共查询到20条相似文献,搜索用时 62 毫秒
1.
R. Lawall J. Barth C. Bennhold K. -H. Glander S. Goers J. Hannappel N. Jöpen F. Klein E. Klempt T. Mart D. Menze M. Ostrick E. Paul I. Schulday W. J. Schwille F. W. Wieland C. Wu 《The European Physical Journal A - Hadrons and Nuclei》2005,24(2):275-285
The reaction p K0+ was measured in the photon energy range from threshold up to 2.6 GeV with the SAPHIR detector at the electron stretcher facility, ELSA, in Bonn. Results are presented on the reaction cross-section and the polarization of the + as a function of the kaon production angle in the centre-of-mass system, cosc.m.K, and the photon energy. The cross-section is lower and varies less with photon energy and kaon production angle than that of p K+0. The + is polarized predominantly at cosc.m.K 0. The data presented here are more precise than previous ones obtained with SAPHIR and extend the photon energy range to higher values. They are compared to isobar model calculations. 相似文献
2.
《Czechoslovak Journal of Physics》1991,41(4):297-306
In this paper we present the results of a search for the charmed strange baryon
c
+
in the final states 0++K– and –++. The experiment was performed using the magnetic spectrometer BIS-2 with a hydrogen target located in the neutron beam of the Serpukhov accelerator. A narrow peak in the 0++K– state is observed at a mass of 2440 and possibly also of 2310 MeV/c2, corresponding to signals for the
c
+
0++K– and
c
+
0++K– (0 0) decays respectively. The statistics obtained for the –++ state is too low to make any conclusion.We are grateful to K. Hiller, F. Mandl, M. Markytan and J.MacNaughton for useful discussions and valuable remarks. 相似文献
3.
M. Büscher V. Koptev M. Nekipelov Z. Rudy H. Ströher Yu. Valdau S. Barsov M. Hartmann V. Hejny V. Kleber N. Lang I. Lehmann S. Mikirtychiants H. Ohm 《The European Physical Journal A - Hadrons and Nuclei》2004,22(2):301-317
The production of K+-mesons in pA (A = D, C, Cu, Ag, Au) collisions has been investigated at the COoler SYnchrotron COSY-Jülich for beam energies Tp = 1.0-2.3 GeV. Double differential inclusive pC cross-sections at forward angles {K^+} < 12° as well as the target mass dependence of the K+ momentum spectra have been measured with the ANKE spectrometer. Far below the free NN threshold at TNN = 1.58 GeV the spectra reveal a high degree of collectivity in the target nucleus. From the target mass dependence of the cross-sections at higher energies, the repulsive in-medium potential of the K+-mesons can be deduced. Using pN cross-section parameterisations from the literature and our measured pD data we derive a cross-section ratio (pnK+X)/(ppK+X) (3-4). 相似文献
4.
V. N. Fetisov L. Majling J. Žofka R. A. Eramzhyan 《Czechoslovak Journal of Physics》1986,36(3):451-454
The applicability of (K
–,–) - and (K
–,–
N)-reactions on13,14C and14,15N nuclei to the study of -transitions in primary and daughter -hypernuclei is discussed. The intensity of -deexcitation of
13C state |S
12C(15·11 MeV; 1+1): 1/2+ has been shown to be comparable with the intensity of baryon decay. Isospin selection rules are used to distinguish excitation energy ranges of primary hypernuclei, where the identification of the secondary -lines is probable.Presented at the symposium Mesons and Light Nuclei, Bechyn, Czechoslovakia, May 27–June 1, 1985. 相似文献
5.
G. P. Kamuntavičius D. Germanas R. K. Kalinauskas S. Mickevičius R. Žemaičinienė 《The European Physical Journal A - Hadrons and Nuclei》2005,25(3):379-385
The production of K+-mesons in proton-nucleus collisions from 1.0 to 2.3 GeV is analyzed with respect to one-step nucleon-nucleon (NN NYK+) and two-step -nucleon (N K+YN) or pion-nucleon (N K+Y) production channels on the basis of a coupled-channel (CBUU) transport approach including the kaon final-state-interactions (FSI). Momentum-dependent potentials for the nucleon, hyperon and kaon in the final state are included as well as K+ elastic rescattering in the target nucleus. The transport calculations are compared to the experimental K+ spectra taken at COSY-Jülich. Our systematic analysis of K+ spectra from 12C, 63Cu, 107Ag and 197Au targets as well as their momentum differential ratios gives a repulsive K+ potential of 20±5 MeV at normal nuclear matter density. 相似文献
6.
