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71.
The semileptonic decay width of heavy baryons such as (Λ
b
→ Λcev) has been estimated in the framework of a nonrelativistic field theoretic quark model where four component quark field
operators along with a harmonic oscillator wave function are used to describe translationally invariant hadronic states. The
present estimation does not make an explicit use of heavy quark symmetry and has a reasonable agreement with the experimentally
measured decay width, polarisation ratio and form factors with the harmonic oscillator radii and quark momentum distribution
inside the hadron as free parameters. 相似文献
72.
Egiyan KS Asryan G Gevorgyan N Griffioen KA Laget JM Kuhn SE Adams G Amaryan MJ Ambrozewicz P Anghinolfi M Audit G Avakian H Bagdasaryan H Baillie N Ball JP Baltzell NA Barrow S Batourine V Battaglieri M Bedlinskiy I Bektasoglu M Bellis M Benmouna N Berman BL Biselli AS Blaszczyk L Bouchigny S Boiarinov S Bradford R Branford D Briscoe WJ Brooks WK Bültmann S Burkert VD Butuceanu C Calarco JR Careccia SL Carman DS Cazes A Chen S Cole PL Collins P Coltharp P Cords D Corvisiero P Crabb D Crede V 《Physical review letters》2007,98(26):262502
The reaction 2H(e,e'p)n has been studied with full kinematic coverage for photon virtuality 1.75NN transition is the primary contribution at higher momenta. 相似文献
73.
S. Sankar MR. Manikandan S.D. Gopal Ram T. Mahalingam G. Ravi 《Journal of Crystal Growth》2010,312(19):2729-2733
The microbial free single crystals of α and γ glycine were grown from gel at room temperature in a new chemical route. These crystals showed a superior quality than the solution grown crystals. The metastable α-form and the stable γ-form of glycine were crystallized in silica gel by solubility reduction method. The form of crystallization is confirmed by single crystal and powder X-ray diffraction analyses. The crystals of α and γ glycine were found to crystallize in monoclinic and hexagonal crystal systems, respectively. For analyzing the functional group and thermal stability of α and γ glycine crystals, spectroscopic and thermal analyses have been carried out. The dielectric studies were performed to find the dielectric constant of the grown crystals and the results are discussed. Second harmonic generation efficiency of the crystal was measured by Kurtz’s powder method using Nd:YAG laser and it was found to be 2.68 times that of potassium dihydrogen phosphate crystals. 相似文献
74.
Carman JC 《The Journal of the Acoustical Society of America》2012,131(3):2401-2404
A tabletop apparatus permitting demonstrations and hands-on student exercises in the acoustic beamforming of linear arrays is described. The apparatus can be used to demonstrate how interference effects from two or more linearly arranged sources produce patterns of maxima and minima as described by theory. A transmitting array is attached to the top of a rotating table and a receiving transducer provides voltages to a signal processor. Students measure the angular speed of the rotating table and the voltages produced by the receiving transducer as a function of time. These data can be analyzed in a spreadsheet program and compared to theory. The angles at which signal maxima occur correspond well to theory and useful teaching discussions result from comparisons of signal maxima magnitudes. The spreadsheet analysis can also provide the students a graphical demonstration of l'H?pital's rule. 相似文献
75.
Baillie N Tkachenko S Zhang J Bosted P Bültmann S Christy ME Fenker H Griffioen KA Keppel CE Kuhn SE Melnitchouk W Tvaskis V Adhikari KP Adikaram D Aghasyan M Amaryan MJ Anghinolfi M Arrington J Avakian H Baghdasaryan H Battaglieri M Biselli AS Branford D Briscoe WJ Brooks WK Burkert VD Carman DS Celentano A Chandavar S Charles G Cole PL Contalbrigo M Crede V D'Angelo A Daniel A Dashyan N De Vita R De Sanctis E Deur A Dey B Djalali C Dodge G Domingo J Doughty D Dupre R Dutta D Ent R Egiyan H 《Physical review letters》2012,108(14):142001
We report on the first measurement of the F(2) structure function of the neutron from the semi-inclusive scattering of electrons from deuterium, with low-momentum protons detected in the backward hemisphere. Restricting the momentum of the spectator protons to ?100 MeV/c and their angles to ?100° relative to the momentum transfer allows an interpretation of the process in terms of scattering from nearly on-shell neutrons. The F(2)(n) data collected cover the nucleon-resonance and deep-inelastic regions over a wide range of Bjorken x for 0.65
相似文献
76.
77.
P. C. Carman 《Journal of solution chemistry》1978,7(11):845-858
In a recent derivation of relaxation effects in the Debye-Hückel-Onsager theory of electrolyte conductance, with a length parameter a, terms are included which have been omitted in earlier treatments (see Appendix). The new expression was applied earlier in a reanalysis of conductance data for aqueous solutions and is applied here to solutions in acetonitrile and in formamide, representing respectively dielectric constants considerably lower and higher than water. As in aqueous solutions, a minimum standard deviation is found over a wide range of (K
A,a) pairs without much effect on A
0
, so that only approximate determinations ofK
A are possible. On the whole, the most appropriate length parametera is the physical contact distance between counterions, not a fixed radius, independent of ionic size, such as the Bjerrum value, nor a much larger radiusR serving as a boudary between free and associated ions in the ionic atmosphere about a central ion. Relaxation effects calculated by the new analysis are smaller than those from previous expressions for equal values ofa, and this leads to considerably larger values ofK
A than in the original papers. As a consequence, specific short-range ion-ion and ion-solvent forces in most solutions predominate over electrostatic attraction between counterions in their contribution toK
A. A table of limiting equivalent conductance based on the A
0
values obtained is presented; this differs little from previous tables since A
0
values obtained by the new analysis are similar to those obtained originally. 相似文献
78.
Raman and resonance-Raman spectra of the I?3 ion isolated within CsI crystals have been studied using 647 nm and 488 nm exciting radiation. Sample temperatures between 300 and 20 K have been used. Eleven overtones of the symmetric stretching mode (nν1) have been observed in the resonance-Raman spectrum excited by the 488 nm Ar+ laser line. Bands centred at 153, 170, 264 and 304 cm?1 have been assigned as ν3, 2ν2, ν1+ν3 and 2ν3(Σ+) respectively. The remaining structure between the nν1 lines has been assigned as due to combinations of these lines with the lattice vibrations of the CsI crystal. 相似文献
79.
80.
In this paper exact asymptotic formulae are found for singularvalues of the Cauchy operator and the logarithmic potentialtype operator (on a bounded domain), as well as their productswith Bergman's projection. It is shown that these spectral characteristicsdetect geometric properties of a domain (area and the lengthof the boundary). The hypothesis "can we hear the shape of adrum", from a paper by J.M. Anderson, D. Khavinson, and V. Lomonosov[Spectral properties of some integral operators arisingin potential theory, Quart. J. Math. Oxford (2) 43 (1992)387-407], is correct in the above sense. 1991 Mathematics SubjectClassification: 47B10. 相似文献