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1.
The average multiplicity in deep inelastic electro- and neutrinoproduction at large ω(ωs/Q2 + 1) is related in Feynman's version of the parton model to the average multiplicities in high-energy electron-positron annihilation and hadron-hadron scattering. The relation is: 〈n(s, Q2)〉ePP ~ Ce+e?ln(Q2M1⊥2) + Chln(ω ? 1), where Ce+e? and Ch are, respectively, the coefficients of ln(s/M1⊥2) in the multiplicities from e+-e? and P-P in to hadrons, and M1⊥ is an average transverse mass.  相似文献   

2.
If the hadronic contribution to vacuum polarization, which is proportional to the ration of e+e? annihilation into hadrons to that into μ+μ? rises asymptotically as a power β > 12 of the squared four-momentum, the ratio σ(e+e?→hadrons)σ point (σpoint = (4πα2)(3s)) is bound to be less than ?(3 tg πβ)(8α) and this limit is approached sooner for higher β. Other models of vacuum polarizations are also considered together with their possible origin and implications.  相似文献   

3.
The analysis of the reaction e+e?π+π? measured at the e+e? colliding beam machine ADONE shows that, if ?′ and ?″ exist, the cross sections compare as follows (taking the ? as the reference point): σ(e+e? → ? → π +π?): σ(e+e??′ → π+π?): σ(e+e??″ → π+π?) = 1: (7 ± 4) × 10?3: (1 ± 5) × 10?4. The square of the product of their couplings to the photon (γ?) and the γγ system (g?ππ) are derived.  相似文献   

4.
The QCD effective coupling constant αs(Q2) is determined by comparing the O(αs)2 jet-distributions with the high-energy e+e? data from PETRA. We get αs(Q2 = 1225 GeV2) = 0.125 ± 0.01, which corresponds to ΛMS = 110+70?50MeV with five flavours.  相似文献   

5.
For free and interacting Hamiltonians, H0 and H = H0 + V(r) acting in L2(R3, dx) with V(r) a radial potential satisfying certain technical conditions, and for ? a real function on R with ?′ > 0 except on a discrete set, we prove that the Moller wave operators
Ω± = strong limit eit?(H) e?it?(H0)
exist and are independent of ?. The scattering operator
S = (Ω+)1Ω?
is shown to be unitary. Our proof utilizes time independent methods (eigenfunction expansions) and is effective in cases not previously analyzed, e.g. V(r) = sinrr and many others.  相似文献   

6.
A weak emission spectrum of I2 near 2770 Å is reanalyzed and found to to minate on the A(1u3Π) state. The assigned bands span v″ levels 5–19 and v′ levels 0–8. The new assignment is corroborated by isotope shifts, band profile simulations, and Franck-Condon calculations. The excited state is an ion-pair state, probably the 1g state which tends toward I?(1S) + I+(3P1). In combination with other results for the A state, the analysis yields the following spectroscopic constants: Te = 10 907 cm?1, De = 1640 cm?1, ωe = 95 cm?1, R″e = 3.06 A?; Te = 47 559.1 cm?1, ωe = 106.60 cm?1, R′e = 3.53 A?.  相似文献   

7.
The predictions of perturbative QCD are derived in the deep euclidean region, whereas the physical region for most observables is timelike. The confrontation of these predictions with experiment thus necessitates an analytic continuation. This we find introduces large higher order corrections in terms of αs(|Q2|), the usual choice ofperturbative expansion parameter. These corrections are naturally absorbed by changing to the expansion parameter a(Q2) = |αs(Q2)|(Re αs(Q2)/|αs(Q2)|)(n?2)3, where αs(Q2)n is the leading term in the spacelike region. For the intermediate range of Q2 experimentally accessible at present, where a(Q2) is significantly smaller than αs(|Q2|), we find the resulting phenomenology is improved. In particular, we demonstrate how the values of ΛMS obtained from analyses of quarkonium decays become consistent.  相似文献   

8.
High-resolution (0.002 cm?1) stimulated Raman spectroscopy has been applied to the study of both normal and satellite Q branches of the fundamental vibrational band of molecular oxygen. Using a pulsed molecular free-expansion jet to adiabatically cool the oxygen sample, satellite Q branches at 1554 and 1558 cm?1 that arise due to the splitting of the 3Σg ground state by spin-spin and spin-rotation interactions were completely resolved for the first time. Measured intensity ratios for the ΔNΔJ(J, N) = Q0(2, 1) and QR(1, 1) lines, and for the QS(0, 1) and QP(2, 1) lines compare favorably with that for a coupling case intermediate between Hund's cases (a) and (b). Depolarization ratios, measured for a series of QQ-branch (unresolved) triplets, give a value 0.164 ± 0.004 for the depolarization ratio of the fundamental vibrational band.  相似文献   

