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1.
2.
Mohammad R. Ahmady Roberto R. Mendel 《Zeitschrift fur Physik C Particles and Fields》1995,65(2):263-265
The decay rates for the exclusiveB decaysBK
c
andBK*
c
are calculated in the context of the heavy quark effective theory. We obtain(BK
c
)/ (BK)=1.6±0.2 and(BK*
c
)/ (K*)=0.39±0.04. These results lead to estimates BR(BK
c
)=(0.11±0.02)% and BR(BK*
c
)=(0.05±0.01)% if we use the central current experimental values forB(K, K
*) branching ratios. 相似文献
3.
New measurements of the reactione
+
e
– confirm previous evidence for the decay1 and provide a strong constraint on the mass of the1. The results from a detailed analysis of these data are compared with those from a corresponding analysis of new data on the reactione
+
e
–. It is shown that
in accord with expectation. This identification of a strong1 decay supports a previous claim that the1 and theC(1480), observed in the channel, cannot be different manifestations of the same particle. 相似文献
4.
5.
G. M. Beladidze S. I. Bityukov G. V. Borisov Yu. P. Gouz R. I. Dzhelyadin Yu. M. Ivanyushenkov A. N. Karyukhin I. A. Kachaev G. A. Klyuchnikov V. F. Konstantinov M. E. Kostrikov V. V. Kostyukhin A. A. Kriushin Yu. A. Khoklov V. V. Lapin T. A. Lomtadze V. D. Matveyev V. A. Medovikov V. F. Obraztsov A. P. Ostankov D. I. Ryabchikov V. K. Semenov E. A. Starchenko N. A. Shalanda E. G. Tskhadadze N. K. Vishnevsky E. V. Vlasov V. I. Yakimschuk A. M. Zaitsev S. A. Zimin 《Zeitschrift fur Physik C Particles and Fields》1992,54(2):235-238
The reaction
–
C
–
C has been studied at 36 GeV/c. A clear signal for the decaya
2
–
(1320)
–
· is observed in the
–
mass spectrum. The measured ratio of branchings is BR (a
2
–
–
)/BR(a
2
–
–
);(3.4±0.8±0.5)·10–2. 相似文献
6.
N. Z. Akopov G. G. Arakelyan A. Ferrer A. A. Grigoryan G. N. Khachatryan V. F. Perepelitsa 《Zeitschrift fur Physik C Particles and Fields》1991,52(4):663-672
We analyze the available experimental data on the backward production processes N and N in the framework of the strong-cut Reggeized absorption model, which is based on the exchange of the baryon Regge trajectoriesN
and with the associated cuts. The model describes rather well the data on the differential cross sections at incident momenta ranging from 2.15 to 20 GeV/c. An essential contribution of exchange even at small energies (E
lab of the order of a few GeV) is found. A model-independent analysis of data confirms this fenomena. 相似文献
7.
Giancarlo D'Ambrosio Mario Miragliuolo Francesco Sannino 《Zeitschrift fur Physik C Particles and Fields》1993,59(3):451-456
We discuss the decayK
s
+– in the framework of chiral perturbation theory. The direct emission in this decay can be an useful test of meson dynamics. 相似文献
8.
We here compute the reaction G0 for various glueball candidatesG and their assumed quantum states, using a non-relativistic gluon bound-state model for the glueball. 相似文献
9.
The possible presence of hairpin diagrams is analyzed in th model-independent quark-diagram scheme for two-body decays of charmed mesons. Current experimental data do not require the presence of hairpin diagrams inDVP (V: vector meson,P: pseudoscalar meson), in accordance with the OZI rule. However, there is a possible indication that they are important in the decay ofDPP. The measurement ofD
s
+
+ is crucial to test the mechanism of hairpin diagrams. 相似文献
10.
Narrow dibaryon resonances observed in elastic and inelastic hadron scattering channels atM
NN
*
=1875–2300 MeV/c2 are characterized by the relative resolution (FWHM/M
pp
*
) 10–3 comparable to that provided by Ge(Li) detectors in the case of gamma-ray spectroscopy. The gamma-ray spectrum analysis codes GSAP, AUTSPAN and SAMPO-80 have been used to analyse the effective mass distributions of dibaryons from the reactions dp (pn) p, dp (pp) n, np pp–, and pppp studied at the Dubna synchrophasotron. The produced results suggest these codes to be reliable software tools in the new spectroscopic region of interest.On leave fromNuclear Physics Institute, Czechosl. Acad. Sci., 250 68 e near Prague, Czechoslovakia. 相似文献
11.
The positron lifetime and DSC measerments for EBBA and DOBAMBC have been made with heating and cooling clycles. The experimental results show that a shorter lifetime (1) is essentially independent of temperature while the longer lifetime (2) and the intensity (I
2) change abruptly double or triple with temperature. Consequently, the EBBA has only nematic phases while the DOBAMBC has two liquid-crystalline phases (smectic C* and smectic A) with transition temperatures as follows: for EBBA, solid nematic (304.5 K), nematic isotropic (356.5 K), isotropic nematic (356.5 K), nematic solid (301 K); and for DOBAMBC, solid smectic C* (346 K), smectic C* smectic A (357.5 K), smectic A isotropic (389 K). These critical temperatures are in accordance with the transition temperatures measured by DSC. In addition, the difference in the solid-nematic transition temperature in the heating and cooling cycles was also observed. A discussion about the correlation of the observed changes in lifetime (2) with the changes in molecular orientational order (S) and dielectric anisotropy () is presented. 相似文献
12.
