Scientific and Technical Aerospace Reports

Scientific and Technical Aerospace Reports
Author:
Publisher:
Total Pages: 804
Release: 1994
Genre: Aeronautics
ISBN:

Download Scientific and Technical Aerospace Reports Book in PDF, Epub and Kindle

Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.

Search for Pair-produced Vector-like B Quarks in Proton-proton Collisions at $\sqrt{s}$

Search for Pair-produced Vector-like B Quarks in Proton-proton Collisions at $\sqrt{s}$
Author:
Publisher:
Total Pages: 46
Release: 2015
Genre:
ISBN:

Download Search for Pair-produced Vector-like B Quarks in Proton-proton Collisions at $\sqrt{s}$ Book in PDF, Epub and Kindle

A search for the production of a heavy B quark, having electric charge -1/3 and vector couplings to W, Z, and H bosons, is carried out using proton-proton collision data recorded at the CERN LHC by the CMS experiment, corresponding to an integrated luminosity of 19.7 fb-1 . The B quark is assumed to be pair-produced and to decay in one of three ways: to tW, bZ, or bH. The search is carried out in final states with one, two, and more than two charged leptons, as well as in fully hadronic final states. Each of the channels in the exclusive final-state topologies is designed to be sensitive to specific combinations of the B quark-antiquark pair decays. The observed event yields are found to be consistent with the standard model expectations in all the fi- nal states studied. Our statistical combination of these results was performed and upper limits were set on the cross section of the strongly produced B quark-antiquark pairs as a function of the B quark mass. Additionally, lower limits on the B quark mass between 740 and 900 GeV are set at a 95% confidence level, depending on the values of the branching fractions of the B quark to tW, bZ, and bH. Overall, these limits are the most stringent to date.

Search for the Production of an Excited Bottom Quark Decaying to TW in Proton-proton Collisions at $\sqrt{s}

Search for the Production of an Excited Bottom Quark Decaying to TW in Proton-proton Collisions at $\sqrt{s}
Author:
Publisher:
Total Pages: 42
Release: 2015
Genre:
ISBN:

Download Search for the Production of an Excited Bottom Quark Decaying to TW in Proton-proton Collisions at $\sqrt{s} Book in PDF, Epub and Kindle

Our search is presented for a singly produced excited bottom quark (b*) decaying to a top quark and a W boson in the all-hadronic, lepton+jets, and dilepton final states in proton-proton collisions at √s = 8 TeV recorded by the CMS experiment at the CERN LHC. Data corresponding to an integrated luminosity of 19.7 fb-1 are used. No significant excess of events is observed with respect to standard model expectations. We set limits at 95% confidence on the product of the b* quark production cross section and its branching fraction to tW. Furthermore, the cross section limits are interpreted for scenarios including left-handed, right-handed, and vector-like couplings of the b* quark and are presented in the two-dimensional coupling plane based on the production and decay coupling constants. The masses of the left-handed, right-handed, and vectorlike b* quark states are excluded at 95% confidence below 1390, 1430, and 1530 GeV, respectively, for benchmark couplings. This analysis gives the most stringent limits on the mass of the b* quark to date.

Search for Single Production of Vector-like Quarks Decaying Into a B Quark and a W Boson in Proton-proton Collisions at $\sqrt{s}

Search for Single Production of Vector-like Quarks Decaying Into a B Quark and a W Boson in Proton-proton Collisions at $\sqrt{s}
Author:
Publisher:
Total Pages:
Release: 2017
Genre:
ISBN:

Download Search for Single Production of Vector-like Quarks Decaying Into a B Quark and a W Boson in Proton-proton Collisions at $\sqrt{s} Book in PDF, Epub and Kindle

A search is presented for a heavy vector-like quark, decaying into a b quark and a W boson, which is produced singly in association with a light flavor quark and a b quark. The analysis is performed using a data sample of proton-proton collisions at a center-of-mass energy of $\sqrt{s} = $ 13 TeV collected at the LHC in 2015. The data set used in the analysis corresponds to an integrated luminosity of 2.3 inverse-femtobarns. The search is carried out using events containing one electron or muon, at least one b-tagged jet with large transverse momentum, at least one jet in the forward region of the detector, and missing transverse momentum. No excess over the standard model prediction is observed. Upper limits are placed on the production cross section of heavy exotic quarks: a T quark with a charge of 2/3, and a Y quark with a charge of -4/3. For Y quarks with coupling of 0.5 and B(Y to bW) = 100%, the observed (expected) lower mass limits are 1.40 (1.0) TeV. This is the most stringent limit to date on the single production of the Y vector-like quark.

A Search for Excited Leptons in Pp Collisions at Sqrt(s)

A Search for Excited Leptons in Pp Collisions at Sqrt(s)
Author:
Publisher:
Total Pages: 29
Release: 2011
Genre:
ISBN:

Download A Search for Excited Leptons in Pp Collisions at Sqrt(s) Book in PDF, Epub and Kindle

A search for excited leptons is carried out with the CMS detector at the LHC, using 36 inverse picobarns of pp collision data recorded at sqrt(s) = 7 TeV. The search is performed for associated production of a lepton and an oppositely charged excited lepton pp to l l*, followed by the decay l* to l gamma, resulting in the l l gamma final state, where l = electron or muon. No excess of events above the standard model expectation is observed. Interpreting the findings in the context of l* production through four-fermion contact interactions and subsequent decay via electroweak processes, first upper limits are reported for l* production at this collision energy. The exclusion region in the compositeness scale Lambda and excited lepton mass M(l*) parameter space is extended beyond previously established limits. For Lambda = M(l*), excited lepton masses are excluded below 1070 GeV/c2̂ for e* and 1090 GeV/c2̂ for mu* at the 95% confidence level.