Search for anomalous t t-bar production in the highly-boosted all-hadronic final state

A search is presented for a massive particle, generically referred to as a Z', decaying into a t t-bar pair. The search focuses on Z' resonances that are sufficiently massive to produce highly Lorentz-boosted top quarks, which yield collimated decay products that are partially or fully merged into single jets. The analysis uses new methods to analyze jet substructure, providing suppression of the non-top multijet backgrounds. The analysis is based on a data sample of proton-proton collisions at a center-of-mass energy of 7 TeV, corresponding to an integrated luminosity of 5 inverse femtobarns. Upper limits in the range of 1 pb are set on the product of the production cross section and branching fraction for a topcolor Z' modeled for several widths, as well as for a Randall--Sundrum Kaluza--Klein gluon. In addition, the results constrain any enhancement in t t-bar production beyond expectations of the standard model for t t-bar invariant masses larger than 1 TeV.Comment: Submitted to the Journal of High Energy Physics; this version includes a minor typo correction that will be submitted as an erratu

Studies of jet mass in dijet and W/Z plus jet events

This is the pre-print version of the final published paper that is available from the link below.Invariant mass spectra for jets reconstructed using the anti-kT and Cambridge-Aachen algorithms are studied for different jet “grooming” techniques in data corresponding to an integrated luminosity of 5 fb-1, recorded with the CMS detector in proton-proton collisions at the LHC at a center-of-mass energy of 7TeV. Leading-order QCD predictions for inclusive dijet and W/Z+jet production combined with parton-shower Monte Carlo models are found to agree overall with the data, and the agreement improves with the implementation of jet grooming methods used to distinguish merged jets of large transverse momentum from softer QCD gluon radiation

Extensive Skin Calcifications in an Infant with Chronic Renal Failure: Metastatic Calcinosis Cutis

Calcinosis cutis, one of the rare manifestations of systemic calcinosis, is characterized by the deposition of calcium and phosphate salts in the skin. Metastatic calcinosis, usually a late complication of chronic renal failure, arises from increased calcium or phosphate levels in the serum or both. Both sexes and all ages may be affected; however, cutaneous involvement is uncommon, particularly in children. We present the youngest patient, to our knowledge, with end-stage renal disease and cutaneous metastatic calcification resulting from secondary hyperparathyroidism. A 2-month-old infant presented to the pediatric service with anuria and uremia. A renal biopsy specimen showed chronic tubulo-interstitial nephritis. Indurated, firm, tender reddish papules were localized to both lower limbs, and extensive irregular nodules and plaques with ulceration and white stony contents were localized to the right upper limb. Topical antibiotic ointment was applied to the skin lesions to prevent secondary infection. However, acute peritonitis developed during peritoneal dialysis, and death occurred as a result of sepsis