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Multiple Valley Couplings in Nanometer Si MOSFETs

Description: We investigate the couplings between different energy band valleys in a MOSFET device using self-consistent calculations of million-atom Schroedinger-Poisson Equations. Atomistic empirical pseudopotentials are used to describe the device Hamiltonian and the underlying bulk band structure. The MOSFET device is under nonequilibrium condition with a source-drain bias up to 2V, and a gate potential close to the threshold potential. We find that all the intervalley couplings are small, with the coupling constants less than 3 meV. As a result, the system eigenstates derived from different bulk valleys can be calculated separately. This will significantly reduce the simulation time, because the diagonalization of the Hamiltonian matrix scales as the third power of the total number of basis functions.
Date: July 11, 2008
Creator: Wang, Lin-Wang; Deng, Hui-Xiong; Jiang, Xiang-Wei; Luo, Jun-Wei; Li, Shu-Shen; Xia, Jian-Bai et al.
Partner: UNT Libraries Government Documents Department

Reynolds stress of localized toroidal modes

Description: An investigation of the 2D toroidal eigenmode problem reveals the possibility of a new consistent 2D structure, the dissipative BM-II mode. In contrast to the conventional ballooning mode, the new mode is poloidally localized at {pi}/2 (or -{pi}/2), and possesses significant radial asymmetry. The radial asymmetry, in turn, allows the dissipative BM-II to generate considerably larger Reynolds stress as compared to the standard slab drift type modes. It is also shown that a wide class of localized dissipative toroidal modes are likely to be of the dissipative BM-II nature, suggesting that at the tokamak edge, the fluctuation generated Reynolds stress (a possible source of poloidal flow) can be significant.
Date: February 1, 1995
Creator: Zhang, Y.Z. & Mahajan, S.M.
Partner: UNT Libraries Government Documents Department

Heavy flavor lifetimes and lifetime differences

Description: The authors give an overview of heavy flavour lifetime measurements, focusing on recent results from the Tevatron and the B factories. In the first part of this article we summarize the status and latest measurements of B-hadron lifetimes and lifetime ratios, including some recent result from the Tevatron and the B factories, and compare those results with the predictions from Heavy Quark Expansion (HQE). Future prospects for lifetime measurements at the B factories and the Tevatron are discussed. In the second part, we review the status and prospects of measuring the difference between the lifetimes of the two CP eigenstates in the B{sub s}{sup 0}-{bar B}{sub s}{sup 0} system.
Date: September 17, 2003
Creator: Rademacker, Jonas
Partner: UNT Libraries Government Documents Department

On the mass eigenstate purity of Boron-8 solar neutrinos

Description: We give a brief report on our recent paper, Ref. [1], in which we calculate the {nu}{sub 2} mass eigenstate purity of {sup 8}B solar neutrinos as 91 {+-} 2%.
Date: January 1, 2006
Creator: Parke, Stephen J.; /Fermilab; Nunokawa, Hiroshi; /Rio de Janeiro, Pont. U. Catol.; Zukanovich Funchal, Renata & U., /Sao Paulo
Partner: UNT Libraries Government Documents Department

CP-conserving and CP-violating properties in semileptonic Bs decays with the D0 experiment

Description: A search for CP violation has been performed in a sample of semileptonic B{sub s} decays corresponding to approximately 5 fb{sup -1} of data collected by the D0 detector in Run II at the Fermilab Tevatron collider. A time-dependent fit to the distributions of B{sub s} candidates yields the flavor-specific asymmetry as a{sub fs}{sup s} = [-1.7 {+-} 9.1(stat){sub -2.3}{sup +1.2}(syst)] x 10{sup -3}, corresponding to the most precise measurement to date for this CP violation parameter. Furthermore a search for the semi-inclusive process B{sub s} to D{sub s}{sup (*)}D{sub s}{sup (*)} has been performed on a data sample of 2.8 fb{sup -1}. 26.6 {+-} 8.4 signal events are observed with a significance of 3.2 standard deviations above background, leading to a branching ratio of 0.035 {+-} 0.010(stat) {+-} 0.011(syst). Under certain theoretical assumptions, these double-charm final states saturate CP-even eigenstates in the B{sub s} decays, resulting in a width difference of {Delta}{Lambda}{sub s}{sup CP}/{Lambda}{sub s} = 0.072 {+-} 0.021(stat) {+-} 0.022(syst).
Date: August 1, 2009
Creator: Sonnenschein, Lars
Partner: UNT Libraries Government Documents Department

