Author: "Ciaran Williams" - Searchworks@Jio Institute Digital Library Search Results

Your search keyword '"Ciaran Williams"' showing total 54 results

Start Over Author "Ciaran Williams"

54 results on '"Ciaran Williams"'

1. Pseudoscalar Higgs plus jet production at Next-to-Next-to-Leading Order in QCD

Author: Youngjin Kim and Ciaran Williams
Subjects: Higher-Order Perturbative Calculations, Higgs Production, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: Abstract We present a calculation of pseudoscalar Higgs production in association with a jet at Next-to-Next-to Leading Order (NNLO) accuracy in QCD. We work in an effective field theory in which m t → ∞ resulting in effective operators which couple the pseudoscalar to gluons and (massless) quarks. We have calculated all of the relevant amplitudes for the two-loop, one-loop and tree-level contributions. As a cross-check of our calculation we have re-calculated all of the scalar Higgs plus parton amplitudes and perform a detailed comparison to the literature. In order to regulate the infra-red singularities present at this order we employ the N-jettiness slicing method. In addition to a detailed validation of our calculation at this order we investigate LHC phenomenology for a selection of pseudoscalar Higgs masses. Our results are implemented into the parton-level Monte Carlo code MCFM.
Published: 2024
Full Text: View/download PDF

2. Four-jet event shapes in hadronic Higgs decays

Author: Aude Gehrmann-De Ridder, Christian T. Preuss, and Ciaran Williams
Subjects: Higher-Order Perturbative Calculations, Jets and Jet Substructure, Specific QCD Phenomenology, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: Abstract We present next-to-leading order perturbative QCD predictions for four-jet-like event-shape observables in hadronic Higgs decays. To this end, we take into account two Higgs-decay categories: involving either the Yukawa-induced decay to a $${\text{b}}\overline{{\text{b}} }$$ pair or the loop-induced decay to two gluons via an effective Higgs-gluon-gluon coupling. We present results for distributions related to the event-shape variables thrust minor, light-hemisphere mass, narrow jet broadening, D-parameter, and Durham four-to-three-jet transition variable. For each of these observables we study the impact of higher-order corrections and compare their size and shape in the two Higgs-decay categories. We find large NLO corrections with a visible shape difference between the two decay modes, leading to a significant shift of the peak in distributions related to the H → gg decay mode.
Published: 2024
Full Text: View/download PDF

3. Master integrals for electroweak corrections to $$gg\rightarrow \gamma \gamma $$ g g → γ γ : light quark contributions

Author: Gabriele Fiore and Ciaran Williams
Subjects: Astrophysics, QB460-466, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: Abstract We present a calculation of the master integrals (MI’s) required for the calculation of the Electroweak corrections to $$gg\rightarrow \gamma \gamma $$ g g → γ γ production in which the process contains a light quark loop. The integrals can be broken down into five categories based on the flow of the heavy vector bosons throughout the loop. Three of the families are planar, and two are non-planar. We determine a canonical basis for each family which allows an efficient solution of the resulting differential equations via iterated integrals. We calculate the families in relevant physical kinematics and obtain an efficient numerical evaluation based on an implementation of Chen-iterated integrals.
Published: 2023
Full Text: View/download PDF

4. Bottom-induced contributions to Higgs plus jet at next-to-next-to-leading order

Author: Roberto Mondini and Ciaran Williams
Subjects: Higgs Physics, Perturbative QCD, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: Abstract We present a next-to-next-to-leading order (NNLO) QCD calculation of the bottom-induced contributions to the production of a Higgs boson plus a jet, i.e. the process pp → H + j to O y b 2 α s 3 $$ \mathcal{O}\left({y}_b^2{\alpha}_s^3\right) $$ . We work in the five-flavor scheme (5FS) in which the bottom quark mass is retained only in the coupling to the Higgs boson. Our calculation uses N-jettiness slicing to regulate infrared divergences, allowing for fully-differential predictions for collider observables. After extensively validating the methodology, we present results for the 13 TeV LHC. Our NNLO predictions show a marked improvement in the overall renormalization and factorization scale dependence, the latter of which proves to be particularly troublesome for 5FS calculations at lower orders. In addition, using the same methodology we present a NNLO computation of b b ¯ $$ b\overline{b} $$ → H. Our results are implemented into MCFM.
Published: 2021
Full Text: View/download PDF

5. Top-induced contributions to H → b b ¯ $$ b\overline{b} $$ and H → c c ¯ $$ c\overline{c} $$ at O α s 3 $$ \mathcal{O}\left({\alpha}_s^3\right) $$

Author: Roberto Mondini, Ulrich Schubert, and Ciaran Williams
Subjects: Higgs Physics, Perturbative QCD, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: Abstract In this paper we present a fully-differential calculation for the contributions to the partial widths H → b b ¯ $$ b\overline{b} $$ and H → c c ¯ $$ c\overline{c} $$ that are sensitive to the top quark Yukawa coupling y t to order α s 3 $$ {\alpha}_s^3 $$ . These contributions first enter at order α s 2 $$ {\alpha}_s^2 $$ through terms proportional to y t y q (q = b, c). At order α s 3 $$ {\alpha}_s^3 $$ corrections to the mixed terms are present as well as a new contribution proportional to y t 2 $$ {y}_t^2 $$ . Our results retain the mass of the final-state quarks throughout, while the top quark is integrated out resulting in an effective field theory (EFT). Our results are implemented into a Monte Carlo code allowing for the application of arbitrary final-state selection cuts. As an example we present differential distributions for observables in the Higgs boson rest frame using the Durham jet clustering algorithm. We find that the total impact of the top-induced (i.e. EFT) pieces is sensitive to the nature of the final-state cuts, particularly b-tagging and c-tagging requirements. For bottom quarks, the EFT pieces contribute to the total width (and differential distributions) at around the percent level. The impact is much bigger for the H → c c ¯ $$ c\overline{c} $$ channel, with effects as large as 15%. We show however that their impact can be significantly reduced by the application of jet-tagging selection cuts.
Published: 2020
Full Text: View/download PDF

6. N3LO predictions for the decay of the Higgs boson to bottom quarks

Author: Roberto Mondini, Matthew Schiavi, and Ciaran Williams
Subjects: Higgs Physics, Perturbative QCD, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: Abstract We present a fully-differential calculation of the H → b b ¯ $$ H\to b\overline{b} $$ decay at next-to-next-to-next-to-leading order (N3LO) accuracy. Our calculation considers diagrams in which the Higgs boson couples directly to the bottom quarks, i.e. the perturbative order we consider is O α s 3 y b 2 $$ \mathcal{O}\left({\alpha}_s^3{y}_b^2\right) $$ . In order to regulate the infrared divergences present at this order we use the Projection-to-Born technique coupled with N -jettiness slicing. After validating our methodology at next-to-next-to-leading order (NNLO) we present exclusive jet rates and differential distributions for jet observables at N3LO accuracy using the Durham jet algorithm in the Higgs rest frame.
Published: 2019
Full Text: View/download PDF

7. H → b b ¯ j $$ H\to b\overline{b}j $$ at next-to-next-to-leading order accuracy

Author: Roberto Mondini and Ciaran Williams
Subjects: Jets, QCD Phenomenology, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: Abstract We present the calculation of the decay H → b b ¯ j $$ H\to b\overline{b}j $$ at next-to-next-to-leading order (NNLO) accuracy in QCD. We treat the bottom quarks as massless with a non-zero Higgs Yukawa coupling y b . We consider contributions in which the Higgs boson couples directly to bottom quarks, i.e. our predictions are accurate to order O α s 3 y b 2 $$ \mathcal{O}\left({\alpha}_s^3{y}_b^2\right) $$ . We calculate the various components needed to construct the NNLO contribution, including an independent calculation of the two-loop amplitudes. We compare our results for the two-loop amplitudes to an existing calculation finding agreement. We present additional checks on our two-loop expression using the known infrared factorization properties as the emitted gluon becomes soft or collinear. We use our results to construct a Monte Carlo implementation of H → b b ¯ j $$ H\to b\overline{b}j $$ and present jet rates and differential distributions in the Higgs rest frame using the Durham jet algorithm.
Published: 2019
Full Text: View/download PDF

8. Direct photon production and PDF fits reloaded

Author: John M. Campbell, Juan Rojo, Emma Slade, and Ciaran Williams
Subjects: Astrophysics, QB460-466, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: Abstract Direct photon production in hadronic collisions provides a handle on the gluon PDF by means of the QCD Compton scattering process. In this work we revisit the impact of direct photon production on a global PDF analysis, motivated by the recent availability of the next-to-next-to-leading (NNLO) calculation for this process. We demonstrate that the inclusion of NNLO QCD and leading-logarithmic electroweak corrections leads to a good quantitative agreement with the ATLAS measurements at 8 and 13 TeV, except for the most forward rapidity region in the former case. By including the ATLAS 8 TeV direct photon production data in the NNPDF3.1 NNLO global analysis, we assess its impact on the medium-x gluon. We also study the constraining power of the direct photon production measurements on PDF fits based on different datasets, in particular on the NNPDF3.1 no-LHC and collider-only fits. We also present updated NNLO theoretical predictions for direct photon production at 13 TeV that include the constraints from the 8 TeV measurements.
Published: 2018
Full Text: View/download PDF

9. The NNLO QCD soft function for 1-jettiness

Author: John M. Campbell, R. Keith Ellis, Roberto Mondini, and Ciaran Williams
Subjects: Astrophysics, QB460-466, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: Abstract We calculate the soft function for the global event variable 1-jettiness at next-to-next-to-leading order (NNLO) in QCD. We focus specifically on the non-Abelian contribution, which, unlike the Abelian part, is not determined by the next-to-leading order result. The calculation uses the known general forms for the emission of one and two soft partons and is performed using a sector-decomposition method that is spelled out in detail. Results are presented in the form of numerical fits to the 1-jettiness soft function for LHC kinematics (as a function of the angle between the incoming beams and the final-state jet) and for generic kinematics (as a function of three independent angles). These fits represent one of the needed ingredients for NNLO calculations that use the N-jettiness event variable to handle infrared singularities.
Published: 2018
Full Text: View/download PDF

10. Zγ production at NNLO including anomalous couplings

Author: John M. Campbell, Tobias Neumann, and Ciaran Williams
Subjects: QCD Phenomenology, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: Abstract In this paper we present a next-to-next-to-leading order (NNLO) QCD calculation of the processes pp → l + l −γ and pp→νν¯γ $$ pp\to \nu \overline{\nu}\gamma $$ that we have implemented in MCFM. Our calculation includes QCD corrections at NNLO both for the Standard Model (SM) and additionally in the presence of Zγγ and ZZγ anomalous couplings. We compare our implementation, obtained using the jettiness slicing approach, with a previous SM calculation and find broad agreement. Focusing on the sensitivity of our results to the slicing parameter, we show that using our setup we are able to compute NNLO cross sections with numerical uncertainties of about 0.1%, which is small compared to residual scale uncertainties of a few percent. We study potential improvements using two different jettiness definitions and the inclusion of power corrections. At s=13 $$ \sqrt{s}=13 $$ TeV we present phenomenological results and consider Zγ as a background to H → Zγ production. We find that, with typical cuts, the inclusion of NNLO corrections represents a small effect and loosens the extraction of limits on anomalous couplings by about 10%.
Published: 2017
Full Text: View/download PDF

11. N3LO predictions for the decay of the Higgs boson to bottom quarks

Author: Ciaran Williams, Matthew Schiavi, and Roberto Mondini
Subjects: Physics, Quark, Nuclear and High Energy Physics, Particle physics, Higgs Physics, High Energy Physics::Phenomenology, Perturbative QCD, Order (ring theory), FOS: Physical sciences, Observable, Rest frame, Jet (particle physics), High Energy Physics - Phenomenology, High Energy Physics - Phenomenology (hep-ph), Higgs boson, lcsh:QC770-798, High Energy Physics::Experiment, lcsh:Nuclear and particle physics. Atomic energy. Radioactivity
Abstract: We present a fully-differential calculation of the $H\rightarrow b\overline{b}$ decay at next-to-next- to-next-to-leading order (N$^3$LO) accuracy. Our calculation considers diagrams in which the Higgs boson couples directly to the bottom quarks, i.e. the perturbative order we consider is $\mathcal{O}(\alpha_s^3y_b^2)$. In order to regulate the infrared divergences present at this order we use the Projection-to-Born technique coupled with N-jettiness slicing. After validating our methodology at next-to-next-to-leading order (NNLO) we present exclusive jet rates and differential distributions for jet observables at N3LO accuracy using the Durham jet algorithm in the Higgs rest frame., Comment: 24 pages, 10 figures. v2 contains updated references and matches version submitted to journal
Published: 2019
Full Text: View/download PDF

12. Top-induced contributions to H → $$ b\overline{b} $$ and H → $$ c\overline{c} $$ at $$ \mathcal{O}\left({\alpha}_s^3\right) $$

Author: Ciaran Williams, Roberto Mondini, and Ulrich Schubert
Subjects: Physics, Quark, Nuclear and High Energy Physics, Top quark, Particle physics, 010308 nuclear & particles physics, Yukawa potential, Order (ring theory), Perturbative QCD, Rest frame, Coupling (probability), 01 natural sciences, 0103 physical sciences, Higgs boson, 010306 general physics
Abstract: In this paper we present a fully-differential calculation for the contributions to the partial widthsH →$$ b\overline{b} $$bb¯andH →$$ c\overline{c} $$cc¯that are sensitive to the top quark Yukawa couplingytto order$$ {\alpha}_s^3 $$αs3. These contributions first enter at order$$ {\alpha}_s^2 $$αs2through terms proportional toytyq(q=b, c). At order$$ {\alpha}_s^3 $$αs3corrections to the mixed terms are present as well as a new contribution proportional to$$ {y}_t^2 $$yt2. Our results retain the mass of the final-state quarks throughout, while the top quark is integrated out resulting in an effective field theory (EFT). Our results are implemented into a Monte Carlo code allowing for the application of arbitrary final-state selection cuts. As an example we present differential distributions for observables in the Higgs boson rest frame using the Durham jet clustering algorithm. We find that the total impact of the top-induced (i.e. EFT) pieces is sensitive to the nature of the final-state cuts, particularlyb-tagging andc-tagging requirements. For bottom quarks, the EFT pieces contribute to the total width (and differential distributions) at around the percent level. The impact is much bigger for theH →$$ c\overline{c} $$cc¯channel, with effects as large as 15%. We show however that their impact can be significantly reduced by the application of jet-tagging selection cuts.
Published: 2020
Full Text: View/download PDF

