186 research outputs found
Natural Supersymmetry in Warped Space
We explore the possibility of solving the hierarchy problem by combining the
paradigms of supersymmetry and compositeness. Both paradigms are under pressure
from the results of the Large Hadron Collider (LHC), and combining them allows
both a higher confinement scale -- due to effective supersymmetry in the low
energy theory -- and heavier superpartners -- due to the composite nature of
the Higgs boson -- without sacrificing naturalness. The supersymmetric
Randall-Sundrum model provides a concrete example where calculations are
possible, and we pursue a realistic model in this context. With a few
assumptions, we are led to a model with bulk fermions, a left-right gauge
symmetry in the bulk, and supersymmetry breaking on the UV brane. The first two
generations of squarks are decoupled, reducing LHC signatures but also leading
to quadratic divergences at two loops. The model predicts light and
gauge bosons, and present LHC constraints on exotic gauge bosons imply a high
confinement scale and mild tuning from the quadratic divergences, but the model
is otherwise viable. We also point out that R-parity violation can arise
naturally in this context.Comment: 60 pages, 7 figures; v2: minor changes, references added, published
versio
Evidence for a Lattice Weak Gravity Conjecture
The Weak Gravity Conjecture postulates the existence of superextremal charged
particles, i.e. those with mass smaller than or equal to their charge in Planck
units. We present further evidence for our recent observation that in known
examples a much stronger statement is true: an infinite tower of superextremal
particles of different charges exists. We show that effective Kaluza-Klein
field theories and perturbative string vacua respect the Sublattice Weak
Gravity Conjecture, namely that a finite index sublattice of the full charge
lattice exists with a superextremal particle at each site. In perturbative
string theory we show that this follows from modular invariance. However, we
present counterexamples to the stronger possibility that a superextremal
particle exists at every lattice site, including an example in which the
lightest charged particle is subextremal. The Sublattice Weak Gravity
Conjecture has many implications both for abstract theories of quantum gravity
and for real-world physics. For instance, it implies that if a gauge group with
very small coupling exists, then the fundamental gravitational cutoff
energy of the theory is no higher than .Comment: v2: 41 pages, typos fixed, references added, substantial revisions
and clarifications (conclusions unchanged
The Weak Gravity Conjecture and Emergence from an Ultraviolet Cutoff
We study ultraviolet cutoffs associated with the Weak Gravity Conjecture
(WGC) and Sublattice Weak Gravity Conjecture (sLWGC). There is a magnetic WGC
cutoff at the energy scale with an associated sLWGC tower of
charged particles. A more fundamental cutoff is the scale at which gravity
becomes strong and field theory breaks down entirely. By clarifying the nature
of the sLWGC for nonabelian gauge groups we derive a parametric upper bound on
this strong gravity scale for arbitrary gauge theories. Intriguingly, we show
that in theories approximately saturating the sLWGC, the scales at which loop
corrections from the tower of charged particles to the gauge boson and graviton
propagators become important are parametrically identical. This suggests a
picture in which gauge fields emerge from the quantum gravity scale by
integrating out a tower of charged matter fields. We derive a converse
statement: if a gauge theory becomes strongly coupled at or below the quantum
gravity scale, the WGC follows. We sketch some phenomenological consequences of
the UV cutoffs we derive.Comment: 50 pages, 5 figures. v2: references added, clarified remarks about
Higgsin
New N=1 dualities from orientifold transitions - Part II: String Theory
We present a string theoretical description, given in terms of branes and
orientifolds wrapping vanishing cycles, of the dual pairs of gauge theories
analyzed in 1210.7799. Based on the resulting construction we argue that the
duality that we observe in field theory is inherited from S-duality of type IIB
string theory. We analyze in detail the complex cone over the zeroth del Pezzo
surface and discuss an infinite family of orbifolds of flat space. For the del
Pezzo case we describe the system in terms of large volume objects, and show
that in this language the duality can be understood from the strongly coupled
behavior of the O7^+ plane, which we analyze using simple F-theory
considerations. For all cases we also give a different argument based on the
existence of appropriate torsional components of the 3-form flux lattice. Along
the way we clarify some aspects of the description of orientifolds in the
derived category of coherent sheaves, and in particular we discuss the
important role played by exotic orientifolds - ordinary orientifolds composed
with auto-equivalences of the category - when describing orientifolds of
ordinary quiver gauge theories.Comment: 51 pages, 16 figures; v2: minor changes, added references, published
versio
Mesino Oscillation in MFV SUSY
R-parity violating supersymmetry in a Minimal Flavor Violation paradigm can
produce same-sign dilepton signals via direct sbottom-LSP pair production. Such
signals arise when the sbottom hadronizes and the resulting mesino oscillates
into an anti-mesino. The first bounds on the sbottom mass are placed in this
scenario using current LHC results.Comment: 14 pages, 6 figure
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