Showing papers by "Jie Zhang published in 2006"

Review of Particle Physics (2006)

Abstract: A booklet is available containing the Summary Tables and abbreviated versions of some of the other sections of this full Review. All tables, listings, and reviews (and errata) are also available on the Particle Data Group website: http://pdg.lbl.gov.

Search for neutral MSSM Higgs bosons at LEP

Abstract: The four LEP collaborations, ALEPH, DELPHI, L3 and OPAL, have searched for the neutral Higgs bosons which are predicted by the Minimal Supersymmetric standard model (MSSM). The data of the four collaborations are statistically combined and examined for their consistency with the background hypothesis and with a possible Higgs boson signal. The combined LEP data show no significant excess of events which would indicate the production of Higgs bosons. The search results are used to set upper bounds on the cross-sections of various Higgs-like event topologies. The results are interpreted within the MSSM in a number of “benchmark” models, including CP-conserving and CP-violating scenarios. These interpretations lead in all cases to large exclusions in the MSSM parameter space. Absolute limits are set on the parameter cosβ and, in some scenarios, on the masses of neutral Higgs bosons.

Measurements of branching fractions, rate asymmetries, and angular distributions in the rare decays B→Kℓ^+ℓ^- and B→K^*ℓ^+ℓ^-

Abstract: We present measurements of the flavor-changing neutral current decays B -> K center dot(+)center dot(-) and B -> K-*center dot(+)center dot(-), where center dot(+)center dot(-) is either an e(+)e(-) or mu(+)mu(-) pair. The data sample comprises 229x10(6) Upsilon(4S)-> B (B) over bar decays collected with the BABAR detector at the PEP-II e(+)e(-) storage ring. Flavor-changing neutral current decays are highly suppressed in the standard model and their predicted properties could be significantly modified by new physics at the electroweak scale. We measure the branching fractions B(B -> K center dot(+)center dot(-))=(0.34 +/- 0.07 +/- 0.02)x10(-6), B(B -> K-*center dot(+)center dot(-))=(0.78(-0.17)(+0.19)+/- 0.11)x10(-6), the direct CP asymmetries of these decays, and the relative abundances of decays to electrons and muons. For two regions in center dot(+)center dot(-) mass, above and below m(J/psi), we measure partial branching fractions and the forward-backward angular asymmetry of the lepton pair. In these same regions we also measure the K-* longitudinal polarization in B -> K-*center dot(+)center dot(-) decays. Upper limits are obtained for the lepton-flavor-violating decays B -> Ke mu and B -> K(*)e mu. All measurements are consistent with standard model expectations.

Study of e+e-→pp̄ using initial state radiation with BABAR

Abstract: The e{sup +}e{sup -}{yields}pp cross section is determined over a range of pp masses, from threshold to 4.5 GeV/c{sup 2}, by studying the e{sup +}e{sup -}{yields}pp{gamma} process. The data set corresponds to an integrated luminosity of 232 fb{sup -1}, collected with the BABAR detector at the PEP-II storage ring, at an e{sup +}e{sup -} center-of-mass energy of 10.6 GeV. The mass dependence of the ratio of electric and magnetic form factors, G{sub E}/G{sub M}, is measured for pp masses below 3 GeV/c{sup 2}; its value is found to be significantly larger than 1 for masses up to 2.2 GeV/c{sup 2}. We also measure J/{psi}{yields}pp and {psi}(2S){yields}pp branching fractions and set an upper limit on Y(4260){yields}pp production and decay.

Observation of a χc2′ candidate in γγ→DD̄ production at belle

Abstract: We report on a search for new resonant states in the process gamma gamma -> D (D) over bar. A candidate C-even charmonium state is observed in the vicinity of 3.93 GeV/c(2). The production rate and the angular distribution in the gamma gamma center-of-mass frame suggest that this state is the previously unobserved chi(')(c2), the 2(3)P(2) charmonium state.

