Results for "Bogdan A. Dobrescu"

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Fermion Masses without Higgs: A Supersymmetric Technicolor ModelApr 26 1995Jun 05 1995We propose a supersymmetric technicolor model in which the electroweak symmetry breaking is communicated to the quarks and leptons by technicolored $SU(2)_W$-singlet scalars. When the technifermions condense, the quarks and leptons of the third generation ... More
Gluino mass from dynamical supersymmetry breakingOct 27 1995Jan 11 1996We present a new mechanism for gluino mass generation in models of dynamical supersymmetry breaking. The mechanism requires two colored chiral superfields which feel a nonabelian gauge interaction such that a fermion condensate is formed at a scale of ... More
Massless Gauge Bosons other than the PhotonNov 01 2004Gauge bosons associated with unbroken gauge symmetries, under which all standard model fields are singlets, may interact with ordinary matter via higher-dimensional operators. A complete set of dimension-six operators involving a massless U(1) field, ... More
B - L Mediated Supersymmetry BreakingMar 22 1997May 06 1997I present a realistic model of dynamical supersymmetry breaking, in which a $U(1)_{B-L}$ gauge interaction communicates supersymmetry breaking to the standard fields. A distinctive superpartner spectrum is predicted in this model.
The strong CP problem versus Planck scale physicsSep 02 1996Oct 22 1996We discuss conditions that should be satisfied by axion models for solving the strong CP problem. It has been observed that Planck scale effects may render the axion models ineffective if there are gauge invariant operators of dimension less than 10 which ... More
Unscrambling New Models for Higher-Energy PhysicsMar 03 2001There is strong evidence that new physical degrees of freedom and new phenomena exist and may be revealed in future collider experiments. The best hints of what this new physics might be are provided by electroweak symmetry breaking. I briefly review ... More
Higgs Compositeness from Top Dynamics and Extra DimensionsMar 19 1999The fundamental Higgs doublet may be replaced in the Standard Model by certain non-perturbative four-quark interactions, whose effect is to induce a composite Higgs sector responsible for electroweak symmetry breaking. A simple composite two-Higgs-doublet ... More
Testing Technicolor with Scalars at the First Muon ColliderFeb 06 1998An interesting class of models of dynamical electroweak symmetry breaking allows only the third generation fermions to acquire dynamical masses, such that the masses of the first two generations should be given by coupling to a nonstandard ``Higgs'' doublet. ... More
Leptophobic boson signals with leptons, jets and missing energyJun 14 2015Color-singlet gauge bosons with renormalizable couplings to quarks but not to leptons must interact with additional fermions ("anomalons") required to cancel the gauge anomalies. Analyzing the decays of such leptophobic bosons into anomalons, I show that ... More
Minimal Composite Higgs Model with Light BosonsAug 17 1999Sep 15 1999We analyze a composite Higgs model with the minimal content that allows a light Standard-Model-like Higgs boson, potentially just above the current LEP limit. The Higgs boson is a bound state made up of the top quark and a heavy vector-like quark. The ... More
Electroweak symmetry breaking as a consequence of compact dimensionsDec 14 1998Jul 22 1999It has been shown recently that the Higgs doublet may be composite, with the left-handed top-bottom doublet and a new right-handed anti-quark as constituents bound by some four-quark operators with nonperturbative coefficients. I show that these operators ... More
Chiral Compactification on a SquareJan 07 2004Sep 16 2004We study quantum field theory in six dimensions with two of them compactified on a square. A simple boundary condition is the identification of two pairs of adjacent sides of the square such that the values of a field at two identified points differ by ... More
Minimal $SU(3)\times SU(3)$ symmetry breaking patternsOct 04 2017We study the vacua of an $SU(3)\times SU(3)$-symmetric model with a bifundamental scalar. Structures of this type appear in various gauge theories such as the Renormalizable Coloron Model, which is an extension of QCD, or the Trinification extension of ... More
Heavy octets and Tevatron signals with three or four b jetsDec 28 2010Hypothetical color-octet particles of spin 0, pair-produced at hadron colliders through their QCD coupling, may lead to final states involving three or four b jets. We analyze kinematic distributions of the 3b final state that differentiate the scalar ... More
