14539980
Mass matrix ansatz for degenerate neutrinos consistent with solar and atmospheric neutrino data
We suggest mass matrices for neutrinos and charged leptons that can explain solar and atmospheric neutrino data. The resulting flavor mixing matrix Vν has a property that (Vν)13=0, thus making νe↔νμ and νμ↔ντ oscillations to be effectively a two-channel problem. Phenomenological consequences of the lepton mass matrix ansatze are consistent with the current data on various type of neutrino oscillation experiments except the LSND measurement. Three neutrinos, being almost degenerate with ∑|mνi|≲1 eV, can be a part of hot dark matter without any conflict with the constraint from neutrinoless double beta decay experiments. The νμ↔ντ oscillation, sin22θμτ, is predicted to be 0.86–0.97 with Δm2μτ≃2×10−3eV2, which is consistent with the atmospheric neutrino data and can be tested further at the planned MINOS and K2K experiments searching for νμ→ντ oscillation.
119883211
Conflicts between B-violating phenomena in supergravity models
Abstract We show that there is an incompatibility between matter stability and cosmological baryon production in standard N = 1 supergravity models. This discrepancy emerges from the bound on the reheating temperature T rh ⩽ 10 10 GeV which comes from the restriction on the gravitino decay after inflation. Some weird possibilities to bypass the controversy are also analyzed.
119316975
GMSB at a stable vacuum and MSSM without exotics from heterotic string
Abstract We show that it is possible to introduce the confining hidden sector gauge group SU ( 5 ) ′ with the chiral matter 10 0 ′ plus 5 ¯ 0 ′ , which are neutral under the standard model gauge group, toward a gauge mediated supersymmetry breaking (GMSB) in a Z 12 − I orbifold compactification of E 8 × E 8 ′ heterotic string. Three families of MSSM result without exotics. We also find a desirable matter parity P (or R-parity) assignment. We note that this model contains the spectrum of the Lee–Weinberg model which has a nice solution of the μ problem.
18138135
Neutrino masses from discrete gauge symmetries
Abstract We investigate a model with an extra Z 2 gauge symmetry in the Standard Model. The symmetry gives a structure to the mass matrix for the neutrinos. With two extra Higgs singlets and two extra singlet right-handed neutrinos we can build a model that fits the requirements of the MSW solution of the Solar neutrino problem. With a third singlet right-handed neutrino it is also possible to have a 10 eV neutrino.
15739165
SO(10)-like Superstring Standard Model with R-parity from the Heterotic String
We construct a supersymmetric standard model in the context of the Z_{12-I} orbifold compactification of the E_8 x E_8' heterotic string theory. The gauge group is SU(3)_c x SU(2)_L x U(1)_Y x U(1)^4 x [SO(10) x U(1)^3]' with sin^2\theta_W = 3/8. We obtain three families of SO(10) spinor-like chiral matter states, and Higgs doublets. All other extra states are exactly vector-like under the standard model gauge symmetry. There are numerous standard model singlets, many of which get VEVs such that only the standard model gauge symmetry survives and desired Yukawa couplings can be generated at lower energies. In particular, all vector-like exotic states achieve superheavy masses and the R-parity can be preserved.
14574575
Effective Gauss-Bonnet interaction in Randall-Sundrum compactification
The effective gravitational interaction below the Planck scale in the Randall-Sundrum world is shown to be the Gauss-Bonnet term. In this theory we find that there exists another static solution with a positive bulk cosmological constant. Also, there exist solutions for a positive visible sector cosmological constant, which is needed for a later Friedmann-Robertson-Walker universe.
814570
Electroweak contributions to squark pair production at the CERN LHC
In this paper we compute electroweak contributions to the production of squark pairs at hadron colliders. These include the exchange of electroweak gauge bosons in the s-channel as well as electroweak gaugino exchange in the t- and/or u-channel. In many cases these can interfere with the dominant QCD contributions. As a result, we find sizable contributions to the production of two SU(2) doublet squarks. At the LHC, they amount to 10% to 20% for typical mSUGRA (or CMSSM) scenarios, but in more general scenarios they can vary between -40% and +55%, depending on size and sign of the SU(2) gaugino mass. The electroweak contribution to the total squark pair production rate at the LHC is about 3.5 times smaller.
118182564
A Simple Baryon Triality Model for Neutrino Masses
We make a simple ansatz for the supersymmetric lepton-number violating Yukawa couplings, by relating them to the corresponding Higgs Yukawa couplings. This reduces the free B$_3$ parameters from 36 to 6. We fit these parameters to solve the solar and atmospheric neutrino anomalies in terms of neutrino oscillations. The resulting couplings are consistent with the stringent low-energy bounds. We investigate the resulting LHC collider signals for a stau LSP scenario.
119300805
Light stop phenomenology
We consider the discovery potential of light stops in the MSSM at the LHC. Here, we assume that the lightest neutralino is the LSP and that the lighter stop i s the NLSP. Direct stop pair production is difficult to probe in scenarios with a small mass splitting between the stop and a neutralino. We discuss two different search channels: the monojet and the two b‐flavoured jets and large missing transverse energy signature. We present the discovery reach in the stop‐neutralino mass plane for both channels. The latter process is sensitive to the stop‐h iggsino‐b quark coupling. This allows us to test a supersymmetry relation involving superpotential couplings. We briefly comment on the possible precision with which the coupling can be measured.
119291744
Neutrino masses and mixings in the baryon triality constrained minimal supersymmetric standard model
We discuss how the experimental neutrino oscillation data can be realized in the framework of the baryon triality ($B_3$) constrained supersymmetric Standard Model (cSSM). We show how to obtain phenomenologically viable solutions, which are compatible with the recent WMAP observations. We present results for the hierarchical, inverted and degenerate cases which illustrate the possible size and structure of the lepton number violating couplings. We work with a new, as yet unpublished version of SOFTSUSY, where we implemented full one--loop neutrino masses. Finally, we shortly discuss some phenomenological implications at the LHC.
1556990
Optimizing interferometer experiments for CMB B mode measurement
The sensitivity of interferometers with linear polarizers to the CMB E and B mode are variant under the rotation of the polarizer frame, while interferometer with circular polarizers are equally sensitive to E and B mode. We present analytically and numerically that the diagonal elements of window functions for CMB E/B power spectra are maximized in interferometric measurement of linear polarization, when the polarizer frame is in certain rotation from the associated baseline. We also present the simulated observation to show that the 1σ errors on E/B mode power spectrum estimation are variant under the polarizer frame rotation in the case of linear polarizers, while they are invariant in the case of circular polarizers. Simulation of the configuration similar to the DASI shows that minimum 1σ error on B mode in interferometer measurement with linear polarizers is 26 per cent of that in interferometric measurement with circular polarizers. The simulation also shows that the E/B mixing in interferometer measurement with linear polarizers can be as low as 23 per cent of that in interferometric measurement with circular polarizers. It is not always possible to physically align the polarizer frame with all the associated baselines in the case of an interferometer array (N>2). There exist certain linear combinations of visibilities, which are equivalent to visibilities of the optimal polarizer frame rotation. We present the linear combinations, which enables B mode optimization for an interferometer array (N>2).