730 research outputs found
Signatures of black holes at the LHC
Signatures of black hole events at CERN's Large Hadron Collider are
discussed. Event simulations are carried out with the Fortran Monte Carlo
generator CATFISH. Inelasticity effects, exact field emissivities, color and
charge conservation, corrections to semiclassical black hole evaporation,
gravitational energy loss at formation and possibility of a black hole remnant
are included in the analysis.Comment: 13 pages, 7 figure
Thermal Unparticles: A New Form of Energy Density in the Universe
Unparticle \U with scaling dimension d_\U has peculiar thermal properties
due to its unique phase space structure. We find that the equation of state
parameter \omega_\U, the ratio of pressure to energy density, is given by
1/(2d_\U +1) providing a new form of energy in our universe. In an expanding
universe, the unparticle energy density \rho_\U(T) evolves dramatically
differently from that for photons. For d_\U >1, even if \rho_\U(T_D) at a
high decoupling temperature is very small, it is possible to have a large
relic density \rho_\U(T^0_\gamma) at present photon temperature ,
large enough to play the role of dark matter. We calculate and
\rho_\U(T^0_\gamma) using photon-unparticle interactions for illustration.Comment: 5 pages; v3, journal version
Generating a checking sequence with a minimum number of reset transitions
Given a finite state machine M, a checking sequence is an input sequence that is guaranteed to lead to a failure if the implementation under test is faulty and has no more states than M. There has been much interest in the automated generation of a short checking sequence from a finite state machine. However, such sequences can contain reset transitions whose use can adversely affect both the cost of applying the checking sequence and the effectiveness of the checking sequence. Thus, we sometimes want a checking sequence with a minimum number of reset transitions rather than a shortest checking sequence. This paper describes a new algorithm for generating a checking sequence, based on a distinguishing sequence, that minimises the number of reset transitions used.This work was supported in part by Leverhulme Trust grant number F/00275/D, Testing State Based Systems, Natural Sciences and Engineering Research Council (NSERC) of Canada grant number RGPIN 976, and Engineering and Physical Sciences Research Council grant number GR/R43150, Formal Methods and Testing (FORTEST)
Nab: Measurement Principles, Apparatus and Uncertainties
The Nab collaboration will perform a precise measurement of 'a', the
electron-neutrino correlation parameter, and 'b', the Fierz interference term
in neutron beta decay, in the Fundamental Neutron Physics Beamline at the SNS,
using a novel electric/magnetic field spectrometer and detector design. The
experiment is aiming at the 10^{-3} accuracy level in (Delta a)/a, and will
provide an independent measurement of lambda = G_A/G_V, the ratio of
axial-vector to vector coupling constants of the nucleon. Nab also plans to
perform the first ever measurement of 'b' in neutron decay, which will provide
an independent limit on the tensor weak coupling.Comment: 12 pages, 6 figures, 1 table, talk presented at the International
Workshop on Particle Physics with Slow Neutrons, Grenoble, 29-31 May 2008; to
appear in Nucl. Instrum. Meth. in Physics Research
Sparticle Spectra and LHC Signatures for Large Volume String Compactifications
We study the supersymmetric particle spectra and LHC collider observables for
the large-volume string models with a fundamental scale of 10^{11} GeV that
arise in moduli-fixed string compactifications with branes and fluxes. The
presence of magnetic fluxes on the brane world volume, required for chirality,
perturb the soft terms away from those previously computed in the dilute-flux
limit. We use the difference in high-scale gauge couplings to estimate the
magnitude of this perturbation and study the potential effects of the magnetic
fluxes by generating many random spectra with the soft terms perturbed around
the dilute flux limit. Even with a 40% variation in the high-scale soft terms
the low-energy spectra take a clear and predictive form. The resulting spectra
are broadly similar to those arising on the SPS1a slope, but more degenerate.
In their minimal version the models predict the ratios of gaugino masses to be
M_1 : M_2 : M_3=(1.5 - 2) : 2 : 6, different to both mSUGRA and mirage
mediation. Among the scalars, the squarks tend to be lighter and the sleptons
heavier than for comparable mSUGRA models. We generate 10 fb^{-1} of sample LHC
data for the random spectra in order to study the range of collider
phenomenology that can occur. We perform a detailed mass reconstruction on one
example large-volume string model spectrum. 100 fb^{-1} of integrated
luminosity is sufficient to discriminate the model from mSUGRA and aspects of
the sparticle spectrum can be accurately reconstructed.Comment: 42 pages, 21 figures. Added references and discussion for section 3.
Slight changes in the tex
A renormalizable SO(10) GUT scenario with spontaneous CP violation
We consider fermion masses and mixings in a renormalizable SUSY SO(10) GUT
with Yukawa couplings of scalar fields in the representation 10 + 120 + 126
bar. We investigate a scenario defined by the following assumptions: i) A
single large scale in the theory, the GUT scale. ii) Small neutrino masses
generated by the type I seesaw mechanism with negligible type II contributions.
iii) A suitable form of spontaneous CP breaking which induces hermitian mass
matrices for all fermion mass terms of the Dirac type. Our assumptions define
an 18-parameter scenario for the fermion mass matrices for 18 experimentally
known observables. Performing a numerical analysis, we find excellent fits to
all observables in the case of both the normal and inverted neutrino mass
spectrum.Comment: 16 pages, two eps figure
Neutral Higgs bosons in the MNMSSM with explicit CP violation
Within the framework of the minimal non-minimal supersymmetric standard model
(MNMSSM) with tadpole terms, CP violation effects in the Higgs sector are
investigated at the one-loop level, where the radiative corrections from the
loops of the quark and squarks of the third generation are taken into account.
Assuming that the squark masses are not degenerate, the radiative corrections
due to the stop and sbottom quarks give rise to CP phases, which trigger the CP
violation explicitly in the Higgs sector of the MNMSSM. The masses, the
branching ratios for dominant decay channels, and the total decay widths of the
five neutral Higgs bosons in the MNMSSM are calculated in the presence of the
explicit CP violation. The dependence of these quantities on the CP phases is
quite recognizable, for given parameter values.Comment: 25 pages, 8 figure
Partial wave analysis of J/\psi \to \gamma \phi \phi
Using events collected in the BESII detector, the
radiative decay is
studied. The invariant mass distribution exhibits a near-threshold
enhancement that peaks around 2.24 GeV/.
A partial wave analysis shows that the structure is dominated by a
state () with a mass of
GeV/ and a width of GeV/. The
product branching fraction is: .Comment: 11 pages, 4 figures. corrected proof for journa
Direct Measurements of Absolute Branching Fractions for D0 and D+ Inclusive Semimuonic Decays
By analyzing about 33 data sample collected at and around 3.773
GeV with the BES-II detector at the BEPC collider, we directly measure the
branching fractions for the neutral and charged inclusive semimuonic decays
to be and , and determine the ratio of the two branching
fractions to be
Measurements of the observed cross sections for exclusive light hadron production in e^+e^- annihilation at \sqrt{s}= 3.773 and 3.650 GeV
By analyzing the data sets of 17.3 pb taken at GeV
and 6.5 pb taken at GeV with the BESII detector at the
BEPC collider, we have measured the observed cross sections for 12 exclusive
light hadron final states produced in annihilation at the two energy
points. We have also set the upper limits on the observed cross sections and
the branching fractions for decay to these final states at 90%
C.L.Comment: 8 pages, 5 figur
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