14767755
Instanton calculations in the β-deformed AdS/CFT correspondence
We consider non-perturbative effects in the β-deformed = 4 supersymmetric gauge theory in the context of the AdS/CFT correspondence. We concentrate on certain types of the n-point correlation functions of the Yang-Mills operators which correspond to the lowest Kaluza-Klein modes propagating on the dual supergravity background found by Lunin and Maldacena in [1]. In particular, we calculate all multi-instanton contributions to these correlators in the β-deformed SYM and find a compelling agreement with the results expected in supergravity.
14098895
Gluino condensate and magnetic monopoles in supersymmetric gluodynamics
We examine supersymmetric SU(N) gauge theories on R3 × S1 with a circle of circumference β. These theories interpolate between four-dimensional N = 1 pure gauge theory for β = ∞ and three-dimensional N = 2 gauge theory for β = 0. The dominant field configurations of the R3 × S1 SU(N) theories in the semi-classical regime arise from N varieties of monopole. Periodic instanton configurations correspond to mixed configurations of N single monopoles of the N different types. We semi-classically evaluate the non-perturbatively generated superpotential of the R3 × S1 theory and hence determine its vacuum structure. to the gluino condensate in these theories and take the decompactification limit β = ∞. In this way we obtain a value for the gluino condensate in the four-dimensional N = 1 supersymmetric SU(N) Yang-Mills theory, which agrees with the previously known ‘weak coupling’ expression but not with the ‘strong coupling’ expression derived in the early literature solely from instanton considerations. Moreover, we discover that the superpotential gives a mass to the dual (magnetic) photon, which implies confinement of the original electric photon and disappearance of all the massless modes.
119379193
The calculus of many instantons
We describe the modern formalism, ideas and applications of the instanton calculus for gauge theories with, and without, supersymmetry. Particular emphasis is put on developing a formalism that can deal with any number of instantons. This necessitates a thorough review of the ADHM construction of instantons with arbitrary charge and an in-depth analysis of the resulting moduli space of solutions. We review the construction of the ADHM moduli space as a hyper-Kahler quotient. We show how the functional integral in the semi-classical approximation reduces to an integral over the instanton moduli space in each instanton sector and how the resulting matrix partition function involves various geometrical quantities on the instanton moduli space: volume form, connection, curvature, isometries, etc. One important conclusion is that this partition function is the dimensional reduction of a higher- dimensional gauged linear sigma model which naturally leads us to describe the relation of the instanton calculus to D-branes in string theory. Along the way we describe powerful applications of the calculus of many instantons to supersymmetric gauge theories including (i) the gluino condensate puzzle in N = 1 theories (ii) Seiberg-Witten theory in N = 2 theories; and (iii) the AdS/CFT correspondence in N = 2 and N = 4 theories. Finally, we brielfy review the modifications of the instanton calculus for a gauge theory defined on a non-commutative spacetime and we also describe a new method for calculating instanton processes using a form of localization on the instanton moduli space.
119236962
Travels on the squark-gluino mass plane
Institut fur Theoretische Physik, Universitat Heidelberg, Germany(Dated: September 12, 2011)Soft supersymmetry breaking appears in the weak-scale e ective action but is usually generated athigher scales. For these models the structure of the renormalization group evolution down to theelectroweak scale leaves only part of the squark-gluino and slepton-gaugino mass planes accessible.Our observations divide these physical mass planes into three wedges: the rst can be reached byall models of high-scale breaking; the second can only be populated by models with a low mediationscale; in the third wedge squarks and gluinos would have to be described by an exotic theory. Allusual benchmark points reside in the rst wedge, even though an LHC discovery in the third wedge
34905319
Minkowski space non-Abelian classical solutions with noninteger winding number change.
Working in a spherically symmetric ansatz in Minkowski space, we discover new solutions to the classical equations of motion of pure SU(2) gauge theory. These solutions represent spherical shells of energy, which move inward near the speed of light at early times, excite the region of space around the origin at intermediate times, and move outward at late times. The solutions change the winding number in bounded regions centered at the origin by noninteger amounts. They also produce a noninteger topological charge in these regions. We show that the previously discovered solutions of Luescher and Schechter also have these properties.
119447895
Multi-gluon collinear limits from MHV diagrams
We consider the multi-collinear limit of multi-gluon QCD amplitudes at tree level. We use the MHV rules for constructing colour ordered tree amplitudes and the general collinear factorization formula to derive timelike splitting functions that are valid for specific numbers of negative helicity gluons and an arbitrary number of positive helicity gluons (or vice versa). As an example we present new results describing the collinear limits of up to six gluons.
56466072
Angular distribution of particle flows and perturbative QCD predictions
Abstract. We discuss the predictions of perturbative QCD for angular flows of final state particles in two and three jet events including their cms energy and jet resolution (ycut) dependence. The simple analytical formulae for gluon bremsstrahlung from primary partons, modified for gluon cascading, reproduce the main features of the experimental data well. For ycut-selected events, the particle flow is derived from a superposition of colour dipoles in much the same way that photon radiation is derived from electric dipoles.
121236874
A phenomenological investigation of the string effect
We present results from Monte Carlo calculations of the string effect and the double inclusive correlation of particle flows for three-fold symmetric three-jet events in e+e− annihilation reactions at different energies. We find that the perturbative phase of the jet evolution quickly becomes dominant as energy increases.
305020
Insight into double-pomeron-exchange Higgs production and backgrounds
Abstract We quantify the central inclusive background contributions to exclusive Higgs production at the LHC arising from double-pomeron-exchange processes. We consider the H → b b ¯ signal. We study processes mediated by the fusion of two ‘hard’ pomerons, and also by the fusion of ‘soft’ pomerons. The latter background is found to be very small, and the former is found to be less than the exclusive signal.
17004606
Gluon radiation and energy losses in top quark production
Abstract The emission of energetic gluons in t t production in e+e− annihilation can have important experimental consequences, in particular on top quark mass measurements. We present compact, analytical expressions for the gluon energy distribution and its average value at first order in QCD perturbation theory. Our results are valid for arbitrary masses, collision energies and production currents. We pay particular attention to top quark production near threshold, and show that in certain cases the soft gluon approximation is insufficient to describe the radiation spectrum.
16672716
Soft diffraction at the LHC and properties of the Pomeron
We briefly describe a model for soft diffraction. The model description of ISR, SppS and Tevatron data, and the predictions of the total, elastic, single and double diffractive cross sections at the LHC can be found in the original paper. Here we address issues raised at Diffraction 2000, in particular concerning the nature of the resulting Pomeron trajectory.