Kaluza-Klein Dark Matter

We propose that cold dark matter is made of Kaluza-Klein particles and explore avenues for its detection. The lightest Kaluza-Klein state is an excellent dark matter candidate if standard model particles propagate in extra dimensions and Kaluza-Klein parity is conserved. We consider Kaluza-Klein gauge bosons. In sharp contrast to the case of supersymmetric dark matter, these annihilate to hard positrons, neutrinos and photons with unsuppressed rates. Direct detection signals are also promising. These conclusions are generic to bosonic dark matter candidates.Comment: 4 pages, 3 figures, discussion of spin-independent cross section clarified, references added, published versio

CP Violation from Slepton Oscillations at the LHC and NLC

In supersymmetric theories the charged sleptons of different generations may oscillate amongst themselves while they decay. In the case of three generation oscillations, superpartner production at the LHC and NLC may lead to an observable $CP$-violating signal $N(e^+\mu^-) - N(\mu^+e^-)$. This signal is proportional to a $CP$-violating invariant of the slepton mass matrix, $\widetilde{J}$, which is not constrained by searches for the electric dipole moment of the electron. The sensitivity of the LHC and NLC to this signal is highly dependent on superpartner masses, but $\widetilde{J}$ may be probed to a level of $10^{-3}$. Observation of the $CP$-violating signal would imply a definite structure for the slepton mass matrices and have strong implications for models of flavor and SUSY breaking.Comment: 37 pages, REVTeX, 7 figure

Probing Lepton Flavor Violation at Future Colliders

Supersymmetric theories with significant lepton flavor violation have $\tilde{e}$ and $\tilde{\mu}$ nearly degenerate. In this case, pair production of $\tilde{e}^+ \tilde{e}^-$ and $\tilde{\mu}^+ \tilde{\mu}^-$ at LEPII and at the Next Linear Collider leads to the phenomenon of slepton oscillations, which is analogous to neutrino oscillations. The reach in $\Delta m^2$ and $\sin^2 2 \theta$ gives a probe of lepton flavor violation which is significantly more powerful than the current bounds from rare processes, such as $\mu \to e\gamma$. Polarizable $e^-$ beams and the $e^-e^-$ mode at the NLC are found to be promising options.Comment: 10 pages, 3 figures, RevTeX, minor corrections, published versio

Doping and temperature dependence of electron spectrum and quasiparticle dispersion in doped bilayer cuprates

Within the t-t'-J model, the electron spectrum and quasiparticle dispersion in doped bilayer cuprates in the normal state are discussed by considering the bilayer interaction. It is shown that the bilayer interaction splits the electron spectrum of doped bilayer cuprates into the bonding and antibonding components around the $(\pi,0)$ point. The differentiation between the bonding and antibonding components is essential, which leads to two main flat bands around the $(\pi,0)$ point below the Fermi energy. In analogy to the doped single layer cuprates, the lowest energy states in doped bilayer cuprates are located at the $(\pi/2,\pi/2)$ point. Our results also show that the striking behavior of the electronic structure in doped bilayer cuprates is intriguingly related to the bilayer interaction together with strong coupling between the electron quasiparticles and collective magnetic excitations.Comment: 9 pages, 4 figures, updated references, added figures and discussions, accepted for publication in Phys. Rev.

Precambrian Animal Life: Probable Developmental and Adult Cnidarian Forms from Southwest China

The evolutionary divergence of cnidarian and bilaterian lineages from their remote metazoan ancestor occurred at an unknown depth in time before the Cambrian, since crown group representatives of each are found in Lower Cambrian fossil assemblages. We report here a variety of putative embryonic, larval, and adult microfossils deriving from Precambrian phosphorite deposits of Southwest China, which may predate the Cambrian radiation by 25–45 million years. These are most probably of cnidarian affinity. Large numbers of fossilized early planula-like larvae were observed under the microscope in sections. Though several forms are represented, the majority display remarkable conformity, which is inconsistent with the alternative that they are artifactual mineral inclusions. Some of these fossils are preserved in such high resolution that individual cells can be discerned. We confirm in detail an earlier report of the presence in the same deposits of tabulates, an extinct crown group anthozoan form. Other sections reveal structures that most closely resemble sections of basal modern corals. A large number of fossils similar to modern hydrozoan gastrulae were also observed. These again displayed great morphological consistency. Though only a single example is available, a microscopic animal remarkably similar to a modern adult hydrozoan is also presented. Taken together, the new observations reported in this paper indicate the existence of a diverse and already differentiated cnidarian fauna, long before the Cambrian evolutionary event. It follows that at least stem group bilaterians must also have been present at this time

