DOCSLIB.ORG

Physics of W Bosons and Four-Fermion Processes at LEP2/TESLA Energies Two-Fermion Production at Electron-Positron Colliders UBS?

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Physics of W Bosons and Four-Fermion Processes at LEP2/TESLA Energies Two-Fermion Production at Electron-Positron Colliders UBS? PL0002438 145 Physics of W Bosons and Four-Fermion Processes at LEP2/TESLA Energies S. Jadach, Z. Wa.s, and M. Skrzypek The calculative framework for predictions of 4-fermion final states at LEP including complete first order radiative corrections for dominant diagrams was established. • KORALW — Version 1.42, featuring the simulation of all four-fermion processes at LEP2, is now in full use at LEP2, making it the only available calculation featuring ^(7) radiation for the initial state with finite px photons in the YFS-style of exclusive exponentiation. It is published in Comp. Phys. Commun. 119 (1999) 272. We have recently begun the development of its tandem use with the YFSWW3 exact O(a) exponentiated calculation of the CC03 signal process for the WW pair production and decay. This tandem is the only MC event generator calculation with the demonstrated capability to reach the 0.5% tag called-out by the 1996 CERN Yellow Book Report on LEP2 Physics for the WW pair production cross section. • YFSZZ — We continued with the support, of LEP2 users, for our work on YFS exponentiated MC for ZZ pair production. Its results continue to be used for setting limits on anomalous couplings as presented by the LEP collaborations at the 1998 Rochester Conference. Issues such as the proper SM coupling constant inputs at LEP2, etc., have been resolved by direct interaction with LEP users, so that the results quoted by the LEP collaborations based on this calculation are in fact correct. • YFSWW3 — We continued the development of the tandem use, with KORALW1.42, of our published exact O(a) YFS exponentiated CC03 MC for the signal WW processes at LEP2, which is the only such four-fermion MC with these corrections in existence. With its version 3-1.12, we cross-checked the semi-analytical work of Beenakker et al. (Nucl. Phys. B548 (1999) 3, Phys. Lett. B435 (1999) 233) on the effect of FSR in the WW pair production and decay - we find good correspondence between our results and this semi-analytical work. We have formulated a precise statement of the gauge-invariance and renormalization scheme independence of our approach to the tandem use of YFSWW3 and KORALW1.42, which we refer to as the leading pole approximation (LPA). In this way, we have the only scheme realized by MC event generators with the proven capability to reach the 0.5% tag called-out by the 1996 CERN Yellow Book Report on LEP2 Physics for the WW pair production cross section and which is manifestly gauge-invariant and independent of the renormalization scheme. Two-Fermion Production at Electron-Positron Colliders UBS? S. Jadach and Z. Wa,s == o H§ A new form of exponentiation based on spin amplitudes was established. Predictions for LEPS = Q_ observables at precision of 0.2% were calculated thanks to the control of effects such as initial-final ^^ state interference. The results were incorporated into public packages for Monte Carlo simulations. ^= • KK - as a replacement for Monte Carlo packages such as KORALZ: we have published (Phys. Lett. B449 (1999) 97 and hep-ph/9912214) our new approach to YFS exponentiated MC's based on a new realization of the cancellation of infrared singularities to all orders in a in which the real emission is also isolated at the amplitude level. We refer to these new series of calculations as ICIC. The applications to the Z-return events at LEP2 and to the precision Z line-shape analysis at LEP1 (Phys. Lett. B456 (1999) 77; ibid B465 (1999) 254), wherein the initial-final interference radiative effects are needed in the presence of n(-y) radiation, are already well under way. 146 • KORALZ - We have also released the version 4.04 of KORALZ ( hep-ph/9905205 ) for use at LEP2 with appropriate upgrades and extensions of its various modules. For example the LEP2- compatible DIZET6.X EW library has been implemented. For, while KK.f is the calculation which will ultimately replace KORALZ, the KORALZ 4.04 version will continue to be used in LEP1 and in LEP2 future data analysis. Special tools for study of anomalous W-W-7 (hep- ph/9905225) and r-r-7 couplings necessary in experimental search for new phenomena were also published (hep-ph/9905207). PL0002440 Old and New Physics at Hadron Colliders S. Jadach and E. Richter-Was Our participation