126144922
Production of a pair of $t \bar{t}$ quarks near threshold
119379184
Radiative corrections to the hadronic cross-section measurement at DA$\Phi$NE
Abstract. The hadronic invariant mass distribution for the process of electron–positron annihilation into a pair of charged pions accompanied by a photon radiated from the initial state has been studied for the region of DA$\Phi$NE energies. The Born cross–section and the electromagnetic radiative corrections to it are calculated for realistic conditions of the KLOE detector. The dependence on the physical parameters which define the event selection is obtained.
125850380
Multiple Hadron Production in Parton {QCD} Jets
124029542
On the sensitivity of the inclusive distributions in parton jets to the coherence effects in QCD gluon cascades
The KNO multiplicity distributions and properties of two-particle correlations in QCD jets are considered in the framework of the perturbative approach accounting for effects of the coherence in the soft gluon bremsstrahlung.
119436494
QCD Interconnection Effects
Heavy objects like the W, Z and t are short-lived compared with typical hadronization times. When pairs of such particles are produced, the subsequent hadronic decay systems may therefore become interconnected. We study such potential effects at Linear Collider energies.
117871006
Pomeron universality from identical pion correlations at the LHC
Abstract Bose–Einstein correlations of identical pions produced in high-energy pp collisions at the LHC allow a probe of the Pomeron exchange mechanism. The size of the domain which emits the pions depends on the multiplicity of events, but not on the collider energy. This confirms the universal structure of Pomeron exchange. The data at relatively low multiplicities indicate that the size of the source created by one-Pomeron exchange is much less than the size of the proton.
119032265
Notes on soliton bound state problems in gauge theory and string theory
We review four basic examples where string theory and/or field theory dualities predict the existence of soliton bound-states. These include the existence of threshold bound-states of D0 branes required by IIA/M duality and the closely-related bound-states of instantons in the maximally supersymmetric five dimensional gauge theory. In the IIB theory we discuss (p,q)-strings as bound-states of D and F strings, as well as the corresponding bound-states of monopoles and dyons in N=4 supersymmetric Yang-Mills theory whose existence was predicted by Sen. In particular we consider the L^2-index theory relevant for counting these states. In each case we show that the bulk contribution to the index can be evaluated by relating it to an instanton effect in the corresponding theory with a compact Euclidean time dimension. The boundary contribution to the index can be determined by considering the asymptotic regions of the relevant moduli space.
9444196
From branes to branes
Abstract We use the ‘branes within branes’ approach to study the appearance of stable ( p −2)-branes and unstable ( p −1)-branes in type II string theory from p -brane– p -antibrane pairs. Our goal is to describe the emergence of these lower-dimensional branes from brane–antibrane pairs in string theory using a tractable gauge theory language. This is achieved by suspending the original p -brane– p -antibrane pair between two ( p +2)-branes, and describing its dynamics in terms of the worldvolume gauge theory on the spectator ( p +2)-branes. Instantons, monopoles, sphalerons and their higher-dimensional generalizations in this worldvolume gauge theory correspond to stable (BPS) and unstable (non-BPS) branes in string theory. Collisions of stable branes with corresponding antibranes and production of lower-dimensional branes in string theory are described in a straightforward way in gauge theory. Tachyonic modes on the p -brane– p -antibrane worldvolume do not appear in our analysis since we work on the worldvolume of the spectator ( p +2)-branes. Our results on brane descent relations are in agreement with Sen's tachyon condensation approach.
8182637
Recursion relations for gauge theory amplitudes with massive particles
We derive general tree-level recursion relations for amplitudes which include massive propagating particles. As an illustration, we apply these recursion relations to scattering amplitudes of gluons coupled to massive scalars. We provide new results for all amplitudes with a pair of scalars and n ≤ 4 gluons. These amplitudes can be used as building blocks in the computation of one-loop 6-gluon amplitudes using unitarity based methods.
15161694
Yang-Mills instantons in the large N limit and the AdS / CFT correspondence
Abstract We examine a certain 16-fermion correlator in N =4 supersymmetric SU(N) gauge theory in 4 dimensions. Generalizing recent SU(2) results of Bianchi, Green, Kovacs and Rossi, we calculate the exact N-dependence of the effective 16-fermion vertex at the 1-instanton level, and find precise agreement in the large-N limit with the prediction of the type IIB superstring on AdS5×S5. This suggests that the string theory prediction for the 1-instanton amplitude considered here is not corrected by higher-order terms in the α′ expansion.
15213237
Collinear limits in QCD from MHV rules
We consider multi-parton collinear limits of QCD amplitudes at tree level. Using the MHV formalism we specify the underlying analytic structure of the resulting multi-collinear splitting functions. We derive general results for these splitting functions that are valid for specific numbers of negative helicity partons and an arbitrary number of positive helicity partons (or vice versa).