排序方式: 共有192条查询结果,搜索用时 15 毫秒
81.
Chen KF Hou WS Shapkin M Sokolov A Adachi I Aihara H Arinstein K Aulchenko V Aushev T Bakich AM Balagura V Bay A Belous K Bhardwaj V Bitenc U Bondar A Bozek A Bracko M Brodzicka J Browder TE Chang P Chao Y Chen A Chen WT Chistov R Choi Y Dalseno J Danilov M Dash M Drutskoy A Eidelman S Gabyshev N Golob B Ha H Haba J Hayasaka K Hayashii H Hazumi M Heffernan D Hoshi Y Hsiung YB Hyun HJ Iijima T Inami K Ishikawa A Ishino H Itoh R Iwasaki M Iwasaki Y Kah DH Kang JH Kapusta P Katayama N Kawai H 《Physical review letters》2008,100(11):112001
We report the first observation of e;{+}e;{-}-->Upsilon(1S)pi;{+}pi;{-}, Upsilon(2S)pi;{+}pi;{-}, and first evidence for e;{+}e;{-}-->Upsilon(3S)pi;{+}pi;{-}, Upsilon(1S)K+K-, near the peak of the Upsilon(5S) resonance at sqrt[s] approximately 10.87 GeV. The results are based on a data sample of 21.7 fb;{-1} collected with the Belle detector at the KEKB e;{+}e;{-} collider. Attributing the signals to the Upsilon(5S) resonance, the partial widths Gamma(Upsilon(5S)-->Upsilon(1S)pi;{+}pi;{-})=0.59+/-0.04(stat)+/-0.09(syst) MeV and Gamma(Upsilon(5S)-->Upsilon(2S)pi;{+}pi;{-})=0.85+/-0.07(stat)+/-0.16(syst) MeV are obtained from the observed cross sections. These values exceed by more than 2 orders of magnitude the previously measured partial widths for dipion transitions between lower Upsilon resonances. 相似文献
82.
Mizuk R Abe K Abe K Aihara H Akatsu M Asano Y Aulchenko V Aushev T Bakich AM Balagura V Ban Y Banerjee S Bedny I Bitenc U Bizjak I Blyth S Bondar A Bozek A Bracko M Brodzicka J Browder TE Chao Y Chen A Cheon BG Chistov R Choi SK Choi Y Chuvikov A Cole S Dalseno J Danilov M Dash M Dragic J Drutskoy A Eidelman S Fratina S Gabyshev N Garmash A Gershon T Gokhroo G Haba J Hastings NC Hayasaka K Hayashii H Hazumi M Hokuue T Hoshi Y Hou S Hou WS Hsiung YB Iijima T Imoto A Inami K Ishikawa A Itoh R 《Physical review letters》2005,94(12):122002
We report the observation of an isotriplet of excited charmed baryons, decaying into Lambda(+)(c)pi(-), Lambda(+)(c)pi(0), and Lambda(+)(c)pi(+). We measure the mass differences M(Lambda(+)(c)pi)-M(Lambda(+)(c)) and widths to be 515.4(+3.2+2.1)(-3.1-6.0) MeV/c(2), 61(+18+22)(-13-13) MeV for the neutral state; 505.4(+5.8+12.4)(-4.6-2.0) MeV/c(2), 62(+37+52)(-23-38) MeV for the charged state; and 514.5(+3.4+2.8)(-3.1-4.9) MeV/c(2), 75(+18+12)(-13-11) MeV for the doubly charged state, where the uncertainties are statistical and systematic, respectively. These results are obtained from a 281 fb(-1) data sample collected with the Belle detector near the Upsilon(4S) resonance, at the KEKB asymmetric energy e(+)e(-) collider. 相似文献
83.
