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Journal ArticleDOI

First measurement of the total proton-proton cross-section at the LHC energy of √s = 7 TeV

01 Oct 2011-EPL (IOP Publishing)-Vol. 96, Iss: 2, pp 21002-21012
TL;DR: TOTEM has measured the differential cross-section for elastic proton-proton scattering at the LHC energy of analysing data from a short run with dedicated large-β* optics as discussed by the authors.
Abstract: TOTEM has measured the differential cross-section for elastic proton-proton scattering at the LHC energy of analysing data from a short run with dedicated large-β* optics. A single exponential fit with a slope B=(20.1±0.2stat±0.3syst) GeV−2 describes the range of the four-momentum transfer squared |t| from 0.02 to 0.33 GeV2. After the extrapolation to |t|=0, a total elastic scattering cross-section of (24.8±0.2stat±1.2syst) mb was obtained. Applying the optical theorem and using the luminosity measurement from CMS, a total proton-proton cross-section of (98.3±0.2stat±2.8syst) mb was deduced which is in good agreement with the expectation from the overall fit of previously measured data over a large range of center-of-mass energies. From the total and elastic pp cross-section measurements, an inelastic pp cross-section of was inferred.

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Citations
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Journal ArticleDOI
Vardan Khachatryan1, Albert M. Sirunyan1, Armen Tumasyan1, Wolfgang Adam  +2283 moreInstitutions (141)
TL;DR: Combined fits to CMS UE proton–proton data at 7TeV and to UEProton–antiproton data from the CDF experiment at lower s, are used to study the UE models and constrain their parameters, providing thereby improved predictions for proton-proton collisions at 13.
Abstract: New sets of parameters ("tunes") for the underlying-event (UE) modeling of the PYTHIA8, PYTHIA6 and HERWIG++ Monte Carlo event generators are constructed using different parton distribution functions. Combined fits to CMS UE data at sqrt(s) = 7 TeV and to UE data from the CDF experiment at lower sqrt(s), are used to study the UE models and constrain their parameters, providing thereby improved predictions for proton-proton collisions at 13 TeV. In addition, it is investigated whether the values of the parameters obtained from fits to UE observables are consistent with the values determined from fitting observables sensitive to double-parton scattering processes. Finally, comparisons of the UE tunes to "minimum bias" (MB) events, multijet, and Drell-Yan (q q-bar to Z / gamma* to lepton-antilepton + jets) observables at 7 and 8 TeV are presented, as well as predictions of MB and UE observables at 13 TeV.

686 citations

Journal ArticleDOI
Georges Aad1, Brad Abbott2, Jalal Abdallah3, Ovsat Abdinov4  +2812 moreInstitutions (207)
TL;DR: In this paper, an independent b-tagging algorithm based on the reconstruction of muons inside jets as well as the b tagging algorithm used in the online trigger are also presented.
Abstract: The identification of jets containing b hadrons is important for the physics programme of the ATLAS experiment at the Large Hadron Collider. Several algorithms to identify jets containing b hadrons are described, ranging from those based on the reconstruction of an inclusive secondary vertex or the presence of tracks with large impact parameters to combined tagging algorithms making use of multi-variate discriminants. An independent b-tagging algorithm based on the reconstruction of muons inside jets as well as the b-tagging algorithm used in the online trigger are also presented. The b-jet tagging efficiency, the c-jet tagging efficiency and the mistag rate for light flavour jets in data have been measured with a number of complementary methods. The calibration results are presented as scale factors defined as the ratio of the efficiency (or mistag rate) in data to that in simulation. In the case of b jets, where more than one calibration method exists, the results from the various analyses have been combined taking into account the statistical correlation as well as the correlation of the sources of systematic uncertainty.