Diverse CD81 Proteins Support Hepatitis C Virus Infection

Abstract: Hepatitis C virus (HCV) entry is dependent on CD81. To investigate whether the CD81 sequence is a determinant of HCV host range, we expressed a panel of diverse CD81 proteins and tested their ability to interact with HCV. CD81 large extracellular loop (LEL) sequences were expressed as recombinant proteins; the human and, to a low level, the African green monkey sequences bound soluble HCV E2 (sE2) and inhibited infection by retrovirus pseudotype particles bearing HCV glycoproteins (HCVpp). In contrast, mouse or rat CD81 proteins failed to bind sE2 or to inhibit HCVpp infection. However, CD81 proteins from all species, when expressed in HepG2 cells, conferred susceptibility to infection by HCVpp and cell culture-grown HCV to various levels, with the rat sequence being the least efficient. Recombinant human CD81 LEL inhibited HCVpp infectivity only if present during the virus-cell incubation, consistent with a role for CD81 after virus attachment. Amino acid changes that abrogate sE2 binding (I182F, N184Y, and F186S, alone or in combination) were introduced into human CD81. All three amino acid changes in human CD81 resulted in a molecule that still supported HCVpp infection, albeit with reduced efficiency. In summary, there is a remarkable plasticity in the range of CD81 sequences that can support HCV entry, suggesting that CD81 polymorphism may contribute to, but alone does not define, the HCV susceptibility of a species. In addition, the capacity to support viral entry is only partially reflected by assays measuring sE2 interaction with recombinant or full-length CD81 proteins.

Search for doubly charmed baryons Xi/cc+ and Xi/cc++ in BABAR

Abstract: We search for the production of doubly charmed baryons in e(+)e(-) annihilations at or near a center-of-mass energy of 10.58 GeV, in a data sample with an integrated luminosity of 232 fb(-1) recorded with the BABAR detector at the PEP-II storage ring at the Stanford Linear Accelerator Center. We search for Xi(+)(cc) baryons in the final states Lambda K-+(c)-pi(+) and Xi(0)(c)pi(+), and Xi(++)(cc) baryons in the final states Lambda K-+(c)-pi(+)pi(+) and Xi(0)(c)pi(+)pi(+). We find no evidence for the production of doubly charmed baryons.

The e+e-→3(π+π-), 2(π+π-π0) and K+K-2(π+π-) cross sections at center-of-mass energies from production threshold to 4.5 GeV measured with initial-state radiation

Abstract: We study the processes e^+e^- → 3(π^+π^-)γ, 2(π^+π^-π^0)γ and K^+K^-2(π^+π^-)γ, with the photon radiated from the initial state. About 20 000, 33 000 and 4000 fully reconstructed events, respectively, have been selected from 232 fb^(-1) of BABAR data. The invariant mass of the hadronic final state defines the effective e^+e^- center-of-mass energy, so that these data can be compared with the corresponding direct e^+e^- measurements. From the 3(π^+π^-), 2(π^+π^-π^0) and K^+K^-2(π^+π^-) mass spectra, the cross sections for the processes e^+e^- → 3(π^+π^-), e^+e^- → 2(π^+π^-π^0) and e^+e^- → K^+K^-2(π^+π^-) are measured for center-of-mass energies from production threshold to 4.5 GeV. The uncertainty in the cross section measurement is typically 6%–15%. We observe a structure at 1.9 GeV in both cross sections and a resonance structure with mass 1645 ± 0.008 GeV/c^2 and width 0.114 ± 0.014 GeV when the ω(782)η final state is extracted. We observe the J/ψ in all these final states and measure the corresponding branching fractions.

Structure at 2175 MeV in e+e-→ f0(980) observed via initial-state radiation

Abstract: We study the initial-state-radiation processes e+e-→K+K-π+π- γ and e+e-→K+K-π0π0γ using an integrated luminosity of 232fb-1 collected at the Υ(4S) mass with the BABAR detector at SLAC. Even though these reactions are dominated by intermediate states with excited kaons, we are able to study for the first time the cross section for e+e-→ (1020)f0(980) as a function of center-of-mass energy. We observe a structure near threshold consistent with a 1 - resonance with mass m=2.175±0. 010±0.015GeV/c2 and width Γ=58±16±20MeV. We observe no Y(4260) signal and set a limit of BY→ π+π-•ΓeeY<0. 4eV (90% confidence level), which excludes some models. © 2006 The American Physical Society.

