Search results for "Branching"
showing 10 items of 918 documents
A note on coverings with special fibres and monodromy group $ S_{d}$
2012
We consider branched coverings of degree over with monodromy group , points of simple branching, special points and fixed branching data at the special points, where is a smooth connected complex projective curve of genus , and , are integers with . We prove that the corresponding Hurwitz spaces are irreducible if .
MINDO/3 Study of the Rearrangement of 1-Methylcyclohexyl Cation to 1,2-Dimethylcyclopentyl Cation
1986
The rearrangement of the 1-methylcyclohexyl cation to the 1,2-dimethylcyclopentyl cation has been studied by MINDO/3 calculations, as an application of the branching mechanism model for cycloalkanes. Possible intermediates and transition states have been characterized by diagonalization of their Hessian matrixes. Two nonequivalent pathways, α and β scissions, are relatively close in energy. The calculated transition states are almost equivalent in energy to those found for cyclohexyl cation. Hence, the energy barriers are higher for the rearrangement of the 1-methyl than for cyclohexyl cation, because the former is less stable than the latter.
A Fast Algorithm Finding the Shortest Reset Words
2013
In this paper we present a new fast algorithm for finding minimal reset words for finite synchronizing automata, which is a problem appearing in many practical applications. The problem is known to be computationally hard, so our algorithm is exponential in the worst case, but it is faster than the algorithms used so far and it performs well on average. The main idea is to use a bidirectional BFS and radix (Patricia) tries to store and compare subsets. Also a number of heuristics are applied. We give both theoretical and practical arguments showing that the effective branching factor is considerably reduced. As a practical test we perform an experimental study of the length of the shortest …
Long-Chain Branched Poly(Lactide)s Based on Polycondensation of AB2 -type Macromonomers
2012
A series of long-chain branched poly(d-/l-lactide)s is synthesized in a two-step protocol by (1) ring-opening polymerization of lactide and (2) subsequent condensation of the preformed AB2 macromonomers promoted by different coupling reagents. The linear AB2 macromonomers are prepared by Sn(Oct)2-catalyzed ROP of D- and L-lactide with 2,2-bis(hydroxymethyl)butyric acid (BHB) as an initiator. Optimization of the polymerization conditions allows for the preparation of well-defined macromonomers (Mw/Mn = 1.09–1.30) with adjustable molecular weights (760–7200 g mol−1). The two-step approach of the synthesis comprises as well the coupling of these AB2 macromonomers and hence allows precise contr…
Aliphatic Hyperbranched Copolyesters by Combination of ROP and AB2-Polycondensation
2005
Hyperbranched aliphatic copolyesters have been prepared by the copolymerization of e-caprolactone and 2,2-bis(hydroxymethyl)butyric acid (AB 2 -monomer), catalyzed by (i) HfCl 4 (THF) 2 and (ii) diphenylammonium trifluoromethanesulfonate (DPAT), respectively. In both cases, copolymerization by combined ROP/AB 2 -Polycondensation was achieved. The degree of branching (DB) and consequently the density of functional groups of the resulting copolyesters were controlled by the comonomer ratio in the feed. Molecular weights in the range M n =22 000-166 000 g mot -1 (GPC, PS standards) were obtained, with apparent polydispersity indices of 1.20 to 1.95. The DB was in the range 0.03-0.35. Remarkabl…
Search for a Charged Higgs Boson Produced in the Vector-Boson Fusion Mode with DecayH±→W±ZusingppCollisions ats=8 TeVwith the ATLAS Experiment
2015
A search for a charged Higgs boson, H-+/-, decaying to a W-+/- boson and a Z boson is presented. The search is based on 20.3 fb(-1) of proton-proton collision data at a center-of-mass energy of 8 TeV recorded with the ATLAS detector at the LHC. The H-+/- boson is assumed to be produced via vector-boson fusion and the decays W-+/- -> q (q') over bar and Z -> e(+)e(-)/mu(+)mu(-) are considered. The search is performed in a range of charged Higgs boson masses from 200 to 1000 GeV. No evidence for the production of an H+ boson is observed. Upper limits of 31-1020 fb at 95% C.L. are placed on the cross section for vector-boson fusion production of an H-+/- boson times its branching fraction to W…
Search for a multi-Higgs-boson cascade inW+W−bb¯events with the ATLAS detector inppcollisions ats=8 TeV
2014
A search is presented for new particles in an extension to the Standard Model that includes a heavy Higgs boson (H-0), an intermediate charged Higgs-boson pair (H-+/-), and a light Higgs boson (h(0)). The analysis searches for events involving the production of a single heavy neutral Higgs boson which decays to the charged Higgs boson and a W boson, where the charged Higgs boson subsequently decays into a W boson and the lightest neutral Higgs boson decaying to a bottom-antibottom-quark pair. Such a cascade results in a W-boson pair and a bottom-antibottom-quark pair in the final state. Events with exactly one lepton, missing transverse momentum, and at least four jets are selected from a d…
Lightest Higgs boson production at photon colliders in the two Higgs doublet model type III
2005
The branching ratios of the lightest $CP$-even Higgs boson ${h}^{0}$ are calculated in the framework of the general two higgs doublet model. Different scenarios are presented taking into account constraints on the flavor changing neutral currents factors obtained in previous works. Plausible scenarios where appear flavor changing processes at tree level like $b\overline{s}$ and $t\overline{c}$ are analyzed for relevant parameters. The loop-induced Higgs couplings to photon pairs can be tested with a photon collider. The number of events of ${h}^{0}$ as a resonance in photon colliders are calculated taking into account its corresponding background signal at TESLA, CLIC, and NLC.
Search for flavor changing neutral currents in decays of top quarks
2011
We present a search for flavor changing neutral currents in decays of top quarks. The analysis is based on a search for ttbar -> l'null + jets (l, l' = e, mu) final states using 4.1 fb^-1 of integrated luminosity of ppbar collisions at sqrt(s) = 1.96 TeV. We extract limits on the branching ratio B(t -> Zq) (q = u, c quarks), assuming anomalous tuZ or tcZ couplings. We do not observe any sign of such anomalous coupling and set a limit of B < 3.2% at 95% C.L.
Observation of ψ(3686)→η′e+e−
2018
Abstract Using a data sample of 448.1 × 10 6 ψ ( 3686 ) events collected with the BESIII detector at the BEPCII collider, we report the first observation of the electromagnetic Dalitz decay ψ ( 3686 ) → η ′ e + e − , with significances of 7.0σ and 6.3σ when reconstructing the η ′ meson via its decay modes η ′ → γ π + π − and η ′ → π + π − η ( η → γ γ ), respectively. The weighted average branching fraction is determined to be B ( ψ ( 3686 ) → η ′ e + e − ) = ( 1.90 ± 0.25 ± 0.11 ) × 10 − 6 , where the first uncertainty is statistical and the second systematic.