362 citations

Journal ArticleDOI
01 Jan 2013-EPL
TL;DR: Antchev et al. as discussed by the authors measured the differential cross-section for proton-proton elastic scattering as a function of the four-momentum transfer squared t at the LHC energy of, under various beam and background conditions, luminosities, and Roman Pot positions.
Abstract: At the LHC energy of , under various beam and background conditions, luminosities, and Roman Pot positions, TOTEM has measured the differential cross-section for proton-proton elastic scattering as a function of the four-momentum transfer squared t. The results of the different analyses are in excellent agreement demonstrating no sizeable dependence on the beam conditions. Due to the very close approach of the Roman Pot detectors to the beam center (?5?beam) in a dedicated run with ?*?=?90?m, |t|-values down to 5?10?3?GeV2 were reached. The exponential slope of the differential elastic cross-section in this newly explored |t|-region remained unchanged and thus an exponential fit with only one constant B?=?(19.9???0.3)?GeV?2 over the large |t|-range from 0.005 to 0.2?GeV2 describes the differential distribution well. The high precision of the measurement and the large fit range lead to an error on the slope parameter B which is remarkably small compared to previous experiments. It allows a precise extrapolation over the non-visible cross-section (only 9%) to t?=?0. With the luminosity from CMS, the elastic cross-section was determined to be (25.4???1.1)?mb, and using in addition the optical theorem, the total pp cross-section was derived to be (98.6???2.2)?mb. For model comparisons the t-distributions are tabulated including the large |t|-range of the previous measurement (TOTEM Collaboration (Antchev G. et al), EPL, 95 (2011) 41001).

228 citations

Journal ArticleDOI
Johan Alme1, Johan Alme2, Hege Austrheim Erdal2, Hege Austrheim Erdal1, Håvard Helstrup2, Håvard Helstrup1, Kristin Fanebust Hetland1, Kristin Fanebust Hetland2, Bjarte Kileng2, Bjarte Kileng1, Sedat Altinpinar3, Sedat Altinpinar2, Øystein Djuvsland3, Dominik Fehlker3, Dominik Fehlker2, Øystein Senneset Haaland3, Meidana Huang2, Meidana Huang3, Rune Langøy2, Rune Langøy3, Jørgen André Lien2, Jørgen André Lien3, L. Liu3, L. Liu2, Joakim Nystrand2, Joakim Nystrand3, Ketil Røed3, Ketil Røed2, Dieter Røhrich3, Dieter Røhrich2, Kyrre Skjerdal3, Kyrre Skjerdal2, Artur Krzysztof Szostak3, Artur Krzysztof Szostak2, Kjetil Ullaland2, Kjetil Ullaland3, G. Ovrebekk3, G. Ovrebekk2, Boris Wagner3, Boris Wagner2, Shiming Yang3, Shiming Yang2, Olja Dordic4, Olja Dordic2, Gyulnara Eyyubova2, Gyulnara Eyyubova4, Henning Kværnø2, Henning Kværnø4, Svein Lindal2, Svein Lindal4, Gunnar Løvhøiden4, Gunnar Løvhøiden2, Jovan Milosevic2, Jovan Milosevic4, Mads Stormo Nilsson4, Mads Stormo Nilsson2, Henrik Qvigstad4, Henrik Qvigstad2, Matthias Richter2, Matthias Richter4, Toralf Bernhard Skaali4, Toralf Bernhard Skaali2, Trine Spedstad Tveter4, Trine Spedstad Tveter2, Jon Christopher Wikne2, Jon Christopher Wikne4, Betty Abelev5, Betty Abelev2, Jaroslav Adam6, Dagmar Adamová7, Dagmar Adamová2, Andrew Marshall Adare2, Andrew Marshall Adare8, Madan M. Aggarwal2, Madan M. Aggarwal9, Gianluca Aglieri Rinella10, Gianluca Aglieri Rinella2, A. G. Agocs2, A. G. Agocs11, Andrea Agostinelli, Saul Aguilar Salazar12, Saul Aguilar Salazar2, Zubayer Ahammed2, Zubayer Ahammed13, Nazeer Ahmad2, Nazeer Ahmad14, A. Ahmad Masoodi2, A. Ahmad Masoodi14, Sang Un Ahn12, Sang Un Ahn2, Alexander Akindinov2, Dimitry Aleksandrov2, Dimitry Aleksandrov15, Bruno Alessandro 
TL;DR: The single- and double-diffractive cross sections were calculated combining relative rates of diffraction with inelastic cross sections and compared to previous measurements at proton–antiproton and proton-proton colliders at lower energies, to measurements by other experiments at the LHC, and to theoretical models.
Abstract: Measurements of cross sections of inelastic and diffractive processes in proton--proton collisions at LHC energies were carried out with the ALICE detector. The fractions of diffractive processes in inelastic collisions were determined from a study of gaps in charged particle pseudorapidity distributions: for single diffraction (diffractive mass $M_X 3$) $\sigma_{\rm DD}/\sigma_{\rm INEL} = 0.11 \pm 0.03, 0.12 \pm 0.05$, and $0.12^{+0.05}_{-0.04}$, respectively at $\sqrt{s} = 0.9, 2.76$, and 7 TeV. To measure the inelastic cross section, beam properties were determined with van der Meer scans, and, using a simulation of diffraction adjusted to data, the following values were obtained: $\sigma_{\rm INEL} = 62.8^{+2.4}_{-4.0} (model) \pm 1.2 (lumi)$ mb at $\sqrt{s} =$ 2.76 TeV and $73.2^{+2.0}_{-4.6} (model) \pm 2.6 (lumi)$ mb at $\sqrt{s}$ = 7 TeV. The single- and double-diffractive cross sections were calculated combining relative rates of diffraction with inelastic cross sections. The results are compared to previous measurements at proton--antiproton and proton--proton colliders at lower energies, to measurements by other experiments at the LHC, and to theoretical models.

