Multiplicative Conservation of Baryon Number and Baryogenesis

In the canonical seesaw mechanism of neutrino mass, lepton number is only multiplicatively conserved, which enables the important phenomenon of leptogenesis to occur, as an attractive explanation of the present baryon asymmetry of the Universe. A parallel possibility, hitherto unrecognized, also holds for baryon number and baryogenesis. This new idea is shown to be naturally realized in the context of a known supersymmetric string-inspired extension of the Standard Model, based on E(6) particle content, and having an extra U(1)_N gauge symmetry. Within this framework, two-loop radiative neutrino masses are also possible, together with a new form of very long-lived matter.Comment: 9 pages, 4 figures, 3 table

Revelations of the E_6/U(1)_N Model: Two-Loop Neutrino Mass and Dark Matter

The E_6/U(1)_N gauge extension of the Supersymmetric Standard Model, first proposed by Ma, is shown to have exactly the requisite ingredients to realize the important new idea that dark matter is the origin of neutrino mass. With the implementation of a discrete Z_2 X Z_2 symmetry, and particle content given by three {27} representations of E_6, neutrino masses are naturally generated in two loops, with candidates of dark matter in the loops. All particles of this model are expected to be at or below the TeV scale, allowing them to be observable at the LHC.Comment: 10 pages, 3 figure

Are joint torque models limited by an assumption of monoarticularity?

This study determines whether maximal voluntary ankle plantar flexor torque could be more accurately represented using a torque generator that is a function of both knee and ankle kinematics. Iso velocity and isometric ankle plantar flexor torques were measured on a single participant for knee joint angles of 111° to 169° (approximately full extension) using a Contrex M J dynamometer. Maximal voluntary torque was represented by a 19-parameter two-joint function of ankle and knee joint angles and angular velocities with the parameters determined by minimizing a weighted root mean square difference between measured torques and the two-joint function. The weighted root mean square difference between the two-joint function and the measured torques was 10 N-m or 3% of maximum torque. The two-joint function was a more accurate representation of maximal voluntary ankle plantar flexor torques than an existing single-joint function where differences of 19% of maximum torque were found. It is concluded that when the knee is flexed by more than 40°, a two-joint representation is necessary

CKM and Tri-bimaximal MNS Matrices in a SU(5) x (d)T Model

We propose a model based on SU(5) x {}^{(d)}T which successfully gives rise to near tri-bimaximal leptonic mixing as well as realistic CKM matrix elements for the quarks. The Georgi-Jarlskog relations for three generations are also obtained. Due to the {}^{(d)}T transformation property of the matter fields, the b-quark mass can be generated only when the {}^{(d)}T symmetry is broken, giving a dynamical origin for the hierarchy between m_{b} and m_{t}. There are only nine operators allowed in the Yukawa sector up to at least mass dimension seven due to an additional Z_{12} x Z'_{12} symmetry, which also forbids, up to some high orders, operators that lead to proton decay. The resulting model has a total of nine parameters in the charged fermion and neutrino sectors, and hence is very predictive. In addition to the prediction for \theta_{13} \simeq \theta_{c}/3 \sqrt{2}, the model gives rise to a sum rule, \tan^{2}\theta_{\odot} \simeq \tan^{2} \theta_{\odot, \mathrm{TBM}} - {1/2} \theta_{c} \cos\beta, which is a consequence of the Georgi-Jarlskog relations in the quark sector. This deviation could account for the difference between the experimental best fit value for the solar mixing angle and the value predicted by the tri-bimaximal mixing matrix.Comment: 11 pages; v2: additional references added; minor modifications made; conclusion unchanged; v3: version to appear in Phys. Lett.

