共查询到20条相似文献,搜索用时 46 毫秒
1.
2.
T.M. Aliev A. Özpineci M. Savci 《The European Physical Journal C - Particles and Fields》2003,29(2):265-270
We study the effects of sequential fourth quark generation in rare decays induced by the transition and in B
s
0- mixing. Using the experimental values on the branching ratios of the and decays, the allowed regions for and are determined as a function of the t
'
quark mass.
Received: 3 April 2003 / Published online: 2 June 2003
RID="a"
ID="a" e-mail: taliev@metu.edu.tr
RID="b"
ID="b" e-mail: ozpineci@ictp.trieste.it
RID="c"
ID="c" e-mail: savci@metu.edu.tr 相似文献
3.
We extract the neutron charge form factor G
n
E(Q
2) from the charge form factor of deuteron G
d
C(Q
2) obtained from T
20(Q
2) data at 0≤Q
2≤ 1.717 (GeV/c)2. The extraction is based on the relativistic impulse approximation in the instant form of the relativistic Hamiltonian dynamics.
Our results (12 new points) are compatible with existing values of the neutron charge form factor of other authors. We propose
a fit for the whole set (36 points) taking into account the data for the slope of the form factor at Q
2 = 0.
Received: 26 July 2002 / Accepted: 18 September 2002 / Published online: 4 February 2003
RID="a"
ID="a"e-mail: krutov@ssu.samara.ru
RID="b"
ID="b"e-mail: troitsky@theory.sinp.msu.ru
Communicated by V.V. Anisovich 相似文献
4.
M.P. Rekalo E. Tomasi-Gustafsson 《The European Physical Journal A - Hadrons and Nuclei》2003,16(4):563-567
We discuss the applicability of pQCD to the elastic scattering of electrons on protons and deuterons. We analyze the Q2-dependence of the reduced deuteron form factor, taking into account the recent data on the electric proton form factor and
we find that the value of the QCD-scale parameter Λ differs essentially from the value Λ = 0.1 GeV, previously found using
the dipole parametrization of the electromagnetic nucleon form factors GE and GM. Moreover, the predicted scaling behavior of the reduced deuteron form factor cannot be recovered in the Dirac and Pauli
representations for the nucleon electromagnetic form factors.
Received: 14 October 2002 / Accepted: 12 November 2002 / Published online: 11 March 2003
RID="a"
ID="a"Permanent address: National Science Center KFTI, 310108 Kharkov, Ukraine.
RID="b"
ID="b"e-mail: etomasi@cea.fr
Communicated by V.V. Anisovich 相似文献
5.
Charmonium sum rules are analyzed with the primary goal to obtain the restrictions on the value of the dimension 4 gluon
condensate. The moments M
n
(Q
2
) of the polarization operator of the vector charm currents are calculated and compared with the experimental data. The three-loop
() perturbative corrections, the contribution of the gluon condensate with corrections and the contribution of the dimension 6 operator G3 are accounted. It is shown that the sum rules for the moments do not work at Q
2
= 0, where the perturbation series diverges and the G3 contribution is large. The domain in the (n, Q
2
) plane where the sum rules are legitimate is found. A strong correlation of the values of gluon condensate and charm quark mass is determined. The absolute limits are found to be for the gluon condensate and for the charm quark mass in the scheme.
Received: 16 July 2002 / Revised version: 6 November 2002 / Published online: 24 January 2003
RID="a"
ID="a" e-mail: ioffe@vitep1.itep.ru
RID="b"
ID="b" e-mail: zyablyuk@heron.itep.ru 相似文献
6.
We deconstruct the non-supersymmetric SU(5) breaking by discrete symmetry on the space-time and in the Higgs mechanism deconstruction scenario. Also we explain the subtle point of how to exactly match the continuum results
with the latticized results on the quotient space S
1
/Z
2
and . We also propose an effective deconstruction scenario and discuss the gauge symmetry breaking by the discrete symmetry on
the theory space in this approach. As an application, we suggest the GN unification where GN is broken down to by the bifundamental link fields and the doublet-triplet splitting can be achieved.
Received: 10 October 2002 / Revised version: 23 March 2003 / Published online: 13 May 2003
RID="a"
ID="a" Current address: School of Natural Sciences, Institute for Advanced Study, Einstein Drive, Princeton, NJ 08540, USA
e-mail: tli@sns.ias.edu
RID="b"
ID="b" e-mail: liutao@sas.upenn.edu 相似文献
7.