in the LHC program consists both of rather more theoretical activities related to techniques of summation of infrared QCD singularities and some which are rather more practical, being related to the study of possible signatures of new phenomena and their backgrounds in the explicit context of the future detector properties. The following activities should be mentioned: • LHCYFS - We published (Mod. Phys. Lett. A14 (1999) 491) the recently developed procedure for realising n(G) radiative effects in our new YFS exponentiated approach to QCD without double counting the LL infrared effects already present in DGLAP evolved structure functions. This is a crucial step for developing hadron level MC-s of the LHCYFS-type in which multiple soft gluons are produced on an event-per-event basis for incoming hadron beams as opposed to the incoming fundamental particle beams studied in our earlier works. Our work to realize this DGLAP-YFS synthesization by MC methods continues. • ATLFAST - the ATLFAST package including fast parametrisation of the charged tracks recon- struction in the Inner Detector and several algorithms for the reconstruction of jets is in wide use by the ATLAS collaboration. It was especially instrumental in the preparation of the AT- LAS Overall Performance TDR (CERN/LHCC/99-15) and is available together with the long write-up from the ATLAS www page http://atlasinfo.cern.ch/Atlas/GROUPS/PHYSICS/physics.html under entry: Tools for physics simulation. • LHC versus Tevatron potential for the Higgs searches — The discovery potentials for the Teva- tron and the LHC for the Higgs in the mass range 100-130 GeV have been studied intensively using the ATLFAST and related programs. We have estimated that, as concerns the comparison of the Tevatron and LHC for the 100-130 GeV Higgs mass range in the WH and ZH channels, the LHC has a signal 5 times larger than the Tevatron in the WH channel for a given integrated luminosity. The Tevatron, however, has a more favourable background. For the ZH channel, the key issue is the ability to reduce the QCD background and this applies to both the Tevatron and the LHC experiments, although it has been neglected in Tevatron studies to date. For the Tevatron, which relies on a combination of several channels for its Higgs discovery potential, confirmation of the feasibility of the ZH channel in view of the QCD background is crucial and our work in this arena continues accordingly. The results of these studies become an important factor in the discussion between the Tevatron and LHC physicists. Several very interesting stud- ies related to these topics were performed, concerning reliability of the parton shower Monte Carlo in predicting heavy flavour content of multijet events and W/Z + multi b-jet production..
Load more

Recommended publications
  • Supersymmetry Searches at the Tevatron
    SUPERSYMMETRY SEARCHES AT THE TEVATRON For CDF and DØ collaborations R. Demina Department of Physics and Astronomy, University of Rochester, Rochester, USA, 14627 CDF and DØ collaborations analyzed up to 200 pb-1 of the delivered data in search for different supersymmetry signatures, so far with negative results. We present results on searches for chargino and neutralino associated production, squarks and gluinos, sbottom quarks, gauge mediated SUSY breaking and long lived heavy particles. Supersymmetry1 is a popular extension of the Standard Model originally suggested over 25 years ago. It postulates the symmetry between fermionic and bosonic degrees of freedom. As a result a variety of hypothetical particles is introduced. With presently available experimental data physicists were able to prove that if supersymmetric particles exist they must be heavier than their Standard Model partners2. In other words the Supersymmetry is broken. One possible exception is supersymmetric top quark (stop), which still has a chance to be lighter or of the same mass as top quark. With 2-4 fb-1 of data Tevatron experiments will be able to extend the limit on stop mass above that of top quark or discover it and thus establish the Supersymmetry3. Theory suggests several possible scenarios of Supersymmetry breaking mediated by gravitational or gauge interactions. In gravity mediated scenarios the number of free parameters in the model is reduced to five because of the unification of masses and couplings imposed at the grand unification scale. These parameters are M0 (M½) – masses of all bosons (fermions) at GUT scale, A0- trilinear coupling and µ0 – something Higgs and tan(β) – ratio of vacuum expectations of the Higgs doublet.
