共查询到20条相似文献,搜索用时 641 毫秒
1.
K. Ikematsu K. Fujii Z. Hioki Y. Sumino T. Takahashi 《The European Physical Journal C - Particles and Fields》2003,29(1):1-10
We developed a new method for the full kinematical reconstruction of the system near its threshold at future linear e
+
e
-
colliders. In the core of the method lies likelihood fitting which is designed to improve measurement accuracies of the kinematical
variables that specify the final states resulting from decays. The improvement is demonstrated by applying this method to a Monte Carlo sample generated with various experimental effects including beamstrahlung, finite acceptance and resolution of the detector
system, etc. In most cases the fit takes a broad non-Gaussian distribution of a given kinematical variable to a nearly Gaussian
shape, thereby justifying phenomenological analyses based on simple Gaussian smearing of the parton-level momenta. The standard
deviations of the resultant distributions of various kinematical variables are given in order to facilitate such phenomenological
analyses. A possible application of the kinematical fitting method and its expected impact are also discussed.
Received: 4 March 2003 / Published online: 23 May 2003
RID="a"
ID="a" e-mail: ikematsu@post.kek.jp
RID="b"
ID="b" e-mail: fujiik@jlcuxf.kek.jp
RID="c"
ID="c" e-mail: hioki@ias.tokushima-u.ac.jp
RID="d"
ID="d" e-mail: sumino@tuhep.phys.tohoku.ac.jp
RID="e"
ID="e" e-mail: tohrut@hiroshima-u.ac.jp 相似文献
2.
3.
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
4.
J. Bordes Chan Hong-Mo Tsou Sheung Tsun 《The European Physical Journal C - Particles and Fields》2003,27(2):189-200
It is shown that existing data on the mixing between up and down fermion states and on the hierarchical mass ratios between
fermion generations, as far as can be so analyzed at present, are all consistent with the two phenomena being both consequences
of a mass matrix rotating in generation space with changing energy scale. As a result, the rotating mass matrix can be traced
over some 14 orders of magnitude in energy from the mass scale of the t quark at 175 GeV to below that of the atmospheric neutrino at 0.05 eV.
Received: 27 August 2002 / Published online: 24 January 2003
RID="a"
ID="a" e-mail: jose.m.bordes@uv.es
RID="b"
ID="b" e-mail: h.m.chan@rl.ac.uk
RID="c"
ID="c" e-mail: tsou@maths.ox.ac.uk 相似文献
5.
B. Badełek J. Kwiecinski B. Ziaja 《The European Physical Journal C - Particles and Fields》2002,26(1):45-49
Theoretical predictions for the polarized nucleon structure function g
1
(x, Q
2
) at low Q2 are obtained in the framework of the generalized vector meson dominance model. Contributions from both light and heavy vector
mesons are evaluated. In the photoproduction limit the first moment of g1 is related to the static properties of the nucleon via the Drell-Hearn-Gerasimov-Hosoda-Yamamoto sum rule. This property
is employed to fix the magnitude of the light vector meson contribution to g1, using the recent measurements in the region of baryonic resonances. The results are compared to the data on g
1
(x, Q
2
). Finally, the DHGHY moment function I(Q
2
) is calculated, and our theoretical predictions are confronted with the recent preliminary data obtained at the Jefferson
Laboratory.
Received: 9 July 2002 / Published online: 7 October 2002
RID="a"
ID="a" e-mail: badelek@fuw.edu.pl
RID="b"
ID="b" e-mail: jan.kwiecinski@ifj.edu.pl
RID="c"
ID="c" e-mail: ziaja@tsl.uu.se 相似文献
6.
S. Descotes-Genon L. Girlanda J. Stern 《The European Physical Journal C - Particles and Fields》2003,27(1):115-134
Multi-flavour chiral perturbation theory (PT) may exhibit instabilities due to vacuum fluctuations of sea pairs. Keeping the fluctuations small would require a very precise fine tuning of the low-energy constants and to , . A small deviation from these critical values - like the one suggested by the phenomenology of OZI-rule violation in the
scalar channel - is amplified by huge numerical factors inducing large effects of vacuum fluctuations. This would lead in
particular to a strong Nf dependence of chiral symmetry breaking (SB) and a suppression of the multi-flavour chiral order parameters. A simple resummation is shown to cure the instability
of PT, but it modifies the standard expressions of some O(p
2
) and O(p
4
) low-energy parameters in terms of observables. On the other hand, for r= m
s
/m > 15, the two-flavour condensate is not suppressed, due to the contribution induced by massive vacuum pairs. Thanks to the latter, the standard two-flavour PT is protected from multi-flavour instabilities and could provide a well-defined expansion scheme in powers of non-strange
quark masses.
Received: 31 July 2002 / Revised version: 6 November 2002 / Published online: 15 January 2003
RID="a"
ID="a" e-mail: sdg@hep.phys.soton.ac.uk
RID="b"
ID="b" e-mail: luca.girlanda@pd.infn.it * Present address: ECT*, Villa Tambosi, Strada delle Tabarelle 286, 38050 Trento, Italy
RID="c"
ID="c" e-mail: stern@ipno.in2p3.fr 相似文献
7.
