Showing papers by "Hyun-Chul Kim published in 2005"

Measurement of the J/ψ meson and b-hadron production cross sections in pp̄ collisions at √s = 1960 GeV

Abstract: The authors present a new measurement of the inclusive and differential production cross sections of J/{psi} mesons and b-hadrons in proton-antiproton collisions at {radical}s = 1960 GeV The data correspond to an integrated luminosity of 397 pb{sup -1} collected by the CDF Run II detector They find the integrated cross section for inclusive J/{psi} production for all transverse momenta from 0 to 20 GeV/c in the rapidity range |y| 125 GeV/c They find the total cross section for b-hadrons, including both hadrons and anti-hadrons, decaying to J/{psi} with transverse momenta greater than 125 GeV/c in the rapidity range |y(J/{psi})| < 06, is 0330 {+-} 0005(stat){sub -0033}{sup +0036}(syst) {mu}b Using a Monte Carlo simulation of the decay kinematics of b-hadrons to all final states containing a J/{psi}, they extract the first measurement of the total single b-hadron cross section down to zero transverse momentum at {radical}s = 1960 GeV They find the total single b-hadron cross section integrated over all transverse momenta for b-hadrons in themore » rapidity range |y| < 06 to be 176 {+-} 04(stat){sub -23}{sup +25}(syst) {mu}b« less

Study of the B- → J/ΨK -π+π- decay and measurement of the B - → X(3872)K- branching fraction

Abstract: The authors study the decay B{sup -} {yields} J/{psi}K{sup -}{pi}{sup +}{pi}{sup -} using 117 million B{bar B} events collected at the {Upsilon}(4S) resonance with the BaBar detector at the PEP-II e{sup +}e{sup -} asymmetric-energy storage ring. They measure the branching fractions {Beta}(B{sup -} {yields} J/{psi}K{sup -} {pi}{sup +}{pi}{sup -}) = (116 {+-} 7(stat.) {+-} 9(syst.)) x 10{sup -5} and {Beta}(B{sup -} {yields} X(3872)K{sup -}) x {Beta}(X(3872) {yields} J/{psi}{pi}{sup +}{pi}{sup -}) = (1.28 {+-} 0.41) x 10{sup -5} and find the mass of the X(3872) to be 3873.4 {+-} 1.4MeV/c{sup 2}. They search for the h{sub c} narrow state in the decay B{sup -} {yields} h{sub c} K{sup -}, h{sub c} {yields} J/{psi}{pi}{sup +}{pi}{sup -} and for the decay B{sup -} {yields} J/{psi}D{sup 0}{pi}{sup -}, with D{sup 0} {yields} K{sup -}{pi}{sup +}. They set the 90% C.L. limits {Beta}(B{sup -} {yields} h{sub c}K{sup -}) x {Beta}(h{sub c} {yields} J/{psi}{pi}{sup +}{pi}{sup -}) < 3.4 x 10{sup -6} and {Beta}(B{sup -} {yields} J/{psi}D{sup 0}{pi}{sup -}) < 5.2 x 10{sup -5}.

Shape memory characteristics of Ti–22Nb–(2–8)Zr(at.%) biomedical alloys

Abstract: Shape memory characteristics of Ti–22Nb–(2–8)Zr(at.%) biomedical alloys were investigated by using tensile tests and X-ray diffraction (XRD) measurement. The alloy ingots were fabricated by an arc melting method. The ingots were cold-rolled by a reduction up to 95% in thickness at room temperature. All the alloys were solution-treated at 1173 K for 1.8 ks. The alloys subjected to the solution treatment exhibited large elongations ranging between 28 and 40%. The martensitic transformation temperature decreased by 38 K with 1 at.% increase of Zr content. The maximum recovered strain of 4.3% was obtained in the Ti–22Nb–4Zr(at.%) alloy. Ti–22Nb–(2–4)Zr(at.%) and Ti–22Nb–6Zr(at.%) alloys exhibited stable shape memory effect and superelastic behavior at room temperature, respectively.

