1,346 research outputs found
ABJ(M) Chiral Primary Three-Point Function at Two-loops
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Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.archiveprefix: arXiv primaryclass: hep-th reportnumber: QMUL-PH-14-10 slaccitation: %%CITATION = ARXIV:1404.1117;%%archiveprefix: arXiv primaryclass: hep-th reportnumber: QMUL-PH-14-10 slaccitation: %%CITATION = ARXIV:1404.1117;%%archiveprefix: arXiv primaryclass: hep-th reportnumber: QMUL-PH-14-10 slaccitation: %%CITATION = ARXIV:1404.1117;%%Article funded by SCOAP
Self-similar solutions with fat tails for Smoluchowski's coagulation equation with locally bounded kernels
The existence of self-similar solutions with fat tails for Smoluchowski's
coagulation equation has so far only been established for the solvable and the
diagonal kernel. In this paper we prove the existence of such self-similar
solutions for continuous kernels that are homogeneous of degree and satisfy . More precisely,
for any we establish the existence of a continuous weak
self-similar profile with decay as
Self-Similarity for Ballistic Aggregation Equation
We consider ballistic aggregation equation for gases in which each particle
is iden- ti?ed either by its mass and impulsion or by its sole impulsion. For
the constant aggregation rate we prove existence of self-similar solutions as
well as convergence to the self-similarity for generic solutions. For some
classes of mass and/or impulsion dependent rates we are also able to estimate
the large time decay of some moments of generic solutions or to build some new
classes of self-similar solutions
Far-from-equilibrium Sheared Colloidal Liquids: Disentangling Relaxation, Advection, and Shear-induced Diffusion
Using high-speed confocal microscopy, we measure the particle positions in a
colloidal suspension under large amplitude oscillatory shear. Using the
particle positions we quantify the in situ anisotropy of the pair-correlation
function -- a measure of the Brownian stress. From these data, we find two
distinct types of responses as the system crosses over from equilibrium to
far-from-equilibrium states. The first is a nonlinear amplitude saturation that
arises from shear-induced advection, while the second is a linear frequency
saturation due to competition between suspension relaxation and shear rate. In
spite of their different underlying mechanisms, we show that all the data can
be scaled onto a master curve that spans the equilibrium and
far-from-equilibrium regimes, linking small amplitude oscillatory to continuous
shear. This observation illustrates a colloidal analog of the Cox-Merz rule and
its microscopic underpinning. Brownian Dynamics simulations show that
interparticle interactions are sufficient for generating both experimentally
observed saturations
Heavy Quarkonium in a weakly-coupled quark-gluon plasma below the melting temperature
We calculate the heavy quarkonium energy levels and decay widths in a
quark-gluon plasma, whose temperature T and screening mass m_D satisfy the
hierarchy m alpha_s >> T >> m alpha_s^2 >> m_D (m being the heavy-quark mass),
at order m alpha_s^5. We first sequentially integrate out the scales m, m
alpha_s and T, and, next, we carry out the calculations in the resulting
effective theory using techniques of integration by regions. A collinear region
is identified, which contributes at this order. We also discuss the
implications of our results concerning heavy quarkonium suppression in heavy
ion collisions.Comment: 25 pages, 2 figure
Self-similar chain conformations in polymer gels
We use molecular dynamics simulations to study the swelling of randomly
end-cross-linked polymer networks in good solvent conditions. We find that the
equilibrium degree of swelling saturates at Q_eq = N_e**(3/5) for mean strand
lengths N_s exceeding the melt entanglement length N_e. The internal structure
of the network strands in the swollen state is characterized by a new exponent
nu=0.72. Our findings are in contradiction to de Gennes' c*-theorem, which
predicts Q_eq proportional N_s**(4/5) and nu=0.588. We present a simple Flory
argument for a self-similar structure of mutually interpenetrating network
strands, which yields nu=7/10 and otherwise recovers the classical Flory-Rehner
theory. In particular, Q_eq = N_e**(3/5), if N_e is used as effective strand
length.Comment: 4 pages, RevTex, 3 Figure
Partial domain wall partition functions
We consider six-vertex model configurations on an n-by-N lattice, n =< N,
that satisfy a variation on domain wall boundary conditions that we define and
call "partial domain wall boundary conditions". We obtain two expressions for
the corresponding "partial domain wall partition function", as an
(N-by-N)-determinant and as an (n-by-n)-determinant. The latter was first
obtained by I Kostov. We show that the two determinants are equal, as expected
from the fact that they are partition functions of the same object, that each
is a discrete KP tau-function, and, recalling that these determinants represent
tree-level structure constants in N=4 SYM, we show that introducing 1-loop
corrections, as proposed by N Gromov and P Vieira, preserves the determinant
structure.Comment: 30 pages, LaTeX. This version, which appeared in JHEP, has an
abbreviated abstract and some minor stylistic change
Thermal width and gluo-dissociation of quarkonium in pNRQCD
The thermal width of heavy-quarkonium bound states in a quark-gluon plasma
has been recently derived in an effective field theory approach. Two phenomena
contribute to the width: the Landau damping phenomenon and the break-up of a
colour-singlet bound state into a colour-octet heavy quark-antiquark pair by
absorption of a thermal gluon. In the paper, we investigate the relation
between the singlet-to-octet thermal break-up and the so-called
gluo-dissociation, a mechanism for quarkonium dissociation widely used in
phenomenological approaches. The gluo-dissociation thermal width is obtained by
convoluting the gluon thermal distribution with the cross section of a gluon
and a 1S quarkonium state to a colour octet quark-antiquark state in vacuum, a
cross section that at leading order, but neglecting colour-octet effects, was
computed long ago by Bhanot and Peskin. We will, first, show that the effective
field theory framework provides a natural derivation of the gluo-dissociation
factorization formula at leading order, which is, indeed, the singlet-to-octet
thermal break-up expression. Second, the singlet-to-octet thermal break-up
expression will allow us to improve the Bhanot--Peskin cross section by
including the contribution of the octet potential, which amounts to include
final-state interactions between the heavy quark and antiquark. Finally, we
will quantify the effects due to final-state interactions on the
gluo-dissociation cross section and on the quarkonium thermal width.Comment: 17 pages, 6 figure
Three-point function of semiclassical states at weak coupling
We give the derivation of the previously announced analytic expression for
the correlation function of three heavy non-BPS operators in N=4
super-Yang-Mills theory at weak coupling. The three operators belong to three
different su(2) sectors and are dual to three classical strings moving on the
sphere. Our computation is based on the reformulation of the problem in terms
of the Bethe Ansatz for periodic XXX spin-1/2 chains. In these terms the three
operators are described by long-wave-length excitations over the ferromagnetic
vacuum, for which the number of the overturned spins is a finite fraction of
the length of the chain, and the classical limit is known as the Sutherland
limit. Technically our main result is a factorized operator expression for the
scalar product of two Bethe states. The derivation is based on a fermionic
representation of Slavnov's determinant formula, and a subsequent bosonisation.Comment: 28 pages, 5 figures, cosmetic changes and more typos corrected in v
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