1,070 research outputs found

    Pileup subtraction using jet areas

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    One of the major challenges for the LHC will be to extract precise information from hadronic final states in the presence of the large number of additional soft pp collisions, pileup, that occur simultaneously with any hard interaction in high luminosity runs. We propose a novel technique, based on jet areas, that provides jet-by-jet corrections for pileup and underlying-event effects. It is data driven, does not depend on Monte Carlo modelling and can be used with any jet algorithm for which a jet area can be sensibly defined. We illustrate its effectiveness for some key processes and find that it can be applied also in the context of the Tevatron, low-luminosity LHC and LHC heavy-ion collisions.Comment: 12 pages, 7 figures. Revised version with many changes and additions, small and larger. No changes in conclusions. Version published in Physics Letters

    Probabilistic Particle Flow Algorithm for High Occupancy Environment

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    Algorithms based on the particle flow approach are becoming increasingly utilized in collider experiments due to their superior jet energy and missing energy resolution compared to the traditional calorimeter-based measurements. Such methods have been shown to work well in environments with low occupancy of particles per unit of calorimeter granularity. However, at higher instantaneous luminosity or in detectors with coarse calorimeter segmentation, the overlaps of calorimeter energy deposits from charged and neutral particles significantly complicate particle energy reconstruction, reducing the overall energy resolution of the method. We present a technique designed to resolve overlapping energy depositions of spatially close particles using a statistically consistent probabilistic procedure. The technique is nearly free of ad-hoc corrections, improves energy resolution, and provides new important handles that can improve the sensitivity of physics analyses: the uncertainty of the jet energy on an event-by-event basis and the estimate of the probability of a given particle hypothesis for a given detector response. When applied to the reconstruction of hadronic jets produced in the decays of tau leptons using the CDF-II detector at Fermilab, the method has demonstrated reliable and robust performance.Comment: Accepted by Nuclear Instruments and Methods

    Independent measurement of the top quark mass and the light- and bottom-jet energy scales at hadron colliders

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    A method for the simultaneous determination of the energy scales for b-quark jets and light jets, the jet energy resolution, and the top quark mass at hadron colliders is presented. The method exploits the unique kinematics of events with top-antitop pair production, where one of the top quarks involves a leptonic and one a hadronic W boson decay. The paper shows a feasibility study of how this simultaneous measurement can be performed at the upcoming LHC experiments ATLAS and CMS.Comment: 10 pages, 5 figure

    B physics at CDF - the Beauty of hadron collisions

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    The CDF experiment at the Tevatron p-pbar collider established that extensive and detailed exploration of the b-quark dynamics is possible in hadron collisions, with results competitive and supplementary to those from e+e- colliders. This provides an unique, rich, and highly rewarding program that is currently reaching full maturity. I report a few recent world-leading results on rare decays, CP-violation in Bs mixing, and b-> s penguin decays.Comment: 6 pages, 5 figures. Write-up of the proceedings of the "Third Workshop on Theory, Phenomenology and Experiments in Heavy Flavour Physics" (Capri2010

    B(Ds^+ -> l^+ nu) and the Decay Constant f_(D_s^+)

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    I report final CLEO-c results on the purely leptonic decays of the D_s^+ -> l^+ nu, for the cases when l^+ is a mu^+ or tau^+, when it decays into pi^+ anti-nu, using 314/pb of data at 4.170 GeV. I also include preliminary results from the tau^+ -> e^+ nu anti-nu channel using 195/pb. Combining both we measure f_{D_s}= 275 +/- 10 +/- 5 MeV, and f_{D_s^+}/{f_{D^+}=1.24 +/- 0.10 =/- 0.03 .Comment: Presented at "The 2007 Europhysics Conference on High Energy Physics," Manchester, England, 19-25 July 2007, to appear in the proceedings. Three pages, 1 figur

