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Observation Of Doubly-Charmed B Decays At Lep, R. Barate, M. Thulasidas Jan 1998

Observation Of Doubly-Charmed B Decays At Lep, R. Barate, M. Thulasidas

Research Collection School Of Computing and Information Systems

A search for doubly-charmed B decays with both charmed mesons reconstructed is performed, using about 3.8 million hadronic Z decays recorded with the ALEPH detector at LEP. A clear signal is observed in the channels B→DsD¯(X)B→DsD¯(X) and B→DD¯(X)B→DD¯(X) (where D can be either a D00, a D++ or a D∗+∗+), providing the first direct evidence for doubly-charmed B decays involving no DsDs production. Evidence for associated K0SKS0 and K±K± production in the decays B→DD¯(X)B→DD¯(X) is also presented and some candidates for completely reconstructed decays B→DsD¯(nπ)B→DsD¯(nπ), B→DD¯K0SB→DD¯KS0 and B→DD¯K±B→DD¯K± are observed. Furthermore, candidates for the two-body Cabibbo suppressed decays B0→D∗−D∗+B0→D∗−D∗+ and …


Searches For Charginos And Neutralinos In E+E- Collisions At √S = 161 And 172 Gev, R. Barate, M. Thulasidas Jan 1998

Searches For Charginos And Neutralinos In E+E- Collisions At √S = 161 And 172 Gev, R. Barate, M. Thulasidas

Research Collection School Of Computing and Information Systems

The data recorded by the ALEPH detector at centre-of-mass energies of 161, 170, and 172 GeV are analysed for signals of chargino and neutralino production. No evidence of a signal is found, although candidate events consistent with the expectations from Standard Model processes are observed. Limits at 95% C.L. on the production cross sections are derived and bounds on the parameters of the Minimal Supersymmetric Standard Model are set. The lower limit on the mass of the lightest ch is 85.5 GeV/c2GeV/c2 for gaugino-like charginos (μ=−500GeV/c2μ=−500GeV/c2), and 85.0 GeV/c2GeV/c2 for Higgsino-like charginos (M2=500GeV/c2M2=500GeV/c2), for heavy sneutrinos (Mν~≥200GeV/c2Mν~≥200GeV/c2) and tanβ=2–√tan⁡β=2. The …


Study Of B0s Oscillations And Lifetime Using Fully Reconstructed D̄S Decays, R. Barate, M. Thulasidas Jan 1998

Study Of B0s Oscillations And Lifetime Using Fully Reconstructed D̄S Decays, R. Barate, M. Thulasidas

Research Collection School Of Computing and Information Systems

A search for B0sBs0 oscillations is performed using approximately 4 million Z→qq¯Z→qq¯ events collected by the ALEPH experiment during 1991–1995. B0sBs0 candidates are partially reconstructed by combining tracks with fully reconstructed D−sDs− candidates. The B0sBs0 production flavour is estimated from the sign of the opposite hemisphere charge, a fragmentation kaon in the same hemisphere, or a lepton in the opposite hemisphere. From a total sample of 1620 candidates, with a B0sBs0 purity estimated to be 22%, all values of ΔmsΔms below 3.9 ps−1−1 and between 6.5 and 8.8 ps−1−1 are excluded at 95% CL. From the same sample, the B0sBs0 …


Market-Based Assets And Shareholder Value: A Framework For Analysis, Rajendra Kumar Srivastava, Tasadduq A. Shervani, Liam Fahey Jan 1998

Market-Based Assets And Shareholder Value: A Framework For Analysis, Rajendra Kumar Srivastava, Tasadduq A. Shervani, Liam Fahey

