Robert J. Oakes

SU(2) × SU(2) breaking and the Cabibbo angle

Abstract In a recent investigation of the transformation properties under chiral SU(3) × SU(3) of the hadron energy density H ( X ) Gell-Mann, Oakes and Renner have assumed the form H = H − H 0 − CU 8 where H is SU(3) × SU(3) invariant while U 0 and U 8 belong to the representation (3 ∗ , 3) + (3, 3 ∗ ) and have found the constant C to be near the value − 2 , which corresponds to the limit in which the subgroup SU(2) × SU(2) remains an exact symmetry with the conservation of the axial-vector currents being realized through massless pions. Here we pursue the question of the SU(3) × SU(3) transformation properties of H ( X ) further and investigate the deviations from the limiting case C = − 2 under specific assumptions regarding the origin of the breaking of SU(2) × SU(2). Our main assumption is that chiral SU(2) × SU(2) breaking in strong interactions (C ≠ − 2 , m π ≠ 0) and the non-conservation of strangeness in weak interactions (Cabibbo angle θ ≠ 0) derive from a common origin. We find that all the small parameters C + 2 , m π /m K and θ are simply related to each other and that the hadron energy density H ( X ) constains in addition a term U 3 , belonging to the same (3 ∗ , 3) + (3, 3 ∗ ) representation of determined strength which also breaks SU(2) and thus contributes to certain mass shifts, e.g., K + − K o , along with the usual electromagnetic interaction. Numerically the comparison with experiment is favourable lending support to our assumptions regarding the breaking of SU(2) × SU(2).

QCD corrections to t→W++b

The {ital O}({alpha}{sub {ital s}}) QCD corrections to the process {ital t}{r arrow}{ital W}{sup +}{ital b} are calculated in the standard model for a heavy top quark. For {ital m}{sub {ital W}}/{ital M}{sub {ital t}}{lt}0.8, the corrections reduce the partial width by 10% relative to the tree-level result. This reduction of the top-quark width enhances the signal for {ital t{bar t}} bound-state resonances near threshold in {ital e}{sup +}{ital e{minus}} collisions, studied recently by Strassler and Peskin.

B meson dileptonic decays in the next-to-minimal supersymmetric model with a light CP-odd Higgs boson

In the next-to-minimal supersymmetric model (NMSSM) a light CP-odd Higgs boson is so far allowed by current experiments, which, together with a large tan β, may greatly enhance the rare dileptonic decays B → Xsll and Bs → l+l−γ. We examine these decays paying special attention to the new operator allowed by the light CP-odd Higgs boson. We find that in the parameter space allowed by current experiments like LEP II and b → sγ, the branching ratios of these rare decays can be greatly enhanced and thus the existing experimental data on B → Xsμμ can further stringently constrain the parameter space (especially the region with a super-light CP-odd Higgs boson and large tan β). In the surviving parameter space we give the predictions for other dileptonic decay branching ratios and also show the results for the forward-backward asymmetry. PACS numbers: 14.80.Cp, 13.85.Qk,12.60.Jv

Comparative study of the hadronic production of B c mesons

A comparative study of the full {alpha}{sup 4}{sub {ital s}} perturbative QCD calculation of the hadronic production of the {ital B}{sub {ital c}} and {ital B}{sub {ital c}}{sup {asterisk}} mesons and the fragmentation approximation is presented. We examined the various subprocesses in detail and the distribution {ital C}({ital z}), where {ital z} is twice the fraction of the {ital B}{sub {ital c}} or {ital B}{sub {ital c}}{sup {asterisk}} meson energy in the center of mass of the subprocess, which proved insightful and revealed the importance of certain nonfragmentation contributions. We concluded that the condition for the applicability of the fragmentation approximation in hadronic collisions is that the transverse momentum {ital P}{sub {ital T}} of the produced {ital B}{sub {ital c}} and {ital B}{sub {ital c}}{sup {asterisk}} be much larger than the mass of the {ital B}{sub {ital c}} meson: i.e., {ital P}{sub {ital T}}{gt}{ital M}{sub {ital B}{sub {ital c}}}. Numerical results for the cross sections at the Fermilab Tevatron are also presented using updated parton distribution functions with various kinematic cuts. {copyright} {ital 1996 The American Physical Society.}

Next-to-leading order QCD predictions for graviton and photon associated production in the Large Extra Dimensions model at the LHC

We present the calculations of the complete next-to-leading order (NLO) QCD corrections to the inclusive total cross sections for the Kaluza-Klein (KK) graviton and photon associated production process pp{yields}{gamma}G{sub KK}+X in the large extra dimensions model at the LHC. We show that the NLO QCD corrections in general enhance the total cross sections and reduce the dependence of the total cross sections on the factorization and renormalization scales. When jet veto is considered, the NLO corrections reduce the total cross sections. We also calculate some important differential cross sections for this process at NLO: the missing transverse momentum distribution, the transverse momentum distribution, and the pseudorapidity distribution of photon.

SU(2) × SU(2) symmetry breaking and η → 3π

Abstract The hadron energy density discussed in a previous investigation of the relation between the breaking of chiral SU(2) × SU(2) symmetry and the Cabibbo angle θ is shown to yield η → πo πo πo and η → → π+ πo π− decay amplitudes which are in reasonably good agreement with experiment.

Supersymmetric effects in top quark decay into polarized

We investigate the one-loop supersymmetric QCD (SUSY-QCD) and electroweak (SUSY-EW) corrections to the top quark decay into a b quark and a longitudinal or transverse W boson. The corrections are presented in terms of the longitudinal ratio Gamma(t-->W(L)b)/Gamma(t-->Wb) and the transverse ratio Gamma(t-->W(-)b)/Gamma(t-->Wb). In most of the parameter space, both SUSY-QCD and SUSY-EW corrections to these ratios are found to be less than 1% in magnitude and they tend to have opposite signs. The corrections to the total width Gamma(t-->Wb) are also presented for comparison with the existing results in the literature. We find that our SUSY-EW corrections to the total width differ significantly from previous studies: the previous studies give a large correction of more than 10% in magnitude for a large part of the parameter space while our results reach only few percent at most.

W

We analyze the asymmetry in the partial widths for the decays

boson

B^{\pm} \to M {\bar M} \pi^{\pm}

The CP violating asymmetry in decays

(