50 research outputs found
AdS Branes Corresponding to Superconformal Defects
We investigate an AdS_4 x L_2 D5-brane in AdS_5 x X_5 space-time, in the
context of AdS/dCFT correspondence. Here, X_5 is a Sasaki-Einstein manifold and
L_2 is a submanifold of X_5. This brane has the same supersymmetry as the
3-dimensional N=1 superconformal symmetry if L_2 is a special Legendrian
submanifold in X_5. In this case, this brane is supposed to correspond to a
superconformal wall defect in 4-dimensional N=4 super Yang-Mills theory. We
construct these new string backgrounds and show they have the correct
supersymmetry, also in the case with non-trivial gauge flux on L_2. The
simplest new example is AdS_4 x T^2 brane in AdS_5 x S^5. We construct the
brane solution expressing the RG flow between two different defects. We also
perform similar analysis for an AdS_3 x L_3 M5-brane in AdS_4 x X_7, for a weak
G_2 manifold X_7 and its submanifold L_3. This system has the same
supersymmetry as 2-dimensional N=(1,0) global superconformal symmetry, if L_3
is an associative submanifold.Comment: 22 pages, LaTeX, 3 figures. v2: typos corrected, references added.
v3: typos correcte
The Enhancon, Black Holes, and the Second Law
We revisit the physics of five-dimensional black holes constructed from D5-
and D1-branes and momentum modes in type IIB string theory compactified on K3.
Since these black holes incorporate D5-branes wrapped on K3, an enhancon locus
appears in the spacetime geometry. With a `small' number of D1-branes, the
entropy of a black hole is maximised by including precisely half as many
D5-branes as there are D1-branes in the black hole. Any attempts to introduce
more D5-branes, and so reduce the entropy, are thwarted by the appearance of
the enhancon locus above the horizon, which then prevents their approach. The
enhancon mechanism thereby acts to uphold the Second Law of Thermodynamics.
This result generalises: For each type of bound state object which can be made
of both types of brane, we show that a new type of enhancon exists at
successively smaller radii in the geometry, again acting to prevent any
reduction of the entropy just when needed. We briefly explore the appearance of
the enhancon in the black hole interior.Comment: 22 pages, 2 figures, latex, epsfig (v2: Fixed trivial typos.
Glueballs of Super Yang-Mills from Wrapped Branes
In this paper we study qualitative features of glueballs in N=1 SYM for
models of wrapped branes in IIA and IIB backgrounds. The scalar mode, 0++ is
found to be a mixture of the dilaton and the internal part of the metric. We
carry out the numerical study of the IIB background. The potential found
exhibits a mass gap and produces a discrete spectrum without any cut-off. We
propose a regularization procedure needed to make these states normalizable.Comment: 22 pages plus a appendixes, 2 figure
Global Drivers on Southern Ocean Ecosystems: Changing Physical Environments and Anthropogenic Pressures in an Earth System
Copyright © 2020 Morley, Abele, Barnes, Cårdenas, Cotté, Gutt, Henley, Höfer, Hughes, Martin, Moffat, Raphael, Stammerjohn, Suckling, Tulloch, Waller and Constable. The manuscript assesses the current and expected future global drivers of Southern Ocean (SO) ecosystems. Atmospheric ozone depletion over the Antarctic since the 1970s, has been a key driver, resulting in springtime cooling of the stratosphere and intensification of the polar vortex, increasing the frequency of positive phases of the Southern Annular Mode (SAM). This increases warm air-flow over the East Pacific sector (Western Antarctic Peninsula) and cold air flow over the West Pacific sector. SAM as well as El Niño Southern Oscillation events also affect the Amundsen Sea Low leading to either positive or negative sea ice anomalies in the west and east Pacific sectors, respectively. The strengthening of westerly winds is also linked to shoaling of deep warmer water onto the continental shelves, particularly in the East Pacific and Atlantic sectors. Air and ocean warming has led to changes in the cryosphere, with glacial and ice sheet melting in both sectors, opening up new ice free areas to biological productivity, but increasing seafloor disturbance by icebergs. The increased melting is correlated with a salinity decrease particularly in the surface 100 m. Such processes could increase the availability of iron, which is currently limiting primary production over much of the SO. Increasing CO2 is one of the most important SO anthropogenic drivers and is likely to affect marine ecosystems in the coming decades. While levels of many pollutants are lower than elsewhere, persistent organic pollutants (POPs) and plastics have been detected in the SO, with concentrations likely enhanced by migratory species. With increased marine traffic and weakening of ocean barriers the risk of the establishment of non-indigenous species is increased. The continued recovery of the ozone hole creates uncertainty over the reversal in sea ice trends, especially in the light of the abrupt transition from record high to record low Antarctic sea ice extent since spring 2016. The current rate of change in physical and anthropogenic drivers is certain to impact the Marine Ecosystem Assessment of the Southern Ocean (MEASO) region in the near future and will have a wide range of impacts across the marine ecosystem
Hidratação enteral em bovinos: avaliação de soluçÔes eletrolĂticas isotĂŽnicas administradas por sonda nasogĂĄstrica em fluxo contĂnuo
Odderon in Gauge/String Duality
At high energies, elastic hadronic cross sections, such as , are dominated by vacuum exchange, which in leading order of
the expansion has been identified as the BFKL Pomeron or its strong AdS
dual the closed string Reggeized graviton \cite{Brower:2006ea}. However the
difference of particle anti-particle cross sections are given by a so-called
Odderon, carrying C = -1 vacuum quantum numbers identified in weak coupling
with odd numbers of exchanged gluons. Here we show that in the dual description
the Odderon is the Reggeized Kalb-Ramond field () in the
Neveu-Schwartz sector of closed string theory. To first order in strong
coupling, the high energy contribution of Odderon is evaluated for Super Yang-Mills by a generalization of the gravity dual analysis for
Pomeron in Ref. \cite{Brower:2006ea}. The consequence of confinement on the
Odderon are estimated in the confining QCD-like hardwall model of
Polchinski and Strassler \cite{Polchinski:2001tt}.Comment: 69 pages, 6 figures. Title change to better reflect the content of
the paper. More discussion added in the Comments section. To be published in
JHE