13. Erratum: Direct Photon Production at Next-to–Next-to-Leading Order [Phys. Rev. Lett. 118 , 222001 (2017)]

Author: Ciaran Williams, R. Keith Ellis, and John M. Campbell
Subjects: Physics, Particle physics, Photon, Order (business), Published Erratum, General Physics and Astronomy, Production (economics)
Published: 2020
Full Text: View/download PDF

14. Introduction to Perturbation Theory

Author: Ciaran Williams
Subjects: Theoretical physics, Collider physics, Computer science, Regularization (physics), Physics::Physics Education, Perturbation theory (quantum mechanics), Quantum field theory
Abstract: These lectures are designed to provide an introduction to perturbative techniques used to perform calculations for particle colliders. The aim of these lectures is to provide an overview (and starting point for further reading) of topics which are not typically covered as part of standard Quantum Field Theory graduate courses, but are nevertheless vital for modern applications of QFT for collider physics. Specifically the lectures will cover amplitude calculations using on-shell techniques at tree-level and one-loop, and tools for regularization of Infrared divergences at Next-to-Leading Order (NLO) and Next-to-Next-to Leading Order (NNLO).
Published: 2019
Full Text: View/download PDF

15. $$ H\to b\overline{b}j $$ at next-to-next-to-leading order accuracy

Author: Ciaran Williams and Roberto Mondini
Subjects: Quark, Physics, Quantum chromodynamics, Nuclear and High Energy Physics, Particle physics, 010308 nuclear & particles physics, Yukawa potential, Order (ring theory), Jet (particle physics), Coupling (probability), 01 natural sciences, Gluon, 0103 physical sciences, Higgs boson, 010306 general physics
Abstract: We present the calculation of the decay $$ H\to b\overline{b}j $$ H → b b ¯ j at next-to-next-to-leading order (NNLO) accuracy in QCD. We treat the bottom quarks as massless with a non-zero Higgs Yukawa coupling y b . We consider contributions in which the Higgs boson couples directly to bottom quarks, i.e. our predictions are accurate to order $$ \mathcal{O}\left({\alpha}_s^3{y}_b^2\right) $$ O α s 3 y b 2 . We calculate the various components needed to construct the NNLO contribution, including an independent calculation of the two-loop amplitudes. We compare our results for the two-loop amplitudes to an existing calculation finding agreement. We present additional checks on our two-loop expression using the known infrared factorization properties as the emitted gluon becomes soft or collinear. We use our results to construct a Monte Carlo implementation of $$ H\to b\overline{b}j $$ H → b b ¯ j and present jet rates and differential distributions in the Higgs rest frame using the Durham jet algorithm.
Published: 2019
Full Text: View/download PDF

16. Direct photon production and PDF fits reloaded

Author: Ciaran Williams, John M. Campbell, Emma Slade, Juan Rojo, and (Astro)-Particles Physics
Subjects: Particle physics, Photon, Physics and Astronomy (miscellaneous), Hadron, Nuclear Theory, FOS: Physical sciences, lcsh:Astrophysics, 7. Clean energy, 01 natural sciences, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), High Energy Physics - Phenomenology (hep-ph), 0103 physical sciences, lcsh:QB460-466, Rapidity, lcsh:Nuclear and particle physics. Atomic energy. Radioactivity, 010306 general physics, Engineering (miscellaneous), Quantum chromodynamics, Physics, 010308 nuclear & particles physics, hep-ex, Electroweak interaction, High Energy Physics::Phenomenology, Compton scattering, hep-ph, SDG 10 - Reduced Inequalities, Gluon, High Energy Physics - Phenomenology, lcsh:QC770-798, High Energy Physics::Experiment, Regular Article - Theoretical Physics
Abstract: Direct photon production in hadronic collisions provides a handle on the gluon PDF by means of the QCD Compton scattering process. In this work we revisit the impact of direct photon production on a global PDF analysis, motivated by the recent availability of the next-to-next-to-leading (NNLO) calculation for this process. We demonstrate that the inclusion of NNLO QCD and leading-logarithmic electroweak corrections leads to a good quantitative agreement with the ATLAS measurements at 8 TeV and 13 TeV, except for the most forward rapidity region in the former case. By including the ATLAS 8 TeV direct photon production data in the NNPDF3.1 NNLO global analysis, we assess its impact on the medium-x gluon. We also study the constraining power of the direct photon production measurements on PDF fits based on different datasets, in particular on the NNPDF3.1 no-LHC and collider-only fits. We also present updated NNLO theoretical predictions for direct photon production at 13 TeV that include the constraints from the 8 TeV measurements., Comment: 27 pages, 14 figures. Version accepted for publication in EPJC
Published: 2018
Full Text: View/download PDF

17. Zγ production at NNLO including anomalous couplings

Author: Ciaran Williams, Tobias Neumann, and John M. Campbell
Subjects: Quantum chromodynamics, Physics, Nuclear and High Energy Physics, Particle physics, 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, Order (ring theory), Scale (descriptive set theory), QCD Phenomenology, Residual, 01 natural sciences, High Energy Physics - Experiment, Standard Model, High Energy Physics - Phenomenology, 0103 physical sciences, lcsh:QC770-798, lcsh:Nuclear and particle physics. Atomic energy. Radioactivity, Production (computer science), Sensitivity (control systems), 010306 general physics
Abstract: In this paper we present a next-to-next-to-leading order (NNLO) QCD calculation of the processes $pp\rightarrow l^+l^-\gamma$ and $pp\rightarrow \nu\bar\nu\gamma$ that we have implemented in MCFM. Our calculation includes QCD corrections at NNLO both for the Standard Model (SM) and additionally in the presence of $Z\gamma\gamma$ and $ZZ\gamma$ anomalous couplings. We compare our implementation, obtained using the jettiness slicing approach, with a previous SM calculation and find broad agreement. Focusing on the sensitivity of our results to the slicing parameter, we show that using our setup we are able to compute NNLO cross sections with numerical uncertainties of about $0.1\%$, which is small compared to residual scale uncertainties of a few percent. We study potential improvements using two different jettiness definitions and the inclusion of power corrections. At $\sqrt{s}=13$ TeV we present phenomenological results and consider $Z\gamma$ as a background to $H\to Z\gamma$ production. We find that, with typical cuts, the inclusion of NNLO corrections represents a small effect and loosens the extraction of limits on anomalous couplings by about $10\%$., Comment: 30 pages, 14 figures
Published: 2017
Full Text: View/download PDF

18. Driving missing data at the LHC: NNLO predictions for the ratio ofγ+jandZ+j

Author: John M. Campbell, R. Keith Ellis, and Ciaran Williams
Subjects: Quantum chromodynamics, Physics, Particle physics, Large Hadron Collider, Photon, 010308 nuclear & particles physics, Physics beyond the Standard Model, Electroweak interaction, Dark matter, Supersymmetry, 01 natural sciences, Vector boson, 0103 physical sciences, 010306 general physics
Abstract: In this paper, we present a calculation of the γ+j process at next-to-next-to-leading order (NNLO) in QCD and compare the resulting predictions to 8 TeV CMS data. We find good agreement with the shape of the photon pT spectrum, particularly after the inclusion of additional electroweak corrections, but there is a tension between the overall normalization of the theoretical prediction and the measurement. We use our results to compute the ratio of Z(→l+l−)+j to γ+j events as a function of the vector boson transverse momentum at NNLO, a quantity that is used to normalize Z(→νν¯)+j backgrounds in searches for dark matter and supersymmetry. Our NNLO calculation significantly reduces the theoretical uncertainty on this ratio, thus boosting its power for future searches of new physics.
Published: 2017
Full Text: View/download PDF

19. Direct Photon Production at Next-to-Next-to-Leading Order

Author: R. Keith Ellis, Ciaran Williams, and John M. Campbell
Subjects: Quantum chromodynamics, Physics, Particle physics, Photon, 010308 nuclear & particles physics, Electroweak interaction, High Energy Physics::Phenomenology, General Physics and Astronomy, FOS: Physical sciences, Parton, Kinematics, 01 natural sciences, Vector boson, High Energy Physics - Experiment, High Energy Physics - Phenomenology, High Energy Physics - Experiment (hep-ex), High Energy Physics - Phenomenology (hep-ph), 0103 physical sciences, Gravitational singularity, High Energy Physics::Experiment, 010306 general physics, Boson
Abstract: We present the first calculation of direct photon production at next-to-next-to leading order (NNLO) accuracy in QCD. For this process, although the final state cuts mandate only the presence of a single electroweak boson, the underlying kinematics resembles that of a generic vector boson plus jet topology. In order to regulate the infrared singularities present at this order we use the $N$-jettiness slicing procedure, applied for the first time to a final state that at Born level includes colored partons but no required jet. We compare our predictions to ATLAS 8 TeV data and find that the inclusion of the NNLO terms in the perturbative expansion, supplemented by electroweak corrections, provides an excellent description of the data with greatly reduced theoretical uncertainties., Comment: 6 pages, 5 figures
Published: 2017

20. Higgs bosons at high pT

Author: Tobias Neumann and Ciaran Williams
Subjects: Physics, Particle physics, Scale (ratio), 010308 nuclear & particles physics, High Energy Physics::Phenomenology, Order (ring theory), 01 natural sciences, Cross section (physics), Amplitude, Monte carlo code, 0103 physical sciences, Higgs boson, Nuclear Experiment, 010306 general physics, Asymptotic expansion, Boson
Abstract: We present a calculation of $H+j$ at NLO including the effect of a finite top-mass. Where possible we include the complete dependence on $m_t$. This includes the leading order amplitude, the infrared poles of the two-loop amplitude and the real radiation amplitude. The remaining finite piece of the virtual correction is considered in an asymptotic expansion in $m_t$, which is accurate to $m_t^{-4}$. By successively including more $m_t$-exact pieces, the dependence on the asymptotic series diminishes and we find convergent behavior for $p_T^H>m_t$ for the first time. Our results justify rescaling by the $m_t$-exact LO cross section to model top-mass effects in EFT results up to $p_T$ of 250 to 300 GeV. We show that the error made by using the LO rescaling becomes comparable to the NNLO scale uncertainty for such large energies. We implement our results into the Monte Carlo code MCFM.
Published: 2017
Full Text: View/download PDF

21. The NNLO QCD soft function for 1-jettiness

Author: Roberto Mondini, John M. Campbell, R. Keith Ellis, and Ciaran Williams
Subjects: Quantum chromodynamics, Physics, Particle physics, Physics and Astronomy (miscellaneous), 010308 nuclear & particles physics, FOS: Physical sciences, lcsh:Astrophysics, Parton, Function (mathematics), Kinematics, Jet (particle physics), 01 natural sciences, High Energy Physics - Phenomenology, High Energy Physics - Phenomenology (hep-ph), lcsh:QB460-466, 0103 physical sciences, lcsh:QC770-798, lcsh:Nuclear and particle physics. Atomic energy. Radioactivity, Gravitational singularity, 010306 general physics, Engineering (miscellaneous), Event (particle physics), Variable (mathematics)
Abstract: We calculate the soft function for the global event variable 1-jettiness at next-to-next-to-leading order (NNLO) in QCD. We focus specifically on the non-Abelian contribution, which, unlike the Abelian part, is not determined by the next-to-leading order result. The calculation uses the known general forms for the emission of one and two soft partons and is performed using a sector-decomposition method that is spelled out in detail. Results are presented in the form of numerical fits to the 1-jettiness soft function for LHC kinematics (as a function of the angle between the incoming beams and the final-state jet) and for generic kinematics (as a function of three independent angles). These fits represent one of the needed ingredients for NNLO calculations that use the N-jettiness event variable to handle infrared singularities., Comment: 42 pages, 7 figures
Published: 2017
Full Text: View/download PDF

22. The Higgs boson at high pT: Finite top-mass improved results

Author: Ciaran Williams and Tobias Neumann
Subjects: Physics, Higgs field, Particle physics, Higgs boson, Elementary particle, Asymptotic expansion
Published: 2016
Full Text: View/download PDF

23. Predictions for diphoton production at the LHC through NNLO in QCD

Author: Ciaran Williams, John M. Campbell, Ye Li, and R. Keith Ellis
Subjects: Quantum chromodynamics, Physics, Nuclear and High Energy Physics, Particle physics, 010308 nuclear & particles physics, Physics beyond the Standard Model, High Energy Physics::Phenomenology, FOS: Physical sciences, Order (ring theory), Context (language use), Parton, Fermion, 01 natural sciences, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), High Energy Physics - Phenomenology, High Energy Physics - Phenomenology (hep-ph), 0103 physical sciences, High Energy Physics::Experiment, Production (computer science), Invariant mass, 010306 general physics
Abstract: In this paper we present a next-to-next-to-leading order (NNLO) calculation of the process $pp\rightarrow \gamma\gamma$ that we have implemented into the parton level Monte Carlo code MCFM. We do not find agreement with the previous calculation of this process in the literature. In addition to the $\mathcal{O}(\alpha_s^2)$ corrections present at NNLO, we include some effects arising at $\mathcal{O}(\alpha_s^3)$, namely those associated with gluon-initiated closed fermion loops. We investigate the role of this process in the context of studies of QCD at colliders and as a background for searches for new physics, paying particular attention to the diphoton invariant mass spectrum. We demonstrate that the NNLO QCD prediction for the shape of this spectrum agrees well with functional forms used in recent data-driven fits., Comment: 28 Pages, 11 Figures, Corrected Typo in Appendix A
Published: 2016
Full Text: View/download PDF

