20,236 research outputs found
Holography and chiral Lagrangian
In a wide class of holographic models described by the Yang-Mills and
Chern-Simons terms, we derive all the Chiral Perturbation
Theory low-energy constants. Various model-independent relations exist among
the constants up to this order, generalizing the previously found relations at
order. Some of them can be extended to relations between different
amplitudes.Comment: 6 pages, contribution to the poster section of QCD@Work 2012
--International Workshop on QCD: Theory and Experiment--, 18-21 June 2012,
Lecce (Italy
Thermal power terms in the Einstein-dilaton system
We employ the gauge/string duality to study the thermal power terms of
various thermodynamic quantities in gauge theories and the renormalized
Polyakov loop above the deconfinement phase transition. We restrict ourselves
to the five-dimensional Einstein gravity coupled to a single scalar, the
dilaton. The asymptotic solutions of the system for a general dilaton potential
are employed to study the power contributions of various quantities. If the
dilaton is dual to the dimension-4 operator , no power
corrections would be generated. Then the thermal quantities approach their
asymptotic values much more quickly than those observed in lattice simulation.
When the dimension of the dual operator is different from 4, various power
terms are generated. The lowest power contributions to the thermal quantities
are always quadratic in the dilaton, while that of the Polyakov loop is linear.
As a result, the quadratic terms in inverse temperature for both the trace
anomaly and the Polyakov loop, observed in lattice simulation, cannot be
implemented consistently in the system. This is in accordance with the field
theory expectation, where no gauge-invariant operator can accommodate such
contributions. Two simple models, where the dilaton is dual to operators with
different dimensions, are studied in detail to clarify the conclusion.Comment: 25 pages, 5 figure
Holography, chiral Lagrangian and form factor relations
We perform a detailed study of mesonic properties in a class of holographic
models of QCD, which is described by the Yang-Mills plus Chern-Simons action.
By decomposing the 5 dimensional gauge field into resonances and integrating
out the massive ones, we reproduce the Chiral Perturbative Theory Lagrangian up
to and obtain all the relevant low energy constants (LECs). The
numerical predictions of the LECs show minor model dependence, and agree
reasonably with the determinations from other approaches. Interestingly,
various model-independent relations appear among them. Some of these relations
are found to be the large-distance limits of universal relations between form
factors of the anomalous and even-parity sectors of QCD.Comment: Typo corrected; 8 pages, 1 figure; Proceedings of the Xth Quark
Confinement and the Hadron Spectrum, October 8-12, 2012, TUM Campus Garching,
Munich, German
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