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

Abstract: A search for the non-conservation of lepton flavor in the decay {tau}{sup {+-}} {yields} e{sup {+-}}{gamma} has been performed with 2.07 x 10{sup 8} e{sup +}e{sup -} {yields} {tau}{sup +}{tau}{sup -} events collected by the BABAR detector at the PEP-II storage ring at a center-of-mass energy near 10.58 GeV. They find no evidence for a signal and set an upper limit on the branching ratio of {Beta}({tau}{sup {+-}} {yields} e{sup {+-}}{gamma}) < 1.1 x 10{sup -7} at 90% confidence level.

Carbon and Nitrogen-codoped TiO2 with High Visible Light Photocatalytic Activity

Abstract: Titanium dioxide codoped with carbon and nitrogen was synthesized by a microemulsion-hydrothermal process. There was a synergistic effect for the carbon and nitrogen-codoped TiO 2 , which offset the deficiencies of carbon or nitrogen single doped TiO 2 . The results showed that the photocatalytic activity of C and N-codoped TiO 2 was considerably improved because the band gap of TiO 2 was greatly narrowed by C and N-codoping.

Expression of DC-SIGN and DC-SIGNR on human sinusoidal endothelium: a role for capturing hepatitis C virus particles.

Abstract: Hepatic sinusoidal endothelial cells are unique among endothelial cells in their ability to internalize and process a diverse range of antigens. DC-SIGNR, a type 2 C-type lectin expressed on liver sinusoids, has been shown to bind with high affinity to hepatitis C virus (HCV) E2 glycoprotein. DC-SIGN is a closely related homologue reported to be expressed only on dendritic cells and a subset of macrophages and has similar binding affinity to HCV E2 glycoprotein. These receptors function as adhesion and antigen presentation molecules. We report distinct patterns of DC-SIGNR and DC-SIGN expression in human liver tissue and show for the first time that both C-type lectins are expressed on sinusoidal endothelial cells. We confirmed that these receptors are functional by demonstrating their ability to bind HCV E2 glycoproteins. Although these lectins on primary sinusoidal cells support HCV E2 binding, they are unable to support HCV entry. These data support a model where DC-SIGN and DC-SIGNR on sinusoidal endothelium provide a mechanism for high affinity binding of circulating HCV within the liver sinusoids allowing subsequent transfer of the virus to underlying hepatocytes, in a manner analogous to DC-SIGN presentation of human immunodeficiency virus on dendritic cells.

Measurement of forward-backward asymmetry and Wilson coefficients in B --> K*l+l-.

Abstract: We report the first measurement of the forward-backward asymmetry and the ratios of Wilson coefficients A{sub 9}/A{sub 7} and A{sub 10}/A{sub 7} in B{yields}K{sup *}l{sup +}l{sup -}, where l represents an electron or a muon. We find evidence for the forward-backward asymmetry with a significance of 3.4{sigma}. The results are obtained from a data sample containing 386x10{sup 6} BB pairs that were collected on the {upsilon}(4S) resonance with the Belle detector at the KEKB asymmetric-energy e{sup +}e{sup -} collider.

Inhibition of poly(ADP-ribose) polymerase prevents irinotecan-induced intestinal damage and enhances irinotecan/temozolomide efficacy against colon carcinoma

Abstract: Poly(ADP-ribose) polymerase (PARP) inhibitors enhance the antitumor activity of the topoisomerase I inhibitor irinotecan (CPT-11), which is used to treat advanced colorectal carcinoma. Since PARP inhibitors sensitize tumor cells also to the methylating agent temozolomide (TMZ) and clinical trials are evaluating CPT-11 in combination with TMZ, we tested whether the PARP inhibitor GPI 15427 (10-(4-methyl-piperazin-1-ylmethyl)-2H-7-oxa-1,2-diaza-benzo[de]anthracen-3-one) increases the efficacy of CPT-11 + TMZ against colon cancer. Moreover, due to the ability of PARP inhibitors to avoid cell death consequent to PARP-1 overactivation, we evaluated whether oral administration of GPI 15427 provides protection from the dose-limiting intestinal toxicity of CPT-11. The results of colony formation assay indicated that GPI 15427 increased the antiproliferative effects (combination index <1) of TMZ + SN-38 (the active metabolite of CPT-11) against colon cancer cells. Accordingly, GPI 15427 (40 mg/kg/dayx5 days per os) in combination with TMZ (10 mg/kg/dayx5 days) + CPT-11 (4 mg/kg/dayx5 days) significantly reduced the growth of tumor xenografts. Oral administration of GPI 15427 (40 mg/kg/q2x3 days) prevented intestinal injury and diarrhea induced by CPT-11 (30 mg/kg/day x 3 days) reducing inflammation and PARP-1 overactivation, as evidenced by immunohistochemical staining of intestinal tissue with antipoly(ADP-ribose) antibody (Ab). In conclusion, the PARP inhibitor represents a novel strategy to enhance the antitumor efficacy and reduce toxicity of chemotherapy in colon cancer.

