95691104
Preparing crystals for channeling experiments at high energies
Abstract On the basis of the experience of silicon crystal preparation for two Fermilab experiments on particle channeling (E761 and E853) the requirements for the crystal perfection for high energy physics experiments are discussed. Techniques which provide the cutting, orientation with high accuracy and test the quality of the initial and completed crystals are presented.
125857609
A Search for the production of prompt neutrinos in high energy proton nucleus collisions
116956262
Design of a crystal extraction facility in the east utility straight
Parasitic extraction of a small fraction of the 20-TeV circulating beam of the Superconducting Super Collider can be done using a bent crystal situated in the halo of the orbiting beam. The authors present a design of a crystal extraction system that is compatible with current plans for momentum scraping in the east utility straight. The only modification to the collider tunnel is the addition of a 160-m-long alcove in the east utility straight to mate the extracted beam line microtunnel with the collider tunnel. No other changes to the east utility straight tunnel are needed.
38493149
Position Determination of High Energy Photons in Lead Glass
Two 25 element SF5 lead glass Cerenkov counter arrays have been used in the study of photon and ¿° production in pN collisions at Fermilab. The method used to identify shower patterns, and the determination of the position of the photon in the lead glass arrays in the energy range 2-32 GeV is presented. The method enables the spatial position of photons in this energy range width to be measured with a resolution of ¿ = 0.25 inches.
120121929
Characteristics of the radiation damage seen in the silicon microstrip detector of Fermilab experiment E771
The central region of the silicon microstrip detector used in Fermilab experiment E771 was subjected to a peak fluence of 9.5 × 1013 p/cm2 induced by 800 GeV protons over a two-month period. Fourteen 300 μm thick planes manufactured by Micron Semiconductor were operated at bias voltages ranging from 84 to 109 V. Analysis of data from low intensity beam triggers taken near the end of the run shows that the mean pulse height from our amplifiers began to decline at a fluence of approximately 2 × 1013 p/cm2 and fell to near zero by 6 × 1013 p/cm2. We show that the use of fast amplifiers contributed to this early loss of signal.
124276644
Cross sections for the reactions anti-p + p ---> pi-plus + pi-minus and k-plus + k-minus near 2 gev/c
55399019
Massive spin-2 states as the origin of the top quark forward-backward asymmetry
We show that the anomalously large top quark forward-backward asymmetry observed by CDF and DØ can naturally be accommodated in models with flavor-violating couplings of a new massive spin-2 state to quarks. Regardless of its origin, the lowest-order couplings of a spin-2 boson to fermions are analogous to the coupling of the graviton to energy/momentum, leading to strong sensitivity of the effects associated with its virtual exchange to the energy scales at hand. Precisely due to this fact, the observed dependence of the asymmetry on the $ t\overline t $ invariant mass fits nicely into the proposed framework. In particular, we find a vast parameter space which can lead to the central value for the observed forward-backward asymmetry in the high mass bin.
86860651
Theoretical constraints on additional Higgs bosons in light of the 126 GeV Higgs
A bstractWe present a sum rule for Higgs fields in general representations under SU(2)L × U(1)Y that follows from the connection between the Higgs couplings and the mechanism that gives the electroweak bosons their masses, and at the same time restricts these couplings. Sum rules that follow from perturbative unitarity will require us to include singly and doubly charged Higgses in our analysis. We examine the consequences of these sum rules for Higgs phenomenology in both model independent and model specific ways. The relation between our sum rules and other works, based on dispersion relations, is also clarified.
56563443
On Limit Cycles in Supersymmetric Theories
Abstract Contrary to popular belief conformality does not require zero beta functions. This follows from the work of Jack and Osborn, and examples in non-supersymmetric theories were recently found by some of us. In this Letter we show that such examples are absent in unitary N = 1 supersymmetric four-dimensional field theories. More specifically, we show to all orders in perturbation theory that the beta-function vector field of such theories does not admit limit cycles. A corollary of our result is that unitary N = 1 supersymmetric four-dimensional theories cannot be superscale-invariant without being superconformal.
89614484
Searching for new physics in the three-body decays of the Higgs-like particle
A bstractWe show that the three-body decays of the resonance recently discovered at the LHC are potentially sensitive to effects of new physics. Even if the fully integrated partial decay widths are consistent with the minimal Standard Model there is information that is lost upon integration, which can be uncovered in the differential decay widths. Concentrating on the decay h → Zℓ$ \overline{\ell} $, we identify the regions in the three-body phase space in which these effects become especially pronounced and could be detected in future experiments.
122070076
Muon trigger electronics for hadron collider experiments
Abstract Trigger electronics designed and constructed for the SDC muon system are described briefly and results of beam tests carried out at KEK are presented. The implementation is based on custom VLSI designs in 1.2 μm CMOS. The performance characteristics of the circuits were measured and confirmed to meet specifications. Designs based on this approach are applicable to future collider experiments.