14016091
Multi - instantons and Maldacena's conjecture
We examine certain n-point functions Gn in = 4 supersymmetric SU(N) gauge theory at the conformal point. In the large-N limit, we are able to sum all leading-order multi-instanton contributions exactly. We find compelling evidence for Maldacena's conjecture: (1) The large-N k-instanton collective coordinate space has the geometry of AdS5 × S5, (2) In exact agreement with type IIB superstring calculations, at the k-instanton level, Gn = N1/2g8kn−7/2e−8π2kg2∑d|kd−2Fn(x1,...,xn), where Fn is identical to a convolution of n bulk-to-boundary SUGRA propagators.
14575937
The Instanton Hunter's guide to supersymmetric SU(N) gauge theories
Abstract We present a compendium of results for ADHM multi-instantons in SU ( N ) SUSY gauge theories, followed by applications to N = 2 supersymmetric models. Extending recent SU (2) work, and treating the N = 1 and N = 2 cases in parallel, we construct: (i) the ADHM supermultiplet, (ii) the multi-instanton action, and (iii) the collective coordinate integration measure. Specializing to N = 2, we then give a closed formula for F k , the k -instanton contribution to the prepotential, as a finite-dimensional collective coordinate integral. This amounts to a weak-coupling solution, in quadratures, of the low-energy dynamics of N = 2 SQCD, without appeal to duality. As an application, we calculate F 1 for all SU ( N ) and any number of flavors N F ; for N F N − 2 and N F = 2 N − 1 we confirm previous instanton calculations and agree with the proposed hyper-elliptic curve solutions. For N F = 2 N − 2 and N F = 2 N with N > 3 we obtain new results, which in the latter case we do not understand how to reconcile with the curves.
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
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.
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.
116914349
Oscillation phenomena on neutral B meson systems
Mixing and CP-violation effects in tagged beams of neutral B mesons are studied. Various oscillations of the yield of decay products are discussed. One type is related to B/sup 0/bold-arrow-left-rightB-bar/sup 0/ transitions and another to CP violation in the decay. B/sup 0//sub s/ mesons are the most promising for the observation of such effects. In the standard model, exclusive decays of B/sup 0//sub s/ mesons related to the transition b..-->..uu-bard are the best for the observation of CP violation in B mesons. Departures from the standard model leading to modification of the mixing and CP-violation parameters are also discussed.
126008780
Collective {QCD} Effects in the Structure of Final Multi - Hadron States. (In Russian)
18084904
Diffractive Higgs production
We review the advantages of observing exclusive diffractive Higgs production at the LHC. We note the importance of the Sudakov form factor in predicting the event rate. We discuss briefly other processes which may be used as `standard candles'.
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.
118925449
Inelastic $J/\psi$ and $\Upsilon$ hadroproduction
Abstract.We consider the prompt hadroproduction of $J/\psi, \psi'$ and the $\Upsilon (1S,2S,3S)$ states caused by the fusion of a symmetric colour-octet state, (gg)8s, and an additional gluon. The cross sections are calculated in leading-order perturbative QCD. We find a considerable enhancement in comparison with previous perturbative QCD predictions. Indeed, the resulting cross sections are found to be consistent with the values measured at the Tevatron and RHIC, without the need to invoke non-perturbative ‘colour-octet’ type of contributions.