10716932
A new approach to track finding and fitting in vector drift chambers
Abstract We describe the algorithm that is used to find and fit charged particle trajectories in the Mark III detector at SPEAR. The computer program uses a novel non-numerical pattern recognition technique analogous to that used by the digital hardware in the experiment's track finding trigger processor. The technique is both fast and efficient. The complete reconstruction of events is performed at a rate of 37 ms per track on an IBM 3081K, compared with 91 ms per track with a more conventional technique. A preliminary fit of all tracks, suitable for online monitoring, is available after 15 ms per track. Similar techniques are also applicable to future experiments operating in high multiplicity environments. The organization of the algorithms is such as to lead to simple implementation on vector processors.
38939426
Observation of inclusive B decays to the charmed baryons Sigma c++ and Sigma c0.
Using data collected in the region of the [Upsilon](4[ital S]) resonance with the CLEO II detector operating at the Cornell Electron Storage Ring, we report on evidence for the production of [Sigma][sub [ital c]][sup ++] and [Sigma][sub [ital e]][sup 0] baryons in [ital B] decays, with [Sigma][sub [ital c]][r arrow][Lambda][sub [ital c]][sup +][pi]. This observation is based on 77[plus minus]19[Sigma][sub [ital c]][sup ++] and 76[plus minus]21[Sigma][sub [ital c]][sup 0] candidates from [ital B] decays. We find the product branching fractions [ital scrB]([ital [bar B]][r arrow][Sigma][sub [ital c]][ital X])[ital scrB]([Lambda][sub [ital c]][sup +][r arrow][ital pK][sup [minus]][pi][sup +]) for [Sigma][sub [ital c]]=[Sigma][sub [ital c]][sup ++], [Sigma][sub [ital c]][sup 0], and [Sigma][sub [ital c]][sup +] to be (2.1[plus minus]0.8[plus minus]0.7)[times]10[sup [minus]4], (2.3[plus minus]0.8[plus minus]0.7)[times]10[sup [minus]4], and less than 4.8[times]10[sup [minus]4] at 90% confidence level, respectively. A study of the [Sigma][sub [ital c]][sup ++] and [Sigma][sub [ital c]][sup 0] momentum spectra indicates that [ital B] decays to two-body final states with [Sigma][sub [ital c]] are suppressed.
17397470
Inclusive decays of B mesons to charmonium.
We have used the CLEO-II detector at the Cornell Electron Storage Ringe (CESR) to study the inclusive production of charmonium mesons in a sample of 2.15 million {ital B{bar B}} events. We find inclusive branching fractions of (1.12{plus_minus}0.04{plus_minus}0.06)% for {ital B}{r_arrow}{ital J}/{psi}{ital X}, (0.34{plus_minus}0.04{plus_minus}0.03)% for {ital B}{r_arrow}{psi}{prime}{ital X}, and (0.40{plus_minus}0.06{plus_minus}0.04)% for {ital B}{r_arrow}{chi}{sub {ital c}1}{ital X}. We also find some evidence for the inclusive production of {chi}{sub {ital c}2}, and set an upper limit for the branching fraction of the inclusive decay {ital B}{r_arrow}{eta}{sub {ital c}}{ital X} of 0.9% at 90% confidence level. Momentum spectra for inclusive {ital J}/{psi}, {psi}{prime}, and {chi}{sub {ital c}1} production are presented. These measurements are compared to theoretical calculations.
121630940
Heavy quarks and tau
I present some recent experimental results on τ, charm, and bottom physics. CVC test and Michel parameters of the τ; mixing and fDs; and fB, Nc, η'K, ππ and Kπ, Vcb and Vub, lifetime and mixing, and CP violation searches in B decays.