Universal Extra Dimensions and the Muon Magnetic MomentJun 13 2001We analyze the muon anomalous magnetic moment in the context of universal extra dimensions. Our computation shows that the bound from electroweak data on the size of these dimensions allows only a small shift in the muon magnetic moment given by Kaluza-Klein ... More
Coupling--mass mapping of di-jet peak searchesJun 11 2013Sep 15 2014We study hypothetical gauge bosons that may produce dijet resonances at the LHC. Simple renormalizable models include leptophobic Z' bosons or colorons that have flavor-independent couplings and decay into a color-singlet or -octet quark-antiquark pair, ... More
Hidden GeV-scale interactions of quarksApr 15 2014Apr 24 2014We explore quark interactions mediated by new gauge bosons of masses in the 0.3 - 50 GeV range. A tight upper limit on the gauge coupling of light Z' bosons is imposed by the anomaly cancellation conditions in conjunction with collider bounds on new charged ... More
Exotic Signals of Vectorlike QuarksDec 06 2016Jul 06 2018Vectorlike fermions are an important target for hadron collider searches. We show that the vectorlike quarks may predominantly decay via higher-dimensional operators into a quark plus a couple of other Standard Model fermions. Pair production of vectorlike ... More
Spin-Dependent Macroscopic Forces from New Particle ExchangeMay 31 2006Long-range forces between macroscopic objects are mediated by light particles that interact with the electrons or nucleons, and include spin-dependent static components as well as spin- and velocity-dependent components. We parametrize the long-range ... More
Interpretations of anomalous LHC events with electrons and jetsAug 05 2014Sep 07 2014The CMS Collaboration has recently reported some excess events in final states with electrons and jets, in searches for leptoquarks and $W'$ bosons. Although these excesses may be due to some yet-to-be-understood background mismodeling, it is useful to ... More
Negative contributions to S in an effective field theorySep 09 1997Sep 19 1997We show that an effective field theory that includes non-standard couplings between the electroweak gauge bosons and the top and bottom quarks may yield negative contributions to both the S and T oblique radiative electroweak parameters. We find that ... More
A W' boson near 2 TeV: predictions for Run 2 of the LHCJun 22 2015Oct 05 2015We present a renormalizable theory that includes a $W'$ boson of mass in the 1.8-2 TeV range, which may explain the excess events reported by the ATLAS Collaboration in a $WZ$ final state, and by the CMS Collaboration in $e^+\!e^- jj$, $Wh^0$ and $jj$ ... More
Collider Tests of the Renormalizable Coloron ModelFeb 08 2018The coloron, a massive version of the gluon present in gauge extensions of QCD, has been searched for at the LHC as a dijet or top quark pair resonance. We point out that in the Renormalizable Coloron Model (ReCoM) with a minimal field content to break ... More
Number of Fermion Generations Derived from Anomaly CancellationFeb 01 2001Jun 07 2001We prove that global anomaly cancellation requires more than one generation of quarks and leptons, provided that the standard model fields propagate in two universal extra dimensions. Furthermore, if the fermions of different generations have the same ... More
GeV-scale dark matter: production at the Main InjectorOct 06 2014Assuming that dark matter particles interact with quarks via a GeV-scale mediator, we study dark matter production in fixed target collisions. The ensuing signal in a neutrino near detector consists of neutral-current events with an energy distribution ... More
Exotic Signals of Vectorlike QuarksDec 06 2016Vectorlike fermions are an important target for hadron collider searches. We show that the vectorlike quarks may predominantly decay via higher-dimensional operators into a quark plus a couple of other Standard Model fermions. Pair production of vectorlike ... More
Heavy Higgs bosons and the 2 TeV $W'$ bosonJul 07 2015Sep 27 2015The hints from the LHC for the existence of a $W'$ boson of mass around 1.9 TeV point towards a certain $SU(2)_L\times SU(2)_R\times U(1)_{B-L}$ gauge theory with an extended Higgs sector. We show that the decays of the $W'$ boson into heavy Higgs bosons ... More
Collider Tests of the Renormalizable Coloron ModelFeb 08 2018Sep 07 2018The coloron, a massive version of the gluon present in gauge extensions of QCD, has been searched for at the LHC as a dijet or top quark pair resonance. We point out that in the Renormalizable Coloron Model (ReCoM) with a minimal field content to break ... More
