20,416 research outputs found

    Electroweak precision measurements and collider probes of the Standard Model with large extra dimensions

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    The elementary particles of the Standard Model may live in more than 3+1 dimensions. We study the consequences of large compactified dimensions on scattering and decay observables at high-energy colliders. Our analysis includes global fits to electroweak precision data, indirect tests at high-energy electron-positron colliders (LEP2 and NLC), and direct probes of the Kaluza-Klein resonances at hadron colliders (Tevatron and LHC). The present limits depend sensitively on the Higgs sector, both the mass of the Higgs boson and how many dimensions it feels. If the Higgs boson is trapped on a 3+1 dimensional wall with the fermions, large Higgs masses (up to 500 GeV) and relatively light Kaluza-Klein mass scales (less than 4 TeV) can provide a good fit to precision data. That is, a light Higgs boson is not necessary to fit the electroweak precision data, as it is in the Standard Model. If the Higgs boson propagates in higher dimensions, precision data prefer a light Higgs boson (less than 260 GeV), and a higher compactification scale (greater than 3.8 TeV). Future colliders can probe much larger scales. For example, a 1.5 TeV electron-positron linear collider can indirectly discover Kaluza-Klein excitations up to 31 TeV if 500 fb^-1 integrated luminosity is obtained.Comment: 29 pages, LaTe

    Surveyor lunar touchdown stability study Final report, Jul. 1965 - Jul. 1966

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    Dynamic analysis and computer simulation of Surveyor lunar landing stabilit

    Editorial

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    PeV-Scale Supersymmetry

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    Although supersymmetry has not been seen directly by experiment, there are powerful physics reasons to suspect that it should be an ingredient of nature and that superpartner masses should be somewhat near the weak scale. I present an argument that if we dismiss our ordinary intuition of finetuning, and focus entirely on more concrete physics issues, the PeV scale might be the best place for supersymmetry. PeV-scale supersymmetry admits gauge coupling unification, predicts a Higgs mass between 125 GeV and 155 GeV, and generally disallows flavor changing neutral currents and CP violating effects in conflict with current experiment. The PeV scale is motivated independently by dark matter and neutrino mass considerations.Comment: 5 RevTex page

    Tributes to Professor Robert Berkley Harper

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    In 1977, I began teaching at The University of Pittsburgh Law School and in short order one of my closest friends during my tenure there was Professor Robert “Bob” Harper. I wondered when I was hired whether I was selected because I looked strikingly similar to Bob, and perhaps the faculty thought my favoring Professor Harper would make my assimilation into the law school faculty that much easier. Students constantly called me Professor Harper and, indeed, many on the faculty called me Bob for several years; I never bothered to correct them. I thought if they paid that little attention to detail in law school, I would just let them go through life missing some of the finer points their education, and life for that matter, has to offer

    Resource management implications of ERTS-1 data to Ohio

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    Initial experimental analysis of ERTS-1 imagery has demonstrated that remote sensing from space is a means of delineating and inventorying Ohio's strip-mined areas, detecting power plant smoke plumes, and proving the data necessary for periodically compiling land use maps for the entire state. The nature and extent of these problems throughout Ohio, how ERTS data can contribute to their solution, and estimates of the long term significance of these initial findings to overall resource management interests in Ohio are summarized

    Temporal frequency of radio emissions for the April 25, 1984 flare

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    The National Geophysical Data Center archives data of the solar-terrestrial environment. The USAF Radio Solar Telescope Network (RSTN) data allow performance of time series analysis to determine temporal oscillations as low as three seconds. The X13/3B flare which erupted in region 4474 (S12E43) on the 24 to 25 of April 1984, was selected. The soft X-rays, 1 to 8 A, remained above X-levels for 50 minutes and the radio emissions measured at Learmonth Solar Observatory reached a maximum of 3.15 x 10 to the 5th power SFUs at 410 MHz at 0000UT. A power spectral analysis of the fixed frequency RSTN data from Learmonth shows possible quasi-periodic fluctuations in the range two to ten seconds. Repetition rates or quasi-periodicities, in the case of the power spectral analysis, generally showed the same trends as the average solar radio flux at 245 and 8800 MHz. The quasi-periodicities at 1415 MHz showed no such trends
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