121999587
Operational performance of a large liquid argon photon calorimeter
Abstract We describe the performance of a large (0.9 × 1.4 m2) liquid argon photon calorimeter in high energy experiments at Fermilab. Resolutions for π0 and electron showers, obtained under data-taking conditions, are compared with electron-beam calibration results. Exceptional spatial and time resolutions have been achieved for isolated showers (σx,y
121484834
Avoidance of counter-example to non-abelian Bloch-Nordsieck conjecture by using coherent state approach
It is shown that the counter-example to the non-abelian Bloch-Nordsieck conjecture in “q + q → γ∗ + soft gluons” to order αs2 is avoided at the cross section level if the initial st prepared according to the coherent state approach for treatment of the infrared region of non-abelian gauge theories.
9914814
Design and Operating Experience with Electronic Systems for High Rate Liquid Argon Calorimeters
A number of experiments have been instrumented by an ADC scheme utilizing an integrated amplifier, a packaged delay line, the difference of two samples taken Before and After the signal exits the delay, and a multiplexer to a single ADC for a system. This paper discusses design features, operating peculiarities, and experience to date.
118487890
Search for photoproduction of psi (3105)
21840141
Commissioning of the control and data acquisition electronics for the CDF silicon vertex detector
The SVX (silicon vertex detector) data acquisition system includes three components: a Fastbus sequencer, an SVX rabbit crate controller, and a digitizer. These modules are integrated into the Collider Detector Facility (CDF) data acquisition system and operate the readout chips. The results of the extensive functional tests of the SVX modules are reported. The authors discuss the sequencer's stability, systematic differences between them, and methods of synchronization with the Tevatron beam crossing. The digitizer ADC (analog-to-digital converter) calibration procedure run on the microsequencer is described. The microsequencer code used for data taking and SVX chip calibration modes is described. Measurements of the SVX data scan time under different conditions are discussed.<<ETX>>
183079972
Operating Characteristics of Lecroy-2280/2285 ADC System
11827113
DETERMINATIONS OF P, AND CP, FOR HEAVY MESONS AND TESTS FOR THEIR VIOLATIONS WITHOUT POLARIZATION EXPERIMENTS
Powerful results are tabulated which can be used at modern colliders to make fundamental symmetry tests by analysis of sequential decays of X + V1V2. By generalization of the ty$ parity test which has recently been used to determine the parity of the r|c, the P (or CP) quantum number can always be determined for X of any spin J which decays P (or respectively CP) invariantly into VV or VV where each vector meson decays into two spin-0 bosons, or is (0. P can also always be determined from a mode like K + K °. A neutral spin-0 technipion and an elementary Higgs particle, for instance, can be distinguished by such CP invariant decay modes and by <j>p , <j)J, JT, or i£ sufficiently massive by <f>Z° or JZ° where J/\JJ and Z° go into a lepton-antilepton pair. Generalization to the gZ° and gg decay channels, g = gluon jet, which would be relevant to new resonance physics, for example, at the CERN collider is discussed. There are also very simple tests for possible violations of P, of the combination of C plus isospin, of both P and CP, and of both C and CP. The practicality and state-of-the-art property of the c)><|> parity test /1/ has been recently demonstrated by its use /2/ by the Mark III collaboration at SLAC-SPEAR to determine the parity of the t) . Less than twenty events were needed to measure the dependence of the decay correlation function I((ji) = 1 + 6 cos2<f) on the azimuthal angle <j> between the two <f> -* K+KT decay planes and to show agreement with B = -1 (pseudoscalar), instead of 0 <_ 6 <_ 1 (scalar). This (j)(j) parity test /1/ for a spin-zero particle was proposed by Ngee-Pong Chang and myself in 1978 as an analogue of Yang's parity test /3/ for the ir°. By means of the h'elicity formalism /4/, it was soon elegantly generalized /5/ by Trueman for a decaying X particle of any spin J. In the last few months the test has been extended /6,7/ to other V1V2 decay modes, for X of any spin J, including those of neutral X particles with odd chargeconjugation and those of charged X states. It has also been found that a spin-0 technipion and an elementary Higgs particle can be distinguished by a decay mode like (jxj) or JJ (identical vector mesons), K*°K ° (particle-antiparticle pair), <j)p°, <J)J, JT, or if sufficiently massive by cfiZ or JZO where j/t|i and Z° go into a leptonantilepton pair. In this talk we will summarize these new results, explain what has to be measured, and tabulate what can be learned from analysis of specific V1V2 decay modes. Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1985229 c2-262 JOURNAL DE PHYSIQUE The advantages of t h i s type of t e s t a r e t h a t it i s r igorous, t h a t t he s ignatures a r e s t r i k i n g , t h a t t he P/CP determination i s independent of t he po la r i za t ion s t a t e of t he decaying X system (and so the t e s t is independent of t he production mechanism), t h a t t he P/CP determination never f a i l s f o r J=0 o r when the re i s a Vlt*.V2 exchange property, and t h a t the t e s t i s normally applicable i n semi-inclusive p roduc t i on experiments s ince many X decay modes y i e ld observed s t a t e s with only charged pa r t i c l e s . We w i l l f i r s t consider t he following sequent ia l decay of an X system of any spin J X + v1 v2 Spin 0 mesons A1, B1, ... In t he X r e s t frame the nine h e l i c i t y amplitudes a r e speci f ied by where X = XI-X2 and @ , @ a r e the polar and azimuthal angles of V l . By Lorentzinvariance t h e general decay co r r e l a t i on funct ion is 161 + Bd(01,02) cos 2$ + Bx(01,02) s i n 2+ where the polar angles el and 82 f o r A 1 and A2 momenta a r e defined /5,6/ a s i n Fig. 1. In pa r t i cu l a r , although the azimuthal angle 4 i s invar iant under Lorentz boosts
122358666
Production thresholds for quark and for diquark pairs in ee-bar annihilation as tests of charm, then color, excitation
We have pointed out earlier that the decrease at high energies in the ratio of charged-particle energy to total energy in ee-bar annihilation into hadrons and the rise in R in the 4-GeV region suggest first charm, then color, excitation. We present here an analysis of the pair-production thresholds for quarks (responsible for ..mu..e events) and for diquarks (threshold near 4.3 GeV) based on the simple mass spectrum generated by the popular color-octet vector-meson-exchange mechanism, but here in the context of R data and the integrally charged three-quartet model. Our emphasis throughout is a phenomenological one, with special attention to experimental signatures in annihilation and lepton-pair production which can exclude this economical model. For this spectrum we find there must exist a new color-symmetry-violating coupling responsible for the decays of quarks. From the identification of the U particles as quarks, it is suggested that this includes a weak interaction mediated by colored, right-handed quark-neutrino currents coupled to the usual charged currents.
14270584
Tau decays beyond the standard model
In a recent paper, 8 semileptonic parameters were defined to specify the most general Lorentz-invariant spin correlation functions for 2-body τ decays. These parameters can be used to search for anomalous Γ L , Γ T polarized-partial widths, for non-CKM-type leptonic CP violation, and for leptonic T FS violation. They can also be used to bound the effective-mass scales A for “new physics” arising from additional Lorentz structures, e.g. from lepton compositeness, tau weak magnetism, weak electricity, or second-class currents. It is emphasized that (i) for these tests “different modes have different merits” and that (ii) the parameters can be measured either by using spin-correlation techniques without polarized beams, or with longitudinally polarized beams.
121474561
Color models of hadrons
Abstract The evidence for a three-valued “color” degree of freedom in hadron physics is reviewed. The structure of color model is discussed. Consequences of color models for elementary particle physics are discussed, including saturation properties of hadronic states, π o → 2 ψ and related decays, leptoproduction, and lepton pair annihilation. Signatures are given which distinguish theories with isolated colored particles from those in which color is permanently bound.
119907461
Parity determination for the new generation of heavy neutral mesons
We consider how best to experimentally determine the parity quantum number of a new heavy neutral meson, including the possibility of exotic ${J}^{\mathrm{PC}}$. Multiquark and gluon bound states can have exotic ${J}^{\mathrm{PC}}$ quantum numbers forbidden to the nonrelativistic $q\overline{q}$ system. If only the existence of easily identifiable two-body hadronic modes is known, it is not possible to establish the parity so an "exotic" meson, $Jg0$, could be misidentified as a "normal" meson. Direction-linear-polarization coefficients, which would identify the parity, are also found to be small for $e\overline{e}\ensuremath{\rightarrow}{1}^{\ensuremath{-}\ensuremath{-}}\ensuremath{\rightarrow}{1}^{\ifmmode\pm\else\textpm\fi{}+}\ensuremath{\gamma},{0}^{\ifmmode\pm\else\textpm\fi{}+}\ensuremath{\gamma}$ with the high-energy photon externally converting into an $e\overline{e}$ pair. However, important parity tests do exist, independent of the polarization state of the decaying particle, which can be used to settle the confusion. These are listed in Sec. III of this paper.