106 research outputs found
Uncertainties in Atmospheric Muon-Neutrino Fluxes Arising from Cosmic-Ray Primaries
We present an updated calculation of the uncertainties on the atmospheric
muon-neutrino flux arising from cosmic-ray primaries. For the first time, we
include recent measurements of the cosmic-ray primaries collected since 2005.
We apply a statistical technique that allows the determination of correlations
between the parameters of the GSHL primary-flux parametrisation and the
incorporation of these correlations into the uncertainty on the muon-neutrino
flux. We obtain an uncertainty related to the primary cosmic rays of around
, depending on energy, which is about a factor of two smaller
than the previously determined uncertainty. The hadron production uncertainty
is added in quadrature to obtain the total uncertainty on the neutrino flux,
which is reduced by . To take into account an unexpected hardening
of the spectrum of primaries above energies of observed in
recent measurements, we propose an alternative parametrisation and discuss its
impact on the neutrino flux uncertainties
Light Higgs Production at a Photon Collider
We present a preliminary study of the production of a light Higgs boson with
a mass between 120 and 160 GeV in photon-photon collisions at a Compton
collider. The event generator for the backgrounds to a Higgs signal due to
bbbar and ccbar heavy quark pair production in polarized Gamma-Gamma collisions
is based on a complete next-to-leading order (NLO) perturbative QCD
calculation. For J_z=0 the large double-logarithmic corrections up to four
loops are also included. It is shown that the two-photon width of the Higgs
boson can be measured with high statistical accuracy of about 2-10% for
integrated Gamma-Gamma luminosity in the hard part of the spectrum of 43 fb-1.
From this result the total Higgs boson width can be derived in a model
independent way.Comment: 12 pages, submitted to International Workshop on High Energy Photon
Colliders, June 14 - 17, 2000, DESY Hamburg, German
Jet and hadron production in photon-photon collisions
Di-jet and inclusive charged hadron production cross-sections measured in
photon-photon collisions by OPAL are compared to NLO pQCD calculations. Jet
shapes measured in photon-photon scattering by OPAL, in deep-inelastic ep
scattering by H1 and in photon-proton scattering by ZEUS are shown to be
consistent in similar kinematic ranges. New results from TOPAZ on prompt photon
production in photon-photon interactions are presented.Comment: 4 pages, submitted to Proceedings of DIS99, DESY-Zeuthen, Germany,
April 199
Direct comparison of sterile neutrino constraints from cosmological data, disappearance data and appearance data in a model
We present a quantitative, direct comparison of constraints on sterile
neutrinos derived from neutrino oscillation experiments and from Planck data,
interpreted assuming standard cosmological evolution. We extend a model,
which is used to compare exclusions contours at the 95% CL derived from Planck
data to those from -disappearance measurements, to a model. This
allows us to compare the Planck constraints with those obtained through
appearance searches, which are sensitive to more
than one active-sterile mixing angle. We find that the cosmological data fully
exclude the allowed regions published by the LSND, MiniBooNE and Neutrino-4
collaborations, and those from the gallium and rector anomalies, at the 95% CL.
Compared to the exclusion regions from the Daya Bay -disappearance
search, the Planck data are more strongly excluding above and
, with the Daya Bay
exclusion being stronger below these values. Compared to the combined Daya
Bay/Bugey/MINOS exclusion region on appearance,
the Planck data is more strongly excluding above , with the exclusion strengths of the Planck
data and the Daya Bay/Bugey/MINOS combination becoming comparable below this
value.Comment: 9 pages, 4 figures, accepted by Eur. Phys. J.
Direct comparison of sterile neutrino constraints from cosmological data, Îœ e disappearance data and Îœ ÎŒ â Îœ e appearance data in a 3 + 1 model
From Springer Nature via Jisc Publications RouterHistory: received 2020-02-22, registration 2020-07-03, accepted 2020-07-03, pub-print 2020-08, pub-electronic 2020-08-19, online 2020-08-19Publication status: PublishedFunder: H2020 Marie Sklodowska-Curie Actions; doi: http://dx.doi.org/10.13039/100010665; Grant(s): 752309Abstract: We present a quantitative, direct comparison of constraints on sterile neutrinos derived from neutrino oscillation experiments and from Planck data, interpreted assuming standard cosmological evolution. We extend a 1+1 model, which is used to compare exclusion contours at the 95% Cl derived from Planck data to those from Îœe-disappearance measurements, to a 3+1 model. This allows us to compare the Planck constraints with those obtained through ΜΌâÎœe appearance searches, which are sensitive to more than one active-sterile mixing angle. We find that the cosmological data fully exclude the allowed regions published by the LSND, MiniBooNE and Neutrino-4 collaborations, and those from the gallium and rector anomalies, at the 95% Cl. Compared to the exclusion region from the Daya Bay Îœe-disappearance search, the Planck data are more strongly excluding above |Îm412|â0.1eV2 and meffsterileâ0.2eV, with the Daya Bay exclusion being stronger below these values. Compared to the combined Daya Bay/Bugey/MINOS exclusion region on ΜΌâÎœe appearance, the Planck data is more strongly excluding above Îm412â5Ă10-2eV2, with the exclusion strengths of the Planck data and the Daya Bay/Bugey/MINOS combination becoming comparable below this value
Search for heavy neutral leptons decaying into muon-pion pairs in the MicroBooNE detector
