Predictions Of SU Research Articles

Predictions of SU(9) orbifold family unification

We study predictions of orbifold family unification models with SU(9) gauge group on a six-dimensional space–time including the orbifold T2/Z2, and obtain relations among sfermion masses in the supersymmetric extension of models. The models have an excellent feature that just three families of the standard model fermions exist in a pair of Weyl fermions in the 84 representation as four-dimensional zero modes, without accompanying any mirror particles.

Description of 160Dy nucleus by partial dynamical SU(3) symmetry

Abstract We considered the characteristic features of SU(3) partial dynamical symmetry in the interacting boson model framework to show the relevance of such intermediate symmetry structure in the nuclear spectroscopy of the 160Dy nucleus. The predictions of SU(3)-PDS for the energy spectrum and the transition probabilities were compared with the most recent experimental data and an acceptable degree of agreement was achieved.

Study of the π 0π 0η ′ final state in p̄p annihilation at rest

A partial wave analysis of p̄p → π 0π 0η ′ has been performed using the η′ → π 0π 0η and η′ → γγ decay modes. The data are dominated by an η′ recoiling against the ( ππ) S-wave. In addition, α 2 (1320) → η′π 0 is needed. There is evidence for contributions from α 0 (1450) → η′π 0 . The branching ratio of α 0 (1450) → η′π 0 with respect to ηπ 0 is consistent with the prediction of SU(3).

A novel approach to confront electroweak data and theory

A novel approach to study electroweak physics at one-loop level in generic SU(2)L×U(1)Y theories is introduced. It separates the 1-loop corrections into two pieces: process specific ones from vertex and box contributions, and universal ones from contributions to the gauge boson propagators. The latter are parametrized in terms of four effective form factors\(\bar e^2 (q^2 ), \bar s^2 (q^2 ), \bar g_Z^2 (q^2 )\) and\(\bar g_W^2 (q^2 )\) corresponding to the γγ, γZ,ZZ andWW propagators. Under the assumption that only the Standard Model contributes to the process specific corrections, the magnitudes of the four form factors are determined atq 2=0 and atq 2=m 2 Z by fitting to all available precision experiments. These values are then compared systematically with predictions of SU(2)L×U(1)Y theories. In all fits α s (m Z ) and\(\bar \alpha (m_Z^2 )\) are treated as external parameters in order to keep the interpretation as flexible as possible. The treatment of the electroweak data is presented in detail together with the relevant theoretical formulae used to interpret the data. No deviation from the Standard Model has been identified. Ranges of the top quark and Higgs boson masses are derived as functions of α s (m Z ) and\(\bar \alpha (m_Z^2 )\). Also discussed are consequences of the recent precision measurement of the left-right asymmetry at SLC as well as the impact of a top quark mass and an improvedW mass measurement.

Cosmological constraints and SU(5) supergravity grand unification

The predictions of SU(5) supergravity models with radiative breaking constrained by experimental proton decay bounds are discussed. It is shown that cosmological constraints further restrict the parameter space but can be satisfied for a wide range of parameters. It is also shown that no serious fine tuning problems (either at M SUSY or M GUT ) exist.

Low-energy excited states in124Te nucleus

The energies and intensities of the gamma transitions in the decay of124Sb are measured using a large-volume HPGe detector, with by far the best resolution, in singles and in coincidence with a NaI(Tl) detector. Gamma-gamma angular correlations are performed on six cascades. The results not only resolve several existing controversies about the level structure of124Te but also detect for the first time four new gamma transitions. Relative intensities, branching ratios, α(K) and logft values are calculated and multipolarities, spins and parities deduced. Comparison with the predictions ofSU(5) andO(6) limits of interacting boson approximation model seemed to favour the former approximation.

SU(3) predictions for nonleptonicT-meson decays

The predictions ofSU(3) are analyzed for the decays of theT-mesons (T0,T+,T s + ). Relations betweenT-meson decay rates are given. Some of these relations may provide important information for searching top mesons.

Distinguishability ofSU(2)×U(1)×U′(1) andSO(10) gauge models from the Weinberg-Salam model

The predictions ofSU(2)×U(1)×U′(1) andSO(10) gauge models for the asymmetry parametersA-,B-,CL andCR in the deep inelastic scattering of polarized electrons and positrons by unpolarized protons and deuterons are compared with those calculated in the Weinberg Salam model for different values ofy. The model based on,SU(2)×U(1)×U′(1) group has been found almost indistinguishable from the Weinberg Salam model with regard to the parametersA-,B- andCL (except forB- in the region 0≦y≦0.2) althoughCR exhibits marked distinguishability. TheSO(10) model, for certain choice of its model parameters, can be distinguished from the Weinberg Salam model through measurement of the asymmetry parameters for different values ofy.

The reaction π−p→K 0Λ0 up to 2375 MeV/ c: New results and analysis

New data are presented on the reaction π −p→K 0 Λ 0 at 13 incident momenta between 1395 and 2375 MeV/ c. A partial-wave analysis has been performed using these data and previous data at lower momenta. The resulting resonance parameters are in broad agreement with recent πN analyses and with the predictions of SU(6) W × O(3) for the couplings.