The \u3cem\u3eSOX9\u3c/em\u3e upstream region prone to chromosomal aberrations causing campomelic dysplasia contains multiple cartilage enhancers

Two decades after the discovery that heterozygous mutations within and around SOX9 cause campomelic dysplasia, a generalized skeleton malformation syndrome, it is well established that SOX9 is a master transcription factor in chondrocytes. In contrast, the mechanisms whereby translocations in the –350/–50-kb region 5 of SOX9 cause severe disease and whereby SOX9 expression is specified in chondrocytes remain scarcely known. We here screen this upstream region and uncover multiple enhancers that activate Sox9-promoter transgenes in the SOX9 expression domain. Three of them are primarily active in chondrocytes. E250 (located at – 250 kb) confines its activity to condensed prechondrocytes, E195 mainly targets proliferating chondrocytes, and E84 is potent in all differentiated chondrocytes. E84 and E195 synergize with E70, previously shown to be active in most Sox9-expressing somatic tissues, including cartilage. While SOX9 protein powerfully activates E70, it does not control E250. It requires its SOX5/SOX6 chondrogenic partners to robustly activate E195 and additional factors to activate E84. Altogether, these results indicate that SOX9 expression in chondrocytes relies on widely spread transcriptional modules whose synergistic and overlapping activities are driven by SOX9, SOX5/SOX6 and other factors. They help elucidate mechanisms underlying campomelic dysplasia and will likely help uncover other disease mechanisms

Signatures of multi-TeV scale particles in supersymmetric theories

Supersymmetric particles at the multi-TeV scale will escape direct detection at planned future colliders. However, such particles induce non-decoupling corrections in processes involving the accessible superparticles through violations of the supersymmetric equivalence between gauge boson and gaugino couplings. In a previous study, we parametrized these violations in terms of super-oblique parameters and found significant deviations in well-motivated models. Here, we systematically classify the possible experimental probes of such deviations, and present detailed investigations of representative observables available at a future linear collider. In some scenarios, the $e^-e^-$ option and adjustable beam energy are exploited to achieve high precision. It is shown that precision measurements are possible for each of the three coupling relations, leading to significant bounds on the masses and properties of heavy superparticles and possible exotic sectors.Comment: 37 pages including 17 figures, REVTe

The nucleolar protein NIFK promotes cancer progression via CK1α/β-catenin in metastasis and Ki-67-dependent cell proliferation.

Nucleolar protein interacting with the FHA domain of pKi-67 (NIFK) is a Ki-67-interacting protein. However, its precise function in cancer remains largely uninvestigated. Here we show the clinical significance and metastatic mechanism of NIFK in lung cancer. NIFK expression is clinically associated with poor prognosis and metastasis. Furthermore, NIFK enhances Ki-67-dependent proliferation, and promotes migration, invasion in vitro and metastasis in vivo via downregulation of casein kinase 1α (CK1α), a suppressor of pro-metastatic TCF4/β-catenin signaling. Inversely, CK1α is upregulated upon NIFK knockdown. The silencing of CK1α expression in NIFK-silenced cells restores TCF4/β-catenin transcriptional activity, cell migration, and metastasis. Furthermore, RUNX1 is identified as a transcription factor of CSNK1A1 (CK1α) that is negatively regulated by NIFK. Our results demonstrate the prognostic value of NIFK, and suggest that NIFK is required for lung cancer progression via the RUNX1-dependent CK1α repression, which activates TCF4/β-catenin signaling in metastasis and the Ki-67-dependent regulation in cell proliferation

Super-oblique corrections and non-decoupling of supersymmetry breaking

If supersymmetric partners of the known particles have masses at the multi-TeV scale, they will not be directly discovered at planned future colliders and decouple from most observables. However, such superpartners also induce non-decoupling effects that break the supersymmetric equivalence of gauge boson couplings $g_i$ and gaugino couplings $h_i$ through supersymmetric analogues of the oblique corrections. Working within well-motivated theoretical frameworks, we find that multi-TeV scale supersymmetric particles produce deviations at the 1-10% level in the ratios $h_i/g_i$. Such effects allow one to bound the scale of kinematically inaccessible superpartners through precision measurements of processes involving the accessible superparticles. Alternatively, if all superpartners are found, significant deviations imply the existence of highly split exotic supermultiplets.Comment: 18 pages, REVTeX, no figur