9.
The hyperfine spectrum of KCl has been examined at near-zero electric field and zero magnetic field using a molecular beam electric resonance spectrometer. Rotational as well as vibrational shifts have been observed in both nuclear quadrupole interactions. With eqQ = Q00 + Q10(v + 12) + Q20(v + 12)2 + Q01J(J + 1), we find (all in units of kHz) for K in 39K35Cl: Q00 = ?5691.47 ± 0.04, Q10 = 51.32 ± 0.06, Q20 = ?0.205 ± 0.020, Q01 = 0.014 ± 0.007, Q00(K37Cl) ? Q00(K35Cl) = ?0.03 ± 0.07; for Cl in 39K35Cl: Q00 = 137.0 ± 0.3, Q10 = ?163.2 ± 0.5, Q20 = 1.57 ± 0.15, Q01 = 0.07 ± 0.03, [Q(35Cl)Q(37Cl)]Q00(K37Cl) ? Q00(K35Cl) = ?0.5 ± 0.6; and magnetic constants cK = 0.154 ± 0.007, cCl = 0.435 ± 0.010, c3 = 0.035 ± 0.012, and c4 = 0.009 ± 0.006. These have been used to provide a mapping of the field gradients at both nuclear sites to fourth order in ξ = (r ? re)re. We find eQqK(ξ) = (?5692.5 ± 2.5) + (1.7 ± 0.8) × 104ξ + (?2. ± 4.) × 104ξ2 + (?8. ± 18.) × 105ξ3 + (8. ± 15.) × 106ξ4 and eQqCl(ξ) = (120. ± 22.) + (8. ± 4.) × 104ξ + (?5.8 ± 2.0) × 105ξ2 + (?1.1 ± 1.6) × 107ξ3 + (1.1 ± 1.3) × 108ξ4.  相似文献   

10.
The 0-0, 1-1, 2-2, and 3-3 bands of the A2Π-X2Σ+ transition of the tritiated beryllium monohydride molecule have been observed at 5000 Å in emission using a beryllium hollow-cathode discharge in a He + T2 mixture. The rotational analysis of these bands yields the following principal molecular constants.
A2Π:Be = 4.192 cm?1; re = 1.333 A?
X2Σ:Be = 4.142 cm?1; re = 1.341 A?
ωe′ ? ωe″ = 16.36 cm?1; ωe′Xe′ ? ωe″Xe″ = 0.84 cm?1
From the pure electronic energy difference (EΠ - EΣ)BeT = 20 037.91 ± 1.5 cm?1 and the corresponding previously known values for BeH and BeD, the following electronic isotope shifts are derived
ΔEei(BeH?BeT) = ?4.7 ≠ 1.5cm1, ΔEei(BeH?BeT) = ?1.8 ≠ 1.5cm1
and related to the theoretical approach given by Bunker to the problem of the breakdown of the Born-Oppenheimer approximation.  相似文献   

11.
We suggest a simple definition of the topological charge density Q(x) in the lattice Yang-Mills theory and evaluate A≡∝d4xQ(x)Q(0)〉 in SU(2) by Monte Carlo simulation. The “data” interpolate well between the strong and weak coupling expansions, which we compute to order g?12 and g6, respectively. After subtraction of the perturbative tail, our points exhibit the expected asymptotic freedom behaviour giving A14≌(0.11±0.02)K12, K being the SU(2) quarkless string tension. Although a larger value for A14K?12 would be preferable, we are led to conclude (at least tentatively) that the UA(1) problem of QCD is indeed solved perturbatively in the quark loop expansion.  相似文献   

12.
Quantitative measurements of intensities and half-widths were made for individual rotational lines of the atmospheric oxygen B band. The total band intensity, as derived from the line intensity measurements, is 40·8±0·6 cm?1km?1atm?1 STP. As had been previously found in this laboratory for the oxygen A band, the relative line intensities conform closely to the rotational distribution calculated by either Schlapp or by Watson. The line half-widths at half-intensity were determined for oxygen self-broadening for the PQ and PP branch lines and for a few RQ and RR branch lines near the band origin, and were found to vary from 0·064 cm?1atm?1 at J′ = 1 to 0·042 cm?1atm?1 at J′ = 25.  相似文献   

13.
We point out that existing data on the resonance shape of ?? provide useful bounds on the B meson mass: M(??)? 2 M(B) = 9?6+12 MeV if one uses the quark pair creation model. From the upper limits on B1B + BB1 production one gets M(??) ? 2M(B) < 37 MeV. We show how measurements of inclusive semileptonic B decays allow us to determine the electromagnetic mass splitting M(B0) ? M(B?) without having to identify exclusive B decays. As byproducts one obtains information on the B0-B? lifetime ratio and on B0-B0 mixing.  相似文献   

