5,424 research outputs found
High scale perturbative gauge coupling in R-parity conserving SUSY SO(10) with longer proton lifetime
It is well known that in single step breaking of R-parity conserving SUSY
SO(10) that needs the Higgs representations the GUT-gauge
coupling violates the perturbative constraint at mass scales few times larger
than the GUT scale. Therefore, if the SO(10) gauge coupling is to remain
perturbative up the Planck scale(=2x10^{18} GeV), the scale of GUT
symmetry breaking is to be bounded from below. The bound depends upon specific
Higgs representations used for SO(10) symmetry breaking but, as we find, can
not be lower than GeV. In order to obtain such high unification
scale we propose a two-step SO(10) breaking through
intermediate gauge
symmetry. We estimate potential threshold and gravitational corrections to the
running of gauge couplings and show that they can make the picture of
perturbative GUT- gauge coupling running consistent at least up to the Planck
scale. We also show that when by ,
gravitational corrections alone with negligible threshold effects may guarantee
such perturbative gauge coupling. The lifetime of the proton is found to
increase by nearly 6 orders over the current experimental limit for . For the proton decay mediated by dim.5 operator a wide range of
lifetimes is possible extending from the current experimental limit up to
values 2-3 orders longer.Comment: 11 pages epjc LaTex as per specifications of European Physical
Journal
Vanishing corrections on the intermediate scale and implications for unification of forces
In two-step breaking of a class of grand unified theories including SO(10),we
prove a theorem showing that the scale where the Pati-Salam gauge
symmetry with parity breaks down to the standard gauge group,has vanishing
corrections due to all sources emerging from higher scales such as
the one-loop and all higher loop effects,the GUT-threshold,gravitational
smearing,and string threshold effects. Implications of such a scale for the
unification of gauge couplings with small Majorana neutrino masses are
discussed.In string inspired SO(10) we show that ,needed for neutrino masses,with the GUT scale can
be realized provided certain particle states in the predicted spectum are
light.Comment: 21 pages, Late
Precision and uncertainties in mass scale predictions in SUSY SO(10) with SU(2)_L x SU(2)_R x U(1)_{B-L} x SU(3)_C intermediate breaking
In a class of SUSY SO(10) with
intermediate gauge symmetry, we observe that the
prediction on the unification mass is unaffected by
Planck-scale-induced gravitational and intermediate-scale-threshold effects,
although the intermediate scale itself is subject to such corrections.
In particular, without invoking the presence of additional lighter scalar
degrees of freedom but including plausible and reasonable threshold effects, we
find that interesting solutions for neutrino physics corresponding to
GeV and GeV are
permitted in the minimal models. Possibilities of low-mass right-handed gauge
bosons corresponding to TeV consistent with the CERN-LEP data
are pointed out in a number of models when threshold effects are included using
effective mass parameters.Comment: 12 pages including 7 tables (Typos corrected as per the published
version
Genetic and antigenic characterisation of serotype A FMD viruses from East Africa to select new vaccine strains
Vaccine strain selection for emerging foot-and-mouth disease virus (FMDV) outbreaks in enzootic countries can be addressed through antigenic and genetic characterisation of recently circulating viruses. A total of 56 serotype A FMDVs isolated between 1998 and 2012, from Central, East and North African countries were characterised antigenically by virus neutralisation test using antisera to three existing and four candidate vaccine strains and, genetically by characterising the full capsid sequence data. A Bayesian analysis of the capsid sequence data revealed the viruses to be of either African or Asian topotypes with subdivision of the African topotype viruses into four genotypes (Genotypes I, II, IV and VII). The existing vaccine strains were found to be least cross-reactive (good matches observed for only 5.4–46.4% of the sampled viruses). Three bovine antisera, raised against A-EA-2007, A-EA-1981 and A-EA-1984 viruses, exhibited broad cross-neutralisation, towards more than 85% of the circulating viruses. Of the three vaccines, A-EA-2007 was the best showing more than 90% in-vitro cross-protection, as well as being the most recent amongst the vaccine strains used in this study. It therefore appears antigenically suitable as a vaccine strain to be used in the region in FMD control programmes
Feasibility of using ultrasonic technique to measure the blast furnace lining thickness
Blast furnace process has been the most effective way to produce iron for over 200 years.Throughout the years, large efforts have been put on finding ways to increase the productivity and extend the campaign length. The condition of the refractory lining of a blast furnace plays a very important role to determine its campaign length. Many methods have been employed to measure blast furnace lining thickness including radioisotopes, thermal measurement and core-drilling. Temperature measurement is among the most widely used method for on-line monitoring the profile of the blast furnace inner surface, which is based on
numerically solving inverse problem using heat transfer models and readings from thermocouple. Optimization methods are applied to obtain the boundary of the domain iteratively, and hence the computation is very expensive and calculation cannot be very accurate. This paper presents the feasibility of using non-invasive ultrasonic technique in bistatic mode to measure the profile of the refractory liner of the hearth region of blast furnace
Non-linear ultrasonic technique to assess fatigue damage in structural steel
A non-linear ultrasonic technique has been used to assess the fatigue damage in low carbon structural steel. The percentage of total harmonic distortion, which is the ratio of the amplitude of 2nd harmonic and the fundamental, has been introduced as the measurement parameter in this paper. It has also been observed that before crack initiation the 2nd harmonic amplitude is comparable to the fundamental. The results have been analysed in light of the dislocation theory for harmonic generation during material degradation
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