2,734 research outputs found
Consistent two--dimensional chiral gravity
We study chiral induced gravity in the light-cone gauge and show that the
theory is consistent for a particular choice of chiralities. The corresponding
Kac--Moody central charge has no forbidden region of complex values.
Generalized analysis of the critical exponents is given and their relation to
the vacuum states is elucidated. All the parameters containing
information about the theory can be traced back to the characteristics of the
group of residual symmetry in the light--cone gauge.Comment: 38 pages, LateX, to appear in Int.J.Mod.Phys.
A Multivariate Training Technique with Event Reweighting
An event reweighting technique incorporated in multivariate training
algorithm has been developed and tested using the Artificial Neural Networks
(ANN) and Boosted Decision Trees (BDT). The event reweighting training are
compared to that of the conventional equal event weighting based on the ANN and
the BDT performance. The comparison is performed in the context of the physics
analysis of the ATLAS experiment at the Large Hadron Collider (LHC), which will
explore the fundamental nature of matter and the basic forces that shape our
universe. We demonstrate that the event reweighting technique provides an
unbiased method of multivariate training for event pattern recognition.Comment: 20 pages, 8 figure
Symmetric Textures in SO(10) and LMA Solution for Solar Neutrinos
We analyze a model based on SUSY SO(10) combined with SU(2) family symmetry
and symmetric mass matrices constructed by the authors recently. Previously,
only the parameter space for the LOW and vacuum oscillation (VO) solutions was
investigated. We indicate in this note the parameter space which leads to large
mixing angle (LMA) solution to the solar neutrino problem with a slightly
modified effective neutrino mass matrix. The symmetric mass textures arising
from the left-right symmetry breaking and the SU(2) symmetry breaking give rise
to very good predictions for the quark and lepton masses and mixing angles. The
prediction of our model for the |U_{e\nu_{3}}| element in the
Maki-Nakagawa-Sakata (MNS) matrix is close to the sensitivity of current
experiments; thus the validity of our model can be tested in the near future.
We also investigate the correlation between the |U_{e\nu_{3}}| element and
\tan^{2}\theta_{\odot} in a general two-zero neutrino mass texture.Comment: RevTeX4; 9 pages; 1 figur
A Submillimeter HCN Laser in IRC+10216
We report the detection of a strong submillimeter wavelength HCN laser line
at a frequency near 805 GHz toward the carbon star IRC+10216. This line, the
J=9-8 rotational transition within the (04(0)0) vibrationally excited state, is
one of a series of HCN laser lines that were first detected in the laboratory
in the early days of laser spectroscopy. Since its lower energy level is 4200 K
above the ground state, the laser emission must arise from the inner part of
IRC+10216's circumstellar envelope. To better characterize this environment, we
observed other, thermally emitting, vibrationally excited HCN lines and find
that they, like the laser line, arise in a region of temperature approximately
1000 K that is located within the dust formation radius; this conclusion is
supported by the linewidth of the laser. The (04(0)0), J=9-8 laser might be
chemically pumped and may be the only known laser (or maser) that is excited
both in the laboratory and in space by a similar mechanism.Comment: 11 pages, 3 figure
Clusters, phason elasticity, and entropic stabilisation: a theory perspective
Personal comments are made about the title subjects, including: the relation
of Friedel oscillations to Hume-Rothery stabilisation; how calculations may
resolve the random-tiling versus ideal pictures of quasicrystals; and the role
of entropies apart from tile-configurational.Comment: IOP macros; 8pp, 1 figure. In press, Phil. Mag. A (Proc. Intl. Conf.
on Quasicrystals 9, Ames Iowa, May 2005
Kaon B Parameter in Quenched QCD
I calculate the kaon B-parameter with a lattice simulation in quenched
approximation. The lattice simulation uses an action possessing exact lattice
chiral symmetry, an overlap action. Computations are performed at two lattice
spacings, about 0.13 and 0.09 fm (parameterized by Wilson gauge action
couplings beta=5.9 and 6.1) with nearly the same physical volumes and quark
masses. I describe particular potential difficulties which arise due to the use
of such a lattice action in finite volume. My results are consistent with other
recent lattice determinations using domain-wall fermions.Comment: 23 pages, Revtex, 16 postscript figure
Evidence for the Appearance of Atmospheric Tau Neutrinos in Super-Kamiokande
Super-Kamiokande atmospheric neutrino data were fit with an unbinned maximum
likelihood method to search for the appearance of tau leptons resulting from
the interactions of oscillation-generated tau neutrinos in the detector.
Relative to the expectation of unity, the tau normalization is found to be
1.42 \pm 0.35 \ (stat) {\}^{+0.14}_{-0.12}\ (syst) excluding the
no-tau-appearance hypothesis, for which the normalization would be zero, at the
3.8 level. We estimate that 180.1 \pm 44.3\ (stat)
{\}^{+17.8}_{-15.2}\ (syst) tau leptons were produced in the 22.5 kton
fiducial volume of the detector by tau neutrinos during the 2806 day running
period. In future analyses, this large sample of selected tau events will allow
the study of charged current tau neutrino interaction physics with oscillation
produced tau neutrinos.Comment: 7 pages, 4 figures. This is the version as published in Physical
Review Letters including the supplemental figure. A typographical error in
the description of figure 3 is also correcte
A Quench Detection and Monitoring System for Superconducting Magnets at Fermilab
A quench detection system was developed for protecting and monitoring the
superconducting solenoids for the Muon-to-Electron Conversion Experiment (Mu2e)
at Fermilab. The quench system was designed for a high level of dependability
and long-term continuous operation. It is based on three tiers: Tier-I,
FPGA-based Digital Quench Detection (DQD); Tier-II, Analog Quench Detection
(AQD); and Tier-3, the quench controls and data management system. The Tier-I
and Tier-II are completely independent and fully redundant systems. The Tier-3
system is based on National Instruments (NI) C-RIO and provides the user
interface for quench controls and data management. It is independent from Tiers
I & II. The DQD provides both quench detection and quench characterization
(monitoring) capability. Both DQD and AQD have built-in high voltage isolation
and user programmable gains and attenuations. The DQD and AQD also includes
user configured current dependent thresholding and validation times.
A 1st article of the three-tier system was fully implemented on the new
Fermilab magnet test stand for the HL-LHC Accelerator Up-grade Project (AUP).
It successfully provided quench protection and monitoring (QPM) for a cold
superconducting bus test in November 2020. The Mu2e quench detection design has
since been implemented for production testing of the AUP magnets. A detailed
description of the system along with results from the AUP superconducting bus
test will be presented
Dpes massless QCD have vacuum energy?
It is widely thought that this question has a positive answer, but we argue
that the support for this belief from both experiment and theory is weak or
nonexistent. We then list some of the ramifications of a negative answer.Comment: 8 pages, no figures, version to appear in NJ
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