We calculate the , (P is the light pseudoscalar meson, V the light vector meson) form factors in the large-recoil limit in the perturbative QCD approach, including both the vector
(axial vector) and tensor operators. In general there are two leading components and for the B meson wave functions. We consider both contributions of them. Sudakov effects ( and threshold resummation) are included to regulate the soft end-point singularity. By choosing the hard scale as the maximum
virtualities of the internal particles in the hard b quark decay amplitudes, Sudakov factors can effectively suppress the long-distance soft contribution. The hard contribution
can be dominant in these approaches.
Received: 27 December 2002 / Published online: 5 May 2003
RID="a"
ID="a" e-mail: lucd@mail.ihep.ac.cn
RID="b"
ID="b" e-mail: yangmz@mail.ihep.ac.cn 相似文献
8.
M. Slusarczyk A. Wereszczynski 《The European Physical Journal C - Particles and Fields》2003,28(1):151-154
The generalization of QCD motivated classical SU(2) Yang-Mills theory coupled to a scalar field is discussed. The massive scalar field, corresponding to the scalar glueball,
provides a confining potential for static, point-like, external sources. In the case of a massless scalar field screening
solutions are found. However, there is a confining sector as well. Both, massive and massless confining solutions, are compared
with phenomenological potentials. The case of a non-dynam
ical permittivity is also discussed.
Received: 15 November 2002 / Revised version: 31 January 2003 / Published online: 7 March 2003
RID="a"
ID="a" e-mail: mslus@phys.ualberta.ca
RID="b"
ID="b" e-mail: wereszcz@alphas.if.uj.edu.pl 相似文献
9.
W. Urban J.A. Pinston T. Rzaca-Urban A. Złomaniec G. Simpson J.L. Durell W.R. Phillips A.G. Smith B.J. Varley I. Ahmad N. Schulz 《The European Physical Journal A - Hadrons and Nuclei》2003,16(1):11-15
A new band, populated by the spontaneous fission of 248Cm and studied by means of prompt γ-ray spectroscopy using the EUROGAM2 array, was observed in 99Zr. The 1038.8 keV band head with a half-life T
1/2 = 54(10) ns is interpreted as a K-isomer, corresponding to the 9/2[404] neutron-hole excitation. It is the first observation of this orbital in the mass A ∼ 100 region. The quadrupole moment, Q
0 = 3.9(3) eb deduced for the new band indicates a large deformation of β = 0.41, which is produced by a specific shape-coexistence
mechanism, known in other regions and now found in the A ∼ 100 nuclei.
Received: 11 September 2002 / Accepted: 31 October 2002 / Published online: 17 January 2003
RID="a"
ID="a"e-mail: urban@fuw.edu.pl
Communicated by D. Schwalm 相似文献
10.
S.U. Chung E. Klempt J.G. Körner 《The European Physical Journal A - Hadrons and Nuclei》2002,15(4):539-542
An exotic meson, the π1(1400) with J
PC = 1- +, has been seen to decay into a p-wave ηπ system. If this decay conserves flavor SU(3), then it can be shown that this exotic meson must be a four-quark state ( qˉq + qˉq) belonging to a flavor ˉ10 representation of SU(3). In contrast, the π1(1600) with a substantial decay mode into π is likely to be a member of a flavor octet.
Received: 27 March 2002 / Accepted: 8 August 2002 / Published online: 10 December 2002
RID="b"
ID="b"e-mail: klempt@iskp.uni-bonn.de
Communicated by V. Vento 相似文献
11.
V.K. Henner P.G. Frick T.S. Belozerova V.G. Solovyev 《The European Physical Journal C - Particles and Fields》2002,26(1):3-7
We demonstrate the advantages of the wavelet analysis (WA) for resolving the structures in experimental data on e
+
e
-
annihilation into hadron states with quantum numbers of meson. The WA yields a useful set of starting conditions for analysis of states with multiresonance unitary Breit-Wigner method. We also apply the WA for the ratio R
e+e-
.
Received: 4 February 2002 / Revised version: 28 August 2002 / Published online: 18 October 2002
RID="a"
ID="a" e-mail: vhenner@python.physics.louisville.edu and henner@psu.ru 相似文献
12.
