On the Value of R=\Gamma_h/\Gamma_l at LEP

We show that the present experimental LEP average R=\Gamma_h/\Gamma_l= 20.795 +- 0.040 is not unambiguous due to the presence of substantial systematic effects which cannot be interpreted within gaussian statistics. We find by Montecarlo simulation that the C.L. of the original LEP sample is only 3.8 \cdot 10^{-4}. We suggest that a reliable extimate of the true R-value is 20.60< R < 20.98 which produces only a very poor determination of the strong coupling constant at the Z mass scale, 0.10< \alpha_s(M_z)< 0.15.Comment: 4 pages, LaTeX; Postscript file, compressed and uuencoded, availabl

Can the sneutrino be the lightest supersymmetric particle ?

Within the framework of the constrained Minimal Supersymmetric extension of the Standard Model we show that recent LEP I limits on the invisible Z width exclude the possibility that the lightest sparticle is the sneutrino

Detection of New Heavy Charged Gauge Bosons in the Muon plus Neutrino Channel

This note presents a feasibility study of the search for a new heavy charged gauge boson with the CMS detector at the Large Hadron Collider LHC. The model assumes the existence of a heavy carbon copy of the Standard Model W (Reference Model by Altarelli) generically denoted as Wprime. Such a boson has been investigated in the decay channel Wprime --> \mu \nu using the full detector simulation including minimum bias events (pile-up) according to the expected first years of luminosity. All relevant Standard Model backgrounds have been considered. Such a new boson is expected to be discovered, if existant, with a mass of 0.1-4.6 TeV for an integrated luminosity of 10 fb^-1. The range can be expanded to 6.1 TeV with an integrated luminosity of 300 fb^-1. If no signs for a Wprime boson appear 95% CL exclusion limits of 4.7 TeV and 6.2 TeV can be set respectively

Simulation of Cosmic Muons and Comparison with Data from the Cosmic Challenge using Drift Tube Chambers

The reconstruction of cosmic muons is important for the commissioning phase and alignment of the Compact Muon Solenoid experiment (CMS), in particular during the early phases of operation with physics collisions. In this context the Magnet Test/Cosmic Challenge (MTCC) with its comprehensive cosmic data taking periods including the presence of the magnetic field has been like a dress rehearsal of detector hardware and software for the upcoming startup of the CMS detector. In addition to data taking also the comparison with simulated events is a crucial part of physics analyses. This study introduces a new cosmic muon generator, CMSCGEN, and it presents its validation by comparing with data from MTCC. As an example results from a reconstruction study using the barrel Muon System are shown, comparing data and Monte Carlo prediction at the level of single chambers up to reconstructed tracks including momentum measurements

Virtual Supersymmetric Corrections in e^+e^- Annihilation

Depending on their masses, Supersymmetric particles can affect various measurements in Z decay. Among these are the total width (or consequent extracted value of $\alpha_s$), enhancement or suppression of various flavors, and left-right and forward-backward asymmetries. The latter depend on squark mass splittings and are, therefore, a possible test of the Supergravity related predictions. We calculate leading order corrections for these quantities considering in particular the case of light photino and gluino where the SUSY effects are enhanced. In this limit the effect on $\alpha_s$ is appreciable, the effect on $R_b$ is small, and the effect on the asymmetries is extremely small.Comment: 11 pages, LaTeX, 3 figures, revised, a reference adde

Study of Pair-Produced Doubly Charged Higgs Bosons with a Four Muon Final State at the CMS Detector

An analysis of the discovery potential of pairproduced doubly charged Higgs bosons at the CMS detector is presented in this note. Investigated are doubly charged Higgs bosons pairproduced by the Drell-Yan process. A branching ratio of 100% into muon pairs is assumed. The pure muonic decay channel yields a clear signal which is almost free of background. Doubly charged Higgs bosons with masses in the range 100 to 800 GeV are studied, for a low luminosity scenario of L = 2x10^33cm^-2s^-1. The full detector simulation is used. Doubly charged Higgs bosons in this production and decay channel with mass m(H^pm pm) le 650~GeV are expected to be observable at CMS with a significance exceeding 5 sigma at 1 fb^-1 of integrated luminosity. If no signal will be detected for this integrated luminosity, the existence of a doubly charged Higgs Boson with m((H^pm pm) le 760~GeV can be excluded with 95% Confidence level. This exceeds the current exclusion limit for this channel mH^pm pm) le 136~GeV, set by CDF at Tevatron Run II, by 624~GeV

The τ\tau-W Coupling

We interpret the existing experimental knowledge on $\tau$ decays in terms of the vector and axial vector couplings to the W boson, $V_{\tau}$ and $A_{\tau}$. We deduce $V_{\tau} = 1.00 \pm 0.09$ and $A_{\tau} = 1.00 \pm 0.09$ in agreement with the Standard Model predictions of $1$

Biological implications of high-energy cosmic ray induced muon flux in the extragalactic shock model

A ~ 62 My periodicity in fossil biodiversity has been observed in independent studies of paleontology databases over ~0.5Gy. The period and phase of this biodiversity cycle coincides with the oscillation of our solar system normal to the galactic disk with an amplitude ~70 parsecs and a period ~64 My. Our Galaxy is falling toward the Virgo cluster, forming a galactic shock at the north end of our galaxy due to this motion, capable of accelerating particles and exposing our galaxy's northern side to a higher flux of cosmic rays. These high-energy particles strike the Earth's atmosphere initiating extensive air showers, ionizing the atmosphere by producing charged secondary particles. Secondary particles such as muons produced as a result of nuclear interactions are able to reach the ground and enhance the biological radiation dose. Using a Monte Carlo simulation package CORSIKA, we compute the biological dose resulting from enhanced muon exposure from cosmic rays and discuss their implications for terrestrial biodiversity variations.Comment: Accepted for publication in Geophysical Research Letter