    [Show full text]
  • Three Extra Mirror Or Sequential Families: a Case for Heavy Higgs and Inert Doublet
    Three Extra Mirror or Sequential Families: a Case for Heavy Higgs and Inert Doublet Homero Mart´ınez,1 Alejandra Melfo,2, 3 Fabrizio Nesti,4 and Goran Senjanovi´c2 1CEA, Saclay, DSM-IRFU-SPP, France 2ICTP, Trieste, Italy 3U. de Los Andes, M´erida, Venezuela 4U. di Ferrara, Ferrara, Italy (Dated: October 24, 2018) We study the possibility of the existence of extra fermion families and an extra Higgs doublet. We find that requiring the extra Higgs doublet to be inert leaves space for three extra families, allowing for mirror fermion families and a dark matter candidate at the same time. The emerging scenario is very predictive: it consists of a Standard Model Higgs boson, with mass above 400 GeV, heavy new quarks between 340 and 500 GeV, light extra neutral leptons, and an inert scalar with a mass below MZ . PACS numbers: 14.65.Jk, 12.60.Fr, 14.60.Hi, 14.60.St Introduction. It may not be well known that the idea with regard to high precision analysis they behave exactly of parity restoration in weak interactions is as old as as ordinary fermions, and thus a reader who is uncom- the suggestion of its breakdown. In their classic paper, fortable with the above setbacks can view our study as Lee and Yang [1] proposed the existence of what we will referring to the more general question of whether the SM call mirror fermions, so as to make the world left-right can host three (or more) extra families. symmetric at high energies. By this they meant another If one defines the SM by its structure, i.e.
    [Show full text]
  • Bright Prospects for Tevatron Run II
    INTERNATIONAL JOURNAL OF HIGH-ENERGY PHYSICS CERN COURIER VOLUME 43 NUMBER 1 JANUARY/FEBRUARY 2003 Bright prospects for Tevatron Run II JLAB Virginia laboratory delivers terahertz light p6 ^^^J Modular and expandable power supplies WÊ H Communications via TCP/IP içert. n_.___910S.CAEN '^^^*aBOKS^^^^ • ÊÊÊ WÊÊÊSêSê É TÏSjj à OPC Server to ease integration in DCS J Directly interfaced to JCOP Framework p " j^pj ^ ^^^^ Wa9neticFie,dand^ ^^HTJHj^^^^^^^^^^^^^^^^^^^^^^E' ' tfHl far IM Éfefi-*il * CAEN: your largest choice of HV & LV )^ H MULTICHANNEL POWER SUPPLIES CONTENTS Covering current developments in high- energy physics and related fields worldwide CERN Courier (ISSN 0304-288X) is distributed to member state governments, institutes and laboratories affiliated with CERN, and to their personnel. It is published monthly, except for January and August, in English and French editions. The views expressed are CERN not necessarily those of the CERN management. Editors James Gillies and Christine Sutton CERN, 1211 Geneva 23, Switzerland Email [email protected] Fax+41 (22) 782 1906 Web cerncourier.com COURIER Advisory Board R Landua (Chairman), F Close, E Lillest0l, VOLUME 43 NUMBER 1 JANUARY/FEBRUARY 2003 H Hoffmann, C Johnson, K Potter, P Sphicas Laboratory correspondents: Argonne National Laboratory (US): D Ayres Brookhaven, National Laboratory (US): PYamin Cornell University (US): D G Cassel DESY Laboratory (Germany): Ilka Flegel, P Waloschek Fermi National Accelerator Laboratory (US): Judy Jackson GSI Darmstadt (Germany): G Siegert INFN
    [Show full text]
  • Tevatron Accelerator Physics and Operation Highlights A
    FERMILAB-CONF-11-129-APC TEVATRON ACCELERATOR PHYSICS AND OPERATION HIGHLIGHTS A. Valishev for the Tevatron group, FNAL, Batavia, IL 60510, U.S.A. Abstract Table 1: Integrated luminosity performance by fiscal year. The performance of the Tevatron collider demonstrated FY07 FY08 FY09 FY10 continuous growth over the course of Run II, with the peak luminosity reaching 4×1032 cm-2 s-1, and the weekly Total integral (fb-1) 1.3 1.8 1.9 2.47 -1 integration rate exceeding 70 pb . This report presents a review of the most important advances that contributed to Until the middle of calendar year 2009, the luminosity this performance improvement, including beam dynamics growth was dominated by improvements of the antiproton modeling, precision optics measurements and stability production rate [2], which remains stable since. control, implementation of collimation during low-beta Performance improvements over the last two years squeeze. Algorithms employed for optimization of the became possible because of implementation of a few luminosity integration are presented and the lessons operational changes, described in the following section. learned from high-luminosity operation are discussed. Studies of novel accelerator physics concepts at the Tevatron are described, such as the collimation techniques using crystal collimator and hollow electron beam, and compensation of beam-beam effects. COLLIDER RUN II PERFORMANCE Tevatron collider Run II with proton-antiproton collisions at the center of mass energy of 1.96 TeV started in March 2001. Since then, 10.5 fb-1 of integrated luminosity has been delivered to CDF and D0 experiments (Fig. 1). All major technical upgrades of the accelerator complex were completed by 2007 [1].
