2,388 research outputs found
Consequences of Fine-Tuning for Fifth Force Searches
Light bosonic fields mediate long range forces between objects. If these
fields have self-interactions, i.e., non-quadratic terms in the potential, the
experimental constraints on such forces can be drastically altered due to a
screening (chameleon) or enhancement effect. We explore how technically natural
values for such self-interaction coupling constants modify the existing
constraints. We point out that assuming the existence of these natural
interactions leads to new constraints, contrary to the usual expectation that
screening leads to gaps in coverage. We discuss how screening can turn
fundamentally equivalence principle (EP)-preserving forces into EP-violating
ones. This means that when natural screening is present, searches for EP
violation can be used to constrain EP-preserving forces. We show how this
effect enables the recently discovered stellar triple system \textit{PSR
J03371715} to place a powerful constraint on EP-preserving fifth forces.
Finally, we demonstrate that technically natural cubic self-interactions modify
the vacuum structure of the scalar potential, leading to new constraints from
spontaneous and induced vacuum decay.Comment: 36 pages, 9 figures -- v3 reflects version published in JHE
Superpartners at LHC and Future Colliders: Predictions from Constrained Compactified M-Theory
We study a realistic top-down M-theory compactification with low-scale
effective Supersymmetry, consistent with phenomenological constraints. A
combination of top-down and generic phenomenological constraints fix the
spectrum. The gluino mass is predicted to be about 1.5 TeV. Three and only
three superpartner channels, , and
(where are Wino-like), are expected
to be observable at LHC-14. We also investigate the prospects of finding heavy
squarks and Higgsinos at future colliders. Gluino-stop-top,
gluino-sbottom-bottom associated production and first generation squark
associated production should be observable at a 100 TeV collider, along with
direct production of heavy Higgsinos. Within this framework the discovery of a
single sparticle is sufficient to determine uniquely the SUSY spectrum,
yielding a number of concrete testable predictions for LHC-14 and future
colliders, and determination of and thereby other fundamental
quantities.Comment: 19 pages, 4 figure
Mixed Heavy-Light Matching in the Universal One-Loop Effective Action
Recently, a general result for evaluating the path integral at one loop was
obtained in the form of the Universal One-Loop Effective Action. It may be used
to derive effective field theory operators of dimensions up to six, by
evaluating the traces of matrices in this expression, with the mass-dependence
encapsulated in the universal coefficients. Here we show that it can account
for loops of mixed heavy-light particles in the matching procedure. Our
prescription for computing these mixed contributions to the Wilson coefficients
is conceptually simple. Moreover it has the advantage of maintaining the
universal structure of the effective action, which we illustrate using the
example of integrating out a heavy electroweak triplet scalar coupling to a
light Higgs doublet. Finally we also identify new structures that were
previously neglected in the universal results.Comment: 22 pages, 3 figures; v2: expanded discussion in Section 3, typos
correcte
Extending the Universal One-Loop Effective Action: Heavy-Light Coefficients
The Universal One-Loop Effective Action (UOLEA) is a general expression for
the effective action obtained by evaluating in a model-independent way the
one-loop expansion of a functional path integral. It can be used to match UV
theories to their low-energy EFTs more efficiently by avoiding redundant steps
in the application of functional methods, simplifying the process of obtaining
Wilson coefficients of operators up to dimension six. In addition to loops
involving only heavy fields, matching may require the inclusion of loops
containing both heavy and light particles. Here we use the recently-developed
covariant diagram technique to extend the UOLEA to include heavy-light terms
which retain the same universal structure as the previously-derived heavy-only
terms. As an example of its application, we integrate out a heavy singlet
scalar with a linear coupling to a light doublet Higgs. The extension presented
here is a first step towards completing the UOLEA to incorporate all possible
structures encountered in a covariant derivative expansion of the one-loop path
integral.Comment: 20 pages, 1 figure, 5 tables, 1 Mathematica Noteboo
Survey of vector-like fermion extensions of the Standard Model and their phenomenological implications
With the renewed interest in vector-like fermion extensions of the Standard
Model, we present here a study of multiple vector-like theories and their
phenomenological implications. Our focus is mostly on minimal flavor conserving
theories that couple the vector-like fermions to the SM gauge fields and mix
only weakly with SM fermions so as to avoid flavor problems. We present
calculations for precision electroweak and vector-like state decays, which are
needed to investigate compatibility with currently known data. We investigate
the impact of vector-like fermions on Higgs boson production and decay,
including loop contributions, in a wide variety of vector-like extensions and
their parameter spaces.Comment: 43 pages, 17 figures; v2: text modified to improve readability,
references added, journal versio
- …