227 citations

Journal ArticleDOI
Vardan Khachatryan1, Albert M. Sirunyan1, Armen Tumasyan1, Wolfgang Adam  +2122 moreInstitutions (140)
TL;DR: In this article, the normalized differential cross section for top quark pair (tt) production is measured in pp collisions at a centre-of-mass energy of 8TeV at the CERN LHC using the CMS detector in data corresponding to an integrated luminosity of 19.7fb^(−1).
Abstract: The normalized differential cross section for top quark pair (tt) production is measured in pp collisions at a centre-of-mass energy of 8TeV at the CERN LHC using the CMS detector in data corresponding to an integrated luminosity of 19.7fb^(−1). The measurements are performed in the lepton+jets (e/μ +jets) and in the dilepton (e^+e^−, μ^+μ^−, and e^±μ^∓) decay channels. The tt cross section is measured as a function of the kinematic properties of the charged leptons, the jets associated to b quarks, the top quarks, and the tt system. The data are compared with several predictions from perturbative quantum chromodynamic up to approximate next-to-next-to-leading-order precision. No significant deviations are observed relative to the standard model predictions.

215 citations

References
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04 Dec 2013
TL;DR: Beringer et al. as mentioned in this paper presented a review of particle physics using data from previous editions, plus 2658 new measurements from 644 papers, and summarized searches for hypothetical particles such as Higgs bosons, heavy neutrinos, and supersymmetric particles.
Abstract: Phys. Rev. D 86, 010001 REVIEW OF PARTICLE PHYSICS* Particle Data Group Abstract This biennial Review summarizes much of particle physics. Using data from previous editions, plus 2658 new measurements from 644 papers, we list, evaluate, and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as Higgs bosons, heavy neutrinos, and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as the Standard Model, particle detectors, probability, and statistics. Among the 112 reviews are many that are new or heavily revised including those on Heavy-Quark and Soft-Collinear Effective Theory, Neutrino Cross Section Measurements, Monte Carlo Event Generators, Lattice QCD, Heavy Quarkonium Spectroscopy, Top Quark, Dark Matter, V cb & V ub , Quantum Chromodynamics, High-Energy Collider Parameters, Astrophysical Constants, Cosmological Parameters, and Dark Matter. A booklet is available containing the Summary Tables and abbreviated versions of some of the other sections of this full Review. All tables, listings, and reviews (and errata) are also available on the Particle Data Group website: http://pdg.lbl.gov. DOI: 10.1103/PhysRevD.86.010001 The 2012 edition of Review of Particle Physics is published for the Particle Data Group as article 010001 in volume 86 of Physical Review D. This edition should be cited as: J. Beringer et al. (Particle Data Group), Phys. Rev. D 86, 010001 (2012). c 2012 Regents of the University of California ∗ The publication of the Review of Particle Physics is supported by the Director, Office of Science, Office of High Energy and Nuclear Physics, the Division of High Energy Physics of the U.S. Department of Energy under Contract No. DE–AC02–05CH11231; by the U.S. National Science Foundation under Agreement No. PHY-0652989; by the European Laboratory for Particle Physics (CERN); by an implementing arrangement between the governments of Japan (MEXT: Ministry of Education, Culture, Sports, Science and Technology) and the United States (DOE) on cooperative research and development; and by the Italian National Institute of Nuclear Physics (INFN).

