321 research outputs found
Classical running of neutrino masses from six dimensions
We discuss a six dimensional mass generation for the neutrinos. Active
neutrinos live on a three-brane and interact via a brane localized mass term
with a bulk six-dimensional standard model singlet (sterile) Weyl fermion, the
two dimensions being transverse to the three-brane.
We derive the physical neutrino mass spectrum and show that the active
neutrino mass and Kaluza-Klein masses have a logarithmic cutoff divergence
related to the zero-size limit of the three-brane in the transverse space. This
translates into a renormalisation group running of the neutrino masses above
the Kaluza-Klein compactification scale coming from classical effects, without
any new non-singlet particles in the spectrum. For compact radii in the eV--MeV
range, relevant for neutrino physics, this scenario predicts running neutrino
masses which could affect, in particular, neutrinoless double beta decay
experiments.Comment: 23 pages, 2 figure
Running Neutrino Mass from Six Dimensions
In the present talk, we will discuss a six dimensional mass generation for the neutrinos. The SM neutrinos live on a 3-brane and interact via a brane localised mass term with a Weyl singlet neutrino residing in all the six dimensions. We present the physical neutrino mass spectrum and show that the active neutrino mass and the KK masses have a logarithmic cut-off dependence at the tree level. This translates in to a renormalisation group running of n -masses above the KK compactification scale coming from classical effects without any SM particles in the spectrum.This could have effects in neutrinoless double beta decay experiments
Neutrino Mass Constraints on R violation and HERA anomaly
R parity violating trilinear couplings of the minimal
supersymmetric standard model (MSSM) are constrained from the limit on the
electron neutrino mass. Strong limits on these couplings follow from the
earlier neglected contribution due to sneutrino vacuum expectation values. The
limits on most of the couplings derived here are stronger than
the existing ones for a wide range in parameters of MSSM. These limits strongly
constrain the interpretation of recent HERA results in scattering in
terms of production of squarks through violating couplings. In particular,
the interpretation in terms of production off strange quark as
suggested recently is not viable for wide ranges in MSSM parameters.Comment: 15 pages with 5 figures, minor typos corrected and a new reference
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Lepton Flavor Violation, Neutralino Dark Matter and the Reach of the LHC
We revisit the phenomenology of the Constrained MSSM with right-handed
neutrinos (CMSSMRN). A supersymmetric seesaw mechanism, generating neutrino
masses and sizable lepton flavour violating (LFV) entries is assumed to be
operative. In this scheme, we study the complementarity between the `observable
ranges' of various paths leading to the possible discovery of low energy SUSY:
the reach of the Cern Large Hadron Collider (LHC), the quest for neutralino
dark matter signals and indirect searches through LFV processes. Within the
regions of the CMSSMRN parameter space compatible with all
cosmo-phenomenological requirements, those which are expected to be probed at
the LHC will be typically also accessible to upcoming LFV experiments.
Moreover, parameter space portions featuring a heavy SUSY particle spectrum
could be well beyond LHC reach while leaving LFV searches as the only key to
get a glimpse on SUSY.Comment: 31 pages, 12 figures, LateX; v2: one reference and one comment added;
matches with published versio
Type I seesaw mechanism for quasi degenerate neutrinos
We discuss symmetries and scenarios leading to quasi-degenerate neutrinos in
type-I seesaw models. The existence of degeneracy in the present approach is
not linked to any specific structure for the Dirac neutrino Yukawa coupling
matrix and holds in general. Basic input is the application of the
minimal flavour violation principle to the leptonic sector. Generalizing this
principle, we assume that the structure of the right handed neutrino mass
matrix is determined by and the charged lepton Yukawa coupling matrix
in an effective theory invariant under specific groups
contained in the full symmetry group of the kinetic energy terms.
invariance also leads to specific structure for the departure from degeneracy.
The neutrino mass matrix (with degenerate mass ) resulting after seesaw
mechanism has a simple form in one
particular scenario based on supersymmetry. This form is shown to lead to
correct description of neutrino masses and mixing angles. The thermal
leptogenesis after inclusion of flavour effects can account for the observed
baryon asymmetry of the universe within the present scenario. Rates for lepton
flavour violating processes can occur at observable levels in the
supersymmetric version of the scenario.Comment: 14 pages; two figure
Fluorescence from graphene oxide and the influence of ionic, π π interactions and heterointerfaces: electron or energy transfer dynamics
Cataloged from PDF version of article.2D crystals such as graphene and its oxide counterpart have sought good research attention for their application as well as fundamental interest. Especially graphene oxide (GO) is quite interesting because of its versatility and diverse application potential. However the mechanism of fluorescence from GO is under severe discussion. To explain the emission in general two interpretations were suggested, viz localization of sp2 clusters and involvement of oxygeneous functional groups. Despite this disagreement, it should be acknowledged that the heterogeneous atomic structure, synthesis dependent and uncontrollable implantation of oxygen functional groups on the basal plane make such explanations more difficult. Nevertheless, a suitable explanation enhances the applicability of the material which also enables the design of novel materials. At this juncture we believe that given the complexity in understanding the emission mechanism it would be very useful to review the literature. In this perspective we juxtapose various results related to fluorescence and influencing factors so that a conclusive interpretation may be unveiled. Apparently, the existing interpretations have largely ignored the factors such as self-rolling, byproduct formation etc. Vis-a-vis previous reviews did not discuss the interfacial charge transfer across heterostructures and the implication on the optical properties of GO or reduced graphene oxide (rGO). Such analysis would be very insightful to determine the energetic location of sub band gap states. Moreover, ionic and π-π type interactions are also considered for their influence on emission properties. Apart from these, quantum dots, covalent modifications and nonlinear optical properties of GO and rGO were discussed for completeness. Finally we made concluding remarks with outlook. © the Partner Organisations 2014
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