24. Associated production of a Higgs boson at NNLO

Author: Ciaran Williams, John M. Campbell, and R. Keith Ellis
Subjects: Condensed Matter::Quantum Gases, Physics, Quantum chromodynamics, Nuclear and High Energy Physics, Particle physics, 010308 nuclear & particles physics, High Energy Physics::Phenomenology, FOS: Physical sciences, Fermion, 01 natural sciences, High Energy Physics - Experiment, Vector boson, High Energy Physics - Experiment (hep-ex), High Energy Physics - Phenomenology, High Energy Physics - Phenomenology (hep-ph), Phase space, 0103 physical sciences, Higgs boson, High Energy Physics::Experiment, 010306 general physics, Phenomenology (particle physics), Boson, Lepton
Abstract: In this paper we present a Next-to-Next-to Leading Order (NNLO) calculation of the production of a Higgs boson in association with a massive vector boson. We include the decays of the unstable Higgs and vector bosons, resulting in a fully flexible parton-level Monte Carlo implementation. We also include all $\mathcal{O}(\alpha_s^2)$ contributions that occur in production for these processes: those mediated by the exchange of a single off-shell vector boson in the $s$-channel, and those which arise from the coupling of the Higgs boson to a closed loop of fermions. We study final states of interest for Run II phenomenology, namely $H\rightarrow b\bar{b}$, $\gamma\gamma$ and $WW^*$. The treatment of the $H\rightarrow b\bar{b}$ decay includes QCD corrections at NLO. We use the recently developed $N$-jettiness regularization procedure, and study its viability in the presence of a large final-state phase space by studying $pp\rightarrow V(H\rightarrow WW^*) \rightarrow$ leptons., Comment: 31 pages, 16 Figues, 3 Tables : v2 Matches published version
Published: 2016

25. Color singlet production at NNLO in MCFM

Author: Christfried Focke, Xiaohui Liu, R. Keith Ellis, Frank Petriello, John M. Campbell, Radja Boughezal, Ciaran Williams, and Walter T. Giele
Subjects: Quantum chromodynamics, Physics, Particle physics, Physics and Astronomy (miscellaneous), 010308 nuclear & particles physics, Monte Carlo method, High Energy Physics::Phenomenology, FOS: Physical sciences, 01 natural sciences, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), High Energy Physics - Phenomenology, High Energy Physics - Phenomenology (hep-ph), Monte carlo code, Regularization (physics), 0103 physical sciences, 010306 general physics, Engineering (miscellaneous), Boson
Abstract: We present the implementation of several color-singlet final-state processes at Next-to-Next-to Leading Order (NNLO) accuracy in QCD to the publicly available parton-level Monte Carlo program MCFM. Specifically we discuss the processes $pp\rightarrow H$, $pp\rightarrow Z$, $pp\rightarrow W$, $pp\rightarrow HZ$, $pp\rightarrow HW$ and $pp\rightarrow\gamma\gamma$. Decays of the unstable bosons are fully included, resulting in a flexible fully differential Monte Carlo code. The NNLO corrections have been calculated using the non-local $N$-jettiness subtraction approach. Special attention is given to the numerical aspects of running MCFM for these processes at this order. We pay particular attention to the systematic uncertainties due to the power corrections induced by the $N$-jettiness regularization scheme and the evaluation time needed to run the hybrid openMP/MPI version of MCFM at NNLO on multi-processor systems., Comment: 31 pages, 10 figures, 11 Tables, Code can be downloaded html://mcfm.fnal.gov
Published: 2016

26. γγγγproduction at the LHC: An application of2→4analytic unitarity

Author: Tristan Dennen and Ciaran Williams
Subjects: Quantum chromodynamics, Physics, Nuclear and High Energy Physics, Particle physics, Photon, Large Hadron Collider, Unitarity, Astrophysics::High Energy Astrophysical Phenomena, Monte Carlo method, Double-precision floating-point format, Gamma gamma
Abstract: We present Next-to-Leading Order (NLO) predictions for $\gamma\gamma\gamma\gamma$ final states, including the effects of photon fragmentation. Our results are calculated fully analytically using the techniques of $D$-dimensional unitarity, and we discuss some refinements to existing methods, focusing particularly on the role of three-mass triangle coefficients. Using these techniques we are able to produce a numerically stable Monto Carlo code that runs fully in double precision. We investigate the $4\gamma$ signal at colliders, both for Run II of the LHC and at future machines. Our results are implemented in MCFM.
Published: 2015
Full Text: View/download PDF

27. Higher Order QCD predictions for Associated Higgs production with anomalous couplings to gauge bosons

Author: Ciaran Williams, Ken Mimasu, and Veronica Sanz
Subjects: Physics, Quantum chromodynamics, Particle physics, Gauge boson, Nuclear and High Energy Physics, 010308 nuclear & particles physics, Physics beyond the Standard Model, Electroweak interaction, High Energy Physics::Phenomenology, FOS: Physical sciences, 01 natural sciences, High Energy Physics - Experiment, High Energy Physics - Phenomenology, High Energy Physics - Experiment (hep-ex), High Energy Physics - Phenomenology (hep-ph), 0103 physical sciences, Higgs boson, Effective field theory, High Energy Physics::Experiment, Symmetry breaking, 010306 general physics, QC, Boson
Abstract: We present predictions for the associated production of a Higgs boson at NLO+PS accuracy, including the effect of anomalous interactions between the Higgs and gauge bosons. We present our results in different frameworks, one in which the interaction vertex between the Higgs boson and Standard Model $W$ and $Z$ bosons is parameterized in terms of general Lorentz structures, and one in which Electroweak symmetry breaking is manifestly linear and the resulting operators arise through a six-dimensional effective field theory framework. We present analytic calculations of the Standard Model and Beyond the Standard Model contributions, and discuss the phenomenological impact of the higher order pieces. Our results are implemented in the NLO Monte Carlo program MCFM, and interfaced to shower Monte Carlos through the {\sc Powheg} box framework., Comment: 24 pages, 10 figures, v2 matches published version, includes fixes to figures and text and added discussion of effect of the EFT operators on EW parameters
Published: 2015
Full Text: View/download PDF

28. Closing up on Dark Sectors at Colliders: from 14 to 100 TeV

Author: Michael Spannowsky, Philip Harris, Valentin V. Khoze, and Ciaran Williams
Subjects: Particle physics, Physics beyond the Standard Model, Astrophysics::High Energy Astrophysical Phenomena, Dark matter, Scalar (mathematics), FOS: Physical sciences, Parton, Parameter space, 01 natural sciences, law.invention, High Energy Physics - Experiment, Nuclear physics, High Energy Physics - Experiment (hep-ex), High Energy Physics - Phenomenology (hep-ph), law, 0103 physical sciences, 010306 general physics, Collider, Particle Physics - Phenomenology, Physics, Large Hadron Collider, 010308 nuclear & particles physics, High Energy Physics::Phenomenology, Pseudoscalar, High Energy Physics - Phenomenology, High Energy Physics::Experiment
Abstract: We investigate the reach of the LHC Run 2 and that of a future circular hadron collider with up to 100 TeV centre of mass energy for the exploration of potential Dark Matter sectors. These dark sectors are conveniently and broadly described by simplified models. The simplified models we consider provide microscopic descriptions of interactions between the Standard Model partons and the dark sector particles mediated by the four basic types of messenger fields: scalar, pseudo-scalar, vector or axial-vector. Our analysis extends and updates the previously available results for the LHC at 8 and 14 TeV to 100 TeV for models with all four messenger types. We revisit and improve the analysis at 14 TeV, by studying a variety of analysis techniques, concluding that the most discriminating variables correspond to the missing transverse energy and the azimuthal angle between jets in the final state. Going to 100 TeV, the limits on simplified models of Dark Matter are enhanced significantly, in particular for heavier mediators and dark sector particles, for which the available phase space at the LHC is restricted. The possibility of a 100 TeV collider provides an unprecedented coverage of the dark sector basic parameters and a unique opportunity to pin down the particle nature of Dark Matter and its interactions with the Standard Model., Comment: 16 pages, 11 figures
Published: 2015
Full Text: View/download PDF

29. Constraining Dark Sectors at Colliders: Beyond the Effective Theory Approach

Author: Valentin V. Khoze, Ciaran Williams, Philip Harris, and Michael Spannowsky
Subjects: Physics, Nuclear and High Energy Physics, Particle physics, Top quark, Large Hadron Collider, Physics beyond the Standard Model, Dark matter, Scalar (mathematics), High Energy Physics::Phenomenology, FOS: Physical sciences, High Energy Physics - Experiment, Hidden sector, Pseudoscalar, High Energy Physics - Experiment (hep-ex), High Energy Physics - Phenomenology, High Energy Physics - Phenomenology (hep-ph), Effective field theory, Particle Physics - Phenomenology
Abstract: We outline and investigate a set of benchmark simplified models with the aim of providing a minimal simple framework for an interpretation of the existing and forthcoming searches of dark matter particles at the LHC. The simplified models we consider provide microscopic QFT descriptions of interactions between the Standard Model partons and the dark sector particles mediated by the four basic types of messenger fields: scalar, pseudo-scalar, vector or axial-vector. Our benchmark models are characterised by four to five parameters, including the mediator mass and width, the dark matter mass and an effective coupling(s). In the gluon fusion production channel we resolve the top-quark in the loop and compute full top-mass effects for scalar and pseudo-scalar messengers. We show the LHC limits and reach at 8 and 14 TeV for models with all four messenger types. We also outline the complementarity of direct detection, indirect detection and LHC bounds for dark matter searches. Finally, we investigate the effects which arise from extending the simplified model to include potential new physics contributions in production. Using the scalar mediator as an example we study the impact of heavy new physics loops which interfere with the top mediated loops. Our computations are performed within the MCFM framework and we provide fully flexible public Monte Carlo implementation., 19 pages, 12 figures : v2 contains updated plots after bug fix in the application of the jet-veto, and new plots related to pseudo-scalar mediators, additional references have been included
Published: 2014
Full Text: View/download PDF

30. Bounding the Higgs width at the LHC using full analytic results for gg → e − e + μ − μ +

Author: R. Keith Ellis, Ciaran Williams, and John M. Campbell
Subjects: Quark, Physics, Nuclear and High Energy Physics, Particle physics, Large Hadron Collider, Hadron, High Energy Physics::Phenomenology, Higgs boson, Invariant mass, High Energy Physics::Experiment, Helicity, Boson, Gluon
Abstract: We revisit the hadronic production of the four-lepton final state, e − e + μ − μ + , through the fusion of initial state gluons. This process is mediated by loops of quarks and we provide first full analytic results for helicity amplitudes that account for both the effects of the quark mass in the loop and off-shell vector bosons. The analytic results have been implemented in the Monte Carlo program MCFM and are both fast, and numerically stable in the region of low Z transverse momentum. We use our results to study the interference between Higgs-mediated and continuum production of four-lepton final states, which is necessary in order to obtain accurate theoretical predictions outside the Higgs resonance region. We have confirmed and extended a recent analysis of Caola and Melnikov that proposes to use a measurement of the off-shell region to constrain the total width of the Higgs boson. Using a simple cut-and-count method, existing LHC data should bound the width at the level of 25–45 times the Standard Model expectation. We investigate the power of using a matrix element method to construct a kinematic discriminant to sharpen the constraint. In our analysis the bound on the Higgs width is improved by a factor of about 1 . 6 using a simple cut on the MEM discriminant, compared to an invariant mass cut m 4 l > 300 GeV.
Published: 2014

31. Event by event weighting at NLO

Author: John M. Campbell, Ciaran Williams, and Walter T. Giele
Subjects: Computer science, Event (relativity), Data mining, computer.software_genre, computer, Weighting
Published: 2014
Full Text: View/download PDF

32. Bounding the Higgs width at the LHC: Complementary results fromH→WW

Author: Ciaran Williams, John M. Campbell, and R. Keith Ellis
Subjects: Physics, Systematic error, Nuclear and High Energy Physics, Particle physics, Large Hadron Collider, High Energy Physics::Phenomenology, FOS: Physical sciences, Nuclear physics, High Energy Physics - Phenomenology, High Energy Physics - Phenomenology (hep-ph), Bounding overwatch, Atlas data, Higgs boson, Transverse mass
Abstract: We investigate the potential of the process $gg \to H \to WW$ to provide bounds on the Higgs width. Recent studies using off-shell $H\rightarrow ZZ$ events have shown that Run 1 LHC data can constrain the Higgs width, $\Gamma_H < (25-45) \Gamma_{H}^{\rm SM}$. Using 20 fb-1 of 8 TeV ATLAS data, we estimate a bound on the Higgs boson width from the WW channel between $\Gamma_H < (100-500) \Gamma_H^{SM}$. The large spread in limits is due to the range of cuts applied in the existing experimental analysis. The stricter cuts designed to search for the on-shell Higgs boson limit the potential number of off-shell events, weakening the constraints. As some of the cuts are lifted the bounds improve. We show that there is potential in the high transverse mass region to produce upper bounds of the order of $(25-50) \Gamma_H^{SM}$, depending strongly on the level of systematic uncertainty that can be obtained. Thus, if these systematics can be controlled, a constraint on the Higgs boson width from the $H \to WW$ decay mode can complement a corresponding limit from $H \to ZZ$., Comment: 8 pages, 5 figures
Published: 2014
Full Text: View/download PDF

33. Triphoton production at hadron colliders

Author: Ciaran Williams and John M. Campbell
Subjects: Physics, Nuclear and High Energy Physics, Particle physics, Large Hadron Collider, Photon, Monte Carlo method, Hadron, Tevatron, FOS: Physical sciences, High Energy Physics - Experiment, Nuclear physics, High Energy Physics - Experiment (hep-ex), High Energy Physics - Phenomenology, Amplitude, High Energy Physics - Phenomenology (hep-ph), Monte carlo code, Fragmentation function
Abstract: We present next-to-leading order predictions for the production of triphoton final states at the LHC and the Tevatron. Our results include the effect of photon fragmentation for the first time and we are able to quantify the impact of different isolation prescriptions. We find that calculations accounting for fragmentation effects at leading order, and those employing a smooth cone isolation where no fragmentation contribution is required, are in reasonable agreement with one another. However, larger differences in the predicted rates arise when higher order corrections to the fragmentation functions are included. In addition we present full analytic results for the $\gamma\gamma\gamma$ and $\gamma\gamma+$jet one-loop amplitudes. These amplitudes, which are particularly compact, may be useful to future higher-order calculations. Our results are available in the Monte Carlo code MCFM., Comment: 16 pages, 4 figures
Published: 2014

