Inclusive cross sections and invariant single-particle distributions are presented for positive pions and protons produced in 8.05-GeV/c π−p and 18.5-GeV/c π±p inclusive reactions. Distributions in pT2 and in the longitudinal variables x, y (c.m.) and pl (lab) are shown. Comparisons are made with inclusive distributions for other particles produced in the same reactions.
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The ratio of the branching fractions for p p →K + K − and p p →π + π − was determined with the CPLEAR detector, by stopping antiprotons in a gaseous hydrogen target at 15 bar pressure. It was found to be BR(K + K − )/BR( π + π − )=0.205± 0.016. The fraction of P-wave annihilation at rest at this target density was deduced to be (38±9)%.
CONST is the fraction of P-wave annihilation in gaseous hydrogen at pressu re of 15 bar. In the SIG/SIG the statistical and systematic errors are added qu adratically.
We present a new measurement of the K L -K S mass difference ( Δm ) using semileptonic decays of neutral kaons. The measurement yields Δm = (0.5274 ± 0.0029 stat. ± 0.0005 syst. ) × 10 10 ħ/s.
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CP violation has been observed as a time-dependent rate asymmetry between the decays ${⩈erline K}^0 ⌝ghtarrow ≪^{0} ≪^{0}$ and K0 → π0π{0}, where the neutral kaons are produced with definite and individually known strangeness in ${⋏r p}p ⌝ghtarrow{⩈erline K}^0 K^+≪^- $ or p̅p → K0 K− π+. A special technique for the data analysis has been developed. The values obtained for ϕ00 and ¦ η00¦ are in agreement with those of previous measurements of CP violation.
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PI+ PI+ correlations. The correlation function is parametrized as follows R = 1 + CONST(NAME=BEC-LAM)*EXP(-CONST(NAME=BEC-R)**2*MQ**2), where MQ**2 = M(pi1 + pi2)**2 - 4*M(pi)**2.
PI- PI- correlations. The correlation function is parametrized as follows R = 1 + CONST(NAME=BEC-LAM)*EXP(-CONST(NAME=BEC-R)**2*MQ**2), where MQ**2 = M(pi1 + pi2)**2 - 4*M(pi)**N = RE.
The neutral kaon regeneration amplitude in carbon at momenta between 250 and 750 MeV/ c was determined by measuring the interference of inherent and coherently regenerated K S amplitudes. This interference appears in the rates of initially pure (tagged) K 0 and K 0 decaying to π + π − after crossing a carbon absorber.
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Neutral-kaon decays to π e ν were analysed to determine the q 2 dependence of the K 0 e3 electroweak form factor f + . Based on 365 612 events, this form factor was found to have a linear dependence on q 2 with a slope λ + =0.0245±0.0012 stat ±0.0022 syst .
The Q2 dependence of FORMFACTOR+ is usually approximated as: FORMFACTOR+(Q2) = CONST * ( 1 + Q2 * CONST(NAME=LAMBDA+)/M(C=PI)**2).
A high precision study of the process gamma gamma -> p p-bar has been performed using a data sample of 89/fb collected with the Belle detector at the KEKB e+e- collider. The cross section of p p-bar production has been measured at two-photon center-of-mass (c.m.) energies between 2.025 and 4.0 GeV and in the c.m. angular range of |cos(theta^*)|<0.6. Production of gamma gamma -> eta_c -> p p-bar is observed and the product of the two-photon width of the eta_c and its branching ratio to p p-bar is determined.
Measured cross section for GAMMA GAMMA --> PBAR P in the angular region ABS(COS(THETA)) < 0.6.
Measured differential cross sections versus COS(THETA) for the W ranges 2.075 to 2.5, 2.5 to 3.0 and 3.0 to 4.0 GeV.
Measured differential cross sections versus COS(THETA) for the W ranges 2.075 to 2.1, 2.1 to 2.2 and 2.2 to 2.3 GeV.
We present an analysis of charm quark fragmentation at 10.6 GeV, based on a data sample of 103 fb collected by the Belle detector at the KEKB accelerator. We consider fragmentation into the main charmed hadron ground states, namely \DZ, \DP, \Ds and \LC, as well as the excited states \DSZ and \DSP. The fragmentation functions are important to measure as they describe processes at a low energy scale, where calculations in perturbation theory lead to large uncertainties. Fragmentation functions can also be used as input distributions for Monte Carlo generators. Additionally, we determine the average number of these charmed hadrons produced per B decay at the \Ys resonance and measure the distribution of their production angle in \epem annihilation events and in B decays.
We report a measurement of the exclusive $e^+e^- \to D^{(*)\pm}{D}{}^{*\mp}$ cross section as a function of center-of-mass energy near the $D^{(*)^{\pm}}{D}{}^{*\mp}$ threshold with initial state radiation. A partial reconstruction technique is used to increase the efficiency and to suppress background. The analysis is based on a data sample collected with the Belle detector at the $\Upsilon(4S)$ resonance and nearby continuum with an integrated luminosity of 547.8 $\mathrm{fb}^{-1}$ at the KEKB asymmetric-energy $e^+ e^-$ collider.
Cross section for E+ E- --> D*+ D*-.
Cross section for E+ E- --> D+ D*- (plus charged conjugate).
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