Research Collection Lee Kong Chian School Of Business

The authors develop a conceptual framework of the marketing-finance interface and discuss its implications for the theory and practice of marketing. The framework proposes that marketing is concerned with the task of developing and managing market-based assets, or assets that arise from the commingling of the firm with entities in its external environment. Examples of market-based assets include customer relationships, channel relationships, and partner relationships. Market-based assets, in turn, increase shareholder value by accelerating and enhancing cash flows, lowering the volatility and vulnerability of cash flows, and increasing the residual value of cash flows. ABSTRACT FROM AUTHOR Copyright of Journal …


Studies Of Quantum Chromodynamics With The Aleph Detector, R. Barate, M. Thulasidas Jan 1998

Studies Of Quantum Chromodynamics With The Aleph Detector, R. Barate, M. Thulasidas

Research Collection School Of Computing and Information Systems

No abstract provided.


Evaluation Of Information Modeling Methods: A Review, Keng Siau, Matti Rossi Jan 1998

Evaluation Of Information Modeling Methods: A Review, Keng Siau, Matti Rossi

Research Collection School Of Computing and Information Systems

Hundreds of modeling methods are in existence today. Yet practitioners and researchers are zealously "producing" new modeling methods. The "blooming" of modeling methods is not the problem; the lack of standardize techniques for evaluating them is. To further complicate the matter, most of the modeling methods are introduced based on common sense and intuition. Theoretical foundations and empirical evidence are severely lacking. With the current state of affairs, evaluation of modeling methods has become necessary. Comparing modeling methods provides us with the necessary knowledge and understanding on the strengths and weaknesses of each method. This knowledge can also guide us …


Measurement Of The Fraction Of Hadronic Z Decays Into Charm Quark Pairs, R. Barate, M. Thulasidas Jan 1998

Measurement Of The Fraction Of Hadronic Z Decays Into Charm Quark Pairs, R. Barate, M. Thulasidas

Research Collection School Of Computing and Information Systems

The full statistics of hadronic Z decays collected with the ALEPH detector are analysed to measure, by three methods, the ratio, RcRc, of the partial decay width of the Z into cc¯cc¯ quarks to the total hadronic width. One method uses the inclusive pp and p⊥p⊥ spectra of electrons. The other two use a double-tagging technique to measure RcRc independently of the charm-tagging efficiency. In one, the tagging procedure uses the reconstruction of high momentum charmed mesons (D∗+D∗+, D+D+ and \({\rm D^0}$) to detect the charm quarks. In the other, a charm quark is tagged from the D∗D∗'s reconstructed in …


Evaluating Information Modeling Methods – A Review, Keng Siau, M. Rossi Jan 1998

Evaluating Information Modeling Methods – A Review, Keng Siau, M. Rossi

Research Collection School Of Computing and Information Systems

Hundreds of modeling methods are in existence today, yet practitioners and researchers are zealously “producing” new modeling methods. The “blooming” of modeling methods is not the problem; the lack of standardized techniques for evaluating them is. To further complicate the matter, most of the modeling methods are introduced based on common sense and intuition. Theoretical foundations and empirical evidence are severely lacking. With the current state of affairs, evaluation of modeling methods has become necessary. Comparing modeling methods provides us with the necessary knowledge and understanding on the strengths and weaknesses of each method. This knowledge can also guide us …


Measurement Of The Axial-Vector Τ Spectral Functions And Determination Of Αs (M2Τ) From Hadronic Τ Decays, R. Barate, M. Thulasidas Jan 1998

Measurement Of The Axial-Vector Τ Spectral Functions And Determination Of Αs (M2Τ) From Hadronic Τ Decays, R. Barate, M. Thulasidas

Research Collection School Of Computing and Information Systems

An analysis based on 124 000 selected ττ pairs recorded by the ALEPH detector at LEP provides the vector (V)(V) and axial-vector (A)(A) spectral functions of hadronic ττ decays together with their total widths. This allows the evaluation of finite energy chiral sum rules that are weighted integrals over the (V−A)(V−A) spectral functions. In addition, a precise measurement of αsαs along with a determination of nonperturbative contributions at the ττ mass scale is performed. The experimentally and theoretically most robust determination of αs(M2τ)αs(Mτ2) is obtained from the (V+A)(V+A) fit that yields αs(M2τ)=0.334±0.022αs(Mτ2)=0.334±0.022 giving αs(M2Z)=0.1202±0.0027αs(MZ2)=0.1202±0.0027 after the extrapolation to the mass …


