1,492 research outputs found
Unifying CP violations of quark and lepton sectors
A preliminary determination of the Dirac phase in the PMNS matrix is
\dell\approx -\frac{\pi}{2}. A rather accurately determined Jarlskog
invariant in the CKM matrix is close to the maximum. Since the phases in
the CKM and PMNS matrices will be accurately determined in the future, it is an
interesting problem to relate these two phases. This can be achieved in a
families-unified grand unification if the weak CP violation is introduced
spontaneously {\it \`a la} Froggatt and Nielsen at a high energy scale, where
only one meaningful Dirac CP phase appears.Comment: 10 pages with 3 figure
Twist Deformations of the Supersymmetric Quantum Mechanics
The N-extended Supersymmetric Quantum Mechanics is deformed via an abelian
twist which preserves the super-Hopf algebra structure of its Universal
Enveloping Superalgebra. Two constructions are possible. For even N one can
identify the 1D N-extended superalgebra with the fermionic Heisenberg algebra.
Alternatively, supersymmetry generators can be realized as operators belonging
to the Universal Enveloping Superalgebra of one bosonic and several fermionic
oscillators. The deformed system is described in terms of twisted operators
satisfying twist-deformed (anti)commutators. The main differences between an
abelian twist defined in terms of fermionic operators and an abelian twist
defined in terms of bosonic operators are discussed.Comment: 18 pages; two references adde
D-brane Instantons as Gauge Instantons in Orientifolds of Chiral Quiver Theories
Systems of D3-branes at orientifold singularities can receive
non-perturbative D-brane instanton corrections, inducing field theory operators
in the 4d effective theory. In certain non-chiral examples, these systems have
been realized as the infrared endpoint of a Seiberg duality cascade, in which
the D-brane instanton effects arise from strong gauge theory dynamics. We
present the first UV duality cascade completion of chiral D3-brane theories, in
which the D-brane instantons arise from gauge theory dynamics. Chiral examples
are interesting because the instanton fermion zero mode sector is topologically
protected, and therefore lead to more robust setups. As an application of our
results, we provide a UV completion of certain D-brane orientifold systems
recently claimed to produce conformal field theories with conformal invariance
broken only by D-brane instantons.Comment: 50 pages, 32 figures. v2: version published in JHEP with references
adde
The Maximal Inverse Seesaw from Operator and Oscillating Asymmetric Sneutrino Dark Matter
The maximal supersymmetric inverse seesaw mechanism (MSIS)
provides a natural way to relate asymmetric dark matter (ADM) with neutrino
physics. In this paper we point out that, MSIS is a natural outcome if one
dynamically realizes the inverse seesaw mechanism in the next-to minimal
supersymmetric standard model (NMSSM) via the dimension-five operator
, with the NMSSM singlet developing TeV scale VEV; it
slightly violates lepton number due to the suppression by the fundamental scale
, thus preserving maximally. The resulting sneutrino is a
distinguishable ADM candidate, oscillating and favored to have weak scale mass.
A fairly large annihilating cross section of such a heavy ADM is available due
to the presence of singlet.Comment: journal versio
The Conformal Sector of F-theory GUTs
D3-brane probes of exceptional Yukawa points in F-theory GUTs are natural
hidden sectors for particle phenomenology. We find that coupling the probe to
the MSSM yields a new class of N = 1 conformal fixed points with computable
infrared R-charges. Quite surprisingly, we find that the MSSM only weakly mixes
with the strongly coupled sector in the sense that the MSSM fields pick up
small exactly computable anomalous dimensions. Additionally, we find that
although the states of the probe sector transform as complete GUT multiplets,
their coupling to Standard Model fields leads to a calculable threshold
correction to the running of the visible sector gauge couplings which improves
precision unification. We also briefly consider scenarios in which SUSY is
broken in the hidden sector. This leads to a gauge mediated spectrum for the
gauginos and first two superpartner generations, with additional contributions
to the third generation superpartners and Higgs sector.Comment: v2: 51 pages, 2 figures, remark added, typos correcte
Polarization and magnetization dynamics of a field-driven multiferroic structure
We consider a multiferroic chain with a linear magnetoelectric coupling
induced by the electrostatic screening at the ferroelectric/ferromagnet
interface. We study theoretically the dynamic ferroelectric and magnetic
response to external magnetic and electric fields by utilizing an approach
based on coupled Landau- Khalatnikov and finite-temperature
Landau-Lifshitz-Gilbert equations. Additionally, we compare with Monte Carlo
calculations. It is demonstrated that for material parameters corresponding to
BaTiO3/Fe the polarization and the magnetization are controllable by external
magnetic and electric fields respectively
The anomalous U(1) global symmetry and flavors from an SU(5) x SU(5) GUT in orbifold compactification
In string compactifications, frequently there appears the anomalous U(1)
gauge symmetry which belonged to E8E8 of the heterotic string. This
anomalous U(1) gauge boson obtains mass at the compactification scale, just
below GeV, by absorbing one pseudoscalar (corresponding to the
model-independent axion) from the second rank anti-symmetric tensor field
.
