The PHENIX experiment at the Relativistic Heavy Ion Collider has measured the differential cross section, mean transverse momentum, mean transverse momentum squared of inclusive $J/\psi$ and cross-section ratio of $\psi(2S)$ to $J/\psi$ at forward rapidity in \pp collisions at \sqrts = 510 GeV via the dimuon decay channel. Comparison is made to inclusive $J/\psi$ cross sections measured at \sqrts = 200 GeV and 2.76--13 TeV. The result is also compared to leading-order nonrelativistic QCD calculations coupled to a color-glass-condensate description of the low-$x$ gluons in the proton at low transverse momentum ($p_T$) and to next-to-leading order nonrelativistic QCD calculations for the rest of the $p_T$ range. These calculations overestimate the data at low $p_T$. While consistent with the data within uncertainties above $\approx3$ GeV/$c$, the calculations are systematically below the data. The total cross section times the branching ratio is BR $d\sigma^{J/\psi}_{pp}/dy (1.2<|y|<2.2, 0<p_T<10~\mbox{GeV/$c$}) =$ 54.3 $\pm$ 0.5 (stat) $\pm$ 5.5 (syst) nb.
The total cross section times the branching ratio.
The inclusive $J/\psi$ differential cross section as a function of $p_T$ at 1.2 < $|y|$ < 2.2 at 510 GeV.
The inclusive $J/\psi$ differential cross section integrated over 0 < $p_T$ < 10 GeV/$c$ as a function of rapidity at 510 GeV.
Inclusive K 0 -production has been measured in e + e - annihilation at a center of mass energy of about W = 30 GeV. The ratio of K 0 + K 0 production to μ + μ - production is R K 0 = 5.6 ± 1.1 (statist. error) ± 0.8 (system.error) This value is about a factor of three higher than R K 0 at W = 7 GeV. The cross sections ( s / β ) d σ /d x is consistent with a scaling behaviour.
No description provided.
DIFFERENTIAL CROSS SECTION.
INVARIANT CROSS SECTION.
Using a data sample with a total integrated luminosity of 10.0 pb$^{-1}$ collected at center-of-mass energies of 2.6, 3.07 and 3.65 GeV with BESII, cross sections for $e^+e^-$ annihilation into hadronic final states ($R$ values) are measured with statistical errors that are smaller than 1%, and systematic errors that are about 3.5%. The running strong interaction coupling constants $\alpha_s^{(3)}(s)$ and $\alpha_s^{(5)}(M_Z^2)$ are determined from the $R$ values.
R values.
The PHENIX experiment has measured $\phi$ meson production in $d$$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV using the dimuon and dielectron decay channels. The $\phi$ meson is measured in the forward (backward) $d$-going (Au-going) direction, $1.2<y<2.2$ ($-2.2<y<-1.2$) in the transverse-momentum ($p_T$) range from 1--7 GeV/$c$, and at midrapidity $|y|<0.35$ in the $p_T$ range below 7 GeV/$c$. The $\phi$ meson invariant yields and nuclear-modification factors as a function of $p_T$, rapidity, and centrality are reported. An enhancement of $\phi$ meson production is observed in the Au-going direction, while suppression is seen in the $d$-going direction, and no modification is observed at midrapidity relative to the yield in $p$$+$$p$ collisions scaled by the number of binary collisions. Similar behavior was previously observed for inclusive charged hadrons and open heavy flavor indicating similar cold-nuclear-matter effects.
Invariant yields of $\phi$ meson production as a function of $p_T$ at different $d$+Au centrality classes. Type B represents uncertainties that are correlated from point to point.
Invariant yields of $\phi$ meson production as a function of $p_T$ at different $d$+Au centrality classes. Type B represents uncertainties that are correlated from point to point.
Invariant yields of $\phi$ meson production as a function of $p_T$ at different $d$+Au centrality classes. Type B represents uncertainties that are correlated from point to point.
The PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC) has measured $\phi$ meson production and its nuclear modification in asymmetric Cu$+$Au heavy-ion collisions at $\sqrt{s_{NN}}=200$ GeV at both forward Cu-going direction ($1.2<y<2.2$) and backward Au-going direction ($-2.2<y<-1.2$), rapidities. The measurements are performed via the dimuon decay channel and reported as a function of the number of participating nucleons, rapidity, and transverse momentum. In the most central events, 0\%--20\% centrality, the $\phi$ meson yield integrated over $1<p_T<5$ GeV/$c$ prefers a smaller value, which means a larger nuclear modification, in the Cu-going direction compared to the Au-going direction. Additionally, the nuclear-modification factor in Cu$+$Au collisions averaged over all centrality is measured to be similar to the previous PHENIX result in $d$$+$Au collisions for these rapidities.
