The mass of the
boson, a mediator of the weak force between elementary particles, is tightly constrained by the symmetries of the standard model of particle physics. The Higgs boson was the last ...missing component of the model. After observation of the Higgs boson, a measurement of the
boson mass provides a stringent test of the model. We measure the
boson mass,
, using data corresponding to 8.8 inverse femtobarns of integrated luminosity collected in proton-antiproton collisions at a 1.96 tera-electron volt center-of-mass energy with the CDF II detector at the Fermilab Tevatron collider. A sample of approximately 4 million
boson candidates is used to obtain
, the precision of which exceeds that of all previous measurements combined (stat, statistical uncertainty; syst, systematic uncertainty; MeV, mega-electron volts;
, speed of light in a vacuum). This measurement is in significant tension with the standard model expectation.
Motivated by recent transport experiments and proposed atomic-scale semiconductor devices, we present measurements that extend the reach of scanned-probe methods to discern the properties of ...individual dopants tens of nanometers below the surface of a silicon sample. Using a capacitance-based approach, we have both spatially resolved individual subsurface boron acceptors and detected spectroscopically single holes entering and leaving these minute systems of atoms. A resonance identified as the B + state is shown to shift in energy from acceptor to acceptor. We examine this behavior with respect to nearest-neighbor distances. By directly measuring the quantum levels and testing the effect of dopant–dopant interactions, this method represents a valuable tool for the development of future atomic-scale semiconductor devices.
Abstract We report on a search for double beta decay of $$^{130}\hbox {Te}$$ 130Te to the first $$0^{+}$$ 0+ excited state of $$^{130}\hbox {Xe}$$ 130Xe using a $$9.8\,\hbox {kg}\cdot \hbox {yr}$$ ...9.8kg·yr exposure of $$^{130}\hbox {Te}$$ 130Te collected with the CUORE-0 experiment. In this work we exploit different topologies of coincident events to search for both the neutrinoless and two-neutrino double beta decay modes. We find no evidence for either mode and place lower bounds on the half-lives: $$T^{0\nu }_{0^+_1}>7.9\cdot 10^{23}\hbox {yr}$$ T01+0ν>7.9·1023yr and $$T^{2\nu }_{0^+_1}>2.4\cdot 10^{23}\hbox {yr}$$ T01+2ν>2.4·1023yr ($$90\%\,\hbox {CL}$$ 90%CL ). Combining our results with those obtained by the CUORICINO experiment, we achieve the most stringent constraints available for these processes: $$T^{0\nu }_{0^+_1}>1.4\cdot 10^{24}\hbox {yr}$$ T01+0ν>1.4·1024yr and $$T^{2\nu }_{0^+_1}>2.5\cdot 10^{23}\hbox {yr}$$ T01+2ν>2.5·1023yr ($$90\%\,\hbox {CL}$$ 90%CL ).
Intramolecular endo-cyclization reactions of N-acyliminium ions have seen wide application for the synthesis of heterocyclic compounds. The corresponding exocyclic variant, which would provide ...1-aminotetralin derivatives, for example, has little precedent. We have discovered that acyclic N-acylcarbamates can be readily reduced to the corresponding N-acylhemiaminal derivatives in high yield using DIBAL as the reducing agent. These intermediates are remarkably stable and, if desired, can be purified and stored. The acyclic N-acylhemiaminals undergo both intra- and intermolecular nucleophilic addition reactions mediated by strong Lewis acids, such as TiCl4. Diastereoselectivity, induced either by a substituent on the newly formed ring, or by utilizing a chiral ester on the carbamic acid, was disappointingly low. This methodology was successfully applied to the synthesis of the racemic form of the marketed antidepressant sertraline.
