Measurement of the Top-Quark Mass with Dilepton Events Selected Using Neuroevolution at CDF

We report a measurement of the top-quark mass Mt in the dilepton decay channel tt̄→bl′+νl′b̄l-ν̄l. Events are selected with a neural network which has been directly optimized for statistical precision in top-quark mass using neuroevolution, a technique modeled on biological evolution. The top-quark mass is extracted from per-event probability densities that are formed by the convolution of leading order matrix elements and detector resolution functions. The joint probability is the product of the probability densities from 344 candidate events in 2.0fb-1 of pp̄ collisions collected with the CDF II detector, yielding a measurement of Mt=171.2±2.7(stat)±2.9(syst)GeV/c2

CP violation in flavor-tagged Bs̳ --> J/[psi][phi] decays

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2009.In title on title page, [psi][phi] appears as lower case Greek letter italic and double underscored "s" appears as subscript. Cataloged from PDF version of thesis.Includes bibliographical references (p. 193-200).In this dissertation, we present the results of a time-dependent angular analysis of Bs -+ J/,0 decays performed with the use of initial-state flavor tagging. CP violation is observed in this mode through the interference of decay without net mixing and decay with net mixing, that is, Bs -- J/0 and Bs -+ B, -+ J/q0. The time-dependent angular analysis is used to extract the decay widths of the heavy and light B, eigenstates and the difference between these decay widths AF, - FL - FH. Initial-state flavor tagging is used to determine the matter-antimatter content of the B. mesons at production time. We combine flavor tagging with the angular analysis, which statistically determines the contributions of the CP-even and CP- odd components at decay time, to measure the CP-violating phase 0,. The phase 3, is expressed in terms of elements of the Cabibbo-Kobayashi-Maskawa matrix as s - arg (-VtsV4/VcsV*b), and is predicted by the Standard Model to be close to zero, O3SM = 0.02. In the measurement of AF,, we use a dataset corresponding to 1.7 fb- of luminosity, collected at the CDF experiment from proton-antiproton collisions at a center of mass energy f = 1.96 TeV. In the measurement of Ps, we use a dataset corresponding to 1.3 fb-1 of collected luminosity. We measure AF, = (0.071+0.064 ± 0.007) ps-1 using the time-dependent angular analysis. Combining the angular analysis with flavor-tagging, we find that assuming the Standard Model predictions of p/ and AF,, the probability of a deviation as large as the level of the observed data is 33%. We obtain a suite of associated results which are discussed in detail in this dissertation alongside the main results.by Khaldoun Makhoul.Ph.D

CP Violation in Flavor Tagged Bs→J/ψϕB_s \to J/\psi \phi Decays

In this dissertation, we present the results of a time-dependent angular analysis of B_s → J/ΨΦ decays performed with the use of initial-state flavor tagging. CP violation is observed in this mode through the interference of decay without net mixing and decay with net mixing, that is, B_s → J/ΨΦ and B_s → $\bar{B}$_s → J/ΨΦ . The time-dependent angular analysis is used to extract the decay widths of the heavy and light B_s eigenstates and the difference between these decay widths ΔΓ_s {triple_bond} Γ_s^L-Γ_s^H. Initial-state flavor tagging is used to determine the matter-antimatter content of the B_s mesons at production time. We combine flavor tagging with the angular analysis, which statistically determines the contributions of the CP-even and CP-odd components at decay time, to measure the CP-violating phase β_s. The phase β_s is expressed in terms of elements of the Cabibbo-Kobayashi-Maskawa matrix as β_s {triple_bond} arg (-V_tsV*_tb/V_csV*_cb), and is predicted by the Standard Model to be close to zero, β_s^SM = 0.02. In the measurement of ΔΓ_s, we use a dataset corresponding to 1.7 fb^-1 of luminosity, collected at the CDF experiment from proton-antiproton collisions at a center of mass energy √s = 1.96 TeV. In the measurement of β_s, we use a dataset corresponding to 1.3 fb^-1 of collected luminosity. We measure ΔΓ_s = (0.071_-0.059^+0.064 ± 0.007) ps^-1 using the time-dependent angular analysis. Combining the angular analysis with flavor-tagging, we find that assuming the Standard Model predictions of β_s and ΔΓ_s, the probability of a deviation as large as the level of the observed data is 33%. We obtain a suite of associated results which are discussed in detail in this dissertation alongside the main results

Cutaneous leishmaniasis: recognition and treatment.

