Narrow Results

We report preliminary results of a search for substructure in quarks and leptons assuming a four-fermion contact interaction for dielectron pairs of large invariant mass. The search is based on dielectron data collected by the DØ detector in collisions at . The results agree well with predictions of the standard model and we obtain model-dependent lower limits at 95% confidence level on the compositeness scale of 3.6 to 9.1 TeV for different chiral models of the composite structure of quarks and electrons.

The structure of the hadron resonances attracts much attention, in association with the recent observations of various exotic hadrons which do not fit well in the conventional picture. These findings urge us to consider various new configurations such as the multiquark states and the hadronic molecules. However, it is a subtle problem to define a proper classification scheme for the hadron structure, and the nonzero decay width of the hadron resonances makes the analysis complicated. In this paper, we summarize the recent developments in the studies of the structure of the hadron resonances, focusing on the notion of the compositeness in terms of the hadronic degrees of freedom.

We study the composite electron production at the FCC-based three electron–proton colliders with the center-of-mass energies of 3.46, 10 and 31.6 TeV. For the signal process of $ep\to e^{\star }X\to e\gamma X$, the production cross-sections and decay widths of the excited electrons have been calculated. The differences of some kinematical quantities of the final state particles between the signal and background have been analyzed. For this purpose, transverse momentum and pseudorapidity distributions of electron and photon have been obtained and the kinematical cuts for discovery of the excited electrons have been assigned. We have finally determined the mass limits of excited electrons for observation and discovery by applying these cuts. It is shown that the mass limit for discovery obtained from the collider with $\sqrt{s}=31.6$ TeV (called PWFA-LC⊗FCC) is 22.3 TeV for the integrated luminosity $L_{\mathrm{\text{int}}}=10{\mathrm{\text{fb}}}^{-1}$.

Recent experimental observations of many unconventional hadronic states stimulate an interest in the structure of hadrons. While various internal configurations have been proposed, it is a subtle problem to identify the structure of hadron resonances in a model independent manner. Here we discuss the composite/elementary nature of hadrons using the field renormalization constant Z. In particular, we show that the magnitude of the effective range parameter r_e is related to the structure of s-wave near-threshold resonances.

Recent developments in hadron spectroscopy triggers the discussion on various exotic configurations beyond the simple three-quark state for baryons and quark-anti-quark pair for mesons. In particular, the states observed near a two-hadron threshold are often regarded as candidates of hadronic molecules, which are made of constituent hadrons and dynamically generated by the hadronic interactions. However, identification of the hadronic molecules involves several subtle difficulties which are often overlooked or underestimated. Here we summarize these subtleties and present a promising approach to distinguish the dynamically generated states from others using observable quantities.

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-P_T phenomena at HERA are reported. The searches use data samples of e^±p collisions with a centre-of-mass energy collected by the H1 and ZEUS experiments at HERA in the years 1994-2005 with integrated luminosities up to . Overall no significant deviations of the experimental observations from the Standard Model (SM) expectation are found.

Physical and methematical implications of nonlinear-supersymmetric general relativity theory(NLSUSYGR) are presented. They offer a new paradigm for the supersymmetric unification of space-time(Einstein general relativity theory(EGR)) and matter(the SM of particle physics), which gives new insight into the unsolved problems in EGR and SM.

Questions to discuss:

• If the SM with elementary Higgs field is completely confirmed with the discovery of a heavy scalar boson at LHC and Tevatron?
• Does the Higgs mass value of 126 GeV point to the need of new physics below the Planck scale?
• Do we need the next Higgs factory to solve problems with its identification?
• How can we distinguish extended Higgs sector from the standard one as well as from the composite Higgs?

Recent experimental observations of many unconventional hadronic states stimulate an interest in the structure of hadrons. While various internal configurations have been proposed, it is a subtle problem to identify the structure of hadron resonances in a model independent manner. Here we discuss the composite/elementary nature of hadrons using the field renormalization constant Z. In particular, we show that the magnitude of the effective range parameter r_e is related to the structure of s-wave near-threshold resonances.