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Koji Nakamura1, K. Hagiwara, Ken Ichi Hikasa2, Hitoshi Murayama3  +180 moreInstitutions (92)
TL;DR: In this article, a biennial review summarizes much of particle physics using data from previous editions, plus 2158 new measurements from 551 papers, they list, evaluate and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons.
Abstract: This biennial Review summarizes much of particle physics. Using data from previous editions, plus 2158 new measurements from 551 papers, we list, evaluate, and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons. We also summarize searches for hypothetical particles such as Higgs bosons, heavy neutrinos, and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as the Standard Model, particle detectors, probability, and statistics. Among the 108 reviews are many that are new or heavily revised including those on neutrino mass, mixing, and oscillations, QCD, top quark, CKM quark-mixing matrix, V-ud & V-us, V-cb & V-ub, fragmentation functions, particle detectors for accelerator and non-accelerator physics, magnetic monopoles, cosmological parameters, and big bang cosmology.

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Journal ArticleDOI
G. Anelli1, G. Antchev1, P. Aspell1, V. Avati2, V. Avati1, Maria Grazia Bagliesi3, Vincenzo Berardi4, M. Berretti3, V. Boccone5, Ubaldo Bottigli3, M. Bozzo5, Erik Brücken6, A. Buzzo5, F. Cafagna4, M. Calicchio4, F Capurro5, M. G. Catanesi4, P. Catastini3, Roberto Cecchi3, S. Cerchi5, R. Cereseto5, Maria Agnese Ciocci3, S. Cuneo5, C. Da Via7, Eric David1, Mario Deile1, E. Dimovasili2, E. Dimovasili1, M. Doubrava8, K. Eggert1, V. K. Eremin, Fabrizio Ferro5, A. Foussat1, M Galuska8, Francisco Garcia6, F. Gherarducci3, Simone Giani1, V. Greco3, Jasmine Hasi7, F. Haug1, J. Heino6, T. Hilden6, Pierre Jarron1, C. Joram1, Juha Kalliopuska6, J. Kaplon1, J. Kaspar1, J. Kaspar9, V. Kundrát9, K. Kurvinen6, J. M. Lacroix1, S. Lami3, Giuseppe Latino3, R. Lauhakangas6, E. Lippmaa10, Milos Lokajicek9, M. Lo Vetere5, F. Lucas Rodríguez1, D. Macina1, M. Macri5, C. Magazzù3, G. Magazzu3, A. Magri5, G. Maire1, A. Manco5, Mario Meucci3, S. Minutoli5, A. Morelli5, P. Musico5, M. Negri5, H. Niewiadomski1, H. Niewiadomski2, E. Noschis1, G. Notarnicola4, Eraldo Oliveri3, F. Oljemark6, R. Orava6, M. Oriunno1, A. L. Perrot1, K. Osterberg6, Riccardo Paoletti3, E. Pedreschi3, J. Petajajarvi6, P. Pollovio5, M. Quinto4, E. Radermacher1, E. Radicioni4, S. Rangod1, Federico Ravotti1, G. Rella4, Enrico Robutti5, L. Ropelewski1, G. Ruggiero1, A. Rummel10, H. Saarikko6, G. Sanguinetti3, A. Santroni5, A. Scribano3, G. Sette5, W. Snoeys1, F. Spinella3, P. Squillacioti3, A. Ster, C. Taylor11, A. Tazzioli3, Diego Torazza5, A. Trovato5, A. Trummal10, Nicola Turini3, Vaclav Vacek8, Vaclav Vacek1, N. Van Remortel6, Václav Vinš8, Stephen Watts7, J. Whitmore2, J. Wu1 
TL;DR: The TOTEM Experiment as discussed by the authors measured the total pp cross-section with the luminosity-independent method and studied elastic and diffractive scattering at the LHC using two tracking telescopes, T1 and T2.
Abstract: The TOTEM Experiment will measure the total pp cross-section with the luminosity-independent method and study elastic and diffractive scattering at the LHC. To achieve optimum forward coverage for charged particles emitted by the pp collisions in the interaction point IP5, two tracking telescopes, T1 and T2, will be installed on each side in the pseudorapidity region 3.1 ≤ |η| ≤ 6.5, and Roman Pot stations will be placed at distances of ±147 m and ±220 m from IP5. Being an independent experiment but technically integrated into CMS, TOTEM will first operate in standalone mode to pursue its own physics programme and at a later stage together with CMS for a common physics programme. This article gives a description of the TOTEM apparatus and its performance.

345 citations


"First measurement of the total prot..." refers background in this paper

  • ...To detect leading protons scattered at very small angles, si licon sensors are placed in movable beam-pipe insertions – so-called “Roman Pots” (RP) – located symmetri cally on either side of the LHC interaction point IP5 at distances of 215 – 220 m from the IP [16]....

