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Heavy flavor physics at the Tevatron

Description: We report on the status of top and b quark physics at the Fermilab Teva-tron collider. In particular, we summarize the knowledge obtained by CDF and D 6 O on the top quark mass and production cross-section. We also present some new interesting results obtained by CDF with the discovery of the Bc meson and a first low statistic measurement of sin(2{beta}) at an hadronic col-lider.
Date: November 1, 1998
Creator: Apollinari, G.
Partner: UNT Libraries Government Documents Department

Lepton-flavor mixing and K --> pi nu nu bar decays

Description: The impact of possible sources of lepton-flavor mixing on K {yields} {pi}{nu}{bar {nu}} decays is analyzed. At the one-loop level lepton-flavor mixing originated from non-diagonal lepton mass matrices cannot generate a CP-conserving K{sub L} {yields} {pi}{sup 0}{nu}{bar {nu}} amplitude. The rates of these modes are sensitive to leptonic flavor violation when there are at least two different leptonic mixing matrices. New interactions that violate both quark and lepton universalities could enhance the CP-conserving component of {Lambda}(K{sub L} {yields} {pi}{sup 0}{nu}{bar {nu}}) and have a substantial impact. Explicit examples of these effects in the context of supersymmetric models, with and without R-parity conservation, are discussed.
Date: November 26, 2003
Creator: Grossman, Yuval; Isidori, Gino & Murayama, Hitoshi
Partner: UNT Libraries Government Documents Department

Anti-B-B Mixing Constrains Topcolor-Assisted Technicolor

Description: We argue that extended technicolor augmented with topcolor requires that all mixing between the third and the first two quark generations resides in the mixing matrix of left-handed down quarks. Then, the anti-B_d--B_d mixing that occurs in topcolor models constrains the coloron and Z' boson masses to be greater than about 5 TeV. This implies fine tuning of the topcolor couplings to better than 1percent.
Date: December 6, 2000
Creator: Burdman, Gustavo; Lane, Kenneth & Rador, Tonguc
Partner: UNT Libraries Government Documents Department


Description: We review a class of dynamical models in which top condensation occurs at the weak scale, giving rise to the large top quark mass and other phenomena. This typically requires a color embedding, SU(3){sub c} {yields} SU(3){sub 1} x SU(3){sub 2}, ergo ``Topcolor.`` Topcolor suggests a novel route to technicolor models in which sequential quarks condense under the Topcolor interaction to break electroweak symmetries.
Date: November 1, 1996
Partner: UNT Libraries Government Documents Department

Scalar top study: Detector optimization

Description: A vertex detector concept of the Linear Collider Flavor Identification (LCFI) collaboration, which studies pixel detectors for heavy quark flavor identification, has been implemented in simulations for c-quark tagging in scalar top studies. The production and decay of scalar top quarks (stops) is particularly interesting for the development of the vertex detector as only two c-quarks and missing energy (from undetected neutralinos) are produced for light stops. Previous studies investigated the vertex detector design in scenarios with large mass differences between stop and neutralino, corresponding to large visible energy in the detector. In this study we investigate the tagging performance dependence on the vertex detector design in a scenario with small visible energy for the International Linear Collider (ILC).
Date: September 1, 2006
Creator: Milstene, C. & Sopczak, A.
Partner: UNT Libraries Government Documents Department

Searching for R-parity violation at run-II of the tevatron.

