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141.
We applied ab initio order‐N elongation (ELG) method to calculate electronic structures of various deoxyribonucleic acid (DNA) models. We aim to test potential application of the method for building a database of DNA electronic structures. The ELG method mimics polymerization reactions on a computer and meets the requirements for linear scaling computational efficiency and high accuracy, even for huge systems. As a benchmark test, we applied the method for calculations of various types of random sequenced A‐ and B‐type DNA models with and without counterions. In each case, the ELG method maintained high accuracy with small errors in energy on the order of 10?8 hartree/atom compared with conventional calculations. We demonstrate that the ELG method can provide valuable information such as stabilization energies and local densities of states for each DNA sequence. In addition, we discuss the “restarting” feature of the ELG method for constructing a database that exhaustively covers DNA species. © 2015 Wiley Periodicals, Inc. 相似文献
142.
Through‐space/bond orbital interaction analysis has been applied to investigate the stereoelectronic effects on stabilizing the transition state of Menshutkin‐type SN2 reactions. The mechanism of how the substituent effects work on accelerating the reactions has been demonstrated from orbital interaction perspective. The geometrical structures and Mulliken charge distributions have been compared to elucidate the substituent effects for the SN2 reaction center. It is found that the substituents lower the activation energies by strengthening the orbital interactions in the SN2 reaction process. When electron‐donating and electron‐accepting substituents (–C6H5 and –CHO) are introduced to the same central carbon at the reaction center, the symmetry allows the π–π* interactions among the donor and acceptor in the transition state. It stabilizes the transition state much more than the reactant complex. And the π–π* interactions are estimated to decrease about 2.28 kcal/mol of the energy for transition state. The σ‐like orbitals of the partial bond around the central carbon are reactive, and the σ–π* orbital interactions stabilize the reactant complex much more than the π–σ* interaction. When the σ–π* and π–σ* interactions are deleted from the system, the activation energy increases and turns close to the values of the systems which are without such substituents. It can be concluded that the π–π*, σ–π*, and π–σ* interactions cooperatively accelerates the SN2 reaction by stabilizing its transition state. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
143.
Aubert B Bona M Boutigny D Karyotakis Y Lees JP Poireau V Prudent X Tisserand V Zghiche A Garra Tico J Grauges E Lopez L Palano A Pappagallo M Eigen G Stugu B Sun L Abrams GS Battaglia M Brown DN Button-Shafer J Cahn RN Groysman Y Jacobsen RG Kadyk JA Kerth LT Kolomensky YG Kukartsev G Lopes Pegna D Lynch G Mir LM Orimoto TJ Osipenkov IL Ronan MT Tackmann K Tanabe T Wenzel WA del Amo Sanchez P Hawkes CM Watson AT Held T Koch H Pelizaeus M Schroeder T Steinke M Walker D Asgeirsson DJ 《Physical review letters》2007,99(20):201801
We present a search for the lepton flavor violating decay B+-->K+ tau-/+ mu+/- using 383 x 10;{6} BB[over ] events collected by the BABAR experiment. The branching fraction for this decay can be substantially enhanced in new physics models. The kinematics of the tau from the signal B decay are inferred from the K+, mu, and other B in the event, which is fully reconstructed in one of a variety of hadronic decay modes, allowing the signal B candidate to be fully reconstructed. We observe no excess of events over the expected background and set a limit of B(B+-->K+ tau mu)<7.7 x 10(-5) at 90% confidence level, where the branching fraction is for the sum of the K+ tau- mu+ and K+ tau+mu- final states. We use this result to improve a model-independent bound on the energy scale of flavor-changing new physics. 相似文献
144.
Aubert B Bona M Boutigny D Karyotakis Y Lees JP Poireau V Prudent X Tisserand V Zghiche A Garra Tico J Grauges E Lopez L Palano A Pappagallo M Eigen G Stugu B Sun L Abrams GS Battaglia M Brown DN Button-Shafer J Cahn RN Groysman Y Jacobsen RG Kadyk JA Kerth LT Kolomensky YG Kukartsev G Lopes Pegna D Lynch G Mir LM Orimoto TJ Osipenkov IL Ronan MT Tackmann K Tanabe T Wenzel WA Del Amo Sanchez P Hawkes CM Watson AT Held T Koch H Pelizaeus M Schroeder T Steinke M Walker D Asgeirsson DJ 《Physical review letters》2007,99(22):221801
We report the observation of charmless hadronic decays of charged B mesons to the final state K{+}K{-}pi{+}. Using a data sample of 347.5 fb{-1} collected at the Upsilon(4S) resonance with the BABAR detector, we observe 429+/-43 signal events with a significance of 9.6sigma. We measure the inclusive branching fraction B(B{+}-->K{+}K{-}pi{+})=[5.0+/-0.5(stat)+/-0.5(syst)]x10{-6}. Inspection of the Dalitz plot of signal candidates shows a broad structure peaking near 1.5 GeV/c{2} in the K+K- invariant mass distribution. We find the direct CP asymmetry to be consistent with zero. 相似文献
145.