Measurement of the Time-dependent CP Asymmetry inB to D(*)_CP h0 Decays

Description: The authors report a measurement of the time-dependent CP-asymmetry parameters S and C in color-suppressed B{sup 0} {yields} D{sup (*)0}h{sup 0} decays, where h{sup 0} is a {pi}{sup 0}, {eta}, or {omega} meson, and the D{sup 0} decays to one of the CP eigenstates K{sup +}K{sup -}, K{sub S}{sup 0}{pi}{sup 0}, or K{sub S}{sup 0}{omega}. The data sample consists of 383 x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEP-II asymmetric-energy B-factory at SLAC. The results are S = -0.56 {+-} 0.23 {+-} 0.05 and C = -0.23 {+-} 0.16 {+-} 0.04, where the first error is statistical and the second is systematic.
Date: March 14, 2007
Creator: Aubert, B.
Partner: UNT Libraries Government Documents Department

Improved Measurement of CP Observables in B- to D0_CP K- Decays

Description: We present a study of the decay B{sup -} {yields} D{sub (CP)}{sup 0}K{sup -} and its charge conjugate, where D{sub (CP)}{sup 0} is reconstructed in both a non-CP flavor eigenstate and in CP (CP-even and CP-odd) eigenstates, based on a sample of 382 million {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEP-II e{sup +}e{sup -} storage ring. We measure the direct CP asymmetries A{sub CP{+-}} and the ratios of the branching fractions R{sub CP{+-}}: A{sub CP+} = 0.27 {+-} 0.09(stat) {+-} 0.04(syst), A{sub CP-} = -0.09 {+-} 0.09(stat) {+-} 0.02(syst), R{sub CP+} = 1.06 {+-} 0.10(stat) {+-} 0.05(syst), R{sub CP-} = 1.03 {+-} 0.10(stat) {+-} 0.05(syst). These results will help to better constrain the gamma phase parameter of the Cabibbo-Kobayashi-Maskawa quark mixing matrix.
Date: July 1, 2008
Creator: Aubert, Bernard; Bona, Marcella; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E. et al.
Partner: UNT Libraries Government Documents Department

Simplified Unitarity Triangles for the Lepton Sector

Description: Encouraged by the latest SNO results, we consider the lepton mixing matrix in the approximation that the {nu}{sub 2} mass eigenstate is trimaximally (democratically) mixed. This suggests a new parameterization of the remaining mixing degrees of freedom, which eschews mixing angles, dealing instead, directly with the complex parameter U{sub e3} of the mixing matrix. Unitarity triangles then take a particularly simple form, which we hope will facilitate comparison with experiment.
Date: January 18, 2006
Creator: Bjorken, James D.; /SLAC; Harrison, P.F.; U., /Warwick; Scott, W.G. & /Rutherford
Partner: UNT Libraries Government Documents Department

$\textit{CP}$ violation in $B_s^0 \rightarrow J/\psi \phi$ at the Tevatron

Description: The author reviews the history and present status of CP violation measurements made during RunII of the Fermilab Tevatron. Both flavor-tagged and untagged measurements of the Cp-violating phase {beta}{sub s}{sup J/{Psi}} are discussed, as well as measurements of the width difference {Delta}{Lambda}{sub s} between heavy and light B{sub s}{sup 0} mass eigenstates made in the B{sub s}{sup 0} {yields} J/{Psi}{phi} system.
Date: January 1, 2009
Creator: Gibson, Karen & U., /Pittsburgh
Partner: UNT Libraries Government Documents Department

Measurement of B0(s) mixing parameters from the flavor-tagged decay B0(s) ---> J/psi phi

