document: as in our previous analysis of run 1a data  @xcite , we conduct a general search for new particles with a narrow natural width that decay to dijets . in addition 
   , we search for the following particles summarized in fig . 
   [ fig_particles ] : axigluons  @xcite from chiral qcd ( @xmath7 ) , excited states  @xcite of composite quarks ( @xmath8 ) , color octet technirhos  @xcite ( @xmath9 ) , new gauge bosons ( @xmath10,@xmath11 ) , and scalar @xmath12 diquarks  @xcite ( @xmath13 and @xmath14 ) . 
   using four triggers from run 1a and 1b , we combine dijet mass spectra above a mass of 150 gev / c@xmath1 , 241 gev / c@xmath1 , 292 gev / c@xmath1 , and 388 gev / c@xmath1 with integrated luminosities of    = 7.5 in    = 3.3 in = 3.3 in    .089 pb@xmath0 , 1.92 pb@xmath0 , 9.52 pb@xmath0 , and 69.8 pb@xmath0 respectively . 
   jets are defined with a fixed cone clustering algorithm ( r=0.7 ) and then corrected for detector response , energy lost outside the cone , and underlying event . 
   we take the two highest @xmath15 jets and require that they have pseudorapidity @xmath16 and a cms scattering angle @xmath17| < 2/3 $ ] . 
   the @xmath18 cut provides uniform acceptance as a function of mass and reduces the qcd background which peaks at @xmath19 . in fig . 
   [ fig_dijet ] the dijet mass distribution is presented as a differential cross section in bins of the mass resolution ( @xmath20% ) . at high mass 
   the data is systematically higher than a prediction from pythia plus a cdf detector simulation , similar to the inclusive jet @xmath21 spectrum  @xcite . to search for new particles we determine the qcd background by fitting the data to a smooth function of three parameters  @xcite ; fig . 
   [ fig_dijet ] shows the fractional difference between the data and the fit ( @xmath22 ) . 
   we note upward fluctuations near 200 gev / c@xmath1 ( @xmath23 ) , 550 gev / c@xmath1 ( @xmath24 ) and 850 gev / c@xmath1 ( @xmath25 ) .    for narrow resonances 
   it is sufficient to determine the mass resolution for only one type of new particle because the detector resolution dominates the width . in fig . 
   [ fig_resonance ] we show the mass resolution for excited quarks ( q * ) from pythia plus a cdf detector simulation ; the long tail at low mass comes from gluon radiation . for each value of new particle mass in 50 gev / c@xmath1 steps , 
   we perform a binned maximum likelihood fit of the data to the background parameterization and the mass resonance shape . in fig . 
   [ fig_resonance ] we display the best fit and 95% confidence level upper limit for a 550 gev / c@xmath1 resonance . for the mass region @xmath26 
   gev / c@xmath1 , there are 2947 events in the data , @xmath27 events ( @xmath28 ) in the background for the fit without a resonance , @xmath29 events ( @xmath30 ) in the background for the fit that includes the resonance , and the value of the resonance cross section from the fit is @xmath31 pb ( statistical ) .    in fig . 
   [ fig_cos ] we study the angular distribution of the fluctuation in the mass region @xmath26 gev / c@xmath1 . 
   the angular distribution is compatible with both qcd alone , and with    = 3.3 in = 3.3 in    qcd + 5% excited quark ( best fit ) . 
   this amount of excited quark is coincidentally the same as found in the mass fit . 
   although the fluctuation is interesting , we conclude it is not yet    = 3.3 in = 3.3 in    statistically significant , and proceed to set limits on new particle production . 
   = 3.3 in = 3.3 in    from the likelihood distribution including experimental systematic uncertainties  @xcite we obtain the 95% cl upper limit on the cross section for new particles shown in fig . 
   [ fig_dijet_limit ] . 
   we compare this to the cross section for axigluons ( excluding @xmath32 gev / c@xmath1 ) , excited quarks ( excluding @xmath33 gev / c@xmath1 ) , technirhos ( excluding @xmath34 gev / c@xmath1 ) , w@xmath35 ( excluding @xmath36 gev / c@xmath1 ) , z@xmath35 ( excluding @xmath37 gev / c@xmath1 ) , and e6 diquarks ( excluding @xmath38 gev / c@xmath1 ) . 
   the calculations are lowest order  @xcite using cteq2l parton distributions  @xcite and one - loop @xmath39 and require @xmath16 and @xmath40 . 
   the large mass of the top quark suggests that the third generation may be special . 
