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Wan Ahmad Tajuddin Wan Abdullah

Publications and source records attributed to Wan Ahmad Tajuddin Wan Abdullah.

13 recordsLinked to original sources

Beyong the Higgs

A Higgs-compatible boson has been observed at the LHC at CERN. We briefly review the role of the Higgs in particle physics and describe some of the current challenges in understanding the fundamental structure of the universe. Is there supersymmetry and is it instrumental in uniting gravity with the other three fundamental forces? What makes up dark matter and dark energy? We also report on the efforts in experimental particle physics by Malaysian collaborators to answer some of these questions.

physics.gen-ph↗

Charged Higgs boson contribution to $\barν_e-e$ scattering from low to ultrahigh energy in Higgs triplet model

We study the $\barν_e-e$ scattering from low to ultrahigh energy in the framework of Higgs Triplet Model (HTM). We add the contribution of charged Higgs boson exchange to the total cross section of the scattering. We obtain the upper bound $h_{ee}/M_{H^\pm}\lesssim2.8\times10^{-3}GeV^{-1}$ in this process from low energy experiment. We show that by using the upper bound obtained, the charged Higgs contribution can give enhancements to the total cross section with respect to the SM prediction up to 5.16% at $E\leq10^{14}$ eV and maximum at $s\approx M_{H^\pm}^2$ and would help to determine the feasibility experiments to discriminate between SM and HTM at current available facilities.

hep-ph↗

Looking for plausibility

In the interpretation of experimental data, one is actually looking for plausible explanations. We look for a measure of plausibility, with which we can compare different possible explanations, and which can be combined when there are different sets of data. This is contrasted to the conventional measure for probabilities as well as to the proposed measure of possibilities. We define what characteristics this measure of plausibility should have. In getting to the conception of this measure, we explore the relation of plausibility to abductive reasoning, and to Bayesian probabilities. We also compare with the Dempster-Schaefer theory of evidence, which also has its own definition for plausibility. Abduction can be associated with biconditionality in inference rules, and this provides a platform to relate to the Collins-Michalski theory of plausibility. Finally, using a formalism for wiring logic onto Hopfield neural networks, we ask if this is relevant in obtaining this measure.

cs.AI↗

Flatness of the Energy Landscape for Horn Clauses

The Little-Hopfield neural network programmed with Horn clauses is studied. We argue that the energy landscape of the system, corresponding to the inconsistency function for logical interpretations of the sets of Horn clauses, has minimal ruggedness. This is supported by computer simulations.

cond-mat.dis-nn↗

Logic Mining Using Neural Networks

Knowledge could be gained from experts, specialists in the area of interest, or it can be gained by induction from sets of data. Automatic induction of knowledge from data sets, usually stored in large databases, is called data mining. Data mining methods are important in the management of complex systems. There are many technologies available to data mining practitioners, including Artificial Neural Networks, Regression, and Decision Trees. Neural networks have been successfully applied in wide range of supervised and unsupervised learning applications. Neural network methods are not commonly used for data mining tasks, because they often produce incomprehensible models, and require long training times. One way in which the collective properties of a neural network may be used to implement a computational task is by way of the concept of energy minimization. The Hopfield network is well-known example of such an approach. The Hopfield network is useful as content addressable memory or an analog computer for solving combinatorial-type optimization problems. Wan Abdullah [1] proposed a method of doing logic programming on a Hopfield neural network. Optimization of logical inconsistency is carried out by the network after the connection strengths are defined from the logic program; the network relaxes to neural states corresponding to a valid interpretation. In this article, we describe how Hopfield network is able to induce logical rules from large database by using reverse analysis method: given the values of the connections of a network, we can hope to know what logical rules are entrenched in the database.

cs.LO↗

Logic Learning in Hopfield Networks

Synaptic weights for neurons in logic programming can be calculated either by using Hebbian learning or by Wan Abdullah's method. In other words, Hebbian learning for governing events corresponding to some respective program clauses is equivalent with learning using Wan Abdullah's method for the same respective program clauses. In this paper we will evaluate experimentally the equivalence between these two types of learning through computer simulations.

cs.LO↗

Jirim kuark - mikroskopi elektron attoskala ke atas proton

We review experiments colliding electrons(/positrons) on protons at high energies at HERA, focussing on the ZEUS experiment. We describe the ZEUS detector, including its data acquisition system, and look at a specific part, namely the electronic system for its calorimeter readout control, in more detail. Data analysis is described, and results pertaining the proton structure is given. It is found that the naive quark model cannot explain the results obtained at small fractional momentum, and this requires quantum chromodynamics. Also it is found that diffractive reactions, with large rapidity gaps, contribute substantially; efforts are being carried out to understand them.

hep-ex↗

Kinetic Economies

We study a minimalist kinetic model for economies. A system of agents with local trading rules display emergent demand behaviour. We examine the resulting wealth distribution to look for non-thermal behaviour. We compare and contrast this model with other similar models.

q-fin.GN↗

Mutual Support in Agent Networks

We construct a model of social behaviour through the dynamics of interacting agents. The agents undergo game-theoretic interactions where each agent can decide to lend support to particular other agents or otherwise, and agents are rewarded according to total support received. We analyse and carry out Monte Carlo simulations of such systems to uncover their evolutionary dynamics, and to explore their phase structure.

physics.soc-ph↗

Love before Sex

Much has been debated about the benefit of sexual over asexual reproduction in terms of evolutionary fitness. Here we focus on the advantage that may be brought about by the process of mating, where the choosing of mates contributes to the increase in fitness in a constructive way. We carry out computer simulations of such mating systems and investigate, on one hand, how mate phenotypes contribute to offspring fitness, and, on the other hand, how selection affects mate phenotypes. We discuss how helpful such a mechanism may be in determining trajectories on rugged energy landscapes leading to global optimum.

q-bio.PE↗

Emergence of heterogeneity in an agent-based model

We study an interacting agent model of a game-theoretical economy. The agents play a minority-subsequently-majority game and they learn, using backpropagation networks, to obtain higher payoffs. We study the relevance of heterogeneity to performance, and how heterogeneity emerges.

cond-mat↗

Learning strategies for global games with delayed payoffs

Economic ensembles can be modeled as networks of interacting agents whose be-haviors are described in terms of game theory. The evolutionary paradigm has been applied to two-person games to discover strategies in this context. Subse-quently, many-player games, and specifically global games (where payoffs depend collectively on all the rest of the players) as with the minimal game, have been studied. The minority game is attractive because it has intuitive similarities to e.g. securing niche businesses. We enhance this intuitive similarity by extending the game through the introduction of delayed payoffs. Payoffs depend on the values of future moves; we reward choices which later on become popular. We study agents' moves in such global game with delayed payoff. Instead of an evolutionary approach we allow learning in the agents. We study strategies that may emerge through learning in agents in such games.

cond-mat↗