Saigo M Abe K Abe K Aihara H Akatsu M Asano Y Aulchenko V Aushev T Bahinipati S Bakich AM Ban Y Banerjee S Bedny I Bitenc U Bizjak I Blyth S Bondar A Bozek A Bracko M Brodzicka J Browder TE Chao Y Chen A Chen KF Chen WT Cheon BG Chistov R Choi SK Choi Y Choi YK Chuvikov A Cole S Dalseno J Danilov M Dash M Dong LY Drutskoy A Eidelman S Eiges V Enari Y Fratina S Gabyshev N Garmash A Gershon T Gokhroo G Golob B Haba J Hayasaka K Hayashii H Hazumi M Higuchi T Hinz L Hokuue T Hoshi Y Hou S Hou WS 《Physical review letters》2005,94(9):091601
We report a study of the suppressed decays B--->[K(+)pi(-)](D)K- and B--->[K(+)pi(-)](D)pi(-), where [K(+)pi(-)](D) indicates that the K+pi(-) pair originates from a neutral D meson. These decay modes are sensitive to the unitarity triangle angle varphi(3). We use a data sample containing 275 x 10(6) BB pairs recorded at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric e(+)e(-) storage ring. The signal for B--->[K(+)pi(-)](D)K- is not statistically significant, and we set a limit r(B)<0.27 at 90% confidence level, where r(B) is the magnitude of the ratio of amplitudes |A(B--->D 0K-)/A(B--->D0K-)|. We observe a signal with 6.4sigma statistical significance in the related mode, B--->[K(+)pi(-)](D)pi(-). 相似文献
84.
Zhang J Abe K Abe K Abe T Aihara H Asano Y Aulchenko V Aushev T Aziz T Bahinipati S Bakich AM Bay A Bedny I Bitenc U Bizjak I Blyth S Bondar A Bozek A Bracko M Browder TE Chang P Chao Y Chen KF Cheon BG Chistov R Choi SK Choi Y Chuvikov A Danilov M Dash M Dong LY Dragic J Drutskoy A Eidelman S Eiges V Enari Y Fratina S Gabyshev N Garmash A Gershon T Gokhroo G Golob B Hayashii H Hazumi M Higuchi T Hinz L Hokuue T Hoshi Y Hou WS Hsiung YB Iijima T Imoto A Inami K Ishikawa A Ishino H Itoh R 《Physical review letters》2005,94(3):031801
We report a measurement of the branching fraction for the decay B+ --> rho(+) pi(0) based on a 140 fb(-1) data sample collected with the Belle detector at the KEKB asymmetric e(+)e(-) collider. We measure the branching fraction B(B(+) --> rho(+)pi(0)) = (13.2 +/- 2.3(stat)(+1.4)(-1.9)(syst)) x 10(-6), and the CP-violating asymmetry A(CP)(B-/+ -->rho(-/+)pi(0))=0.06 +/- 0.17(stat)(+0.04)(-0.05)(syst). 相似文献
85.
Dr. Shunpei Nobusue Hirokazu Miyoshi Dr. Akihiro Shimizu Dr. Ichiro Hisaki Kotaro Fukuda Prof. Masayoshi Nakano Prof. Yoshito Tobe 《Angewandte Chemie (International ed. in English)》2015,54(7):2090-2094
A tetramesityl derivative of hitherto unknown tetracyclopenta[def,jkl,pqr,vwx]tetraphenylene (TCPTP), which is a potential tetraradicaloid hydrocarbon, was synthesized. Theoretical calculations based on spin‐flip time‐dependent density functional theory predict that the closed‐shell D2h form of TCPTP is more stable than the open‐shell D4h form with its slightly tetraradical character. The tetramesityl derivative (Mes)4‐TCPTP exhibits remarkable antiaromaticity as a result of the peripheral 20‐π‐electron circuit, which causes an absorption maximum at a long wavelength and a small HOMO–LUMO gap. In solution, (Mes)4‐TCPTP most likely adopts rapidly equilibrating D2h structures that interconvert via the D4h transition state. X‐ray crystallographic analysis showed (Mes)4‐TCPTP as an approximate D2h structure. 相似文献
86.
Hiroto S Hisaki I Shinokubo H Osuka A 《Journal of the American Chemical Society》2008,130(48):16172-16173
Oxidation of 2,18-diborylporphyrin provided 2,18-dihydroxyporphyrin, which shows solvent-dependent keto-enol tautomerism and dimerization through hydrogen bonding interaction in solution. Further oxidation of 2,18-dihydroxyporphyrins afforded doubly and directly linked dioxoisobacteriochlorin face-to-face dimers. 相似文献
87.
