118466202
Central Diffractive Processes at the Tevatron, RHIC and LHC
Central exclusive production (CEP) processes in high‐energy hadron collisions offer a very promising framework for studying both novel aspects of QCD and new physics signals. We report on the results of a theoretical study of the CEP of heavy quarkonia (χ and η) at the Tevatron, RHIC and LHC (see for details [1]–[3]). These processes provide important information on the physics of bound states and can probe the current ideas and methods of QCD, such as effective field theories and lattice QCD.
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
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.
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.
56217615
New constraints on gauge mediation and beyond from LHC SUSY searches at 7 TeV
The first results from the LHC on jets plus missing energy provide powerful new data to test SUSY models. Initial theoretical interpretations of these data have concentrated on gravity mediation, usually the CMSSM and its variations. In this paper we confront a large class of gauge mediation models with these new data. More precisely we consider models of pure general gauge mediation (pure GGM) and confront them with the recent experimental results of the ATLAS collaboration. We use Herwig++ and RIVET, incorporating the full set of experimental cuts, to calculate the signal rates and compare them to the data. Although based on only 35pb−1 of integrated luminosity, we show that these new data probe and exclude a portion of previously allowed parameter space of GGM. In addition we investigate the viability of standard SUSY benchmark points, including the Snowmass, CMS and ATLAS sets which encompass other mediation scenarios such as gravity, anomaly and gaugino mediation.
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.
62799412
Constraining Dark Sectors at Colliders: Beyond the Effective Theory Approach
We outline and investigate a set of benchmark simplified models with the aim of providing a minimal simple framework for an interpretation of the existing and forthcoming searches of dark matter particles at the LHC. The simplified models we consider provide microscopic QFT descriptions of interactions between the Standard Model partons and the dark sector particles mediated by the four basic types of messenger fields: scalar, pseudoscalar, vector and axial-vector. Our benchmark models are characterized by four to five parameters, including the mediator mass and width, the dark matter mass and the effective coupling(s). In the gluon fusion production channel we resolve the top quark in the loop and compute full top-mass effects for scalar and pseudoscalar messengers. We show the LHC limits and reach at 8 and 14 TeV for models with all four messenger types. We also outline the complementarity of direct detection, indirect detection and LHC bounds for dark matter searches. Finally, we investigate the effects which arise from extending the simplified model to include potential new physics contributions in production. Using the scalar mediator as an example, we study the impact of heavy new physics loops which interfere with the top-mediated loops. Our computations are performed within the mcfm framework, and we provide fully flexible public Monte Carlo implementation.
14263791
Noncommutative Standard Modelling
We present a noncommutative gauge theory that has the ordinary Standard Model as its low-energy limit. The model is based on the gauge group U(4) × U(3) × U(2) and is constructed to satisfy the key requirements imposed by noncommutativity: the UV/IR mixing effects, restrictions on representations and charges of matter fields, and the cancellation of noncommutative gauge anomalies. At energies well below the noncommutative mass scale our model flows to the commutative Standard Model plus additional free U(1) degrees of freedom which are decoupled due to the UV/IR mixing. Our model also predicts the values of the hypercharges of the Standard Model fields.
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.