An Effective pTp_T Cutoff for the Isolalated Lepton Background from Bottom Decay --

There is a strong correlation between the $p_T$ and isolation of the lepton coming from $B$ decay. Consequently the isolated lepton background from $B$ decay goes down rapidly with increasing lepton $p_T$; and there is a $p_T$ cutoff beyond which it effectively vanishes. For the isolation cut of $E^{AC}_T < 10$ GeV, appropriate for LHC, the lepton $p_T$ cutoff is 80 GeV. This can be exploited to effectively eliminate the $B$ background from the like sign dilepton channel apropriate for Majorana particle searches, as well as the unlike sign dilepton and the single lepton channels appropriate for the top quark search. We illustrate this with a detailed analysis of the $B$ background in these channels along with the signals at LHC energy using both parton level MC and ISAJET programs.Comment: TIFR/TH/93-23 (LATEX, 20 pages, 7 figures available on request

Opća teorija popravki višeg reda za solitonske valove u višekomponentnoj plazmi

A generalized theory on the combined effects of ion-temperature, negative ions and higher-order corrections on ion-acoustic solitary waves in a multicomponent plasma containing warm, relativistic positive ions and negative ions, two-temperature and non-isothermal electrons has been made using reductive perturbation method. The basic set of fluid equations for the warm ion-fluids have been reduced to the renormalized Korteweg-de-Vries equation for the first-order perturbed potential and then a renormalized linear inhomogeneous equation for the second-order perturbed potential. Steady-state solutions of the coupled equations have been derived and eventually the solution representing the potential associated with the ion-acoustic wave has been obtained. The soliton profiles have been displayed graphically under various conditions.Primjenom reduktivne metode smetnje, razvili smo poopćenu teoriju složenih učinaka temperature iona, negativnih iona i popravaka višeg reda na ionsko-zvučne solitarne valove u višekomponentnoj plazmi koja sadrži tople relativističke pozitivne i negativne ione, te dvotemperaturne i neizotermičke elektrone. Osnovni skup jednadžbi fluida za tople ionske fluide svodi se na renormaliziranu Korteweg–de-Vries jednadžbu za potencijal smetnje prvog reda i zatim na renormaliziranu linearnu nehomogenu jednadžbu za potencijal smetnje drugog reda. Izveli smo rješenja vezanih jednadžbi i konačno rješenje koje predstavlja potencijal povezan s ionsko-zvučnim valom. Grafički predstavljamo solitonske oblike u različitim uvjetima