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Articles 1 - 30 of 33
Full-Text Articles in Physical Sciences and Mathematics
Inclusive Production Of Neutral Pions In Hadronic Z Decays, R. Barate, M. Thulasidas
Inclusive Production Of Neutral Pions In Hadronic Z Decays, R. Barate, M. Thulasidas
Research Collection School Of Computing and Information Systems
A measurement of the inclusive production of π0 mesons in hadronic Z decays is presented and compared to Monte Carlo model predictions. The analysis is based on approximately 2 million hadronic events recorded with the ALEPH detector at LEP at a centre-of-mass energy of ⊡s = 91.2 GeV. Neutral pions are reconstructed using photons measured in the electromagnetic calorimeter and photons from conversion pairs. The inclusive π0 momentum spectrum is measured in the range 0.025 x p = p/p beam 0 per hadronic Z is found to be 4.80 ± 0.07(stat) ± 0.31(sys). The differential inclusive π0 cross section is …
Tertiary Storage In Multimedia Systems: Staging Or Direct Access?, Hwee Hwa Pang
Tertiary Storage In Multimedia Systems: Staging Or Direct Access?, Hwee Hwa Pang
Research Collection School Of Computing and Information Systems
Multimedia applications that are required to manipulate large collections of objects are becoming increasingly common. Moreover, the size of multimedia objects, which are already huge, are getting even bigger as the resolution of output devices improve. As a result, many multimedia storage systems are not likely to be able to keep all of their objects disk-resident. Instead, a majority of the less popular objects have to be off-loaded to tertiary storage to keep costs down. The speed at which objects can be accessed from tertiary storage is thus an important consideration. In this paper, we propose an adaptive data retrieval …
Updated Measurement Of The Τ Lepton Lifetime, R. Barate, Manoj Thulasidas
Updated Measurement Of The Τ Lepton Lifetime, R. Barate, Manoj Thulasidas
Research Collection School Of Computing and Information Systems
A new measurement of the mean lifetime of the τ lepton is presented. Three different analysis methods are applied to a sample of 90000 τ pairs, collected in 1993 and 1994 with the ALEPH detector at LEP. The average of this measurement and those previously published by ALEPH is ττ = 290.1±1.5±1.1fs.
Searches For Scalar Top And Scalar Bottom Quarks At Lep2, Barate, R.; Et Al., M. Thulasidas
Searches For Scalar Top And Scalar Bottom Quarks At Lep2, Barate, R.; Et Al., M. Thulasidas
Research Collection School Of Computing and Information Systems
Searches for scalar top and bottom quarks have been performed with data collected by the ALEPH detector at LEP. The data sample consists of 21.7 pb−1 taken at √ s = 161, 170, and 172 GeV and 5.7 pb−1 taken at √ s = 130 and 136 GeV. No evidence for scalar top quarks or scalar bottom quarks was found in the channels ˜t → cχ, ˜t → bℓν˜, and b˜ → bχ. For the channel ˜t → cχ a limit of 67 GeV/c 2 has been set on the scalar top quark mass, independent of the mixing angle between …
Search For The Standard Model Higgs Boson In E+E- Collisions At √S = 161, 170 And 172 Gev, Barate, R.; Et Al., M. Thulasidas
Search For The Standard Model Higgs Boson In E+E- Collisions At √S = 161, 170 And 172 Gev, Barate, R.; Et Al., M. Thulasidas
Research Collection School Of Computing and Information Systems
The reaction e+ e ! HZ is used to search for the Standard Model Higgs boson. The data sample consists of integrated luminosities of 10:9 pb1 , 1:1 pb1 , and 9:5 pb1 collected by the ALEPH experiment at LEP during 1996, at centre-of-mass energies of 161, 170 and 172 GeV, respectively. No candidate events were found, in agreement with the expected background of 0.84 events from all Standard Model processes. This search results in a 95% C.L. lower limit on the Higgs boson mass of 69:4 GeV=c2 . When combined with earlier ALEPH searches performed at energies at and …
Inclusive Decays B->Dx And B->D*X, L. Gibbons, Manoj Thulasidas
Inclusive Decays B->Dx And B->D*X, L. Gibbons, Manoj Thulasidas
Research Collection School Of Computing and Information Systems
We report new measurements of the differential and total branching ratios for inclusive B decay to D-0, D+, and D*+ and the first measurement of the same quantities for inclusive B decay to D-*0. Here B is the mixture of B-d and B-u from Y(4S) decay. Furthermore, since more than one charm particle (or antiparticle) of the same kind can be produced in B decay, here ''inclusive B branching ratio'' is used to mean the average number of charm particles and their antiparticles of a certain species: produced in B decay. We obtain the following results (the first error is …
Search For Sleptons In E+E- Collisions At Centre-Of-Mass Energies Of 161 Gev And 172 Gev, R. Barate, Manoj Thulasidas
Search For Sleptons In E+E- Collisions At Centre-Of-Mass Energies Of 161 Gev And 172 Gev, R. Barate, Manoj Thulasidas
Research Collection School Of Computing and Information Systems
The data recorded by the ALEPH experiment at LEP at centre–of–mass energies of 161 GeV and 172 GeV were analysed to search for sleptons, the supersymmetric partners of leptons. No evidence for the production of these particles was found. The number of candidates observed is consistent with the background expected from four–fermion processes and γγ–interactions. Improved mass limits at 95% C.L. are reported.