Observation of a Near-Threshold ωJ/ψ Mass Enhancement in Exclusive B→KωJ/ψ Decays

Abstract: Reference EPFL-ARTICLE-154584doi:10.1103/PhysRevLett.94.182002View record in Web of Science Record created on 2010-11-05, modified on 2017-12-10

Dimension Reduction in Text Classification with Support Vector Machines

Abstract: Support vector machines (SVMs) have been recognized as one of the most successful classification methods for many applications including text classification. Even though the learning ability and computational complexity of training in support vector machines may be independent of the dimension of the feature space, reducing computational complexity is an essential issue to efficiently handle a large number of terms in practical applications of text classification. In this paper, we adopt novel dimension reduction methods to reduce the dimension of the document vectors dramatically. We also introduce decision functions for the centroid-based classification algorithm and support vector classifiers to handle the classification problem where a document may belong to multiple classes. Our substantial experimental results show that with several dimension reduction methods that are designed particularly for clustered data, higher efficiency for both training and testing can be achieved without sacrificing prediction accuracy of text classification even when the dimension of the input space is significantly reduced.

Shape Memory Behavior of Ti–22Nb–(0.5–2.0)O(at%) Biomedical Alloys

Abstract: In order to develop new biomedical shape memory alloys, mechanical properties and shape memory behavior of Ti-22Nb-(0.5-2.0)O(at%) alloys were investigated by tensile tests at various temperatures and X-ray diffraction measurement. The Ti-Nb-O alloys were fabricated by an arc melting method and then homogenized at 1273 K for 7.2ks. The ingots were cold-rolled with a reduction up to 98.5% in thickness and solution treated at 1173 K for 1.8 ks. The fracture stress of both as-rolled specimen and solution treated specimen increased with increasing oxygen content. A fracture stress of 1.37 GPa was obtained in the as-rolled Ti-22Nb-20 alloy. The martensitic transformation temperature decreased by 160 K per 1 at% increase of oxygen content. Superior shape memory effect and superelastic behavior were observed at room temperature in the Ti-22Nb-(0.5-1.5)O alloys. The addition of oxygen stabilized superelastic behavior of Ti-Nb alloys by increasing the critical stress for permanent deformation. The maximum shape recovery strain of 4.0% and the critical stress of 900 MPa for permanent deformation were obtained in the Ti-22Nb-0.5O and Ti-22Nb-1.50 alloys, respectively.

Measurement of double charmonium production in e+e- annihilations at s=10.6GeV

Abstract: We study $e^+e^-\to J/\psi c\bar{c}$ by measuring the invariant mass distribution recoiling against fully reconstructed $J/\psi$ decays, using 124 fb$^{-1}$ of data collected with a center-of-mass energy of 10.6 GeV with the $BaBar$ detector. We observe signals for $\eta_c(1S)$, $\chi_{c0}$, and $\eta_c(2S)$ in the recoil mass distribution, thus confirming previous measurements. We measure $\sigma(e^+e^-\to J/\psi+c\bar{c}) {\cal B} (c\bar{c} \to >2 charged)$ to be $17.6\pm2.8 (stat)^{+1.5}_{-2.1}(syst)$ fb, $ 10.3\pm2.5(stat)^{+1.4}_{-1.8}syst)$ fb, and $16.4\pm3.7(stat)^{+2.4}_{-3.0}(syst)$ fb with $c\bar{c}=\eta_c(1S)$, $\chi_{c0}$, and $\eta_c(2S)$, respectively.

e+e- → π+π -π+π-, K+K -π+π-, and K+K -K+K- cross sections at center-of-mass energies 0.5-4.5 GeV measured with initial-state radiation