   topcolor  @xcite assumes that the top mass is large mainly because of a dynamical @xmath5 condensate generated by a new strong dynamics coupling to the third generation . here 
   the @xmath41 of qcd is a low energy symmetry arising from the breaking of an @xmath42 coupling to the third generation and an @xmath43 coupling to the first two generations only . 
   there are then massive color octet bosons , topgluons @xmath44 , which couple largely to @xmath4 and @xmath5 . 
   the topgluon is strongly produced and decays mainly to the third generation ( @xmath45 ) with a relatively large natural width ( @xmath46 ) . 
   here we search for the topgluon in the @xmath4 channel . 
   an additional @xmath47 symmetry is introduced  @xcite to keep the @xmath48 quark light while the top quark is heavy ; this leads to a topcolor @xmath6 , which again couples largely to @xmath4 and @xmath5 . 
   the topcolor @xmath6 is electroweakly produced and decays mainly to the third generation ( @xmath49 ) with a narrow natural width ( @xmath50 ) . 
   here we search for the topcolor @xmath6 in both the the @xmath4 and @xmath5 channel ; the @xmath5 channel is the most sensitive because the coupling to @xmath5 is larger . 
   we start with the dijet search in 19 pb@xmath0 of run 1a data  @xcite and additionally require at least one of the two leading jets be tagged as a bottom quark . 
   the b - tag requires a displaced vertex in the the secondary vertex detector  @xcite . 
   the @xmath4 event efficiency is @xmath51% independent of dijet mass . from fits to the @xmath52 distribution 
   , we estimate that the sample is roughly 50% bottom , 30% charm , and 20% mistags of plain jets . 
   pythia predicts that 1/5 of these bottom quarks are direct @xmath4 , and the rest are from gluon splitting and flavor excitation . 
   consequentially , only about @xmath53% @xmath54 10% of our sample is direct @xmath4 . 
   we expect both the purity and efficiency to increase when we use the run 1b dataset and a new tagging algorithm  @xcite 
   . with higher tagging efficiency we should be able to make better use of double b - tagged events like the one in fig . 
   [ fig_btag_event ] . 
   = 2.6 in = 2.6 in    in fig . 
   [ fig_btag ] we show the b - tagged dijet mass distribution corrected for the @xmath4 efficiency . 
   also shown is the untagged dijet mass distribution from run 1a , and both are well fit with our standard parameterization  @xcite . 
   the b - tagged dijet data has an upward fluctuation near 600 gev / c@xmath1 . 
   we model the shape of a narrow resonance using pythia z@xmath3 production and a cdf detector simulation . in fig . 
   [ fig_btag ] we fit the b - tagged data to a 600 gev / c@xmath1 narrow resonance , and find a cross section of @xmath55 pb ( statistical ) . 
   note that this is comparable to the dijet fluctuation in both mass and rate . however , there are only 8 events in the last two data bins of fig . 
   [ fig_btag ] , and the fluctuation is only a @xmath56 effect , so we proceed to set limits on new particle production . 
   we perform two kinds of fits for the limits . 
   first , narrow resonances are modelled as described above , and the mass resolution in the cdf detector is shown in fig . 
   [ fig_b_bbar_res ] . 
   second , wide resonances characteristic of topgluons  @xcite , including interference with normal gluons , was incorporated into pythia and a cdf detector simulation . the mass resolution in fig . 
   [ fig_b_bbar_res ] displays destructive interference to the left of the resonance ; models with destructive interference on the right side of the resonance will be considered in the future . 
   = 3.2 in = 3.2 in    limits on new particle production are shown in fig . 
   [ fig_btag_limit ] . 
   the theoretical cross sections are lowest order and use cteq2l parton distributions . for narrow resonances the production cross sections are nt large enough for us to set mass limits at this time . for topgluons 
   the production cross sections  @xcite are larger , and we are able to exclude at 95% cl topgluons of width @xmath57 in the mass region @xmath58 gev / c@xmath1 , @xmath59 for @xmath60 gev / c@xmath1 , and @xmath61 for @xmath62 gev / c@xmath1 .    = 3.0 in = 3.0 in    = 7.7 in 
   to search for new particles decaying to @xmath5 we start with the data sample from the top mass measurement  @xcite . 
   there we used top decays to w + four jets with at least one b - tag , and found 19 events on a background of @xmath63 , resulting in a top mass of @xmath64(stat)@xmath65(sys ) gev / c@xmath1 . that analysis fit the entire event for the top hypothesis , discarding events with @xmath66 ( poor fit ) . 
   here we add the additional constraint that the top mass is 176 gev / c@xmath1 , which significantly enhances our resolution of the @xmath5 mass . 
   two of the 19 events fail the @xmath66 cut when the top mass constraint is added to the fit , leaving us with 17 events . 
   the @xmath5 mass distribution expected from a narrow resonance , normalized to the topcolor @xmath6 predicted rate  @xcite , is shown in fig . 