We consider the spin-glass phase of the Sherrington-Kirkpatrick model in the presence of a magnetic field. The series expansion
of the Parisi function q(x) is computed at high orders in powers of τ = T
c - T and H. We find that none of the Parisi-Toulouse scaling hypotheses on the q(x) behavior strictly holds, although some of them are violated only at high orders. The series is resummed yielding results
in the whole spin-glass phase which are compared with those from a numerical evaluation of the q(x). At the high order considered, the transition turns out to be third order on the Almeida-Thouless line, a result which is
confirmed rigorously computing the expansion of the solution near the line at finite τ. The transition becomes smoother for
infinitesimally small field while it is third order at strictly zero field.
Received 3 March 2003 Published online 4 June 2003
RID="a"
ID="a"e-mail: andrea.crisanti@phys.uniroma1.it
RID="b"
ID="b"e-mail: tommaso.rizzo@phys.uniroma1.it
RID="c"
ID="c"e-mail: temtam@helios.elte.hu 相似文献
13.
Bo-Wen Xiao Xin Qian Bo-Qiang Ma 《The European Physical Journal A - Hadrons and Nuclei》2002,15(4):523-527
The electromagnetic form factor of the kaon meson is calculated in the light-cone formalism of the relativistic constituent
quark model. The calculated K+ form factor is consistent with almost all of the available experimental data at low-energy scale, while other properties
of the kaon could also be interrelated in this representation with reasonable parameters. Predictions of the form factors
for the charged and neutral kaons at a higher-energy scale are also given, and we find the non-zero K0 form factor at Q
2≠ 0 due to the mass difference between the strange and down quarks inside K0.
Received: 21 June 2002 / Accepted: 29 July 2002 / Published online: 3 December 2002
RID="a"
ID="a"e-mail: mabq@phy.pku.edu.cn
Communicated by A. Sch?fer 相似文献
14.
B.A. Hamad T. Khajil J.M. Khalifeh 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(3):497-501
The magnetism is calculated for substitutional alloyed of Crx(Mnx)V1-x monolayers (MLs) and CrxMn1-x on V (001) surface with a variety of concentrations (x
= 0.25, 0.50 and 0.75). The substitutional surface alloys were treated by an artificial super cell construction. Parallel magnetic
ordering is obtained for all the considered structures. The surface net magnetization increases in terms of Cr (Mn) concentration
in Crx(Mnx)V1-x/V (001) system, while no serious variations occur in CrxMn1-x/V (001). Vanadium atoms at the interfacial layers acquire appreciable magnetic moments antiferromagneticlly (AF) coupled
with the surface moments.
Received 25 February 2002 / Received in final form 13 May 2002 Published online 14 October 2002
RID="a"
ID="a"e-mail: jkalifa@sci.ju.edu.jo 相似文献
15.
T. Dobrowolski 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):269-271
The production of topological defects during a quench in a φ4 model is investigated. The influence of a spatially correlated noise on defect production in two and three dimensions is
demonstrated.
Received 28 August 2001 / Received in final form 11 February 2002 Published online 2 October 2002
RID="a"
ID="a"Paper supported in part by ESF “COSLAB” Programme
RID="b"
ID="b"e-mail: sfdobrow@kinga.cyf-kr.edu.pl 相似文献
16.
M. Lach J. Styczeń W. Meczyński P. Bednarczyk A. Bracco J. Grebosz A. Maj J.C. Merdinger N. Schulz M.B. Smith K.M. Spohr J.P. Vivien M. Ziebliński 《The European Physical Journal A - Hadrons and Nuclei》2003,16(3):309-311
High-spin states of the 42Ca nucleus, populated in the 68 MeV 18O + 30Si reaction, have been studied in a γ-γ-recoil coincidence experiment. The level scheme of 42Ca has been extended up to 13.7 MeV. An elaborate decay pattern with various paths, together with high-quality DCO and polarization
information assigns spins and parities for almost all observed levels. The sequence of non-yrast positive-parity states is
discussed and compared with highly deformed bands in 36Ar and 40Ca.
Received: 26 November 2002 / Accepted: 11 December 2002 / Published online: 18 February 2003
RID="a"
ID="a"e-mail: Malgorzata.Lach@ifj.edu.pl
RID="b"
ID="b"Present address: TRIUMF, Vancouver, Canada.
