Resource
2015 EN
Andrew J. Larkoski · Fabio Maltoni · Michele Selvaggi
The identification of hadronically decaying heavy states, such as vectorbosons, the Higgs, or the top quark, produced with large transverse boosts hasbeen and will continue to be a central focus of the jet physics program at theLarge Hadron Collider (LHC). At a future hadron collider working at anorder-of-magnitude larger energy than the LHC, these heavy states would beeasily produced with transverse boosts of several TeV. At these energies, theirdecay products will be separated by angular scales comparable to individualcalorimeter cells, making the current jet substructure identificationtechniques for hadronic decay modes not directly employable. In addition, atthe high energy and luminosity projected at a future hadron collider, therewill be numerous sources for contamination including initial- and final-stateradiation, underlying event, or pile-up which must be mitigated. We propose asimple strategy to tag such "hyper-boosted" objects that defines jets withradii that scale inversely proportional to their transverse boost and combinesthe standard calorimetric information with charged track-based observables. Bymeans of a fast detector simulation, we apply it to top quark identificationand demonstrate that our method efficiently discriminates hadronically decayingtop quarks from light QCD jets up to transverse boosts of 20 TeV. Our resultsopen the way to tagging heavy objects with energies in the multi-TeV range atpresent and future hadron colliders.
Resource
2015 EN
Daniela Bubboloni · Michele Gori
In the standard arrovian framework and under the assumption that individualpreferences and social outcomes are linear orders on the set of alternatives,we study the rules which satisfy suitable symmetries and obey the majorityprinciple. In particular, supposing that individuals and alternatives areexogenously partitioned into subcommittees and subclasses, we provide necessaryand sufficient conditions for the existence of reversal symmetric majorityrules that are anonymous and neutral with respect to the considered partitions.We also determine a general method for constructing and counting those rulesand we explicitly apply it to some simple cases.
Resource
2015 EN
Sean Bryan · Kristi Bradford · George Che
+10 more
Mapping the polarization of the Cosmic Microwave Background is yieldingexciting data on the origin of the universe, the reionization of the universe,and the growth of cosmic structure. Kilopixel arrays represent the currentstate of the art, but advances in detector technology are needed to enable thelarger detector arrays needed for future measurements. Here we present a designfor single-band dual-polarization Kinetic Inductance Detectors (KIDs) at 20%bandwidths centered at 145, 220, and 280 GHz. The detection and readout systemis nearly identical to the successful photon-noise-limited aluminumLumped-Element KIDs that have been recently built and tested by some of theauthors. Fabricating large focal plane arrays of the feed horns andquarter-wave backshorts requires only conventional precision machining. Sincethe detectors and readout lines consist only of a single patterned aluminumlayer on a SOI wafer, arrays of the detectors can be built commercially or at astandard university cleanroom.
Resource
2015 EN
Yongxin Chen · Tryphon Georgiou · Michele Pavon
We consider a variant of the classical linear quadratic Gaussian regulator(LQG) in which penalties on the endpoint state are replaced by thespecification of the terminal state distribution. The resulting theoryconsiderably differs from LQG as well as from formulations that bound theprobability of violating state constraints. We develop results for optimalstate-feedback control in the two cases where i) steering of the statedistribution is to take place over a finite window of time with minimum energy,and ii) the goal is to maintain the state at a stationary distribution over aninfinite horizon with minimum power. For both problems the distribution ofnoise and state are Gaussian. In the first case, we show that provided thesystem is controllable, the state can be steered to any terminal Gaussiandistribution over any specified finite time-interval. In the second case, wecharacterize explicitly the covariance of admissible stationary statedistributions that can be maintained with constant state-feedback control. Theconditions for optimality are expressed in terms of a system of dynamicallycoupled Riccati equations in the finite horizon case and in terms of algebraicconditions for the stationary case. In the case where the noise and controlshare identical input channels, the Riccati equations for finite-horizonsteering become homogeneous and can be solved in closed form. The present paperis largely based on our recent work in arxiv.org/abs/1408.2222,arxiv.org/abs/1410.3447 and presents an overview of certain key results.
Resource
2015 EN
Simona Settepanella · Michele Torielli
In this paper we give a very natural description of the bijections betweenthe minimal CW-complex homotopy equivalent to the complement of a supersolvablearrangement $\mathcal{A}$, the $\textbf{nbc}$ basis of the Orlik-Solomonalgebra associated to $\mathcal{A}$ and the set of chambers of $\mathcal{A}$.We use these bijections to get results on the first (co)homology group of theMilnor fiber of $\mathcal{A}$ and to describe a bijection between the symmetricgroup and the $\textbf{nbc}$ basis of the braid arrangement.
