26,143 research outputs found
The Frobenius group T13 and the canonical see-saw mechanism applied to neutrino mixing
The compatibility of the Frobenius group T13 with the canonical see-saw
mechanism of neutrino mixing is examined. The Standard Model is extended in a
minimalist way, by introducing a family symmetry and three right-handed
neutrinos. To fit experiments and place constraints on the possibilities,
tribimaximal mixing is used as a guideline. The application of both a family
symmetry group and the canonical see-saw mechanism naturally generates small
neutrino masses. The various possibilities from combining these two models are
listed. Enough constraints are produced to narrow down the parameters of the
neutrino mass matrix to two. This is therefore a predictive model where
neutrino mass eigenvalues and allowed regions for neutrinoless double beta
decay are suggested.Comment: Accepted for publication in Physical Review D. 13 page
Quark-lepton symmetry and complementarity
We argue that the difference between the observed approximate quark-lepton
complementarity and the theoretical prediction based on realistic quark-lepton
symmetry within the seesaw mechanism may be adjusted by means of a triplet
contribution in the seesaw formula.Comment: 7 pages, RevTex
Effects of an extra U(1) axial condensate on the strong decays of pseudoscalar mesons
We consider a scenario (supported by some lattice results) in which a
U(1)-breaking condensate survives across the chiral transition in QCD. This
scenario has important consequences for the pseudoscalar-meson sector, which
can be studied using an effective Lagrangian model. In particular, generalizing
the results obtained in two previous papers, where the effects on the radiative
decays eta,eta' --> gamma gamma were studied, in this paper we study the
effects of the U(1) chiral condensate on the strong decays of the "light"
pseudoscalar mesons, i.e., eta,eta' --> 3pi^0; eta,eta' --> pi^+ pi^- pi^0;
eta' --> eta pi^0 pi^0; eta' --> eta pi^+ pi^-; and also on the strong decays
of an exotic ("heavy") SU(3)-singlet pseudoscalar state eta_X, predicted by the
model.Comment: One misprint in Eq. (2.10) has been eliminated; Eqs. (B.8) and (B.9)
in Appendix B have been corrected; 46 pages, 1 tabl
GeV Majorana Neutrinos in Top-quark Decay at the LHC
We explore the \Delta L=2 same-sign dilepton signal from top-quark decay via
a Majorana neutrino at the LHC in the top anti-top pair production samples. The
signature is same-sign dilepton plus multi-jets with no significant missing
energy. The most optimistic region lies where the Majorana neutrino mass is
between 15-65 GeV. For 300 fb^-1 integrated luminosity, it is possible to probe
S_{ij}, the effective mixing parameter, to order of 10^-5.Comment: 15 pages, 8 figure
Assessing the potential benefit of trade facilitation : A global perspective
The relationships between trade facilitation, trade flows, and capacity building are complex and challenging to assess, both empirically and in implementation. The authors measure and estimate the relationship between trade facilitation and trade flows across 75 countries in global trade, considering four important categories: port efficiency, customs environment, regulatory environment, and service sector infrastructure. A gravity model is employed that accounts for bilateral trade flows in manufactured goods in 2000-01 between the 75 countries, using traditional factors such as GDP, distance, language, and trade areas, and is augmented by the trade facilitation measures in the four categories for each country. The results suggest that both imports and exports for a country and for the world will increase with improvements in these trade facilitation measures. Potential gains from trade facilitation reforms are predicted by using the estimated parameters. The gains from trade facilitation are presented by comparing the gains across geographical regions and trade facilitation categories, and by domestic and partner improvements. The total gain in trade flow in manufacturing goods from trade facilitation improvements in all the four areas is estimated to be $377 billion. All regions gain in imports and exports. Most regions gain more in terms of exports than imports, in large part through increasing exports to the OECD market. The most important ingredient in getting these gains, particularly to the OECD market, is the country's own trade facilitation efforts. The detailed presentation of the results of the analysis may help inform policy decisions and capacity building choices.Transport and Trade Logistics,Trade Policy,Economic Theory&Research,Common Carriers Industry,Environmental Economics&Policies,TF054105-DONOR FUNDED OPERATION ADMINISTRATION FEE INCOME AND EXPENSE ACCOUNT,Common Carriers Industry,Transport and Trade Logistics,Trade Policy,Environmental Economics&Policies
