Active cooling control of the CLEO detector using a hydrocarbon coolant farm

We describe a novel approach to particle-detector cooling in which a modular farm of active coolant-control platforms provides independent and regulated heat removal from four recently upgraded subsystems of the CLEO detector: the ring-imaging Cherenkov detector, the drift chamber, the silicon vertex detector, and the beryllium beam pipe. We report on several aspects of the system: the suitability of using the aliphatic-hydrocarbon solvent PF(TM)-200IG as a heat-transfer fluid, the sensor elements and the mechanical design of the farm platforms, a control system that is founded upon a commercial programmable logic controller employed in industrial process-control applications, and a diagnostic system based on virtual instrumentation. We summarize the system's performance and point out the potential application of the design to future high-energy physics apparatus.Comment: 21 pages, LaTeX, 5 PostScript figures; version accepted for publication in Nuclear Instruments and Methods in Physics Research

Branching Fractions of tau Leptons to Three Charged Hadrons

From electron-positron collision data collected with the CLEO detector operating at CESR near \sqrt{s}=10.6 GeV, improved measurements of the branching fractions for tau decays into three explicitly identified hadrons and a neutrino are presented as {\cal B}(\tau^-\to\pi^-\pi^+\pi^-\nu_\tau)=(9.13\pm0.05\pm0.46)%, {\cal B}(\tau^-\to K^-\pi^+\pi^-\nu_\tau)=(3.84\pm0.14\pm0.38)\times10^{-3}, {\cal B}(\tau^-\to K^-K^+\pi^-\nu_\tau)=(1.55\pm0.06\pm0.09)\times10^{-3}, and {\cal B}(\tau^-\to K^-K^+K^-\nu_\tau)<3.7\times10^{-5} at 90% C.L., where the uncertainties are statistical and systematic, respectively.Comment: 10 pages postscript, also available through http://w4.lns.cornell.edu/public/CLNS, to appear in Phys. Rev. Let

Charmonium absorption by nucleons

$J/\Psi$ dissociation in collisions with nucleons is studied within a boson exchange model and the energy dependence of the dissociation cross section is calculated from the threshold for $\Lambda_c{\bar D}$ production to high energies. We illustrate the agreement of our results with calculations based on short distance QCD and Regge theory. The compatibility between our calculations and the data on $J/\Psi$ photoproduction on a nucleon is discussed. We evaluate the elastic $J/\Psi{+}N$ cross section using a forward dispersion relation and demonstrate the overall agreement with the predictions from QCD sum rules. Our results are compatible with the phenomenological dissociation cross section evaluated from the experimental data on $J/\Psi$ production from $\gamma{+}A$, $p{+}A$ and $A{+}A$ collisions.Comment: 14 pages, revtex, including 13 figures, accepted for publication in Phys. Rev.

Improved Measurement of the Form Factors in the Decay Lambda_c^+ --> Lambda e^+ nu_e

Using the CLEO detector at the Cornell Electron Storage Ring, we have studied the distribution of kinematic variables in the decay Lambda_c^+ -> Lambda e^+ nu_e. By performing a four-dimensional maximum likelihood fit, we determine the form factor ratio, R = f_2/f_1 = -0.31 +/- 0.05(stat) +/- 0.04(syst), the pole mass, M_{pole} = (2.21 +/- 0.08(stat) +/- 0.14(syst)) GeV/c^2, and the decay asymmetry parameter of the Lambda_c, alpha_{Lambda_c} = -0.86 +/- 0.03(stat) +/- 0.02(syst), for = 0.67 (GeV/c^2)^2. We compare the angular distributions of the Lambda_c^+ and Lambda_c^- and find no evidence for CP-violation: A_{Lambda_c} = (alpha_{Lambda_c^+} + alpha_{Lambda_c^-})/ (alpha_{Lambda_c^+} - alpha_{Lambda_c^-}) = 0.00 +/- 0.03(stat) +/- 0.01(syst) +/- 0.02, where the third error is from the uncertainty in the world average of the CP-violating parameter, A_{Lambda}, for Lambda -> p pi^-.Comment: 8 pages postscript,also available through http://www.lns.cornell.edu/public/CLNS/2004/, submitted to PR