Abstract: We study the process $e^+e^-\to\pi^+\pi^-\pi^+\pi^-\gamma$, with a hard photon radiated from the initial state. About 60,000 fully reconstructed events have been selected from 89 $fb^{-1}$ of BaBar data. The invariant mass of the hadronic final state defines the effective \epem center-of-mass energy, so that these data can be compared with the corresponding direct $e^+e^-$ measurements. From the $4\pi$-mass spectrum, the cross section for the process $e^+e^-\to\pi^+\pi^-\pi^+\pi^-$ is measured for center-of-mass energies from 0.6 to 4.5 $GeV/c^2$. The uncertainty in the cross section measurement is typically 5%. We also measure the cross sections for the final states $K^+ K^- \pi^+\pi^-$ and $K^+ K^- K^+ K^-$. We observe the $J/\psi$ in all three final states and measure the corresponding branching fractions. We search for X(3872) in $J/\psi (\to\mu^+\mu^-) \pi^+\pi^-$ and obtain an upper limit on the product of the $e^+e^-$ width of the X(3872) and the branching fraction for $X(3872) \to J/\psi\pi^+\pi^-$.

Search for lepton flavor violation in the decay τ±→μ ±γ

Abstract: A search for the nonconservation of lepton flavor number in the decay tau(+/-)->mu(+/-)gamma has been performed using 2.07 x 10(8) e(+)e(-)->tau(+)tau(-) events produced at a center-of-mass energy near 10.58 GeV with the BABAR detector at the PEP-II storage ring. We find no evidence for a signal and set an upper limit on the branching ratio of B(tau(+/-)->mu(+/-)gamma) < 6.8 x 10(-8) at 90% confidence level.

Dalitz-plot analysis of the decays B±→K±π∓π±

Abstract: We report a Dalitz-plot analysis of the charmless hadronic decays of charged B mesons to the final state K+/- pi-/+ pi+/-. Using a sample of 226.0 +/- 2.5 million BBbar pairs collected by the BaBar detector, we measure the magnitudes and phases of the intermediate resonant and nonresonant amplitudes for both charge conjugate decays. We present measurements of the corresponding branching fractions and their charge asymmetries that supersede those of previous BaBar analyses. We find the charge asymmetries to be consistent with zero.

Measurements of the B → Xsγ Branching Fraction and Photon Spectrum from a Sum of Exclusive Final States

Abstract: Using 88.9 million BB events collected by the BaBar detector at the Y(4S), we measure the branching fraction for the radiative penguin process B -> X_s gamma from the sum of 38 exclusive final states. The inclusive branching fraction above a minimum photon energy E_gamma > 1.9 GeV is BF (b -> s gamma) = (3.27 +/- 0.18 (stat.) +0.55/-0.40 (syst.) +0.04/-0.09 (theory)) 10^-4. We also measure the isospin asymmetry between B^- -> X_s ubar gamma and B^0bar -> X_s dbar gamma to be Delta_0- = -0.006 +/- 0.058 (stat.) +/- 0.009 (syst.) +/- 0.024 (B^0bar / B^-). The photon energy spectrum is measured in the B rest frame, from which moments are derived for different values of the minimum photon energy. We present fits to the photon spectrum and moments which give the heavy-quark parameters m_b and mu_pi^2. The fitted parameters are consistent with those obtained from semileptonic B -> X_c l nu decays, and are useful inputs for the extraction of Vub from measurements of semileptonic B -> X_u l nu decays.

Search for a charged partner of the X(3872) in the B meson decay B→X-K, X-→J/ψπ-π0

Abstract: We search for a charged partner of the X(3872) in the decay B --> X- K, X- --> J/psi pi- pi0, using 234 million BBbar events collected at the Y(4S) resonance with the BaBar detector at the PEP-II e+e- asymmetric-energy storage ring. The resulting product branching fraction upper limits are BR(B0 --> X- K+, X- --> J/psi pi- pi0) X- K0bar,X- --> J/psi pi- pi0) < 22 x 10(-6) at the 90% confidence level.