Study of the X(3872) and Y(4260) in B0→J/ψπ+π-K0 and B-→J/ψπ+π-K- decays

Abstract: We present results of a search for the X(3872) in B{sup 0}{yields}X(3872)K{sub S}{sup 0},X(3872){yields}J/{psi}{pi}{sup +}{pi}{sup -}, improved measurements of B{sup -}{yields}X(3872)K{sup -}, and a study of the J/{psi}{pi}{sup +}{pi}{sup -} mass region above the X(3872). We use 232x10{sup 6} BB pairs collected at the {upsilon}(4S) resonance with the BABAR detector at the PEP-II e{sup +}e{sup -} asymmetric-energy storage rings. The results include the 90% confidence interval 1.34x10{sup -6}

Observation of an excited charm baryon Ωc* decaying to Ωc0γ

Abstract: We report the first observation of an excited singly-charm baryon OmegaC* (css) in the radiative decay OmegaC0 Gamma, where the OmegaC0 baryon is reconstructed in the decays to the final states Omega-pi+, Omega-pi+pi0, Omega-pi+pi-pi+, and Cascade-K-pi+pi+. This analysis is performed using a dataset of 230.7 fb$-1} collected by the BABAR detector at the PEP-II asymmetric-energy B Factory at the Stanford Linear Accelerator Center. The mass difference between the OmegaC* and the OmegaC0 baryons is measured to be 70.8 +/- 1.0 (stat) +/- 1.1 (syst) MeV/c2. We also measure the ratio of inclusive production cross sections of OmegaC* and OmegaC0 in e+e- annihilation.

Measurements of the absolute branching fractions of B±→ K±Xcc̄

Abstract: We study the two-body decays of ${B}^{\ifmmode\pm\else\textpm\fi{}}$ mesons to ${K}^{\ifmmode\pm\else\textpm\fi{}}$ and a charmonium state ${X}_{c\overline{c}}$ in a sample of $210.5\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of data from the BABAR experiment. We perform measurements of absolute branching fractions $\mathcal{B}({B}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}{K}^{\ifmmode\pm\else\textpm\fi{}}{X}_{c\overline{c}})$ using a missing mass technique, and report several new or improved results. In particular, the upper limit $\mathcal{B}\mathbf{(}{B}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}{K}^{\ifmmode\pm\else\textpm\fi{}}X(3872)\mathbf{)}l3.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ at 90% C.L. and the inferred lower limit $\mathcal{B}\mathbf{(}X(3872)\ensuremath{\rightarrow}J/\ensuremath{\psi}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}\mathbf{)}g4.2%$ will help in understanding the nature of the recently discovered $X(3872)$.

Experimental constraints on the possible J**P quantum numbers of the Lambda(c)(2880)+

Abstract: We report the results of several studies of the {lambda}{sub c}{sup +}{pi}{sup +}{pi}{sup -}X final state in continuum e{sup +}e{sup -} annihilation data collected by the Belle detector. An analysis of angular distributions in {lambda}{sub c}(2880){sup +}{yields}{sigma}{sub c}(2455){sup 0,++}{pi}{sup +,-} decays strongly favors a {lambda}{sub c}(2880){sup +} spin assignment of (5/2) over (3/2) or (1/2). We find evidence for {lambda}{sub c}(2880){sup +}{yields}{sigma}{sub c}(2520){sup 0,++}{pi}{sup +,-} decay and measure the ratio of {lambda}{sub c}(2880){sup +} partial widths {gamma}({sigma}{sub c}(2520){pi})/{gamma}({sigma}{sub c}(2455){pi})=0.225{+-}0.062{+-}0.= 025. This value favors the {lambda}{sub c}(2880){sup +} spin-parity assignment of (5/2){sup +} over (5/2){sup -}. We also report the first observation of {lambda}{sub c}(2940){sup +}{yields}{sigma}{sub c}(2455){sup 0,++}{pi}{sup +,-} decay and measure {lambda}{sub c}(2880){sup +} and {lambda}{sub c}(2940){sup +} mass and width parameters. These studies are based on a 553 fb{sup -1} data sample collected at or near the {upsilon}(4S) resonance at the KEKB collider.