    [...]

Journal ArticleDOI
TL;DR: These predictions are based on an extensive study of possible analytic parametrizations invoking the largest hadronic dataset available at t=0.1 TeV, and on total cross sections for gammap-->hadrons at cosmic-ray energies and forgammagamma -->hadrons up to sqrt[s]=1 Tev.
Abstract: We present predictions on the total cross sections and on the rho parameter for present and future pp and (-)pp colliders, and on total cross sections for gammap-->hadrons at cosmic-ray energies and for gammagamma-->hadrons up to sqrt[s]=1 TeV. These predictions are based on an extensive study of possible analytic parametrizations invoking the largest hadronic dataset available at t=0. The uncertainties on total cross sections reach 1.9% at the Relativistic Heavy Ion Collider, 3.1% at the Tevatron, and 4.8% at the Large Hadron Collider, whereas those on the rho parameter are, respectively, 5.4%, 5.2%, and 5.4%.

229 citations


"First measurement of the total prot..." refers background or result in this paper

  • ...Taking the COMPETE prediction [30] of 0....

    [...]

  • ...5, the values of the TOTEM total and elastic cross-sections are compared with results at lower energies and from cosmic rays together with an overall fit of the COMPETE collaboration [30]....

    [...]

  • ...5: Compilation of total (σtot), inelastic (σinel) and elastic (σel) cross-section measurements [30, 31, 32, 33, 34, 35]....

    [...]

Journal ArticleDOI
TL;DR: The absolute scale of the cross-section was established by determination of the effective density of the colliding beans in their overlap region as mentioned in this paper, which was deduced by extrapolation of the elastic differential crosssection to the forward direction and by application of the optical theorem.

209 citations


"First measurement of the total prot..." refers background in this paper

  • ...The observation of the rise of the total cross-section with e nergy was one of the highlights at the ISR, the first CERN collider [1, 2, 3, 4]....

    [...]

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Johan Alme, Johan Alme, Hege Austrheim Erdal, Hege Austrheim Erdal, Håvard Helstrup, Håvard Helstrup, Kristin Fanebust Hetland, Kristin Fanebust Hetland, Bjarte Kileng, Bjarte Kileng, Sedat Altinpinar, Sedat Altinpinar, Øystein Djuvsland, Dominik Fehlker, Dominik Fehlker, Øystein Senneset Haaland, Meidana Huang, Meidana Huang, Rune Langøy, Rune Langøy, Jørgen André Lien, Jørgen André Lien, L. Liu, L. Liu, Joakim Nystrand, Joakim Nystrand, Ketil Røed, Ketil Røed, Dieter Røhrich, Dieter Røhrich, Kyrre Skjerdal, Kyrre Skjerdal, Artur Krzysztof Szostak, Artur Krzysztof Szostak, Kjetil Ullaland, Kjetil Ullaland, G. Ovrebekk, G. Ovrebekk, Boris Wagner, Boris Wagner, Shiming Yang, Shiming Yang, Olja Dordic, Olja Dordic, Gyulnara Eyyubova, Gyulnara Eyyubova, Henning Kværnø, Henning Kværnø, Svein Lindal, Svein Lindal, Gunnar Løvhøiden, Gunnar Løvhøiden, Jovan Milosevic, Jovan Milosevic, Mads Stormo Nilsson, Mads Stormo Nilsson, Henrik Qvigstad, Henrik Qvigstad, Matthias Richter, Matthias Richter, Toralf Bernhard Skaali, Toralf Bernhard Skaali, Trine Spedstad Tveter, Trine Spedstad Tveter, Jon Christopher Wikne, Jon Christopher Wikne, Betty Abelev, Betty Abelev, Jaroslav Adam, Dagmar Adamová, Dagmar Adamová, Andrew Marshall Adare, Andrew Marshall Adare, Madan M. Aggarwal, Madan M. Aggarwal, Gianluca Aglieri Rinella, Gianluca Aglieri Rinella, A. G. Agocs, A. G. Agocs, Andrea Agostinelli, Saul Aguilar Salazar, Saul Aguilar Salazar, Zubayer Ahammed, Zubayer Ahammed, Nazeer Ahmad, Nazeer Ahmad, A. Ahmad Masoodi, A. Ahmad Masoodi, Sang Un Ahn, Sang Un Ahn, Alexander Akindinov, Dimitry Aleksandrov, Dimitry Aleksandrov, Bruno Alessandro