The ALICE Collaboration has measured inclusive J/psi production in pp collisions at a center of mass energy sqrt(s)=2.76 TeV at the LHC. The results presented in this Letter refer to the rapidity ranges |y|<0.9 and 2.5<y<4 and have been obtained by measuring the electron and muon pair decay channels, respectively. The integrated luminosities for the two channels are L^e_int=1.1 nb^-1 and L^mu_int=19.9 nb^-1, and the corresponding signal statistics are N_J/psi^e+e-=59 +/- 14 and N_J/psi^mu+mu-=1364 +/- 53. We present dsigma_J/psi/dy for the two rapidity regions under study and, for the forward-y range, d^2sigma_J/psi/dydp_t in the transverse momentum domain 0<p_t<8 GeV/c. The results are compared with previously published results at sqrt(s)=7 TeV and with theoretical calculations.
Double differential J/$\psi$ production cross section at $\sqrt{s}=2.76$ TeV. The first uncertainty is statistical, the second one is $p_{\rm T}$-coorelated, the third one is uncorrelated. Polarization-related uncertainties are not included.
The $\sqrt{s}$-dependence of $\langle p_{\rm T}\rangle$ for inclusive J/$\psi$ production (forward rapidity).
the $\sqrt{s}$-dependence of $\langle p_{\rm T}\rangle$ for inclusive J/$\psi$ production (forward rapidity).
|Tz|=32Δ(1238) systems are studied from the standpoint of direct production utilizing experimental data on the reactions pp→pπ+n, pp→pπ+π−p, pp→pπ+π−π0p, and pp→pπ+π−π+n. Resonance-production total and differential cross sections are presented, in addition to the decay density-matrix elements. It is demonstrated that the experimentally defined Δ(1238) systems are not characterized solely by spin-parity 32+, and that corresponding elements of the density matrices of both pπ+ and π−n cases generally behave in a similar manner with increasing c.m. angle. Additional detailed studies of the t-channel moments are presented for peripherally produced πN systems as a function of both c.m. angle and πN invariant mass. Dynamical differences are observed between the pπ+ and nπ− moments for the very peripheral data. One-pion-exchange-model predictions are compared with the peripheral pπ+ moments and with several invariant-mass distributions from the pp→pπ+π−p data. Complications arising from the presence of two pπ+ combinations in the four- and five-body final-state data are discussed.
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A systematic study has been made of the reactions pp→pp and pp→pN* in the angular range from θlab=10∘ to θc.m.=90∘ at 3, 4, 5, 6, and 7 GeVc. An orthogonal dispersion magnetic spectrometer detected protons from interactions in hydrogen with momentum transfer (−t) in excess of 0.5 (GeV)2. Well-defined peaks in the missing-mass spectra occurred at average N* masses of 1240±6, 1508±2, and 1683±3 MeV with average full widths of 102±4, 92±3, and 110±4 MeV, respectively. Below 2400 MeV no other significant enhancements were found. The N* production cross sections dσdt near θc.m.=90∘ are in qualitative agreement with the predictions of the statistical model. For each isobar the differential cross section at fixed energy varies as exp(−vv0), where v≡[−tu(t+u)]; v0 varies systematically with energy and tends toward the same value (≈0.4 GeV2) for each isobar at the upper limit of our energy range.
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