Description: The authors present an outlook for possible discovery of supersymmetry with broken R-parity at Run II of the Tevatron. They first present a review of the literature and an update of the experimental bounds. In turn they then discuss the following processes: (1) resonant slepton production followed by R{sub P} decay, (a) via LQD{sup c} and (b) via LLE{sup c}; (2) how to distinguish resonant slepton production from Z{prime} or W{prime} production; (3) resonant slepton production followed by the decay to neutralino LSP, which decays via LQD{sup c}; (4) resonant stop production followed by the decay to a chargino, which cascades to the neutralino LSP; (5) gluino pair production followed by the cascade decay to charm squarks which decay directly via L{sub 1}Q{sub 2}D{sub 1}{sup c}; (6) squark pair production followed by the cascade decay to the neutralino LSP which decays via L{sub 1}Q{sub 2}D{sub 1}{sup c}; (7) MSSM pair production followed by the cascade decay to the LSP which decays (a) via LLE{sup c}, (b) via LQD{sup c}, and (c) via U{sup c}D{sup c}D{sup c}, respectively; and (8) top quark and top squark decays in spontaneous R{sub P}.
Date: June 22, 1999
Creator: Allanach, B.; Banerjee, S.; Berger, E. L.; Chertok, M.; Diaz, M. A.; Dreiner, H. et al.
Partner: UNT Libraries Government Documents Department

Possible new class of dense white dwarfs

Description: If the strange quark matter hypothesis is true, then a new class of white dwarfs can exist whose nuclear material in their deep interiors can have a density as high as the neutron drip density, a few hundred times the density in maximum-mass white dwarfs and 4 {times} 10{sup 4} the density in dwarfs of typical mass, M {approximately} 0.6M{sub {circle_dot}}. Their masses fall in the approximate range 10{sup {minus}4} to 1M{sub {circle_dot}}. They are stable against acoustical modes of vibration. A strange quark core stabilizes these stars, which otherwise would have central densities that would place them in the unstable region of the sequence between white dwarfs and neutron stars.
Date: January 10, 1995
Creator: Glendenning, N.K.; Kettner, C. & Weber, F.
Partner: UNT Libraries Government Documents Department

Top Quark Mass Measurements from the Tevatron

Description: We review the measurements of the top quark mass by the CDF and D0 collaborations using Run I data in excess of 1.00 pb{sup -1}. The D0 collaboration has recently updated its measurement of the top quark mass in the lepton + jets channel. The world average of the top quark mass from the CDF and D0 measurements in the lepton + jets channel now stands at 175.6 {+-} 5.5 GeV/c{sup 2}.
Date: June 1, 1997
Creator: Raja, R. & Collaborations, CDF and D0
Partner: UNT Libraries Government Documents Department

Single top production and M{subscriptT Tbar}

Description: Single top production provides opportunities for studying the charged-current weak interaction of the top quark. The t{anti t} invariant mass spectrum M{sub t{anti t}} enables the search for non-standard model t{anti t} resonance states. These two topics have motivated new developments in top quark related analyses at Fermilab Tevatron. This presenta- tion reports the current single top and M{sub t{anti t}} analysis methods and the corresponding results from the collider Run I data collected by the CDF and D#31; experiment. We conclude with the prospects for these studies in the upcoming collider Run II.
Date: May 11, 1999
Creator: Liu, Yi-Cheng
Partner: UNT Libraries Government Documents Department

Search for Scalar Top at CDF

Description: We report results of three searches for scalar top quark. Two of the searches look for direct production of scalar top quark followed by the decay of the scalar quark to charm quark and neutralino or bottom and chargino. The third search looks for top quark decaying to scalar top and neutralino followed by the decay of scalar top to bottom quark and neutralino. We find no evidence for the presence of scalar top quark in any of the searches. Therefore, depending on the search we set limits on the production cross-section, BR(t {yields} {tilde t}{sub 1} + {tilde {chi}}{sup 0}{sub 1}), or m{sub {tilde t}} vs. m{sub {tilde {chi}}{sup 0}{sub 1}}.
Date: May 11, 1999
Creator: Holck, C.
Partner: UNT Libraries Government Documents Department

