775 research outputs found
Debye mass from domainwalls and dimensionally reduced phase diagram
To measure the Debye mass in dimensionally reduced QCD for we
replace in the correlator of two Polyakov loops one of the loops by a wall
triggered by a dimensionally reduced twist. The phase diagram for has
R-parity broken in part of the Higgs phase.Comment: LATTICE98(hightemp
Bosonization as Duality
We show that bosonization in two dimensions can be derived as a special case
of the duality transformations that have recently been used to good effect in
string theory. This allows the construction of the bosonic counterpart of any
fermionic theory simply by `following your nose' using the standard duality
transformation rules. We work through the bosonization of the Dirac fermion,
the massive and massless Thirring models, and a fermion on a cylindrical
spacetime as illustrative examples.Comment: plain TeX, 21 page
Monopoles, noncommutative gauge theories in the BPS limit and some simple gauge groups
For three conspicuous gauge groups, namely, SU(2), SU(3) and SO(5), and at
first order in the noncommutative parameter matrix h\theta^{\mu\nu}, we
construct smooth monopole --and, some two-monopole-- fields that solve the
noncommutative Yang-Mills-Higgs equations in the BPS limit and that are formal
power series in h\theta^{\mu\nu}. We show that there exist noncommutative BPS
(multi-)monopole field configurations that are formal power series in
h\theta^{\mu\nu} if, and only if, two a priori free parameters of the
Seiberg-Witten map take very specific values. These parameters, that are not
associated to field redefinitions nor to gauge transformations, have thus
values that give rise to sharp physical effects.Comment: 30 pages, no figure
Properties of the deconfining phase transition in SU(N) gauge theories
We extend our earlier investigation of the finite temperature deconfinement
transition in SU(N) gauge theories, with the emphasis on what happens as N->oo.
We calculate the latent heat in the continuum limit, and find the expected
quadratic in N behaviour at large N. We confirm that the phase transition,
which is second order for SU(2) and weakly first order for SU(3), becomes
robustly first order for N>3 and strengthens as N increases. As an aside, we
explain why the SU(2) specific heat shows no sign of any peak as T is varied
across what is supposedly a second order phase transition. We calculate the
effective string tension and electric gluon masses at T=Tc confirming the
discontinuous nature of the transition for N>2. We explicitly show that the
large-N `spatial' string tension does not vary with T for T<Tc and that it is
discontinuous at T=Tc. For T>Tc it increases as T-squared to a good
approximation, and the k-string tension ratios closely satisfy Casimir Scaling.
Within very small errors, we find a single Tc at which all the k-strings
deconfine, i.e. a step-by-step breaking of the relevant centre symmetry does
not occur. We calculate the interface tension but are unable to distinguish
between linear or quadratic in N variations, each of which can lead to a
striking but different N=oo deconfinement scenario. We remark on the location
of the bulk phase transition, which bounds the range of our large-N
calculations on the strong coupling side, and within whose hysteresis some of
our larger-N calculations are performed.Comment: 50 pages, 14 figure
Interacting Dipoles from Matrix Formulation of Noncommutative Gauge Theories
We study the IR behavior of noncommutative gauge theory in the matrix
formulation. We find that in this approach, the nature of the UV/IR mixing is
easily understood, which allows us to perform a reliable calculation of the
quantum effective action for the long wavelength modes of the noncommutative
gauge field. At one loop, we find that our description is weakly coupled only
in the supersymmetric theory. At two loops, we find non-trivial interaction
terms suggestive of dipole degrees of freedom. These dipoles exhibit a channel
duality reminiscent of string theory.Comment: LaTeX 11 pages, 4 figures; v.2 minor changes and some references
added; v.3 many more technical details added and significantly different
presentation, use REVTeX 4, to appear in PR
The open-charm radiative and pionic decays of molecular charmonium Y(4274)
In this work, we investigate the decay widths and the line shapes of the
open-charm radiative and pionic decays of Y(4274) with the
molecular charmonium assignment. Our calculation
indicates that the decay widths of and
can reach up to 0.05 keV and 0.75 keV,
respectively. In addition, the result of the line shape of the photon spectrum
of shows that there exists a very sharp
peak near the large end point of photon energy. The line shape of the pion
spectrum of is similar to that of the pion
spectrum of , where we also find a very
sharp peak near the large end point of pion energy. According to our
calculation, we suggest further experiments to carry out the search for the
open-charm radiative and pionic decays of Y(4274).Comment: 7 pages, 6 figures, 1 table. Published versio
Super-Hubble de Sitter Fluctuations and the Dynamical RG
Perturbative corrections to correlation functions for interacting theories in
de Sitter spacetime often grow secularly with time, due to the properties of
fluctuations on super-Hubble scales. This growth can lead to a breakdown of
perturbation theory at late times. We argue that Dynamical Renormalization
Group (DRG) techniques provide a convenient framework for interpreting and
resumming these secularly growing terms. In the case of a massless scalar field
in de Sitter with quartic self-interaction, the resummed result is also less
singular in the infrared, in precisely the manner expected if a dynamical mass
is generated. We compare this improved infrared behavior with large-N
expansions when applicable.Comment: 33 pages, 4 figure
A remark on non-Abelian classical kinetic theory
It is known that non-Abelian classical kinetic theory reproduces the Hard
Thermal/Dense Loop (HTL/HDL) effective action of QCD, obtained after
integrating out the hardest momentum scales from the system, as well as the
first higher dimensional operator beyond the HTL/HDL level. We discuss here its
applicability at still higher orders, by comparing the exact classical
effective action obtained in the static limit, with the 1-loop quantum
effective potential. We remark that while correct types of operators arise, the
classical colour algebra reproduces correctly the prefactor of the 4-point
function only for matter in asymptotically high dimensional colour
representations.Comment: 6 page
Dynamics of Baryons from String Theory and Vector Dominance
We consider a holographic model of QCD from string theory, a la Sakai and
Sugimoto, and study baryons. In this model, mesons are collectively realized as
a five-dimensional \ Yang-Mills field and baryons
are classically identified as solitons with a unit Pontryagin number
and electric charges. The soliton is shown to be very small in the large
't Hooft coupling limit, allowing us to introduce an effective field . Its coupling to the mesons are dictated by the soliton structure, and
consists of a direct magnetic coupling to the field strength as well
as a minimal coupling to the gauge field. Upon the dimensional
reduction, this effective action reproduces all interaction terms between
nucleons and an infinite tower of mesons in a manner consistent with the large
expansion. We further find that all electromagnetic interactions, as
inferred from the same effective action via a holographic prescription, are
mediated by an infinite tower of vector mesons, rendering the baryon
electromagnetic form factors completely vector-dominated as well. We estimate
nucleon-meson couplings and also the anomalous magnetic moments, which compare
well with nature.Comment: 65pages, 3 figures, vector mesons and axial-vector mesons are now
canonically normalized (comparisons with data and conclusions unaffected
Phase of the Wilson Line at High Temperature in the Standard Model
We compute the effective potential for the phase of the Wilson line at high
temperature in the standard model to one loop order. Besides the trivial vacua,
there are metastable states in the direction of hypercharge. Assuming
that the universe starts out in such a metastable state at the Planck scale, it
easily persists to the time of the electroweak phase transition, which then
proceeds by an unusual mechanism. All remnants of the metastable state
evaporate about the time of the phase transition.Comment: 4 pages in ReVTeX plus 1 figure; Columbia Univ. preprint CU-TP-63
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