An isovelocity dynamometer method to determine monoarticular and biarticular muscle parameters

This study aimed to determine whether subject-specific individual muscle models for the ankle plantar flexors could be obtained from single joint isometric and isovelocity maximum torque measurements in combination with a model of plantar flexion. Maximum plantar flexion torque measurements were taken on one subject at six knee angles spanning full flexion to full extension. A planar three-segment (foot, shank and thigh), two muscle (soleus and gastrocnemius) model of plantar flexion was developed. Seven parameters per muscle were determined by minimizing a weighted root mean square difference (wRMSD) between the model output and the experimental torque data. Valid individual muscle models were obtained using experimental data from only two knee angles giving a wRMSD score of 16 N m, with values ranging from 11 to 17 N m for each of the six knee angles. The robustness of the methodology was confirmed through repeating the optimization with perturbed experimental torques (±20%) and segment lengths (±10%) resulting in wRMSD scores of between 13 and 20 N m. Hence, good representations of maximum torque can be achieved from subject-specific individual muscle models determined from single joint maximum torque measurements. The proposed methodology could be applied to muscle-driven models of human movement with the potential to improve their validity

Light Charged Higgs Bosons in Supersymmetric Models

We point out that present experimental limits from searches for neutral Higgs bosons at LEP already imply stringent lower bounds on the mass of the charged Higgs boson in the Minimal Supersymmetric Standard Model (MSSM); these bounds are especially severe for low values of \tanb (\tanb \leq 3), where the $H^+ \bar{t} b$ coupling is large. However, these indirect constraints are much weaker in simple extensions of the MSSM Higgs sector involving the introduction of an extra U(1) gauge group or an extra $SU(2) \times U(1)_Y$ Higgs singlet field; in the latter case charged Higgs bosons can even be light enough to be pair produced at LEP.Comment: LaTeX with equation.sty, 3 PS figures. Version to appear in PLB: Added one paragraph concerning charged Higgs searches at the Tevatro

SU(5) Completion of the Dark Scalar Doublet Model of Radiative Neutrino Mass

Adding a second scalar doublet (eta^+,eta^0) and three neutral singlet fermions N_{1,2,3} to the Standard Model of particle interactions with a new Z_2 symmetry, it has been shown that eta^0_R or eta^0_I is a good dark-matter candidate and seesaw neutrino masses are generated radiatively. A minimal extension of this new idea is proposed to allow for its SU(5) completion. Supersymmetric unification is then possible, and leptoquarks of a special kind are predicted at the TeV scale.Comment: 6 pages, 2 figures, 1 tabl

Extended Hylleraas three-electron integral

A closed form expression for the three-electron Hylleraas integral involving the inverse quadratic power of one inter-particle coordinate is obtained, and recursion relations are derived for positive powers of other coordinates. This result is suited for high precision calculations of relativistic effects in lithium and light lithium-like ions.Comment: Submited to Phys. Rev.

SU(3) family symmetry and neutrino bi-tri-maximal mixing

The observed large mixing angles in the lepton sector may be the first signal for the presence of a non-Abelian family symmetry. However, to obtain the significant differences between the mixing of the neutrino and charged fermion sectors, the vacuum expectation values involved in the breaking of such a symmetry in the two sectors must be misaligned. We investigate how this can be achieved in models with an SU(3) family symmetry consistent with an underlying GUT. We show that such misalignment can be achieved naturally via the see-saw mechanism. We construct a specific example in which the vacuum (mis)alignment is guaranteed by additional symmetries. This model generates a fermion mass structure consistent with all quark and lepton masses and mixing angles. Neutrino mixing is close to bi-tri-maximal mixing.Comment: References added; typos correcte

Tri-bimaximal Neutrino Mixing from A(4) and \theta_{13} \sim \theta_C

It is a common believe that, if the Tri-bimaximal mixing (TBM) pattern is explained by vacuum alignment in an A(4) model, only a very small reactor angle, say \theta_{13} \sim \lambda^2_C being \lambda_C \equiv \theta_C the Cabibbo angle, can be accommodated. This statement is based on the assumption that all the flavon fields acquire VEVs at a very similar scale and the departures from exact TBM arise at the same perturbation level. From the experimental point of view, however, a relatively large value \theta_{13} \sim \lambda_C is not yet excluded by present data. In this paper, we propose a Seesaw A(4) model in which the previous assumption can naturally be evaded. The aim is to describe a \theta_{13} \sim \lambda_C without conflicting with the TBM prediction for \theta_{12} which is rather close to the observed value (at \lambda^2_C level). In our model the deviation of the atmospherical angle from maximal is subject to the sum-rule: \sin ^2 \theta_{23} \approx 1/2 + \sqrt{2}/2 \sin \delta \cos \theta_{13} which is a next-to-leading order prediction of our model.Comment: 16 pages, revised, typos corrected, references adde