121957358
On specific QCD properties of heavy quark fragmentation ('dead cone')
It is the restriction on the phase space of emitting gluons connected with the kinematics of a heavy quark Q=c, b, . . . which determines the difference of the QCD jet produced by Q from that of ordinary light (practically massless) quarks q=u, d, s. The authors consider the Q-quark as relativistic (EQ>>MQ, Theta 0 identical to MQ/EQ<<1) and taking care of logarithmic effects ignoring small (power) corrections of the order of Theta 0.
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.
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.
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.
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.
2910926
MULTI-INSTANTONS, THREE-DIMENSIONAL GAUGE THEORY, AND THE GAUSS-BONNET-CHERN THEOREM
Abstract We calculate multi-instanton effects in a three-dimensional gauge theory with N = 8 supersymmetry and gauge group SU (2). The k -instanton contribution to an eight-fermion correlator is found to be proportional to the Gauss-Bonnet-Chem integral of the Gaussian curvature over the centered moduli space of charge- k BPS monopoles, M k . For k = 2 the integral can be evaluated using the explicit metric on M 2 found by Atiyah and Hitchin. In this case the integral is equal to the Euler character of the manifold. More generally the integral is the volume contribution to the index of the Euler operator on M k which may differ from the Euler character by a boundary term. We conjecture that the boundary terms vanish and evaluate the multi-instanton contributions using recent results for the cohomology of M k We comment briefly on the implications of our result for a recently proposed test of M(atrix) theory.
121305872
Instanton vacuum in thermal QCD
The effects of instanton-anti-instanton interactions in high-temperature QCD with colour SU(2) are studied with and without quarks. The instanton potential proves to have no repulsive core, thus creating troubles with the definition of nonperturbative contributions to physical quantities. Also the chiral condensate is calculated, and it is shown to vanish if number of quark flavoursNf≧2, whereas forNf=1 it is nonzero for the arbitrary high temperature.
119247942
Wilson loops @ 3-loops in special kinematics
A bstractWe obtain a compact expression for the octagon MHV amplitude/Wilson loop at 3 loops in planar $ \mathcal{N} = {4} $ SYM and in special 2d kinematics in terms of 7 unfixed coefficients. We do this by making use of the cyclic and parity symmetry of the amplitude/Wilson loop and its behaviour in the soft/collinear limits as well as in the leading term in the expansion away from this limit. We also make a natural and quite general assumption about the functional form of the result, namely that it should consist of weight 6 polylogarithms whose symbol consists of basic cross-ratios only (and not functions thereof). We also describe the uplift of this result to 10 points.
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).
14693268
Instantons in N=4 Sp(N) and SO(N) theories and the AdS / CFT correspondence
Following work on theories with SU(N) gauge groups, we perform a large-N saddle-point approximation of the measure for ADHM multi-instantons in N=4 supersymmetric gauge theories with symplectic or orthogonal gauge groups. For Sp(N) we find that a saddle-point only exists in the even instanton charge sector. For either Sp(N) or SO(N) the saddle-point solution parametrizes AdS_5 x RP^5, the dual supergravity geometry in the AdS/CFT correspondence for these theories. The instanton measure at large-N has the form of the partition function of ten-dimensional N=1 supersymmetric gauge theory with a unitary gauge group dimensionally reduced to zero dimensions.