345 research outputs found
A Calculation of the plane wave string Hamiltonian from N=4 super-Yang-Mills theory
Berenstein, Maldacena, and Nastase have proposed, as a limit of the strong
form of the AdS/CFT correspondence, that string theory in a particular plane
wave background is dual to a certain subset of operators in the N=4
super-Yang-Mills theory. Even though this is a priori a strong/weak coupling
duality, the matrix elements of the string theory Hamiltonian, when expressed
in gauge theory variables, are analytic in the 't Hooft coupling constant. This
allows one to conjecture that, like the masses of excited string states, these
can be recovered using perturbation theory in Yang-Mills theory.
In this paper we identify the difference between the generator of scale
transformations and a particular U(1) R-symmetry generator as the operator dual
to the string theory Hamiltonian for nonvanishing string coupling. We compute
its matrix elements and find that they agree with the string theory prediction
provided that the state-operator map is modified for nonvanishing string
coupling. We construct this map explicitly and calculate the anomalous
dimensions of the new operators. We identify the component arising from the
modification of the state-operator map with the contribution of the string
theory contact terms to the masses of string states.Comment: 38 pages, Latex; v2: Comparison with string theory changed in light
of corrections to string theory results in hep-th/0206073 v3; state-operator
map modified; Physical interpretation and conclusions unchange
BMN operators with vector impurities, Z_2 symmetry and pp-waves
We calculate the coefficients of three-point functions of BMN operators with
two vector impurities. We find that these coefficients can be obtained from
those of the three-point functions of scalar BMN operators by interchanging the
coefficient for the symmetric-traceless representation with the coefficient for
the singlet. We conclude that the Z_2 symmetry of the pp-wave string theory is
not manifest at the level of field theory three-point correlators.Comment: 25 pages, 7 figures. v1: A reference and a footnote added; v2: New
contributions found, Z_2 symmetry lost in 3-point function
DLCQ String Spectrum from SYM Theory
We study non planar corrections to the spectrum of operators in the
supersymmetric Yang Mills theory which are dual to string
states in the maximally supersymmetric pp-wave background with a {\em compact}
light-cone direction. The existence of a positive definite discrete light-cone
momentum greatly simplifies the operator mixing problem. We give some examples
where the contribution of all orders in non-planar diagrams can be found
analytically. On the string theory side this corresponds to finding the
spectrum of a string state to all orders in string loop corrections.Comment: 35 pages, no figure
30 Doradus - a Template for "Real Starbursts"?
30 Doradus is the closest massive star forming region and the best studied
template of a starburst. In this conference paper we first summarize the
properties of 30 Doradus and its stellar core, R136. We discuss the effects of
insufficient spatial resolution and cluster density profiles on dynamical mass
estimates of super star clusters, and show that their masses can be easily
overestimated by a factor of ten or more. From a very simple model, with
R136-like clusters as representative building blocks, we estimate typical
luminosities of the order 10^11 L_o for starburst galaxies.Comment: To be published in "Starbursts: From 30 Doradus to Lyman Break
Galaxies", eds. R. de Grijs & R.M. Gonzalez Delgad
Chiral primary cubic interactions from pp-wave supergravity
We explicitly construct cubic interaction light-cone Hamiltonian for the
chiral primary system involving the metric fields and the self-dual four-form
fields in the IIB pp-wave supergravity. The background fields representing
pp-waves exhibit SO(4)*SO(4)*Z_2 invariance. It turns out that the interaction
Hamiltonian is precisely the same as that for the dilaton-axion system, except
for the fact that the chiral primary system fields have the opposite parity to
that of the dilaton-axion fields under the Z_2 transformation that exchanges
two SO(4)'s.Comment: 14 pages, A few comments are adde
Conformal Dimensions of Two-Derivative BMN Operators
We compute the anomalous dimensions of BMN operators with two covariant
derivative impurities at the planar level up to first order in the effective
coupling lambda'. The result equals those for two scalar impurities as well as
for mixed scalar and vector impurities given in the literature. Though the
results are the same, the computation is very different from the scalar case.
This is basically due to the existence of a non-vanishing overlap between the
derivative impurity and the ``background'' field Z. We present details of these
differences and their consequences.Comment: 27 pages, v2: references added, minor change
On light-cone SFT contact terms in a plane wave
Testing the BMN correspondence at non-zero string coupling g_s requires a
one-loop string field theory calculation. At order g_s^2, matrix elements of
the light-cone string field theory Hamiltonian between single-string states
receive two contributions: the iterated cubic interaction, and a contact term
{Q, Q} whose presence is dictated by supersymmetry. In this paper we calculate
the leading large mu p^+ alpha' contribution from both terms for the set of
intermediate states with two string excitations. We find precise agreement with
the basis-independent order g_2^2 results from gauge theory.Comment: 15 pages, 1 figur
Strings in the near plane wave background and AdS/CFT
We study the AdS/CFT correspondence for string states which flow into plane
wave states in the Penrose limit. Leading finite radius corrections to the
string spectrum are compared with scaling dimensions of finite R-charge
BMN-like operators. We find agreement between string and gauge theory results.Comment: 35 pages, 13 eps figures v2: minor corrections, references adde
Local Commutativity and Causality in Interacting PP-wave String Field Theory
In this paper, we extend our previous study of causality and local
commutativity of string fields in the pp-wave lightcone string field theory to
include interaction. Contrary to the flat space case result of Lowe,
Polchinski, Susskind, Thorlacius and Uglum, we found that the pp-wave
interaction does not affect the local commutativity condition. Our results show
that the pp-wave lightcone string field theory is not continuously connected
with the flat space one. We also discuss the relation between the condition of
local commutativity and causality. While the two notions are closely related in
a point particle theory, their relation is less clear in string theory. We
suggest that string local commutativity may be relevant for an operational
defintion of causality using strings as probes.Comment: Latex, JHEP3.cls, 18 pages, no figures. v2: add comments about the
UV-IR mixing effect displayed in our result. version to appear in JHE
Divergence Cancellation and Loop Corrections in String Field Theory on a Plane Wave Background
We investigate the one-loop energy shift E to certain two-impurity string
states in light-cone string field theory on a plane wave background. We find
that there exist logarithmic divergences in the sums over intermediate mode
numbers which cancel between the cubic Hamiltonian and quartic ``contact
term''. Analyzing the impurity non-conserving channel we find that the
non-perturbative, order g_2^2 sqrt(lambda') contribution to E/mu predicted in
hep-th/0211220 is in fact an artifact of these logarithmic divergences and
vanishes with them, leaving an order g_2^2 lambda' contribution. Exploiting the
supersymmetry algebra, we present a form for the energy shift which appears to
be manifestly convergent and free of non-perturbative terms. We use this form
to argue that E/mu receives order g_2^2 lambda' contributions at every order in
intermediate state impurities.Comment: 27 pages; added references, acknowledgments, missing normalization in
equations 2.3 - 2.8, also cleaned up notation, and added a few footnote
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