Browsing by Subject "form factor"
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Item Charmonium absorption and charmed hadron production in hadronic reactions(Texas A&M University, 2005-02-17) Liu, WeiA gauged SU(4) flavor symmetric hadronic Lagrangian with empirical hadron masses is constructed to study charmonium absorption and charmed hadron production in hadronic reactions. For the coupling constants, empirical values are used if available. Otherwise, they are determined from known coupling constants using the SU(4) relations. To take into account the finite sizes of hadrons, form factors are introduced at strong interaction vertices with empirical cutoff parameters. For J/ψabsorption by nucleons, we have included both two-and three-body final states and find that with a cutoff parameter of 1 GeV at interaction vertices involving charm hadrons, the cross section is at most 5 mb and is consistent with that extracted from J/ψproduction from both photo-and proton-nucleus reactions. We have also evaluated the cross sections for charmed hadron production from pion and rho meson interactions with nucleons. With the same cutoff parameter of 1 GeV at interaction vertices, we find that these cross sections have values of a few tenths of mb and are dominated bythe s-channel nucleon pole diagram. For charmed hadron production from proton-proton reactions, their cross sections including bothtwo-andthree-body final states are about 1 batcenter-of-mass energyof 11.5 GeV, which is comparable to the measured inclusive cross section in these reactions.Including photon as a U(1) gauge particle, we have extended the model to study charmed hadron production in photon-proton reactions with both two-and three-body final states included. For form factors, an overall one is introduced in each processin order to maintain the gauge invariance of the total amplitude. Fitting the cutoff parameter in the form factor to the measured total cross section for charmed hadron production in photon-proton reactions at a center-of-mass energy of 6 GeV, the ratio of the cross sections for two-body and three-body final states is consistent with available experimental data.This result is further compared with predictions from the leading-order perturbative QCD calculation. Knowledge of the cross sections for charmonium absorption byhadrons and for charmed hadron production in hadronic reactions is essential for understanding charm production in heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC), where a quark-gluon plasma is expected to be formed during the initial hot dense stage.Item Single Inductor Dual Output Buck Converter(2010-07-14) Eachempatti, HarithaThe portable electronics market is rapidly migrating towards more compact devices with multiple functionalities. Form factor, performance, cost and efficiency of these devices constitute the factors of merit of devices like cell phones, MP3 players and PDA's. With advancement in technology and more intelligent processors being used, there is a need for multiple high integrity voltage supplies for empowering the systems in portable electronic devices. Switched mode power supplies (SMPS's) are used to regulate the battery voltage. In an SMPS, maximum area is taken by the passive components such as the inductor and the capacitor. This work demonstrates a single inductor used in a buck converter with two output voltages from an input battery with voltage of value 3V. The main focus areas are low cross regulation between the outputs and supply of completely independent load current levels while maintaining desired values (1.2V,1.5V) within well controlled ripple levels. Dynamic hysteresis control is used for the single inductor dual output buck converter in this work. Results of schematic and post layout simulations performed in CADENCE prove the merits of this control method, such as nil cross regulation and excellent transient response.