117156090
On the profiles of jets initiated by light and heavy quarks
We review some recent results in applications of the analytical perturbative technique to the description of particle distributions in QCD jets. Gluon emission in top production is briefly discussed.
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.
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
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.
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.
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.
118108888
The valley method and its applications to the instanton-induced phenomena in non-Abelian gauge theories
6234472
Fermion number violation in the background of a gauge field in Minkowski space
Abstract Anomalous fermion number violation is studied in the background of a pure SU(2) gauge field in Minkowski space using the method of N. Christ. It is demonstrated that the chiral fermion number is violated by at most an integer amount. Then the method is applied for a spherically symmetric Minkowski space classical gauge field in the background. These classical gauge fields are finite energy solutions to pure SU(2) equations of motion with in general non-integer topological charge. We show that in the classical background which during a finite time-interval matches such solutions the fermion number violation is integer and non-zero. In particular, we calculate the violation of the fermiion number in the presence of Luscher-Schechter solutions. The meaning of the anomaly equation and applications to QCD and electroweak theory are briefly discussed. We also comment on the relation of the results of this paper to the previous work.
14703262
Supersymmetry and the multi-instanton measure
Abstract We propose explicit formulae for the integration measure on the moduli space of charge- n ADHM multi-instantons in N = 1 and N = 2 supersymmetric gauge theories. The form of this measure is fixed by its (super) symmetries as well as the physical requirement of clustering in the limit of large spacetime separation between instantons. We test our proposals against known expressions for n ⩽ 2. Knowledge of the measure for all n allows us to revisit, and strengthen, earlier N = 2 results, chiefly: (1) For any number of flavors N F , we provide a closed formula for F n , the n -instanton contribution to the Seiberg-Witten propotential, as a finite-dimensional collective coordinate integral. This amounts to a solution, in quadratures, of the Seiberg-Witten models, without appeal to electric-magnetic duality. (2) In the conformal case N F = 4, this means reducing to quadratures the previously unknown finite renormalization that relates the microscopic and effective coupling constants, τ micro and τ eff . (3) Similar expressions are given for the 4-derivative/8-fermion term in the gradient expansion of N = 2 supersymmetric QCD.
16492553
Magnetic mixing — electric minicharges from magnetic monopoles
Many extensions of the Standard Model require the existence of a ``hidden'' sector. We consider settings where the hidden sector in the infrared contains a U(1) gauge factor with magnetic monopoles, for instance 't Hooft-Polyakov monopoles of an underlying non-abelian gauge group. In the presence of CP violation these monopoles acquire an electric charge in the hidden sector due to the Witten effect. We show that quite generally they also acquire (small) electric charges under the visible electromagnetic gauge group. This is a result of ``magnetic mixing'' which, as we show, often arises as a natural partner of kinetic mixing. Both kinetic and magnetic mixing are naturally induced radiatively even if the low-energy U(1)s arise from a single non-abelian gauge group. We argue that the hidden sector monopoles can be light and their electric minicharges could thus be testable in current and near future low-energy experiments.