173 research outputs found
Non-critical, near extremal AdS_6 background as a holographic laboratory of four dimensional YM theory
We study certain properties of the low energy regime of a theory which
resembles four dimensional YM theory in the framework of a non-critical
holographic gravity dual. We use for the latter the near extremal
non-critical SUGRA. We extract the glueball spectra that associates with the
fluctuations of the dilaton, one form and the graviton and compare the results
to those of the critical near extremal model and lattice simulations. We
show an area law behavior for the Wilson loop and screening for the 't Hooft
loop. The Luscher term is found to be . We derive the
Regge trajectories of glueballs associated with the spinning folded string
configurations.Comment: 25 pages, JHEP styl
Glueballs, symmetry breaking and axionic strings in non-supersymmetric deformations of the Klebanov-Strassler background
We obtain an analytic solution for an axionic non-supersymmetric deformation
of the warped deformed conifold. This allows us to study D-strings in the
infrared limit of non-supersymmetric deformations of the Klebanov-Strassler
background. They are interpreted as axionic strings in the dual field theory.
Following the arguments of [hep-th/0405282], the axion is a massless
pseudo-scalar glueball which is present in the supergravity fluctuation
spectrum and it is interpreted as the Goldstone boson of the spontaneously
broken U(1) baryon number symmetry, being the gauge theory on the baryonic
branch. Besides, we briefly discuss about the Pando Zayas-Tseytlin solution
where the SU(2) \times SU(2) global symmetry is spontaneously broken. This
background has been conjectured to be on the mesonic branch of the gauge
theory.Comment: 30 pages; V2: minor corrections; V3: section 3 corrected and
misprints corrected to match version published in JHE
Glueball operators and the microscopic approach to N=1 gauge theories
We explain how to generalize Nekrasov's microscopic approach to N=2 gauge
theories to the N=1 case, focusing on the typical example of the U(N) theory
with one adjoint chiral multiplet X and an arbitrary polynomial tree-level
superpotential Tr W(X). We provide a detailed analysis of the generalized
glueball operators and a non-perturbative discussion of the Dijkgraaf-Vafa
matrix model and of the generalized Konishi anomaly equations. We compute in
particular the non-trivial quantum corrections to the Virasoro operators and
algebra that generate these equations. We have performed explicit calculations
up to two instantons, that involve the next-to-leading order corrections in
Nekrasov's Omega-background.Comment: 38 pages, 1 figure and 1 appendix included; v2: typos and the list of
references corrected, version to appear in JHE
Holography and Thermodynamics of 5D Dilaton-gravity
The asymptotically-logarithmically-AdS black-hole solutions of 5D dilaton
gravity with a monotonic dilaton potential are analyzed in detail. Such
theories are holographically very close to pure Yang-Mills theory in four
dimensions. The existence and uniqueness of black-hole solutions is shown. It
is also shown that a Hawking-Page transition exists at finite temperature if
and only if the potential corresponds to a confining theory. The physics of the
transition matches in detail with that of deconfinement of the Yang-Mills
theory. The high-temperature phase asymptotes to a free gluon gas at high
temperature matching the expected behavior from asymptotic freedom. The thermal
gluon condensate is calculated and shown to be crucial for the existence of a
non-trivial deconfining transition. The condensate of the topological charge is
shown to vanish in the deconfined phase.Comment: LaTeX, 61 pages (main body) + 58 pages (appendix), 25 eps figures.
Revised version, published in JHEP. Two equations added in Section 7.4; typos
corrected; references adde
Exploring improved holographic theories for QCD: Part I
Various holographic approaches to QCD in five dimensions are explored using
input both from the putative non-critical string theory as well as QCD. It is
argued that a gravity theory in five dimensions coupled to a dilaton and an
axion may capture the important qualitative features of pure QCD. A part of the
higher alpha' corrections are resummed into a dilaton potential. The potential
is shown to be in one-to-one correspondence with the exact beta-function of
QCD, and its knowledge determines the full structure of the vacuum solution.
The geometry near the UV boundary is that of AdS_5 with logarithmic corrections
reflecting the asymptotic freedom of QCD. We find that all relevant confining
backgrounds have an IR singularity of the "good" kind that allows unambiguous
spectrum computations. Near the singularity the 't Hooft coupling is driven to
infinity. Asymptotically linear glueball masses can also be achieved. The
classification of all confining asymptotics, the associated glueball spectra
and meson dynamics are addressed in a companion paper, ArXiv:0707.1349Comment: 37+23 pages, 11 figures. (v3) Some clarifications and typo
corrections. Journal versio
Flavor brane on the baryonic branch of moduli space
We study an extra flavor in the cascading SU((k+1)M)xSU(k M) gauge theory by
adding probe D7-brane to the geometry. By finding a solution to the
kappa-symmetry equation we establish that the D7-brane is mutually
supersymmetric with the background everywhere on the baryonic branch of moduli
space. We also discuss possible applications of this result.Comment: 15 pages; v2 typo corrected, references adde
Wilson Loop, Regge Trajectory and Hadron Masses in a Yang-Mills Theory from Semiclassical Strings
We compute the one-loop string corrections to the Wilson loop, glueball Regge
trajectory and stringy hadron masses in the Witten model of non supersymmetric,
large-N Yang-Mills theory. The classical string configurations corresponding to
the above field theory objects are respectively: open straight strings, folded
closed spinning strings, and strings orbiting in the internal part of the
supergravity background. For the rectangular Wilson loop we show that besides
the standard Luescher term, string corrections provide a rescaling of the field
theory string tension. The one-loop corrections to the linear glueball Regge
trajectories render them nonlinear with a positive intercept, as in the
experimental soft Pomeron trajectory. Strings orbiting in the internal space
predict a spectrum of hadronic-like states charged under global flavor
symmetries which falls in the same universality class of other confining
models.Comment: 52 pages, latex 3 times, v3: references adde
Can holography reproduce the QCD Wilson line?
Recently a remarkable agreement was found between lattice simulations of long
Wilson lines and behavior of the Nambu Goto string in flat space-time. However,
the latter fails to fit the short distance behavior since it admits a tachyonic
mode for a string shorter than a critical length. In this paper we examine the
question of whether a classical holographic Wilson line can reproduce the
lattice results for Wilson lines of any length. We determine the condition on
the the gravitational background to admit a Coulombic potential at short
distances. We analyze the system using three different renormalization schemes.
We perform an explicit best fit comparison of the lattice results with the
holographic models based on near extremal D3 and D4 branes, non-critical near
extremal AdS6 model and the Klebanov Strassler model. We find that all the
holographic models examined admit after renormalization a constant term in the
potential. We argue that the curves of the lattice simulation also have such a
constant term and we discuss its physical interpretation
- âŠ