24 research outputs found
Near horizon data and physical charges of extremal AdS black holes
We compute the physical charges and discuss the properties of a large class
of five-dimensional extremal AdS black holes by using the near horizon data.
Our examples include baryonic and electromagnetic black branes, as well as
supersymmetric spinning black holes. In the presence of the gauge Chern-Simons
term, the five-dimensional physical charges are the Page charges. We carry out
the near horizon analysis and compute the four-dimensional charges of the
corresponding black holes by using the entropy function formalism and show that
they match the Page charges.Comment: 1+19 page
NSR superstring measures in genus 5
Currently there are two proposed ansatze for NSR superstring measures: the
Grushevsky ansatz and the OPSMY ansatz, which for genera g<=4 are known to
coincide. However, neither the Grushevsky nor the OPSMY ansatz leads to a
vanishing two point function in genus four, which can be constructed from the
genus five expressions for the respective ansatze. This is inconsistent with
the known properties of superstring amplitudes.
In the present paper we show that the Grushevsky and OPSMY ansatze do not
coincide in genus five. Then, by combining these ansatze, we propose a new
ansatz for genus five, which now leads to a vanishing two-point function in
genus four. We also show that one cannot construct an ansatz from the currently
known forms in genus 6 that satisfies all known requirements for superstring
measures.Comment: several correction
The fate of Newton's law in brane-world scenarios
We consider brane-world scenarios embedded into string theory. We find that
the D-brane backreaction induces a large increase in the open string's proper
length. Consequently the stringy nature of elementary particles can be detected
at distances much larger than the fundamental string scale. As an example, we
compute the gravitational potential between two open strings ending on
backreacting D3-branes in four-dimensional compactifications of type II string
theory. We find that the Newtonian potential receives a correction that goes
like 1/r but that is not proportional to the inertial masses of the open
strings, implying a violation of the equivalence principle in the effective
gravitational theory. This stringy correction is screened by thermal effects
when the distance between the strings is greater than the inverse temperature.
This suggests new experimental tests for many phenomenological models in type
II string theory.Comment: 8 pages, 3 figure
Phase diagram of the D3/D5 system in a magnetic field and a BKT transition
We study the full temperature and chemical potential dependence of the D3/D5
2+1 dimensional theory in the presence of a magnetic field. The theory displays
separate transitions associated with chiral symmetry breaking and melting of
the bound states. We display the phase diagram which has areas with first and
second order transitions meeting at two critical points similar to that of the
D3/D7 system. In addition there is the recently reported BKT transition at zero
temperature leading to distinct structure at low temperatures.Comment: 5 pages, 3 figures, V2: references adde
S-duality of color-ordered amplitudes
Recently, it has been proposed that the S-matrix elements on the world volume
of an abelian D-brane are consistent with the Ward identity associated with
the S-duality. In this paper we extend this study to the case of multiple
D-branes. We speculate that the S-matrix elements are consistent with the
S-dual Ward identity irrespective of the ordering of the external states.
Imposing this symmetry on the particular case of the S-matrix element of one
Kalb-Ramond, one transverse scalar and two nonabelian gauge bosons, we will
find the linear S-duality transformation of the commutator of two nonabelian
gauge field strengths. Using this transformation and the standard S-duality
transformations of the supergravity fields, all other nonabelian S-matrix
elements of one closed and three open string states can be found by the
S-duality proposal. We will show that the predicted S-matrix elements are
reproduced exactly by explicit calculations.Comment: 20 pages, latex file, no figure, v3: The study of nonabelian S-matrix
element of one closed and three open strings has been added in favor of the
S-duality proposal,v4:the title is changed, the version appears in np
Yangian symmetry in deformed WZNW models on squashed spheres
We introduce a deformation of the Wess-Zumino-Novikov-Witten model with
three-dimensional squashed sphere target space. We show how with an appropriate
choice of Wess--Zumino and boundary terms it is possible to construct an
infinite family of conserved charges realizing an SU(2) Yangian. Finally we
discuss the running of the squashing parameter under renormalization group
flow.Comment: 12 pages, 1 figure, references adde
Hybrid classical integrability in squashed sigma models
We show that SU(2)_L Yangian and q-deformed SU(2)_R symmetries are realized
in a two-dimensional sigma model defined on a three-dimensional squashed
sphere. These symmetries enable us to develop the two descriptions to describe
its classical dynamics, 1) rational and 2) trigonometric descriptions. The
former 1) is based on the SU(2)_L symmetry and the latter 2) comes from the
broken SU(2)_R symmetry. Each of the Lax pairs constructed in both ways leads
to the same equations of motion. The two descriptions are related one another
through a non-local map.Comment: 12 pages, LaTeX, typos corrected and references added, further
clarification adde
On the GUT scale of F-Theory SU(5)
In F-theory GUTs, threshold corrections from Kaluza-Klein massive modes
arising from gauge and matter multiplets play an important role in the
determination of the weak mixing angle and the strong gauge coupling of the
effective low energy model. In this letter we further explore the induced
modifications on the gauge couplings running and the GUT scale. In particular,
we focus on the KK-contributions from matter curves and analyse the conditions
on the chiral and Higgs matter spectrum which imply a GUT scale consistent with
the minimal unification scenario. As an application, we present an explicit
computation of these thresholds for matter fields residing on specific
non-trivial Riemann surfaces.Comment: 21 page
Higher Loop Spin Field Correlators in Various Dimensions
We compute higher-point superstring correlators involving spin fields in
various even space-time dimensions D at tree-level and to arbitrary loop order.
This generalizes previous work in D=4 space-time dimensions. The main focus are
D=6,8 and D=10 superstring compactifications for which correlation functions
with four and more spin fields are computed. More precisely, we present every
non-vanishing six-point function. A number of results can even be derived for
arbitrary D. A closed formula for the correlators with any
number of fermions psi and two spin fields S in D space-time dimensions is
given for arbitrary genus. Moreover, in D=6 and for arbitrary genus, we find a
general formula for the correlators . The latter serve as
basic building blocks to construct higher-point fermionic correlation
functions. In D=8 we can profit from the SO(8)-triality to derive further
tree-level correlators with a large numbers of spin fields.Comment: 47 pages, 1 figure; v2: typos corrected; submitted to JHE
Existence of Dyons in Minimally Gauged Skyrme Model via Constrained Minimization
We prove the existence of electrically and magnetically charged particlelike
static solutions, known as dyons, in the minimally gauged Skyrme model
developed by Brihaye, Hartmann, and Tchrakian. The solutions are spherically
symmetric, depend on two continuous parameters, and carry unit monopole and
magnetic charges but continuous Skyrme charge and non-quantized electric charge
induced from the 't Hooft electromagnetism. The problem amounts to obtaining a
finite-energy critical point of an indefinite action functional, arising from
the presence of electricity and the Minkowski spacetime signature. The
difficulty with the absence of the Higgs field is overcome by achieving
suitable strong convergence and obtaining uniform decay estimates at singular
boundary points so that the negative sector of the action functional becomes
tractable.Comment: 24 page