Related papers: Zooming-in on Instantons at HERA
With the knowledge of diffractive parton densities extracted from HERA data, we discuss the observation of exclusive events using the dijet mass fraction as measured by the CDF collaboration at the Tevatron. In particular the impact of the…
A contact four-fermion interaction between light quarks and electrons has been evoked as a possible explanation for the excess of events observed by HERA at high-$Q^2$. We explore the 1-loop effects of such interaction in $\Gamma(Z^0 \to…
I review the theoretical status of hadronization corrections to hadronic event observables and discuss their impact on the determination of $\alpha_s$.
I present a concise review of the possible evidence for new physics at HERA and of the recent work towards a theoretical interpretation of the signal. It is not clear yet if the excess observed at large Q^2 is a resonance or a continuum…
Recent results for direct searches for physics beyond the Standard Model are reviewed. The results include Tevatron II data up to 1.2 fb-1 and HERA results up to 350 pb-1. Searches for Supersymmetry, for compositeness and for large extra…
The present status of Unified Theories is summarized with special emphasis on their possible experimental tests. Outline: i) Unification of couplings; ii) Where can a positive signal come from? iii) HERA anomaly and Unification; iv) Recent…
The excess in high-Q^2 events at HERA is introduced and possible explanations within the framework of R-parity violating supersymmetry are discussed.
I investigate the theoretical uncertainties on the predictions for the longitudinal structure function. I compare the predictions using fixed-order perturbative QCD, higher twist corrections, small-x resummations and the dipole picture. I…
The latest results from the H1 and ZEUS collaborations which challenge the QCD description of high energy $ep$ collisions are presented. Data from HERA continue to provide precision measurements and are compared to the latest theoretical…
A search for excited neutrinos, the analysis of multi-lepton final states, a search for doubly charged Higgs production and a general search for high-Pt phenomena at HERA are reported. The searches use data samples of ep collisions with a…
Recent progresses of the proton structure measurements and determination of parton distribution functions by $ep$ collisions at HERA are introduced.
Data from H1 and ZEUS on the structure and the quark and gluon densities of the proton are discussed. A brief excursion is made into the field of inclusive diffraction by deep inelastic scattering. The comparison of e- p and e+ p scattering…
We review recent results on diffraction at HERA and discuss their interpretation in the perturbative and non-perturbative regimes.
Attempts to understand the recent observation of an excess of events in the neutral and charged current channels at high$-Q^2$ at HERA has provided an excellent example of how experiments at both low and high energies can be used to…
The aim of this review is to demonstrate that there exists a coherent picture of strong interactions, based on instantons. Starting from the first principles of QCD - via the microscopic mechanism of spontaneous chiral symmetry breaking -…
The search for events containing isolated leptons and missing transverse momentum produced in ep collisions is performed individually and in a common phase space with the H1 and ZEUS detectors at HERA. The combined H1 and ZEUS data sample…
QCD instantons are arguably the best motivated yet unobserved nonperturbative effects predicted by the Standard Model. A discovery and detailed study of instanton-generated processes at colliders would provide a new window into the…
We present our results for inclusive instanton-induced cross-sections in deep-inelastic scattering, paying in particular attention to the residual renormalization-scale dependencies. A ``fiducial'' kinematical region in the relevant Bjorken…
A recent analysis of prompt-photon events in ZEUS has led to a new determination of the effective transverse parton momentum in the proton. The observation of deeply virtual Compton scattering by ZEUS and H1, including a first measurement…
Signals of QCD instanton induced processes are searched for in deep-inelastic ep scattering at HERA in a kinematic region defined by the Bjorken scaling variables x>0.001, 0.1<y<0.6 and polar angle of the scattered positron >156 degrees.…