Description: From an analysis of the flavor-tagged decay B{sub s}{sup 0} {yields} J/{psi}{phi} they obtain the width difference between the B{sub s}{sup 0} light and heavy mass eigenstates, {Delta}{Lambda}{sub s} {triple_bond} {Lambda}{sub L} - {Lambda}{sub H} = 0.19 {+-} 0.07(stat){sub -0.01}{sup +0.02}(syst) ps{sup -1}, and the CP-violating phase, {phi}{sub s} = -0.57{sub -0.30}{sup +0.24}(stat){sub -0.02}{sup +0.07}(syst). The allowed 90% C.L. intervals of {Delta}{Lambda}{sub s} and {phi}{sub s} are 0.06 < {Delta}{Lambda}{sub s} < 0.30 ps{sup -1} and -1.20 < {phi}{sub s} < 0.06, respectively. The data sample corresponds to an integrated luminosity of 2.8 fb{sup -1} accumulated with the D0 detector at the Fermilab Tevatron collider.
Date: February 1, 2008
Creator: Abazov, V.M.; /Dubna, JINR; Abbott, B.; U., /Oklahoma; Abolins, M.; U., /Michigan State et al.
Partner: UNT Libraries Government Documents Department

Measurements of the Branching Fractions and CP Asymmetries of B -> D0_CP K Decays

Description: We present a study of the decay B{sup -} {yields} D{sub (CP)}{sup 0} K{sup -} and its charge conjugate, where D{sub (CP)}{sup 0} is reconstructed in CP-even, CP-odd, and non-CP flavor eigenstates, based on a sample of 232 million {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEP-II e{sup +}e{sup -} storage ring. We measure the partial-rate charge asymmetries AC{sub CP{+-}} and the ratios R{sub CP{+-}} of the B {yields} D{sup 0} K decay branching fractions as measured in CP{+-} and non-CP D{sup 0} decays: A{sub CP+} = 0.35 {+-} 0.13(stat) {+-} 0.04(syst), A{sub CP-} = -0.06 {+-} 0.13(stat) {+-} 0.04(syst), R{sub CP+} = 0.90 {+-} 0.12(stat) {+-} 0.04(syst), R{sub CP-} = 0.86 {+-} 0.10(stat) {+-} 0.05(syst).
Date: January 5, 2006
Creator: Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
Partner: UNT Libraries Government Documents Department

Symplectic Symmetry and the Ab Initio No-Core Shell Model

Description: The symplectic symmetry of eigenstates for the 0{sub gs}{sup +} in {sup 16}O and the 0{sub gs}{sup +} and lowest 2{sup +} and 4{sup +} configurations of {sup 12}C that are well-converged within the framework of the no-core shell model with the JISP16 realistic interaction is examined. These states are found to project at the 85-90% level onto very few symplectic representations including the most deformed configuration, which confirms the importance of a symplectic no-core shell model and reaffirms the relevance of the Elliott SU(3) model upon which the symplectic scheme is built.
Date: March 14, 2007
Creator: Draayer, Jerry P.; Dytrych, Tomas; Sviratcheva, Kristina D.; Bahri, Chairul & Vary, James P.
Partner: UNT Libraries Government Documents Department

Measurement of CP violation observables and parameters for the decays $B^{\pm}\to DK^{*\pm}$