34. Working Group Report: Computing for Perturbative QCD

Author: Frank Petriello, Laura Reina, Doreen Wackeroth, Radja Boughezal, Pavel M. Nadolsky, Christian Bauer, Alexander Mitov, Fredrick I. Olness, Jonathan R. Walsh, Markus Wobisch, Junichi Kanzaki, Stefano Pozzorini, John Campbell, Zvi Bern, Thomas Gehrmann, Neil D. Christensen, Michael E. Peskin, Ciaran Williams, Frank Siegert, Lance J. Dixon, and Stefan Höche
Subjects: Physics, Particle physics, Chiral perturbation theory, Grid computing, Group (mathematics), Monte Carlo method, Bibliography, Perturbative QCD, computer.software_genre, Stability (probability), computer
Published: 2013
Full Text: View/download PDF

35. A literature review reveals that trials evaluating treatment of non-specific low back pain use inconsistent criteria to identify serious pathologies and nerve root involvement

Author: Mark J. Hancock, Christopher G. Maher, Paulo H. Ferreira, Ciaran Williams, and Manuela L. Ferreira
Subjects: Sciatica, medicine.medical_specialty, Nerve root, business.industry, Alternative medicine, Psychological intervention, Physical Therapy, Sports Therapy and Rehabilitation, Low back pain, law.invention, Randomized controlled trial, Non specific, law, medicine, Physical therapy, Original Article, medicine.symptom, Medline database, business
Abstract: The broad aim of this study was to assess the homogeneity of patients included in trials of non-specific low back pain (NSLBP). To do this, we investigated the consistency and clarity of criteria used to identify and exclude participants with serious pathologies and nerve root compromise in randomized controlled trials, investigating interventions for NSLBP.We searched Medline database for randomized controlled trials of low back pain (LBP). published between 2000 and 2009. We then randomly selected and screened trials for inclusion until we had 50 eligible trials. Data were extracted on the criteria used to identify cases of serious conditions (e.g. cancer, fracture) and nerve root involvement.The majority of papers (35/50) explicitly excluded patients with serious pathology. However, the terminology used and examples given were highly variable. Nerve root involvement was an exclusion criterion in the majority but not all studies. The criteria used for excluding patients with nerve root involvement varied greatly between studies. The most common criteria were 'motor, sensory or reflex changes' (nine studies), followed by 'pain radiating below the knee' (five studies) and 'reduced straight leg raise which reproduces leg pain' (five studies). In half of the included studies, the criteria used, while alluding to nerve root involvement, were not explained adequately for us to determine the types of patients included or excluded.The inconsistent and unclear criteria used to identify cases of serious pathology and nerve root compromise means that published trials of LBP likely include heterogeneous patient populations. This trait limits our ability to make comparisons across trials or pool studies. Standardization and consensus is important for future research.
Published: 2013

36. Finding the Higgs boson in decays toZγusing the matrix element method at next-to-leading order

Author: Walter T. Giele, John M. Campbell, Ciaran Williams, and R. Keith Ellis
Subjects: Physics, Nuclear and High Energy Physics, Particle physics, FOS: Physical sciences, Order (ring theory), Elementary particle, State (functional analysis), High Energy Physics - Experiment, Luminosity, High Energy Physics - Phenomenology, High Energy Physics - Experiment (hep-ex), High Energy Physics - Phenomenology (hep-ph), Higgs boson, Production (computer science), Invariant mass, Event (particle physics)
Abstract: We illustrate how the Matrix Element Method at Next-to-Leading Order (MEM@NLO) can be used to discriminate between events arising from the production of a Higgs boson, which subsequently decays to a final state consisting of ell^+ell^-gamma, and the background production of the same final state. We illustrate how the method could be used in an experimental analysis by devising cuts on the signal (P_S) and background (P_B) weights that are computed event-by-event in this approach. We find that we can increase the S/sqrt(B) ratio by around 50\% compared to an invariant mass fit on its own. Considering only statistical uncertainty, this is equivalent to recording a factor of around two times more integrated luminosity., Comment: 9 pages, 2 figures
Published: 2013
Full Text: View/download PDF

37. Next-to-leading order predictions for dark matter production at hadron colliders

Author: Ciaran Williams and Patrick J. Fox
Subjects: Quantum chromodynamics, Physics, Nuclear and High Energy Physics, Particle physics, Physics beyond the Standard Model, Monte Carlo method, Dark matter, Hadron, Scalar (mathematics), FOS: Physical sciences, Jet (particle physics), High Energy Physics - Experiment, Standard Model, Nuclear physics, High Energy Physics - Experiment (hep-ex), High Energy Physics - Phenomenology, High Energy Physics - Phenomenology (hep-ph), High Energy Physics::Experiment
Abstract: We provide Next-to-Leading Order (NLO) predictions for Dark Matter (DM) production in association with either a jet or a photon at hadron colliders. In particular we study the production of a pair of fermionic DM particles through a mediator which couples to SM via either a vector, axial-vector, scalar, pseudo-scalar, or gluon-induced coupling. Experimental constraints on the scale of new physics associated with these operators are limited by systematics, highlighting the need for NLO signal modeling. We factorize the NLO QCD and the DM parts of the calculation, allowing the possibility of using the results presented here for a large variety of searches in monojet and monophoton final states. Our results are implemented into the Monte Carlo program MCFM., 23 Pages, 10 Figures
Published: 2013
Full Text: View/download PDF

38. Next-to-leading order predictions for a lepton, missing transverse momentum, and dijets at the Tevatron

Author: Ciaran Williams, John M. Campbell, and Adam Martin
Subjects: Nuclear physics, Semileptonic decay, Physics, Nuclear and High Energy Physics, Particle physics, Bar (music), High Energy Physics::Phenomenology, Transverse momentum, Tevatron, Order (ring theory), High Energy Physics::Experiment, Invariant mass, Lepton
Abstract: In this paper we investigate the various processes that can contribute to a final state consisting of a lepton, missing transverse momentum, and two jets at next-to-leading order (NLO) at the Tevatron. In particular we consider the production of W/Z+2 jets, diboson pairs, single top, and the t{bar t} process with both fully leptonic and semileptonic decays. We present distributions for the invariant mass of the dijet system and normalizations of the various processes, accurate to NLO.
Published: 2011
Full Text: View/download PDF

39. Gluon-gluon contributions to W+ W- production and Higgs interference effects

Author: Ciaran Williams, John M. Campbell, and R. Keith Ellis
Subjects: Physics, Quark, Particle physics, Nuclear and High Energy Physics, Large Hadron Collider, High Energy Physics::Phenomenology, Tevatron, FOS: Physical sciences, Expected value, High Energy Physics - Experiment, Gluon, Massless particle, High Energy Physics - Phenomenology, High Energy Physics - Experiment (hep-ex), High Energy Physics - Phenomenology (hep-ph), Higgs boson, Transverse mass, High Energy Physics::Experiment
Abstract: In this paper we complete our re-assessment of the production of W boson pairs at the LHC, by calculating analytic results for the gg -> W+ W- -> (��l l��) process including the effect of massive quarks circulating in the loop. Together with the one-loop amplitudes containing the first two generations of massless quarks propagating in the loop, these diagrams can give a significant contribution with a large flux of gluons. One of the component parts of this calculation is the production of a standard model Higgs boson, gg -> H and its subsequent decay, H -> W+(-> ��l) W-(-> l ��). We will quantify the importance of the interference between the Higgs boson production process and the gluon-induced continuum production in the context of searches for the Higgs boson at the Tevatron and the LHC. For instance, for mH < 140 GeV the effect of the interference typically results in around a 10% reduction in the expected number of Higgs signal events. The majority of this interference is due to non-resonant contributions. Therefore cuts on the transverse mass such as those currently used by the ATLAS collaboration reduce the destructive interference to about a 1% effect. We advocate that a cut on the maximum transverse mass be used in future Higgs searches in this channel.
Published: 2011
Full Text: View/download PDF

