3,498 research outputs found

    Searches for production of two Higgs bosons using the CMS detector

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    AbstractFour searches for the production of two Higgs bosons using the CMS detector are presented. The analyses are performed on pp collision data collected during the Run I of the LHC at s=7 – 8 TeV corresponding to an integrated luminosity of 5.1 – 17.9-19.7 fb−1. The analyses are covering the resonant production of Higgs boson pairs in the bbâ€ŸÎłÎł and bb‟bb‟ final states for masses between 260 and 1100 GeV, the resonant production of Higgs boson pairs in multilepton and diphoton final states for masses between 260 and 360 GeV, as well as additional Higgs boson-like states in the diphoton spectrum for masses between 110 and 150 GeV. The observations are compatible with expectations from standard model processes, and upper limits at 95% confidence-level are extracted on the production cross section of new particles

    Effective field theory analysis of double Higgs boson production via gluon fusion

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    We perform a detailed study of double Higgs production via gluon fusion in the effective field theory (EFT) framework where effects from new physics (NP) are parametrized by local operators. Our analysis provides a perspective broader than the one followed in most of the previous analyses, where this process was merely considered as a way to extract the Higgs trilinear coupling. We focus on the hh\u2192bb\uaf\u3b3\u3b3 channel and perform a thorough simulation of signal and background at the 14 TeV LHC and a future 100 TeV proton-proton collider. We make use of invariant mass distributions to enhance the sensitivity on the EFT coefficients and give a first assessment of the impact of jet substructure techniques on the results. The range of validity of the EFT description is estimated, as required to consistently exploit the high-energy range of distributions, pointing out the potential relevance of dimension-8 operators. Our analysis contains a few important improvements over previous studies and identifies some inaccuracies there appearing in connection with the estimate of signal and background rates. The estimated precision on the Higgs trilinear coupling that follows from our results is less optimistic than previously claimed in the literature. We find that a 3c30% accuracy can be reached on the trilinear coupling at a future 100 TeV collider with 3 ab-1. Only an O(1) determination instead seems possible at the LHC with the same amount of integrated luminosit

    Higgs boson production via vector-like top-partner decays: diphoton or multilepton plus multijets channels at the LHC

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    We first build a minimal model of vector-like quarks where the dominant Higgs boson production process at LHC -- the gluon fusion -- can be significantly suppressed, being motivated by the recent stringent constraints from the search for direct Higgs production over a wide Higgs mass range. Within this model, compatible with the present experimental constraints on direct Higgs searches, we demonstrate that the Higgs (hh) production via a heavy vector-like top-partner (t2t_2) decay, pp→t2tˉ2pp \to t_2 \bar t_2, t2→tht_2\to t h, allows to discover a Higgs boson at the LHC and measure its mass, through the decay channels h→γγh\to \gamma\gamma or h→ZZh\to ZZ. We also comment on the recent hint in LHC data from a possible ∌125\sim 125 GeV Higgs scalar, in the presence of heavy vector-like top quarks.Comment: 14 pages, 8 figure

    Huge Electro-/photo-/acidoinduced Second-order Nonlinear Contrasts from Multiaddressable Indolinooxazolodine

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    In this work, linear and nonlinear optical properties of electro-/acido-/photoswitchable indolino[2,1-b]oxazolidine derivatives were investigated. The linear optical properties of the closed and open forms have been characterized by UV–visible and IR spectroscopies associated with DFT calculations. Nonlinear optical properties of the compounds have been obtained by ex situ and in situ hyper-Rayleigh experiments in solution. We show that protonated, oxidized, and irradiated open forms exhibit the same visible absorption and NLO features. In particular, the closed and open forms exhibit a huge contrast of the first hyperpolarizability with an enhancement factor of 40–45. Additionally, we have designed an original electrochemical cell that allows to monitor in situ the hyper-Rayleigh response upon electrical stimulus. We report notably a partial but good and reversible NLO contrast in situ during oxidation/reduction cycles. Thereby, indolinooxazolidine moieties are versatile trimodal switchable units which are very promising for applications in devices

    A Mission to Explore the Pioneer Anomaly

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    The Pioneer 10 and 11 spacecraft yielded the most precise navigation in deep space to date. These spacecraft had exceptional acceleration sensitivity. However, analysis of their radio-metric tracking data has consistently indicated that at heliocentric distances of ∌20−70\sim 20-70 astronomical units, the orbit determinations indicated the presence of a small, anomalous, Doppler frequency drift. The drift is a blue-shift, uniformly changing with a rate of ∌(5.99±0.01)×10−9\sim(5.99 \pm 0.01)\times 10^{-9} Hz/s, which can be interpreted as a constant sunward acceleration of each particular spacecraft of aP=(8.74±1.33)×10−10m/s2a_P = (8.74 \pm 1.33)\times 10^{-10} {\rm m/s^2}. This signal has become known as the Pioneer anomaly. The inability to explain the anomalous behavior of the Pioneers with conventional physics has contributed to growing discussion about its origin. There is now an increasing number of proposals that attempt to explain the anomaly outside conventional physics. This progress emphasizes the need for a new experiment to explore the detected signal. Furthermore, the recent extensive efforts led to the conclusion that only a dedicated experiment could ultimately determine the nature of the found signal. We discuss the Pioneer anomaly and present the next steps towards an understanding of its origin. We specifically focus on the development of a mission to explore the Pioneer Anomaly in a dedicated experiment conducted in deep space.Comment: 8 pages, 9 figures; invited talk given at the 2005 ESLAB Symposium "Trends in Space Science and Cosmic Vision 2020", 19-21 April 2005, ESTEC, Noordwijk, The Netherland

    Fundamental Physics with the Laser Astrometric Test Of Relativity

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    The Laser Astrometric Test Of Relativity (LATOR) is a joint European-U.S. Michelson-Morley-type experiment designed to test the pure tensor metric nature of gravitation - a fundamental postulate of Einstein's theory of general relativity. By using a combination of independent time-series of highly accurate gravitational deflection of light in the immediate proximity to the Sun, along with measurements of the Shapiro time delay on interplanetary scales (to a precision respectively better than 0.1 picoradians and 1 cm), LATOR will significantly improve our knowledge of relativistic gravity. The primary mission objective is to i) measure the key post-Newtonian Eddington parameter \gamma with accuracy of a part in 10^9. (1-\gamma) is a direct measure for presence of a new interaction in gravitational theory, and, in its search, LATOR goes a factor 30,000 beyond the present best result, Cassini's 2003 test. The mission will also provide: ii) first measurement of gravity's non-linear effects on light to ~0.01% accuracy; including both the Eddington \beta parameter and also the spatial metric's 2nd order potential contribution (never measured before); iii) direct measurement of the solar quadrupole moment J2 (currently unavailable) to accuracy of a part in 200 of its expected size; iv) direct measurement of the "frame-dragging" effect on light by the Sun's gravitomagnetic field, to 1% accuracy. LATOR's primary measurement pushes to unprecedented accuracy the search for cosmologically relevant scalar-tensor theories of gravity by looking for a remnant scalar field in today's solar system. We discuss the mission design of this proposed experiment.Comment: 8 pages, 9 figures; invited talk given at the 2005 ESLAB Symposium "Trends in Space Science and Cosmic Vision 2020," 19-21 April 2005, ESTEC, Noodrwijk, The Netherland