Results 1 - 10 of 2584
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[en] We propose a new search strategy for directly-produced sbottoms at the LHC with a small mass splitting between the sbottom and its decayed stable neutralino. Our search strategy is based on boosting sbottoms through an energetic initial state radiation jet. In the final state, we require a large missing transverse energy and one or two b-jets besides the initial state radiation jet. We also define a few kinematic variables to further increase the discovery reach. For the case that the sbottom mainly decays into the bottom quark and the stable neutralino, we have found that even for a mass splitting as small as 10 GeV sbottoms with masses up to around 400 GeV can be excluded at the 95% confidence level with 20 inverse femtobarn data at the 8 TeV LHC.
[en] We report the differential cross-section for events with large total transverse energies, based on 112 pb-1 p anti p collisions at √s 1.8 TeV. The ratio of number of 3-jet to 2-jet events as a function of total transverse energy is also presented. Obtained results are compared with the QCD expectations. The properties of high mass six-jet events have been studied. Observed distributions are compared with the predictions of HER- WIG parton shower QCD, NJETS matrix element QCD, and a phase-space model in which events are uniformly distributed in the kinematic allowed region of phase space. A strong signal for Double Parton Scattering (DP) is observed in the process anti pp → γ + 3 jets + X, using data from the CDF experiment. The fundamental DP parameter σeff obtained, σeff = 14.5 + 1.71.7-2.3 mb, represents a significant improvement over previous measurements
[en] The signature characterized by 2 leptons and missing energy offers a very promising venue for the discovery and measurement of Supersymmetry signals at the LHC. The results on the search for this signature, performed with the data collected in 2010 by the ATLAS experiment, are presented.
[en] The threshold of the transverse mode coupling instability is calculated in framework of the square well model at arbitrary value of space charge tune shift. A new method of calculation is developed beyond the traditional expansion technique. The square, resistive, and exponential wakes are investigated. It is shown that the instability threshold goes up indefinitely when the tune shift increases. Finally, a comparison with conventional case of the parabolic potential well is performed.
[en] The transverse decoherence of the kicked beam due to amplitude dependent tune shift and the linear and the second order chromaticity are studied. For the kicked beam the closed analytical expression for the beam centroid evolution in subsequent turns is obtained. Analysis of the kicked beam centroid signal on the machine optical characteristics is given.
[en] The efficiency of electron cooling can be improved by reducing the temperature of the electrons. If the magnetic field at the location of the electron gun is stronger than in the region where the electrons interact with the ions, and the field gradient is adiabatic with respect to the cyclotron motion of the electrons, the resulting expansion of the electron beam reduces its transverse temperature by a factor equal to the ratio between the two fields. A ten times expanded electron beam was introduced in the CRYRING electron cooler in the summer of 1993, and similar arrangements have since then been made at the TSR ring in Heidelberg and at ASTRID in Aarhus. The reduction of the transverse electron temperature has increased cooling rates with large factors, and improves the energy resolution and increases count rates when the cooler is used as an electron target for ion-electron recombination experiments
[en] This paper seeks to demonstrate that many of the existing mass-measurement variables proposed for hadron colliders (mT, meff, mT2, missing p-vectorT, hT, √(s-circumflex)min, etc.) are far more closely related to each other than is widely appreciated, and indeed can all be viewed as a common mass-bound specialized for a variety of purposes. A consequence of this is that one may understand better the strengths and weaknesses of each variable, and the circumstances in which each can be used to best effect. In order to achieve this, we find it necessary first to revisit the seemingly empty and infertile wilderness populated by the subscript 'T' (as in 'peT') in order to remind ourselves what this process of transversification actually means. We note that, far from being simple, transversification can mean quite different things to different people. Those readers who manage to battle through the barrage of transverse notation distinguishing 'T' from 'v' or or from 'o', and 'early projection' from 'late projection', will find their efforts rewarded towards the end of the paper with (i) a better understanding of how collider mass variables fit together, (ii) an appreciation of how these variables could be generalized to search for things more complicated than supersymmetry, (iii) will depart with an aversion to thoughtless or naieve use of the so-called 'transverse methods' of any of the popular computer Lorentz-vector libraries, and (iv) will take care in their subsequent papers to be explicit about which of the 61 identified variants of the 'transverse mass' they are employing.
[en] The authors report on a search for large extra dimensions in a data sample of approximately 1 fb-1 of p(bar p) collisions at √s = 1.96 TeV. They investigate Kaluza-Klein graviton production with a photon and missing transverse energy in the final state. At the 95% C.L. they set limits on the fundamental mass scale MD from 884 GeV to 778 GeV for 2 to 8 extra dimensions
[en] We report the observation of laser oscillation in whispering-gallery mode (WGM) of a microcylinder with laser gain molecules present only in the evanescent field region of WGM. We show that the observe signal was originated from the evanescent-wave coupled gain of WGM. This novel concept of evanescent-wave WGM lasing offers potential applications in ultralow threshold photonic devices. (author)