    In Pursuit of New Physics in the B System

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    The B-meson system offers interesting probes for the search of physics beyond the Standard Model. After addressing possible signals of new-physics contributions to the B -> phi K and B -> pi K decay amplitudes, we focus on the data for B^0_q-\bar B^0_q mixing (q = d, s), giving a critical discussion of their interpretation in terms of model-independent new-physics parameters. We address, in particular, the impact of the uncertainties of the relevant input parameters, discuss benchmarks for future precision measurements at the LHC, and explore the prospects for new CP-violating effects in the B_s-meson system, which could be detected at the LHC.Comment: 8 pages, 7 figures, invited talk at the 1st Workshop on Theory, Phenomenology and Experiments in Heavy Flavour Physics, Anacapri, Capri, Italy, 29-31 May 2006, to appear in the Proceeding

    Jets in Hadron-Hadron Collisions

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    In this article, we review some of the complexities of jet algorithms and of the resultant comparisons of data to theory. We review the extensive experience with jet measurements at the Tevatron, the extrapolation of this acquired wisdom to the LHC and the differences between the Tevatron and LHC environments. We also describe a framework (SpartyJet) for the convenient comparison of results using different jet algorithms.Comment: 68 pages, 54 figure

    Some Phenomenologies of Unparticle Physics

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    Fermionic unparticles are introduced and their basic properties are discussed. Some phenomenologies related are exploited, such as their effects on charged Higgs boson decays and anomalous magnetic moments of leptons. Also, it has been found that measurements of B0−Bˉ0B^0-\bar B^0 mixing could yield interesting constraints on couplings between unparticle operators and standard model fields.Comment: Version to appear in Phys. Letts. B. 9 pages, 3 figure

    Pilipinx Radical Imagination: Healing and Visioning in our Process of Becoming

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    There are estimated 10.4 million Filipinos living or working abroad primarily in the Middle East, Europe, Canada, and the United States searching for a better life for themselves and their families (Commission on Filipino Overseas, 2013). Due to economic motivation, assimilating to the host country\u27s culture, values, and traditions is an act of survival. While the majority of the research has focused on the domestic workers’ experience, rarely has there been a study focusing on Filipinos in the diaspora positive contributions to the host country and their Pilipinx Radical Imagination. As a result, the purpose of this qualitative study is to explore diasporic Filipinos’ current lived experiences and visioning for their communities. This study focuses on eight self identified Filipino/a/x/@, Pilipino/a/x/@ or Pin@y contributors from The Pilipinx Radical Imagination Reader (Nievera-Lozano & Santa Ana, 2018). This study utilizes Transcendent Resistance, a newly introduced framework, and FilCrit pedagogy and to examine their lived experiences and interview them with a culturally humble data collection methodology, kuwentuhan, sharing stories, (Jocson, 2008). Analysis of the data demonstrated three themes: (1) identity is culturally fluid; (2) transcendent love is at the heart of their love for themselves and their communities; (3) and healing and visioning. Further research is needed to document the positive contributions of Filipinos in the diaspora, complexities and multiplicities of Filipinos in the diaspora, community kuwentuhans as space for healing and visioning, and further development of the Pilipinx Radical Imagination

    Review of Top Quark Physics Results

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    As the heaviest known fundamental particle, the top quark has taken a central role in the study of fundamental interactions. Production of top quarks in pairs provides an important probe of strong interactions. The top quark mass is a key fundamental parameter which places a valuable constraint on the Higgs boson mass and electroweak symmetry breaking. Observations of the relative rates and kinematics of top quark final states constrain potential new physics. In many cases, the tests available with study of the top quark are both critical and unique. Large increases in data samples from the Fermilab Tevatron have been coupled with major improvements in experimental techniques to produce many new precision measurements of the top quark. The first direct evidence for electroweak production of top quarks has been obtained, with a resulting direct determination of VtbV_{tb}. Several of the properties of the top quark have been measured. Progress has also been made in obtaining improved limits on potential anomalous production and decay mechanisms. This review presents an overview of recent theoretical and experimental developments in this field. We also provide a brief discussion of the implications for further efforts.Comment: 119 pages, 55 figure
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