We present upper limits on the production of heavy neutral leptons (HNLs) decaying to mu p pairs using data collected with the MicroBooNE liquid-argon time projection chamber (TPC) operating at Fermilab. This search is the first of its kind performed in a liquid-argon TPC. We use data collected in 2017 and 2018 corresponding to an exposure of 2.0 x 10(20) protons on target from the Fermilab Booster Neutrino Beam, which produces mainly muon neutrinos with an average energy of approximate to 800 MeV. HNLs with higher mass are expected to have a longer time of flight to the liquid-argon TPC than Standard Model neutrinos. The data are therefore recorded with a dedicated trigger configured to detect HNL decays that occur after the neutrino spill reaches the detector. We set upper limits at the 90% confidence level on the element vertical bar U-mu 4 vertical bar(2) of the extended PMNS mixing matrix in the range vertical bar U-mu 4 vertical bar(2) <(6.6-0.9) x 10(-7) for Dirac HNLs and vertical bar U-mu 4 vertical bar(2) <(4.7-0.7) x 10(-7) for Majorana HNLs, assuming HNL masses between 260 and 385 MeV and vertical bar U-e4 vertical bar(2) = vertical bar U-tau 4 vertical bar(2) = 0
Strong Coupling Constant from the Photon Structure Function
We extract the value of the strong coupling constant alpha_s from a
single-parameter pointlike fit to the photon structure function F_2^gamma at
large x and Q^2 and from a first five-parameter full (pointlike and hadronic)
fit to the complete F_2^gamma data set taken at PETRA, TRISTAN, and LEP. In
next-to-leading order and the MSbar renormalization and factorization schemes,
we obtain alpha_s(m_Z)=0.1183 +/- 0.0050(exp.)^+0.0029_-0.0028(theor.)
[pointlike] and alpha_s(m_Z)=0.1198 +/- 0.0028(exp.)^+0.0034_-0.0046(theor.)
[pointlike and hadronic]. We demonstrate that the data taken at LEP have
reduced the experimental error by about a factor of two, so that a competitive
determination of alpha_s from F_2^gamma is now possible.Comment: 11 pages, 2 tables, 2 figures. Version accepted for publication by
Phys. Rev. Let
A Proposal for a Three Detector Short-Baseline Neutrino Oscillation Program in the Fermilab Booster Neutrino Beam
A Short-Baseline Neutrino (SBN) physics program of three LAr-TPC detectors
located along the Booster Neutrino Beam (BNB) at Fermilab is presented. This
new SBN Program will deliver a rich and compelling physics opportunity,
including the ability to resolve a class of experimental anomalies in neutrino
physics and to perform the most sensitive search to date for sterile neutrinos
at the eV mass-scale through both appearance and disappearance oscillation
channels. Using data sets of 6.6e20 protons on target (P.O.T.) in the LAr1-ND
and ICARUS T600 detectors plus 13.2e20 P.O.T. in the MicroBooNE detector, we
estimate that a search for muon neutrino to electron neutrino appearance can be
performed with ~5 sigma sensitivity for the LSND allowed (99% C.L.) parameter
region. In this proposal for the SBN Program, we describe the physics analysis,
the conceptual design of the LAr1-ND detector, the design and refurbishment of
the T600 detector, the necessary infrastructure required to execute the
program, and a possible reconfiguration of the BNB target and horn system to
improve its performance for oscillation searches.Comment: 209 pages, 129 figure
The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe
The preponderance of matter over antimatter in the early Universe, the
dynamics of the supernova bursts that produced the heavy elements necessary for
life and whether protons eventually decay --- these mysteries at the forefront
of particle physics and astrophysics are key to understanding the early
evolution of our Universe, its current state and its eventual fate. The
Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed
plan for a world-class experiment dedicated to addressing these questions. LBNE
is conceived around three central components: (1) a new, high-intensity
neutrino source generated from a megawatt-class proton accelerator at Fermi
National Accelerator Laboratory, (2) a near neutrino detector just downstream
of the source, and (3) a massive liquid argon time-projection chamber deployed
as a far detector deep underground at the Sanford Underground Research
Facility. This facility, located at the site of the former Homestake Mine in
Lead, South Dakota, is approximately 1,300 km from the neutrino source at
Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino
charge-parity symmetry violation and mass ordering effects. This ambitious yet
cost-effective design incorporates scalability and flexibility and can
accommodate a variety of upgrades and contributions. With its exceptional
combination of experimental configuration, technical capabilities, and
potential for transformative discoveries, LBNE promises to be a vital facility
for the field of particle physics worldwide, providing physicists from around
the globe with opportunities to collaborate in a twenty to thirty year program
of exciting science. In this document we provide a comprehensive overview of
LBNE's scientific objectives, its place in the landscape of neutrino physics
worldwide, the technologies it will incorporate and the capabilities it will
possess.Comment: Major update of previous version. This is the reference document for
LBNE science program and current status. Chapters 1, 3, and 9 provide a
comprehensive overview of LBNE's scientific objectives, its place in the
landscape of neutrino physics worldwide, the technologies it will incorporate
and the capabilities it will possess. 288 pages, 116 figure
Long-Baseline Neutrino Facility (LBNF) and Deep Underground Neutrino Experiment (DUNE) Conceptual Design Report Volume 2: The Physics Program for DUNE at LBNF
The Physics Program for the Deep Underground Neutrino Experiment (DUNE) at
the Fermilab Long-Baseline Neutrino Facility (LBNF) is described
- âŠ