Search for heavy long-lived particles that decay to photons at CDF II.
Phys Rev Lett 99:12 (2007) 121801
Abstract:
We present the first search for heavy, long-lived particles that decay to photons at a hadron collider. We use a sample of gamma + jet + missing transverse energy events in pp[over] collisions at square root[s] = 1.96 TeV taken with the CDF II detector. Candidate events are selected based on the arrival time of the photon at the detector. Using an integrated luminosity of 570 pb(-1) of collision data, we observe 2 events, consistent with the background estimate of 1.3+/-0.7 events. While our search strategy does not rely on model-specific dynamics, we set cross section limits in a supersymmetric model with [Formula: see text] and place the world-best 95% C.L. lower limit on the [Formula: see text] mass of 101 GeV/c(2) at [Formula: see text].Measurement of the atmospheric muon charge ratio at TeV energies with the MINOS detector
Physical Review D - Particles, Fields, Gravitation and Cosmology 76:5 (2007)
Abstract:
The 5.4 kton MINOS far detector has been taking charge-separated cosmic ray muon data since the beginning of August, 2003 at a depth of 207 m.w.e. in the Soudan Underground Laboratory, Minnesota, USA. The data with both forward and reversed magnetic field running configurations were combined to minimize systematic errors in the determination of the underground muon charge ratio. When averaged, two independent analyses find the charge ratio underground to be Nμ+/Nμ-=1.374±0.004(stat)-0.010+0.012(sys). Using the map of the Soudan rock overburden, the muon momenta as measured underground were projected to the corresponding values at the surface in the energy range 1-7 TeV. Within this range of energies at the surface, the MINOS data are consistent with the charge ratio being energy independent at the 2 standard deviation level. When the MINOS results are compared with measurements at lower energies, a clear rise in the charge ratio in the energy range 0.3-1.0 TeV is apparent. A qualitative model shows that the rise is consistent with an increasing contribution of kaon decays to the muon charge ratio. © 2007 The American Physical Society.Combined D0 measurements constraining the CP-violating phase and width difference in the Bs0 system
Physical Review D - Particles, Fields, Gravitation and Cosmology 76:5 (2007)
Abstract:
We combine the D0 measurement of the width difference between the light and heavy Bs0 mass eigenstates and of the CP-violating mixing phase determined from the time-dependent angular distributions in the Bs0→J/ψ decays along with the charge asymmetry in semileptonic decays also measured with the D0 detector. With the additional constraint from the world average of the flavor-specific Bs0 lifetime, we obtain ΔΓs≡(ΓL- ΓH)=0.13±0.09ps-1 and | s|=0.70-0.47+0.39 or ΔΓs=-0. 13±0.09ps-1 and | s|=2.44-0.39+0.47. The data sample corresponds to an integrated luminosity of 1.1fb-1 accumulated with the D0 detector at the Fermilab Tevatron Collider. © 2007 The American Physical Society.Search for heavy long-lived particles that decay to photons at CDF II
Physical Review Letters 99:12 (2007)
Abstract:
We present the first search for heavy, long-lived particles that decay to photons at a hadron collider. We use a sample of Î+jet+missing transverse energy events in pp collisions at s=1.96 TeV taken with the CDF II detector. Candidate events are selected based on the arrival time of the photon at the detector. Using an integrated luminosity of 570pb-1 of collision data, we observe 2 events, consistent with the background estimate of 1.3 0.7 events. While our search strategy does not rely on model-specific dynamics, we set cross section limits in a supersymmetric model with I E 10 GE and place the world-best 95% C.L. lower limit on the χ˜10 mass of 101 GeV/c2 at Ï.,χ˜10=5ns. © 2007 The American Physical Society.Search for third-generation scalar leptoquarks in pp at square root s=1.96 TeV.
Phys Rev Lett 99:6 (2007) 061801