Probing the Anomalous Couplings of the Top Quark with Gluon at the LHC and Tevatron

In this paper, we study the sensitivity of the fraction of $t\bar{t}$ events arising from gluon-gluon fusion to the chromoelectric and chromomagnetic dipole moments (CEDM and CMDM) as well as the total and differential $t\bar{t}$ cross sections at the LHC and Tevatron. The sensitivity of measured charged asymmetry at the LHC to CEDM and CMDM is also studied. We find that at the Tevatron and the LHC, non-zero values of CMDM could suppress the $t\bar{t}$ production rate. It is shown that the ratio of $\sigma(gg\rightarrow t\bar{t})/\sigma(p\bar{p}\rightarrow t\bar{t})$ at the Tevatron is more sensitive to CEDM and CMDM than the LHC case. The presence of CEDM always increases the contribution of gluon-gluon fusion process in top pair rate at the Tevatron and LHC. Except for a small range of CMDM, the presence of CEDM and CMDM can increase the fraction of gluon-gluon fusion at the Tevatron and LHC. The measured ratio of $\sigma(gg\rightarrow t\bar{t})/\sigma(p\bar{p}\rightarrow t\bar{t})$ at the Tevatron is used to derive bounds on the chromoelectric and chromomagnetic dipole moments as well as the total and differential ($d\sigma/dm_{t\bar{t}}$) cross sections at the LHC and Tevatron, and the measured charged asymmetry at the LHC. The combination of $d\sigma_{TeV}/dm_{t\bar{t}}$ and $\sigma_{LHC}$ provides stringent limits on CMDM and CEDM.Comment: 11 pages,6 figures,2 table

Probing the top quark chromoelectric and chromomagnetic dipole moments in single top tWtW-channel at the LHC

We study the effects of chromoelectric and chromomagnetic dipole moments (CEDM and CMDM) on the production cross section of single top $tW$-channel at the LHC based on the effective Lagrangian approach. We show that the impact of CEDM and CMDM could be large. Using the experimental measurement of the $tW$-channel cross section, constraints on CEDM and CMDM are extracted. These constraints are comparable with the ones obtained from the top pair analysis.Comment: 13 pages, 4 figure

Practicum in Biology I: Gastroenterology Site

Program Overview: Instructor - Dr. Mark Jaffe, DPM Didactic and experiential learning in applied settings Primary research literature exposure in field of interest Weekly face-to-face lectures for three hours Practicum site shifts for minimum 5 hours weekly Partnerships with Alvin Sherman Library and Career Services Departmen

Thermodynamic states of adsorbed hydrogen at noble-metal electrocatalysts in absence/presence of chemisorbed sulfur

The experimental and theoretical research on the hydrogen under-potential deposition (UPD) on Rh and Pt electrodes has led to determination of the Gibbs free energy ([delta]G[subscript ads]), the standard entropy ([delta]S[omicron][subscript ads]) and the standard enthalpy ([delta]H[omicron][subscript ads]) of adsorption based on a general adsorption isotherm rederived in the course of this work. The research has resulted in development of theoretical methodology allowing to evaluate, for the first time, the bond energy between the metal substrate, M, and the under-potential deposited H (H[subscript UPD]), E[subscript M]-[subscript H][subscript UPD] (here M = Pt or Rh). The impact of the specifically adsorbed anions on [delta]G[subscript ads], [delta]S[omicron][subscript ads] and [delta]H[omicron][subscript ads] has also been studied. Theoretical treatment of the experimental data based on the general electrochemical adsorption isotherm has allowed elucidation of [delta]G[subscript ads] as a function of the temperature, T, and the H surface coverage, [thêta][subscript H][subscript UPD]. The experimentally evaluated value of E[subscript M]-[subscript H][subscript UPD] is close to that of the bond energy between M and the chemisorbed H (H[subscript chem]). Proximity of the magnitude of E[subscript M]-[subscript H][subscript UPD] to that of E[subscript M]-[subscript H][subscript chem] (here M = Pt or Rh) points to the similar binding mechanism of H under the conditions involving presence of the electrified solid/liquid interface. Closeness of E[subscript M]-[subscript H][subscript UPD] to E[subscript M]-[subscript H][subscript chem] might also point to the same adsorption site of the two distinct H surface species, thus indicating that H[subscript UPD] alike H[subscript chem] is strongly embedded in the surface lattice of the Rh and Pt substrates. Temperature-dependent research on the UPD H and anion adsorption on Pt(111) and Pt(100) in 0.5 M aqueous H[subscript 2]SO[subscript 4] solution by cyclic-voltammetry, cv, conducted for the first time ever, indicates that the overall adsorption/desorption charge density is affected by temperature variation. An analysis of the [delta]G[subscript ads] (H [subscript UPD]) versus [thêta][subscript H][subscript UPD] plots reveal that the UPD H follows the Frumkin isotherm and the energy of lateral repulsions, [oméga], and the respective dimensionless parameter g are coverage independent. The value of E[subscript Pt(111)]-[subscript H][subscript UPD] is close to the surface bond energy between the chemisorbed H, H[subscript chem], and Pt(111), E[subscript Pt(111)]-[subscript H][subscript chem]. The influence of submonolayers of chemisorbed sulfur, S [subscript chem], on the UPD H on Pt(poly) and Pt(111) electrodes was studied. The research has demonstrated that a monolayer of S [subscript chem] on Pt can be formed by its immersion in aqueous Na[subscript 2]S solution. The S[subscript chem] can be gradually removed through oxidative desorption and its coverage can be controlled with the precision of some 1-2% of a mono layer. Theoretical treatment of the experimental results indicates that a submonolayer of S[subscript chem] having the nominal coverage of 0.10 increases the Gibbs free energy, the entropy and the enthalpy of adsorption for H[subscript UPD]. The bond energy between Pt and H[subscript UPD] decreases in presence of S[subscript chem] and the effect is brought about by local electron withdrawing effects that propagate through the underlying metal which acts as a mediator."--Résumé abrégé par UM