Six-Dimensional Gauge Theory on the Chiral SquareJun 30 2005We construct gauge theories in two extra dimensions compactified on the chiral square, which is a simple compactification that leads to chiral fermions in four dimensions. Stationarity of the action on the boundary specifies the boundary conditions for ... More
Accumulating evidence for nonstandard leptonic decays of D_s mesonsMar 04 2008Jul 14 2008The measured rate for D_s -> l nu decays, where l is a muon or tau, is larger than the standard model prediction, which relies on lattice QCD, at the 3.8 sigma level. We discuss how robust the theoretical prediction is, and we show that the discrepancy ... More
Leptons and photons at the LHC: cascades through spinless adjointsMar 21 2007We study the hadron collider phenomenology of (1,0) Kaluza-Klein modes along two universal extra dimensions compactified on the chiral square. Cascade decays of spinless adjoints proceed through tree-level 3-body decays involving leptons as well as one-loop ... More
Vacuum Instability in Low-Energy Supersymmetry Breaking ModelsAug 01 1996Sep 04 1996We show that for the simplest models of gauge mediated supersymmetry breaking, including all existing models, the true vacuum will not preserve QCD if it communicates supersymmetry breaking to the visible sector. We show that the desired supersymmetry ... More
Top-Bottom Splitting in Technicolor with Composite ScalarsJul 22 1998We present a model of dynamical electroweak symmetry breaking in which the splitting between the top and bottom quark masses arises naturally. The W and Z masses are produced by a minimal technicolor sector, the top quark mass is given by the exchange ... More
Uplifted supersymmetric Higgs regionJan 19 2010May 26 2010We show that the parameter space of the Minimal Supersymmetric Standard Model includes a region where the down-type fermion masses are generated by the loop-induced couplings to the up-type Higgs doublet. In this region the down-type Higgs doublet does ... More
Resonances from Two Universal Extra DimensionsJan 23 2006Aug 21 2007Standard model gauge bosons propagating in two universal extra dimensions give rise to heavy spin-1 and spin-0 particles. The lightest of these, carrying Kaluza-Klein numbers (1,0), may be produced only in pairs at colliders, whereas the (1,1) modes, ... More
W' signatures with odd Higgs particlesDec 06 2013Feb 16 2014We point out that W' bosons may decay predominantly into Higgs particles associated with their broken gauge symmetry. We demonstrate this in a renormalizable model where the W' and W couplings to fermions differ only by an overall normalization. This ... More
Coupling spans of the Higgs-like bosonOct 11 2012Feb 27 2013Using the LHC and Tevatron data, we set upper and lower limits on the total width of the Higgs-like boson. The upper limit is based on the well-motivated assumption that the Higgs coupling to a W or Z pair is not much larger than in the Standard Model. ... More
Massive color-octet bosons and pairs of resonances at hadron collidersSep 14 2007Feb 18 2009We analyze collider signatures of massive color-octet bosons whose couplings to quarks are suppressed. Gauge invariance forces the octets to couple at tree level only in pairs to gluons, with a strength set by the QCD gauge coupling. For a spin-1 octet, ... More
Anomaly-Free Sets of FermionsOct 13 2005We present new techniques for finding anomaly-free sets of fermions. Although the anomaly cancellation conditions typically include cubic equations with integer variables that cannot be solved in general, we prove by construction that any chiral set of ... More
Signals of a 2 TeV $W'$ boson and a heavier $Z'$ bosonNov 06 2015May 02 2016We construct an $SU(2)_L\times SU(2)_R\times U(1)_{B-L}$ model with a Higgs sector that consists of a bidoublet and a doublet, and with a right-handed neutrino sector that includes one Dirac fermion and one Majorana fermion. This model explains the Run ... More
Analytic Estimates of the QCD Corrections to Neutrino-Nucleus ScatteringOct 13 2003We study the QCD corrections to neutrino deep-inelastic scattering on a nucleus, and analytically estimate their size. For an isoscalar target, we show that the dominant QCD corrections to the ratio of the neutral- to charged-current events are suppressed ... More
Weak-triplet, color-octet scalars and the CDF dijet excessApr 14 2011Jun 27 2011We extend the standard model to include a weak-triplet and color-octet scalar. This `octo-triplet' field consists of three particles, two charged and one neutral, whose masses and renormalizable interactions depend only on two new parameters. The charged ... More