    [Show full text]
  • 01Ii Beam Line
    STA N FO RD LIN EA R A C C ELERA TO R C EN TER Fall 2001, Vol. 31, No. 3 CONTENTS A PERIODICAL OF PARTICLE PHYSICS FALL 2001 VOL. 31, NUMBER 3 Guest Editor MICHAEL RIORDAN Editors RENE DONALDSON, BILL KIRK Contributing Editors GORDON FRASER JUDY JACKSON, AKIHIRO MAKI MICHAEL RIORDAN, PEDRO WALOSCHEK Editorial Advisory Board PATRICIA BURCHAT, DAVID BURKE LANCE DIXON, EDWARD HARTOUNI ABRAHAM SEIDEN, GEORGE SMOOT HERMAN WINICK Illustrations TERRY ANDERSON Distribution CRYSTAL TILGHMAN The Beam Line is published quarterly by the Stanford Linear Accelerator Center, Box 4349, Stanford, CA 94309. Telephone: (650) 926-2585. EMAIL: [email protected] FAX: (650) 926-4500 Issues of the Beam Line are accessible electroni- cally on the World Wide Web at http://www.slac. stanford.edu/pubs/beamline. SLAC is operated by Stanford University under contract with the U.S. Department of Energy. The opinions of the authors do not necessarily reflect the policies of the Stanford Linear Accelerator Center. Cover: The Sudbury Neutrino Observatory detects neutrinos from the sun. This interior view from beneath the detector shows the acrylic vessel containing 1000 tons of heavy water, surrounded by photomultiplier tubes. (Courtesy SNO Collaboration) Printed on recycled paper 2 FOREWORD 32 THE ENIGMATIC WORLD David O. Caldwell OF NEUTRINOS Trying to discern the patterns of neutrino masses and mixing. FEATURES Boris Kayser 42 THE K2K NEUTRINO 4 PAULI’S GHOST EXPERIMENT A seventy-year saga of the conception The world’s first long-baseline and discovery of neutrinos. neutrino experiment is beginning Michael Riordan to produce results. Koichiro Nishikawa & Jeffrey Wilkes 15 MINING SUNSHINE The first results from the Sudbury 50 WHATEVER HAPPENED Neutrino Observatory reveal TO HOT DARK MATTER? the “missing” solar neutrinos.
    [Show full text]
  • Fermi National Accelerator Laboratory 132 Nsec Bunch Spacing in The
    Fermi National Accelerator Laboratory FERMILAR-TM-1920 132 nsec Bunch Spacing in the Tevatron Proton-Antiproton Collider S. D. Holmes et al. Fermi National Accelerator Laboratory P.O. Box 500, Batavia, Illinois 60510 December 1994 0 Operated by Universities Research Association Inc. under Contract No. DE-ACOZ-76CH030W with the United States Department of Energy Disclaimer This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infn’nge privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof 132 nsec Bunch Spacing in the Tevatron Proton-Antiproton Collider SD. Holmes, J. Holt, J.A. Johnstone, J. Marriner, M. Martens, D. McGinnis Fermi National Accelerator Laboratory December 23, 1994 Abstract Following completion of the Fermilah Main Injector it is expected that the Tevatron proton-antiproton collider will be operating at a luminosity in excess of 5x1031 cm-%ec-1 with 36 proton and antiproton bunches spaced at 396 nsec. At this luminosity, each of the experimental detectors will see approximately 1.3 interactions per crossing.