Abstract We report a study of the CUORE sensitivity to neutrinoless double beta ( $$0\nu \beta \beta $$ 0 ν β β ) decay. We used a Bayesian analysis based on a toy Monte Carlo (MC) approach to ...extract the exclusion sensitivity to the $$0\nu \beta \beta $$ 0 ν β β decay half-life ( $$T_{1/2}^{\,0\nu }$$ T 1 / 2 0 ν ) at $$90\%$$ 90 % credibility interval (CI) – i.e. the interval containing the true value of $$T_{1/2}^{\,0\nu }$$ T 1 / 2 0 ν with $$90\%$$ 90 % probability – and the $$3~\sigma $$ 3 σ discovery sensitivity. We consider various background levels and energy resolutions, and describe the influence of the data division in subsets with different background levels. If the background level and the energy resolution meet the expectation, CUORE will reach a $$90\%$$ 90 % CI exclusion sensitivity of $$2\cdot 10^{25}$$ 2 · 10 25 year with 3 months, and $$9\cdot 10^{25}$$ 9 · 10 25 year with 5 years of live time. Under the same conditions, the discovery sensitivity after 3 months and 5 years will be $$7\cdot 10^{24}$$ 7 · 10 24 year and $$4\cdot 10^{25}$$ 4 · 10 25 year, respectively.
The CDF and D0 experiments at the Fermilab Tevatron have measured the asymmetry between yields of forward- and backward-produced top and antitop quarks based on their rapidity difference and the ...asymmetry between their decay leptons. These measurements use the full data sets collected in proton-antiproton collisions at a center-of-mass energy of sqrts=1.96 TeV. We report the results of combinations of the inclusive asymmetries and their differential dependencies on relevant kinematic quantities. The combined inclusive asymmetry is A_{FB}^{ttover ¯}=0.128±0.025. The combined inclusive and differential asymmetries are consistent with recent standard model predictions.
We combine searches by the CDF and D0 Collaborations for the associated production of a Higgs boson with a W or Z boson and subsequent decay of the Higgs boson to a bottom-antibottom quark pair. The ...data, originating from Fermilab Tevatron pp collisions at √s = 1.96 TeV, correspond to integrated luminosities of up to 9.7 fb(-1). The searches are conducted for a Higgs boson with mass in the range 100-150 GeV/c(2). We observe an excess of events in the data compared with the background predictions, which is most significant in the mass range between 120 and 135 GeV/c(2). The largest local significance is 3.3 standard deviations, corresponding to a global significance of 3.1 standard deviations. We interpret this as evidence for the presence of a new particle consistent with the standard model Higgs boson, which is produced in association with a weak vector boson and decays to a bottom-antibottom quark pair.
We use a new method to estimate with 5% accuracy the contribution of pion and kaon in-flight-decays to the dimuon data set acquired with the CDF detector. Based on this improved estimate, we show ...that the total number and the properties of the collected dimuon events are not yet accounted for by ordinary sources of dimuons which also include the contributions, as measured in the data, of heavy flavor,
ϒ
, and Drell–Yan production in addition to muons mimicked by hadronic punchthrough. The number of unaccounted events corresponds to (12.8±3.2)% of the
production. We find that (23±6)% of the unaccounted events contain additional muon candidates. For comparison, this fraction is (6.9±0.4)% for events due to
production.
Higgs boson studies at the Tevatron Agnew, J. P.; Annovi, A.; Bandurin, D. V. ...
Physical review. D, Particles, fields, gravitation, and cosmology,
09/2013, Letnik:
88, Številka:
5
Journal Article
Recenzirano
Odprti dostop
We combine searches by the CDF and DO Collaborations for the standard model Higgs boson with mass in the range 90- 200 GeV /c super(2) produced in the gluon-gluon fusion, WH, ZH, ttH, and vector ...boson fusion processes, and decaying in the H arrow right bb, H arrow right W super(+)W super(-), H arrow right ZZ, H arrow right tau super(+)tau super(-), and H arrow right gamma gamma modes. The data correspond to integrated luminosities of up to 10 fb super(-1) and were collected at the Fermilab Tevatron in pp collisions at radicals = 1.96 TeV. The searches are also interpreted in the context of fermiophobic and fourth generation models. We observe a significant excess of events in the mass range between 115 and 140 GeV /c super(2). The local significance corresponds to 3.0 standard deviations at mH = 125 GeV /c super(2), consistent with the mass of the Higgs boson observed at the LHC, and we expect a local significance of 1.9 standard deviations. We separately combine searches for H arrow right bb, H arrow right W super(+)W super(-), H arrow right tau super(+)t super(-), and H arrow right gamma gamma . The observed signal strengths in all channels are consistent with the presence of a standard model Higgs boson with a mass of 125 GeV /c super(2).
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