Electrogenerated Chemiluminescence of Gold Nanoclusters

A series of monodispersed AuNCs including Au144(SR)60, Au38(SR)24 and Au25(SR)18z (z =1-, 0 and 1+, SR=2-phenylethanethiol) were prepared. All these nanoclusters showed molecule-like optical and electrochemical properties. These two features are essential for an electrogenerated chemiluminescence or electrochemiluminescence (ECL) study. The Au144(SR)60 showed a small HOMO-LUMO gap determined by electrochemistry. No ECL light was seen in the annihilation process, while NIR ECL was observed with tri-n- propylamine (TPrA) (Chapter 2). ECL was highly efficient in the Au38(SR)24/TPrA co- reactant system. This nanocluster also showed ECL emission with benzoyl peroxide (BPO), while no ECL was detected in the annihilation route (Chapter 3). The ECL of Au25(SR)18z (z =1-, 0 and 1+) were discovered to emit NIR ECL light in the presence of either TPrA or BPO co-reactant. The Au25(SR)18+/ TPrA system revealed the strongest ECL emission among the three Au25 oxidation states (Chapter 4). The thermodynamic (Latimer-type diagram) and the kinetic origins of Au25(SR)180 ECL were explored in the presence of TPrA (Chapter 5). And lastly, the NIR ECL of Au25(SR)18− nanoclusters was mechanistically investigated in the presence of both TPrA and BPO with NIR emissions in both systems (Chapter 6). In each case a multiple ECL emissions were observed. The ECL peak wavelength and ECL intensity can be tuned by means of both the co-reactant concentration and applied electrode potential. It is worth noting that the Au38(SR)24 showed the strongest ECL efficiency among all the clusters studied, and the Au25(SR)18z clusters possessed a rich photoelectrochemistry leading to highly efficient ECL

A Bulk Driven Transimpedance CMOS Amplifier for SiPM Based Detection

The contribution of this work lies in the development of a bulk driven operationaltransconducctance amplifier which can be integrated with other analog circuits andphotodetectors in the same chip for compactness, miniaturization and reducing thepower. Silicon photomultipliers, also known as SiPMs, when coupled with scintillator materials are used in many imaging applications including nuclear detection. This thesis discuss the design of a bulk-driven transimpedance amplifier suitable for detectors where the front end is a SiPM. The amplifier was design and fabricated in a standard standard CMOS process and is suitable for integration with CMOS based SiPMs and commercially available SiPMs. Specifically, the amplifier was verified in simulations and experiment using circuit models for the SiPM. The bulk-driven amplifier’s performance, was compared to a commerciallyavailable amplifier with approximately the same open loop gain (70dB). Bothamplifiers were verified with two different light sources, a scintillator and a SiPM.The energy resolution using the bulk driven amplifier was 8.6% and was 14.2% forthe commercial amplifier indicating the suitability of the amplifier design for portable systems

Emergency Response Planning for Providing Drinking Water in Urban Areas after Natural Disasters using Multi Criteria Decision Making Methods

9 p.International audienceThe impact of a natural disaster can cause contamination of water, breaking pipelines, structural damages, water shortages, and collapse of the entire system. In emergency or disaster situations water supply are imperative for the rapid return to normalcy. In this paper, water supply planning for emergency response after natural disasters has been studied. Multi Criteria Decision Making (MCDM) has been used as a tool for incorporating decision maker preferences for water supply planning in emergency conditions. Analytical Hierarchy Process (AHP) as a well-known MCDM method was utilized for prioritizing water resources alternatives. For this purpose, the quality and quantity of water for living in emergency conditions after natural disasters were reviewed. Different water resources alternatives which are possible to use for emergency response were identified. Water resources availability, water quality, cost, affected population and delay in service were used as criteria for ranking the water resources alternatives. The proposed methodology was used for Pardis City in the vicinity of Tehran metropolitan in Iran, which is highly vulnerable to earthquakes and floods. The developed methodology provides an opportunity for further incorporation of decision makers' preferences in preparing an Emergency Response Plan (ERP) to improve respond to provide necessary water in disaster situation