Download or read book A Limit on the Branching Ratio of the Flavor changing Top Quark Decay T right Pointing Arrow ZC written by Alexander A. Paramonov and published by . This book was released on 2009 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Limit on the Branching Ratio of the Flavor Changing Top Quark Decay T u2192 Zc written by and published by . This book was released on 2009 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have used the Collider Detector at Fermilab (CDF-II) to set upper limits on the branching ratio of the flavor-changing neutral-current (FCNC) top quark decay t → Zc using a technique employing ratios of W and Z production, measured in 1.52 fb-1 of p$ar{p}$ data. The analysis uses a comparison of two decay chains, p$ar{p}$ → t$ar{t}$ → WbWb → lvbjjb and p$ar{p}$ → t$ar{t}$ ZcWb → l+l- cjjb, to cancel systematic uncertainties in acceptance, efficiency, and luminosity. We validate the MC modeling of acceptance and efficiency for lepton identification over the multi-year dataset also using a ratio of W and Z production, in this case the observed ratio of inclusive production of W to Z-bosons, a technique that will be essential for precision comparisons with the standard model at the LHC. We introduce several methods of determining backgrounds to the W and Z samples. To improve the discrimination against SM backgrounds to top quark decays, we calculate the top mass for each event with two leptons and four jets assuming it is a t$ar{t}$ event with one of the top quarks decaying to Zc. The upper limit on the Br(t → Zc) is estimated from a likelihood constructed with the l+l- cjjb top mass distribution and the number of lvbjjb events. Limits are set as a function of the helicity of the Z-boson produced in the FCNC decay. For 100%-longitudinally-polarized Z-bosons we find a limit of 8.3% (95% C.L.).
Download or read book A Limit on the Branching Ratio of the Flavor Changing Top Quark Decay T Zc written by and published by . This book was released on 2009 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have used the Collider Detector at Fermilab (CDF-II) to set upper limits on the branching ratio of the flavor-changing neutral-current (FCNC) top quark decay t 2!Zc using a technique employing ratios of W and Z production, measured in 1.52 fb−1 of p{bar p} data. The analysis uses a comparison of two decay chains, p{bar p} 2!t{bar t} 2!WbWb 2!l[nu]bjjb and p{bar p} 2!t{bar t} ZcWb 2!ll− cjjb, to cancel systematic uncertainties in acceptance, efficiency, and luminosity. We validate the MC modeling of acceptance and efficiency for lepton identification over the multi-year dataset also using a ratio of W and Z production, in this case the observed ratio of inclusive production of W to Z-bosons, a technique that will be essential for precision comparisons with the standard model at the LHC. We introduce several methods of determining backgrounds to the W and Z samples. To improve the discrimination against SM backgrounds to top quark decays, we calculate the top mass for each event with two leptons and four jets assuming it is a t{bar t} event with one of the top quarks decaying to Zc. The upper limit on the Br(t 2!Zc) is estimated from a likelihood constructed with the ll− cjjb top mass distribution and the number of l[nu]bjjb events. Limits are set as a function of the helicity of the Z-boson produced in the FCNC decay. For 100%-longitudinally-polarized Z-bosons we find a limit of 8.3% (95% C.L.).
Download or read book Search for the Neutral Current Top Quark Decay T Zc Using Ratio of Z Boson 4 Jets to W Boson 4 Jets Production written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We have used the Collider Detector at Fermilab (CDF II) to search for the flavor-changing neutral-current (FCNC) top quark decay t → Zc using a technique employing ratios of W and Z production, measured in p{bar p} data corresponding to an integrated luminosity of 1.52 fb−1. The analysis uses a comparison of two decay chains, p{bar p} → t{bar t} → WbWb → l[nu]bjjb and p{bar p} → t{bar t} → ZcWb → llcjjb, to cancel systematic uncertainties in acceptance, efficiency, and luminosity. We validate the modeling of acceptance and efficiency for lepton identification over the multi-year dataset using another ratio of W and Z production, in this case the observed ratio of inclusive production of W to Z bosons. To improve the discrimination against standard model backgrounds to top quark decays, we calculate the top quark mass for each event with two leptons and four jets assuming it is a t{bar t} event with one of the top quarks decaying to Zc. For additional background discrimination we require at least one jet to be identified as originating from a b-quark. No significant signal is found and we set an upper limit on the FCNC branching ratio Br(t → Zc) using a likelihood constructed from the llcjjb top quark mass distribution and the number of l[nu]bjjb events. Limits are set as a function of the helicity of the Z boson produced in the FCNC decay. For 100% longitudinally polarized Z bosons we find limits of 8.3% and 9.3% (95% C.L.) depending on the assumptions regarding the theoretical top quark pair production cross-section.