Description: We study the decay B{sup -} {yields} DK*{sup -} using a sample of 379 x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} events collected with the BABAR detector at the PEP-II B-factory. We perform a 'GLW' analysis where the D meson decays into either a CP-even (CP+) eigenstate (K{sup +}K{sup -}, {pi}{sup +}{pi}{sup -}), CP-odd (CP-) eigenstate (K{sub S}{sup 0}{pi}{sup 0}, K{sub S}{sup 0}{phi}, K{sub S}{sup 0}{omega}) or a non-CP state (K{sup -}{pi}{sup +}). We also analyze D meson decays into K{sup +}{pi}{sup -} from a Cabibbo-favored {bar D}{sup 0} decay or doubly suppressed D{sup 0} decay ('ADS' analysis). We measure observables that are sensitive to the CKM angle {gamma}: the partial-rate charge asymmetries A{sub CP{+-}}, the ratios R{sub CP{+-}} of the B-decay branching fractions in CP{+-} and non-CP decay, the ratio R{sub ADS} of the charge-averaged branching fractions, and the charge asymmetry A{sub ADS} of the ADS decays: A{sub CP+} = 0.09 {+-} 0.13 {+-} 0.06, A{sub CP-} = -0.23 {+-} 0.21 {+-} 0.07, R{sub CP+} = 2.17 {+-} 0.35 {+-} 0.09, R{sub CP-} = 1.03 {+-} 0.27 {+-} 0.13, R{sub ADS} = 0.066 {+-} 0.031 {+-} 0.010, and A{sub ADS} = -0.34 {+-} 0.43 {+-} 0.16, where the first uncertainty is statistical and the second is systematic. Combining all the measurements and using a frequentist approach yields the magnitude of the ratio between the Cabibbo-suppressed and favored amplitudes, r{sub B} = 0.31 with a one (two) sigma confidence level interval of [0.24, 0.38] ([0.17, 0.43]). The value r{sub B} = 0 is excluded at the 3.3 sigma level. A similar analysis excludes values of {gamma} in the intervals [0, 7]{sup o}, [55, 111]{sup o}, and [175, 180]{sup o} ([85, 99]{sup o}) at the one (two) sigma confidence level.
Date: August 26, 2010
Creator: Aubert, Bernard; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E.; Prudent, X. et al.
Partner: UNT Libraries Government Documents Department

Flavor Structure of Warped Extra Dimension Models

Description: We recently showed, in hep-ph/0406101, that warped extra dimensional models with bulk custodial symmetry and few TeV KK masses lead to striking signals at B-factories. In this paper, using a spurion analysis, we systematically study the flavor structure of models that belong to the above class. In particular we find that the profiles of the zero modes, which are similar in all these models, essentially control the underlying flavor structure. This implies that our results are robust and model independent in this class of models. We discuss in detail the origin of the signals in B-physics. We also briefly study other NP signatures that arise in rare K decays (K {yields} {pi}{nu}{nu}), in rare top decays [t {yields} c{gamma}(Z, gluon)] and the possibility of CP asymmetries in D{sup 0} decays to CP eigenstates such as K{sub s}{pi}{sup 0} and others. Finally we demonstrate that with light KK masses, {approx} 3 TeV, the above class of models with anarchic 5D Yukawas has a ''CP problem'' since contributions to the neutron electric dipole moment are roughly 20 times larger than the current experimental bound. Using AdS/CFT correspondence, these extra-dimensional models are dual to a purely 4D strongly coupled conformal Higgs sector thus enhancing their appeal.
Date: August 10, 2004
Creator: Agashe, Kaustubh; Perez, Gilad & Soni, Amarjit
Partner: UNT Libraries Government Documents Department

B physics: measurement of the lifetime difference between b_s mass eigenstates

Description: We present measurements of the lifetimes and polarization amplitudes for B{sub s}{sup 0} {yields} J/{psi}{phi} and B{sub d}{sup 0} {yields} J/{psi} K*{sup 0} decays. Lifetimes of the heavy (H) and light (L) mass eigenstates in the B{sub s}{sup 0} system are separately measured for the first time by determining the relative contributions of amplitudes with definite CP as a function of the decay time.
Date: April 28, 2005
Creator: Acosta, D. & Collaboration, The CDF
Partner: UNT Libraries Government Documents Department

Discretizing gravity in warped spacetime

Description: We investigate the discretized version of the compact Randall-Sundrum model. By studying the mass eigenstates of the lattice theory, we demonstrate that for warped space, unlike for flat space, the strong coupling scale does not depend on the IR scale and lattice size. However, strong coupling does prevent us from taking the continuum limit of the lattice theory. Nonetheless, the lattice theory works in the manifestly holographic regime and successfully reproduces the most significant features of the warped theory. It is even in some respects better than the KK theory, which must be carefully regulated to obtain the correct physical results. Because it is easier to construct lattice theories than to find exact solutions to GR, we expect lattice gravity to be a useful tool for exploring field theory in curved space.
Date: July 11, 2005
Creator: Schwartz, Matthew; Randall, Lisa; Schwartz, Matthew D. & Thambyahpillai, Shiyamala
Partner: UNT Libraries Government Documents Department

