The reaction π − p→K + K − n has been studied on a hydrogen target (27 000 events) at 18.4 GeV/ c and on a polarized target (54 000 events) at 17.2 GeV/ c . A combination of results of both experiments allows a partial-wave analysis of the K + K − system between 1.1 and 1.74 GeV mass without any model assumptions. In general our fits yield unique solutions. Using results of our previous analysis of π + π − final states and assuming the dominance of the positive G -parity states in the K + K − system, the branching ratios BR ( K K /ππ) of partial waves into K K and ππ are determined. The S-wave appears to be mainly a broad ε (1300) with BR ( K K /ππ) = 0.068 −0.021 +0.017 . The weak P-wave can be described by a tail of the ϱ(770) with BR ( K K /ππ) = 0.081 −0.025 +0.029 . The D-wave is interpreted in terms of a superposition of f(1270) + A 2 (1310) + f′(1515) resonances. The fit yields BR ( K K /ππ) = 0.069 −0.031 +0.023 for the f(1270) and BR( ππ /all) = 0.027 −0.013 +0.071 for the f′(1515). The F-wave shows the g(1690) meson with BR ( K K /ππ) = 0.191 −0.037 +0.040 . All the above values refer to the t bin between 0.01 and 0.20 (GeV/ c ) 2 . Some results are also given for the high- t region.
PARTIAL-WAVE INTENSITIES AND BRANCHING RATIOS.
We present results from the NA32 experiment at CERN on the production characteristics of the charmed baryon Λ + c in 230 GeV π − Cu and K − Cu interactions. A high resolution vertex detector consisting of change-coupled devices and silicon microstrip detectors allowed the selection of a very clean sample of 154 Λ + c → pK − π + (and charge conjugate) decays. Results on differential and integrated cross sections are given.
No description provided.
No description provided.
Using data from the NA32 experiment at CERN we have studied the Λ + c decays containing a Σ + among the decay products. The interactions of 230 GeV π − with a Cu target were analysed using a precise vertex telescope (charge-coupled devices and silicon microstrip detectors) and the ACCMOR spectrometer. We have found eleven Λ + c →Σ + π + π − , one Λ + c →Σ + K + K − , two Λ + c →Σ + K + π − and one Λ + c →Σ + π + π − π + π − decays practically without any backgroun d. We have measured the branching ratios with respect to the Λ + c →pK − π + channel.
No description provided.
An experiment has been performed to search for associated hadronic production of charmed mesons, using a large-aperture forward magnetic spectrometer setup in a π − beam at the CERN SPS. A prompt electron trigger was used to select events containing a pair by charmed particles. D mesons have been identified by reconstruction of hadronic decay modes such as Kπ, Kππ. Data have been taken at 120, 175, and 200 GeV, The D D cross section measured at 175 200 GeV is σ( D D ) = (48 ± 15) μ b with a systematic uncertainty of ±50%. The energy dependence of the cross section is measured to be σ( D D ) [120 GeV )/σ( D D [175/200 GeV ] = 0.62 ± 0.34 .
No description provided.
No description provided.
None
AUTHORS FIT D2(SIG)/D(XL)/D(PT**2) BY (1-XL)**POWER*EXP(-SLOPE*PT**2).
AUTHORS FIT D2(SIG)/D(XL)/D(PT**2) BY (1-XL)**POWER*EXP(-SLOPE*PT**2).
AUTHORS FIT D2(SIG)/D(XL)/D(PT**2) BY (1-XL)**POWER*EXP(-SLOPE*PT**2).
Inclusive ϕ-meson production has been measured for 100 GeV/cK−,\(\bar p\) andp incident on a Be target. Differential cross sectionsdσ/dxF anddσ/dp⊥2 are presented in the interval 0.075<xF<0.225 and 0<p⊥<1 GeV/c respectively. The shape of thedσ/dxF distributions agrees with predictions from a quark fusion model. Comparison with cross sections measured on a hydrogen target in the samexF andp⊥ range suggest a linearA-dependence fromA=1 toA=9.
