6,620 research outputs found
Refined topological amplitudes in N=1 flux compactification
We study the implication of refined topological string amplitudes in the
supersymmetric N=1 flux compactification. They generate higher derivative
couplings among the vector multiplets and graviphoton with generically
non-holomorphic moduli dependence. For a particular term, we can compute them
by assuming the geometric engineering. We claim that the Dijkgraaf-Vafa large N
matrix model with the beta-ensemble measure directly computes the higher
derivative corrections to the supersymmetric effective action of the
supersymmetric N=1$ gauge theory.Comment: 16 pages, v2: reference adde
General Analysis of Inflation in the Jordan frame Supergravity
We study various inflation models in the Jordan frame supergravity with a
logarithmic Kahler potential. We find that, in a class of inflation models
containing an additional singlet in the superpotential, three types of
inflation can be realized: the Higgs-type inflation, power-law inflation, and
chaotic inflation with/without a running kinetic term. The former two are
possible if the holomorphic function dominates over the non-holomorphic one in
the frame function, while the chaotic inflation occurs when both are
comparable. Interestingly, the fractional-power potential can be realized by
the running kinetic term. We also discuss the implication for the Higgs
inflation in supergravity.Comment: 16 pages, 1 figur
Non-trivial Center Dominance in High Temperature QCD
We investigate the properties of quarks and gluons above the chiral phase
transition temperature using the RG improved gauge action and the Wilson
quark action with two degenerate quarks mainly on a lattice. In
the one-loop perturbation theory, the thermal ensemble is dominated by the
gauge configurations with effectively center twisted boundary
conditions, making the thermal expectation value of the spatial Polyakov loop
take a non-trivial center. This is in agreement with our lattice
simulation of high temperature QCD. We further observe that the temporal
propagator of massless quarks at extremely high temperature remarkably agrees with the temporal propagator of free
quarks with the twisted boundary condition for , but
differs from that with the trivial boundary condition. As we increase
the mass of quarks , we find that the thermal ensemble continues to be
dominated by the twisted gauge field configurations as long as and above that the trivial configurations come in. The
transition is essentially identical to what we found in the departure from the
conformal region in the zero-temperature many-flavor conformal QCD on a finite
lattice by increasing the mass of quarks. We argue that the behavior is
consistent with the renormalization group analysis at finite temperature.Comment: 16 pages, 9 figures; 4 tables, an appendix adde
IR fixed points in gauge Theories
We propose a novel RG method to specify the location of the IR fixed point in
lattice gauge theories and apply it to the gauge theories with
fundamental fermions. It is based on the scaling behavior of the propagator
through the RG analysis with a finite IR cut-off, which we cannot remove in the
conformal field theories in sharp contrast with the confining theories. The
method also enables us to estimate the anomalous mass dimension in the
continuum limit at the IR fixed point. We perform the program for and and indeed identify the location of the IR fixed points in all
cases.Comment: 7 pages, 7 figures, 1 table: the scale of the y axis in Figs..1-4
change; minor modifications as appear in PL
Higgs Chaotic Inflation in Standard Model and NMSSM
We construct a chaotic inflation model in which the Higgs fields play the
role of the inflaton in the standard model as well as in the singlet extension
of the supersymmetric standard model. The key idea is to allow a non-canonical
kinetic term for the Higgs field. The model is a realization of the recently
proposed running kinetic inflation, in which the coefficient of the kinetic
term grows as the inflaton field. The inflaton potential depends on the
structure of the Higgs kinetic term. For instance, the inflaton potential is
proportional to phi^2 and phi^{2/3} in the standard model and NMSSM,
respectively. It is also possible to have a flatter inflaton potential.Comment: 5 pages. v2:discussion and references adde
Impaired germ cell development due to compromised cell cycle progression in Skp2-deficient mice
BACKGROUND: The gonads are responsible for the production of germ cells through both mitosis and meiosis. Skp2 is the receptor subunit of an SCF-type ubiquitin ligase and is a major regulator of the progression of cells into S phase of the cell cycle, which it promotes by mediating the ubiquitin-dependent degradation of p27, an inhibitor of cell proliferation. However, the role of the Skp2-p27 pathway in germ cell development remains elusive. RESULTS: We now show that disruption of Skp2 in mice results in a marked impairment in the fertility of males, with the phenotypes resembling Sertoli cell-only syndrome in men. Testes of Skp2(-/- )mice manifested pronounced germ cell hypoplasia accompanied by massive apoptosis in spermatogenic cells. Flow cytometry revealed an increased prevalence of polyploidy in spermatozoa, suggesting that the aneuploidy of these cells is responsible for the induction of apoptosis. Disruption of the p27 gene of Skp2(-/- )mice restored germ cell development, indicating that the testicular hypoplasia of Skp2(-/- )animals is attributable to the antiproliferative effect of p27 accumulation. CONCLUSION: Our results thus suggest that compromised cell cycle progression caused by the accumulation of p27 results in aneuploidy and the induction of apoptosis in gonadal cells of Skp2(-/- )mice. The consequent reduction in the number of mature gametes accounts for the decreased fertility of these animals. These findings reinforce the importance of the Skp2-p27 pathway in cell cycle regulation and in germ cell development
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