97 research outputs found
exotic meson at light quark masses
The mass of the exotic meson, created with hybrid interpolating
fields, is explored at light quark masses approaching 25 MeV (). Access to such light quark masses is facilitated by the use of
the Fat-Link Irrelevant Clover (FLIC) fermion action. Additionally, we make use
of large () lattices to obtain good control of statistical and
finite volume errors. Our results indicate that the exotic exhibits
significant curvature close the chiral limit, indicating previous linear
extrapolations, far from the chiral regime, have overestimated the mass of the
. We find for the first time in lattice studies a mass in
agreement with the candidate. We also find a strangeness 1
state with a mass close to 2 GeV.Comment: 8 pages, 11 figures, 3 tables, published versio
Experimental Status of Exotic Mesons and the GlueX Experiment
One of the unanswered and most fundamental questions in physics regards the
nature of the confinement mechanism of quarks and gluons in QCD. Exotic hybrid
mesons manifest gluonic degrees of freedom and their spectroscopy will provide
the data necessary to test assumptions in lattice QCD and the specific
phenomenology leading to confinement. Within the past two decades a number of
experiments have put forth tantalizing evidence for the existence of exotic
hybrid mesons in the mass range below 2 GeV. This talk represents an overview
of the available data and what has been learned. In looking toward the future,
the GlueX experiment at Jefferson Laboratory represents a new initiative that
will perform detailed spectroscopy of the light-quark meson spectrum. This
experiment and its capabilities will be reviewed.Comment: 10 pages, 8 figures, 2nd Meeting of the APS Topical Group on Hadron
Physics GHP06, Nashville, TN (10/22-10/24/06
Results of a beam test of the combined lead glass and PWO CELLS detector for the COMPASS electromagnetic calorimeter
Radiative Decays of the Upsilon(1S) to a Pair of Charged Hadrons
Using data obtained with the CLEO~III detector, running at the Cornell
Electron Storage Ring (CESR), we report on a new study of exclusive radiative
Upsilon(1S) decays into the final states gamma pi^+ pi^-, gamma K^+ K^-, and
gamma p pbar.. We present branching ratio measurements for the decay modes
Upsilon(1S) to gamma f_2(1270), Upsilon(1S) to gamma f_2'(1525), and
Upsilon(1S) to gamma K^+K^-; helicity production ratios for f_2(1270) and
f_2'(1525); upper limits for the decay Upsilon(1S) to gamma f_J(2200), with
f_J(2220) to pi^+ pi^-, K^+ K^-, p pbar; and an upper limit for the decay
Upsilon(1S) to gamma X(1860), with X(1860) to gamma p pbar.Comment: 17 pages postscript,also available through
http://www.lns.cornell.edu/public/CLNS/2005/, Submitted to PR
Evidence for Exotic J^{PC}=1^{-+} Meson Production in the Reaction pi- p --> eta pi- p at 18 GeV/c
Details of the analysis of the eta pi- system studied in the reaction pi^{-}
p --> eta pi^{-} p at 18 GeV/c are given. Separate analyses for the 2 gamma and
pi+ pi- pi0 decay modes of the eta are presented. An amplitude analysis of the
data indicates the presence of interference between the a(2)(1320)- and a
J^{PC}=1^{-+} wave between 1.2 and 1.6 GeV/c^2. The phase difference between
these waves shows phase motion not attributable solely to the a(2)(1320)-. The
data can be fitted by interference between the a(2)(1320)- and an exotic 1^{-+}
resonance with M = 1370 +-16 +50 -30} MeV/c^2 and Gamma = 385 +- 40 +65 -105
MeV/c^2. Our results are compared with those of other experiments.Comment: 50 pages of text and 34 figure
Simulation of the thermally induced austenitic phase transition in NiTi nanoparticles
The reverse martensitic ("austenitic") transformation upon heating of
equiatomic nickel-titanium nanoparticles with diameters between 4 and 17 nm is
analyzed by means of molecular-dynamics simulations with a semi-empirical model
potential. After constructing an appropriate order parameter to distinguish
locally between the monoclinic B19' at low and the cubic B2 structure at high
temperatures, the process of the phase transition is visualized. This shows a
heterogeneous nucleation of austenite at the surface of the particles, which
propagates to the interior by plane sliding, explaining a difference in
austenite start and end temperatures. Their absolute values and dependence on
particle diameter are obtained and related to calculations of the surface
induced size dependence of the difference in free energy between austenite and
martensite.Comment: 6 pages, 4 figures, accepted for publication in "The European
Physical Journal B
国际化十年:一家澳大利亚零售银行的经验之谈
上个世纪最后四十年见证了国际银行业务和跨国银行业务显著增长的历程。推动这一发展的力量包括全球化、解除管制以及信息技术的发展。在19世纪及20世纪初发生的第一次现代意义上的跨国银行业务发展浪潮中,那些来自殖民宗主国的银行领导了时代潮流。而在最近的这次跨国银行业务扩张中,美国的金融机构占据了领导地位,这是与第一次明显不同的。因此,许多学术文章都着重研究美国的银行,包括他们的动机、经营战略以及国际化经验。此外,与银行业国际化的第一阶段相比,此次银行业的国际化扩张更大程度地突出了批发和机构银行业务,而不是零售银行业务(除了少数例外)。这一特点在近年来对跨国银行经营的学术研究中也体现得十分明显[ 有关调查,见Bain,et al (2001)。]。译者单位:厦门大学经济学院国际经济与贸易系(361005
Non-factorizable contributions in hadronic weak decays of charm mesons
Two body decays of charm mesons are studied by describing their amplitude in
terms of a sum of factorizable and non-factorizable ones. The former is
estimated by using a naive factorization while the latter is calculated by
using a hard pseudo-scalar-meson approximation. The hard pseudo-scalar-meson
amplitude is given by a sum of the so-called equal-time commutator term and
surface term which contains all possible pole contributions of various mesons,
not only the ordinary but also four-quark ,
hybrid and glue-balls.
Naively factorized amplitudes for the spectator decays which lead to too big
rates can interfere destructively with exotic meson pole amplitudes and the
total amplitudes can reproduce their observed rates. The non-factorizable
contributions can supply sufficiently large contributions to the color
suppressed decays which are strongly suppressed in the naive factorization. A
possible solution to the long standing puzzle that the ratio of decay rates for
to is around 2.5 is given by different
contributions of exotic meson poles.Comment: 22 pages, RevTe
A kinematical selection of glueball candidates in central production
A study of central meson production as a function of the difference in transverse momentum () of the exchanged particles shows that undisputed mesons are suppressed at small whereas the glueball candidates are enhanced
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