1,385 research outputs found
Electromagnetic Decays of Heavy Baryons
The electromagnetic decays of the ground state baryon multiplets with one
heavy quark are calculated using Heavy Hadron Chiral Perturbation Theory. The
M1 and E2 amplitudes for S^{*}--> S gamma, S^{*} --> T gamma and S --> T gamma
are separately computed. All M1 transitions are calculated up to
O(1/Lambda_chi^2). The E2 amplitudes contribute at the same order for S^{*}-->
S gamma, while for S^{*} --> T gamma they first appear at O(1/(m_Q
\Lambda_\chi^2)) and for S --> T gamma are completely negligible. The
renormalization of the chiral loops is discussed and relations among different
decay amplitudes are derived. We find that chiral loops involving
electromagnetic interactions of the light pseudoscalar mesons provide a sizable
enhancement of these decay widths. Furthermore, we obtain an absolute
prediction for the widths of Xi^{0'(*)}_c--> Xi^{0}_c gamma and Xi^{-'(*)}_b-->
Xi^{-}_b gamma. Our results are compared to other estimates existing in the
literature.Comment: 17 pages, 3 figures, submitted to Phys. Rev.
Scintillator counters with WLS fiber/MPPC readout for the side muon range detector (SMRD)of the T2K experiment
The T2K neutrino experiment at J-PARC uses a set of near detectors to measure
the properties of an unoscillated neutrino beam and neutrino interaction
cross-sections. One of the sub-detectors of the near-detector complex, the side
muon range detector (SMRD), is described in the paper. The detector is designed
to help measure the neutrino energy spectrum, to identify background and to
calibrate the other detectors. The active elements of the SMRD consist of 0.7
cm thick extruded scintillator slabs inserted into air gaps of the UA1 magnet
yokes. The readout of each scintillator slab is provided through a single WLS
fiber embedded into a serpentine shaped groove. Two Hamamatsu multi-pixel
avalanche photodiodes (MPPC's) are coupled to both ends of the WLS fiber. This
design allows us to achieve a high MIP detection efficiency of greater than
99%. A light yield of 25-50 p.e./MIP, a time resolution of about 1 ns and a
spatial resolution along the slab better than 10 cm were obtained for the SMRD
counters.Comment: 7 pages, 4 figures; talk at TIPP09, March 12-17, Tsukuba, Japan; to
be published in the conference proceeding
Precise 3D track reconstruction algorithm for the ICARUS T600 liquid argon time projection chamber detector
Liquid Argon Time Projection Chamber (LAr TPC) detectors offer charged
particle imaging capability with remarkable spatial resolution. Precise event
reconstruction procedures are critical in order to fully exploit the potential
of this technology. In this paper we present a new, general approach of
three-dimensional reconstruction for the LAr TPC with a practical application
to track reconstruction. The efficiency of the method is evaluated on a sample
of simulated tracks. We present also the application of the method to the
analysis of real data tracks collected during the ICARUS T600 detector
operation with the CNGS neutrino beam.Comment: Submitted to Advances in High Energy Physic
Search for anomalies in the {\nu}e appearance from a {\nu}{\mu} beam
We report an updated result from the ICARUS experiment on the search for
{\nu}{\mu} ->{\nu}e anomalies with the CNGS beam, produced at CERN with an
average energy of 20 GeV and travelling 730 km to the Gran Sasso Laboratory.