Semileptonic decays of the standard Higgs bosonDec 18 2009The Higgs boson decay into a pair of real or virtual W bosons, with one of them decaying leptonically, is predicted within the Standard Model to have the largest branching fraction of all Higgs decays that involve an isolated electron or muon, for M_h ... More
Quark and lepton masses from top loopsMay 07 2008Sep 05 2008Assuming that the leptons and quarks other than top are massless at tree level, we show that their masses may be induced by loops involving the top quark. As a result, the generic features of the fermion mass spectrum arise from combinations of loop factors. ... More
Prospects for top-prime quark discovery at the TevatronFeb 05 2009Apr 13 2009We show that a top-prime quark as heavy as 600 GeV can be discovered at the Tevatron, provided it is resonantly pair-produced via a vector color octet. If the top-prime originates from a vectorlike quark, then the production of a single top-prime in association ... More
Electroweak Symmetry Breaking via Top Condensation SeesawDec 09 1997Aug 12 1998We propose a new mechanism in which all of the electroweak symmetry breaking is driven by a natural top quark condensate, produced by topcolor interactions at a multi-TeV scale. The scheme allows the observed top quark mass, and acceptable T and S parameters, ... More
Composite Vectorlike FermionsSep 04 2014We study a dynamical mechanism that generates a composite vectorlike fermion, formed by the binding of an $N$-tuplet of elementary chiral fermions to an $N$-tuplet of scalars. Deriving the properties of the composite fermion in the large $N$ limit, we ... More
Light Axion within the Next-to-Minimal Supersymmetric Standard ModelAug 18 2000We analyze the Higgs sector in the Next-to-Minimal Supersymmetric Standard Model, emphasizing the possibility of a light CP-odd scalar (axion) in the spectrum. We compute the coupling of the Standard-Model-like Higgs boson to a pair of axions, and show ... More
Generic and Chiral Extensions of the Supersymmetric Standard ModelNov 12 1998We construct extensions of the Standard Model in which the gauge symmetries and supersymmetry prevent the dangerously large effects that may potentially be induced in a supersymmetric standard model by Planck scale physics. These include baryon number ... More
Gauge Trimming of Neutrino MassesDec 02 2006We show that under a new U(1) gauge symmetry, which is non-anomalous in the presence of one ``right-handed neutrino'' per generation and consistent with the standard model Yukawa couplings, the most general fermion charges are determined in terms of four ... More
Electroweak symmetry breaking by extra dimensionsApr 07 2000Electroweak symmetry breaking may be naturally induced by the observed quark and gauge fields in extra dimensions without a fundamental Higgs field. We show that a composite Higgs doublet can arise as a bound state of $(t, b)_L$ and a linear combination ... More
Bounds on Universal Extra DimensionsDec 08 2000Jun 29 2001We show that the bound from the electroweak data on the size of extra dimensions accessible to all the standard model fields is rather loose. These "universal" extra dimensions could have a compactification scale as low as 300 GeV for one extra dimension. ... More
Higgs Underproduction at the LHCDec 09 2011Jan 03 2012We show that production of the Higgs boson through gluon-fusion may be suppressed in the presence of colored scalars. Substantial destructive interference between the top quark diagrams and colored scalar diagrams is possible due to cancellations between ... More
CP violation in B_s mixing from heavy Higgs exchangeMay 23 2010Jun 18 2010The anomalous dimuon charge asymmetry reported by the D0 Collaboration may be due to the tree-level exchange of some spin-0 particles that mediate CP violation in B_s-\bar{B}_s meson mixing. We show that for a range of couplings and masses, the heavy ... More
Multi-step production of a diphoton resonanceMay 27 2016Assuming that the mass peak at 750 GeV reported by the ATLAS and CMS Collaborations is due to a spin-0 particle that decays into two photons, we present two weakly-coupled renormalizable models that lead to different production mechanisms. In one model, ... More
Higgs Boson Decays to CP-odd Scalars at the Tevatron and BeyondMay 31 2000In extended Higgs models, the Higgs boson may decay into a pair of light CP-odd scalars, with distinctive collider signatures. We study the ensuing Higgs signals at the upgraded Tevatron, considering the subsequent decays of the scalars into pairs of ... More