A Measurement Of The Qcd Colour Factors And A Limit On The Light Gluino, Barate, R.; Et Al., M. Thulasidas
A Measurement Of The Qcd Colour Factors And A Limit On The Light Gluino, Barate, R.; Et Al., M. Thulasidas
Research Collection School Of Computing and Information Systems
Using data collected from 1992 to 1995 with the ALEPH detector at LEP, a measurement of the colour factor ratios CA/CF and TF /CF and the strong coupling constant αs = CFαs(MZ)/(2π) has been performed by fitting theoretical predictions simultaneously to the measured differential two-jet rate and angular distributions in four-jet events. The result is found to be in excellent agreement with QCD, {fx4-1} Fixing CA/CF and TF/CF to the QCD values permits a determination of αs(MZ) and ηf, the number of active flavours. With this measurement the existence of a gluino with mass below 6.3 GeV/c2 is excluded at …
Multiple Representation For Understanding Data Structures, Biffah Hancies, Venky Shankararaman, Jose Munoz
Multiple Representation For Understanding Data Structures, Biffah Hancies, Venky Shankararaman, Jose Munoz
Research Collection School Of Computing and Information Systems
In this paper an approach to enhance the learning of abstract computing concepts by novice students is presented. This approach is based on effective use of multiple visual representations, and it was applied within the domain of linear data structures: array, stack, queue and linked list. A prototype computer-based instructional system called MRUDS (Multiple Representation for Understanding Data Structures) was developed and evaluated. It was found from the evaluation that the three presentation modules namely, analogy, representation and algorithm contributed to the students' learning process, each contributing to and reinforcing the effect of the others.
Measurement Of The Transverse Spin Correlations In The Decay Z → Τ+Τ-, Barate, R.; Et Al., M. Thulasidas
Measurement Of The Transverse Spin Correlations In The Decay Z → Τ+Τ-, Barate, R.; Et Al., M. Thulasidas
Research Collection School Of Computing and Information Systems
A measurement of the transverse-transverse, CTT, and transverse-normal CTN, τ spin correlations in the decay Z0 → τ+ τ− is presented based on the aplanarity angle of the decay products of both taus. Based on 80 pb−1 of data collected by ALEPH[1] in 1992, 1993 and 1994 on the peak of the Z resonance, the results are: CTT = 1.00 ± 0.14(stat) ± 0.04(syst), CTN =−0.08 ± 0.14(stat) ± 0.02(syst). These values are in agreement with the Standard Model predictions, CTT = 0.989 and CTN = 0.
Search For The Bc Meson In Hadronic Z Decays, R. Barate, Manoj Thulasidas
Search For The Bc Meson In Hadronic Z Decays, R. Barate, Manoj Thulasidas
Research Collection School Of Computing and Information Systems
A search for the Bc meson decaying into the channels Jψπ+ and Jψℓ+νℓ (ℓ = e or μ) is performed in a sample of 3.9 million hadronic Z decays collected by the ALEPH detector. This search results in the observation of 0 and 2 candidates in each of these channels, respectively, while 0.44 and 0.81 background events are expected. The following 90% confidence level upper limits are derived:Br(Z→BcXBr(Z→qq̄Br(Bc+→Jψπ+)
Measurement Of The Branching Fraction For D0 → K-Π+, R. Barate, M. Thulasidas
Measurement Of The Branching Fraction For D0 → K-Π+, R. Barate, M. Thulasidas
Research Collection School Of Computing and Information Systems
The branching fraction for D0 → K−π+ is measured with the statistics collected by ALEPH from 1991 to 1994. The method is based on the comparison between the rate for the reconstructed D∗+→ D0π+, D0 → K−π+ decay chain and the rate for inclusive soft pion production at low transverse momentum with respect to the nearest jet. The result is B(D0 → K−π+0 = (3.90 ± 0.09 ± 0.12)%
A Measurement Of Rb Using A Lifetime-Mass Tag, R. Barate, Manoj Thulasidas
A Measurement Of Rb Using A Lifetime-Mass Tag, R. Barate, Manoj Thulasidas
Research Collection School Of Computing and Information Systems
ALEPH's published measurement of Rb = Γ(Ζ → bb̄)/Γ(Ζ → hadrons) using a lifetime tag is updated using the full LEP 1 data sample. Considerable effort has been devoted to understanding systematic effects. Charm background is better controlled by combining the lifetime tag with a tag based on the b/c hadron mass difference. Furthermore, the algorithm used to reconstruct the event primary vertex is designed so as to reduce correlations between the two hemispheres of an event. The value of Rb is measured to be 0.2167 ± 0.0011 (stat) ± 0.0013 (syst).
