18123417
BINGO : A Set of Object Oriented Tools for Hierarchical Pattern Recognition and Track Fitting
We describe an object oriented set of tools for carrying out integrated hierarchical pattern recognition in a tracking system composed of an arbitrary set of tracking devices. Two fundamental components are part of the method, a LayerSet object for pattern recognition operations and a TrackFilter object for manipulation of track candidates. The other major components in the package are: a management object that controls the package’s overall operation; a generic input data object capable of holding information from any type of tracking element; and a track candidate object that can receive output from a LayerSet or TrackFilter algorithm. We have implemented a dictionary-based pattern recognition algorithm in this framework.
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.
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.
117292627
Measurement of the charge asymmetry in the decay eta ---> pi+ pi- pi0
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.
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
119252191
Jet trimming
Initial state radiation, multiple interactions, and event pileup can contaminate jets and degrade event reconstruction. Here we introduce a procedure, jet trimming, designed to mitigate these sources of contamination in jets initiated by light partons. This procedure is complimentary to existing methods developed for boosted heavy particles. We find that jet trimming can achieve significant improvements in event reconstruction, especially at high energy/luminosity hadron colliders like the LHC.
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.
63694
Calculating track-based observables for the LHC.
By using observables that only depend on charged particles (tracks), one can efficiently suppress pileup contamination at the LHC. Such measurements are not infrared safe in perturbation theory, so any calculation of track-based observables must account for hadronization effects. We develop a formalism to perform these calculations in QCD, by matching partonic cross sections onto new nonperturbative objects called track functions which absorb infrared divergences. The track function Ti(x) describes the energy fraction x of a hard parton i which is converted into charged hadrons. We give a field-theoretic definition of the track function and derive its renormalization group evolution, which is in excellent agreement with the pythia parton shower. We then perform a next-to-leading order calculation of the total energy fraction of charged particles in e+ e-→ hadrons. To demonstrate the implications of our framework for the LHC, we match the pythia parton shower onto a set of track functions to describe the track mass distribution in Higgs plus one jet events. We also show how to reduce smearing due to hadronization fluctuations by measuring dimensionless track-based ratios.
30709826
Precision jet substructure from boosted event shapes.
Jet substructure has emerged as a critical tool for LHC searches, but studies so far have relied heavily on shower Monte Carlo simulations, which formally approximate QCD at the leading-log level. We demonstrate that systematic higher-order QCD computations of jet substructure can be carried out by boosting global event shapes by a large momentum Q and accounting for effects due to finite jet size, initial-state radiation (ISR), and the underlying event (UE) as 1/Q corrections. In particular, we compute the 2-subjettiness substructure distribution for boosted Z→qq[over ¯] events at the LHC at next-to-next-to-next-to-leading-log order. The calculation is greatly simplified by recycling known results for the thrust distribution in e(+)e(-) collisions. The 2-subjettiness distribution quickly saturates, becoming Q independent for Q > or approximately equal to 400 GeV. Crucially, the effects of jet contamination from ISR/UE can be subtracted out analytically at large Q without knowing their detailed form. Amusingly, the Q=∞ and Q=0 distributions are related by a scaling by e up to next-to-leading-log order.
119475515
Little Technicolor
Inspired by the AdS/CFT correspondence, we show that any G/H symmetry breaking pattern can be described by a simple two-site moose diagram. This construction trivially reproduces the CCWZ prescription in the context of Hidden Local Symmetry. We interpret this moose in a novel way to show that many little Higgs theories can emerge from ordinary chiral symmetry breaking in scaled-up QCD. We apply this reasoning to the simple group little Higgs to see that the same low energy degrees of freedom can arise from a variety of UV complete theories. We also show how models of holographic composite Higgs bosons can turn into brane-localized little technicolor theories by"integrating in"the IR brane.