Proton Stability in Six DimensionsJul 05 2001Oct 09 2001We show that Lorentz and gauge invariance explain the long proton lifetime within the standard model in six dimensions. The baryon-number violating operators have mass dimension 15 or higher. Upon TeV-scale compactification of the two universal extra ... More
Multi-step production of a diphoton resonanceMay 27 2016Nov 17 2016Among the questions that would be raised by the observation of a new resonance at the LHC, particularly pressing are those concerning the production mechanism: What is the initial state? Is the resonance produced independently or in association with other ... More
A Chiral Supersymmetric Standard ModelJul 03 1998We propose a supersymmetric extension of the Standard Model with an extra U(1) gauge symmetry, so that all supersymmetric mass terms, including the $\mu$-term, are forbidden by the gauge symmetries. Supersymmetry is broken dynamically which results in ... More
Higgs mass from compositeness at a multi-TeV scaleNov 22 2013Aug 19 2014Within composite Higgs models based on the top seesaw mechanism, we show that the Higgs field can arise as the pseudo Nambu-Goldstone boson of the broken U(3)_L chiral symmetry associated with a vector-like quark and the t-b doublet. As a result, the ... More
Coxeter Groups, Wavelets, Multiresolution and SamplingOct 18 2007In this short note we discuss the interplay between finite Coxeter groups and construction of wavelet sets, generalized multiresolution analysis and sampling.
Spinless photon dark matter from two universal extra dimensionsJun 25 2007Oct 04 2007We explore the properties of dark matter in theories with two universal extra dimensions, where the lightest Kaluza-Klein state is a spin-0 neutral particle, representing a six-dimensional photon polarized along the extra dimensions. Annihilation of this ... More
Right-handed neutrinos and the 2 TeV $W'$ bosonAug 17 2015Dec 16 2015The CMS $e^+ e^- jj$ events of invariant mass near 2 TeV are consistent with a $W'$ boson decaying into an electron and a right-handed neutrino whose TeV-scale mass is of the Dirac type. We show that the Dirac partner of the right-handed electron-neutrino ... More
Nonexotic Neutral Gauge BosonsDec 04 2002Jul 17 2003We study theoretical and experimental constraints on electroweak theories including a new color-singlet and electrically-neutral gauge boson. We first note that the electric charges of the observed fermions imply that any such Z' boson may be described ... More
Neutrinos Vis-a-vis the Six-Dimensional Standard ModelJan 15 2002Mar 25 2002We examine the origin of neutrino masses and oscillations in the context of the six-dimensional standard model. The space-time symmetries of this model explain proton stability and forbid Majorana neutrino masses. The consistency of the six-dimensional ... More
Electroweak Symmetry Breaking and Extra DimensionsDec 14 1999Aug 18 2000Electroweak symmetry can be naturally broken by observed quark and gauge fields in various extra-dimensional configurations. No new {\it fundamental} fields are required below the quantum gravitational scale ($\sim$ 10 - 100 TeV). We examine schemes in ... More
Gauge Coupling Unification with Extra Dimensions and Gravitational Scale EffectsJun 10 1999Jul 08 1999We study gauge coupling unification in the presence of extra dimensions compactified at a few TeV. Achieving unification requires a large number of gauge boson Kaluza-Klein excitations lighter than the string scale, such that the higher-dimensional gauge ... More
Dark matter beams at LBNFDec 12 2015High-intensity neutrino beam facilities may produce a beam of light dark matter when protons strike the target. Searches for such a dark matter beam using its scattering in a nearby detector must overcome the large neutrino background. We characterize ... More
Ultraheavy resonances at the LHC: beyond the QCD backgroundOct 22 2018We study the theory and some experimental hints of ultraheavy resonances at the LHC. The production of an ultraheavy narrow particle may have a larger rate than the QCD background even when the final state includes only hadronic jets. We consider two ... More
Wavelet sets without groupsOct 18 2007Most of the examples of wavelet sets are for dilation sets which are groups. We find a necessary and sufficient condition under which subspace wavelet sets exist for dilation sets of the form $A B$, which are not necessarily groups. We explain the construction ... More
