Biomedical subjects

C Kolda

Publications and source records attributed to C Kolda.

10 recordsLinked to original sources

PubMed2003

Bd-->phi KS CP asymmetries as an important probe of supersymmetry.

The decay B(d)-->phi K(S) is a special probe of physics beyond the standard model (SM), since it has no SM tree level contribution. Motivated by recent data suggesting a deviation from the SM for its time-dependent CP asymmetry, we examine supersymmetric explanations. Chirality preserving contributions are generically small, unless gluino is relatively light. Higgs contributions are also too small to explain a large asymmetry. Chirality flipping LR and RL gluino contributions actually can provide sizable effects without conflict with all related results. We discuss how various insertions can be distinguished, and argue the needed sizes of mass insertions are reasonable.

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PubMed2000

New perspective on cosmic coincidence problems

Cosmological data suggest that we live in an interesting period in the history of the universe when rho(Lambda) approximately rho(M) approximately rho(R). The occurrence of any epoch with such a "triple coincidence" is puzzling, while the question of why we happen to live during this special epoch is the "Why now?" problem. We introduce a framework which makes the triple coincidence inevitable; furthermore, the "Why now?" problem is transformed and greatly ameliorated. The framework assumes that the only relevant mass scales are the electroweak scale M(EW), and the Planck scale M(Pl) and requires rho(1/4)(Lambda) approximately M(2)(EW)/M(Pl) parametrically. Assuming that the true vacuum energy vanishes, we present a simple model, where a false vacuum energy yields a cosmological constant of this form.

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PubMed2000

Higgs-mediated B0 --> &mgr;(+)&mgr;(-) in minimal supersymmetry

We demonstrate a new source for flavor-changing neutral currents within the minimal supersymmetric standard model. At moderate to large tanbeta, it is no longer possible to diagonalize the masses of the quarks in the same basis as their Yukawa couplings. This generates flavor-violating couplings of the form &bmacr;(R)d(L)straight phi and &bmacr;(R)s(L)straight phi where straight phi is any of the three neutral, physical Higgs bosons. These new couplings lead to rare processes in the B system such as B0-->&mgr;(+)&mgr;(-) and B0-&Bmacr;(0) mixing. We show that the latter are anomalously suppressed, while the former is in the experimentally interesting range, with an observable signal possible at Run II of the Tevatron if m(A) less, similar400-700 GeV.

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PubMed1996