Source-Aware Multidatabase Query Processing, Ee Peng Lim, Yinyan Cao, Roger Hsiang-Li Chiang
Source-Aware Multidatabase Query Processing, Ee Peng Lim, Yinyan Cao, Roger Hsiang-Li Chiang
Research Collection School Of Computing and Information Systems
We introduce a multidatabase model to represent the information that derives from different local databases. This model, known as Tuple-Source (TS) relational model, accommodates tuples from different local databases by attaching them with their source information in the global relations which are also known as TS-relations. In other words, a source attribute is implicit in every TS-relation. To manipulate the global relations, we have developed the TSSQL query language and implemented a distributed query processor to process such queries. In this paper, we report our distributed query processing architecture and algorithms. Our architecture consists of a query mediator and a …
A Measurement Of Rb Using Mutually Exclusive Tags, R. Barate, Manoj Thulasidas
A Measurement Of Rb Using Mutually Exclusive Tags, R. Barate, Manoj Thulasidas
Research Collection School Of Computing and Information Systems
A measurement of Rb using ve mutually exclusive hemisphere tags has been performed by ALEPH using the full LEP1 statistics. Three tags are designed to select the decay of the Z0 to b quarks, while the remaining two select Z0 decays to c and light quarks, and are used to measure the tagging eciencies. The result, Rb = 0:2159 0:0009(stat) 0:0011(syst), is in agreement with the electroweak theory prediction of 0:21580:0003.
Study Of Muon-Pair Production At Centre-Of-Mass Energies From 20 To 136 Gev With The Aleph Detector, R. Barate, M. Thulasidas
Study Of Muon-Pair Production At Centre-Of-Mass Energies From 20 To 136 Gev With The Aleph Detector, R. Barate, M. Thulasidas
Research Collection School Of Computing and Information Systems
The total cross section and the forward-backward asymmetry for the process e+e− → μ+μ−(nγ) are measured in the energy range 20–136 GeV by reconstructing the effective centre-of-mass energy after initial state radiation. The analysis is based on the data recorded with the ALEPH detector at LEP between 1990 and 1995, corresponding to a total integrated luminosity of 143.5 pb−1. Two different approaches are used: in the first one an exclusive selection of events with hard initial state radiation in the energy range 20–88 GeV is directly compared with the Standard Model predictions showing good agreement. In the second one, all …
Distributed Query Processing For Structured And Bibliographic Databases, Ee Peng Lim, Ying Lu
Distributed Query Processing For Structured And Bibliographic Databases, Ee Peng Lim, Ying Lu
Research Collection School Of Computing and Information Systems
To support future digital library systems which draw information from different sources on the internet, we have to provide integrated queries to pre-existing database servers which contain structured, semi-structured and unstructured data. In this paper, we specifically examine the problem of querying both existing structured relational databases and bibliographic databases. By adopting the well-accepted Z39.50 standard protocol to access bibliographic databases in different legacy library systems, we have developed an extended SQL model, known as HarpSQL, to support integrated queries to both SQL databases and bibliographic databases. Using HarpSQL, one can not only query bibliographic databases in an SQL manner, …
A New On-Line Cash Check Scheme, Robert H. Deng, Yongfei Han, Albert B. Jeng, Teow-Hin Ngair
A New On-Line Cash Check Scheme, Robert H. Deng, Yongfei Han, Albert B. Jeng, Teow-Hin Ngair
Research Collection School Of Computing and Information Systems
This paper presents a new on-line cash check scheme which guarantees payor anonymity and improves upon existing similar schemes in efficiency and security.