Measurement of the B+→pp̄K+ branching fraction and study of the decay dynamics

Abstract: With a sample of 232x10^6 Upsilon(4S) --> BBbar events collected with the BaBar detector, we study the decay B+ --> p pbar K+ excluding charmonium decays to ppbar We measure a branching fraction Br(B+ --> p pbar K+)=(67+/-05+/-04)x10^{-6} An enhancement at low ppbar mass is observed and the Dalitz plot asymmetry suggests dominance of the penguin amplitude in this B decay We search for a pentaquark candidate Theta*++ decaying into pK+ in the mass range 143 to 200 GeV/c2 and set limits on Br(B+ --> Theta*++pbar)xBr(Theta*++ --> pK+) at the 10^{-7} level

Time-integrated and time-dependent angular analyses of B → J/ψKπ: A measurement of cos2β with no sign ambiguity from strong phases

Abstract: We present results on B -> J/yKp decays using e+e-annihilation data collected with the BABAR detector at the U(4S) resonance. The detector is located at the PEP-II asym.-energy storage ring facility at the Stanford Linear Accelerator Center. Using approx. 88*106 B-B pairs, we measure the decay amplitudes for the flavor eigenmodes and observe strong-phase differences indicative of final-state interactions with a significance of 7.6 std. deviations. We use the interference between the Kp S-wave and P-wave amplitudes in the region of the K*(892) to resolve the ambiguity in the detn. of these strong phases. We then perform an ambiguity-free measurement of cos2b using the angular and time-dependent asymmetry in B -> J/yK*0(KS0p0) decays. With sin2b fixed at its measured value and cos2b treated as an independent parameter, we find cos2b=2.72-0.79+0.50(stat)+-0.27(syst), detg. the sign of cos2b to be pos. at 86% C.L. [on SciFinder (R)]

Improved measurement of CP asymmetries in B0→(c̄c) K0(*) decays

Abstract: We present results on time-dependent $CP$ asymmetries in neutral $B$ decays to several $CP$ eigenstates. The measurements use a data sample of about 227 million $\Upsilon$(4S) $\rightarrow B\overline{B}$ decays collected by the BABAR detector at the PEP-II asymmetric-energy $B$ Factory at SLAC. The amplitude of the CP asymmetry, sin2$\Beta$ in the Standard Model, is derived from decay-time distributions from events in which one neutral $B$ meson is fully reconstructed in a final state containing a charmonium meson and the other $B$ meson is determined to be either a $B^0$ or $\overline{B}^0$ from its decay products. We measure sin2$\Beta$ = 0.722 $\pm$ 0.040 (stat.) $\pm$ 0.23 (syst.) in agreement with the Standard Model expectation.

Study on reliability of metal fuse for sub-100nm technology

Abstract: Tungsten bit line fuse has been used for years in repair application but it fails during BOC (board on chip) package PCT (pressure cooker test) because of its weakness to corrosion. We searched for new material against corrosion, and metal-1 aluminum fuse was set up. Although there is no failure in PCT, we have found a fatal failure in IMD (inter-metal dielectric) crack during THB (temperature humidity bias test). We developed SiN full passivation scheme to resolve the failure then there is no failure until THB 1000 hours. Finally we set up metal-1 aluminum fuse process for sub-100 nm technology

Rapid sintering of ultra-fine WC-10 wt% Co by high-frequency induction heating

Abstract: High-frequency induction-heated sintering (HFIHS) is utilized to consolidate ultra-fine grain WC-10 wt% Co. Densification to near theoretical density in a relatively short time can be accomplished with insignificant change in grain size. WC-10 wt.% Co with a relative density of up to 99.5% was produced within 1 min with the simultaneous application of 60 MPa pressure. The average grain size of the densified material was about 260 nm and the mean free path in the cemented carbide was about 11 nm. The sintered material had fracture toughness and hardness values of 13 MPa.m1/2 and 1886 kg/mm2, respectively. The hardness is comparable to literature values but the fracture toughness is about two times higher. These results are interpreted in terms of current effects on sintering and mass transport. Higher heating rates result in higher density with smaller WC grain size, and higher current-induced solubility of WC in Co is proposed as an explanation for the high fracture toughness.

