463 research outputs found
Search for decay at Super factory
A Monte Carlo study of possible background processes in a search for decay has been performed for conditions of the Super
factory (CTF) (at a center-of-mass energy 3.686 GeV, 3.77 GeV and 4.17 GeV).
The background from events has been analysed. Selection
criteria for background suppression are suggested and necessary requirements on
the detector characteristics have been found. The CTF can successfully compete
with the Super B-factory in a search for decay.Comment: 3 pages, 1 figures; contribution to the Proceedings of the PHIPSI11
Workshop (Novosibirsk, Russia, 19-22 September 2011
Public sector reforms, privatisation and regimes of control in a Chinese enterprise
The Chinese economic reform has recently become a major focus of attention around the world. The underlying rationale for the Chinese government's privatisation and public sector reforms is the view that reformed state enterprises and privately managed firms will demonstrate superior management control and better performance, and hence encourage economic growth and employment. There are very few intensive case studies published in English journals studying whether firms privatised in China have reversed previous losses and introduced better management controls, leading to increased investment, productivity, and overall organizational effectiveness and efficiency. The researchers do not seek to deny the control problems of Chinese SOEs, but question the consequences of the new controls installed during the post-privatisation period. The paper also reveals a declining tendency in employment; altered distributions of wealth ? especially to the state ? and labour, and a lack of improvements in the accountability of privatised companies. Overall, the paper argues, the aims of reform policies in China, including better control, increased profitability and an improved working life for Chinese people, have not materialized. The paper calls for more research on the above issues in the Chinese context
An Atom Laser Based on Raman Transitions
In this paper we present an atom laser scheme using a Raman transition for
the output coupling of atoms. A beam of thermal atoms (bosons) in a metastable
atomic state are pumped into a multimode atomic cavity. This cavity is
coupled through spontaneous emission to a single mode of another cavity for the
ground atomic state, . Above a certain threshold pumping rate a large
number of atoms, , builds up in this single quantum state and transitions
to the ground state of the cavity become enhanced by a factor .
Atoms in this state are then coupled to the outside of the cavity with a Raman
transition. This changes the internal state of the atom and imparts a momentum
kick, allowing the atoms to leave the system.Comment: 8 pages, 4 postscript figures, uses RevTex, home page at
http://online.anu.edu.au/Physics/Welcome.html (Some aspects of the exact
physical model have changed from original version. Other general improvements
included
Perturbed angular correlations for Gd in gadolinium: in-beam comparisons of relative magnetizations
Perturbed angular correlations were measured for Gd ions implanted into
gadolinium foils following Coulomb excitation with 40 MeV O-16 beams. A
technique for measuring the relative magnetizations of ferromagnetic gadolinium
hosts under in-beam conditions is described and discussed. The combined
electric-quadrupole and magnetic-dipole interaction is evaluated. The effect of
nuclei implanted onto damaged or non-substitutional sites is assessed, as is
the effect of misalignment between the internal hyperfine field and the
external polarizing field. Thermal effects due to beam heating are discussed.Comment: 37 pages, 15 figures, accepted for publication in NIM
Spectral quark model and low-energy hadron phenomenology
We propose a spectral quark model which can be applied to low energy hadronic
physics. The approach is based on a generalization of the Lehmann
representation of the quark propagator. We work at the one-quark-loop level.
Electromagnetic and chiral invariance are ensured with help of the gauge
technique which provides particular solutions to the Ward-Takahashi identities.