SU(3) Predictions for Charmed-Meson Decays

The predictions of SU(3) for charmed-meson decay are reanalyzed, allowing for expected new weak-mixing angles.

Alpha-particle stripping toNe21

From a study of the /sup 17/O(/sup 6/Li,d) reaction at 32 MeV, angular distributions and ..cap alpha..-particle spectroscopic strengths have been extracted for states below 4.6-MeV excitation in /sup 21/Ne. The 5/2/sup +/ state at 0.35 MeV is populated largely via L = 0, and fice states with J/sup ..pi../ from 1/2/sup +/ to 9/2/sup +/ largely via L = 2. These results are in reasonable agreement with predictions of SU(3) shell-model calculations and at the same time are suggestive of a simple weak-coupling picture. Observation of L = 0 for the transition to the 4.52-MeV level, previously assigned 3/2/sup +/ or 5/2/sup +/, allows a definite assignment of J/sup ..pi../ = 5/2/sup +/.

Dispersion Sum Rules forΣΛTransition Magnetic Moment

We consider sum rules for the process $\ensuremath{\pi}\ensuremath{\Lambda}\ensuremath{\rightarrow}\ensuremath{\pi}\ensuremath{\Sigma}$ obtained by equating the fixed-$t$ and the fixed-$u$ dispersion relations for the invariant amplitudes at a suitable point. The sum rules relate the transition magnetic moment for $\ensuremath{\Sigma}\ensuremath{\rightarrow}\ensuremath{\Lambda}+\ensuremath{\gamma}$ to the contributions from $s$-channel singularities. The results obtained are in agreement with the predictions of SU(3) and SU(6) symmetry.

An su (6) w fit to the negative parity baryon decay rates

We present a least squares fit to the experimental data on decays of negative parity baryon resonances into a pseudoscalar meson and either a J P = 1/2 + stable baryon or a J P = 3/2 + decuplet member. We find that the s-waves and d-waves are separately in good agreement with the predictions of SU (6) w ⊗ O(2) L z . Predictions are given regarding several as yet unobserved decay processes, and for those which concern hitherto undetected resonances, their possible detection is discussed.

Baryon exchange in the reaction K −p → Λω and K −n → Σω at 3 GeV/ c and [formula omitted] and [formula omitted] coupling constants

Differential cross sections are presented for the reactions K −p → Λω, K −p → Λϕ, K −n → Σ − ω and K −N → Σ − ϕ at 3 GeV/ c incident momentum. Significant backward peaks are observed in the reactions giving ω-meson production in contrast to the reactions with ϕ-meson production. The assumption that the backward peaks observed are due to nucleon exchange leads to a ratio of the coupling constants g Σ N K 2/g Λ N K 2 which is in disagreement with the prediction of SU(6) for this ratio.

Forward scattering in some two-body reactions involving [formula omitted] baryons and 0 − mesons at 3 GeV/ c

At 3 GeV/ c, forward differential cross sections and polarization distributions in two-body reactions involving 1 2 + baryons and 0 − mesons and charge or hypercharge exchange are compared with the predictions of SU(3) under the assumption that these reactions are dominated by exchange of members of the 1 − and 2 + meson octets. Good agreement is found independently for reactions in which strange and non-strange mesons are exchanged. The Reggeization of the t-channel amplitudes with parameters determined at high energy, when associated with a splitting of the trajectories corresponding to strange and non-strange exchanged mesons, leads to a good description of the forward scattering for all reactions.

Negative parity baryon resonances in the SU(6) symmetry

The decay ratios of negative parity baryon resonances are compared with prediction of SU W (6) symmetry by assigning these resonances to the 540 supermultiplet. Some “semiempirical” mass formulae are also investigated. It turns out that the present experimental data are not inconsistent with such an assignment. Nevertheless, we believe that not all the negative parity baryon resonances of spins 1/2−, 3/2−, 5/2− fit into the 540-plet without contradicting experimental values.

Low-energy photopion production SU(6) and the panofsky ratio

It is argued that the main sources of uncertainty in low-energy photopion production occur in the multipoles M1−(1) + 3M1−(0), E1+(1), E1+(3), E1+(1)+#E0+(0) and E0+(3). Parametric forms based on general assumptions are devised for these multipoles and a satisfactory fit is obtained to all the data up to Eγ1ab = 440 MeV. The lack of good π) data outside the threshold region is stressed and the multipoles compared to various theoretical predictions. In particular, the results for E1+(3) favour the solution of Finkler compared to that of Rollnik et al., and good agreement is found with the prediction of SU(6) and other symmetries of resonance. However, the latter are less successful with the magnetic transition M1+(3). Finally a careful analysis of the threshold region for π+ production is carried out, and the Panofsky ratio problem reconsidered. We find the scattering length combination a1−a3 = 0.254 ± 0.013, and this is compared with the results obtained by other methods.

Comparison of a New SU3Prediction with Experiment

S>A rule for reaction processes is proposed considering processes of two types: meson + proton yields baryon resonance + meson, and meson + proton yields baryon resonance + vector meson. Data for various reactions are compiled, and the reaction predictions of SU(3) are discussed. 22 references. (R. E. U.)