Simulation and fabrication of highly efficient InGaN‐based LEDs with corrugated interface substrate

Abstract: The external efficiency of normal LEDs is reduced by total internal reflection, which typically causes 50 to 80 percent of the emitted photons to be trapped in guided modes. We have increased the external quantum efficiency by using the corrugated interface substrate (CIS) texturing on the sapphire substrates to scatter light out of the nitride film. In order to maximize the outcoupling efficiency of the corrugation, we stimulated the outcoupling efficiency by varying the diameter, the period and the depth of the corrugations. With the use of the optimized corrugation pattern, the external quantum efficiency of 34% was achieved experimentally, without detriment to the forward and reverse electrical characteristics of LEDs. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Method of remapping flash memory

Abstract: A method of re-mapping a flash memory, which minimizes the number of times the flash memory, is accessed and helps to evenly use the entire area of the flash memory, is provided. The method includes arranging a plurality of physical units (101) yet to be mapped according to their erase count values (ECNT), and sequentially mapping the physical units (101) to a logic unit (100) in such a manner that a physical unit (101) having a smaller erase count value is mapped to the logic unit (100) ahead of a (101) having a larger erase count value.

Exotic and nonexotic magnetic transitions in the context of the SELEX and GRAAL experiments

Abstract: We calculate magnetic transition moments in the chiral quark-soliton model, with explicit SU(3)-symmetry breaking taken into account. The dynamical model parameters are fixed by experimental data for the magnetic moments of the baryon octet and from the recent measurements of ${\ensuremath{\Theta}}^{+}$ mass. Known magnetic transition moments ${\ensuremath{\mu}}_{\ensuremath{\Lambda}\ensuremath{\Sigma}}$, ${\ensuremath{\mu}}_{N\ensuremath{\Delta}}$ are reproduced and predictions for other octet-decuplet and octet-antidecuplet transitions are given. In particular ${\ensuremath{\mu}}_{\ensuremath{\Sigma}{\ensuremath{\Sigma}}^{*}}$ recently constrained by SELEX is shown to be below $0.82{\ensuremath{\mu}}_{N}$. The recent GRAAL data on $\ensuremath{\eta}$ photoproduction off the nucleon are explained in terms of a new narrow antidecuplet neutronlike resonance.

Extraction of semiconducting CNTs by repeated dielectrophoretic filtering

Abstract: We have separated semiconducting carbon nanotubes from as-grown batch material (HiPco production). A special configuration of electrodes which generates a 3-dimensional electric field gradient was used to filter out and deposit metallic carbon nanotubes by the dielectrophoretic method, leaving the remaining dispersion enriched in semiconducting nanotubes. The efficiency of filtering was determined by Raman spectroscopy. Using repeated deposition cycles, the ratio of semiconducting to metallic tubes was increased. After seven cycles, the proportion of semiconducting tubes in the remaining dispersion reached 94%.

Search for the decay B+ → K+ νν̄

Abstract: We search for the rare flavor-changing neutral-current decay ${B}^{+}\ensuremath{\rightarrow}{K}^{+}\ensuremath{ u}\overline{\ensuremath{ u}}$ in a data sample of $82\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ collected with the BABAR detector at the PEP-II $B$-factory. Signal events are selected by examining the properties of the system recoiling against either a reconstructed hadronic or semileptonic charged-$B$ decay. Using these two independent samples we obtain a combined limit of $\mathcal{B}({B}^{+}\ensuremath{\rightarrow}{K}^{+}\ensuremath{ u}\overline{\ensuremath{ u}})l5.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ at the 90% confidence level. In addition, by selecting for pions rather than kaons, we obtain a limit of $\mathcal{B}({B}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}\ensuremath{ u}\overline{\ensuremath{ u}})l1.0\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ using only the hadronic $B$ reconstruction method.

