425 research outputs found
Chiral rings and GSO projection in Orbifolds
The GSO projection in the twisted sector of orbifold background is sometimes
subtle and incompatible descriptions are found in literatures. Here, from the
equivalence of partition functions in NSR and GS formalisms, we give a simple
rule of GSO projection for the chiral rings of string theory in \C^r/\Z_n,
. Necessary constructions of chiral rings are given by explicit mode
analysis.Comment: 24 page
Closed string tachyon potential and equation
Recently Dabholkar and Vafa proposed that closed string tachyon potential for
non-supersymmetric orbifold \C/\Z_3 in terms of the solution of a
equation. We extend this result to \C^2/\Z_n for . Interestingly,
the tachyon potentials for and 4 are still given in terms of the
solutions of Painleve III type equation that appeared in the study of
\C^1/\Z_3 with different boundary conditions. For \C^2/\Z_5 case, governing
equations are of generalized Toda type. The potential is monotonically
decreasing function of RG flow.Comment: 15 pages, reference added. to appear in PL
The effect of gluon condensate on holographic heavy quark potential
The gluon condensate is very sensitive to the QCD deconfinement transition
since its value changes drastically with the deconfinement transition. We
calculate the gluon condensate dependence of the heavy quark potential in
AdS/CFT to study how the property of the heavy quarkonium is affected by a
relic of the deconfinement transition. We observe that the heavy quark
potential becomes deeper as the value of the gluon condensate decreases. We
interpret this as a dropping of the heavy quarkonium mass just above the
deconfinement transition, which is similar to the results obtained from QCD sum
rule and from a bottom-up AdS/QCD model.Comment: 16 pages, 6 figures, typos corrected, references adde
Quark number Susceptibility and Phase Transition in hQCD Models
We study the quark number susceptibility, an indicator of QCD phase
transition, in the hard wall and soft wall models of hQCD. We find that the
susceptibilities in both models are the same, jumping up at the deconfinement
phase transition temperature. We also find that the diffusion constant in the
soft wall model is enhanced compared to the one in the hard wall model.Comment: 14 pages, 2 figure
Comments on the Fate of unstable orbifolds
We study the localized tachyon condensation in their mirror Landau-Ginzburg
picture. We completely determine the decay mode of an unstable orbifold
, under the condensation of a tachyon with definite R-charge
and mass by extending the Vafa's work hep-th/0111105. Here, we give a simple
method that works uniformly for all . For , where method of
toric geometry works, we give a proof of equivalence of our method with toric
one. For cases, the orbifolds decay into sum of far separated
orbifolds.Comment: 14 page, 2 figure
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