57 research outputs found
Higgs Self-Coupling in gamma-gamma Collisions
To establish the Higgs mechanism experimentally, one has to determine the
Higgs self-interaction potential responsible for the electroweak symmetry
breaking. This requires a measurement of the trilinear and quadrilinear
self-couplings of the Higgs particle, as predicted by the Standard Model (SM).
We propose to measure the trilinear Higgs self-coupling in gamma-gamma
collisions just above the kinematic threshold E_thr = 2M_H, where M_H is the
Higgs mass. Our calculation reveals that the sensitivity of the cross-section
sigma(gamma gamma -> HH) to the Higgs self-coupling is maximal near the 2M_H
threshold for M_H = 115-150 GeV, and is larger than the sensitivities of
sigma(e+e- -> ZHH) and sigma(e+e- -> nu nu HH) to this coupling for 2E_e < 700
GeV. We envisage to (a) study gamma gamma -> H by constructing an X-band e-e-
linac and a terawatt laser system in order to produce Compton-scattered
gamma-ray beams for a 160-GeV photon collider (2E_e = 200 GeV); (b) add a
positron source and repeat all measurements done at LEP and SLC with much
better precision; and (c) subsequently install 70-MeV/m rf cavities in order to
study e+e- -> H+Z, e+e- -> tt and gamma gamma -> H+H at 2E_e = 350 GeV. The
total length of the linac would be about 7 km.Comment: 14 pages, 5 figures, LaTeX. Submitted to Phys. Rev.
Charmonium production at neutrino factories
At existing and planned neutrino factories (high energy and high intensity
neutrino beam facilities) precision studies of QCD in neutrino-nucleon
interactions are a realistic opportunity. We investigate charmonium production
in fixed target neutrino experiments. We find that production in
neutrino-nucleon collision is dominated by the color octet NRQCD matrix
element in a neutral current process, which is not accessible in photo or
leptoproduction. Neutrino experiments at a future Muon Collider will acquire
sufficient event rate to accurately measure color octet matrix element
contributions. The currently running high energy neutrino experiments, NOMAD
and NuTeV could also observe several such events.Comment: 13 pages Latex, with five embedded eps figures. Cosmetic fixups in
the figures, otherwise unchange
Higher Twist, Scaling, and Effective for Lepton Scattering in the Few GeV Region
We use a new scaling variable , and add low modifications to
GRV98 leading order parton distribution functions such that they can be used to
model electron, muon and neutrino inelastic scattering cross sections (and also
photoproduction) at both very low and high energies.Comment: 6 pages, 3 figures. To be published in J. Phys. G (Conf. Proceedings)
based on two talks by Arie Bodek at the NuFact conference, Imperial
College, London, England, July 200
Observation of an Anomalous Number of Dimuon Events in a High Energy Neutrino Beam
A search for long-lived neutral particles (N^0's) with masses above 2.2
GeV/c^2 that decay into at least one muon has been performed using an
instrumented decay channel at the NuTeV experiment at Fermilab. Data were
examined for particles decaying into the final states mu mu, mu e, and mu pi.
Three mu mu events were observed over an expected Standard Model background of
0.069 +/- 0.010 events; no events were observed in the other modes.Comment: 5 pages, 3 figures, Submitted to Phys. Rev. Let
The Potential for Neutrino Physics at Muon Colliders and Dedicated High Current Muon Storage Rings
Conceptual design studies are underway for muon colliders and other
high-current muon storage rings that have the potential to become the first
true ``neutrino factories''. Muon decays in long straight sections of the
storage rings would produce precisely characterized beams of electron and muon
type neutrinos of unprecedented intensity. This article reviews the prospects
for these facilities to greatly extend our capabilities for neutrino
experiments, largely emphasizing the physics of neutrino interactions.Comment: 107 pages, 16 figures, to be published in Physics Report
Search for the Lepton Number Violating Process nu_mu-bar e^- -> mu^- nu_e-bar
The NuTeV experiment at Fermilab has used a sign-selected neutrino beam to
perform a search for the lepton number violating process nu_mu-bar e^- -> mu^-
nu_e-bar, and to measure the cross-section of the Standard Model inverse muon
decay process nu_mu e^- -> mu^- nu_e. NuTeV measures the inverse muon decay
asymptotic cross-section sigma/E to be 13.8 +/- 1.2 +/- 1.4 x 10^-42 cm^2/GeV.
The experiment also observes no evidence for lepton number violation and places
one of the most restrictive limits on the LNV/IMD cross-section ratio at < 1.7%
at 90% C.L. for V-A couplings and < 0.6% for scalar couplings.Comment: 4 pages, 4 figures, 2 tables. Submitted to Physics Review Letter
Methods to Determine Neutrino Flux at Low Energies:Investigation of the Low Method
We investigate the "low-" method (developed by the CCFR/NUTEV
collaborations) to determine the neutrino flux in a wide band neutrino beam at
very low energies, a region of interest to neutrino oscillations experiments.
Events with low hadronic final state energy (of 1, 2 and 5 GeV)
were used by the MINOS collaboration to determine the neutrino flux in their
measurements of neutrino () and antineutrino (\nub_\mu) total cross
sections. The lowest energy for which the method was used in MINOS is
3.5 GeV, and the lowest \nub_\mu energy is 6 GeV. At these energies, the
cross sections are dominated by inelastic processes. We investigate the
application of the method to determine the neutrino flux for ,
\nub_\mu energies as low as 0.7 GeV where the cross sections are dominated by
quasielastic scattering and (1232) resonance production. We find that
the method can be extended to low energies by using values of 0.25
and 0.50 GeV, which is feasible in fully active neutrino detectors such as
MINERvA.Comment: 25 pages, 32 figures, to be published in European Physics Journal
A Measurement of the Cross Section in Two-Photon Processes
We have measured the inclusive production cross section in a
two-photon collision at the TRISTAN collider. The mean of
the collider was 57.16 GeV and the integrated luminosity was 150 . The
differential cross section () was obtained in the
range between 1.6 and 6.6 GeV and compared with theoretical predictions, such
as those involving direct and resolved photon processes.Comment: 8 pages, Latex format (article), figures corrected, published in
Phys. Rev. D 50 (1994) 187
Measurement of the forward-backward asymmetries for charm- and bottom-quark pair productions at =58GeV with electron tagging
We have measured, with electron tagging, the forward-backward asymmetries of
charm- and bottom-quark pair productions at =58.01GeV, based on
23,783 hadronic events selected from a data sample of 197pb taken with
the TOPAZ detector at TRISTAN. The measured forward-backward asymmetries are
and , which are consistent with the standard model
predictions.Comment: 19 pages, Latex format (article), 5 figures included. to be published
in Phys. Lett.
Evidence for Diffractive Charm Production in nu_mu Fe and nubar_mu Fe Scattering at the Tevatron
We present evidence for the diffractive processes nu_mu Fe -> mu^- D_s^+
(D_s^*+) Fe and nubar_mu Fe -> mu^+ D_s^- (D_s^*-) Fe using the Fermilab SSQT
neutrino beam and the Lab E neutrino detector. We observe the neutrino trident
reactions nu_mu Fe -> nu_mu mu^- mu^+ Fe and nubar_mu Fe -> nubar_mu mu^+ mu^-
Fe at rates consistent with Standard Model expectations. We see no evidence for
neutral-current production of J/psi via either diffractive or deep inelastic
scattering mechanisms.Comment: 13 pages, submitted to Phys. Rev. D, FERMILAB-Pub-99/269-
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