A new procedure is devised to evaluate the proton form-factor at the ¯pp threshold from experimental data on ¯ppe
+
e
– annihilation at rest. Comparison of the ¯ppe
+
e
– and¯pp
+– processes reveals that annihilation ranges for various channels are ranked in line with quark dynamics.This work has been funded in part by the German Federal Minister for Research and Technology (BMFT) under the contract number 06HD756 相似文献
13.
We consider the CP-violating asymmetry betweenB
0f and
f in the case thatf is a CP-eigenstate containing no charmed quarks. The asymmetry is assumed to arise as a result of mixing with other channelsf having the same quantum numbers but containing ac
pair. Inelastic unitarity is implemented by means of the K-Matrix formalism, in which the constraints of CPT are manifestly satisfied. The formalism is applied to a hypothetical two-channel problemB
0M
,M
, and then to a realistic four-channel situationB
0
+
–,
0
0,D
+
D
–,D
0
0. Asymmetries and branching ratios are estimated for the decaysB
0
+
–,
0
0. 相似文献
14.
I. G. Aznauryan 《Zeitschrift fur Physik C Particles and Fields》1995,68(3):459-462
We show that photoproduction experiments provide propitious conditions to study the exotic state 1–+ in the and channels. For unpolarized photons contributions from natural and unnatural parity exchanges do not interfere with each other, a fact which permits to estimate the correctness of phase shift analyses. In photoproduction of the + system in the mass range ofa
2(1320) a more stringent limit on the product (1–+)Br(1–+) can be obtained than in experiments on Primakoff production on nuclei. Particularly favourable is the study of the state 1–+ in the coherent photoproduction of the 0 and 0 systems on nuclei, with significantly enlarged statistics and a simplified phase shift analysis. 相似文献
15.
The OZI suppressed reactions¯pp and¯pp are reanalyzed, evaluating the unitarity contributions from two meson intermediate states with full spin, partially correcting earlier results. An estimate for¯pp without spin is also given. Together with earlier VDM results for¯pp the conservative estimates reported here easily explain the observed rates for all the meson channels considered.It is a pleasure to thank the following colleagues for numerous discussions: C. Amsler, D. Buzatu, O. Gortchakov, F. Lev, J.-M. Richard and M.G. Sapozhnikov. 相似文献
16.
Nikolai N. Nikolaev Vladimir R. Zoller 《Zeitschrift fur Physik C Particles and Fields》1992,56(4):623-628
One expects a similarity of the energy dependence of the difference
tot(*p)–
tot(*n) for virtual (deep inelastic scatteringQ
2m
2) and real (Q
2=0) photons. Previous analysis of D structure functions with allowence for nuclear shadowing (NS) in the deuteron has led to conclusion that
tot(*p)–
tot(*n)<0>0>x<0.015. the=" early=" evidence=" from=" the=" real=" photoproduction=" data=">0.015.>
tot(p)–
tot(n)<0. we=" critically=" reexamine=" determinations=" of=" the=">0.>
tot(p)–
tot(n), using more accurate calculations of NS correction to
tot(D), and discuss a possibility of
tot(n)
tot(p) at moderately high energies. 相似文献
17.
We parametrise the polarised gluon and sea distribution functions incorporating the interpretation of the EMC experiment that, due to the axial anomaly the observed quark contribution to proton spin
at Q
2>=10.7 GeV2. Typical processes to isolate the gluonic and sea content of the proton studied here are the largeP
T
direct photon production processes (a) using single polarized protonPPX and (b) polarized beam and target protonPPX. In both the above process the dominant contribution comes from the Compton subprocess and so can be used as a clean probe of the gluonic content of the proton. LargeP
T
muon pair production PP(+–)X are also studied and we find that the annihilation subprocess dominates, but not much larger than the Compton subprocess and so may not be a clean probe of the sea content of the proton. The effect of two loop corrections to the parametrisation and asymmetries are also considered, and are found to be negligible. 相似文献
18.
We consider contributions to
c
+
, and
from excited states. The calculations are performed within the MIT-bag model and a heavy quark bag model. Because the mass of
c
+
is rather big compared to the strange baryons, excited baryon states with mass close to that of
c
+
in some cases give significant pole contributions to the decay amplitudes of
c
+
. 相似文献
19.
Structural phase transformations of the hcp bcc fct fcc fct ( ) type in titanium hydrides TiH
x
experimentally found to occur with increase in the hydrogen concentration x are studied theoretically. Free energy phases are statistically calculated, and their concentration dependence is determined. Phase transformation temperatures are found from intersection points of free energy curves and from points of common tangents to the curves. The energy parameters of the system are estimated. The calculation results are compared with the experimental data. 相似文献
20.
The couplings of conventional and hybrid mesons to (real and virtual) and their production amplitudes in M are described in a unified manner. Existing results for heavy quarks are recovered, extensions to light quarks and to virtual couplings are made and phenomenological applications discussed. In particular we discuss relativistic corrections to 0+, 1+, 2+ for both real and virtual photons and offer a resolution to a long standing puzzle in perturbative QCD concerning the helicity structure of 2++. We suggest that the production off
2 (1720) involves gluons in an essential way or that this meson hasJ2. 相似文献