Cutaneous leishmaniasis is a parasitic disease occurring throughout the Americas from Texas to Argentina, and in the Old World, particularly the Middle East and North Africa. It is spread by the female sandfly. The condition is diagnosed every year in travelers, immigrants, and military personnel. Physicians in the United States must be alert to the diagnosis of leishmaniasis in travelers returning from endemic areas. Physicians working for short periods in endemic areas often must make the diagnosis and should be aware of local disease patterns. When faced with a possible leishmanial skin lesion, a skin scraping with microscopic analysis is the best test. Punch biopsies with tissue-impression smears also can be diagnostic. Needle aspiration of tissue fluid from the margin of a lesion can yield fluid for culture to isolate the organism and identify the species. Immunologic tests are being developed, including a highly sensitive polymerase chain reaction test. The treatment mainstay is pentavalent antimony (e.g., sodium stibogluconate). Not all patients require treatment; many lesions heal spontaneously. Antimonials have a high incidence of reversible adverse effects. Other medications used for treatment include amphotericin B, pentamidine isethionate, paromomycin, and antifungals. This disease must be considered in at-risk patients, and family physicians should know the basics of diagnosis and where to go for more help

Search for a Heavy Toplike Quark in p p ¯ Collisions at √ s = 1.96 TeV

We present the results of a search for pair production of a heavy toplike (t ′) quark decaying to Wq final states using data corresponding to an integrated luminosity of 5.6fb -1 collected by the CDF II detector in pp̄ collisions at √s=1.96TeV. We perform parallel searches for t ′→Wb and t ′→Wq (where q is a generic down-type quark) in events containing a lepton and four or more jets. By performing a fit to the two-dimensional distribution of total transverse energy versus reconstructed t ′ quark mass, we set upper limits on the t ′t ̄′ production cross section and exclude a standard model fourth-generation t ′ quark decaying to Wb (Wq) with mass below 358 (340)GeV/c2 at 95% C.L. © 2011 American Physical Society

Search for anomalous production of events with two photons and additional energetic objects at CDF

We present results of a search for anomalous production of two photons together with an electron, muon, τ [tau] lepton, missing transverse energy, or jets using pp̅ collision data from 1.1–2.0  fb[superscript -1] of integrated luminosity collected by the Collider Detector at Fermilab (CDF). The event yields and kinematic distributions are examined for signs of new physics without favoring a specific model of new physics. The results are consistent with the standard model expectations. The search employs several new analysis techniques that significantly reduce instrumental backgrounds in channels with an electron and missing transverse energy.United States. Dept. of EnergyNational Science Foundation (U.S.)Istituto nazionale di fisica nucleareJapan. Ministry of Education, Culture, Sports, Science and TechnologyNatural Sciences and Engineering Research Council of CanadaNational Science Council (China)Swiss National Science FoundationAlfred P. Sloan FoundationGermany. Bundesministerium für Bildung und ForschungWorld Class University Program (Korea)National Research Foundation of KoreaScience and Technology Facilities Council (Great Britain)Royal Society (Great Britain)Institut national de physique nucléaire et de physique des particulesRussian Foundation for Basic ResearchSpain. Ministerio de Ciencia e Innovación (MICINN)Programa Consolider-Ingenio 2010, SpainSlovak R&D AgencyAcademy of Finlan

Measurement of the Λ[superscript 0][subscript b] Lifetime in Λ[superscript 0][subscript b] → Λ[superscript +][subscript c]π[subscript −] Decays in p[¯ over p] Collisions at √s = 1.96 TeV

We report a measurement of the lifetime of the Λ[superscript 0][subscript b] baryon in decays to the Λ[superscript +][superscript c]π[superscript −] final state in a sample corresponding to 1.1 fb[superscript −1] collected in p[¯ over p] collisions at √s=1.96 TeV by the CDF II detector at the Tevatron collider. Using a sample of about 3000 fully reconstructed Λ[superscript 0][subscript b] events we measure τ(Λ[superscript 0][subscript b]) =1.401±0.046(stat)±0.035(syst) ps (corresponding to cτ(Λ[superscript 0][subscript b])=420.1±13.7(stat)±10.6(syst) μm, where c is the speed of light). The ratio of this result and the world average B[superscript 0] lifetime yields τ(Λ[superscript 0][subscript b])/τ(B[superscript 0])=0.918±0.038 (stat) and (syst), in good agreement with recent theoretical predictions. © 2010 American Physical SocietyNational Science Foundation (U.S.)United States. Department of Energ