General conditions on the quark spectral function follow from natural physical
requirements. In particular, the function is normalized, its all positive
moments must vanish, while the physical observables depend on negative moments
and the so-called log-moments. As a consequence, the model is made finite,
dispersion relations hold, chiral anomalies are preserved, and the twist
expansion is free from logarithmic scaling violations, as requested of a
low-energy model. We study a variety of processes and show that the framework
is very simple and practical. Finally, incorporating the idea of vector-meson
dominance, we present an explicit construction of the quark spectral function
which satisfies all the requirements. The corresponding momentum representation
of the resulting quark propagator exhibits only cuts on the physical axis, with
no poles present anywhere in the complex momentum space. The momentum-dependent
quark mass compares very well to recent lattice calculations. A large number of
predictions and relations can be deduced from our approach for such quantities
as the pion light-cone wave function, non-local quark condensate, pion
transition form factor, pion valence parton distribution function, etc.Comment: revtex, 24 pages, 3 figure
Large lepton asymmetry from Q-balls
We propose a scenario which can explain large lepton asymmetry and small
baryon asymmetry simultaneously. Large lepton asymmetry is generated through
Affleck-Dine (AD) mechanism and almost all the produced lepton numbers are
absorbed into Q-balls (L-balls). If the lifetime of the L-balls is longer than
the onset of electroweak phase transition but shorter than the epoch of big
bang nucleosynthesis (BBN), the large lepton asymmetry in the L-balls is
protected from sphaleron effects. On the other hand, small (negative) lepton
numbers are evaporated from the L-balls due to thermal effects, which are
converted into the observed small baryon asymmetry by virtue of sphaleron
effects. Large and positive lepton asymmetry of electron type is often
requested from BBN. In our scenario, choosing an appropriate flat direction in
the minimal supersymmetric standard model (MSSM), we can produce positive
lepton asymmetry of electron type but totally negative lepton asymmetry.Comment: 10 pages, 3 figures, ReVTeX
Low Energy Chiral Lagrangian in Curved Space-Time from the Spectral Quark Model
We analyze the recently proposed Spectral Quark Model in the light of Chiral
Perturbation Theory in curved space-time. In particular, we calculate the
chiral coefficients , as well as the coefficients ,
, and , appearing when the model is coupled to gravity. The
analysis is carried for the SU(3) case. We analyze the pattern of chiral
symmetry breaking as well as elaborate on the fulfillment of anomalies.
Matching the model results to resonance meson exchange yields the relation
between the masses of the scalar, tensor and vector mesons,
. Finally, the
large- limit suggests the dual relations in the vector and scalar
channels, and .Comment: 18 pages, no figure
Valence-quark distributions in the pion
We calculate the pion's valence-quark momentum-fraction probability
distribution using a Dyson-Schwinger equation model. Valence-quarks with an
active mass of 0.30 GeV carry 71% of the pion's momentum at a resolving scale
q_0=0.54 GeV = 1/(0.37 fm). The shape of the calculated distribution is
characteristic of a strongly bound system and, evolved from q_0 to q=2 GeV, it
yields first, second and third moments in agreement with lattice and
phenomenological estimates, and valence-quarks carrying 49% of the pion's
momentum. However, pointwise there is a discrepancy between our calculated
distribution and that hitherto inferred from parametrisations of extant
pion-nucleon Drell-Yan data.Comment: 8 pages, 3 figures, REVTEX, aps.sty, epsfig.sty, minor corrections,
version to appear in PR
Modeling accuracy as a function of response time with the generalised linear mixed effects model
In psycholinguistic studies using error rates as a response measure, response times (RT) are most often analyzed independently of the error rate, although it is widely recognized that they are related. In this paper we present a mixed effects logistic regression model for the error rate that uses RT as a trial-level fixed- and random-effect regression input. Production data from a translation–recall experiment are analyzed as an example. Several model comparisons reveal that RT improves the fit of the regression model for the error rate. Two simulation studies then show how the mixed effects regression model can identify individual participants for whom (a) faster responses are more accurate, (b) faster responses are less accurate, or (c) there is no relation between speed and accuracy. These results show that this type of model can serve as a useful adjunct to traditional techniques, allowing psycholinguistic researchers to examine more closely the relationship between RT and accuracy in individual subjects and better account for the variability which may be present, as well as a preliminary step to more advanced RT–accuracy modeling
Transversity Form Factors and Generalized Parton Distributions of the pion in chiral quark models
The transversity Generalized Parton Distributions (tGPDs) and related
transversity form factors of the pion are evaluated in chiral quark models,
both local (Nambu--Jona-Lasinio) and nonlocal, involving a momentum-dependent
quark mass. The obtained tGPDs satisfy all a priori formal requirements, such
as the proper support, normalization, and polynomiality. We evaluate
generalized transversity form factors accessible from the recent lattice QCD
calculations. These form factors, after the necessary QCD evolution, agree very
well with the lattice data, confirming the fact that the spontaneously broken
chiral symmetry governs the structure of the pion also in the case of the
transversity observables.Comment: 6 pages, 3 figures, presented by WB at LIGHTCONE 2011, 23 - 27 May,
2011, Dalla
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