589 research outputs found
Stringy effect of the holographic correspondence for Dp-brane backgrounds
Based on the holographic conjecture for superstrings on Dp-brane backgrounds
and the dual (p+1)-dimensional gauge theory () given in
hep-th/0308024 and hep-th/0405203, we continue the study of superstring
amplitudes including string higher modes (). We give a prediction to
the two-point functions of operators with large R-charge J. The effect of
stringy modes do not appear as the form of anomalous dimensions except for p=3.
Instead, it gives non-trivial correction to the two-point functions for
supergravity modes. For p=4, the scalar two-point functions for any n behave
like free fields of the effective dimension d_{eff}=6 in the infra-red limit.Comment: 23 pages, typos correcte
Some comments on spacelike minimal surfaces with null polygonal boundaries in
We discuss some geometrical issues related to spacelike minimal surfaces in
with null polygonal boundaries at conformal infinity. In particular for
, two holomorphic input functions for the Pohlmeyer reduced system are
identified. This system contains two coupled differential equations for two
functions and , related to curvature and
torsion of the surface. Furthermore, we conjecture that, for a polynomial
choice of the two holomorphic functions, the relative positions of their zeros
encode the conformal invariant data of the boundary null -gon.Comment: 13 pages, a note and references added, version to appear in JHE
Semiclassical correlators of three states with large S^5 charges in string theory in AdS_5 x S^5
We consider semiclassical computation of 3-point correlation functions of
(BPS or non-BPS) string states represented by vertex operators carrying large
charges in S5. We argue that the AdS5 part of the construction of relevant
semiclassical solution involves the two basic ingredients: (i) configuration of
three glued geodesics in AdS2 suggested by Klose and McLoughlin in
arXiv:1106.0495 and (ii) a particular Schwarz-Christoffel map of the 3-geodesic
solution in cylindrical (tau, sigma) domain into the complex plane with three
marked points. This map is constructed using the expression for the AdS2 string
stress tensor which is uniquely determined by the 3 scaling dimensions as noted
by Janik and Wereszczynski in arXiv:1109.6262 (our solution, however, is
different from theirs). We also find the S5 part of the solution and thus the
full expression for the semiclassical part of the 3-point correlator for
several examples: extremal and non-extremal correlators of BPS states and a
particular correlator of "small" circular spinning strings in S3 part of S5. We
demonstrate that for the BPS correlators the results agree with the large
charge limit of the corresponding supergravity and free gauge theory
expressions.Comment: 43 pages, 4 figures; v2: minor corrections; v3: comments added at the
end of section 3 and in section 5; v4: minor corrections; v5: discussion in
subsection 3.3 correcte
A note on string solutions in AdS_3
We systematically search for classical open string solutions in AdS_3 within
the general class expressed by elliptic functions (i.e., the genus-one
finite-gap solutions). By explicitly solving the reality and Virasoro
conditions, we give a classification of the allowed solutions. When the
elliptic modulus degenerates, we find a class of solutions with six null
boundaries, among which two pairs are collinear. By adding the S^1 sector, we
also find four-cusp solutions with null boundaries expressed by the elliptic
functions.Comment: 17 pages, 1 figure; (v2) added 1 figure and discussion on solutions
with 6 null boundaries; (v3) corrected equation numbers; (v4) added comment
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
Existence of Dynamical Scaling in the Temporal Signal of Time Projection Chamber
The temporal signals from a large gas detector may show dynamical scaling due
to many correlated space points created by the charged particles while passing
through the tracking medium. This has been demonstrated through simulation
using realistic parameters of a Time Projection Chamber (TPC) being fabricated
to be used in ALICE collider experiment at CERN. An interesting aspect of this
dynamical behavior is the existence of an universal scaling which does not
depend on the multiplicity of the collision. This aspect can be utilised
further to study physics at the device level and also for the online monitoring
of certain physical observables including electronics noise which are a few
crucial parameters for the optimal TPC performance.Comment: 5 pages, 6 figure
Non-perturbative contributions to the plane-wave string mass matrix
D-instanton contributions to the mass matrix of arbitrary excited string
states of type IIB string theory in the maximally supersymmetric plane-wave
background are calculated to leading order in the string coupling using a
supersymmetric light-cone boundary state formalism. The explicit
non-perturbative dependence of the mass matrix on the complex string coupling,
the plane-wave mass parameter and the mode numbers of the excited states is
determined.Comment: 25 pages, 1 figure. v3: corrected minor typos, added referenc
On semiclassical approximation for correlators of closed string vertex operators in AdS/CFT
We consider the 2-point function of string vertex operators representing
string state with large spin in AdS_5. We compute this correlator in the
semiclassical approximation and show that it has the expected (on the basis of
state-operator correspondence) form of the strong-coupling limit of the 2-point
function of single trace minimal twist operators in gauge theory. The
semiclassical solution representing the stationary point of the path integral
with two vertex operator insertions is found to be related to the large spin
limit of the folded spinning string solution by a euclidean continuation,
transformation to Poincare coordinates and conformal map from cylinder to
complex plane. The role of the source terms coming from the vertex operator
insertions is to specify the parameters of the solution in terms of quantum
numbers (dimension and spin) of the corresponding string state. Understanding
further how similar semiclassical methods may work for 3-point functions may
shed light on strong-coupling limit of the corresponding correlators in gauge
theory as was recently suggested by Janik et al in arXiv:1002.4613.Comment: 19 pages, 1 figure; minor corrections, references added, footnote
below eq. (4.5) adde
A Ring Shaped Embedded Young Stellar (Proto)Cluster
We present sub-arcsec (FWHM ~ 0.5") J, H, K and L' images of a young stellar
cluster associated with a candidate massive protostar IRAS22134+5834. The
observations reveal a centrally symmetric, flattened cluster enclosing a
central dark region. The central dark region is possibly a cavity within the
flattened cluster. It is surrounded by a ring composed of 5 bright stars and
the candidate massive protostar IRAS22134+5834. We construct JHKL' color-color
and HK color-magnitude diagrams to identify the young stellar objects and
estimate their spectral types. All the bright stars in the ring are found to
have intrinsic infrared excess emission and are likely to be early to late B
type stars. We estimate an average foreground extinction to the cluster of A_v
\~ 5mag and individual extinctions to the bright stars in the range A_v ~
20-40mag indicating possible cocoons surrounding each massive star. This ring
of bright stars is devoid of any HII region. It is surrounded by an embedded
cluster making this an example of a (proto)cluster that is in one of the
dynamically least relaxed states. These observations are consistent with the
recent non-axisymmetric calculations of Li & Nakamura, who present a star
formation scenario in which a magnetically subcritical cloud fragments into
multiple magnetically supercritical cores, leading to the formation of small
stellar groups.Comment: 13 pages in preprint format, 3 figures, 1 tabl
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