Asymmetric quarks in the proton

Description: Asymmetries in the quark momentum distributions in the proton reveal fundamental aspects of strong interaction physics. Differences between {anti u} and {anti d} quarks in the proton sea provide insight into the dynamics of the pion cloud around the nucleon and the nature of chiral symmetry breaking. Polarized flavor asymmetries allow the effects of pion clouds to be disentangled from those of antisymmetrization. Asymmetries between s and {anti s} quark distributions in the nucleon are also predicted from the chiral properties of QCD.
Date: June 1, 2000
Creator: Melnitchouk, W.
Partner: UNT Libraries Government Documents Department

Resolving exceptional configurations

Description: In lattice QCD with Wilson fermions, exceptional configurations arise in the quenched approximation at small quark mass. The origin of these large previously uncontrolled lattice artifacts is identified. A simple well-defined procedure (MQA) is presented which removes the artifacts while preserving the correct continuum limit.
Date: October 1, 1997
Creator: Bardeen, W.; Eichten, E.; Duncan, A. & Thacker, H.
Partner: UNT Libraries Government Documents Department

Top and higgs at the Tevatron: Measurements, searches, prospects

Description: In this paper we summarize the status of Top Quark Physics and of searches for the Standard Model Higgs at the Tevatron. Results from both the CDF and D0 experiments are discussed and the prospects for the upcoming Run 2, in the year 2000, are outlined. Much work has been performed on these topics and due to the nature of these proceedings only a brief explanation can be offered here. For more details the reader should turn to the excellent sources listed in the reference section.
Date: May 11, 1999
Creator: Konigsberg, J.
Partner: UNT Libraries Government Documents Department

Neural Networks for Analysis of Top Quark Production

Description: Neural networks (NNs) provide a powerful and flexible tool for selecting a signal from a larger background. The D0 collaboration has used them extensively in studying t{anti t} decays. NNs were essential to the measurement of the t{anti t} production cross section in the all-jets channel (t{anti t} {yields} b {anti b}qqqq), and were also used in the measurement of the mass of the top quark in the lepton+jets channel (t{anti t} {yields} b{anti b}l{nu}q{anti q}). This paper will describe two new applications of neural networks to top quark analysis: the search for single top quark production, and an effort to increase the sensitivity in the dilepton channel t{anti t} {yields} b{anti b}e{anti {mu}}{nu}{anti {nu}} beyond that achieved in the published analysis.
Date: August 4, 1999
Creator: al., B. Abbott et
Partner: UNT Libraries Government Documents Department

Measurement of the top quark mass

Description: This dissertation describes the measurement of the top quark mass m{sub t} using events recorded during a 125 pb{sup -1} exposure of the D0 detector to {radical}s=1.8 TeV {anti p}p collisions. Six events consistent with the hypothesis t{anti t} {yields} bW{sup +}, {anti b}W{sup -} {yields} b{anti l}{nu}, {anti b}l{anti {nu}} form the dilepton sample. The kinematics of such events may be reconstructed for any assumed mt, and the likelihood of each such solution evaluated. A measurement of m{sub t} based on these relative solution likelihoods gives m{sub t} = 169.9 {+-} 14.8 (stat.) {+-} 3. 8 (syst.) GeV/c{sup 2}. A 2C kinematic fit is performed on a sample of 77 events consistent with t{anti t} {yields} bW{sup +}, {anti b}W{sup -} {yields} b{anti l}{nu}, {anti b}q{anti q} , and this, in combination with an estimate on the likelihood that each event is top, yields m{sub t} = 173.3 {+-} 5.6 (stat.) {+-} 6.2 (syst.) GeV/c{sup 2} . A combination of these two measurements gives m{sub t} = 173.1 {+-} 5.2 (stat.) {+-} 5.7 (syst.) GeV/c{sup 2}.
Date: December 31, 1997
Creator: Varnes, E.W.
Partner: UNT Libraries Government Documents Department

Parton Distributions and Spin-Orbital Correlations

Description: In this talk, I summarize a recent study showing that the large-x parton distributions contain important information on the quark orbital angular momentum of nucleon. This contribution could explain the conflict between the experimental data and the theory predictions for the polarized quark distributions. Future experiments at JLab shall provide further test for our predictions.
Date: September 24, 2007
Creator: Yuan, Feng
Partner: UNT Libraries Government Documents Department