Universal Spectrum of 2d Conformal Field Theory in the Large c LimitMay 20 2014Sep 19 2014Two-dimensional conformal field theories exhibit a universal free energy in the high temperature limit $T \to \infty$, and a universal spectrum in the Cardy regime, $\Delta \to \infty$. We show that a much stronger form of universality holds in theories ... More
Differential equations and high-energy expansion of two--loop diagrams in D dimensionsSep 19 2005Oct 18 2005New method of calculation of master integrals using differential equations and asymptotical expansion is presented. This method leads to the results exact in space-time dimension $D$ having the form of the convergent power series. As an application of ... More
Z-prime Gauge Bosons at the TevatronAug 06 2004We study the discovery potential of the Tevatron for a Z-prime gauge boson. We introduce a parametrization of the Z-prime signal which provides a convenient bridge between collider searches and specific Z-prime models. The cross section for p pbar -> ... More
Self-Breaking of the Standard Model Gauge SymmetryJun 20 2000Nov 03 2000If the gauge fields of the Standard Model propagate in TeV-size extra dimensions, they rapidly become strongly coupled and can form scalar bound states of quarks and leptons. If the quarks and leptons of the third generation propagate in 6 or 8 dimensions, ... More
Top Quark Seesaw Theory of Electroweak Symmetry BreakingSep 21 1998Nov 03 1998We study electroweak symmetry breaking involving the seesaw mechanism of quark condensation. These models produce a composite Higgs boson involving the left-handed top quark, yet the top mass arises naturally at the observed scale. We describe a schematic ... More
Magnetic Instability in Strongly Correlated SuperconductorsMar 03 2003Recently a new phenomenological Hamiltonian has been proposed to describe the superconducting cuprates. This so-called Gossamer Hamiltonian is an apt model for a superconductor with strong on-site Coulomb repulsion betweenthe electrons. It is shown that ... More
Transport optimization on complex networksJan 09 2007We present a comparative study of the application of a recently introduced heuristic algorithm to the optimization of transport on three major types of complex networks. The algorithm balances network traffic iteratively by minimizing the maximum node ... More
Optimal routing on complex networksJul 01 2006Jul 08 2006We present a novel heuristic algorithm for routing optimization on complex networks. Previously proposed routing optimization algorithms aim at avoiding or reducing link overload. Our algorithm balances traffic on a network by minimizing the maximum node ... More
Isospin Breaking and the Top-Quark Mass in Models of Dynamical Electroweak Symmetry BreakingJun 28 1995Sep 20 1995In this talk we review the physics of top-quark mass generation in models of dynamical electroweak symmetry breaking and the constraints on this physics arising from limits on the deviation of the weak interaction $\rho$-parameter from one. We then discuss ... More
On bounded elementary generation for $SL_n$ over polynomial ringsJan 03 2019Let $F[X]$ be the polynomial ring over a finite field $F$. It is shown that, for $n\geq 3$, the special linear group $SL_n(F[X])$ is boundedly generated by the elementary matrices.
Seeley's Theory of Pseudodifferential Operators on OrbifoldsDec 30 1999We present the theory of pseudodifferential operators acting on a vector orbibundle over an orbifold, construct the zeta function of an elliptic pseudodifferential operator and show the existence of a meromorphic extension to the complex plane with at ... More
Syntactic Analysis Based on Morphological Characteristic Features of the Romanian LanguageJan 09 2013This paper refers to the syntactic analysis of phrases in Romanian, as an important process of natural language processing. We will suggest a real-time solution, based on the idea of using some words or groups of words that indicate grammatical category; ... More
Proper isometric actions of hyperbolic groups on $L^p$-spacesFeb 13 2012Jun 10 2013We show that every non-elementary hyperbolic group $\G$ admits a proper affine isometric action on $L^p(\bd\G\times \bd\G)$, where $\bd\G$ denotes the boundary of $\G$ and $p$ is large enough. Our construction involves a $\G$-invariant measure on $\bd\G\times ... More
The Motivic Cofiber of $τ$Jan 17 2017Consider the Tate twist $\tau \in H^{0,1}(S^{0,0})$ in the mod 2 cohomology of the motivic sphere. After 2-completion, the motivic Adams spectral sequence realizes this element as a map $\tau \colon S^{0,-1} \to S^{0,0}$, with cofiber $C\tau$. We show ... More