Cascade Artmap: Integrating Neural Computation And Symbolic Knowledge Processing, Ah-Hwee Tan
Cascade Artmap: Integrating Neural Computation And Symbolic Knowledge Processing, Ah-Hwee Tan
Research Collection School Of Computing and Information Systems
This paper introduces a hybrid system termed cascade adaptive resonance theory mapping (ARTMAP) that incorporates symbolic knowledge into neural-network learning and recognition. Cascade ARTMAP, a generalization of fuzzy ARTMAP, represents intermediate attributes and rule cascades of rule-based knowledge explicitly and performs multistep inferencing. A rule insertion algorithm translates if-then symbolic rules into cascade ARTMAP architecture. Besides that initializing networks with prior knowledge can improve predictive accuracy and learning efficiency, the inserted symbolic knowledge can be refined and enhanced by the cascade ARTMAP learning algorithm. By preserving symbolic rule form during learning, the rules extracted from cascade ARTMAP can be compared …
Inductive Neural Logic Network And The Scm Algorithm, Ah-Hwee Tan, Loo-Nin Teow
Inductive Neural Logic Network And The Scm Algorithm, Ah-Hwee Tan, Loo-Nin Teow
Research Collection School Of Computing and Information Systems
Neural Logic Network (NLN) is a class of neural network models that performs both pattern processing and logical inferencing. This article presents a procedure for NLN to learn multi-dimensional mapping of both binary and analog data. The procedure, known as the Supervised Clustering and Matching (SCM) algorithm, provides a means of inferring inductive knowledge from databases. In contrast to gradient descent error correction methods, pattern mapping is learned by an inductive NLN using fast and incremental clustering of input and output patterns. In addition, learning/encoding only takes place when both the input and output match criteria are satisfied in a …
Studies Of Qcd In E+E- → Hadrons At Ecm = 130 And 136 Gev, D. Buskulic, M. Thulasidas
Studies Of Qcd In E+E- → Hadrons At Ecm = 130 And 136 Gev, D. Buskulic, M. Thulasidas
Research Collection School Of Computing and Information Systems
Studies of QCD in e+e−→e+e−→ Hadrons at Ecm=Ecm=} 130 and 136 GeV The ALEPH Collaboration An analysis of the properties of hadronic final states produced in electron-positron annihilation at centre-of-mass energies of 130 and 136 GeV is presented. The measurements are based on a data sample of 5.7 pb−1pb−1 collected in November 1995 with the \Aleph detector at LEP. Inclusive charged particle distributions, jet rates and event-shape distributions are measured and the results are compared with the predictions of QCD-based models. From the measured distributions quantities are determined for which the dependence on the centre-of-mass energy can be predicted by …
Low-Degree Graph Partitioning Via Local Search With Applications To Constraint Satisfaction, Max Cut, And Coloring, Magnus M. Halldorsson, Hoong Chuin Lau
Low-Degree Graph Partitioning Via Local Search With Applications To Constraint Satisfaction, Max Cut, And Coloring, Magnus M. Halldorsson, Hoong Chuin Lau
Research Collection School Of Computing and Information Systems
We present practical algorithms for constructing partitions of graphs into a fixed number of vertex-disjoint subgraphs that satisfy particular degree constraints. We use this in particular to find k-cuts of graphs of maximum degree ∆ that cut at least a k - 1/k (1 + 1/2∆+k-1 ) fraction of the edges, improving previous bounds known. The partitions also apply to constraint networks, for which we give a tight analysis of natural local search heuristics for the maximum constraint satisfaction problem. These partitions also imply efficient approximations for several problems on weighted bounded-degree graphs. In particular, we improve the best performance …
Report On The 5th Ifip International Workshop On Quality Of Service, Oguz Angin, Andrew T. Campbell, Lai Tee Cheok, Raymond Liao, Koon-Seng Lim, Klara Nahrstedt
Report On The 5th Ifip International Workshop On Quality Of Service, Oguz Angin, Andrew T. Campbell, Lai Tee Cheok, Raymond Liao, Koon-Seng Lim, Klara Nahrstedt
Research Collection School Of Computing and Information Systems
This paper presents a summary of the fifth International Workshop on Quality of Service (IWQOS) which was held at Columbia University in May 1997. The goal of this three-day meeting was to foster interaction between researchers active in the area of Quality of Service(QOS) research, to reflect on past experiences and lessons learnt, and to discuss future QOS challenges. To reflect this goal, this year's workshop included a hot program made up of (i) a keynote address on "Programming Telecommunications Networks"; (ii) panels addressing "QOS for Distributed Object Computing Middleware --- Fact or Fiction?" and "Reservations about Reservations"; (iii) a …
Transverse Momentum Correlations In Hadronic Z Decays, D. Buskulic, M. Thulasidas
Transverse Momentum Correlations In Hadronic Z Decays, D. Buskulic, M. Thulasidas
Research Collection School Of Computing and Information Systems