40. Isotopic Composition of Light Nuclei in Cosmic Rays: Results from AMS-01

Author: H. T. Liu, J. Ulbricht, P. Extermann, H. Hofer, G. Ambrosi, U. Becker, E. Perrin, C. Sbarra, W. J. Burger, F. J. Eppling, P. H. Fisher, S. M. Ting, M. Kraeber, Rui Miguel Faisca Rodrigues Pereira, Veronica Bindi, T. Kirn, M. Paniccia, C. dela Guia, A. Klimentov, Adrian Biland, M.W. Lee, M. Pimenta, Jouko Ritakari, Hui Zhang, S. Schael, I. D'Antone, D. Rapin, Sadakazu Haino, J. Casaus, Massimo Gervasi, Jungwook Shin, V. Plyaskin, P. Azzarello, F. Mayet, A. Schultz von Dratzig, D. Grandi, Andrea Contin, J.V. Allaby, L. Djambazov, Andrei Kounine, P. G. Rancoita, M. Pohl, B. Bertucci, Xiao-Dong Tang, J. P. Vialle, W.Z. Zhu, M. Capell, R. Siedling, Shih-Chang Lee, H. Park, L. Ao, J. Engelberg, M. Jongmanns, R. Kossakowski, H. von Gunten, D. Crespo, J. D. Burger, K. Lübelsmeyer, J. Alcaraz, K. Karlamaa, Yun-Young Choi, S. X. Wu, Eun-Suk Seo, T. S. Dai, S. Xu, Dawei Zhao, Federico Cindolo, Z.R. Dong, V. Shoutko, Joachim Trümper, Maria Ionica, Guohuai Zhu, V. Commichau, Z.P. Zhang, E. Shoumilov, E. Riihonen, A. Mihul, G.P. Barreira, M. J. Boschini, M. Ribordy, Tengfei Song, H. Anderhub, M. Duranti, U. Roeser, T. Siedenburg, H.F. Chen, M. Steuer, C. Delgado, Mao-Zhi Yang, Zhenghao Xu, A. Lebedev, Dong-Chul Son, H. Suter, G.S. Sun, A. Bartoloni, V. Koutsenko, Eino Valtonen, W. Wallraff, P.C. Xia, F. Spada, P. Saouter, J. Favier, Z. L. Ren, Waclaw Karpinski, X. D. Cai, Changgen Yang, I. Vetlitsky, W.H. Park, E. Cortina-Gil, G. Bruni, F. Palmonari, A. Pevsner, D. Vité, M. Buénerd, Tzihong Chiueh, S. R. Ro, S. Natale, G. Laurenti, S. Waldmeier Wicki, E. P. Velikhov, B. Zimmermann, R. Becker, Y. Galaktionov, Roald Z. Sagdeev, Ciaran Williams, Merja Tornikoski, J.L. Yan, Markus Cristinziani, J. J. Torsti, Antonino Zichichi, L. Bellagamba, K.S. Kim, A. Arefiev, F. Barao, R. R. McNeil, Jing Wang, G. Sartorelli, Nicola Tomassetti, P. Cannarsa, Y. H. Chang, T. Eronen, G. Kenney, M. Aguilar, Felicitas Pauss, V. Hermel, Werner Lustermann, Behcet Alpat, M. Basile, Z.G. Chen, G. Flügge, G. N. Kim, F. Spinella, M. Bourquin, H. L. Zhuang, J. Yang, You Zhou, Nicolas Produit, D. Luckey, F. Vezzu, G. Lu, C. Maña, C.H. Lin, Samuel C.C. Ting, Fabrizio Giulio Luca Pilo, G. Castellini, J. Vandenhirtz, D. Casadei, G. Laborie, P. Giusti, S. Di Falco, O. Grimm, Paolo Zuccon, A. Hasan, Mauro Menichelli, F. Giovacchini, G. Schwering, Daijin Kim, W.Q. Gu, F. Zhou, N. Fouque, I. Cernuda, E. Fiandrini, H. S. Chen, D. Santos, S. Urpo, G. Viertel, Luísa Arruda, G. Lamanna, K. Hangarter, Lucio Quadrani, B. Verlaat, P. Berges, Ari Mujunen, K. Wiik, J. Berdugo, G. Boella, N.A. Chernoplekov, Anselmo Margotti, W. Hungerford, Timo Laitinen, M. Pauluzzi, D. Ren, Giuseppe Levi, Lu Yuzhang, LinLi Yan, A.I. Oliva, V. Pojidaev, C. Lechanoine-Leluc, S.W. Ye, Roberto Battiston, Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Annecy de Physique des Particules (LAPP), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), AMS, AGUILAR M., ALCARAZ J., ALLABY J., ALPAT B., AMBROSI G., ANDERHUB H., AO L., AREFIEV A., ARRUDA L., AZZARELLO P., BASILE M., BARAO F., BARREIRA G., BARTOLONI A., BATTISTON R., BECKER R., BECKER U., BELLAGAMBA L., BERDUGO J., BERGES P., BERTUCCI B., BILAND A., BINDI V., BOELLA G., BOSCHINI M., BOURQUIN M., BRUNI G., BUENERD M., BURGER JD., BURGER WJ., CAI XD., CANNARSA P., CAPELL M., CASADEI D., CASAUS J., CASTELLINI G., CERNUDA I., CHANG YH., CHEN HF., CHEN HS., CHEN ZG., CHERNOPLEKOV NA., CHIUEH TH., CHOI YY., CINDOLO F., COMMICHAU V., CONTIN A., CORTINA-GIL E., CRESPO D., CRISTINZIANI M., DAI TS., DELA GUIA C., DELGADO C., DI FALCO S., DJAMBAZOV L., D'ANTONE I., DONG ZR., DURANTI M., ENGELBERG J., EPPLING FJ., ERONEN T., EXTERMANN P., FAVIER J., FIANDRINI E., FISHER PH., FLUGGE G., FOUQUE N., GALAKTIONOV Y., GERVASI M., GIOVACCHINI F., GIUSTI P., GRANDI D., GRIMM O., GU WQ., HAINO S., HANGARTER K., HASAN A., HERMEL V., HOFER H., HUNGERFORD W., IONICA M., JONGMANNS M., KARLAMAA K., KARPINSKI W., KENNEY G., KIM DH., KIM GN., KIM KS., KIRN T., KLIMENTOV A., KOSSAKOWSKI R., KOUNINE A., KOUTSENKO V., KRAEBER M., LABORIE G., LAITINEN T., LAMANNA G., LAURENTI G., LEBEDEV A., LECHANOINE-LELUC C., LEE MW., LEE SC., LEVI G., LIN CH., LIU HT., LU G., LU YS., LUBELSMEYER K., LUCKEY D., LUSTERMANN W., MANA C., MARGOTTI A., MAYET F., MCNEIL RR., MENICHELLI M., MIHUL A., MUJUNEN A., NATALE S., OLIVA A., PALMONARI F., PANICCIA M., PARK HB., PARK WH., PAULUZZI M., PAUSS F., PEREIRA R., PERRIN E., PEVSNER A., PILO F., PIMENTA M., PLYASKIN V., POJIDAEV V., POHL M., PRODUIT N., QUADRANI L., RANCOITA PG., RAPIN D., REN D., REN Z., RIBORDY M., RIIHONEN E., RITAKARI J., RO S., ROESER U., SAGDEEV R., SANTOS D., SARTORELLI G., SAOUTER P., SBARRA C., SCHAEL S., VON DRATZIG AS., SCHWERING G., SEO ES., SHIN JW., SHOUMILOV E., SHOUTKO V., SIEDENBURG T., SIEDLING R., SON D., SONG T., SPADA FR., SPINELLA F., STEUER M., SUN GS., SUTER H., TANG XW., TING SCC., TING SM., TOMASSETTI N., TORNIKOSKI M., TORSTI J., TRUMPER J., ULBRICHT J., URPO S., VALTONEN E., VANDENHIRTZ J., VELIKHOV E., VERLAAT B., VETLITSKY I., VEZZU F., VIALLE JP., VIERTEL G., VITE D., VON GUNTEN H., WICKI SW., WALLRAFF W., WANG JZ., WIIK K., WILLIAMS C., WU SX., XIA PC., XU S., XU ZZ., YAN JL., YAN LG., YANG CG., YANG J., YANG M., YE SW., ZHANG HY., ZHANG ZP., ZHAO DX., ZHOU F., ZHOU Y., ZHU GY., ZHU WZ., ZHUANG HL., ZICHICHI A., ZIMMERMANN B., ZUCCON P, Aguilar, M, Alcaraz, J, Allaby, J, Alpat, B, Ambrosi, G, Anderhub, H, Ao, L, Arefiev, A, Arruda, L, Azzarello, P, Basile, M, Barao, F, Barreira, G, Bartoloni, A, Battiston, R, Becker, R, Becker, U, Bellagamba, L, Berdugo, J, Berges, P, Bertucci, B, Biland, A, Bindi, V, Boella, G, Boschini, M, Bourquin, M, Bruni, G, Buénerd, M, Burger, J, Burger, W, Cai, X, Cannarsa, P, Capell, M, Casadei, D, Casaus, J, Castellini, G, Cernuda, I, Chang, Y, Chen, H, Chen, Z, Chernoplekov, N, Chiueh, T, Choi, Y, Cindolo, F, Commichau, V, Contin, A, Cortina Gil, E, Crespo, D, Cristinziani, M, Dai, T, dela Guia, C, Delgado, C, Di Falco, S, Djambazov, L, D’Antone, I, Dong, Z, Duranti, M, Engelberg, J, Eppling, F, Eronen, T, Extermann, P, Favier, J, Fiandrini, E, Fisher, P, Flügge, G, Fouque, N, Galaktionov, Y, Gervasi, M, Giovacchini, F, Giusti, P, Grandi, D, Grimm, O, Gu, W, Haino, S, Hangarter, K, Hasan, A, Hermel, V, Hofer, H, Hungerford, W, Ionica, M, Jongmanns, M, Karlamaa, K, Karpinski, W, Kenney, G, Kim, D, Kim, G, Kim, K, Kirn, T, Klimentov, A, Kossakowski, R, Kounine, A, Koutsenko, V, Kraeber, M, Laborie, G, Laitinen, T, Lamanna, G, Laurenti, G, Lebedev, A, Lechanoine Leluc, C, Lee, M, Lee, S, Levi, G, Lin, C, Liu, H, Lu, G, Lu, Y, Lübelsmeyer, K, Luckey, D, Lustermann, W, Maña, C, Margotti, A, Mayet, F, Mcneil, R, Menichelli, M, Mihul, A, Mujunen, A, Natale, S, Oliva, A, Palmonari, F, Paniccia, M, Park, H, Park, W, Pauluzzi, M, Pauss, F, Pereira, R, Perrin, E, Pevsner, A, Pilo, F, Pimenta, M, Plyaskin, V, Pojidaev, V, Pohl, M, Produit, N, Quadrani, L, Rancoita, P, Rapin, D, Ren, D, Ren, Z, Ribordy, M, Riihonen, E, Ritakari, J, Ro, S, Roeser, U, Sagdeev, R, Santos, D, Sartorelli, G, Saouter, P, Sbarra, C, Schael, S, von Dratzig, A, Schwering, G, Seo, E, Shin, J, Shoumilov, E, Shoutko, V, Siedenburg, T, Siedling, R, Son, D, Song, T, Spada, F, Spinella, F, Steuer, M, Sun, G, Suter, H, Tang, X, Ting, S, Tomassetti, N, Tornikoski, M, Torsti, J, Trümper, J, Ulbricht, J, Urpo, S, Valtonen, E, Vandenhirtz, J, Velikhov, E, Verlaat, B, Vetlitsky, I, Vezzu, F, Vialle, J, Viertel, G, Vité, D, Von Gunten, H, Wicki, S, Wallraff, W, Wang, J, Wiik, K, Williams, C, Wu, S, Xia, P, Xu, S, Xu, Z, Yan, J, Yan, L, Yang, C, Yang, J, Yang, M, Ye, S, Zhang, H, Zhang, Z, Zhao, D, Zhou, F, Zhou, Y, Zhu, G, Zhu, W, Zhuang, H, Zichichi, A, Zimmermann, B, Zuccon, P, Massachusetts Institute of Technology. Department of Physics, Massachusetts Institute of Technology. Laboratory for Nuclear Science, Becker, R., Becker, Ulrich J., Berges, P., Burger, Joseph D., Cai, Xudong, Capell, Michael H., Dai, T. S., Eppling, Frederic J., Fisher, Peter H., Klimentov, A., Kounine, Andrei, Koutsenko, Vladimir, Lebedev, Alexei, Luckey, P. David, Jr., Shoutko, V., Siedenburg, T., Steuer, M., Ting, Samuel C. C., Wu. S. X., Xu, S., and Zhou, F.
Subjects: Nuclear reaction, Astrophysics and Astronomy, [PHYS.ASTR.HE]Physics [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], genetic structures, Cosmic ray, Isotopes of boron, 01 natural sciences, High Energy Physics - Experiment, Nuclear physics, ACCELERATION OF PARTICLES, ABUNDANCES, Nucleosynthesis, 0103 physical sciences, Alpha Magnetic Spectrometer, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], acceleration of particles, cosmic rays, nuclear reactions, nucleosynthesis, abundances, 010303 astronomy & astrophysics, Cosmic ray spallation, Physics, NUCLEAR REACTIONS, NUCLEOSYNTHESIS, 010308 nuclear & particles physics, [SDU.ASTR.HE]Sciences of the Universe [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Astronomy and Astrophysics, COSMIC RAYS, FIS/01 - FISICA SPERIMENTALE, Space and Planetary Science, Isotopes of beryllium, Astrophysics - High Energy Astrophysical Phenomena, Heliosphere
Abstract: The variety of isotopes in cosmic rays allows us to study different aspects of the processes that cosmic rays undergo between the time they are produced and the time of their arrival in the heliosphere. In this paper, we present measurements of the isotopic ratios [superscript 2]H/[superscript 4]He, [superscript 3]He/[superscript 4]He, [superscript 6]Li/[superscript 7]Li, [superscript 7]Be/([superscript 9]Be+[superscript 10]Be), and [superscript 10]B/[superscript 11]B in the range 0.2-1.4 GeV of kinetic energy per nucleon. The measurements are based on the data collected by the Alpha Magnetic Spectrometer, AMS-01, during the STS-91 flight in 1998 June., United States. Dept. of Energy, Massachusetts Institute of Technology
Published: 2011
Full Text: View/download PDF

41. Higgs + 2 jets: Compact Analytic Results

Author: Ciaran Williams
Subjects: Physics, Quantum chromodynamics, Top quark, Particle physics, Unitarity, High Energy Physics::Lattice, Hadron, Scalar (mathematics), High Energy Physics::Phenomenology, FOS: Physical sciences, Gluon, symbols.namesake, High Energy Physics - Phenomenology, High Energy Physics - Phenomenology (hep-ph), symbols, Higgs boson, Feynman diagram, High Energy Physics::Experiment
Abstract: This report describes the recent efforts to compute analytic formulae for the Next-to-Leading-Order (NLO) QCD corrections to Higgs plus two jet production at hadron colliders. In these calculations the Higgs boson couples to gluons via a top-quark loop which is integrated out to form an effective vertex. The amplitudes are further simplified by splitting the real Higgs scalar into the sum of two complex scalars phi and phi^dagger. Four-dimensional unitarity is used to construct the cut-containing pieces of the amplitude, while a variety of bootstrap and Feynman diagram techniques are used to construct the rational pieces. The results described here are valid in the limit of a large top quark mass and when the transverse momenta of the jets are less than mt., Comment: Talk given at RADCOR 2009 - 9th International Symposium on Radiative Corrections (Applications of Quantum Field Theory to Phenomenology) October 25 - 30 2009. 6 pages
Published: 2010
Full Text: View/download PDF

42. One-loop Higgs plus four gluon amplitudes: full analytic results

Author: Simon Badger, Pierpaolo Mastrolia, E.W. Nigel Glover, and Ciaran Williams
Subjects: Physics, Nuclear and High Energy Physics, Top quark, Particle physics, Field (physics), Unitarity, High Energy Physics::Lattice, High Energy Physics::Phenomenology, FOS: Physical sciences, Jet (particle physics), Helicity, Gluon, High Energy Physics - Phenomenology, symbols.namesake, High Energy Physics - Phenomenology (hep-ph), symbols, Higgs boson, Feynman diagram, ddc:530, High Energy Physics::Experiment, Particle Physics - Phenomenology
Abstract: We consider one-loop amplitudes of a Higgs boson coupled to gluons in the limit of a large top quark mass. We treat the Higgs as the real part of a complex field phi that couples to the self-dual field strengths and compute the one-loop corrections to the phi-NMHV amplitude, which contains one gluon of positive helicity whilst the remaining three have negative helicity. We use four-dimensional unitarity to construct the cut-containing contributions and a hybrid of Feynman diagram and recursive based techniques to determine the rational piece. Knowledge of the phi-NMHV contribution completes the analytic calculation of the Higgs plus four gluon amplitude. For completeness we also include expressions for the remaining helicity configurations which have been calculated elsewhere. These amplitudes are relevant for Higgs plus jet production via gluon fusion in the limit where the top quark is large compared to all other scales in the problem., 24 pages, 4 figures, JHEP3 class, typos fixed
Published: 2010
Full Text: View/download PDF

43. Hadronic production of a Higgs boson and two jets at next-to-leading order

Author: Ciaran Williams, John M. Campbell, and R. Keith Ellis
Subjects: Quantum chromodynamics, Physics, Nuclear and High Energy Physics, Particle physics, Large Hadron Collider, Hadron, High Energy Physics::Phenomenology, Tevatron, FOS: Physical sciences, Elementary particle, High Energy Physics - Phenomenology, Amplitude, High Energy Physics - Phenomenology (hep-ph), Higgs boson, High Energy Physics::Experiment, Boson
Abstract: We perform an update of the next-to-leading order calculation of the rate for Higgs boson production in association with two jets. Our new calculation incorporates the full analytic result for the one-loop virtual amplitude. This new theoretical information allows us to construct a code including the decay of the Higgs boson without incurring a prohibitive penalty in computer running time. Results are presented for the Tevatron, where implications for the Higgs search are sketched, and also for a range of scenarios at the LHC., Comment: 16 pages, 4 figures
Published: 2010
Full Text: View/download PDF

44. Analytic results for the one-loop NMHV $H\bar{q}qgg$ amplitude

Author: John M. Campbell, Ciaran Williams, Simon Badger, and R. Keith Ellis
Subjects: Physics, Nuclear and High Energy Physics, Top quark, Particle physics, High Energy Physics::Lattice, High Energy Physics::Phenomenology, FOS: Physical sciences, Parton, Helicity, Gluon, Loop (topology), High Energy Physics - Phenomenology, Amplitude, High Energy Physics - Phenomenology (hep-ph), Higgs boson, High Energy Physics::Experiment, ddc:530, Limit (mathematics)
Abstract: We compute the one-loop amplitude for a Higgs boson, a quark-antiquark pair and a pair of gluons of negative helicity, i.e. for the next-to-maximally helicity violating (NMHV) case, A(H, qbar-, q+, g-, g-). The calculation is performed using an effective Lagrangian which is valid in the limit of very large top quark mass. As a result of this paper all amplitudes for the transition of a Higgs boson into 4 partons are now known analytically at one-loop order., Comment: 21 pages, 1 figure
Published: 2009
Full Text: View/download PDF

