Related papers: Direct Mass Limits for Chiral Fourth-Generation Qu…
We present a reanalysis of CDF data to extend limits on individual fourth-generation quark masses from particular flavor-mixing rates to the entire space of possible mixing values. Measurements from CDF have set individual limits on masses,…
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…
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 this work we present limits on a sequential down-type quark, b', based on the most recent DELPHI data. Using all available experimental data for m_b' > 96 GeV we conclude that a sequential four generations model is far from being…
We study the one-loop contribution of the down-type quark of the standard model-like fourth generation (b') on the top quark electric dipole moment. Using the known limits on the top quark electric dipole moments, we place limits on the b'…
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 $\bar Qq$, $Q$…
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…
We investigate the $\epsilon^{\prime} /\epsilon$ for $K\to \pi\pi$ in a sequential fourth generation model. By giving the basic formulae for $\epsilon^{\prime}/\epsilon$ in this model, we analyze the numerical results which are dependent of…
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…
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 report the most restrictive direct limits on masses of fourth-generation down-type quarks $b^{\prime}$, and quark-like composite fermions ($B$ or $T_{5/3}$), decaying promptly to $t W^{\mp}$. We search for a significant excess of events…
We investigate the mass differences $\Delta M_{B_{d,s}}$ in the mixing $B^0_{d,s}-\bar B^0_{d,s}$ with a new up-like quark $t^{\prime}$ in the sequential fourth generation model. We give the basic formulae for $\Delta M_{B_{d,s}}$ in this…
We report the most sensitive direct search for pair production of fourth-generation bottom-like chiral quarks ($b'$) each decaying promptly to $tW$. We search for an excess of events with an electron or muon, at least five jets (one…
If a fourth generation quark exists whose mass is below 255 GeV, then the only two-body charged current decay, b'-->cW, is doubly-Cabibbo suppressed. For this reason, CDF has searched for the one-loop neutral current decay b' --> bZ,…
We select sum rules from which one can extract directly reliable limits on the size of the chiral symmetry breaking light quark condensate $<\bar\psi\psi>$. Combined results from the nucleon and $B^*-B$ mass-splitting sum rules give a…
Results are presented from a search for a fourth generation of quarks produced singly or in pairs in a data set corresponding to an integrated luminosity of 5 inverse femtobarns recorded by the CMS experiment at the LHC in 2011. A novel…
In the light of the LHC, we revisit the implications of a fourth generation of chiral matter. We identify a specific ensemble of particle masses and mixings that are in agreement with all current experimental bounds as well as minimize the…
We perform an exploratory study of the allowed parameter range for the CKM-like mixing of hypothetical quarks of a fourth generation. As experimental constraints we use the tree-level determinations of the 3 $\times$ 3 CKM elements and FCNC…
We show that a fourth family of quarks with $m_{t'}$ in the range of (400 - 600) GeV provides a rather simple explanation for the several indications of new physics that have been observed involving CP asymmetries of the b-quark. The…
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…