Measurement of B(t --> Wb)/B(t--> Wq) at the collider detector at fermilab.

Abstract: We present a measurement of the ratio of top-quark branching fractions R = B(t --> Wb)/B(t --> Wq), where q can be a b, s, or a d quark, using lepton-plus-jets and dilepton data sets with an integrated luminosity of approximately 162 pb(-1) collected with the Collider Detector at Fermilab during Run II of the Tevatron. The measurement is derived from the relative numbers of tt events with different multiplicity of identified secondary vertices. We set a lower limit of R > 0.61 at 95% confidence level.

Relationship between serum adiponectin concentration, pulse wave velocity and nonalcoholic fatty liver disease

Abstract: Objectives: We aimed to investigate the relationship between nonalcoholic fatty liver disease (NAFLD), serum adiponectin concentration and brachial-ankle pulse wave velocity (baPWV) as a risk marker for atherosclerosis. Methods: A total of 213 nonalcoholic subjects (67 males, 146 females) participated in this study. Division of subjects into the NAFLD group or the normal group was based on the existence of fatty liver detected by sonography. Results: Serum adiponectin levels in the NAFLD group were significantly lower than those in the normal group. After adjusting for age, body-mass index (BMI) and the homeostasis model of assessment (HOMA), there was a significant negative correlation between NAFLD and serum adiponectin level only in females (r ¼ 2 0.22, P ¼ 0.008). Multiple logistic regression analysis showed a tendency of inverse correlation between NAFLD and serum adiponectin level in females (P ¼ 0.055). After adjustment for age, BMI and HOMA value, serum adiponectin levels were inversely correlated with serum alanine aminotransferase (ALT) and gamma-glutamyltranspeptidase (GGT) levels (r ¼ 2 0.199 (P ¼ 0.004) and r ¼ 2 0.282 (P , 0.001)). On the other hand, baPWV in the NAFLD group was also significantly higher than that in the normal group in females (P ¼ 0.005). Individual levels of serum ALT, aspatate aminotransferase (AST), alkaline phosphatase (ALP) and GGT were positively correlated with baPWV after adjusting for age, sex, BMI, HOMA and systolic blood pressure (P , 0.05). Conclusion: Serum adiponectin level and baPWV were significantly associated with NAFLD and various liver enzymes, especially in females.

Amplitude analysis of the decay B±→π±π±π

Abstract: We present a Dalitz-plot analysis of charmless B+- decays to the final state pi+- pi+- pi-+ using 210 fb^-1 of data recorded by the BABAR experiment at sqrt(s) = 10.58 GeV. We measure the branching fractions B(B+- -> pi+- pi+- pi-+) = (16.2 +- 1.2 +- 0.9) x 10^-6 and B(B+- -> rho^0(770) pi+-) = (8.8 +- 1.0 +- 0.6 +0.1-0.7) x 10^-6. Measurements of branching fractions for the quasi-two-body decays B+- -> rho^0(1450) pi+-, B+- -> f_0(980) pi+- and B+- -> f_2(1270) pi+- are also presented. We observe no charge asymmetries for the above modes, and there is no evidence for the decays B+- -> chic0 pi+-, B+- -> f_0(1370) pi+- and B+- -> sigma pi+-.

Search for electroweak single-top-quark production in pp̄ collisions at √s = 1.96 TeV

Abstract: We report on a search for standard model t-channel and s-channel single-top quark production in pp collisions at a center of mass energy of 1.96 TeV. We use a data sample corresponding to 162 pb-1 recorded by the upgraded collider detector at Fermilab. We find no significant evidence for electroweak top quark production and set upper limits at the 95% confidence level on the production cross section, consistent with the standard model: 10.1 pb for the t-channel, 13.6 pb for the s-channel and 17.8 pb for the combined cross section of t- and s-channel. © 2005 The American Physical Society.