Measurement of the η and η′ transition form factors at q2=112GeV2

Abstract: We report a study of the processes e^+e^-→ηγ and e^+e^-→η′γ at a center-of-mass energy of 10.58 GeV, using a 232 fb^(-1) data sample collected with the BABAR detector at the PEP-II collider at SLAC. We observe 20_(-5)^(+6)ηγ and 50_(-7)^(+8)η′γ events over small backgrounds, and measure the cross sections σ(e^+e^-→ηγ)=4.5_(-1.1)^(+1.2)±0.3 fb and σ(e^+e^-→η′γ)=5.4±0.8±0.3 fb. The corresponding transition form factors at q^2=112 GeV^2 are q^2|F_η(q^2)|=0.229±0.030±0.008 GeV, and q^2|F_η′(q^2)|=0.251±0.019±0.008 GeV, respectively.

Characterization of the local structures of Ti-MCM-41 and their photocatalytic reactivity for the decomposition of NO into N2 and O2.

Abstract: Ti-MCM-41 mesoporous molecular sieves were prepared at ambient temperature and were characterized by X-ray absorption near-edge structure and extended X-ray absorption fine structure, UV-vis, Fourier transform infrared spectroscopy, and photoluminescence spectroscopic analyses. It was found that an increase in the Ti content caused the structure of the Ti-oxides in Ti-MCM-41 to change from an isolated tetrahedral coordination to adjacent Ti-oxide species with Ti4+ of tetrahedral coordination. The photocatalytic reactivity of these catalysts for the decomposition of NO into N2 and O2 was found to strongly depend on the local structure of the Ti-oxide species including their coordination and distribution, i.e., the charge transfer excited state of the highly dispersed isolated tetrahedrally coordinated Ti-oxides act as the active sites for the photocatalytic decomposition of NO into N2 and O2.

Measurement of the branching fraction and photon energy moments of B→Xsγ and ACP(B→Xs+dγ)

Abstract: The photon spectrum in B -> X-s gamma decay, where X-s is any strange hadronic state, is studied using a data sample of 88.5x10(6) e(+)e(-)->Upsilon(4S)-> B(B) over bar decays collected by the BABAR experiment at the Stanford Linear Accelerator Center. The partial branching fraction, Delta B(B -> X-s gamma)=(3.67 +/- 0.29(stat)+/- 0.34(syst)+/- 0.29(model))x10(-4), the first moment =2.288 +/- 0.025 +/- 0.017 +/- 0.015 GeV, and the second moment =0.0328 +/- 0.0040 +/- 0.0023 +/- 0.0036 GeV2 are measured for the photon energy range 1.9 GeV 1.6 GeV. In addition, the direct CP asymmetry A(CP)(B -> Xs+d gamma) is measured to be -0.110 +/- 0.115(stat)+/- 0.017(syst).

Dalitz Plot Analysis of the Decay B+ -> K+K+K-

Abstract: The authors perform an analysis of the three-body charmless decay B{sup {+-}} {yields} K{sup {+-}}K{sup {+-}}K{sup {-+}} using a sample of 226.0 {+-} 2.5 million B{bar B} pairs collected by the BABAR detector and measure the total branching fraction and Cp asymmetry to be {beta} = (35.2 {+-} 0.9 {+-} 1.6) x 10{sup -6} and A{sub CP} = (-1.7 {+-} 2.6 {+-} 1.5)%. They fit the Dalitz plot distribution using an isobar model and report the measured values of magnitudes and phases of the production coefficients. The decay dynamics is dominated by the K{sup +}K{sup -} S-wave, for which we perform a partial-wave analysis in the region m(K{sup +}K{sup -}) < 2 GeV/c{sup 2}. They find no evidence of CP violation for individual components of the isobar model.

