+W- to l' nu l'' nu and ZZ to 2l 2l', where l = e, mu and l'(l'') = e, mu, tau. The measured cross sections sigma(pp to W+W-) = 69.9 +/- 2.8 (stat.) +/- 5.6 (syst.) +/- 3.1 (lumi.) pb and sigma(pp to ZZ) = 8.4 +/- 1.0 (stat.) +/- 0.7 (syst.) +/- 0.4 (lumi.) pb, for both Z bosons produced in the mass region 60 < m[Z] < 120 GeV, are consistent with standard model predictions. These are the first measurements of the diboson production cross sections at sqrt(s) = 8 TeV.
The measured cross section for W+ W- production performed in the W --> LEPTONPRIME NU mode where LEPTONPRIME is electron, muon or tau.
The measured cross section for Z0Z0 production performed in the Z0 --> LEPTON LEPTONPRIME mode where LEPTON is E or MU and LEPTONPRIME is E, MU or TAU.
Measurements of event shapes and azimuthal correlations are presented for events where a Z boson is produced in association with jets in proton-proton collisions. The data collected with the CMS detector at the CERN LHC at sqrt(s) = 7 TeV correspond to an integrated luminosity of 5.0 inverse femtobarns. The analysis provides a test of predictions from perturbative QCD for a process that represents a substantial background to many physics channels. Results are presented as a function of jet multiplicity, for inclusive Z boson production and for Z bosons with transverse momenta greater than 150 GeV, and compared to predictions from Monte Carlo event generators that include leading-order multiparton matrix-element (with up to four hard partons in the final state) and next-to-leading-order simulations of Z + 1-jet events. The experimental results are corrected for detector effects, and can be compared directly with other QCD models.
Normalized DPhi(Z, j1) distributions for Njets >= 1.
Normalized DPhi(Z, j1) distributions for Njets >= 2.
Normalized DPhi(Z, j1) distributions for Njets >= 3.
Measurements of inclusive jet and dijet production cross sections are presented. Data from LHC proton-proton collisions at $\sqrt{s}$ = 7 TeV, corresponding to 5.0 inverse femtobarns of integrated luminosity, have been collected with the CMS detector. Jets are reconstructed up to rapidity 2.5, transverse momentum 2 TeV, and dijet invariant mass 5 TeV, using the anti-k$_t$ clustering algorithm with distance parameter R = 0.7. The measured cross sections are corrected for detector effects and compared to perturbative QCD predictions at next-to-leading order, using five sets of parton distribution functions.
Inclusive Jet Cross Section for |rapidity| < 0.5 as a function of the jet transverse momentum. The (sys) error is the total systematic error, including the luminosity uncertainty of 2.2%.
Inclusive Jet Cross Section for |rapidity| 0.5 TO 1.0 as a function of the jet transverse momentum. The (sys) error is the total systematic error, including the luminosity uncertainty of 2.2%.
Inclusive Jet Cross Section for |rapidity| 1.0 TO 1.5 as a function of the jet transverse momentum. The (sys) error is the total systematic error, including the luminosity uncertainty of 2.2%.
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