117908598
Heavy Hadron Production in Hard Processes
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.
125850380
Multiple Hadron Production in Parton {QCD} Jets
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.
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.
8011091
Non-MHV tree amplitudes in gauge theory.
We show how all non-MHV tree-level amplitudes in 0 ? ? 4 gauge theories can be obtained directly from the known MHV amplitudes using the scalar graph approach of Cachazo, Svrcek and Witten. Generic amplitudes are given by sums of inequivalent scalar diagrams with MHV vertices. The novel feature of our method is that after the `Feynman rules' for scalar diagrams are used, together with a particular choice of the reference spinor, no further helicity-spinor algebra is required to convert the results into a numerically usable form. Expressions for all relevant individual diagrams are free of singularities at generic phase space points, and amplitudes are manifestly Lorentz- (and gauge-) invariant. To illustrate the method, we derive expressions for n-point amplitudes with three negative helicities carried by fermions and/or gluons. We also write down a supersymmetric expression based on Nair's supervertex which gives rise to all such amplitudes in 0 ? ? 4 gauge theories.
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.
119197756
Direct SUSY Searches at the LHC in the light of LEP Higgs bounds
A bstractIn this note we compare the latest 1.04 fb−1 LHC searches for squarks and gluinos from jets and missing transverse momentum (MET) with constraints arising from the LEP Higgs bound. For General Gauge Mediation models with moderate values of tan(β) we find that the zero-lepton MET searches of supersymmetry at the LHC are only starting to be competitive with the Higgs bounds from LEP. From this perspective and for such models, the SUSY searches at the LHC are still very much in the beginning.
120532941
Screening of multi-instanton corrections to anomalous processes in the standard model
Abstract We calculate the multi-instanton contribution to the logarithm of the cross-section for (B+L)-violating (anomalous) high-energy collisions in the next-to-leading order (in terms of ( E M sp ) 2 3 ) approximation. It is demonstrated that in this approximation there is no sign of “premature unitarization” of anomalous processes, i.e. there is no indication that multi-instanton contributions become of the same magnitude as the single-instanton contribution at energies where the single-instanton result is still exponentially suppressed.
120078928
Non-perturbative contribution to total cross sections in non-abelian gauge theories
Abstract We consider the instanton-induced contribution to the total cross section of vector boson scattering in the SU (2) gauge theory with and without Higgs mechanism. The exponential suppression of instanton-induced processes disappears asymptotically at energies for above the infrared cutoff for the instanton scale size, which is provided, in the Higgs (confinement) phase, by the vacuum expectation value (virtuality of the gluons). Instanton-induced processes may therefore be important in close-to-mass-shell gluon collisions. Our finding also suggests that electroweak baryon-and lepton-number violation with the associated production of many W-bosons may become important at very high energies.