45. MHV amplitudes in N=2 SQCD and in N=4 SYM at one loop

Author: Ciaran Williams, Valentin V. Khoze, and E.W. Nigel Glover
Subjects: Quantum chromodynamics, Physics, High Energy Physics - Theory, Nuclear and High Energy Physics, Particle physics, Unitarity, High Energy Physics::Lattice, High Energy Physics::Phenomenology, Adjoint representation, Vertex function, FOS: Physical sciences, Helicity, High Energy Physics - Phenomenology, High Energy Physics - Phenomenology (hep-ph), High Energy Physics - Theory (hep-th), Supersymmetric gauge theory, MHV amplitudes, Gauge theory
Abstract: Using four-dimensional unitarity and MHV-rules we calculate the one-loop MHV amplitudes with all external particles in the adjoint representation for N=2 supersymmetric QCD with N_f fundamental flavours. We start by considering such amplitudes in the superconformal N=4 gauge theory where the N=4 supersymmetric Ward identities (SWI) guarantee that all MHV amplitudes for all types of external particles are given by the corresponding tree-level result times a universal helicity- and particle-type-independent contribution. In N=2 SQCD the MHV amplitudes differ from those for N=4 for general values of N_f and N_c. However, for N_f=2N_c where the N=2 SQCD is conformal, the N=2 MHV amplitudes (with all external particles in the adjoint representation) are identical to the N=4results. This factorisation at one-loop motivates us to pose a question if there may be a BDS-like factorisation for these amplitudes which also holds at higher orders of perturbation theory in superconformal N=2 theory., Comment: In v2 we consider only MHV amplitudes with all external particles in the adjoint representation. References added. 17 pages, 3 figures
Published: 2008
Full Text: View/download PDF

46. The Alpha Magnetic Spectrometer (AMS) on the International Space Station: Part I – results from the test flight on the space shuttle

Author: P. Extermann, H. Hofer, J.P. Richeux, Jose Maria Kenny, M. Jongmanns, H. Anderhub, P. Giusti, A. Hasan, Mauro Menichelli, G. Scolieri, Y.S. Lu, I. Lopes, S. Ro, G. Schwering, Eun-Suk Seo, L. Baldini, E. Lanciotti, F. Vezzu, Maria Ionica, S.W. Ye, V. Koutsenko, Eino Valtonen, M.Y. Kim, G. Sartorelli, D. Rapin, V. Plyaskin, Werner Lustermann, Behcet Alpat, W.Q. Gu, W.Z. Zhu, C. Delgado, E. Fiandrini, Yu. Galaktionov, D.H. Kim, J. Alcaraz, S. X. Wu, W.H. Park, Felicitas Pauss, B. Verlaat, P. Berges, K. Karlamaa, S.C.C. Ting, F. Palmonari, Zhenghao Xu, Zhuoxiang Ren, F. Velcea, Tzihong Chiueh, G. Barbier, H.B. Park, R. Kossakowski, A. Klimentov, S. Urpo, Ari Mujunen, A. Lebedev, Dong-Chul Son, G. Laurenti, K. Luebelsmeyer, E. Shoumilov, W. Hungerford, H. S. Chen, N. Produit, M. Buenerd, S. Waldmeier Wicki, M. Basile, E. Riihonen, A. Mihul, Timo Laitinen, J. Yang, V. Postolache, V. Pojidaev, M. Steuer, P.C. Xia, G.S. Sun, Jian Wang, M. Ribordy, K. Hangarter, H. L. Zhuang, M. Pauluzzi, Stefan Schael, H. Suter, Guohuai Zhu, G. Boella, X.W. Tang, M. Kraber, A. Pevsner, M. A. Huang, Mao-Zhi Yang, Tao Song, J.L. Yan, N.A. Chernoplekov, J. Vandenhirtz, Z.G. Chen, C. Camps, Ciaran Williams, D. Ren, D. Luckey, I. Vetlitsky, Samuel C.C. Ting, N. Dinu, Zhidong Zhang, Anselmo Margotti, E. Cortina-Gil, M. Bourquin, A. Papi, Adrian Biland, R. Ionica, L. Djambazov, Paolo Zuccon, A. Contin, I. D'Antone, M.W. Lee, Jungwook Shin, F. Barao, G. Castellini, J. P. Da Cunha, Gui Nyun Kim, N. Fouque, P. Levtchenko, Massimo Gervasi, Kyung-Suk Cho, J. D. Burger, F. Mayet, M. Pohl, P. Yeh, G. Lu, C. Maña, C. Lechanoine-Leluc, A. Schultz von Dratzig, C. Rossin, Hengchang Liu, A. Mourao, S. Blasko, G. Laborie, C. Sbarra, Peter H. Fisher, L.G. Yan, V. Hermel, J.D. Deus, X. D. Cai, M.J. Choi, O. Grimm, J. Casaus, M. Capell, Philipp Azzarello, R. Siedling, J. Berdugo, Yun Wang, A. Arefiev, Roald Z. Sagdeev, J. Engelberg, H. von Gunten, C.L. Liu, L. Bellagamba, Changgen Yang, D. Casadei, U. Roser, R. R. McNeil, B. Meillon, Giuseppe Levi, Y.L. Chuang, K. Wiik, P. Bene, Federico Cindolo, J. J. Torsti, Antonino Zichichi, L. Brocco, J. Ritakari, Y. H. Chang, G. Kenney, P. Cannarsa, Y.Y. Choi, D. Barancourt, J. Favier, Waclaw Karpinski, E. Babucci, U. Becker, Dawei Zhao, R. Becker, Z.R. Dong, E. Perrin, K.S. Kim, Claudia Cecchi, F. J. Eppling, M. Aguilar, V. Shoutko, S. Bizzaglia, G. Esposito, M. Pimenta, G. Fluegge, D. Grandi, B. Bertucci, D. Santos, G. Ambrosi, T. S. Dai, A. Pesci, B.C. Wang, D. Vité, G. Lamanna, G. Viertel, J. P. Vialle, H.F. Chen, G.P. Barreira, W. J. Burger, Frank Raupach, Roberto Battiston, L. Ao, J. Ulbricht, Hao Zhang, S.C. Lee, J. Trümper, P. Emonet, M. J. Boschini, V. Commichau, E. P. Velikhov, B. Zimmermann, Merja Tornikoski, Markus Cristinziani, T. Eronen, P. G. Rancoita, W. Wallraff, G. Bruni, Aguilar, M, Alcaraz, J, Allaby, J, Alpat, B, Ambrosi, G, Anderhub, H, Ao, L, Arefiev, A, Azzarello, P, Babucci, E, Baldini, L, Basile, M, Berdugo, J, Berges, P, Bertucci, B, Biland, A, Bizzaglia, S, Blasko, S, Boella, G, Boschini, M, Bourquin, M, Brocco, L, Bruni, G, Buenerd, M, Burger, J, Burger, W, Cai, X, Camps, C, Cannarsa, P, Capell, M, Casadei, D, Casaus, J, Castellini, G, Cecchi, C, Chang, Y, Chen, H, Chen, Z, Chernoplekov, N, Chiueh, T, Cho, K, Choi, M, Choi, Y, Chuang, Y, Cindolo, F, Commichau, V, Contin, A, Cortina-Gil, E, Cristinziani, M, da Cunha, J, Dai, T, Delgado, C, Deus, J, Dinu, N, Djambazov, L, D'Antone, I, Dong, Z, Emonet, P, Engelberg, J, Eppling, F, Eronen, T, Esposito, G, Extermann, P, Favier, J, Fiandrini, E, Fisher, P, Fluegge, G, Fouque, N, Galaktionov, Y, Gervasi, M, Giusti, P, Grandi, D, Grimms, O, Gu, W, Hangarter, K, Hasan, A, Hermel, V, Hofer, H, Huang, M, Hungerford, W, Ionica, M, Ionica, R, Jongmanns, M, Karlamaa, K, Karpinski, W, Kenney, G, Kenny, J, Kim, D, Kim, G, Kim, K, Kim, M, Klimentov, A, Kossakowski, R, Koutsenko, V, Kraeber, M, Laborie, G, Laitinen, T, Lamanna, G, Lanciotti, E, Laurenti, G, Lebedev, A, Lechanoine-Leluc, C, Lee, M, Lee, S, Levi, G, Levtchenko, P, Liu, C, Liu, H, Lopes, I, Lu, G, Lu, Y, Lubelsmeyer, K, Luckey, D, Lustermann, W, Mana, C, Margotti, A, Mayet, F, Mcneil, R, Meillon, B, Menichelli, M, Mihul, A, Mourao, A, Mujunen, A, Palmonari, F, Papi, A, Park, H, Park, W, Pauluzzi, M, Pauss, F, Perrin, E, Pesci, A, Pevsner, A, Pimenta, M, Plyaskin, V, Pojidaev, V, Pohl, M, Postolache, V, Produit, N, Rancoita, P, Rapin, D, Raupach, F, Ren, D, Ren, Z, Ribordy, M, Richeux, J, Riihonen, E, Ritakari, J, Ro, S, Roeser, U, Rossin, C, Sagdeev, R, Santos, D, Sartorelli, G, Sbarra, C, Schael, S, von Dratzig, A, Schwering, G, Scolieri, G, Seo, E, Shin, J, Shoutko, V, Shoumilov, E, Siedling, R, Son, D, Song, T, Steuer, M, Sun, G, Suter, H, Tang, X, Ting, S, Tornikoski, M, Torsti, J, Trumper, J, Ulbricht, J, Urpo, S, Valtonen, E, Vandenhirtz, J, Velcea, F, Velikhov, E, Verlaat, B, Vetlitsky, I, Vezzu, F, V, Jp, Viertel, G, Vite, D, Von Gunten, H, Wicki, S, Wallraff, W, Wang, B, Wang, J, Wang, Y, Wiik, K, Williams, C, Wu, S, Xia, P, Yan, J, Yan, L, Yang, C, Yang, J, Yang, M, Ye, S, Yeh, P, Xu, Z, Zhang, H, Zhang, Z, Zhao, D, Zhu, G, Zhu, W, Zhuang, H, Zichichi, A, Zimmermann, B, Zuccon, P, Ambrosi, Giovanni, Azzarello, Philipp, Bene, Pierre, Bourquin, Maurice, Cortina Gil, Eduardo, Cristinziani, Markus, Emonet, Pascal Philippe, Extermann, Pierre, Leluc, Catherine, Perrin, Eric, Pohl, Martin, Produit, Nicolas, Rapin, Divic Jean, Ribordy, Mathieu, Richeux, Jean-Pierre, Vite, Davide, Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Annecy de Physique des Particules (LAPP), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), AMS, Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas, CIEMAT, E-28040, Madrid, Spain, and UCL - SST/IRMP - Institut de recherche en mathématique et physique
Subjects: Physics, 010308 nuclear & particles physics, FIS/06 - FISICA PER IL SISTEMA TERRA E PER IL MEZZO CIRCUMTERRESTRE, General Physics and Astronomy, chemistry.chemical_element, Electron, ddc:500.2, 01 natural sciences, Spectral line, [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], Nuclear physics, FIS/05 - ASTRONOMIA E ASTROFISICA, Positron, Earth's magnetic field, FIS/01 - FISICA SPERIMENTALE, chemistry, 13. Climate action, Antiproton, 0103 physical sciences, Alpha Magnetic Spectrometer, Nucleon, 010303 astronomy & astrophysics, AMS, Cosmic Rays, Antimatter, Helium, FIS/04 - FISICA NUCLEARE E SUBNUCLEARE
Abstract: The Alpha Magnetic Spectrometer (AMS) was flown on the space shuttle Discovery during flight STS-91 (June 1998) in a 51.7 deg orbit at altitudes between 320 and 390 km. A search for antihelium nuclei in the rigidity range 1–140 GV was performed. No antihelium nuclei were detected at any rigidity. An upper limit on the flux ratio of antihelium to helium of < 1.1×10^−6 was obtained. The high energy proton, electron, positron, helium, antiproton and deuterium spectra were accurately measured. For each particle and nuclei two distinct spectra were observed: a higher energy spectrum and a substantial second spectrum. Positrons in the second spectrum were found to be much more abundant than electrons. Tracing particles from the second spectra shows that most of them travel for an extended period of time in the geomagnetic field, and that the positive particles (p and e+) and negative ones (e−) originate from two complementary geographic regions. The second helium spectrum flux over the energy range 0.1–1.2 GeV/nucleon was measured to be (6.3 ± 0.9) × 10^−3(m^2 s sr)^−1. Over 90 percent of the helium flux was determined to be 3He at the 90% confidence level
Published: 2002
Full Text: View/download PDF