Aubert B Bona M Boutigny D Karyotakis Y Lees JP Poireau V Prudent X Tisserand V Zghiche A Tico JG Grauges E Lopez L Palano A Eigen G Stugu B Sun L Abrams GS Battaglia M Brown DN Button-Shafer J Cahn RN Groysman Y Jacobsen RG Kadyk JA Kerth LT Kolomensky YG Kukartsev G Pegna DL Lynch G Mir LM Orimoto TJ Ronan MT Tackmann K Wenzel WA Del Amo Sanchez P Hawkes CM Watson AT Held T Koch H Lewandowski B Pelizaeus M Schroeder T Steinke M Walker D Asgeirsson DJ Cuhadar-Donszelmann T Fulsom BG Hearty C 《Physical review letters》2007,99(16):161802
We analyze the decay B0-->K+K-K0 using 383 x 10(6) BB events collected by the BABAR detector at SLAC to extract CP violation parameter values over the Dalitz plot. Combining all K+K-K0 events, we find ACP=-0.015+/-0.077+/-0.053 and beta eff = 0.352+/-0.076+/-0.026 rad, corresponding to a CP violation significance of 4.8 sigma. A second solution near pi/2-beta eff is disfavored with a significance of 4.5 sigma. We also report ACP and beta eff separately for decays to phi(1020)K0, f0(980)K0, and K+K-K0 with mK+K- > 1.1 GeV/c2. 相似文献
146.
Aubert B Bona M Boutigny D Karyotakis Y Lees JP Poireau V Prudent X Tisserand V Zghiche A Grauges E Palano A Chen JC Qi ND Rong G Wang P Zhu YS Eigen G Ofte I Stugu B Abrams GS Battaglia M Brown DN Button-Shafer J Cahn RN Groysman Y Jacobsen RG Kadyk JA Kerth LT Kolomensky YG Kukartsev G Lopes Pegna D Lynch G Mir LM Orimoto TJ Pripstein M Roe NA Ronan MT Tackmann K Wenzel WA Del Amo Sanchez P Barrett M Harrison TJ Hart AJ Hawkes CM Watson AT Held T Koch H Lewandowski B Pelizaeus M Peters K 《Physical review letters》2007,98(9):091801
We report the results of a study of the exclusive charmless semileptonic decay, B0-->pi(-l)(+nu), undertaken with approximately 227 x 10(6) BB pairs collected at the Upsilon(4S) resonance with the BABAR detector. The analysis uses events in which the signal B decays are reconstructed with an innovative loose neutrino reconstruction technique. We obtain partial branching fractions in 12 bins of q2, the momentum transfer squared, from which we extract the f + (q2) form-factor shape and the total branching fraction B(B0-->pi(-l)(+nu))=(1.46+/-0.07stat+/-0.08syst) x 10(-4). Based on a recent unquenched lattice QCD calculation of the form factor in the range q2>16 GeV2, we find the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element /Vub/ to be (4.1+/-0.2stat +/- 0.2syst(+0.6)-0.4_{FF}) x 10(-3), where the last uncertainty is due to the normalization of the form factor. 相似文献
147.
Aubert B Barate R Bona M Boutigny D Couderc F Karyotakis Y Lees JP Poireau V Tisserand V Zghiche A Grauges E Palano A Pappagallo M Chen JC Qi ND Rong G Wang P Zhu YS Eigen G Ofte I Stugu B Abrams GS Battaglia M Brown DN Button-Schafer J Cahn RN Charles E Day CT Gill MS Groysman Y Jacobsen RG Kadyk JA Kerth LT Kolomensky YG Kukartsev G Lynch G Mir LM Oddone PJ Orimoto TJ Pripstein M Roe NA Ronan MT Wenzel WA Barrett M Ford KE Harrison TJ Hart AJ Hawkes CM Morgan SE Watson AT Goetzen K Held T 《Physical review letters》2007,98(1):012001
A search for charmed baryons decaying to D(0)p reveals two states: the Lambdac(2880)+ baryon and a previously unobserved state at a mass of [2939.8+/-1.3(stat)+/-1.0(syst)] MeV/c2 and with an intrinsic width of [17.5+/-5.2(stat)+/-5.9(syst)] MeV. Consistent and significant signals are observed for the K(-)pi(+) and K(-)pi(+)pi(-)pi(+) decay modes of the D0 in 287 fb(-1) annihilation data recorded by the BABAR detector at a center-of-mass energy of 10.58 GeV. There is no evidence in the D+p spectrum of doubly charged partners. The mass and intrinsic width of the Lambdac(2880)+ baryon and relative yield of the two baryons are also measured. 相似文献
148.