Direct Top-Quark Width Measurement at CDF

We present a measurement of the top-quark width in the lepton+jets decay channel of tt̅ events produced in pp̅ collisions at Fermilab’s Tevatron collider and collected by the CDF II detector. From a data sample corresponding to 4.3  fb-1 [fb superscript -1] of integrated luminosity, we identify 756 candidate events. The top-quark mass and the mass of the hadronically decaying W boson that comes from the top-quark decay are reconstructed for each event and compared with templates of different top-quark widths (Γt) [gamma subscript t] and deviations from nominal jet energy scale (ΔJES)[delta subscript JES] to perform a simultaneous fit for both parameters, where ΔJES [delta subscript JES] is used for the in situ calibration of the jet energy scale. By applying a Feldman-Cousins approach, we establish an upper limit at 95% confidence level (CL) of Γt<7.6  GeV [gamma subscript t<7.6 GeV] and a two-sided 68% CL interval of 0.3  GeV<Γt<4.4  GeV [GeV<gamma subscript t<4.4 GeV]] for a top-quark mass of 172.5  GeV/c2 [GeV / c superscript 2], which are consistent with the standard model prediction.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio

Measurements of branching fraction ratios and CP-asymmetries in suppressed B-→D(→K+π-)K- and B-→D(→K+π-)π- decays

We report the first reconstruction in hadron collisions of the suppressed decays B[superscript -]→D(→K[superscript +]π[superscript -])K[superscript -] and B-→D(→K[superscript +]π[superscript -])π[superscript -], sensitive to the Cabibbo-Kobayashi-Maskawa phase γ, using data from 7  fb[superscript -1] of integrated luminosity collected by the CDF II detector at the Tevatron collider. We reconstruct a signal for the B[superscript -]→D(→K[superscript +]π[superscript -])K[superscript -] suppressed mode with a significance of 3.2 standard deviations, and measure the ratios of the suppressed to favored branching fractions R(K)=[22.0±8.6(stat)±2.6(syst)]×10[superscript -3], R[superscript +](K)=[42.6±13.7(stat)±2.8(syst)]×10[superscript -3], R[superscript -](K)=[3.8±10.3(stat)±2.7(syst)]×10[superscript -3] as well as the direct CP-violating asymmetry A(K)=-0.82±0.44(stat)±0.09(syst) of this mode. Corresponding quantities for B-→D(→K[superscript +]π[superscript -])π[superscript -] decay are also reported.National Science Foundation (U.S.)United States. Dept. of EnergyAlfred P. Sloan Foundatio

Studying the underlying event in Drell-Yan and high transverse momentum jet production at the Tevatron

We study the underlying event in proton-antiproton collisions by examining the behavior of charged particles produced in association with a large transverse momentum jet (~2.2  fb[superscript -1]) or with a Drell-Yan lepton pair (~2.7  fb[superscript -1]) in the Z-boson mass region [70<M(pair)<110  GeV/c[superscript 2]] as measured by CDF at 1.96 TeV center-of-mass energy. We use the direction of the lepton pair or the leading jet in each event to define regions of η[eta]-ϕ[phi] space that are sensitive to the modeling of the underlying event. The data are corrected to the particle level to remove detector effects and are then compared with several QCD Monte Carlo models.United States. Dept. of EnergyNational Science Foundation (U.S.)Istituto nazionale di fisica nucleareJapan. Ministry of Education, Culture, Sports, Science and TechnologyNatural Sciences and Engineering Research Council of CanadaNational Science Council (China)Swiss National Science FoundationAlfred P. Sloan FoundationGermany. Bundesministerium für Bildung und ForschungNational Research Foundation of KoreaKorean Science and Engineering FoundationScience and Technology Facilities Council (Great Britain)Royal Society (Great Britain)Institut national de physique nucléaire et de physique des particulesRussian Foundation for Basic ResearchSpain. Ministerio de Ciencia e Innovación (MICINN)Slovak R&D AgencyAcademy of Finlan