F. N. Gygax A. Hintermann W. Rüegg A. Schenck W. Studer A. J. van der Wal L. Schlapbach 《Hyperfine Interactions》1983,15(1-4):533-536
The + Knight shift in Platinum has been measured between 20 K and 785 K. It shows a strong temperature dependence and scales with the magnetic bulk susceptibility. A temperature independent contribution of +53±15 ppm and a d-electron induced hyperfine field per unpaired d-electron per atom of B
hfd
a
=–5.03 kG(±8.5%) are obtained. The + Knight shift in PdH0.70, PdH0.75 and PdH0.86 shows no dependence on temperature between 20 K and RT and increases from K=–(8±3) ppm for x=0.70 to K =+(6.5±3) ppm K=+(6.5±3) ppm for x=0.86, in good agreement with proton Knight shift measurements. 相似文献
7.
F. C. Hoh 《International Journal of Theoretical Physics》2000,39(4):1069-1084
An expression for the decay rate (0 ) has been derived in the frameworkof the spinor strong interaction theory, a first-principles strong interaction theoryproposed some years ago as an alternative to low-energy QCD. The startingpoint is the SO(3) gauge-invariant action for two quark mesons which has beensuccessful in accounting for confinement, + + , e+, and 0 e+, nonexistenceof the Higgs boson, and other low-energy mesonic phenomena. The quasi-four-quarkmeson equations developed for the decay of a vector meson into twopseudoscalar mesons V PP has been taken over here to apply to P(0) VV(+ –) (plus + and – which annihilate each other). This mechanismin principle agrees with that of the assumption of vector meson dominance inthe literature. It, together with the effect of form factors, arises naturally in theformalism and need not be assumed. Equations for the perturbed vector mesonwave functions cannot be simply solved and an assumption has been made toobtain an estimate of their magnitude. Together with a constant associated withthe strong coupling obtained earlier from V() PP(K+K–), the estimated decayrate is 19.2 eV, in order-of-magnitude agreement with data (7.74 eV). 相似文献
8.
We study kaonic deuterium, the bound K-d state AK d. Within a quantum field-theoretic and relativistic covariant approach we derive the energy level displacement of the ground state of kaonic deuterium in terms of the amplitude of K-d scattering for arbitrary relative momenta. Near threshold our formula reduces to the well-known DGBT formula. The S-wave amplitude of K-d scattering near threshold is defined by the resonances (1405), (1750) and a smooth elastic background, and the inelastic channels K-d NY and K-d NY, where Y = ±,{0} and {0}, where the final-state interactions play an important role. The Ericson-Weise formula for the S-wave scattering length of K-d scattering is derived. The total width of the energy level of the ground state of kaonic deuterium is estimated using the theoretical predictions of the partial widths of the two-body decays AKd NY and experimental data on the rates of the NY pair production in the reactions K-d NY. We obtain {1s} = (630±100)eV. For the shift of the energy level of the ground state of kaonic deuterium we predict {1s} = (325±60)eV. 相似文献
9.
F. C. Hoh 《International Journal of Theoretical Physics》1998,37(6):1693-1705
From an isospin SU(2) × hypercharge U(1)gauge-invariant meson action for K+,+ +, a prediction ofthe Cabbibo angle was obtained earlier. Using anotherresult of the spinor strong interaction theory that the s quark is only a littleheavier than the d quark, the above action can beextended to a weakly broken SU(3) one. The Weinbergangle is found to be 30° in the limit of this SU(3)symmetry. In the approximation and context entailing thislimit, the Weinberg angle can be removed from the listof undetermined fundamental parameters in electroweaktheory. The spinor strong interaction Lagrangian used above and applied to the decay+ e+ is shown tohold for + 0e+ as well, renderingthe conserved vector current hypothesis hithertorequired to account for the latter decaysuperfluous. 相似文献
10.