Aubert B Bona M Boutigny D Karyotakis Y Lees JP Poireau V Prudent X Tisserand V Zghiche A Grauges E Lopez L Palano A Chen JC Qi ND Rong G Wang P Zhu YS Eigen G Ofte I Stugu B Abrams GS Battaglia M Brown DN Button-Shafer J Cahn RN Groysman Y Jacobsen RG Kadyk JA Kerth LT Kolomensky YG Kukartsev G Pegna DL Lynch G Mir LM Orimoto TJ Pripstein M Roe NA Ronan MT Tackmann K Wenzel WA Del Amo Sanchez P Barrett M Harrison TJ Hart AJ Hawkes CM Watson AT Held T Koch H Lewandowski B Pelizaeus M 《Physical review letters》2007,99(25):251801
We report the results of a CP violation analysis of the decay B{+/-}-->D{pi{+}pi{-}pi;{0}}K{+/-}, where D{pi{+}pi{-}pi{0}} indicates a neutral D meson detected in the final state pi{+}pi{-}pi{0}, excluding K{S}{0}pi{0}. The analysis makes use of 324 x 10{6}e{+}e{-}-->BB[over ] events recorded by the BABAR experiment at the PEP-II e;{+}e;{-} storage ring. Analyzing the pi;{+}pi;{-}pi;{0} Dalitz plot distribution and the B{+/-}-->D{pi{+}pi{-}pi{0}}K{+/-} branching fraction and decay rate asymmetry, we find the following one-standard-deviation constraints on the amplitude ratio and on the weak and strong phases: 0.06pi{+}pi{-}pi{0} decay amplitude. 相似文献
149.
Aubert B Barate R Bona M Boutigny D Couderc F Karyotakis Y Lees JP Poireau V Tisserand V Zghiche A Grauges E Palano A Pappagallo M Chen JC Qi ND Rong G Wang P Zhu YS Eigen G Ofte I Stugu B Abrams GS Battaglia M Brown DN Button-Shafer J Cahn RN Charles E Day CT Gill MS Groysman Y Jacobsen RG Kadyk JA Kerth LT Kolomensky YG Kukartsev G Lynch G Mir LM Oddone PJ Orimoto TJ Pripstein M Roe NA Ronan MT Wenzel WA Barrett M Ford KE Harrison TJ Hart AJ Hawkes CM Morgan SE Watson AT Goetzen K Held T 《Physical review letters》2007,98(14):141801
Using 230.2 fb-1 of e+e- annihilation data collected with the BABAR detector at and near the peak of the Upsilon(4S) resonance, 489+/-55 events containing the pure leptonic decay Ds+-->micro;+numicro have been isolated in charm-tagged events. The ratio of partial widths Gamma(D+-->micro+numicro)/Gamma(Ds+-->phipi+) is measured to be 0.143+/-0.018+/-0.006 allowing a determination of the pseudoscalar decay constant fDs=(283+/-17+/-7+/-14) MeV. The errors are statistical, systematic, and from the Ds+-->phipi+ branching ratio, respectively. 相似文献
150.
Aubert B Bona M Boutigny D Couderc F Karyotakis Y Lees JP Poireau V Tisserand V Zghiche A Grauges E Palano A Chen JC Qi ND Rong G Wang P Zhu YS Eigen G Ofte I Stugu B Abrams GS Battaglia M Brown DN Button-Shafer J Cahn RN Charles E Gill MS Groysman Y Jacobsen RG Kadyk JA Kerth LT Kolomensky YG Kukartsev G Lopes Pegna D Lynch G Mir LM Orimoto TJ Pripstein M Roe NA Ronan MT Wenzel WA Del Amo Sanchez P Barrett M Ford KE Harrison TJ Hart AJ Hawkes CM Watson AT Held T Koch H Lewandowski B 《Physical review letters》2007,98(6):061803
A search for lepton flavor violating decays of the tau lepton to a lighter mass lepton and a pseudoscalar meson has been performed using 339 fb;{-1} of e;{+}e;{-} annihilation data collected at a center-of-mass energy near 10.58 GeV by the BABAR detector at the SLAC PEP-II storage ring. No evidence of a signal has been found, and upper limits on the branching fractions are set at the 10;{-7} level. 相似文献