Observing Signals of the Bulk Matter RS Model through Rare Decays of SUSY Particles
The bulk matter Randall-Sundrum (RS) model is a setup where Standard Model
(SM) matter and gauge fields reside in the bulk of 5D warped spacetime while
the Higgs field is confined on the IR brane. The wavefunctions of the 1st and
2nd generation matter particles are localized towards the UV brane and those of
the 3rd generation towards the IR brane, so that the hierarchical structure of
the Yukawa couplings arises geometrically without hierarchy in fundamental
parameters. This paper discusses an experimental test of this model in the case
where the Kaluza-Klein scale is far above the collider scale, but the model is
combined with 5D Minimal SUSY Standard Model (MSSM) and SUSY particles are in
the reach of collider experiments. A general SUSY breaking mass spectrum
consistent with the bulk matter RS model is considered: SUSY breaking sector
locates on the IR brane and its effects are mediated to 5D MSSM through a
hybrid of gravity mediation, gaugino mediation and gauge mediation. This paper
argues that it is possible to observe the signals of the bulk matter RS model
through rare decays of "almost SU(2) singlet mass eigenstates" that are induced
by flavor-violating gravity mediation contributions to matter soft SUSY
breaking terms
Running with Triplets: How Slepton Masses Change With Doubly-Charged Higgses
We examine the slepton masses of SUSYLR models and how they change due the
presence of light-doubly charged higgs bosons. We discover that the measurement
of the slepton masses could bound and even predict the value of the third
generation Yukawa coupling of leptons to the SU(2)_R Triplets. We also consider
the unification prospects for this model with the addition of left-handed, B -
L = 0 triplets--a model we call the Triplet Extended Supersymmetric Standard
Model (TESSM). Finally, we discuss the changes in the slepton masses due to the
presence of the SU(2)_L triplets.Comment: 20 pages, 6 figures, 4 table
Study to document low thrust trajectory optimization programs HILTOP and ASTOP
Detailed documentation of the HILTOP and ASTOP computer programs is presented along with results of the analyses of the possible extension of the HILTOP program and results of an extra-ecliptic mission study performed with HILTOP
Spatial determinants of local government action on climate change: an analysis of local authorities in England
The engagement of UK local authorities is vital if national government is to meet its
climate change commitments. However, with no mandatory targets at local government
level, other drivers must explain engagement. Using a Geographic Information System,
this study compares the spatial distribution of action on climate change based on past
actions and stated intentions to a suite of relevant independent variables. The Action
Index created is among the first to quantify climate change engagement beyond a simple
binary measure and provides a useful comparative study to recent work in the US. The
Index enables investigation of both mitigation and adaptation, which show different
trends in relation to some variables. The study shows that action is strongest where the
voting habits of the local population suggest environmental concern and where
neighbouring local authorities are also engaging in action on climate change. Physical
vulnerability to the effects of climate change is a motivator for action only where the
dangers are obvious. Action is less likely where other resource intensive issues such as
crime and housing exist within a local authority area
A Model for Neutrino and Charged Lepton Masses in Extra Dimensions
We propose a model with one large submm size extra dimension in which the
gravity and right-handed (RH) neutrino propagate, but the three Standard Model
(SM) families are confined to fat branes of TeV^(-1) size or smaller. The
charged leptons and the light neutrinos receive mass from the five dimensional
Yukawa couplings with the SM singlet neutrino via electroweak Higgs, while the
KK excitations of the SM singlet neutrino gets large TeV scale masses from the
five dimensional Yukawa coupling with an electroweak singlet Higgs. The model
gives non-hierarchical light neutrino masses, accommodate hierarchical charged
lepton masses, and naturally explain why the light neutrino masses are so much
smaller compared to the charged lepton masses. Large neutrino mixing is
naturally expected in this scenario. The light neutrinos are Dirac particles in
this model, hence neutrinoless double beta decay is not allowed. The model has
also several interesting collider implications and can be tested at the LHC.Comment: 11 pages, no figure
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