Resource
2015 EN
Michele Tucci · Stefano Riverso · Juan C. Vasquez
+2 more
We propose a new decentralized control scheme for DC Islanded microGrids(ImGs) composed by several Distributed Generation Units (DGUs) with a generalinterconnection topology. Each local controller regulates to a reference valuethe voltage of the Point of Common Coupling (PCC) of the corresponding DGU.Notably, off-line control design is conducted in a Plug-and-Play (PnP) fashionmeaning that (i) the possibility of adding/removing a DGU without spoilingstability of the overall ImG is checked through an optimization problem; (ii)when a DGU is plugged in or out at most neighbouring DGUs have to update theircontrollers and (iii) the synthesis of a local controller uses only informationon the corresponding DGU and lines connected to it. This guarantee totalscalability of control synthesis as the ImG size grows or DGU gets replaced.Yes, under mild approximations of line dynamics, we formally guaranteestability of the overall closed-loop ImG. The performance of the proposedcontrollers is analyzed simulating different scenarios in PSCAD.
Resource
2015 EN
Michele Bonnin
A description in terms of phase and amplitude variables is given, fornonlinear oscillators subject to white Gaussian noise described by It\^ostochastic differential equations. The stochastic differential equationsderived for the amplitude and the phase are rigorous, and their validity is notlimited to the weak noise limit. If the noise intensity is small, the equationscan be efficiently solved using asymptotic expansions. Formulas for theexpected angular frequency, expected oscillation amplitude and amplitudevariance are derived using It\^o calculus.
Resource
2015 EN
Sergio Cecotti · Michele Del Zotto
The BPS spectrum of many 4d N=2 theories may be seen as the (categorical)Galois cover of the BPS spectrum of a different 4d N=2 model. The Galois groupG acts as a physical symmetry of the covering N=2 model. The simplest instanceis SU(2) SQCD with N_f=2 quarks, whose BPS spectrum is a Z_2-cover of the BPSspectrum of pure SYM. More generally, N=2 SYM with simply--laced gauge groupadmits Z_k-covers for all k; e.g. the Z_2-cover of SO(8) SYM is SO(8) SYMcoupled to two copies of the E_6 Minahan-Nemeshanski SCFT. Galois coverssimplify considerably the computation of the BPS spectrum at G-symmetricpoints, in both finite and infinite chambers. When the covering and quotientQFTs admit a geometric engineering, say for class S models, the categoricalspectral cover may be realized as a covering map in the geometry. Aparticularly nice instance is when the spectral Galois cover is induced by amodular cover of principal modular curves, X(NM)-> X(M), or, more generally, byregular Grothendieck's dessins d'enfants; the BPS spectra of the correspondingN=2 QFTs have magic properties. The Galois covers allow to study effectivelythe action of the quantum (half)monodromy of 4d N=2 QFTs. We present severalexamples and applications of the spectral covering philosophy.
Resource
2015 EN
Oleg Antipin · Michele Redi · Alessandro Strumia
+1 more
We build models where Dark Matter candidates arise as composite states of anew confining gauge force, stable thanks to accidental symmetries. Restrictingto renormalizable theories compatible with SU(5) unification, we find 13 modelsbased on SU(N) gauge theories and 9 based on SO(N). We also describe othermodels that require non-renormalizable interactions. The two gauge groups leadto distinctive phenomenologies: SU(N) theories give complex DM, withpotentially observable electric and magnetic dipole moments that lead topeculiar spin-independent cross sections; SO(N) theories give real DM, withchallenging spin-dependent cross sections or inelastic scatterings. Models withYukawa couplings also give rise to spin-independent direct detection mediatedby the Higgs boson and to electric dipole moments for the electron. In somemodels DM has higher spin. Each model predicts a specific set of lightercomposite scalars, possibly observable at colliders.
Resource
2015 EN
Yongxin Chen · Tryphon T. Georgiou · Michele Pavon
Consider a linear stochastic system whose initial state is a random vectorwith a specified Gaussian distribution. Such a distribution may represent acollection of particles abiding by the specified system dynamics. In recentpublications, we have shown that, provided the system is controllable, it isalways possible to steer the state covariance to any specified terminalGaussian distribution using state feedback. The purpose of the present work isto show that, in the case where only partial state observation is available, anecessary and sufficient condition for being able to steer the system to aspecified terminal Gaussian distribution for the state vector is that theterminal state covariance be greater (in the positive-definite sense) than theerror covariance of a corresponding Kalman filter.