The first eigenvalue of the Dirac operator on locally reducible Riemannian manifoldsFeb 25 2005We prove a lower estimate for the first eigenvalue of the Dirac operator on a compact locally reducible Riemannian spin manifold with positive scalar curvature. We determine also the universal covers of the manifolds on which the smallest possible eigenvalue ... More
An Extension of the Work of V. Guillemin on Complex Powers and Zeta Functions of Elliptic Pseudodifferential OperatorsMay 09 1997May 17 1997The purpose of this note is to extend the results of V. Guillemin on elliptic self-adjoint pseudodifferential operators of order one, from operators defined on smooth functions on a closed manifold to operators defined on smooth sections in a vector bundle ... More
Superradiant instability in AdSAug 05 2016The phenomenon of superradiance in the context of asymptotically global AdS spacetimes is investigated with particular accent on its effect on the stability of the systems under consideration. To this end, the concept of an asymptotically AdS spacetime ... More
Weak index pairs and the Conley index for discrete multivalued dynamical systems. Part II: properties of the indexJun 28 2017Motivation to revisit the Conley index theory for discrete multivalued dynamical systems stems from the needs of broader real applications, in particular in sampled dynamics or in combinatorial dynamics. The new construction of the index in [B. Batko ... More
On operator norms for hyperbolic groupsSep 28 2015We estimate the operator norm of radial non-negative functions on hyperbolic groups. As a consequence, we show that several forms of Haagerup's inequality are optimal.
On the Relation Between the Randomized Extended Kaczmarz Algorithm and Coordinate DescentMay 27 2014Aug 30 2014In this note we compare the randomized extended Kaczmarz (EK) algorithm and randomized coordinate descent (CD) for solving the full-rank overdetermined linear least-squares problem and prove that CD needs less operations for satisfying the same residual-related ... More
Cubulating spaces with wallsAug 29 2003May 24 2004We describe a correspondence between spaces with walls and CAT(0) cube complexes.
A brief introduction to Spectral Graph TheorySep 26 2016Expanded lecture notes. Preliminary version, comments are welcome.
Potentials for $\mathcal{A}$-quasiconvexityMar 02 2018Apr 02 2019We show that each constant rank operator $\mathcal{A}$ admits an exact potential $\mathbb{B}$ in frequency space. We use this fact to show that the notion of $\mathcal{A}$-quasiconvexity can be tested against compactly supported fields. We also show that ... More
Phase Conjugation and Negative Refraction Using Nonlinear Active MetamaterialsAug 11 2010We present experimental demonstration of phase conjugation using nonlinear metamaterial elements. Active split-ring resonators loaded with varactor diodes are demonstrated theoretically to act as phase-conjugating or time-reversing discrete elements when ... More
Upper limits on the luminosity of the progenitor of type Ia supernova SN2014JFeb 12 2014We analysed archival data of Chandra pre-explosion observations of the position of SN2014J in M82. No X-ray source at this position was detected in the data, and we calculated upper limits on the luminosities of the progenitor. These upper limits allow ... More
Linear Collider PhysicsJul 18 2001We report on a study of the physics potential of linear $e^+e^-$ colliders. Although a linear collider (LC) would support a broad physics program, we focus on the contributions that could help elucidate the origin of electroweak symmetry breaking. Many ... More
Signals of Dynamical Supersymmetry Breaking in a Hidden SectorOct 04 1996If supersymmetry is dynamically broken in a hidden sector, the gauginos typically have unacceptably small masses. This situation can be corrected if a non-Abelian gauge interaction becomes strong at a scale of order 1 TeV and induces dynamical gaugino ... More
Estimates of convolution operators of functions from $L_{2π}^{p(x)}$Apr 05 2019We generalize and slight improve the result of I. I. Sharapudinov [Mat. Zametki, 1996, Volume 59, Issue 2, 291--302]. Some applications to the de la Vall\'{e}e Poussin operator will also be given.
Non-uniform continuity of the semiflow map associated to the porous medium equationJan 06 2014We prove that the semiflow map associated to the evolution problem for the porous medium equation (PME) is real-analytic as a function of the initial data in $H^s(\mathbb{S})$, $s>7/2,$ at any fixed positive time, but it is not uniformly continuous. More ... More
Heat kernel of fractional Laplacian in conesMar 12 2009We give sharp estimates for the transition density of the isotropic stable L\'evy process killed when leaving a right circular cone.