47. Search for antihelium in cosmic rays

Author: Z.R. Dong, S. Bizzaglia, G. Ambrosi, J. Casaus, M. Pimenta, T. S. Dai, Samuel C.C. Ting, L. Djambazov, B.C. Wang, G. Molinari, A. Klimentov, B. Bertucci, S. X. Wu, R. Pilastrini, G. Lamanna, L.G. Yan, R. Siedling, J. Favier, Philipp Azzarello, J. J. Torsti, Antonino Zichichi, A. Hasan, Mauro Menichelli, L. Ao, Inkyu Park, J.P. Vialle, M. Steuer, P.C. Xia, Peter H. Fisher, Ilya Usoskin, P. G. Rancoita, Jing Wang, F. Palmonari, J. Isbert, M. Ribordy, G. Boella, H. von Gunten, P. Crespo, W. J. Burger, N. Fouque, R. Ionica, Federico Cindolo, J.P. Richeux, R. Cavalletti, D.X. Zhao, U. Roeser, N.A. Chernoplekov, C. G. Yang, Nicolas Produit, M. Buenerd, A. Cotta-Ramusino, R. Flaminio, J. P. Da Cunha, Anselmo Margotti, D. Rapin, V. Plyaskin, W. Kim, Roberto Battiston, G.Y. Zhu, W.Z. Zhu, G. Fluegge, G. Bruni, G. Viertel, P. Levtchenko, E. Fiandrini, G. Laurenti, K. Luebelsmeyer, S. Waldmeier Wicki, S.C. Lee, Yu. Galaktionov, F. Massera, D. Vité, J. Ulbricht, A. Chiarini, Hao Zhang, H. S. Chen, C. Rossin, G. Pancaldi, Felicitas Pauss, S. Recupero, Ciaran Williams, R. Kossakowski, W. Karpinski, J. Alcaraz, F. Barao, P. Yeh, E. Emonet, L.K. Ding, H.T. Liu, E. P. Velikhov, G. Torromeo, M. Basile, G.S. Sun, A. Pevsner, J.L. Yan, X. D. Cai, L. Baldini, F. Mezzanotte, C.L. Liu, L. Bellagamba, S. Blasko, K. Hangarter, J. Berdugo, Adrian Biland, G. Barbier, J. Vandenhirtz, V. Hermel, A. Arefiev, E. Prati, Jose Maria Kenny, R. R. McNeil, T.G. Guzik, B. Meillon, W.K. Gu, G. Kenney, I. D'Antone, J.P. Wefel, Markus Cristinziani, T. Eronen, R. Becker, Y.L. Chuang, P. Bene, B. Alpat, D. Luckey, E. Riihonen, A. Mihul, M. Jongmanns, C.C. Feng, D. Casadei, W. Wallraff, J. Krieger, H.L. Zhuang, G. Castellini, Massimo Gervasi, Zhuoxiang Ren, G. Schwering, W. Hungerford, A. Papi, Timo Laitinen, D. Santos, F. Tenbusch, B. Verlaat, P. Berges, Raffaele Mezzenga, S. Urpo, Ari Mujunen, G. Laborie, V. Shoutko, M. Pauluzzi, Y. S. Lu, G.P. Barreira, Yun Wang, V. Commichau, J. Truemper, A. Pesci, D. Ren, M. Capell, V. Koutsenko, Eino Valtonen, F. Vezzu, P. Cannarsa, C. Camps, T.P. Li, M. Ionica, H. Postema, A. Contin, M. Yang, E. Babucci, U. Becker, A. Lebedev, Dong-Chul Son, P. Giusti, I. Lopes, E. Perrin, F. J. Eppling, D. Alvisi, G. Lu, F. Raupach, C. Maña, P. Extermann, S. M. Ting, H. Hofer, G. Esposito, I. Vetlitsky, G. Sartorelli, M. Lolli, G. Maehlum, E.A. Werner, Fabio Finelli, Z.G. Chen, Werner Lustermann, Giuseppe Levi, X. W. Tang, Tao Song, M. Bourquin, V. Pojidaev, E. Shoumilov, H. Suter, J. D. Burger, Roald Z. Sagdeev, A. Mourao, J. Ritakari, Y. H. Chang, D. Barancourt, N. Dinu, H. Anderhub, Tzihong Chiueh, M. A. Huang, Jorge Dias de Deus, F. Mayet, A. Schultz von Dratzig, Alcaraz, J, Alvisi, D, Alpat, B, Ambrosi, G, Anderhub, H, Ao, L, Arefiev, A, Azzarello, P, Babucci, E, Baldini, L, Basile, M, Barancourt, D, Barao, F, Barbier, G, Barreira, G, Battiston, R, Becker, R, Becker, U, Bellagamba, L, Béné, P, Berdugo, J, Berges, P, Bertucci, B, Biland, A, Bizzaglia, S, Blasko, S, Boella, G, Bourquin, M, Bruni, G, Buenerd, M, Burger, J, Burger, W, Cai, X, Cavalletti, R, Camps, C, Cannarsa, P, Capell, M, Casadei, D, Casaus, J, Castellini, G, Chang, Y, Chen, H, Chen, Z, Chernoplekov, N, Chiarini, A, Chiueh, T, Chuang, Y, Cindolo, F, Commichau, V, Contin, A, Cotta Ramusino, A, Crespo, P, Cristinziani, M, Dacunha, J, Dai, T, Deus, J, Ding, L, Dinu, N, Djambazov, L, D'Antone, I, Dong, Z, Emonet, P, Eppling, F, Eronen, T, Esposito, G, Extermann, P, Favier, J, Feng, C, Fiandrini, E, Finelli, F, Fisher, P, Flaminio, R, Fluegge, G, Fouque, N, Galaktionov, Y, Gervasi, M, Giusti, P, Gu, W, Guzik, T, Hangarter, K, Hasan, A, Hermel, V, Hofer, H, Huang, M, Hungerford, W, Ionica, M, Ionica, R, Isbert, J, Jongmanns, M, Karpinski, W, Kenney, G, Kenny, J, Kim, W, Klimentov, A, Krieger, J, Kossakowski, R, Koutsenko, V, Laborie, G, Laitinen, T, Lamanna, G, Laurenti, G, Lebedev, A, Lee, S, Levi, G, Levtchenko, P, Li, T, Liu, C, Liu, H, Lolli, M, Lopes, I, Lu, G, Lu, Y, Lübelsmeyer, K, Luckey, D, Lustermann, W, Maehlum, G, Maña, C, Margotti, A, Massera, F, Mayet, F, Mcneil, R, Meillon, B, Menichelli, M, Mezzanotte, F, Mezzenga, R, Mihul, A, Molinari, G, Mourao, A, Mujunen, A, Palmonari, F, Pancaldi, G, Papi, A, Park, I, Pauluzzi, M, Pauss, F, Perrin, E, Pesci, A, Pevsner, A, Pilastrini, R, Pimenta, M, Plyaskin, V, Pojidaev, V, Postema, H, Prati, E, Produit, N, Rancoita, P, Rapin, D, Raupach, F, Recupero, S, Ren, D, Ren, Z, Ribordy, M, Richeux, J, Riihonen, E, Ritakari, J, Roeser, U, Roissin, C, Sagdeev, R, Santos, D, Sartorelli, G, Schultzvondratzig, A, Schwering, G, Shoutko, V, Shoumilov, E, Siedling, R, Son, D, Song, T, Steuer, M, Sun, G, Suter, H, Tang, X, Ting, S, Tenbusch, F, Torromeo, G, Torsti, J, Trümper, J, Ulbricht, J, Urpo, S, Usoskin, I, Valtonen, E, Vandenhirtz, J, Velikhov, E, Verlaat, B, Vetlitsky, I, Vezzu, F, Vialle, J, Viertel, G, Vité, D, Vongunten, H, Waldmeierwicki, S, Wallraff, W, Wang, B, Wang, J, Wang, Y, Wefel, J, Werner, E, Williams, C, Wu, S, Xia, P, Yan, J, Yan, L, Yang, C, Yang, M, Yeh, P, Zhang, H, Zhao, D, Zhu, G, Zhu, W, Zhuang, H, Zichichi, A, Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Annecy de Physique des Particules (LAPP), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), and AMS
Subjects: Astrophysics and Astronomy, Nuclear and High Energy Physics, FOS: Physical sciences, chemistry.chemical_element, Space Shuttle, Cosmic ray, Astrophysics, 7. Clean energy, 01 natural sciences, High Energy Physics - Experiment, [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], High Energy Physics - Experiment (hep-ex), FIS/05 - ASTRONOMIA E ASTROFISICA, Rigidity (electromagnetism), 0103 physical sciences, Alpha Magnetic Spectrometer, 010306 general physics, Helium, Physics, 010308 nuclear & particles physics, Astrophysics (astro-ph), Astronomy, Flux ratio, FIS/01 - FISICA SPERIMENTALE, chemistry, Cosmic rays: anti-helium, FIS/04 - FISICA NUCLEARE E SUBNUCLEARE
Abstract: The Alpha Magnetic Spectrometer (AMS) was flown on the space shuttle Discovery during flight STS-91 in a 51.7 degree orbit at altitudes between 320 and 390 km. A total of 2.86 * 10^6 helium nuclei were observed in the rigidity range 1 to 140 GV. No antihelium nuclei were detected at any rigidity. An upper limit on the flux ratio of antihelium to helium of < 1.1 * 10^-6 is obtained., 18 pages, Latex, 9 .eps figures
Published: 2000

48. Leptons in near earth orbit

Author: L. Djambazov, P. Giusti, G. Scolieri, I. Lopes, Dawei Zhao, P. G. Rancoita, E. Babucci, U. Becker, F. Vezzu, E. Perrin, F. J. Eppling, G. Barbier, S. M. Ting, S.C. Lee, R. Ionica, F. Palmonari, H. von Gunten, G. Esposito, Z.R. Dong, Federico Cindolo, Changgen Yang, H. T. Liu, Diego Casadei, Yu. Galaktionov, D. Vité, A. Lebedev, U. Roeser, G. Castellini, Dong-Chul Son, Z. L. Ren, J. Alcaraz, Guohuai Zhu, Yun Wang, S. Bizzaglia, A. Arefiev, P. Extermann, H. Hofer, W. Wallraff, Ilya Usoskin, Jing Wang, P. Levtchenko, P. Emonet, T. S. Dai, H. Anderhub, Waclaw Karpinski, E. Fiandrini, R. Becker, P. Cannarsa, R. R. McNeil, D. Rapin, C. Roissin, B.C. Wang, M. Pimenta, E. P. Velikhov, B. Zimmermann, V. Plyaskin, Roald Z. Sagdeev, B. Meillon, H. S. Chen, L. Baldini, J. Casaus, A. Hasan, E. Riihonen, Mauro Menichelli, K. Karlamaa, A. Mihul, Giovanna Bruni, G. Kenney, N. Produit, D. Grandi, M. Ribordy, S. Urpo, W. J. Burger, Merja Tornikoski, Markus Cristinziani, G. Schwering, A. Pesci, I. Vetlitsky, L.G. Yan, I. D'Antone, Y. H. Chang, Tengfei Song, W.Q. Gu, B. Bertucci, D. Barancourt, N. Dinu, V. Commichau, G. Laborie, P. Crespo, Mao-Zhi Yang, J. J. Torsti, M. Jongmanns, Antonino Zichichi, Adrian Biland, V. Postolache, Peter H. Fisher, T. Eronen, C. Camps, J. Berdugo, N. Fouque, J. P. Da Cunha, Massimo Gervasi, J. Vandenhirtz, H. F. Chen, F. Barao, S. Blasko, Zhenyu Zhang, H.L. Zhuang, G. Viertel, E. Shoumilov, Jose Maria Kenny, W. Hungerford, F. Velcea, Y.L. Chuang, O. Grimm, J.L. Yan, K. Wiik, P. Bene, H. Suter, J.P. Richeux, Tzihong Chiueh, V. Hermel, M. Buenerd, Timo Laitinen, M. Capell, A. Papi, Eun-Suk Seo, M. Pauluzzi, R. Siedling, G. Fluegge, W.Z. Zhu, Giovanni Ambrosi, L. Ao, M. Bourquin, D. Ren, G. Lu, C. Maña, V. Koutsenko, Eino Valtonen, Felicitas Pauss, R. Kossakowski, A. Klimentov, G.S. Sun, A. Contin, Samuel C.C. Ting, M. A. Huang, M. J. Boschini, M. Basile, K. Hangarter, Roberto Battiston, A. Pevsner, D. Luckey, F. Mayet, Ciaran Williams, J. Ulbricht, A. Schultz von Dratzig, P. Yeh, G. Laurenti, Claudia Cecchi, S. Waldmeier Wicki, Hao Zhang, Z.G. Chen, S. X. Wu, J. Ritakari, X. D. Cai, J. Trümper, V. Shoutko, Inkyu Park, M. Steuer, P.C. Xia, S.W. Ye, C.L. Liu, L. Bellagamba, G. Lamanna, J. Engelberg, Xiao-Dong Tang, J. P. Vialle, K. Lübelsmeyer, G.P. Barreira, M. Ionica, P. Azzarello, Z. Z. Xu, V. Pojidaev, B. Verlaat, G. Sartorelli, P. Berges, Giuseppe Levi, Lu Yuzhang, Ari Mujunen, Werner Lustermann, Behcet Alpat, J. D. Burger, Frank Raupach, A. Mourao, J.D. Deus, L. Brocco, G. Boella, N.A. Chernoplekov, Anselmo Margotti, W. Kim, M. Kraeber, J. Favier, Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Annecy de Physique des Particules (LAPP), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), AMS, Alcaraz, J, Alpat, B, Ambrosi, G, Anderhub, H, Ao, L, Arefiev, A, Azzarello, P, Babucci, E, Baldini, L, Basile, M, Barancourt, D, Barao, F, Barbier, G, Barreira, G, Battiston, R, Becker, R, Becker, U, Bellagamba, L, Béné, P, Berdugo, J, Berges, P, Bertucci, B, Biland, A, Bizzaglia, S, Blasko, S, Boella, G, Boschini, M, Bourquin, M, Brocco, L, Bruni, G, Buenerd, M, Burger, J, Burger, W, Cai, X, Camps, C, Cannarsa, P, Capell, M, Casadei, D, Casaus, J, Castellini, G, Cecchi, C, Chang, Y, Chen, H, Chen, Z, Chernoplekov, N, Chiueh, T, Chuang, Y, Cindolo, F, Commichau, V, Contin, A, Crespo, P, Cristinziani, M, Cunha, J, Dai, T, Deus, J, Dinu, N, Djambazov, L, D'Antone, I, Dong, Z, Emonet, P, Engelberg, J, Eppling, F, Eronen, T, Esposito, G, Extermann, P, Favier, J, Fiandrini, E, Fisher, P, Fluegge, G, Fouque, N, Galaktionov, Y, Gervasi, M, Giusti, P, Grandi, D, Grimm, O, Gu, W, Hangarter, K, Hasan, A, Hermel, V, Hofer, H, Huang, M, Hungerford, W, Ionica, M, Ionica, R, Jongmanns, M, Karlamaa, K, Karpinski, W, Kenney, G, Kenny, J, Kim, W, Klimentov, A, Kossakowski, R, Koutsenko, V, Kraeber, M, Laborie, G, Laitinen, T, Lamanna, G, Laurenti, G, Lebedev, A, Lee, S, Levi, G, Levtchenko, P, Liu, C, Liu, H, Lopes, I, Lu, G, Lu, Y, Lübelsmeyer, K, Luckey, D, Lustermann, W, Maña, C, Margotti, A, Mayet, F, Mcneil, R, Meillon, B, Menichelli, M, Mihul, A, Mourao, A, Mujunen, A, Palmonari, F, Papi, A, Park, I, Pauluzzi, M, Pauss, F, Perrin, E, Pesci, A, Pevsner, A, Pimenta, M, Plyaskin, V, Pojidaev, V, Postolache, V, Produit, N, Rancoita, P, Rapin, D, Raupach, F, Ren, D, Ren, Z, Ribordy, M, Richeux, J, Riihonen, E, Ritakari, J, Roeser, U, Roissin, C, Sagdeev, R, Sartorelli, G, Dratzig, A, Schwering, G, Scolieri, G, Seo, E, Shoutko, V, Shoumilov, E, Siedling, R, Son, D, Song, T, Steuer, M, Sun, G, Suter, H, Tang, X, Ting, S, Tornikoski, M, Torsti, J, Trümper, J, Ulbricht, J, Urpo, S, Usoskin, I, Valtonen, E, Vandenhirtz, J, Velcea, F, Velikhov, E, Verlaat, B, Vetlitsky, I, Vezzu, F, Vialle, J, Viertel, G, Vité, D, Gunten, H, Wicki, S, Wallraff, W, Wang, B, Wang, J, Wang, Y, Wiik, K, Williams, C, Wu, S, Xia, P, Yan, J, Yan, L, Yang, C, Yang, M, Ye, S, Yeh, P, Xu, Z, Zhang, H, Zhang, Z, Zhao, D, Zhu, G, Zhu, W, Zhuang, H, Zichichi, A, and Zimmermann, B
Subjects: Nuclear and High Energy Physics, Cosmic Rays, AMS, Cosmic ray, Electron, Astrophysics, Kinetic energy, 01 natural sciences, Spectral line, [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], Nuclear physics, FIS/05 - ASTRONOMIA E ASTROFISICA, AMS-01, 0103 physical sciences, Alpha Magnetic Spectrometer, AMS, 010306 general physics, 010303 astronomy & astrophysics, Physics, Earth's orbit, Cosmic rays: leptons, Cosmic Rays, cosmic rays, AMS-01, FIS/01 - FISICA SPERIMENTALE, Earth's magnetic field, 13. Climate action, High Energy Physics::Experiment, FIS/04 - FISICA NUCLEARE E SUBNUCLEARE, Lepton
Abstract: The lepton spectra in the kinetic energy ranges 0.2 to 40 GeV for e − and 0.2 to 3 GeV for e + were measured by the Alpha Magnetic Spectrometer (AMS) during space shuttle flight STS–91 at altitudes near 380 km. From the origin of the leptons two distinct spectra were observed: a higher energy spectrum and a substantial second spectrum with positrons much more abundant than electrons. Tracing leptons from the second spectra shows that most of these leptons travel for an extended period of time in the geomagnetic field and that the e + and e − originate from two complementary geographic regions.
Published: 2000