Search For Supersymmetry With A Dominant R-Parity Violating Llē Coupling In E+E- Collisions At Centre-Of-Mass Energies Of 130 Gev To 172 Gev, R. Barate, M. Thulasidas Jan 1998

Search For Supersymmetry With A Dominant R-Parity Violating Llē Coupling In E+E- Collisions At Centre-Of-Mass Energies Of 130 Gev To 172 Gev, R. Barate, M. Thulasidas

Research Collection School Of Computing and Information Systems

A search for pair-production of supersymmetric particles under the assumption that R-parity is violated via a dominant LLE¯LLE¯ coupling has been performed using the data collected by ALEPH at centre-of-mass energies of 130–172 GeV. The observed candidate events in the data are in agreement with the Standard Model expectation. This is translated into lower limits on the mass of charginos, neutralinos, sleptons, sneutrinos and squarks. For instance, charginos with masses less than 73 GeV/c2c2 and neutralinos with masses less than 23 GeV/c2c2 are excluded at 95% confidence level for any generation structure of the LLE¯LLE¯ coupling, and for neutralino, slepton …


An Interlibrary Loan System On The World Wide Web, Schubert Shou Boon Foo, Ee Peng Lim Jan 1998

An Interlibrary Loan System On The World Wide Web, Schubert Shou Boon Foo, Ee Peng Lim

Research Collection School Of Computing and Information Systems

Inter-Library Loan (ILL) service is one of the services provided by libraries that offers users a way to access library resources beyond their affiliated libraries. Additionally, it allows participating libraries to share and maximize their resources. This work examines the ILL process used by libraries in Singapore and proposes that the existing paper-based manual system be replaced by a Web-based ILL system. Such a Web-based system has been successfully designed and implemented at the Nanyang Technological University. The paper presents an overview of the system requirements and architecture, implementation details and demonstrates the feasibility and advantages of the new system.


An Integrated Web-Based Ill System For Singapore Libraries, Schubert Foo, Ee Peng Lim Jan 1998

An Integrated Web-Based Ill System For Singapore Libraries, Schubert Foo, Ee Peng Lim

Research Collection School Of Computing and Information Systems

The paper proposes an integrated Web-based inter-library loan (ILL) system to replace and enhance the existing manual-based ILL system used by Singapore libraries. It describes the system requirements that must be supported in order to make it a viable and acceptable solution to all participating libraries. Subsequently, it presents the client-server Web-based system architecture, database design and Java development platform that are used to implement the system. The new system exhibits a host of advantages over the manual system including the minimising of human resource by eliminating form-filling and other forms of paper work completely, improving the access and speed …


Inclusive Production Of Neutral Pions In Hadronic Z Decays, R. Barate, M. Thulasidas Dec 1997

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 …


The Effect Of Data Model, System And Task Characteristics On User Query Performance – An Empirical Study, Hock Chan, Keng Siau, Kwok-Kee Wei Dec 1997

The Effect Of Data Model, System And Task Characteristics On User Query Performance – An Empirical Study, Hock Chan, Keng Siau, Kwok-Kee Wei

Research Collection School Of Computing and Information Systems

With the proliferation of end-user computing and empowerment of end users in the organizations, the user-database interface is increasingly being recognized as an important research area. A user-database interface consists of two key components: the data model and the query language. Database management system designers can manipulate these two components to produce an effective database interface to maximize user task performance. However, in order to do this, the designers first need to know the effect of the two components on end users and the interaction effect of the two components. Despite the acknowledgment of user-database interface as a cornerstone in …