Below the compactification scale, there results a global symmetry U(1) whose charge is the original gauge U(1) charge. This is
the most natural global symmetry, realizing the "invisible" axion. This global
symmetry U(1) is suitable for a flavor symmetry. In the simplest
compactification model with the flipped SU(5) grand unification, we calculate
all the low energy parameters in terms of the vacuum expectation values of the
standard model singlets.Comment: 18 pages, 4 figur
Intra-strain elicitation and suppression of plant immunity by Ralstonia solanacearum type-III effectors in Nicotiana benthamiana
Effector proteins delivered inside plant cells are powerful weapons for bacterial pathogens, but this exposes the pathogen to potential recognition by the plant immune system. Therefore, the effector repertoire of a given pathogen must be balanced for a successful infection. Ralstonia solanacearum is an aggressive pathogen with a large repertoire of secreted effectors. One of these effectors, RipE1, is conserved in most R. solanacearum strains sequenced to date. In this work, we found that RipE1 triggers immunity in N. benthamiana, which requires the immune regulator SGT1, but not EDS1 or NRCs. Interestingly, RipE1-triggered immunity induces the accumulation of salicylic acid (SA) and the overexpression of several genes encoding phenylalanine-ammonia lyases (PALs), suggesting that the unconventional PAL-mediated pathway is responsible for the observed SA biosynthesis. Surprisingly, RipE1 recognition also induces the expression of jasmonic acid (JA)-responsive genes and JA biosynthesis, suggesting that both SA and JA may act cooperatively in response to RipE1. Finally, we found that RipE1 expression leads to the accumulation of glutathione in plant cells, which precedes the activation of immune responses. R. solanacearum secretes another effector, RipAY, which is known to inhibit immune responses by degrading cellular glutathione. Accordingly, we show that RipAY inhibits RipE1-triggered immune responses. This work shows a strategy employed by R. solanacearum to counteract the perception of its effector proteins by the plant immune system
String theoretic QCD axions in the light of PLANCK and BICEP2
The QCD axion solving the strong CP problem may originate from antisymmetric
tensor gauge fields in compactified string theory, with a decay constant around
the GUT scale. Such possibility appears to be ruled out now by the detection of
tensor modes by BICEP2 and the PLANCK constraints on isocurvature density
perturbations. A more interesting and still viable possibility is that the
string theoretic QCD axion is charged under an anomalous U(1)_A gauge symmetry.
In such case, the axion decay constant can be much lower than the GUT scale if
moduli are stabilized near the point of vanishing Fayet-Illiopoulos term, and
U(1)_A-charged matter fields get a vacuum value far below the GUT scale due to
a tachyonic SUSY breaking scalar mass. We examine the symmetry breaking pattern
of such models during the inflationary epoch with the Hubble expansion rate
10^{14} GeV, and identify the range of the QCD axion decay constant, as well as
the corresponding relic axion abundance, consistent with known cosmological
constraints. In addition to the case that the PQ symmetry is restored during
inflation, there are other viable scenarios, including that the PQ symmetry is
broken during inflation at high scales around 10^{16}-10^{17} GeV due to a
large Hubble-induced tachyonic scalar mass from the U(1)_A D-term, while the
present axion scale is in the range 10^{9}-5\times 10^{13} GeV, where the
present value larger than 10^{12} GeV requires a fine-tuning of the axion
misalignment angle. We also discuss the implications of our results for the
size of SUSY breaking soft masses.Comment: 29 pages, 1 figure; v3: analysis updated including the full
anharmonic effects, references added, version accepted for publication in
JHE
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