61210509
A HIGH SPEED DATA ACQUISITION SUBSYTEM FOR THE SSC
3 1: Introduction 3 2: Scopeof Our Work 6 3: Componentsof a DataAcquisition System 8 4: Milestones 21 5: Personnel 22 6: Budget 23 References 27
117292627
Measurement of the charge asymmetry in the decay eta ---> pi+ pi- pi0
118395989
Anomaly mediation from unbroken supergravity
A bstractWhen supergravity (SUGRA) is spontaneously broken, it is well known that anomaly mediation generates sparticle soft masses proportional to the gravitino mass. Recently, we showed that one-loop anomaly-mediated gaugino masses should be associated with unbroken supersymmetry (SUSY). This counterintuitive result arises because the underlying symmetry structure of (broken) SUGRA in flat space is in fact (unbroken) SUSY in anti-de Sitter (AdS) space. When quantum corrections are regulated in a way that preserves SUGRA, the underlying AdS curvature (proportional to the gravitino mass) necessarily appears in the regulated action, yielding soft masses without corresponding goldstino couplings. In this paper, we extend our analysis of anomaly mediation to sfermion soft masses. Already at tree-level we encounter a number of surprises, including the fact that zero soft masses correspond to broken (AdS) SUSY. At one-loop, we explain how anomaly mediation appears when regulating SUGRA in a way that preserves super-Weyl invariance. We find that recent claims in the literature about the non-existence of anomaly mediation were based on a Wilsonian effective action with residual gauge dependence, and the gauge-invariant 1PI effective action contains the expected anomaly-mediated spectrum. Finally, we calculate the sfermion spectrum to all orders, and use supertrace relations to derive the familiar two-loop soft masses from minimal anomaly mediation, as well as unfamiliar tree-level and one-loop goldstino couplings consistent with renormalization group invariance.
119243170
Hadron Mass Effects in Power Corrections to Event Shapes
We study the effect of hadron masses on the leading power correction of dijet event-shape distributions. We define the transverse velocity operator, that describes the effects of hadron masses. It depends on the "transverse velocity" r, which is different from one only for non-vanishing hadron masses. We find that hadron-mass effects in general break universality. However we provide a simple method to identify universality classes of event shapes with a common power correction. We also compute the anomalous dimension of the power correction and the structure of the corresponding Wilson coefficient, finding a nontrivial result.
7293408
Semi-annihilation of dark matter
We show that the thermal relic abundance of dark matter can be affected by a new type of reaction: semi-annihilation. Semi-annihilation takes the schematic form ψiψj → ψkφ, where ψi are stable dark matter particles and φ is an unstable state. Such reactions are generically present when dark matter is composed of more than one species with “flavor” and/or “baryon” symmetries. We give a complete set of coupled Boltzmann equations in the presence of semi-annihilations, and study two toy models featuring this process. Semi-annihilation leads to non-trivial dark matter dynamics in the early universe, often dominating over ordinary annihilation in determining the relic abundance. This process also has important implications for indirect detection experiments, by enriching the final state spectrum from dark matter (semi-)annihilation in the Milky Way.
14915502
Reverse) engineering vacuum alignment
In the presence of spontaneous symmetry breaking, the alignment of the vacuum with respect to the gauge group is often controlled by quadratically divergent operators in the low energy non-linear sigma model. In principle the magnitudes and signs of these operators can be changed by making different assumptions about the ultraviolet physics, but in practice all known ways of regulating these theories preserve the naive vacuum alignment. We show that by ``integrating in'' different sets of heavy spin-one fields, it is possible to UV extend certain non-linear sigma models into two distinct UV insensitive theories. These UV extensions have identical low energy degrees of freedom but different radiative potentials, making it possible to engineer two different vacuum alignments for the original non-linear sigma model. Our construction employs ``non-square'' theory spaces which generically violate the common lore that the preferred vacuum alignment preserves the maximal gauge symmetry. By UV extending the SO(9)/(SO(4) × SO(5)) little Higgs model, we find a radiative potential that deviates from the naive expectation but does not stabilize the correct vacuum for proper electroweak symmetry breaking.
10781940
Universal dynamics of spontaneous Lorentz violation and a new spin-dependent inverse-square law force
We study the universal low-energy dynamics associated with the spontaneous breaking of Lorentz invariance down to spatial rotations. The effective lagrangian for the associated Goldstone field can be uniquely determined by the non-linear realization of a broken time diffeomorphism symmetry, up to some overall mass scales. It has previously been shown that this symmetry breaking pattern gives rise to a Higgs phase of gravity, in which gravity is modified in the infrared. In this paper, we study the effects of direct couplings between the Goldstone boson and standard model fermions, which necessarily accompany Lorentz-violating terms in the theory. The leading interaction is the coupling to the axial vector current, which reduces to spin in the non-relativistic limit. A spin moving relative to the ``ether rest frame will emit Goldstone Cerenkov radiation. The Goldstone also induces a long-range inverse-square law force between spin sources with a striking angular dependence, reflecting the underlying Goldstone shockwaves and providing a smoking gun for this theory. We discuss the regime of validity of the effective theory describing these phenomena, and the possibility of probing Lorentz violations through Goldstone boson signals in a way that is complementary to direct tests in some regions of parameter space.