Download or read book Search for Flavor Changing Neutral Currents in Top Quark Decays Using a Two leptons track Selection written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Verslag en aanbevelings van die komitee van ondersoek na moontlike verdere fasiliteite vir geneeskundige en tandheelkundige opleiding written by and published by . This book was released on 1984 with total page 195 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Search for the Flavor Changing Neutral Current Decay t rightarrow QZ in p overline p Collisions at sqrt s written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation presents a blind search for the flavor changing neutral current decay of the top quark t → qZ in pp collisions at [special characters omitted] = 1.96TeV using a data sample corresponding to an integrated luminosity of 1.12 fb-1 collected by the Collider Detector at Fermilab (CDF), This decay is extremely rare in the standard model, and a signal at the Tevatron would be an indication of new physics. Dividing candidate events with a Z boson and four or more jets into a sample of those which have a heavy flavor jet identified by a secondary vertex algorithm and those which do not, we observe data yields consistent with background expectations. We set a 95% C.L. upper limit on the branching fraction B (t → qZ) of 11.3%, consistent with an expected upper limit of 7.8% ± 3.3%.
Download or read book Search for the Neutral Current Top Quark Decay T Zc Using the Ratio of Z boson 4 Jets to W boson 4 Jets Production written by and published by . This book was released on 2009 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Top Quark Properties from Top Pair Events and Decays written by and published by . This book was released on 2008 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over a decade since the discovery of the top quark we are still trying to unravel mysteries of the heaviest observed particle and learn more about its nature. The continuously accumulating statistics of CDF and DO data provide the means for measuring top quark properties with ever greater precision and the opportunity to search for signs of new physics that could be manifested through subtle deviations from the standard model in the production and decays of top quarks. In the following we present a slice of the rich program in top quark physics at the Fermilab Tevatron: measurements of the properties of top quark decays and searches for unusual phenomena in events with pair produced tops. In particular, we discuss the most recent and precise CDF and DO measurements of the transverse polarization of W bosons from top decays, branching ratios and searches for flavor-changing neutral current decays, decays into charged Higgs and invisible decays. These analyses correspond to integrated luminosities ranging from 0.9 to 2.7 fb−1.
Download or read book Search for Flavor changing Neutral Current Top Quark Decays T Hq with H Bb in Pp Collisions at square Root Of 2 written by Shota Tsiskaridze and published by . This book was released on 2015 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book B K Decays and Novel Flavor Factories written by David Cline and published by American Institute of Physics. This book was released on 1992 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: From a February 1991 conference in Santa Monica, California, 22 papers by particle, theoretical, and accelerator physicists discuss flavor physics and novel flavor factories (aspects of the subatomic world). CP violation and the search for flavor-changing weak neutral currents are covered extensivel
Download or read book Flavor Changing Neutral Currents in Ttbar Decays at D O written by and published by . This book was released on 2011 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a search for flavor changing neutral currents (FCNC) in decays of top quarks. The analysis is based on a search for t{bar t} → l'[nu]l{bar l} + jets (l,{ell}' = e, [mu]) final states using 4.1 fb−1 of integrated luminosity of p{bar p} collisions at √ s = 1.96 TeV. We extract limits on the branching ratio B(t → Zq) (q = u, c quarks), assuming anomalous tuZ or tcZ couplings. We do not observe any sign of such anomalous coupling and set a limit of B
Download or read book Up Sector of Minimal Flavor Violation written by and published by . This book was released on 2013 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Probing the Flavor Changing Vertex of the Top quark written by and published by . This book was released on 1991 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Probing the Flavor Changing Vertex of the Top quark written by and published by . This book was released on 1991 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: The implications of the flavor changing neutral current vertex, t 2!cX, where X = [gamma], g, Z, or H is examined in the Standard and two-Higgs-doublet models. 9 refs., 3 figs.
Download or read book Top Quark Mass Spectrum from Flavor changing Processes written by and published by . This book was released on 1990 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: The input from flavor-changing processes is reviewed and results of several analyses are presented on the top quark mass spectrum without recourse to the neutral-current data. A top quark mass in the range 135 {plus minus} 25 GeV is much preferred, but a very massive top quark above 300 GeV can not be ruled out. Comments are made about the future use of the inclusive decay B → [gamma] + X{sub S=1} for constraining the top quark mass. 24 refs., 2 figs.
Download or read book Dark Decay of Top Quark written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We suggest top quark decays as a venue to search for light dark force carriers. Top quark is the heaviest particle in the standard model whose decays are relatively poorly measured, allowing sufficient room for exotic decay modes from new physics. A very light (GeV scale) dark gauge boson (Z') is a recently highlighted hypothetical particle that can address some astrophysical anomalies as well as the 3.6 [sigma] deviation in the muon g-2 measurement. We present and study a possible scenario that top quark decays as t → b W + Z's. This is the same as the dominant top quark decay (t → b W) accompanied by one or multiple dark force carriers. The Z' can be easily boosted, and it can decay into highly collimated leptons (lepton-jet) with large branching ratio. We discuss the implications for the Large Hadron Collider experiments including the analysis based on the lepton-jets.
