45,264 research outputs found
Direct and Indirect Couplings in Coherent Feedback Control of Linear Quantum Systems
The purpose of this paper is to study and design direct and indirect
couplings for use in coherent feedback control of a class of linear quantum
stochastic systems. A general physical model for a nominal linear quantum
system coupled directly and indirectly to external systems is presented.
Fundamental properties of stability, dissipation, passivity, and gain for this
class of linear quantum models are presented and characterized using complex
Lyapunov equations and linear matrix inequalities (LMIs). Coherent
and LQG synthesis methods are extended to accommodate direct couplings using
multistep optimization. Examples are given to illustrate the results.Comment: 33 pages, 7 figures; accepted for publication in IEEE Transactions on
Automatic Control, October 201
Effective field theory approach to trans-TeV supersymmetry: covariant matching, Yukawa unification and Higgs couplings
Dismissing traditional naturalness concerns while embracing the Higgs boson
mass measurement and unification motivates careful analysis of trans-TeV
supersymmetric theories. We take an effective field theory (EFT) approach,
matching the Minimal Supersymmetric Standard Model (MSSM) onto the Standard
Model (SM) EFT by integrating out heavy superpartners, and evolving MSSM and
SMEFT parameters according to renormalization group equations in each regime.
Our matching calculation is facilitated by the recent covariant diagrams
formulation of functional matching techniques, with the full one-loop SUSY
threshold corrections encoded in just 30 diagrams. Requiring consistent
matching onto the SMEFT with its parameters (those in the Higgs potential in
particular) measured at low energies, and in addition requiring unification of
bottom and tau Yukawa couplings at the scale of gauge coupling unification, we
detail the solution space of superpartner masses from the TeV scale to well
above. We also provide detailed views of parameter space where Higgs coupling
measurements have probing capability at future colliders beyond the reach of
direct superpartner searches at the LHC.Comment: 59 pages, 8 figures; v2: references and minor clarifications adde
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