Search for heavy long-lived particles that decay to photons at CDF II

Enhancing Long-Lived Particles Searches at the LHC with Precision Timing Information

We explore the physics potential of using precision timing information at the LHC in searches for long-lived particles (LLPs). In comparison with the light standard model particles, the decay products of massive LLPs arrive at detectors with time delays around the nanosecond scale. We propose new strategies to take advantage of this time delay feature by using initial state radiation to time stamp the collision event and require at least one LLP to decay within the detector. This search strategy is effective for a broad range of models. In addition to outlining this general approach, we demonstrate its effectiveness with the projected reach for two benchmark scenarios: a Higgs boson decaying into a pair of LLPs, and pair production of long-lived neutralinos in the gauge mediated supersymmetry breaking models. Our strategy increases the sensitivity to the lifetime of the LLP by two orders of magnitude or more and particularly exhibits a better behavior with a linear dependence on the lifetime in the large lifetime region compared to traditional LLP searches. The timing information significantly reduces the standard model background and provides a powerful new dimension for LLP searches.

Search for supersymmetry with gauge-mediated breaking in diphoton events with missing transverse energy at CDF II

We present the results of a search for supersymmetry with gauge-mediated breaking and chi(1)(0) --> gammaG in the gammagamma + missing transverse energy final state. In 2.6+/-0.2 fb(-1) of pp collisions at square root(s) = 1.96 TeV recorded by the CDF II detector we observe no candidate events, consistent with a standard model background expectation of 1.4+/-0.4 events. We set limits on the cross section at the 95% C.L. and place the world's best limit of 149 GeV/c2 on the chi(1)(0) mass at tau(chi(1)(0)) << 1 ns. We also exclude regions in the chi(1)(0) mass-lifetime plane for tau(chi(1)(0)) approximately < 2 ns.

Nuclear EGFR as novel therapeutic target: insights into nuclear translocation and function

Emerging evidence suggests the existence of a new mode of epidermal growth factor receptor (EGFR) signaling in which activated EGFR undergoes nuclear translocation following treatment with ionizing radiation. The authors provide evidence that the nuclear EGFR transport is a stress-specific cellular reaction, which is linked to src-dependent EGFR internalization into caveolae. These flask-shaped pits can fuse with endoplasmic reticulum and the EGFR is sorted into a perinuclear localization. This compartment may serve as a reservoir for nuclear EGFR transport which is regulated by PKCepsilon (protein kinase Cepsilon). Nuclear EGFR is able to induce transcription of genes essential for cell proliferation and cell-cycle regulation. Moreover, nuclear EGFR has physical contact with compounds of the DNA repair machinery and is involved in removal of DNA damage. Anti-EGFR strategies target radiation-associated EGFR nuclear translocation in different manners. EGFR-inhibitory antibodies, i.e., cetuximab (Erbitux((R))), can block nuclear translocation by EGFR immobilization within the cytosol in responder cell lines, whereas tyrosine kinase inhibitors rather target nuclear kinase activity of EGFR linked with cytosolic or nuclear functions. However, both strategies can inhibit DNA repair following irradiation.