Observation of B+→K̄0K+ and B0→K0K̄0

Abstract: The authors report observations of the b {yields} d penguin-dominated decays B{sup +} {yields} {bar K}{sup 0}K{sup +} and B{sup 0} {yields} K{sup 0}{bar K}{sup 0} in approximately 350 million {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector. They measure the branching fractions {Beta}(B{sup +} {yields} {bar K}{sup 0}K{sup +}) = (1.61 {+-} 0.44 {+-} 0.09) x 10{sup -6} and {Beta}(B{sup 0} {yields} K{sup 0}{bar K}{sup 0}) = (1.08 {+-} 0.28 {+-} 0.11) x 10{sup -6}, and the CP-violating charge asymmetry {Alpha}{sub CP} ({bar K}{sup 0} K{sup +}) = 0.10 {+-} 0.26 {+-} 0.03. Using a vertexing technique previously employed in several analyses of all-neutral final states containing kaons, they report the first measurement of time-dependent CP-violating asymmetries in B{sup 0} {yields} K{sub S}{sup 0}K{sub S}{sup 0}, obtaining S = -1.28{sub -0.73 -0.16}{sup +0.80 +0.11} and C = -0.40 {+-} 0.41 {+-} 0.06. They also report improved measurements of the branching fraction {Beta}(B{sup +} {yields} K{sup 0} {pi}{sup +}) = (23.9 {+-} 1.1 {+-} 1.0) x 10{sup -6} and CP-violating charge asymmetry {Alpha}{sub CP} (K{sup 0} {pi}{sup +}) = -0.029 {+-} 0.039 {+-} 0.010.

Measurement of the inclusive electron spectrum in charmless semileptonic B decays near the kinematic end point and determination of |Vub|

Abstract: We present a measurement of the inclusive electron spectrum in B → X_ueν decays near the kinematic limit for B → X_ceν transitions, using a sample of 88 × 10^6 BB pairs recorded by the BABAR detector at the Υ (4S resonance. Partial branching fraction measurements are performed in five overlapping intervals of the electron momentum; for the interval of 2.0 – 2.6 GeV/c we obtain ΔB (B → X_ueν) = (0.572 ± 0.041_(stat) ± 0.065_(syst)) × 10^(−3). Combining this result with shape function parameters extracted from BABAR measurements of moments of the inclusive photon spectrum in B → X_sγ decays and moments of the hadron-mass and lepton-energy spectra in B → X_clν decays we determine │Vub|= (4.44 ± 0.25 + 0.4_( exp−0.38SF) ± 0.22_(theory)) × 10^(−3). Here the first error represents the combined statistical and systematic experimental uncertainties of the partial branching fraction measurement, the second error refers to the uncertainty of the determination of the shape function parameters, and the third error is due to theoretical uncertainties in the QCD calculations.

Search for T, CP, and CPT violation in B0-B0 mixing with inclusive dilepton events.

Abstract: The authors report the results of a search for T, CP and CPT violation in B{sup 0}-{bar B}{sup 0} mixing using an inclusive dilepton sample collected by the BABAR experiment at the PEP-II B Factory. Using a sample of 232 million B{bar B} pairs, with a simultaneous likelihood fit of the same-sign and opposite-sign dileptons, they measure the T and Cp violation parameter |q/p|-1 = (-0.8 {+-} 2.7(stat.) {+-} 1.9(syst.)) x 10{sup -3}, and the CPT and CP parameters Im z = (-13.9 {+-} 7.3(stat.) {+-} 3.2(syst.)) x 10{sup -3} and {Delta}{Lambda} x Re z = (-7.1 {+-} 3.9(stat.) {+-} 2.0(syst.)) x 10{sup -3} ps{sup -1}. The statistical correlation between the measurements of Im z and {Delta}{Lambda} x Re z is 76%.

Charge asymmetry of same-sign dileptons in B0-B̅0 mixing

Abstract: Reference EPFL-ARTICLE-154552doi:10.1103/PhysRevD.73.112002View record in Web of Science Record created on 2010-11-05, modified on 2017-12-10