Invariant yield as a function of the number of participating nucleons for 1.2 < $|y|$ < 2.2 and 1 < $p_T$ < 5 GeV/$c$. Type A represents uncertainties that are uncorrelated from point to point, Type B represents uncertainties that are correlated from point to point, and Type C represents uncertainties in the overall normalization.
Invariant yield as a function of transverse momentum for 1.2 < $|y|$ < 2.2 and 0%–93% centrality. Type A represents uncertainties that are uncorrelated from point to point, Type B represents uncertainties that are correlated from point to point, and Type C represents uncertainties in the overall normalization.
Invariant yield as a function of rapidity for 1 < $p_T$ < 5 GeV/$c$ and 0%–93% centrality. Type A represents uncertainties that are uncorrelated from point to point, Type B represents uncertainties that are correlated from point to point, and Type C represents uncertainties in the overall normalization.
Differential cross sections for the reaction $\gamma p \to n \pi^+$ have been measured with the CEBAF Large Acceptance Spectrometer (CLAS) and a tagged photon beam with energies from 0.725 to 2.875 GeV. Where available, the results obtained here compare well with previously published results for the reaction. Agreement with the SAID and MAID analyses is found below 1 GeV. The present set of cross sections has been incorporated into the SAID database, and exploratory fits have been made up to 2.7 GeV. Resonance couplings have been extracted and compared to previous determinations. With the addition of these cross sections to the world data set, significant changes have occurred in the high-energy behavior of the SAID cross-section predictions and amplitudes.
Differential cross sections for incident photon energies 0.725, 0.775, 0.825and 0.875 GeV.
Differential cross sections for incident photon energies 0.925, 0.975, 1.025and 1.075 GeV.
Differential cross sections for incident photon energies 1.125, 1.175, 1.225and 1.275 GeV.
The process e + e − → π 0 + anything has been measured at c.m. energies of 14 and 34 GeV for π 0 energies between 0.5 and 4 GeV. The ratio of π 0 to π ± production for π momenta between 0.5 and 1.5 GeV/ c is measured to be 2 σ ( π 0 )/ [ σ ( π + ) + σ ( π − )] = 1.3 ± 0.4 (1.2 ± 0.4) at 14 (34) GeV. The scaled cross section ( s / μ )d σ /d x when compared with lower energy (4.9–7.4 GeV) π 0 data indicates a substantial scaling violation.
COMPARISON OF PI0 WITH CHARGED PION CROSS SECTIONS (SCALED BI 1/S TO SAME ENERGIES).
No description provided.
No description provided.
Results onK0 and Λ production ine+e− annihilation at c.m. energies of 14, 22 and 34 GeV are presented. The shape of theK0 and Λ differential cross sections are very similar to each other and to those of π±,K± and\(p(\bar p)\). Scaling violations are observed forK0 production. We obtain a value for the probability to produce strange quark-antiquark pairs relative to that to produce up or down quark-antiquark pairs of 0.35±0.02±0.05. The value ofRh=σ(e+e-→hX)/σµµ is shown to rise steadily with c.m. energy for all particle species. At 34 GeV we find 1.48±0.05K0 and 0.31±0.03 Λ per event. We have searched for possible Λ polarization. The production ofK0's and Λ's in jets is examined as a function ofpT2 and rapidity and compared to that of all charged particles; the yields in two and three jets are also investigated. Results are presented from events with two baryons\((\Lambda ,\bar \Lambda ,por\bar p)\) observed.
No description provided.
No description provided.
No description provided.
The Beijing Spectrometer (BES) experiment has observed purely leptonic decays of the Ds meson in the reaction e+e−→Ds+Ds− at a c.m. energy of 4.03 GeV. Three events are observed in which one Ds decays hadronically to φπ, K¯*0K, or K¯0K, and the other decays leptonically to μνμ or τντ. With the assumption of μ−τ universality, values of the branching fraction, B(Ds→μνμ)=(1.5−0.6−0.2+1.3+0.3)%, and the Ds pseudoscalar decay constant, fDs=(4.3−1.3−0.4+1.5+0.4)×102 MeV, are obtained.
No description provided.
In this table CONST is the pseudoscalar decay constant, f_[D/S].
Measurements of elastic photoproduction cross sections for the J / ψ meson from 100 GeV to 375 GeV are presented. The results indicate that the cross section increases slowly in this range. The shape of the energy dependence agrees well with the photon-gluon fusion model prediction.
Data supplied by V. Paolone.
Cross section data using Bethe-Heitler event normalization.
Cross section data using the Beam Gamma Monitor normalization.
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