The present analysis is based on a total sample of 1995 events of CNGS neutrino
interactions, which corresponds to an almost doubled sample with respect to the
previously published result. Four clear {\nu}e events have been visually
identified over the full sample, compared with an expectation of 6.4 +- 0.9
events from conventional sources. The result is compatible with the absence of
additional anomalous contributions. At 90% and 99% confidence levels the limits
to possible oscillated events are 3.7 and 8.3 respectively. The corresponding
limit to oscillation probability becomes consequently 3.4 x 10-3 and 7.6 x 10-3
respectively. The present result confirms, with an improved sensitivity, the
early result already published by the ICARUS collaboration
Performance Of A Liquid Argon Time Projection Chamber Exposed To The WANF Neutrino Beam
We present the results of the first exposure of a Liquid Argon TPC to a
multi-GeV neutrino beam. The data have been collected with a 50 liters
ICARUS-like chamber located between the CHORUS and NOMAD experiments at the
CERN West Area Neutrino Facility (WANF). We discuss both the instrumental
performance of the detector and its capability to identify and reconstruct low
multiplicity neutrino interactions.Comment: 14 pages, 12 figures. Submitted for publication to Physical Review
A search for the analogue to Cherenkov radiation by high energy neutrinos at superluminal speeds in ICARUS
The OPERA collaboration has claimed evidence of superluminal {\nu}{_\mu}
propagation between CERN and the LNGS. Cohen and Glashow argued that such
neutrinos should lose energy by producing photons and e+e- pairs, through Z0
mediated processes analogous to Cherenkov radiation. In terms of the parameter
delta=(v^2_nu-v^2_c)/v^2_c, the OPERA result implies delta = 5 x 10^-5. For
this value of \delta a very significant deformation of the neutrino energy
spectrum and an abundant production of photons and e+e- pairs should be
observed at LNGS. We present an analysis based on the 2010 and part of the 2011
data sets from the ICARUS experiment, located at Gran Sasso National Laboratory
and using the same neutrino beam from CERN. We find that the rates and
deposited energy distributions of neutrino events in ICARUS agree with the
expectations for an unperturbed spectrum of the CERN neutrino beam. Our results
therefore refute a superluminal interpretation of the OPERA result according to
the Cohen and Glashow prediction for a weak current analog to Cherenkov
radiation. In particular no superluminal Cherenkov like e+e- pair or gamma
emission event has been directly observed inside the fiducial volume of the
"bubble chamber like" ICARUS TPC-LAr detector, setting the much stricter limit
of delta < 2.5 10^-8 at the 90% confidence level, comparable with the one due
to the observations from the SN1987A.Comment: 17 pages, 6 figure
SVZ sum rules : 30 + 1 years later
For this exceptional 25th anniversary of the QCD-Montpellier series of
conferences initiated in 85 with the name "Non-perturbative methods", we take
the opportunuity to celebrate the 30 + 1 years of the discovery of the SVZ
(also called ITEP, QCD or QCD spectral) sum rules by M.A. Shifman, A.I.
Vainshtein and V.I. Zakahrov in 79 [1]. In this talk, I have the duty to
present the status of the method. I shall (can) not enumerate the vast area of
successful applications of sum rules in hadron physics but I shall focus on the
historical evolution of field and its new developments. More detailed related
discussions and more complete references can be found in the textbooks [2,3].Comment: 8 pages, 1 figure, 4 tables, talk given at QCD 10 (15th international
QCD-Montpellier conference) for the celebration of the 25th anniversary of
the QCD series of Montpellier conference and of the 30+1 years discovery of
the SVZ sum rule
The T2K Side Muon Range Detector
The T2K experiment is a long baseline neutrino oscillation experiment aiming
to observe the appearance of {\nu} e in a {\nu}{\mu} beam. The {\nu}{\mu} beam
is produced at the Japan Proton Accelerator Research Complex (J-PARC), observed
with the 295 km distant Super- Kamiokande Detector and monitored by a suite of
near detectors at 280m from the proton target. The near detectors include a
magnetized off-axis detector (ND280) which measures the un-oscillated neutrino
flux and neutrino cross sections. The present paper describes the outermost
component of ND280 which is a side muon range detector (SMRD) composed of
scintillation counters with embedded wavelength shifting fibers and Multi-Pixel
Photon Counter read-out. The components, performance and response of the SMRD
are presented.Comment: 13 pages, 19 figures v2: fixed several typos; fixed reference
The LAGUNA design study- towards giant liquid based underground detectors for neutrino physics and astrophysics and proton decay searches
The feasibility of a next generation neutrino observatory in Europe is being
considered within the LAGUNA design study. To accommodate giant neutrino
detectors and shield them from cosmic rays, a new very large underground
infrastructure is required. Seven potential candidate sites in different parts
of Europe and at several distances from CERN are being studied: Boulby (UK),
Canfranc (Spain), Fr\'ejus (France/Italy), Pyh\"asalmi (Finland),
Polkowice-Sieroszowice (Poland), Slanic (Romania) and Umbria (Italy). The
design study aims at the comprehensive and coordinated technical assessment of
each site, at a coherent cost estimation, and at a prioritization of the sites
within the summer 2010.Comment: 5 pages, contribution to the Workshop "European Strategy for Future
Neutrino Physics", CERN, Oct. 200
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