No description provided.
We have observed four unambiguous decays of the charmed strange baryon Ξ c o in the NA32 experiment at CERN. Charge- coupled devices and silicon microstrip detectors were used to reconstruct the decay mode Ξ c o → pK − K ∗ (892) o seen in events produced by the interaction of 230 GeV/ c negative poins and kaons on a copper target. We present the first measurement of the lifetime of the Ξ c o , together with a determination of its mass and production cross section. The resonant components of the Ξ c o decay are studied. We use our earlier measurement of the mass of the Ξ c + in the determination of the isospin mass splitting of the Ξ c states.
No description provided.
We have observed six unambiguous decays of the charmed strange baryon Ξ c + (or charge conjugate Ξ c − ) in the 230 GeV/c negative pions or kaons on a copper target at the CERN SPS using silicon microstrip detectors and charge-coupled devices for vertex reconstruction. Three of them have been reconstructed through the decay chain Ξ c + → Ξ − π + π + , Ξ − → Λ 0 π − , Λ 0 → pπ − and the other three through the decay chain Ξ c + → Σ + K − π + → pπ 0 . We present our measurements of the mass, lifetime and production cross-section of the Ξ c + , as well as of the branching ration for the two decay modes.
The cross sections times branching ratio, linear A-dependence is assumed.
A search has been made for the hadronic production of charmed baryons and mesons with a large aperture forward magnetic spectrometer using 150 GeV protons originating from the CERN-SPS. A prompt electron trigger was used as a signature for charm. Upper limits at 90% confidence level have been obtained for the production of Λ c + D 0 , D 0 D + and D − : σ(Λ c ) ⩽ 8 μ b , σ( D 0 ) ⩽ 64 μ b , σ( D 0 ) < 37 μ b , σ( D + ) ⩽ 51 μ b and σ( D − ) ⩽ 49 μ b per nucleon, assuming linear A dependence. Systematic errors due to uncertainties in branching ratios and to model dependence of the acceptance calculation are discussed.
No description provided.
We report on the production of inclusive $\Upsilon$(1S) and $\Upsilon$(2S) in p-Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV at the LHC. The measurement is performed with the ALICE detector at backward ($-4.46< y_{{\rm cms}}<-2.96$) and forward ($2.03< y_{{\rm cms}}<3.53$) rapidity down to zero transverse momentum. The production cross sections of the $\Upsilon$(1S) and $\Upsilon$(2S) are presented, as well as the nuclear modification factor and the ratio of the forward to backward yields of $\Upsilon$(1S). A suppression of the inclusive $\Upsilon$(1S) yield in p-Pb collisions with respect to the yield from pp collisions scaled by the number of binary nucleon-nucleon collisions is observed at forward rapidity but not at backward rapidity. The results are compared to theoretical model calculations including nuclear shadowing or partonic energy loss effects.
Inclusive UPSI(1S) production cross section as a function of rapidity in p-Pb collisions at sqrt(s_NN) = 5.02 TeV. The data was collected in 2013 with two beam configurations, p-Pb and Pb-p with integrated luminosities of 5.0 nb-1 and 5.8 nb-1, respectively.
Inclusive UPSI(1S) production cross section as a function of rapidity in p-Pb collisions at sqrt(s_NN) = 5.02 TeV. The data was collected in 2013 with two beam configurations, p-Pb and Pb-p with integrated luminosities of 5.0 nb-1 and 5.8 nb-1, respectively.
Inclusive UPSI(2S) production cross section as a function of rapidity in p-Pb collisions at sqrt(s_NN) = 5.02 TeV. The data was collected in 2013 with two beam configurations, p-Pb and Pb-p with integrated luminosities of 5.0 nb-1 and 5.8 nb-1, respectively.
Forum