49. Helium in near earth orbit

Author: D. Vité, Peter H. Fisher, Yu. Galaktionov, J. Alcaraz, Roald Z. Sagdeev, D.X. Zhao, K. Karlamaa, A. Arefiev, S.W. Ye, E. Riihonen, W. Hungerford, M. A. Huang, R. R. McNeil, B. Meillon, V. Shoutko, G. Kenney, J. Ritakari, Y. H. Chang, J. Engelberg, C. Camps, G. Sartorelli, D. Barancourt, A. Mihul, Timo Laitinen, R. Ionica, Jorge Dias de Deus, W. Kim, H. von Gunten, P. G. Rancoita, V. Postolache, M. Pauluzzi, G. Lu, C. Maña, Werner Lustermann, Federico Cindolo, F. Mayet, G. Fluegge, Mao-Zhi Yang, D. Ren, A. Schultz von Dratzig, G. Barbier, W.Z. Zhu, W. J. Burger, A. Papi, J. Casaus, U. Roeser, M. Ribordy, G. Ambrosi, Y.L. Chuang, A. Contin, P. Levtchenko, M. Buenerd, X.W. Tang, M. Pimenta, W. Wallraff, T. S. Dai, F. Vezzu, B. Verlaat, Maria Ionica, G.S. Sun, Samuel C.C. Ting, Frank Raupach, E. Shoumilov, P. Berges, B.C. Wang, S. Urpo, Ari Mujunen, G. Bruni, H. Suter, P. Bene, Hengchang Liu, D. Rapin, C. Roissin, V. Plyaskin, G. Laurenti, S. Waldmeier Wicki, D. Grandi, A. Pevsner, Z. L. Ren, F. Velcea, Tao Song, G. Lamanna, M. J. Boschini, B. Bertucci, J. J. Torsti, Antonino Zichichi, Waclaw Karpinski, J. Berdugo, H. Anderhub, V. Commichau, R. Becker, Roberto Battiston, B. Alpat, N. Fouque, J.P. Richeux, Zhenghao Xu, M. Bourquin, A. Lebedev, Dong-Chul Son, E. Fiandrini, F. Palmonari, Yun Wang, G. Boella, P. Yeh, J.L. Yan, H.F. Chen, L. Brocco, Felicitas Pauss, L. Baldini, A. Pesci, H. S. Chen, J. Ulbricht, K. Wiik, R. Kossakowski, N.A. Chernoplekov, Nicolas Produit, K. Lübelsmeyer, S. X. Wu, M. Basile, P. Cannarsa, Hao Zhang, S. Blasko, M. Jongmanns, G. Castellini, E. P. Velikhov, B. Zimmermann, G.P. Barreira, K. Hangarter, H. L. Zhuang, Anselmo Margotti, Tzihong Chiueh, J. P. Da Cunha, Y.S. Lu, Inkyu Park, J.P. Vialle, Ciaran Williams, A. Klimentov, G. Laborie, L. Ao, M. Pohl, N. Dinu, Merja Tornikoski, Markus Cristinziani, M. Steuer, P.C. Xia, G. Viertel, D. Luckey, Jose Maria Kenny, J. Trümper, L. Djambazov, Paolo Zuccon, O. Grimm, T. Eronen, E. Babucci, U. Becker, I. Vetlitsky, S.C. Lee, Eun-Suk Seo, E. Perrin, M. Kraeber, F. J. Eppling, S. M. Ting, Changgen Yang, V. Koutsenko, Eino Valtonen, P. Giusti, Adrian Biland, G. Scolieri, G. Esposito, Z.R. Dong, Claudia Cecchi, Philipp Azzarello, I. Lopes, Massimo Gervasi, P. Emonet, S. Bizzaglia, Z.G. Chen, J. Favier, M. Capell, R. Siedling, X. D. Cai, C.L. Liu, L. Bellagamba, L.G. Yan, Ilya Usoskin, Jing Wang, J. Vandenhirtz, A. Hasan, Mauro Menichelli, G. Schwering, P. Extermann, W.Q. Gu, H. Hofer, F. Barao, V. Hermel, Zhidong Zhang, D. Casadei, I. D'Antone, Guohuai Zhu, J. D. Burger, A. Mourao, V. Pojidaev, Giuseppe Levi, Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Annecy de Physique des Particules (LAPP), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), AMS, Alcaraz, J, Alpat, B, Ambrosi, G, Anderhub, H, Ao, L, Arefiev, A, Azzarello, P, Babucci, E, Baldini, L, Basile, M, Barancourt, D, Barao, F, Barbier, G, Barreira, G, Battiston, R, Becker, R, Becker, U, Bellagamba, L, Béné, P, Berdugo, J, Berges, P, Bertucci, B, Biland, A, Bizzaglia, S, Blasko, S, Boella, G, Boschini, M, Bourquin, M, Brocco, L, Bruni, G, Buenerd, M, Burger, J, Burger, W, Cai, X, Camps, C, Cannarsa, P, Capell, M, Casadei, D, Casaus, J, Castellini, G, Cecchi, C, Chang, Y, Chen, H, Chen, Z, Chernoplekov, N, Chiueh, T, Chuang, Y, Cindolo, F, Commichau, V, Contin, A, Cristinziani, M, Cunha, J, Dai, T, Deus, J, Dinu, N, Djambazov, L, D'Antone, I, Dong, Z, Emonet, P, Engelberg, J, Eppling, F, Eronen, T, Esposito, G, Extermann, P, Favier, J, Fiandrini, E, Fisher, P, Fluegge, G, Fouque, N, Galaktionov, Y, Gervasi, M, Giusti, P, Grandi, D, Grimm, O, Gu, W, Hangarter, K, Hasan, A, Hermel, V, Hofer, H, Huang, M, Hungerford, W, Ionica, M, Ionica, R, Jongmanns, M, Karlamaa, K, Karpinski, W, Kenney, G, Kenny, J, Kim, W, Klimentov, A, Kossakowski, R, Koutsenko, V, Kraeber, M, Laborie, G, Laitinen, T, Lamanna, G, Laurenti, G, Lebedev, A, Lee, S, Levi, G, Levtchenko, P, Liu, C, Liu, H, Lopes, I, Lu, G, Lu, Y, Lübelsmeyer, K, Luckey, D, Lustermann, W, Maña, C, Margotti, A, Mayet, F, Mcneil, R, Meillon, B, Menichelli, M, Mihul, A, Mourao, A, Mujunen, A, Palmonari, F, Papi, A, Park, I, Pauluzzi, M, Pauss, F, Perrin, E, Pesci, A, Pevsner, A, Pimenta, M, Plyaskin, V, Pojidaev, V, Pohl, M, Postolache, V, Produit, N, Rancoita, P, Rapin, D, Raupach, F, Ren, D, Ren, Z, Ribordy, M, Richeux, J, Riihonen, E, Ritakari, J, Roeser, U, Roissin, C, Sagdeev, R, Sartorelli, G, Schultz&nbsp, von&nbsp, Dratzig, A, Schwering, G, Scolieri, G, Seo, E, Shoutko, V, Shoumilov, E, Siedling, R, Son, D, Song, T, Steuer, M, Sun, G, Suter, H, Tang, X, Ting, S, Tornikoski, M, Torsti, J, Trümper, J, Ulbricht, J, Urpo, S, Usoskin, I, Valtonen, E, Vandenhirtz, J, Velcea, F, Velikhov, E, Verlaat, B, Vetlitsky, I, Vezzu, F, Vialle, J, Viertel, G, Vité, D, Gunten, H, Wicki, S, Wallraff, W, Wang, B, Wang, J, Wang, Y, Wiik, K, Williams, C, Wu, S, Xia, P, Yan, J, Yan, L, Yang, C, Yang, M, Ye, S, Yeh, P, Xu, Z, Zhang, H, Zhang, Z, Zhao, D, Zhu, G, Zhu, W, Zhuang, H, Zichichi, A, Zimmermann, B, Zuccon, P, Ambrosi, Giovanni, Azzarello, Philipp, Bene, Pierre, Bourquin, Maurice, Cristinziani, Markus, Emonet, Pascal Philippe, Extermann, Pierre, Perrin, Eric, Pohl, Martin, Produit, Nicolas, Rapin, Divic Jean, Ribordy, Mathieu, Richeux, Jean-Pierre, and Vite, Davide
Subjects: Physics, Nuclear and High Energy Physics, Earth's orbit, Range (particle radiation), 010308 nuclear & particles physics, chemistry.chemical_element, Flux, ddc:500.2, 01 natural sciences, Spectral line, Nuclear physics, [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], FIS/05 - ASTRONOMIA E ASTROFISICA, FIS/01 - FISICA SPERIMENTALE, Earth's magnetic field, chemistry, 0103 physical sciences, Alpha Magnetic Spectrometer, Atomic physics, Cosmic rays: helium, Nuclear Experiment, Nucleon, 010303 astronomy & astrophysics, FIS/04 - FISICA NUCLEARE E SUBNUCLEARE, Helium
Abstract: The helium spectrum from 0.1 to 100 GeV/nucleon was measured by the Alpha Magnetic Spectrometer (AMS) during space shuttle flight STS-91 at altitudes near 380 km. Above the geomagnetic cutoff the spectrum is parameterized by a power law. Below the geomagnetic cutoff a second helium spectrum was observed. In the second helium spectra over the energy range 0.1 to 1.2 GeV/nucleon the flux was measured to be (6.3±0.9)×10 −3 ( m 2 sec sr ) −1 and more than ninety percent of the helium was determined to be 3He (at the 90% CL). Tracing helium from the second spectrum shows that about half of the 3He travel for an extended period of time in the geomagnetic field and that they originate from restricted geographic regions similar to protons and positrons.
Published: 2000

50. The matrix element method at next-to-leading order

Author: John M. Campbell, Walter T. Giele, and Ciaran Williams
Subjects: Physics, Particle physics, Nuclear and High Energy Physics, Basis (linear algebra), FOS: Physical sciences, Order (ring theory), Extension (predicate logic), Search for the Higgs boson, High Energy Physics - Experiment, High Energy Physics - Phenomenology, High Energy Physics - Experiment (hep-ex), High Energy Physics - Phenomenology (hep-ph), Applied mathematics, Matrix element, Perturbation theory (quantum mechanics), Lepton, Communication channel
Abstract: This paper presents an extension of the matrix element method to next-to-leading order in perturbation theory. To accomplish this we have developed a method to calculate next-to-leading order weights on an event-by-event basis. This allows for the definition of next-to-leading order likelihoods in exactly the same fashion as at leading order, thus extending the matrix element method to next-to-leading order. A welcome by-product of the method is the straightforward and efficient generation of unweighted next-to-leading order events. As examples of the application of our next-to-leading order matrix element method we consider the measurement of the mass of the Z boson and also the search for the Higgs boson in the four lepton channel., Comment: 33 pages, 9 figures : v2 matches published version, significant additions including discussion of missing energy applications
Full Text: View/download PDF

Catalog

Books, media, physical & digital resources

See catalog results

Searchworks

Select search scope, currently: Articles Catalog books, media & more in Jio Institute collections Articles journal articles & other e-resources

Search

Search Constraints

Refine your results

Search Limiters

Topic

Publication Year Range

Language

Publication Type

Journal

Database

Publisher

54 results on '"Ciaran Williams"'

Search Results

Catalog

Select search scope, currently: Articles

Catalog

books, media & more in Jio Institute collections

Articles

journal articles & other e-resources