相关论文: Fourth Generation b-prime decays into b + Higgs

We study various FCNC involving heavy quarks in the Standard Model (SM) with a sequential fourth generation. After imposing $B\to X_s\gamma$, $B\to X_sl^+l^-$ and $Z\to b\bar{b}$ constraints, we find ${\cal B}(Z\to s\bar{b}+\bar{s}b)$ can…

We present the results of a search for pair production of a fourth-generation charge -1/3 quark (b') in sqrt(s)=1.8 TeV ppbar collisions using 88 pb^(-1) of data obtained with the Collider Detector at Fermilab. We assume that both quarks…

We calculate four-fermion decays of a Higgs boson via $WW$ and/or $ZZ$ intermediate states for Higgs masses below $m_W$. We examine models with a doubly-charged Higgs boson $H^{++}$ and show that the four-fermion decay is the dominant mode…

It is often stated that elimination of tree-level flavor-changing neutral currents in multi-Higgs models requires that all fermions of a given charge to couple to the same Higgs boson. A counterexample was provided by Abe, Sato and Yagyu in…

We propose the rare SM Higgs decay $H\to b\bar b b\bar b$ as a probe of the structure of Higgs interactions with bottom quarks and gauge bosons, and as a baseline for searches for new physics producing four-bottom final states in Higgs…

A sequential fourth generation is still viable, but the t' and b' quarks are constrained to be not too far apart in mass. The t'{\to}bW and b'{\to}tW decay channels are still being pursued at the Tevatron, which would soon be surpassed by…

Recent results from the DELPHI collaboration led us to review the present bounds on the b' quark mass. We use all available experimental data for m_b' > 96 GeV to constrain the b' quark mass as a function of the Cabibbo-Kobayashi-Maskawa…

In the scenario with Z mediated flavor changing neutral current occurring at the tree level due to the addition of a vector-like isosinglet down-type quark d' to the SM particle spectrum, we perform a chi square fit using the flavor physics…

A search for neutral Higgs bosons decaying into a b-bbar quark pair and produced in association with at least one additional b quark is presented. This signature is sensitive to the Higgs sector of the minimal supersymmetric standard model…

Within the Standard model with the 4th generation quarks b' and t' we have analyzed CP-violating flavor changing neutral current processes t -> cX; b'-> sX, b'-> bX,t'-> cX, and t'-> tX, with X=Z,H,gamma,g, by constructing and employing…

We study the decays of heavy chiral (t', b') quarks in a four-generation extension of the Standard Model. If the difference between the t' and b' masses is smaller than the W mass, as favored by precision electroweak measurements, then the…

The existing bounds from CDF on the masses of the fourth generation quarks, t' and b', are reexamined. The bound of 256 GeV on the t' mass assumes that the primary decay of the t' is into q+W, which is not the case for a substantial region…

A search for a massive resonance W' decaying into a W and a Higgs boson in the l nu b anti-b (l = e, mu) final state is presented. Results are based on data corresponding to an integrated luminosity of 19.7 inverse femtobarns of…

We report on a search for pair production of a fourth generation charge -1/3 quark (b') in pbar p collisions at sqrt(s) = 1.8 TeV at the Fermilab Tevatron using an integrated luminosity of 93 pb^-1. Both quarks are assumed to decay via…

We study the decay width of the inclusive process b --> s g g in the two Higgs doublet model with three level flavor changing neutral currents (model III). We analyse the dependencies of the differential decay width to the s quark energy…

In this letter we demonstrate a new source for large flavor-changing neutral currents within the minimal supersymmetric standard model. At moderate to large tan(beta), it is no longer possible to diagonalize the masses of the quarks in the…

Direct and indirect searches of the Higgs boson suggest that 113 GeV $\lesssim m_H \lesssim$ 170 GeV is likely. With the LEP era over and the Tevatron Run II search via $p\bar p \to WH+X$ arduous, we revisit a case where $WH$ or $ZH +$ jets…

Present limits on chiral fourth-generation quark masses $m_{b'}$ and $m_{t'}$ are broadly generalized and strengthened by combining both $t'$ and $b'$ decays and considering the full range of $t'$ and $b'$ flavor-mixing scenarios (with the…

We determine the masses of the sequential fourth generation quarks $b'$ and $t'$ in the extension of the Standard Model by solving the dispersion relations associated with the mixing between the neutral states $Q\bar q$ and $\bar Qq$, $Q$…

Recent fits of electroweak precision data to the Standard Model (SM) with a 4th sequential family (SM4) point to a possible "three-prong composite solution": (1) the Higgs mass is at the TeV-scale, (2) the masses of the 4th family quarks…