2,338,120 research outputs found
The Hyperfine Splitting in Charmonium: Lattice Computations Using the Wilson and Clover Fermion Actions
We compute the hyperfine splitting on the lattice,
using both the Wilson and -improved (clover) actions for quenched quarks.
The computations are performed on a lattice at ,
using the same set of 18 gluon configurations for both fermion actions. We find
that the splitting is 1.83\err{13}{15} times larger with the clover action than
with the Wilson action, demonstrating the sensitivity of the spin-splitting to
the magnetic moment term which is present in the clover action. However, even
with the clover action the result is less than half of the physical
mass-splitting. We also compute the decay constants and
, both of which are considerably larger when computed using
the clover action than with the Wilson action. For example for the ratio
we find 0.32\err{1}{2} with the Wilson action
and with the clover action (the physical value is 0.44(2)).Comment: LaTeX file, 8 pages and two postscript figures. Southampton Preprint:
SHEP 91/92-27 Edinburgh Preprint: 92/51
Holography of Wilson-Loop Expectation Values with Local Operator Insertions
We study the expectation values of Wilson-loop operators with the
insertionsof local operators Z^J and Zbar^J with large R-charge J from the bulk
viewpoint of AdS/CFT correspondence. Classical solutions of strings attached to
such deformed Wilson loops at the conformal boundary are constructed and are
applied to the computation of Wilson-loop expectation values. We argue that in
order to have such solutions for general insertions at finite positions in the
base spacetime of the gauge theory, it is crucial to interpret the holographic
correspondence in the semi-classical picture as a tunneling phenomenon, as has
been previously established for holographic computations of correlators of BMN
operators. This also requires to use the Euclideanized AdS background and
Euclidean super Yang-Mills theory.Comment: 16 pages, 5 figures, version to be published in JHEP, no change from
the previous version, only extraneous figure file is remove
The Legacy of Ken Wilson
This is a brief account of the legacy of Ken Wilson in statistical physics,
high energy physics, computing and education.Comment: Written version of a talk given at the Ken Wilson Memorial Session,
StatPhys 25, Seoul, July 2013. To appear in the conference proceedings in J.
Stat. Mec
Holography in the Large J Limit of AdS/CFT Correspondence and Its Applications
We give a brief expository discussion on the holographic correspondence of
correlation functions in the large J limit of AdS/CFT conjecture. We first
review our proposals on the interpretation of the so-called GKPW relation in
the large J limit or BMN limit, which are based upon a tunneling picture in
relating the AdS bulk to its boundary. Some concrete results, explicitly
confirming our picture, are summarized. We then proceed to comment on various
issues related to this subject, such as extension of the present picture to
nonconformal Dp-brane backgrounds, the correlators of deformed Wilson loops,
spinning-string/spin-chain correspondence, and the inclusion of higher
string-loop effects. In particular, as for the deformation of Wilson loops, we
present a typical tunneling world-sheet solution which can be used for direct
derivation of the expectation values of deformed Wilson loops following our
picture.Comment: 21 pages, written version of a talk given at the symposium "Frontiers
of Quantum Science", YITP, Kyoto, Feb. 2005, corrected typos and some minor
revisions of tex
Cusped light-like Wilson loops in gauge theories
We propose and discuss a new approach to the analysis of the correlation
functions which contain light-like Wilson lines or loops, the latter being
cusped in addition. The objects of interest are therefore the light-like Wilson
null-polygons, the soft factors of the parton distribution and fragmentation
functions, high-energy scattering amplitudes in the eikonal approximation,
gravitational Wilson lines, etc. Our method is based on a generalization of the
universal quantum dynamical principle by J. Schwinger and allows one to take
care of extra singularities emerging due to light-like or semi-light-like
cusps. We show that such Wilson loops obey a differential equation which
connects the area variations and renormalization group behavior of those
objects and discuss the possible relation between geometrical structure of the
loop space and area evolution of the light-like cusped Wilson loops.Comment: Invited mini-review article to Physics of Particles and Nuclei. 16
pages, 9 eps figures; v2: references style changed, citations corrected and
update
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