D. Bucurescu A. Gadea Ghe. Căta-Danil I. Căta-Danil M. Ivaşcu N. Mărginean C. Rusu L. Stroe C.A. Ur 《The European Physical Journal A - Hadrons and Nuclei》2003,16(4):469-474
High-spin states in the 97Tc nucleus have been studied by in-beam γ-ray spectroscopy with the reaction 82Se(19F,4nγ) at 68 MeV incident energy. Excited states have been observed up to about 8 MeV excitation and spin 43/2. The observed
level scheme is compared with results of shell model calculations.
Received: 22 November 2002 / Accepted: 23 December 2002 / Published online: 18 March 2003
RID="a"
ID="a"e-mail: bucurescu@tandem.nipne.ro
RID="b"
ID="b"Present address: INFN, Laboratori Nazionali di Legnaro, Legnaro, Italy.
RID="b"
ID="b"Present address: INFN, Laboratori Nazionali di Legnaro, Legnaro, Italy.
RID="b"
ID="b"Present address: INFN, Laboratori Nazionali di Legnaro, Legnaro, Italy.
RID="c"
ID="c"Present address: Università di Padova, Padova, Italy.
Communicated by C. Signorini 相似文献
8.
F. Deppisch H. Päs A. Redelbach R. Rückl Y. Shimizu 《The European Physical Journal C - Particles and Fields》2003,28(3):365-374
We discuss the perspectives of testing the right-handed Majorana mass scale MR of the SUSY see-saw model in the mSUGRA framework. Lepton-flavor violating low energy processes are analyzed in recently
proposed post-LEP benchmark scenarios, taking into account present uncertainties and future developments in the neutrino sector.
Non-observation of in the next-generation PSI experiment will provide upper bounds on MR of the order of GeV, while on the other hand, a positive signal for at SUPERKEKB or the LHC may determine MR for a given mSUGRA scenario with an accuracy of a factor of 2.
Received: 14 June 2002 / Revised version: 7 January 2003 / Published online: 14 April 2003
RID="a"
ID="a" e-mail: deppisch@physik.uni-wuerzburg.de
RID="b"
ID="b" e-mail: paes@physik.uni-wuerzburg.de
RID="c"
ID="c" e-mail: asredelb@physik.uni-wuerzburg.de
RID="d"
ID="d" e-mail: rueckl@physik.uni-wuerzburg.de
RID="e"
ID="e" e-mail: shimizu@eken.phys.nagoya-u.ac.jp 相似文献
9.
We investigate a flexible method by which we can test the unitarity of the quark flavor-mixing matrix step by step. Singular-value-decomposition
(SVD) techniques are used in analyzing the mixing matrix over a broader parameter region than the unitarity region. Unitary
constraints let us extract CP-violating properties without any specific parameterization when the magnitudes of at least three mixing-matrix elements in
three-generation quark mixing are given. This method can al
so be applied to the analysis of lepton flavor mixing, in which only a few moduli are presently measured.
Received: 27 November 2002 / Published online: 7 March 2003
RID="a"
ID="a" e-mail: cskim@yonsei.ac.kr
RID="b"
ID="b" e-mail: jdkim@cskim.yonsei.ac.kr 相似文献
10.
Recent experiments on unzipping of RNA helix-loop structures by force have shown that ≈40-base molecules can undergo kinetic
transitions between two well-defined “open” and “closed” states, on a timescale ≈1 sec [Liphardt et al., Science 297, 733-737 (2001)]. Using a simple dynamical model, we show that these phenomena result from the slow kinetics
of crossing large free energy barriers which separate the open and closed conformations. The dependence of barriers on sequence
along the helix, and on the size of the loop(s) is analyzed. Some DNA and RNA sequences that could show dynamics on different
time scales, or three(or more)-state unzipping, are proposed. Our dynamical model is also applied to the unzipping of long
(kilo-basepair) DNA molecules at constant force.
Received 29 July 2002 / Received in final form 5 February 2003 Published online: 16 April 2003
RID="a"
ID="a"e-mail: cocco@ldfc.u-strasbg.fr
RID="b"
ID="b"e-mail: jmarko@uic.edu
RID="c"
ID="c"e-mail: monasson@lpt.ens.fr 相似文献
11.