Using data obtained with the ALEPH detector at the Z resonance, a measure based on transverse momentum is shown to exhibit a correlation between the two halves of a hadronic event which cannot be explained by energy-momentum conservation, flavour conservation, the imposition of an event axis or imperfect event reconstruction. Two possible interpretations based on existing Monte Carlo models are examined: a) ARIADNE, with the correlation forming early in the parton shower and with the transition from partons to hadrons playing only a minor part; b) JETSET, with the correlation forming at the fragmentation stage. A correlation technique based on …
A Hypermedia Database To Manage World-Wide-Web Documents, Schubert Shou Boon Foo, Ee Peng Lim
A Hypermedia Database To Manage World-Wide-Web Documents, Schubert Shou Boon Foo, Ee Peng Lim
Research Collection School Of Computing and Information Systems
The surge of interest in the World-Wide-Web (WWW) with its potential commercial payoff has resulted in an explosion of information as organisations join in to publish and do business on the Internet. A related development, Intranet, which basically uses the same technology to build private corporate WWW-based networks, has emerged to provide cost-effective and efficient groupware and information management solutions for organisations. As a result, the Hyper Text Markup Language (HTML), used for constructing WWW documents, has become a contender for authoring future office documents. With this scenario, this study examines WWW practices and highlights the inadequacy and drawbacks of …
Measurement Of The Spectral Functions Of Vector Current Hadronic Tau Decays, R. Barate, M. Thulasidas
Measurement Of The Spectral Functions Of Vector Current Hadronic Tau Decays, R. Barate, M. Thulasidas
Research Collection School Of Computing and Information Systems
A measurement of the spectral functions of non-strange τ vector current final states is presented, using 124 358 τ pairs recorded by the ALEPH detector at LEP during the years 1991 to 1994. The spectral functions of the dominant two- and four-pion τ decay channels are compared to published results of e + e - annihilation experiments via isospin rotation. A combined fit of the pion form factor from τ decays and e + e - data is performed using different parametrizations. The mass and the width of the ρ ±(770) and the ρ 0(770) are separately determined in order …
The Topology Dependence Of Charged Particle Multiplicities In Three-Jet Events, R. Barate, M. Thulasidas
The Topology Dependence Of Charged Particle Multiplicities In Three-Jet Events, R. Barate, M. Thulasidas
Research Collection School Of Computing and Information Systems
A study of individual jet and whole-event charged particle multiplicities in three-jet events measured in e + e − annihilation at the Z reveals a significant topology dependence. Mean jet multiplicities are inadequately described by jet energies; interjet angles must also be specified. Quantitative tests suggest that it is necessary to use transversemomentum- like scales to describe the data.
Integrated Queries To Existing Bibliographic And Structured Databases, Ee Peng Lim, Ying Lu
Integrated Queries To Existing Bibliographic And Structured Databases, Ee Peng Lim, Ying Lu
Research Collection School Of Computing and Information Systems
It is widely accepted that future digital library applications have to be built upon different kinds of database servers to draw upon different forms of data, including bibliographic, text, multimedia, and structured data. In this paper, the problem of integrating existing public bibliographic databases and structured databases which reside at different locations in the network is addressed. Although bibliographic data is semistructured, its attribute set is often determined by an international standard known as MARC. To unify bibliographic and structured data, the well-known SQL was extended to model bibliographic related attributes and queries. In particular, a new data type was …
Managing World Wide Web Publications, Schubert Foo, Ee Peng Lim
Managing World Wide Web Publications, Schubert Foo, Ee Peng Lim
Research Collection School Of Computing and Information Systems
The surge of interest in the World Wide Web (WWW), with its potential commercial payoff, has resulted in an explosion of information as organizations join in the fray to publish and do business on the Internet. In addition, Intranet, the private corporate WWW‐based network, has also emerged to provide cost‐effective and efficient groupware and information management solutions for organizations. As a result, the HyperText Markup Language used for constructing WWW documents has become a contender for authoring future office documents. Examines the current practices of WWW publishing and highlights its inadequacies and drawbacks. Demonstrates the need and advantages of using …
Measurement Of The Τ Lepton Lifetime With The Three-Dimensional Impact Parameter Method, R. Barate, M. Thulasidas
Measurement Of The Τ Lepton Lifetime With The Three-Dimensional Impact Parameter Method, R. Barate, M. Thulasidas
Research Collection School Of Computing and Information Systems
A new method is presented for the measurement of the mean lepton lifetime using events in which are pair-produced and both's decay to hadrons.