254 research outputs found
Moduli trapping mechanism in modular flavor symmetric models
We discuss how the moduli in modular flavor symmetric models dynamically
select enhanced symmetry points at which the residual modular symmetry renders
extra matter fields massless. The moduli dynamics non-perturbatively produces
the extra matter particles, which gives (time-dependent) effective potential
that traps the moduli to enhanced symmetry points. We show analytic estimates
of particle production rate consistent with numerical results, and the dynamics
of moduli based on the analytic estimates.Comment: 35 pages, 14 figure
Dynamics of Superconformal Axion: Quality and Scalegenesis
We explore a dynamical mechanism to realize the emergence of a global
symmetry and its spontaneous breaking at an intermediate scale
for an axion solution to the strong CP problem. Such a dynamics is provided by
a new supersymmetric QCD near the middle of conformal window that couples to
fields spontaneously breaking the symmetry. A large anomalous
dimension of the breaking fields leads to the suppression of
explicit -violating higher dimensional operators. The breaking vacuum is generated at a scale hierarchically smaller than the
Planck scale by a non-perturbative effect. The breaking drives
the conformal breaking, and all the new quarks become massive. The axion
potential is generated by the ordinary color effect as the symmetry is only anomalous under the . The saxion direction is
stabilized by supersymmetry breaking and cosmologically harmless.Comment: 8 pages, 3 figure
Dynamically emergent gravity from hidden local Lorentz symmetry
Gravity can be regarded as a consequence of local Lorentz (LL) symmetry,
which is essential in defining a spinor field in curved spacetime. The
gravitational action may admit a zero-field limit of the metric and vierbein at
a certain ultraviolet cutoff scale such that the action becomes a linear
realization of the LL symmetry. Consequently, only three types of term are
allowed in the four-dimensional gravitational action at the cutoff scale: a
cosmological constant, a linear term of the LL field strength, and spinor
kinetic terms, whose coefficients are in general arbitrary functions of LL and
diffeomorphism invariants. In particular, all the kinetic terms are prohibited
except for spinor fields, and hence the other fields are auxiliary. Their
kinetic terms, including those of the LL gauge field and the vierbein, are
induced by spinor loops simultaneously with the LL gauge field mass. The LL
symmetry is necessarily broken spontaneously and hence is nothing but a hidden
local symmetry, from which gravity is emergent.Comment: 7 pages; version accepted for publication in Phys. Lett. B; a table,
footnotes, references, and comments adde
Note on Constructing Constrained PRFs from OWFs with Constant Collusion Resistance
Constrained pseudorandom functions (CPRFs) are a type of PRFs that allows one to derive a constrained key from the master key . While the master key allows one to evaluate on any input as a standard PRF, the constrained key only allows one to evaluate on inputs such that .
Since the introduction of CPRFs by Boneh and Waters (ASIACRYPT\u2713), Kiayias et al. (CCS\u2713), and Boyle et al. (PKC\u2714), there have been various constructions of CPRFs.
However, thus far, almost all constructions (from standard assumptions and non-trivial constraints) are only proven to be secure if at most one constrained key is known to the adversary, excluding the very recent work of Davidson and Nishimaki (EPRINT\u2718).
Considering the interesting applications of CPRFs such as ID-based non-interactive key exchange, we desire CPRFs that are collusion resistance with respect to the constrained keys.
In this work, we make progress in this direction and construct a CPRF for the bit-fixing predicates that are collusion resistance for a constant number of constrained keys.
Surprisingly, compared to the heavy machinery that was used by previous CPRF constructions, our construction only relies on the existence of one-way functions
Dissipation of axion energy via the Schwinger and Witten effects
In the presence of an anomalous CP phase in a U(1) gauge theory, a monopole
becomes a dyon via the Witten effect. When the anomalous CP phase is promoted
to a dynamical field, the axion, the electric charge of the dyon changes
according to the coherent motion of the axion oscillation. Once the electric
charge exceeds a certain threshold, the Schwinger pair production of charged
particles becomes efficient near the surface of the dyon. These
non-perturbative effects lead to the back reaction of the axion dynamics by
causing the dissipation of the axion oscillation energy and the change of the
effective potential due to the Witten effect. Taking these effects into
account, we consider the dynamics of the whole system, including the axion,
monopole, and charged heavy vector bosons, and discuss to what extent the axion
abundance is modified. We also discuss the electric dipole radiation from a
bound state of a monopole-anti-monopole pair due to the axion coherent
oscillations.Comment: 22 pages, 9 figure
Biosynthesis of unnatural glycolipids possessing diyne moiety in the acyl chain in the green sulfur photosynthetic bacterium Chlorobaculum tepidum grown by supplementation of 10,12-heptadecadiynic acid
AbstractUnnatural glycolipids possessing the diyne moiety in their acyl groups were successfully biosynthesized in the green sulfur photosynthetic bacterium Chlorobaculum (Cba.) tepidum by cultivation with supplementation of 10,12-heptadecadiynic acid. Monogalactosyldiacylglycerol (MGDG) and rhamnosylgalactosyldiacylglycerol (RGDG) esterified with one 10,12-heptadecadiynic acid were primarily formed in the cells, and small amounts of glycolipids esterified with the two unnatural fatty acids can also be detected. The relative ratio of these unnatural glycolipids occupied in the total glycolipids was estimated to be 49% based on HPLC analysis using a evaporative light scattering detector. These results indicate that the acyl groups in glycolipids, which play important roles in the formation of extramembranous antenna complexes called chlorosomes, can be modified in vivo by cultivation of green sulfur photosynthetic bacteria with exogenous synthetic fatty acids. Visible absorption and circular dichroism spectra of Cba. tepidum containing the unnatural glycolipids demonstrated the formation of chlorosomes, indicating that the unnatural glycolipids in this study did not interfere with the biogenesis of chlorosomes
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