Curbing Urban Traffic Congestion In Singapore: A Comprehensive Review, Rex S. Toh, Sock-Yong Phang Dec 1997

Curbing Urban Traffic Congestion In Singapore: A Comprehensive Review, Rex S. Toh, Sock-Yong Phang

Research Collection School Of Economics

One of the most pervasive and frustrating of modern transportation problems is urban traffic congestion. Since 1975, Singapore has introduced a relentless series of traditional and experimental measures to slow down the growth of the motor vehicle population and to control its usage. While some of the measures have been somewhat successful, some of the problems were shifted or were substituted. The Area Licensing Scheme led to a shifting of the problem in time and place while the quota system has substituted uncertainty in quantity with uncertainty in price. Furthermore, the Preferential Additional Registration Fee system and the Quota System …


Tertiary Storage In Multimedia Systems: Staging Or Direct Access?, Hwee Hwa Pang Nov 1997

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 …


Searches For Scalar Top And Scalar Bottom Quarks At Lep2, Barate, R.; Et Al., M. Thulasidas Nov 1997

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 …


Updated Measurement Of The Τ Lepton Lifetime, R. Barate, Manoj Thulasidas Nov 1997

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.


Search For The Standard Model Higgs Boson In E+E- Collisions At √S = 161, 170 And 172 Gev, Barate, R.; Et Al., M. Thulasidas Oct 1997

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 Oct 1997

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 Sep 1997

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 Sep 1997

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 Aug 1997

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.


Using Expert Support And Its Explanation Facilities For Group Decision Making, Fiona Fui-Hoon Nah, Izak Benbasat Aug 1997

Using Expert Support And Its Explanation Facilities For Group Decision Making, Fiona Fui-Hoon Nah, Izak Benbasat

Research Collection School Of Computing and Information Systems

As information technology is increasingly used to support group work, it becomes desirable to identify the types of computer-based decision aids that are beneficial for supporting group decision making. In a review of the decision support literature, Benbasat, DeSanctis and Nault (1993) point out the lack of empirical research in examining the use of expert support for group decision making. In our review of the literature in this respect, we identified only one case study (Sviokla, 1989), which examined the processes involved in the pre- and post-use of an expert support system (ESS) called PlanPower by a group of financial …


Theoretical Foundation For Relationship Construct In Information Modeling – Relation Element Theory, Keng Siau Aug 1997

Theoretical Foundation For Relationship Construct In Information Modeling – Relation Element Theory, Keng Siau

Research Collection School Of Computing and Information Systems

Information modeling is a critical process in software development. One of the key constructs in information modeling is the relationship construct. Though commonly used, the relationship construct is poorly defined and lacks a strong theoretical foundation. The objectives of this research are to define and classify the various relationships based on a theory in linguistic known as the relation element theory. This paper describes the theory, relates the theory to the relationship construct, and discusses the implication of the theory on the relationship construct.


Influence And Consensus In Group Decision Making Environment, Fiona Fui-Hoon Nah, Byungcho Kim Aug 1997

Influence And Consensus In Group Decision Making Environment, Fiona Fui-Hoon Nah, Byungcho Kim

Research Collection School Of Computing and Information Systems

In this research, the effect of expert support on influence and consensus in group decision making is investigated. The results indicate that ESS support diminishes the group members' influence on the group judgment as well as the influence exerted by the most influential group member. On the other hand, explanations support provided by ESS increases consensus in group decision making.


Measurement Of The Transverse Spin Correlations In The Decay Z → Τ+Τ-, Barate, R.; Et Al., M. Thulasidas Jul 1997

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.


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 Jul 1997

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 …


Measurement Of The Branching Fraction For D0 → K-Π+, R. Barate, M. Thulasidas Jun 1997

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)%


Search For The Bc Meson In Hadronic Z Decays, R. Barate, Manoj Thulasidas Jun 1997

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+)