Detecting an invisible Higgs boson at Fermilab Tevatron and CERN LHC

In this paper, we study the observability of an invisible Higgs boson at Fermilab Tevatron and CERN LHC through the production channel q \bar{q} \to Z H \to \ell^+\ell^-+ \ptmiss , where \ptmiss is reconstructed from the $\ell^+\ell^-$ with $\ell=e$ or $\mu$. A new strategy is proposed to eliminate the largest irreducible background, namely $q \bar{q} \to Z(\to \ell^+\ell^-) Z(\to \nu \bar\nu)$. This strategy utilizes the precise measurements of $q \bar{q} \to Z(\to \ell^+\ell^-) Z(\to \ell^+\ell^-)$. For $m_H=120$ GeV and with luminosity $30 fb^{-1}$ at Tevatron, a $5\sigma$ observation of the invisible Higgs boson is possible. For $m_H=114 \sim 140$ GeV with only $10 fb^{-1}$ luminosity at LHC, a discovery signal over $5\sigma$ can be achieved.Comment: 4 Revtex pages including 2 figure

Axion Searches

The strong CP problem and its resolution through the existence of an axion are briefly reviewed. The constraints on the axion from accelerator searches, from the evolution of red giants and from supernova SN1987a combine to require $m_a < 3 \cdot 10^{-3}$ eV, where $m_a$ is the axion mass. On the other hand, the constraint that axions do not overclose the universe implies m_a \gtwid 10^{-6} eV. If $m_a \sim 10^{-5}$ eV, axions contribute significantly to the cosmological energy density in the form of cold dark matter. Dark matter axions can be detected by resonant conversion to microwave photons in a cavity permeated by a static magnetic field and tuned to the axion mass. Experiments using this effect are described, as well as several other types of axion searches.Comment: 12 pages, 2 figures, based on talks at the TAUP99 Conference (Sept. 6-10, 1999, Paris, France) and at Adrianfest (Sept. 24-25, 1999, Rochester, NY

Higgs Searches

We present the status and prospects of Higgs searches at the Tevatron and the LHC. Results from the Tevatron are using up to 5/fb of data collected with the CDF and D0 detectors. The major contributing processes include associated production with vector bosons and gluon fusion. Improvements across the full mass range resulting from the larger data sets, improved analyses techniques and increased signal acceptance are discussed. Recent results exclude the SM Higgs boson in a mass range of 160 < mH < 170 GeV. Searches for the neutral MSSM Higgs boson in the region 90 < mA < 200 GeV exclude tanB values down to 30 for several benchmark scenarios.Comment: 6 pages, 13 figures, to be submitted in "XXIX Physics in Collision, Proceedings of the International Symposium in Kobe, Japan, August 30 - September 2, 2009

New particle searches

This review presents recent results on new particle searches achieved at Tevatron, Hera and LEP. After a brief outline of the searches on exotic particles, results on supersymmetric particles and Higgs bosons are detailed. Near future prospects are also given.Comment: 25 pages, 11 postscript figures, typo corrections. To appear in Proceedings of XIX Lepton-Photon Symposium, Stanford, August 199

Searches at HERA

Searches for physics beyond the Standard Model have been performed in high-energy $e^{\pm}p$ collisions at HERA. No significant deviation from the Standard Model has been observed while searching for contact interactions, extra dimensions, leptoquarks, R-parity violating squarks and excited fermions. Exclusion limits have been inferred which extend or complement bounds from other colliders. The H1 collaboration has observed a puzzling excess of events with an high $P_t$ isolated lepton and missing transverse momentum, and interpretation as flavour changing neutral currents has been explored.Comment: 7 pages, 6 figures, contribution to the Lake Louise Winter Institut

RooStats for Searches

The RooStats toolkit, which is distributed with the ROOT software package, provides a large collection of software tools that implement statistical methods commonly used by the High Energy Physics community. The toolkit is based on RooFit, a high-level data analysis modeling package that implements various methods of statistical data analysis. RooStats enforces a clear mapping of statistical concepts to C++ classes and methods and emphasizes the ability to easily combine analyses within and across experiments. We present an overview of the RooStats toolkit, describe some of the methods used for hypothesis testing and estimation of confidence intervals and finally discuss some of the latest developments.Comment: Contributed to "PHYSTAT 2011 Workshop on Statistical Issues Related to Discovery Claims in Search Experiments and Unfolding