T. M. Aliev N. A. Guliev I. G. Dzhafarov F. T. Khalil-Zade 《Russian Physics Journal》1981,24(2):159-163
On the basis of an arbitrary (V, A) structure of the neutral weak ¯ee and LL currents (L=–, M0) a study is made of the processes of production in colliding electron-positron beams of pairs of heavy leptons with subsequent decays in accordance with the schemes e+e––(µ–vµv) + +( anything) and e+e–M0(µ–e+ve) + M0( anything). The energy spectrum and asymmetry of the distribution of the produced muons are investigated.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 66–70, February, 1981. 相似文献
11.
We report preliminary experiments which demonstrate the simultaneous detection of both atomic and molecular hydrogen using a single tunable ArF laser. The tunable ArF laser was modified to lase simultaneously at two wavelengths by the addition of a second grating to the oscillator stage as in earlier work by Ketterle et al. for KrF operation. To our knowledge, this is the first demonstration of dual-wavelength capability with a tunable ArF excimer. The H atom diagnostic utilized tunable ArF excimer laser output at 193.29 nm which was Raman shifted in D2 (first Stokes) to generate 205.14 nm radiation which then excited the H atom to its (3s, 3d) states via a two-photon transition. Fluorescence was detected at 656 nm on the (3s, 3d) 2p transition. The second wavelength from the tunable excimer was used to excite several rovibronic LIF transitions of hydrogen molecule via two-photon absorption on the E
1
g
+
X
1
g
+
(2,0) band. Fluorescence occurs at 750 nm and 830 nm on the (E
1
g
+
B
1
g
+
) transitions. 相似文献
12.
Gianfausto Dell'Antonio Andrea Posilicano 《Communications in Mathematical Physics》1991,141(3):559-576
Let t,
t
n
,n1, be solutions of Schrödinger equations with potentials form-bounded by –1/2 and initial data inH
1(
d
). LetP, P
n
,n1, be the probability measures on the path space =C(+,
d
) given by the corresponding Nelson diffusions. We show that if {
t
n
}
n1 converges to t inH
1(
d
), uniformly int over compact intervals, then converges to in total variation t0. Moreover, if the potentials are in the Kato classK
d
, we show that the above result follows fromH
1-convergence of initial data, andK
d
-convergence of potentials. 相似文献
13.
The body frame fixed nuclei and the laboratory frame rotational close coupling approximations have been employed to calculate electronic excitation of H2 (X1
g
+
B1
u
+
) by positron impact. Two electronic states (X1
g
+
and B1
u
+
) and three rotational states in both the elastic and excitation channels are retained in the calculations. Results are reported for electronically elastic, excitation and rotational cross sections up to the incident energy 75.0 eV. The elastic cross sections are found to be influenced significantly with the addition of B1
u
+
state in the expansion scheme, in both the models used. Above the incident energy of 25.0 eV, the electronic excitation cross sections using the laboratory frame differ significantly from those of the fixed nuclei model. 相似文献
14.
We reconsider the problem of the Hamiltonian interpolation of symplectic mappings. Following Moser's scheme, we prove that for any mapping , analytic and -close to the identity, there exists an analytic autonomous Hamiltonian system, H such that its time-one mapping H differs from by a quantity exponentially small in 1/. This result is applied, in particular, to the problem of numerical integration of Hamiltonian systems by symplectic algorithms; it turns out that, when using an analytic symplectic algorithm of orders to integrate a Hamiltonian systemK, one actually follows exactly, namely within the computer roundoff error, the trajectories of the interpolating Hamiltonian H, or equivalently of the rescaled Hamiltonian K=-1H, which differs fromK, but turns out to be 5 close to it. Special attention is devoted to numerical integration for scattering problems. 相似文献
15.