   [ fig_ttbar ] . 
   here we used pythia @xmath67 . 
   also in fig . 
   [ fig_ttbar ] is the monte carlo distribution of the background , on the left standard model top production from herwig , and on the right qcd w + jets background from vecbos with parton showers from herwig . 
   all monte carlos include a cdf detector simulation . on the left in fig . 
   [ fig_ttbar ] , the comparison of the topcolor z@xmath3 to sm @xmath5 simulations illustrates that in this data sample we are sensitive to topcolor @xmath6 up to a mass of roughly 600 gev / c@xmath1 . finally , on the right in fig . 
   [ fig_ttbar ] , we present the @xmath5 candidate mass distribution from cdf compared to the total standard model prediction . given the statistics the agreement is quite good overall . 
   the small shoulder of 6 events on a background of @xmath68 in the region @xmath69 gev / c@xmath1 is in an interesting mass region , given the dijet and @xmath4 search results , but is not statistically significant . 
   upper limits on the @xmath5 cross section as a function of @xmath5 mass , and on a topcolor @xmath6 , are currently in progress . 
   = 3.1 in = 3.1 in 
   we have searched for new particles decaying to dijets , @xmath4 , and @xmath5 . in the dijet channel we set the most significant direct mass exclusions to date on the hadronic decays of axigluons ( excluding @xmath70 gev / c@xmath1 ) , excited quarks ( excluding @xmath71 gev / c@xmath1 ) , technirhos ( excluding @xmath34 gev / c@xmath1 ) , w@xmath3 ( excluding @xmath36 gev / c@xmath1 ) , z@xmath35 ( excluding @xmath37 gev / c@xmath1 ) , and for the first time e6 diquarks ( excluding @xmath38 gev / c@xmath1 ) . in the @xmath4 channel 
   we set the first limits on topcolor , excluding a model of topgluons for width @xmath57 in the mass region @xmath58 gev / c@xmath1 , @xmath59 for @xmath60 gev / c@xmath1 , and @xmath61 for @xmath62 gev / c@xmath1 . 
   the search for topcolor in the @xmath5 channel has just begun and limits are in progress . 
   limits are only a consolation prize ; the main emphasis of our search is to explore the possibility of a signal . although we do not have significant evidence for new particle production , the @xmath72 gev / c@xmath1 region shows upward fluctuations in all three channels . 
   we can not ignore the exciting possibility that these apparently separate fluctuations may be the first signs of a new physics beyond the standard model . 
   the remaining integrated luminosity for run 1b , currently being accumulated and analyzed , has the potential to either kill the fluctuations or reveal what may be the most interesting new physics in a generation . 
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summary: we present three searches for new particles at cdf . first , using 70 pb@xmath0 of data we search the dijet mass spectrum for resonances . 
   there is an upward fluctuation near 550 gev / c@xmath1 ( 2.6@xmath2 ) with an angular distribution that is adequately described by either qcd alone or qcd plus 5% signal . 
   there is insufficient evidence to claim a signal , but we set the most stringent mass limits on the hadronic decays of axigluons , excited quarks , technirhos , w@xmath3 , z@xmath3 , and e6 diquarks . 
   second , using 19 pb@xmath0 of data we search the b - tagged dijet mass spectrum for @xmath4 resonances . 
   again , an upward fluctuation near 600 gev / c@xmath1 ( 2 @xmath2 ) is not significant enough to claim a signal , so we set the first mass limits on topcolor bosons . finally , using 67 pb@xmath0 of data we search the top quark sample for @xmath5 resonances like a topcolor @xmath6 . 
   other than an insignificant shoulder of 6 events on a background of 2.4 in the mass region 475 - 550 gev / c@xmath1 , there is no evidence for new particle production . 
   mass limits , currently in progress , should be sensitive to a topcolor z@xmath3 near 600 gev / c@xmath1 . in all three searches 
   there is insufficient evidence to claim new particle production , yet there is an exciting possibility that the upward fluctuations are the first signs of new physics beyond the standard model . 
   fermilab - conf-95/152-e + cdf / pub / exotic / public/3192 +   +    * search for new particles decaying to dijets , + @xmath4 , and @xmath5 at cdf + * _ fermilab ms 318 + batavia , il 60510 + _