Bounding CKM Mixing with a Fourth Family

Description: CKM mixing between third family quarks and a possible fourth family is constrained by global fits to the precision electroweak data. The dominant constraint is from nondecoupling oblique corrections rather than the vertex correction to Z {yields} {bar b}b used in previous analyses. The possibility of large mixing suggested by some recent analyses of FCNC processes is excluded, but 3-4 mixing of the same order as the Cabbibo mixing of the first two families is allowed.
Date: April 22, 2009
Creator: Chanowitz, Michael S.
Partner: UNT Libraries Government Documents Department

Top quark mass from CDF

Description: We report on the most recent measurements of the top quark mass in three decay channels, performed by the CDF Collaboration at the Tevatron collider. We combine these results to obtain a mass value of 176.0 #6; 6.5 GeV/ c 2.
Date: March 2, 1999
Creator: Yao, W.-M.
Partner: UNT Libraries Government Documents Department

Transverse momentum and centrality dependence of high-ptnon-photonic electron suppression in Au+Au collisions at $\sqrt{s_{NN}}$= 200 GeV

Description: The STAR collaboration at RHIC reports measurements of theinclusive yield of non-photonic electrons, which arise dominantly fromsemi-leptonic decays of heavy flavor mesons, over a broad range oftransverse momenta (1.2<pt<10 gevc) in pp, dAu, and AuAucollisions at sqrt sNN = 200 GeV. The non-photonic electron yieldexhibits unexpectedly large suppression in central AuAu collisions athigh pt, suggesting substantial heavy quark energy loss at RHIC. Thecentrality and \pt dependences of the suppression provide constraints ontheoretical models of suppression.
Date: July 11, 2006
Creator: Abelev, B. I.; Adams, J.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D. et al.
Partner: UNT Libraries Government Documents Department

Measurement of the charged multiplicities of b, c and light quark events from Z{sup 0} decays

Description: Average charged multiplicities have been measured separately for {ital b, c} and light quark ({ital u, d, s}) events from Z{sup 0} decays at SLD. Impact parameters of charged tracks were used to select enriched samples of {ital b} and light quark events. We measured the charged multiplicities: {bar {ital n}}{sub {ital uds}} = 19.80 {+-} 0.09 ({ital stat}) {+-} 0.57 ({ital syst}), {bar {ital n}}{sub {ital c}} = 21.17 {+-} 0.44 ({ital stat}) {+-} 1.01 ({ital syst}) and {bar {ital n}}{sub {ital b}}{+-}23.14 {+-} 0.09 ({ital stat}) {+-} 1.03 ({ital syst}) (PRELIMINARY), from which we derived the differences between the total average charged multiplicities of {ital c} or {ital b} quark events and light quark events: {delta}{bar {ital n}}{sub {ital c}} = 1.37 {+-} 0.45 ({ital stat}) {+-} 0.86 ({ital syst}) and {delta}{bar {ital n}}{sub {ital b}} = 3.34 {+-} 0. 13 ({ital stat}) {+-} 0.77 ({ital syst}) (PRELIMINARY). We compared these measurements with those at lower center-of-mass energies and with QCD predictions.
Date: June 1995
Creator: The SLD Collaboration
Partner: UNT Libraries Government Documents Department

Z{sup 0} pole direct measurements of the parity violation parameters A{sub b} and A{sub c} at SLD

Description: This report presents three different techniques used at SLD to measure directly the parity violation parameters of Zb{bar b} and Zc{bar c} couplings from the left-right forward-backward asymmetries. The results have been obtained using 150,000 hadronic Z{sup 0} decays accumulated during the 1993-95 runs with high electron beam polarization.
Date: September 1, 1996
Creator: Mancinelli, G.
Partner: UNT Libraries Government Documents Department