14.
The Coriolis interactions between ν1 and ν3, and between ν2 and ν3 in SO2 have been analyzed to obtain the signs of the products ζ3.1c(a?Q3)(b?Q1) and ζ3.2c(a?Q3)(b?Q2). It has been found that both of the signs of these products are positive. Then, relative signs of (?Q1) have been determined using the calculated values of the Coriolis zeta constants for the present definition of the normal coordinates. The obtained sign combination of (?Qi) is ±(+?+), which agrees with the one predicted by the molecular orbital calculations. Using the sign combination (+?+), the polar tensors of S and O atoms were also calculated.  相似文献   

15.
We prove that the generalized eigenfunctions of the Schrödinger operator are continuous for potentials obeing the following assumptions: V=V+?V?,V±≥0,V+∈Lploc(Rl), V?∈Lp(Rl),p > l2.  相似文献   

16.
Let 0 ?q(x) ∈L1,loc(Rm),m? 1.Consider the operatorT0 = ?Δ+q with domain consisting of all bounded measurable functions u(x), x ∈ Rm, having bounded support, for which the distribution ?Δu+qu belongs to L2(Rm). The main result of the paper is essential self-adjointness of T0 in L2(Rm). The proof is independent of a method due to Kato who recently established the self-adjointness of a maximal Schrödinger operator corresponding to such potential.  相似文献   

17.
The difference of the cross sections for deep inelastic scattering of muons with average momenta 21 GeV/c with right and left helicity at large angles, i.e., with large momentum transfer, has been measured. No statistically-significant dependence of cross sections on the longitudinal polarization of muons has been found, i.e. no parity-nonconservation effects in deep inelastic μN interaction have been observed. The magnitude of the cross-section asymmetry R = [〈σR〉 ? 〈σL〉][〈σR〉+ + 〈σL〉] may be represented as R = βQ2〉 = (? 4 ± 6) × 10?3Q2, (GeV/c)2〉. The limitations Go(μ) = (+ 6 ± 10)G have been obtained for the constant Go(μ) of vector-axial interaction (Go(μ)2) [μγα(1 + γ5)μ] Jαo (hadron, V-A).  相似文献   

18.
The simplest four-quark SU(2) ? U(1) models with an anomally-free heavy lepton sector can have two charged heavy leptons and one or two neutral leprons. Such models also explain the rise in R (the ratio of hadronic to muon pair production in e+e? collisions). We study some consequences of different choices of leptonic numbers for L1 and L2. In particular, we derive, the leptonic decay width when several final-stae leptons are massive; the cross section for e+e?L1L2 production; the branching ratio for e+e?L2L2e3μ+missing energy.  相似文献   

19.
From the angular distributions of γ-rays emitted by oriented 129gTe and 129mTe nuclei implanted in iron by isotope separator, unique spin assignments could be made for the excited states of 129I at 487.4 keV (52+), 696.0 keV (112+), 729.6 keV (92+), 768.9 keV (72+), 1050.4 keV (72+) and 1111.8 keV (52+). In addition, E2/M1 amplitude ratios for the following 129I γ-rays (energies are in keV) are derived: δ(459.6) = ?(0.076+0.037?0.148); δ(487.4) = 0.50+0.17?0.10 or δ? = 0.35+0.15?0.09; δ(556.7) = 0.06±0.02 or δ? = ?(0.10±0.02); δ(624.4) = 0.10±0.26 or δ? > 0.4; the 696.0 keV γ-ray is pure E2; δ(729.6) = ?(0.34±0.06) or δ?1 = 0.55±0.05; δ(741.1) = ?(0.27±0.10) or δ?1 = ?(0.43±0.12); δ(817.2) = 0.46±0.04 or δ?1 =0.20±0.03 if Iπ (845 keV) = 72+; δ(1022.6) = ?(0.02 ±0.02) or δ?1 = ?(0.23±0.02); δ(1084) = 0.56 +0.04?0.14; δ(1111.8) = 0.06±0.05 or δ?1 = ?(0.08±0.05). The anisotropy of the 531.8 keV γ-ray excludes 12+ as a possible spin assignment for the 559.6 keV level, so that no 12+ level is fed in the decay from 129Te. Anisotropies for the 209, 250.7, 278.4 and 281.1 keV γ-rays are also measured. Comparison of the level scheme is made with theoretical predictions from both the pairing-plus-quadrupole model and the intermediate coupling unified model.  相似文献   

20.
A field theoretical model is proposed to describe the critical behaviour of a strongly inhomogeneous spin system with a position dependent concentration of magnetic atoms C(R) and magnetisation M(R). Assuming a finite number of n Fouriermodes CQvv = 1,..., n, to express C(R), the quenched randomness requires to interpret {Qv|Qv|2} on a set of invariant or marginal lengths. As consequence, M(R) can be described by n Fourier-modes MQv, where n ? n. For short range spin-spin interaction, we find for strong inhomogeneity, i.e. large n, the critical exponent between those of the related homogeneous system and those of the spherical model.  相似文献   

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