Measurement of Lifetime and Decay-Width Difference in B0s -> J/psi phi Decays

Description: The authors measure the mean lifetime, {tau} = 2/({Lambda}{sub L} + {Lambda}{sub H}), and the decay-width difference, {Delta}{Lambda} = {Lambda}{sub L} - {Lambda}{sub H}, of the light and heavy mass eigenstates of the B{sub s}{sup 0} meson, B{sub sL}{sup 0} and B{sub sH}{sup 0}, in B{sub s}{sup 0} {yields} J/{psi}{phi} decays using 1.7 fb{sup -1} of data collected with the CDF II detector at the Fermilab Tevatron p{bar p} collider. Assuming CP conservation, a good approximation for the B{sub s}{sup 0} system in the standard model, they obtain {Delta}{Lambda} = 0.076{sub -0.063}{sup +0.059}(stat.) {+-} 0.006(syst.) ps{sup -1} and {tau} = 1.52 {+-} 0.04(stat.) {+-} 0.02(syst.) ps, the most precise measurements to date. The constraints on the weak phase and {Delta}{Lambda} are consistent with CP conservation.
Date: December 1, 2007
Creator: Aaltonen, : T.
Partner: UNT Libraries Government Documents Department

Large-scale quantum mechanical simulations of high-Z metals

Description: High-Z metals constitute a particular challenge for large-scale ab initio calculations, as they require high resolution due to the presence of strongly localized states and require many eigenstates to be computed due to the large number of electrons and need to accurately resolve the Fermi surface. Here, we report recent findings on high-Z materials, using an efficient massively parallel planewave implementation on some of the largest computational architectures currently available. We discuss the particular architectures employed and methodological advances required to harness them effectively. We present a pair-correlation function for U, calculated using quantum molecular dynamics, and discuss relaxations of Pu atoms in the vicinity of defects in aged and alloyed Pu. We find that the self-irradiation associated with aging has a negligible effect on the compressibility of Pu relative to other factors such as alloying.
Date: January 3, 2007
Creator: Yang, L H; Hood, R; Pask, J & Klepeis, J
Partner: UNT Libraries Government Documents Department

Search for CP Violation in Neutral D Meson Cabibbo-suppressedThree-body Decays

Description: Using 385 fb{sup -1} of e{sup +}e{sup -} collision data collected at center-of-mass energies around 10.6 GeV, we search for time-integrated CP violation in the Cabibbo-suppressed decays D{sup 0}/{bar D}{sup 0} {yields} {pi}{sup -}{pi}{sup +}{pi}{sup 0} and D{sup 0}/{bar D}{sup 0} {yields} K{sup -}K{sup +}{pi}{sup 0} with both model-independent and model-dependent methods. Measurements of the asymmetries in amplitudes of flavor states and CP eigenstates provide constraints on theories beyond the Standard Model, some of which predict CP violation in amplitudes at the 1% level or higher. We find no evidence of CP violation and hence no conflict with the Standard Model.
Date: March 11, 2008
Creator: Aubert, B.
Partner: UNT Libraries Government Documents Department

Semileptonic B Decays, B Mixing And Magnitudes of CKM Elements at BaBar

Description: The value of |V{sub cb}| has been measured recently from a simultaneous fit to moments of the hadronic-mass and lepton-energy distributions in inclusive semileptonic B-mesons decays with a precision of 2%. Both exclusive and inclusive measurements of |V{sub ub}| have also been carried out in B {yields} X{sub u}{ell}{nu} decays. Precision measurements of the mixing parameter, {Delta}m{sub d}, have been obtained. In addition, direct limits on the total decay-rate difference {Delta}{Lambda} between the two B{sup 0} mass eigenstates and on CP, T and CPT violation due exclusively to oscillations have recently been provided by BaBar.
Date: October 11, 2005
Creator: Cote, D. & U., /Montreal
Partner: UNT Libraries Government Documents Department