Hisaki Otani Sakiko Fujita Yu Watanabe Michiya Fujiki Kotohiro Nomura 《Macromolecular Symposia》2010,293(1):53-57
Summary: Precise syntheses of soluble star polymers containing a sugar residue could be attained by adopting sequential ring-opening metathesis polymerizations of norbornene, 1,4,4a,5,8,8a-hexahydro-1,4,5,8-exo-endo-dimethanonaphtalene, and then 1,2:3,4-di-O-isopropylidene-α-D-galacto-pyranos-6-O-yl 5-norbornene-2-carboxylate using Mo(CHCMe2Ph)(N-2,6-iPr2C6H3)(OtBu)2. The resultant polymers possessed uniform molecular weight distributions, and the Mn values could be varied by the monomer/Mo molar ratios; their spherical images were observed in the TEM micrographs. 相似文献
88.
3,5-Ethenoporphyrin is a π-extended porphyrin containing a fused ethene unit between the meso- and β-positions, exhibiting unique contribution of macrocyclic antiaromaticity. We have recently reported that its analogue, etheno-fused diporphyrin, underwent thermal [2 + 2] cycloaddition to furnish X-shaped cyclobutane-linked tetraporphyrins. Here we demonstrate that the cyclobutane-ring formation is dynamically redox-active. Namely, the tetraporphyrin underwent two-step four-electron oxidation to afford two etheno-fused diporphyrin dications. The reduction of the resulting dication regenerated the cyclobutane-linked tetraporphyrin. The dication was sufficiently stable to allow its isolation under ambient conditions. The structure of the dication has been confirmed by 1H NMR spectroscopy and X-ray diffraction analysis. Importantly, the simultaneous double C–C bond cleavage in the cyclopropane ring in the tetraporphyrin is exceptional among dynamic redox (dyrex) systems to achieve large structural changes, thus offering new insights for the design of novel redox-active functional organic materials for electrochromic dyes, organic batteries, and organic memories.A four-electron oxidation of an X-shaped tetraporphyrin affords stable etheno-fused diporphyrin dications through double C–C bond cleavage. The reduction of the dication recovers the tetraporphyrin via a thermal [2 + 2] cycloaddition. 相似文献
89.
Hinoue T Shigenoi Y Sugino M Mizobe Y Hisaki I Miyata M Tohnai N 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(15):4634-4643
The construction and precise control of the face-to-face π-stacked arrangements of anthracene fluorophores in the crystalline state led to a remarkable red shift in the fluorescence spectrum due to unprecedented excited oligomer formation. The arrangements were regulated by using organic salts including anthracene-1,5-disulfonic acid (1,5-ADS) and a variety of aliphatic amines. Because of the smaller number of hydrogen atoms at the edge positions and the steric effect of the sulfonate groups, 1,5-ADS should prefer face-to-face π-stacked arrangements over the usual edge-to-face herringbone arrangement. Indeed, as the alkyl substituents were lengthened, the organic salts altered their anthracene arrangement to give two-dimensional (2D) edge-to-face and end-to-face herringbone arrangements, one-dimensional (1D) face-to-face zigzag and slipped stacking arrangements, a lateral 1D face-to-face arrangement like part of a brick wall, and a discrete monomer arrangement. The monomer arrangement behaved as a dilute solution even in the close-packed solid state to emit deep blue light. The 1D face-to-face zigzag and slipped stacking of the anthracene fluorophores caused a red shift of 30-40?nm in the fluorescence emission with respect to the discrete arrangement, probably owing to ground-state associations. On the other hand, the 2D end-to-face stacking induced a larger red shift of 60?nm, which is attributed to the excimer fluorescence. Surprisingly, the brick-like lateral face-to-face arrangement afforded a remarkable red shift of 150?nm to give yellow fluorescence. This anomalous red shift is probably due to excited oligomer formation in such a lateral 1D arrangement according to the long fluorescence lifetime and little shift in the excitation spectrum. The regulation of the π-stacked arrangement of anthracene fluorophores enabled the wide modulation of the fluorescence and a detailed investigation of the relationships between the photophysical properties and the arrangements. 相似文献
90.
Hisaki I Sasaki T Sakaguchi K Liu WT Tohnai N Miyata M 《Chemical communications (Cambridge, England)》2012,48(16):2219-2221
A universal method to determine handedness of 2(1) helical assemblies composed of planar aromatic molecules is proposed and demonstrated by taking P2(1)/c and Pbca crystals of benzene, the simplest aromatic molecule, as examples. 相似文献