F. Botterweck M. Charlet P. V. Chliapnikov A. De Roeck E. A. De Wolf K. Dziunikowska P. E. Ermolov A. Eskreys Z. C. Garutchava G. Gulkanyan R. Sh. Hakobyan T. Haupt K. Kaleba W. Kittel D. Kisielewska A. B. Michalowska V. I. Nikolaenko K. Olkiewicz V. M. Ronjin A. G. Tomaradze F. Verbeure R. Wischnewski S. A. Zotkin 《Zeitschrift fur Physik C Particles and Fields》1992,55(3):373-382
Data are presented on inclusiveK
s
0
and production inK
+ and + collisions with Al and Au nuclei at 250 GeV/c. Results are given on total inclusive cross sections and theA dependence, as well as on distributions in Feynman-x
F
, rapidityy and transverse momentum. Ratios ofK
S
0
and of to + production are presented. The data are compared with predictions of the quark-parton model FRITIOF. 相似文献
16.
A. A. Gogolin 《Zeitschrift für Physik B Condensed Matter》1985,58(3):205-211
The averaged retarded electron Green functionG
+(,k) in 1d disordered metal is calculated using the Berezinsky diagram technique. Using the Gorkov's theory it is shown, that the substitution of inG
+ (,k) by the square of the external frequency atk=0 gives the dependence of Fröhlich conductivity F(). This dependence describes the impurity pinning of CDW in 1d disordered metals. The good agreement of this dependence with experimental data Zeller et al. about F() in quasi-1d conductor KCP is found 相似文献
17.
G. R. Sudhakaran J. C. Sarker R. L. Bhattacharjee L. H. Johnston I. Mukhopadhyay R. M. Lees 《International Journal of Infrared and Millimeter Waves》1990,11(4):505-517
Laser Stark spectra have been observed for CD3OH and13CH3OH using the 311 m line of the HCN laser. The spectra were taken for both parallel and perpendicular polarizations up to 60,000 Volts/cm. For CD3OH, the two characteristic structures in the spectra have been identified as the JK=144133, A± doublet in the vt=0 torsional state. For13CH3OH, the low field structure observed is assigned as JK=153142, A– in the vt=0 torsional state. 相似文献
18.
Coherent vacuum ultraviolet (VUV) radiation was generated by four-wave difference frequency mixing (VUV=21–2) of pulsed dye laser radiation in carbon monoxide (CO). The frequency 1 was tuned to the C
1+(=0)X
1+(=0) two-photon transition, while the dye laser frequency 2 was scaned around 17650 cm–1 which corresponds to the A
1(=7)«C
1+(=0) transition energy. The VUV intensity was found to be strongly wavelength dependent. The analysis of the spectrum revealed (i) that the VUV intensity was enhanced by the rotational levels of the A
1(=7) state and (ii) that the off-resonance excitation in the C
1+(=0)X
1+(=0) two-photon transition greatly contributed to the present four-wave mixing process. The effects of pumping laser detuning, saturation and foreign gases are briefly discussed. 相似文献
19.
We present a systematic approach to the calculation of finite-size (FS) effects for anO(n) field-theoretic model with both short-range (SR) and long-range (LR) exchange interactions. The LR exchange interaction decays at large distances as 1/r
d+2–2,0+,0+. Renormalization group calculations ind=d
u
– are performed for a system with a fully finite (block) geometry under periodic boundary conditions. We calculate the FS shift of the critical temperature and the FS renormalized coupling constant of the model to one-loop order. The universal scaling variable is obtained and the FS scaling hypothesis is verified. 相似文献
20.
LetT
0(, )+V be the Schrödinger operator corresponding to the classical HamiltonianH
0()+V, whereH
0() is thed-dimensional harmonic oscillator with non-resonant frequencies =(1, ... ,
d
) and the potentialV(q
1, ... ,q
d) is an entire function of order (d+1)–1. We prove that the algorithm of classical, canonical perturbation theory can be applied to the Schrödinger equation in the Bargmann representation. As a consequence, each term of the Rayleigh-Schrödinger series near any eigenvalue ofT
0(, ) admits a convergent expansion in powers of of initial point the corresponding term of the classical Birkhoff expansion. Moreover ifV is an even polynomial, the above result and the KAM theorem show that all eigenvalues
n
(, ) ofT
0+V such thatn coincides with a KAM torus are given, up to order , by a quantization formula which reduces to the Bohr-Sommerfeld one up to first order terms in . 相似文献