Confined One Dimensional Harmonic Oscillator as a Two-Mode System

Description: The one-dimensional harmonic oscillator in a box problem is possibly the simplest example of a two-mode system. This system has two exactly solvable limits, the harmonic oscillator and a particle in a (one-dimensional) box. Each of the two limits has a characteristic spectral structure describing the two different excitation modes of the system. Near each of these limits, one can use perturbation theory to achieve an accurate description of the eigenstates. Away from the exact limits, however, one has to carry out a matrix diagonalization because the basis-state mixing that occurs is typically too large to be reproduced in any other way. An alternative to casting the problem in terms of one or the other basis set consists of using an ''oblique'' basis that uses both sets. Through a study of this alternative in this one-dimensional problem, we are able to illustrate practical solutions and infer the applicability of the concept for more complex systems, such as in the study of complex nuclei where oblique-basis calculations have been successful.
Date: July 11, 2005
Creator: Gueorguiev, V G; Rau, A P & Draayer, J P
Partner: UNT Libraries Government Documents Department

Study of Decays $B_d \to J/\psi+ K^*$ and $B_s \to J/\psi+ \phi$ with the D0 detector

Description: We present measurements of the linear polarization amplitudes and the strong relative phases that describe the flavor-untagged decays B{sub d} {yields} J/{Psi} K* and B{sub s} {yields} J/{Psi}{phi} in the transversity basis. We also measure the mean lifetime of the B{sub s} mass eigenstates and the lifetime ratio. The analyses are based on approximately 2.8 fb{sup -1} of data recorded with the D0 detector. From our measurements of the angular parameters we conclude that there is no evidence for a deviation from flavor SU(3) symmetry for these decays and that the factorization assumption is not valid for the B{sub d} {yields} J/{Psi} K* decay.
Date: January 1, 2009
Creator: Gutierrez, Phillip & U., /Oklahoma City
Partner: UNT Libraries Government Documents Department

B^0_s Oscillations

Description: For a long time the B{sub s}{sup 0}-{bar B}{sub s}{sup 0} system has eluded a complete investigation of its observables. Only recently the Tevatron experiments have accumulated sizable B{sub s}{sup 0} samples, which allow a direct and precise study of the system properties. This contribution reviews the most up-to-date measurements by the CDF and D0 Collaborations of the B{sub s}{sup 0}-{bar B}{sub s}{sup 0} system parameters: the mass and decay width differences, {Delta}m{sub s} and {Delta}{Lambda}{sub s}, between the heavy and light B{sub s}{sup 0} mass eigenstates, the average decay width {Lambda}{sub s}, and the CP-violating phase in the mixing {phi}{sub s}.
Date: December 1, 2007
Creator: Casarsa, Massimo
Partner: UNT Libraries Government Documents Department

Measurement of the B/s0 lifetime in B/s0 --> K+ K- decays

Description: A method is presented to simultaneously separate the contributions to a sample of B{sub (s)}{sup 0} {yields} h{sup +}h{sup {prime}-} decays, where h = {pi} or K, and measure the B meson lifetimes in the sample while correcting for the bias in the lifetime distributions due to the hadronic trigger at the CDF experiment. Using 1 fb{sup -1} of data collected at CDF the B{sup 0} lifetime is measured as {tau}{sub B{sup 0}} = 1.558{sub -0.047}{sup +0.050}{sub stat} {+-} 0.028{sub syst} ps, in agreement with the world average measurement. The B{sub s}{sup 0} lifetime in the B{sub s}{sup 0} {yields} K{sup +}K{sup -} decay is measured as {tau}{sub B{sub s}{sup 0} {yields} K{sup +}K{sup -}} = 1.51{sub -0.11}{sup +0.13}{sub stat} {+-} 0.04{sub syst} ps. No difference is observed between the lifetime and other measurements of the average B{sub s}{sup 0} lifetime or the lifetime of the light B{sub s}{sup 0} mass eigenstate determined from B{sub s}{sup 0} {yields} J/{psi}{phi} decays. With the assumptions that B{sub s}{sup 0} {yields} K{sup +}K{sup -} is 100% CP-even and that {tau}{sub B{sub s}{sup 0}} = {tau}{sub B{sup 0}} the width difference in the B{sub s}{sup 0} system is determined as {Delta}{Lambda}{sup CP}/{Lambda} = 0.03{sub -0.15}{sup +0.17}{sub stat} {+-} 0.05{sub syst} using the current world average B{sup 0} lifetime. This is consistent with zero and with the current world average measurement.
Date: February 1, 2009
Creator: Pounder, Nicola Louise
Partner: UNT Libraries Government Documents Department