484 research outputs found
Decay and Decoupling of heavy Right-handed Majorana Neutrinos in the L-R model
Heavy right-handed neutrinos are of current interest. The interactions and
decay of such neutrinos determine their decoupling epoch during the evolution
of the universe. This in turn affects various observable features like the
energy density, nucleosynthesis, CMBR spectrum, galaxy formation, and
baryogenesis. Here, we consider reduction of right-handed electron-type
Majorana neutrinos, in the left-right symmetric model, by the WR+ - WR- channel
and the channel originating from an anomaly, involving the SU(2)R gauge group,
as well as decay of such neutrinos. We study the reduction of these neutrinos
for different ranges of left-right model parameters, and find that, if the
neutrino mass exceeds the right-handed gauge boson mass, then the neutrinos
never decouple for realistic values of the parameters, but, rather, decay in
equilibrium. Because there is no out-of-equilibrium decay, no mass bounds can
be set for the neutrinos.Comment: Latex, 16 pages, No figures. Some additions in the text and
references. Conclusions unaffected. To appear in Eur. Phys. J.
Current sheet formation and nonideal behavior at three-dimensional magnetic null points
The nature of the evolution of the magnetic field, and of current sheet
formation, at three-dimensional (3D) magnetic null points is investigated. A
kinematic example is presented which demonstrates that for certain evolutions
of a 3D null (specifically those for which the ratios of the null point
eigenvalues are time-dependent) there is no possible choice of boundary
conditions which renders the evolution of the field at the null ideal.
Resistive MHD simulations are described which demonstrate that such evolutions
are generic. A 3D null is subjected to boundary driving by shearing motions,
and it is shown that a current sheet localised at the null is formed. The
qualitative and quantitative properties of the current sheet are discussed.
Accompanying the sheet development is the growth of a localised parallel
electric field, one of the signatures of magnetic reconnection. Finally, the
relevance of the results to a recent theory of turbulent reconnection is
discussed.Comment: to appear in Phys. Plasmas. A version with higher quality figures can
be found at http://www.maths.dundee.ac.uk/~dpontin/ In this replacement
version, typos have been corrected, and in addition references and some
further discussion adde
Effects of SO(10) D-Terms on SUSY Signals at the Tevatron
We study signals for the production of superparticles at the Tevatron in
supergravity scenarios based on the Grand Unified group SO(10). The breaking of
this group introduces extra contributions to the masses of all scalars,
described by a single new parameter. We find that varying this parameter can
considerably change the size of various expected signals studied in the
literature, with different numbers of jets and/or charged leptons in the final
state. The ratios of these signal can thus serve as a diagnostic to detect or
constrain deviations from the much--studied scenario where all scalar masses
are universal at the GUT scale. Moreover, under favorable circumstances some of
these signals, and/or new signals involving hard jets, should be observable
at the next run of the Tevatron collider even if the average scalar mass lies
well above the gluino mass.Comment: 17 pages, LaTeX including 3 postscript figures, uses equation.st
LHC Signature of the Minimal SUGRA Model with a Large Soft Scalar Mass
Thanks to the focus point phenomenon, it is quite {\it natural} for the
minimal SUGRA model to have a large soft scalar mass m_0 > 1 TeV. A distinctive
feature of this model is an inverted hierarchy, where the lighter stop has a
significantly smaller mass than the other squarks and sleptons. Consequently,
the gluino is predicted to decay dominantly via stop exchange into a channel
containing 2b and 2W along with the LSP. We exploit this feature to construct a
robust signature for this model at the LHC in leptonic channels with 3-4 b-tags
and a large missing-E_T.Comment: Small clarifications added. Final version to appear in Phys. Lett.
Intervalence charge transfer transition in mixed valence complexes synthesised from Ru<SUP>III</SUP>(edta)- and Fe<SUP>II</SUP>(CN)<SUB>5</SUB>-cores
Intervalence charge transfer properties were studied for a set of mixed valence complexes incorporating Ru(III) and Fe(II)-centres linked by various saturated and unsaturated bridging ligands (BL). Studies reveal that degree of ground state electronic interaction and coupling between Ru(III) and Fe(II)-centres can be attenuated by changing the nature of the bridging ligand. Further, inclusion of the bridging ligand with interrupted π-electron system in a β-CD cavity initiate an optical electron transfer from Fe(II) to Ru(III) which is otherwise not observed
N-Butyl acrylate polymer composition for solar cell encapsulation and method
A polymer syrup for encapsulating solar cell assemblies. The syrup includes uncrosslinked poly(n-butyl)acrylate dissolved in n-butyl acrylate monomer. Preparation of the poly(n-butyl)acrylate and preparation of the polymer syrup is disclosed. Methods for applying the polymer syrup to solar cell assemblies as an encapsulating pottant are described. Also included is a method for solar cell construction utilizing the polymer syrup as a dual purpose adhesive and encapsulating material
A GEANT-based study of atmospheric neutrino oscillation parameters at INO
We have studied the dependence of the allowed space of the atmospheric
neutrino oscillation parameters on the time of exposure for a magnetized Iron
CALorimeter (ICAL) detector at the India-based Neutrino Observatory (INO). We
have performed a Monte Carlo simulation for a 50 kTon ICAL detector generating
events by the neutrino generator NUANCE and simulating the detector response by
GEANT. A chi-square analysis for the ratio of the up-going and down-going
neutrinos as a function of is performed and the allowed regions at 90%
and 99% CL are displayed. These results are found to be better than the current
experimental results of MINOS and Super-K. The possibilities of further
improvement have also been discussed.Comment: 8 pages, 13 figures, a new figure added, version accepted in IJMP
C5′- and C3′-sugar radicals produced via photo-excitation of one-electron oxidized adenine in 2′-deoxyadenosine and its derivatives
We report that photo-excitation of one-electron-oxidized adenine [A(-H)•] in dAdo and its 2′-deoxyribonucleotides leads to formation of deoxyribose sugar radicals in remarkably high yields. Illumination of A(-H)• in dAdo, 3′-dAMP and 5′-dAMP in aqueous glasses at 143 K leads to 80-100% conversion to sugar radicals at C5′ and C3′. The position of the phosphate in 5′- and 3′-dAMP is observed to deactivate radical formation at the site of substitution. In addition, the pH has a crucial influence on the site of sugar radical formation; e.g. at pH ∼5, photo-excitation of A(-H)• in dAdo at 143 K produces mainly C5′• whereas only C3′• is observed at high pH ∼12. (13)C substitution at C5′ in dAdo yields (13)C anisotropic couplings of (28, 28, 84) G whose isotropic component 46.7 G identifies formation of the near planar C5′•. A β-(13)C 16 G isotropic coupling from C3′• is also found. These results are found to be in accord with theoretically calculated (13)C couplings at C5′ [DFT, B3LYP, 6-31(G) level] for C5′• and C3′•. Calculations using time-dependent density functional theory [TD-DFT B3LYP, 6-31G(d)] confirm that transitions in the near UV and visible induce hole transfer from the base radical to the sugar group leading to sugar radical formation
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