62,775 research outputs found
KN and KbarN Elastic Scattering in the Quark Potential Model
The KN and KbarN low-energy elastic scattering is consistently studied in the
framework of the QCD-inspired quark potential model. The model is composed of
the t-channel one-gluon exchange potential, the s-channel one-gluon exchange
potential and the harmonic oscillator confinement potential. By means of the
resonating group method, nonlocal effective interaction potentials for the KN
and KbarN systems are derived and used to calculate the KN and KbarN elastic
scattering phase shifts. By considering the effect of QCD renormalization, the
contribution of the color octet of the clusters (qqbar) and (qqq) and the
suppression of the spin-orbital coupling, the numerical results are in fairly
good agreement with the experimental data.Comment: 20 pages, 8 figure
Closed expression of the interaction kernel in the Bethe-Salpeter equation for quark-antiquark bound states
The interaction kernel in the Bethe-Salpeter equation for quark-antiquark
bound states is derived from the Bethe-Salpeter equations satisfied by the
quark-antiquark four-point Green's function. The latter equations are
established based on the equations of motion obeyed by the quark and antiquark
propagators, the four-point Green's function and some other kinds of Green's
functions which follow directly from the QCD generating functional. The B-S
kernel derived is given an exact and explicit expression which contains only a
few types of Green's functions. This expression is not only convenient for
perturbative calculations, but also suitable for nonperturbative
investigations.Comment: 27 pages,no figure
Top-Quark Mass Measurement in the Dilepton Channel Using {\it in situ} Jet Energy Scale Calibration
We employ a top-quark mass measurement technique in the dilepton channel with
{\it in situ} jet energy scale calibration. Three variables having different
jet energy scale dependences are used simultaneously to extract not only the
top-quark mass but also the energy scale of the jet from a single likelihood
fit. Monte Carlo studies with events corresponding to an integrated luminosity
of 5 fb proton-proton collisions at the Large Hadron Collider TeV are performed. Our analysis suggests that the overall jet energy scale
uncertainty can be significantly reduced and the top-quark mass can be
determined with a precision of less than 1 GeV/c, including jet energy
scale uncertainty, at the Large Hadron Collider.Comment: Submitted to Phys. Rev.
Making it Rich and Personal: crafting an institutional personal learning environment
Many of the communities interested in learning and teaching technologies within higher education now accept the view that a conception of personal learning environments provides a the most realistic and workable perspective of learnersâ interactions with and use of technology. This view may not be reflected in the behaviour of those parts of a university which normally purchase and deploy technology infrastructure. These departments or services are slow to change because they are typically, and understandably, risk-averse; the more so, because the consequences of expensive decisions about infrastructure will stay with the organisation for many years. Furthermore across the broader (less technically or educationally informed) academic community, the awareness of and familiarity with technologies in support of learning may be varied. In this context, work to innovate the learning environment will require considerable team effort and collective commitment. This paper presents a case study account of institutional processes harnessed to establish a universal personal learning environment fit for the 21st century. The challenges encountered were consequential of our working definition of a learning environment, which went beyond simple implementation. In our experience the requirements became summarised as âits more than a system, itâs a mindsetâ. As well as deploying technology âfit for purposeâ we were seeking to create an environment that could play an integral and catalytic part in the universityâs role of enabling transformative education. Our ambitions and aspirations were derived from evidence in the literature. We also drew on evidence of recent and current performance in the university; gauged by institutional benchmarking and an extensive student survey. The paper presents and analyses this qualitative and quantitative data. We provide an account and analysis of our progress to achieve change, the methods we used, problems encountered and the decisions we made on the way
Quantum communication in the presence of a horizon
Based on homodyne detection, we discuss how the presence of an event horizon
affects quantum communication between an inertial partner, Alice, and a
uniformly accelerated partner, Rob. We show that there exists a low frequency
cutoff for Rob's homodyne detector that maximizes the signal to noise ratio and
it approximately corresponds to the Unruh frequency. In addition, the low
frequency cutoff which minimizes the conditional variance between Alice's input
state and Rob's output state is also approximately equal to the Unruh
frequency. Thus the Unruh frequency provides a natural low frequency cutoff in
order to optimize quantum communication of both classical and quantum
information between Alice and Rob.Comment: 7 pages, 6 figure
Renormalization of the Sigma-Omega model within the framework of U(1) gauge symmetry
It is shown that the Sigma-Omega model which is widely used in the study of
nuclear relativistic many-body problem can exactly be treated as an Abelian
massive gauge field theory. The quantization of this theory can perfectly be
performed by means of the general methods described in the quantum gauge field
theory. Especially, the local U(1) gauge symmetry of the theory leads to a
series of Ward-Takahashi identities satisfied by Green's functions and proper
vertices. These identities form an uniquely correct basis for the
renormalization of the theory. The renormalization is carried out in the
mass-dependent momentum space subtraction scheme and by the renormalization
group approach. With the aid of the renormalization boundary conditions, the
solutions to the renormalization group equations are given in definite
expressions without any ambiguity and renormalized S-matrix elememts are
exactly formulated in forms as given in a series of tree diagrams provided that
the physical parameters are replaced by the running ones. As an illustration of
the renormalization procedure, the one-loop renormalization is concretely
carried out and the results are given in rigorous forms which are suitable in
the whole energy region. The effect of the one-loop renormalization is examined
by the two-nucleon elastic scattering.Comment: 32 pages, 17 figure
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