Production properties of low-mass systems in pp collisions at 102 GeV/c

We examine in detail the properties of low-mass systems produced in the inclusive reaction p + p --> p + anything at 102 GeV/c. We find that the internal characteristics of these low-mass nucleon-multipion systems (the "anything"), at fixed values of mass (M), are similar to those found for produced hadrons in high-energy collisions at fixed incident hadron energies . The resemblance between the properties of the M2 system and the characteristics of [pi]p collisions at s = M2 is particularly striking.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22250/1/0000686.pd

Antiproton proton annihilations at 1.6-2.2 GeV/c into final states with a K1o meson

Antiproton proton annihilations into final states containing at least one K1o meson have been studied in a 150 000 picture bubble chamber experiment. The experiment covered six incident antiproton momenta in the range 1.6-2.2 GeV/c. Cross sections at each incident momentum are determined for the more abundantly produced final states, and momentum averaged cross sections are determined for some rarer final states, including . Copious resonance production, including double resonance production, is observed, and percentage contributions of different resonance channels are evaluated. Cross sections and resonance fractions are compared with results of other experiments at antiproton momenta in the range 0.7-3.7 GeV/c.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34085/1/0000364.pd

Laboratory angular distributions for the production of charged secondaries in inelastic proton-proton collisions at 102 GeV/c

Lab angular distributions for the production of charged secondary particles in inelastic proton-proton collisions are presented. Data are separately displayed for protons and for positive and negative mesons (pions and kaons combined).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22255/1/0000691.pd

Branching ratio change in K- absorption at rest and the nature of the Lambda(1405)

We investigate in-medium corrections to the branching ratio in K- absorption at rest and their effect on the (positively and negatively) charged pion spectrum. The in-medium corrections are due to Pauli blocking, which arises if the Lambda(1405) is assumed to be a $\bar{K}$-nucleon bound state and leads to a density and momentum dependent mass shift of the Lambda(1405). Requiring that the optical potential as well as the branching ratio are derived from the same elementary T-matrix, we find that the in-medium corrected, density dependent T-matrix gives a better description of the K- absorption reaction than the free, density-independent one. This result suggests that the dominant component of the Lambda(1405) wave function is the $\bar{K}N$ bound state.Comment: 8 Pages, Revtex with epsf, and embedded 8 ps figure

Search for Ultra High Energy (UHE) γ-ray counterparts of BATSE 3B catalog events

We search for a Ultra High Energy (E>1014 eV)(E>1014eV) counterpart source to cosmic γ-ray bursts detected with the BATSE detectors. Using the 3B catalog positions, we examine 115 candidate bursts with the CASA-MIA detector for UHE γ-ray emission at or near the time of the observed γ-ray burst. No statistically significant excess of γ-rays is found from any of the candidate event regions. Based upon these results, we calculate the flux limits for UHE emission from these candidate event regions. Typical 95% confidence level flux limits are about 6×10−12 γ  cm−2 sec−16×10−12γcm−2sec−1 at a γ-ray detection threshold of 160 TeV. © 1996 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87368/2/598_1.pd

Search for physics beyond the standard model in events with τ leptons, jets, and large transverse momentum imbalance in pp collisions at [Formula: see text].

A search for physics beyond the standard model is performed with events having one or more hadronically decaying τ leptons, highly energetic jets, and large transverse momentum imbalance. The data sample corresponds to an integrated luminosity of 4.98 fb-1 of proton-proton collisions at [Formula: see text] collected with the CMS detector at the LHC in 2011. The number of observed events is consistent with predictions for standard model processes. Lower limits on the mass of the gluino in supersymmetric models are determined

Probing color coherence effects in pp collisions at [Formula: see text].

A study of color coherence effects in pp collisions at a center-of-mass energy of 7[Formula: see text] is presented. The data used in the analysis were collected in 2010 with the CMS detector at the LHC and correspond to an integrated luminosity of 36 pb[Formula: see text]. Events are selected that contain at least three jets and where the two jets with the largest transverse momentum exhibit a back-to-back topology. The measured angular correlation between the second- and third-leading jet is shown to be sensitive to color coherence effects, and is compared to the predictions of Monte Carlo models with various implementations of color coherence. None of the models describe the data satisfactorily

Measurement of jet multiplicity distributions in [Formula: see text] production in pp collisions at [Formula: see text].

The normalised differential top quark-antiquark production cross section is measured as a function of the jet multiplicity in proton-proton collisions at a centre-of-mass energy of 7[Formula: see text] at the LHC with the CMS detector. The measurement is performed in both the dilepton and lepton+jets decay channels using data corresponding to an integrated luminosity of 5.0[Formula: see text]. Using a procedure to associate jets to decay products of the top quarks, the differential cross section of the [Formula: see text] production is determined as a function of the additional jet multiplicity in the lepton+jets channel. Furthermore, the fraction of events with no additional jets is measured in the dilepton channel, as a function of the threshold on the jet transverse momentum. The measurements are compared with predictions from perturbative quantum chromodynamics and no significant deviations are observed