RID="†"
ID="†"Deceased.
Communicated by D. Schwalm 相似文献
17.
E. Martynov E. Predazzi A. Prokudin 《The European Physical Journal C - Particles and Fields》2002,26(2):271-284
A model based on a dipole pomeron framework for exclusive vector meson photoproduction by real and virtual photons shows
very good agreement with the experimental data. This model does not violate unitarity constraints and describes in a universal
manner all the available data for , , , and vector meson photoproduction in the region of energies and photon virtualities .
Received: 18 December 2001 / Published online: 25 October 2002
RID="a"
ID="a" e-mail: martynov@bitp.kiev.ua
RID="b"
ID="b" e-mail: predazzi@to.infn.it
RID="c"
ID="c" e-mail: prokudin@to.infn.it 相似文献
18.
H. Czyz A. Grzelinska J.H. Kühn G. Rodrigo 《The European Physical Journal C - Particles and Fields》2003,27(4):563-575
The radiative return offers the unique possibility for a measurement of the cross section of electron-positron annihilation
into hadrons over a wide range of energies. The large luminosity of present - and B-factories easily compensates for the additional factor of due to the emission of a hard photon. Final states with photons at large angles can be easily identified. The rate for events
with collinear photons, however, is enhanced by a large logarithm and allows, in particular at lower energies, for a complementary
measurement. The Monte Carlo generator PHOKHARA, which includes next-to-leading order corrections from virtual and real photon
emission, has been extended from large photon angles into the collinear region, using recent results for the virtual corrections.
In addition, the present version includes final state radiation for muon and pion pair production and final states with four
pions. Implications for the experimental analysis at three typical energies, 1.02, 4 and 10.6 GeV, are presented: the magnitude
of these new corrections is studied, possibilities for the separation of initial and final state radiation are proposed, and
the differences with respect to the previous treatment based on structure functions are investigated.
Received: 16 December 2002 / Published online: 26 February 2003
RID="a"
ID="a" e-mail: czyz@us.edu.pl
RID="b"
ID="b" e-mail: grzel@joy.phys.us.edu.pl, Supported in part by "Marie Curie Training Site" at Karlsruhe University
RID="c"
ID="c" e-mail: jk@particle.uni-karlsruhe.de
RID="d"
ID="d" e-mail: german.rodrigo@cern.ch, Supported in part by E.U. TMR grant HPMF-CT-2000-00989 相似文献
19.
V. Bernard T. R. Hemmert U.-G. Meißner 《The European Physical Journal A - Hadrons and Nuclei》2003,18(2-3):503-505
We present novel results for the first moment of the spin-dependent structure function g
1(x,Q
2) of the nucleon at small (Q
2 < 0.3 GeV2) photon virtuality in the framework of a relativistic formulation of baryon chiral perturbation theory. We perform a next-to-leading order calculation and obtain significant differences to previously found results based on the heavy-baryon approach for the proton and neutron.Received: 30 September 2002, Published online: 22 October 2003PACS:
12.39.Fe Chiral Lagrangians - 14.20.Dh Protons and neutrons 相似文献
20.
We show that maximal atmospheric and large solar neutrino mixing can be implemented in SU(5) gauge theories, by making use of the U(1)
F
symmetry associated with a suitably defined family number F, together with a Z2 symmetry which does not commute with F. U(1)
F
is softly broken by the mass terms of the right-handed neutrino singlets, which are responsible for the seesaw mechanism;
in additio
n, U(1)
F
is also spontaneously broken at the electroweak scale. In our scenario, lepton mixing stems exclusively from the right-handed-neutrino
Majorana mass matrix, whereas the CKM matrix originates solely in the up-type-quark sector. We show that, despite the non-supersymmetric
character of our model, unification of the gauge couplings can be achieved at a scale 1016 GeV < m
U
< 1019 GeV; indeed, we have found a particula
r solution to this problem which yields results almost identical to the ones of the minimal supersymmetric standard model.
Received: 29 November 2002 / Published online: 3 March 2003
RID="a"
ID="a" e-mail: walter.grimus@univie.ac.at
RID="b"
ID="b" e-mail: balio@cfif.ist.utl.pt 相似文献