M. Davier S. Eidelman A. Höcker Z. Zhang 《The European Physical Journal C - Particles and Fields》2003,27(4):497-521
Vacuum polarization integrals involve the vector spectral functions which can be experimentally determined from two sources:
(i) e
+
e
-
annihilation cross sections and (ii) hadronic decays. Recently results with comparable precision have become available from CMD-2 on one side, and ALEPH, CLEO and OPAL
on the other. The comparison of the respective spectral functions involves a correction from isospin-breaking effects, which
is evaluated. After the correction it is found that the dominant spectral functions do not agree within experimental and theoretical uncertainties. Some disagreement is also found for the
spectral functions. The consequences of these discrepancies for vacuum polarization calculations are presented, with the
emphasis on the muon anomalous magnetic moment. The work includes a complete re-evaluation of all exclusive cross sections,
taking into account the most recent data that became available in particular from the Novosibirsk experiments and applying
corrections for the missing radiative corrections. The values found for the lowest-order hadronic vacuum polarization contributions
are where the errors have been separated according to their sources: experimental, missing radiative corrections in e
+
e
-
data, and isospin breaking. The Standard Model predictions for the muon magnetic anomaly read where the errors account for the hadronic, light-by-light scattering and electroweak contributions. We observe deviations
with the recent BNL measurement at the 3.0 (e
+
e
-
) and 0.9 () level, when adding experimental and theoretical errors in quadrature.
Received: 27 August 2002 / Revised version: 10 January 2003 / Published online: 26 February 2003
RID="a"
ID="a" e-mail: davier@lal.in2p3.fr
RID="b"
ID="b" e-mail: simon.eidelman@cern.ch
RID="c"
ID="c" e-mail: hoecker@lal.in2p3.fr
RID="d"
ID="d" e-mail: zhangzq@lal.in2p3.fr 相似文献
12.
In treating the relativistic 3-quark problem, a dressed-quark propagator parameterization is used which is compatible with
recent lattice data and pion observables. Furthermore 2-quark correlations are modeled as a series of quark loops in the scalar
and axialvector channel. The resulting reduced Faddeev equations are solved for nucleon and delta. Nucleon electromagnetic
form factors are calculated in a fully covariant and gauge-invariant scheme. Whereas the proton electric form factor G
E and the nucleon magnetic moments are described correctly, the neutron electric form factor and the ratio G
E/G
M for the proton appear to be quenched. The influence of vector mesons on the form factors is investigated which amounts to
a 25% modification of the electromagnetic proton radii within this framework.
Received: 16 April 2002 / Accepted: 29 August 2002 / Published online: 17 January 2003
RID="a"
ID="a"Supported by a Feodor-Lynen fellowship of the Alexander-von-Humboldt foundation and the Australian Research Council.
RID="b"
ID="b"Address after April 30: MPI für Metallforschung, Heisenbergstr. 1, 70569 Stuttgart, Germany.
RID="c"
ID="c"e-mail: Reinhard.Alkofer@uni-tuebingen.de
Communicated by A. Sch?fer 相似文献
13.
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
14.
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
15.
We study the differential branching ratio, the branching ratio and the forward-backward asymmetry for exclusive decay in the two Higgs doublet model. We analyze the dependences of these quantities on the model parameters and show that
these observables are highly sensitive to new physics and hence may provide a powerful probe of the SM and beyond.
Received: 27 March 2002 / Revised version: 3 July 2002 / Published online: 20 September 2002
RID="a"
ID="a" e-mail: gurerk@newton.physics.metu.edu.tr
RID="b"
ID="b" e-mail: gsevgur@metu.edu.tr 相似文献
16.
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
17.
We study the implications of the recently improved upper limits on the branching ratios for the decays , expressed as . We work out the constraints that the current bound on implies on the parameters of the quark mixing matrix in the standard model (SM). Using the present profile of the unitarity
triangle, we predict this ratio to lie in the range (at 95% C.L.), with the central value . We also work out the correlations involving , the isospin-violating ratio , and the direct CP-violating asymmetry in decays in the SM, in the minimal supersymmetric extension of the SM (MSSM), and in an extension of the MSSM involving an
additional flavor-changing structure in transitions.
Received: 19 August 2002 / Published online: 18 October 2002
RID="a"
ID="a" e-mail: ali@mail.desy.de
RID="b"
ID="b" e-mail: lunghi@mail.desy.de 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.
G. Degrassi S. Heinemeyer W. Hollik P. Slavich G. Weiglein 《The European Physical Journal C - Particles and Fields》2003,28(1):133-143
The status of the evaluation of the MSSM Higgs sector is reviewed. The phenomenological impact of recently obtained corrections
is discussed. In particular it is shown that the upper bound on mh within the MSSM is shifted upwards. Consequently, lower limits on obtained by confronting the upper bound as function of with the lower bound on mh from Higgs searches are significantly weakened. Furthermore, th
e region in the MA--plane where the coupling of the lightest Higgs boson to down-type fermions is suppressed is modified. The presently not calculated
higher-order corrections to the Higgs-boson mass matrix are estimated to shift the mass of the lightest Higgs boson by up
to 3 GeV.
Received: 12 December 2002 / Published online: 3 March 2003
RID="a"
ID="a" e-mail: giuseppe.degrassi@roma3.infn.it
RID="b"
ID="b" e-mail: Sven.Heinemeyer@physik.uni-muenchen.de
RID="c"
ID="c" e-mail: hollik@mppmu.mpg.de
RID="d"
ID="d" e-mail: slavich@mppmu.mpg.de
RID="e"
ID="e" e-mail: Georg.Weiglein@durham.ac.uk 相似文献
20.
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