Evidence for B^(*)_s bar{B}^(*)_s Production at the Upsilon(5S)

Using data collected by the CLEO III detector at CESR, we started a series of investigations on the Upsilon(5S) resonance decay properties. The data sample used for this analysis consists of 0.42 fb-1 of data taken on the Upsilon(5S) resonance, 6.34 fb-1 of data collected on the Upsilon(4S) and 2.32 fb-1 of data taken in the continuum below the Upsilon(4S). B_s mesons are expected to decay predominantly into D_s meson, while the lighter B mesons decay into D_s only about 10% of the time. We exploit this difference to make a preliminary model dependent estimate of the ratio of B_s(*) anti-B_s(*) to the total b anti-b quark pair production at the Upsilon(5S) energy to be (21 +- 3 +- 9)%.Comment: 17 pages postscript,also available through http://www.lns.cornell.edu/public/CONF/2004/, Presented at ICHEP Aug 16-22,2004, Beijing, Chin

Measurements of the Branching Fractions and Helicity Amplitudes in B --> D* rho Decays

Using 9.1 fb-1 of e+ e- data collected at the Upsilon(4S) with the CLEO detector using the Cornell Electron Storage Ring, measurements are reported for both the branching fractions and the helicity amplitudes for the decays B- -> D*0 rho- and B0bar -> D*+ rho-. The fraction of longitudinal polarization in B0bar -> D*+ rho- is found to be consistent with that in B0bar -> D*+ l- nubar at q^2 = M^2_rho, indicating that the factorization approximation works well. The longitudinal polarization in the B- mode is similar. The measurements also show evidence of non-trivial final-state interaction phases for the helicity amplitudes.Comment: 11 pages postscript, also available through http://w4.lns.cornell.edu/public/CLNS, submitted to PR

Excitation functions of hadronic observables from SIS to RHIC energies

We calculate excitation functions for various dynamical quantities as well as experimental observables from SIS to RHIC energies within the HSD transport approach which is based on string, quark, diquark ($q, \bar{q}, qq, \bar{q}\bar{q}$) and hadronic degrees of freedom without including any explicit phase transition to a quark-gluon plasma (QGP). It is argued that the failure of this more 'conventional' approach in comparison to experimental data should indicate the presence of a different phase which might be either attributed to space-time regions of vanishing scalar quark condensate ($$ = 0) or to the presence of a QGP phase with strongly interacting partons. We study the $K/\pi$ ratio, the low mass dilepton enhancement in the invariant mass regime from 0.2 -- 1.2 GeV as well as charmonium suppression for central Au + Au collisions as a function of the bombarding energy and present predictions for these observables as well as hadron rapiditiy distributions at RHIC energies. Whereas all observables studied within HSD show smooth increasing/decreasing excitation functions, the experimental $K^+/\pi^+$ ratio indicates a maximum at 11 A$\cdot$GeV (or above) which is interpreted as a signature for a chirally restored phase in the course of the reaction.Comment: 34 pages, LaTeX, including 14 postscript figures (high quality color versions of figs. 3,4 are available from http://theorie.physik.uni-giessen.de/~brat/own.html), Nucl. Phys.

Search for the Decay τ−→4pi−3π+(π0)ντ\tau^{-}\to 4pi^{-}3\pi^{+}(\pi^{0})\nu_{\tau}

We have searched for the decay of the tau lepton into seven charged particles and zero or one pi0. The data used in the search were collected with the CLEO II detector at the Cornell Electron Storage Ring (CESR) and correspond to an integrated luminosity of 4.61 fb^(-1). No evidence for a signal is found. Assuming all the charged particles are pions, we set an upper limit on the branching fraction, B(tau- -> 4pi- 3pi+ (pi0) nu_tau) < 2.4 x 10^(-6) at the 90% confidence level. This limit represents a significant improvement over the previous limit.Comment: 9 page postscript file, postscript file also available through http://w4.lns.cornell.edu/public/CLN