We compute exactly the effective ZdF coupling in the Weinberg-Salam model in the limit of vanishing external momenta. The result is of importance if the effect of the t quark, which has presumably a rather large mass, is to be taken into account.

We compute the one-loop quark-diagram contribution to d h y y in the standard model as a function of m, where q = u , c , t , etc. We find it to be bounded, and such that the process K,+yy is likely to be dominated by low-energy contributions. We then use a phenomenological pole-dominance model to obtain

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A Wireless Sensor Network (WSN) is a network composed of many sensor nodes distributed in a region, and is used to monitor and gather information about certain phenomena in the physical IntroductionWireless Sensor Network (WSN) is widely used to observe and control certain environments, for various purposes such as emergency services, security and weather monitoring [1]. WSN includes single or multiple sensing elements, a data processor, communicating components and a power source with limited energy capacity [2], [3]. The sensing element, such as a sensor node, performs measurements related to its surrounding environment. The measurement data are processed in a processing unit and subsequently forwarded over a wireless channel to a base station, where they can be accessed by a user [3].One constraint of the use of WSN is the limited power of each sensor node, so energy consumption efficiency becomes an important issue in WSN. Routing is a function in WSN, which consumes a substantial amount of energy. Researches on network layer WSN systems aim to achieve an efficient route setup in terms of power, as well as allowing consistent data communication from sensor nodes to the base station [1]- [4]. Routing protocols developed for data communications network with the aim of achieving high Quality of Service (QoS) is generally not appropriate for WSN [3] due to the limitations of power source, storage capacity and data processing in the sensor nodes. Without specific routing protocols, with low energy consumption, the lifetime and WSN connectivity will be degraded. In LEACH, several nodes will be selected as a cluster head (CH). The number of CH nodes is proportional to the number of clusters. The node, which is selected as a CH node, will consume more energy than non-CH nodes [5][6][7][8][9][10]. Nodes that run out of energy will cease operating and the number of nodes in the system will be reduced. The purpose of this study is to evaluate the energy consumption of LEACH routing protocol for WSN systems and to find the optimum number of clusters. In order to obtain the minimum energy consumption, an evaluation was performed to identify the influence of the number of nodes on the optimum number of clusters. The simulation is performed using Network Simulator 2 (NS-2).

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