534 research outputs found
Little Higgs Model Completed with a Chiral Fermionic Sector
The implementation of the little Higgs mechanism to solve the hierarchy
problem provides an interesting guiding principle to build particle physics
models beyond the electroweak scale. Most model building works, however, pay
not much attention to the fermionic sector. Through a case example, we
illustrate how a complete and consistent fermionic sector of the TeV effective
field theory may actually be largely dictated by the gauge structure of the
model. The completed fermionic sector has specific flavor physics structure,
and many phenomenological constraints on the model can thus be obtained beyond
gauge, Higgs, and top physics. We take a first look on some of the quark sector
constraints.Comment: 14 revtex pages with no figure, largely a re-written version of
hep-ph/0307250 with elaboration on flavor sector FCNC constraints; accepted
for publication in Phys.Rev.
AN ATLAS FOR NAVIGATING THE INNOVATION ECOSYSTEM: HYBRID AIRSHIPS AS A USE CASE TO ENGAGE THE COMMERCIAL SECTOR
The Chief of Naval Operations and Commandant of the Marine Corps have stated the need to streamline innovation practices for faster adoption of emerging technologies to support force design initiatives. However, the Department of Defense (DOD) innovation ecosystem is difficult to navigate. This research develops an atlas to guide interaction and engagement for DOD personnel to navigate the innovation ecosystem while assessing commercially-developed, large-capacity transportation platforms. Using hybrid airships as the use case, the authors employed two research methods while developing the atlas: 1) technology progress and cost modeling and 2) market analysis through research and interviews with industry leaders. The results confirm that early DOD engagement with commercial partners can positively influence long-term procurement options. The authors believe that the atlas can guide timely and productive engagement with the commercial sector for the sustainable development of large-capacity platforms, but must have a framework that protects commercial intellectual property. We recommend that the DOD utilize the atlas to explore how commercial markets will affect future hybrid airship development, while creating a more complete picture of the function and utility of these versatile platforms.Outstanding ThesisCaptain, United States Marine CorpsCaptain, United States Marine CorpsApproved for public release. Distribution is unlimited
Understanding Pound-Drever-Hall locking using voltage controlled radio-frequency oscillators: An undergraduate experiment
We have developed a senior undergraduate experiment that illustrates
frequency stabilization techniques using radio-frequency electronics. The
primary objective is to frequency stabilize a voltage controlled oscillator to
a cavity resonance at 800 MHz using the Pound-Drever-Hall method. This
technique is commonly applied to stabilize lasers at optical frequencies. By
using only radio-frequency equipment it is possible to systematically study
aspects of the technique more thoroughly, inexpensively, and free from eye
hazards. Students also learn about modular radio-frequency electronics and
basic feedback control loops. By varying the temperature of the resonator,
students can determine the thermal expansion coefficients of copper, aluminum,
and super invar.Comment: 9 pages, 10 figure
One-loop flavor change in Little Higgs models
The Little Higgs (LH) idea attempts to cure the little amount of fine-tuning
necessary to bridge the gap between the Higgs mass (electroweak scale) and the
new physics scale suggested by electroweak precision tests (~10 TeV). However,
we show that LH models do not survive the confrontation with experimental
limits on lepton flavor mixing, assuming the same naturalness arguments that
motivate their introduction. Two different LH models are analyzed and several
aspects of their one-loop predictions for lepton flavor-changing processes are
discussed.Comment: 6 pages, 1 figure; contribution to Loops and Legs in Quantum Field
Theory, Woerlitz, Germany, April 25-30, 201
Report of the Subgroup on Alternative Models and New Ideas
We summarize some of the work done by the P3 subgroup on Alternative Models
and New Ideas. The working group covered a broad range of topics including a
constrained Standard Model from an extra dimension, a discussion of recent
ideas addressing the strong CP problem, searches for doubly charged higgs
bosons in e gamma collisions, and an update on discovery limits for extra
neutral gauge bosons at hadron colliders. The breadth of topics reflects the
many ideas and approaches to physics beyond the Standard Model.Comment: 10 pages, 5 figures. Contributed to the APS/DPF/DPB Summer Study on
the Future of Particle Physics (Snowmass 2001), Snowmass, Colorado, 30 Jun -
21 Jul 200
The Phase Structure of Supersymmetric Sp(2N_c) Gauge Theories with an Adjoint
We study the phase structure of N = 1 supersymmetric Sp(2N_c) gauge theories
with 2N_f fundamentals, an adjoint, and vanishing superpotential. Using
a-maximization, we derive analytic expressions for the values of N_f below
which the first several gauge-invariant operators in the chiral ring violate
the unitarity bound and become free fields. In doing so we are able to
explicitly check previous conjectures about the behavior of this theory made by
Luty, Schmaltz, and Terning. We then compare this to an analysis of the first
two 'deconfined' dual descriptions based on the gauge groups Sp(2N_f+2) x
SO(2N_c+5) and Sp(2N_f+2) x SO(4N_f+4) x Sp(2N_c+2), finding precise agreement.
In particular, we find no evidence for non-obvious accidental symmetries or the
appearance of a mixed phase in which one of the dual gauge groups becomes free.Comment: 18 pages, 2 figures; v2: added references to match JHEP versio
Vacuum Stability in Split Susy and Little Higgs Models
We study the stability of the effective higgs potential in the split
supersymmetry and Little Higgs models. In particular, we study the effects of
higher dimensional operators in the effective potential on the higgs mass
predictions. We find that the size and sign of the higher dimensional operators
can significantly change the higgs mass required to maintain vacuum stability
in Split Susy models. In the Little Higgs models the effects of higher
dimensional operators can be large because of a relatively lower cut-off scale.
Working with a specific model we find that a contribution from the higher
dimensional operator with coefficient of O(1) can destabilize the vacuum.Comment: Latex 22 pages, 3 figures. Added discussion, published versio
New Physics with earliest LHC data
We investigate which new physics models could be discovered in the first year of the LHC. Such a âSupermodelâ is a new physics scenario for which the LHC sensitivity with only 10 pbâ1 useful luminosity is greater than that of the
Tevatron with 10 fbâ1. The simplest supermodels involve s-channel resonances in the quark-antiquark and especially in the quark-quark channels. We concentrate on easily visible final states with small standard model backgrounds, and suggest simple searches, besides those for Z
states, which could discover new physics in
early LHC data
Bounds on SCFTs from Conformal Perturbation Theory
The operator product expansion (OPE) in 4d (super)conformal field theory is
of broad interest, for both formal and phenomenological applications. In this
paper, we use conformal perturbation theory to study the OPE of nearly-free
fields coupled to SCFTs. Under fairly general assumptions, we show that the OPE
of a chiral operator of dimension with its complex
conjugate always contains an operator of dimension less than . Our
bounds apply to Banks-Zaks fixed points and their generalizations, as we
illustrate using several examples.Comment: 36 pages; v2: typos fixed, minor change
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