    [Show full text]
  • MASTER -••••-".>; I~CN of TH;3 DOCUMENT 18 Unlfmfts DISCLAIMER
    i ' Do^y^W-S- 2 Progress report 2.1 The D0 Experiment The D0 detector had its first data run in the period May 1992 till June 1993. The first two thirds of the run period were characterized by low luminosity and frequent machine development periods. The luminosity gradually climbed, and the machine ultimately delivered 31 pb_1 to the experiment. The detector performed admirably well, and data analysis tracked data taking closely. The overall D0 efficiency was 54% and 16.7 pb_1 of data were collected; due to high backgrounds during Main Ring injection and transition, and beam gas interactions in the MR pipe that intersects our calorimeter, triggers in D0 were vetoed for about 29% of the store time; data acquisition busy (7%), experiment down time (5%), and run startup overhead (5%) added another 17% to the inefficiency. Many cycles of reconstruction software upgrade were done as experience with real data was gained, bugs were corrected, and new data corrections were added. First results were presented at the Spring 1993 APS meeting, the Summer conferences, and at the Fall 1993 pp symposium in Tsukuba. Several papers (See Attached [LeptoQuark PRL, RapGap PRL, Top PRL]) have appeared in print, a lepto-quark search, a rapidity-gap study, and. a lower mass limit on the Standard Model top quark where we also present a spectacular event that has laxge $y, a high energy electron and a high momentum muon, both isolated, and two sizable jets. When interpreted as a it event, a top mass around 145 GeV (with a large 30 GeV error) is obtained.
    ; I~CN of TH;3 DOCUMENT 18 Unlfmfts DISCLAIMER" class="panel-rg color-a">[Show full text]
  • Future Hadron Physics at Fermilab
    Future Hadron Physics at Fermilab Jeffrey A. Appel Fermi National Accelerator Laboratory PO Box 500, Batavia, IL 60510 USA [email protected] Abstract. Today, hadron physics research occurs at Fermilab as parts of broader experimental programs. This is very likely to be the case in the future. Thus, much of this presentation focuses on our vision of that future – a future aimed at making Fermilab the host laboratory for the International Linear Collider (ILC). Given the uncertainties associated with the ILC - the level of needed R&D, the ILC costs, and the timing - Fermilab is also preparing for other program choices. I will describe these latter efforts, efforts focused on a Proton Driver to increase the numbers of protons available for experiments. As examples of the hadron physics which will be coming from Fermilab, I summarize three experiments: MIPP/E907 which is running currently, and MINERνA and Drell-Yan/E906 which are scheduled for future running periods. Hadron physics coming from the Tevatron Collider program will be summarized by Arthur Maciel in another talk at Hadron05. Keywords: Fermilab, Tevatron, ILC, hadron, MIPP, MINERνA, Drell-Yan, proton driver. PACS: 13.85.-t INTRODUCTION In order to envisage the future of hadron physics at Fermilab, it will be useful to know the research context at the Laboratory. That can be best done by looking at the recent presentations by Fermilab's new Director, Piermaria Oddone, who began his tenure as Director on July 1, 2005. Pier has had several opportunities to project the vision of Fermilab's future, both inside the Laboratory and to outside committees.1 I draw heavily on his presentations.
    [Show full text]
  • Status of New Physics Searches at the Tevatron
    DIS 2011 Newport News, VA Status of New Physics Searches at the Tevatron Craig Group (University of Virginia and Fermilab) on behalf of the CDF and D0 experiments… Outline Searches at the Tevatron • The Tevatron, CDF, and D0 • Dilepton/diphoton resonances • Diboson resonances • Complex final states (MET, jets, H.F.) • Higgs (SM) • Higgs (non‐SM) DIS2011 C. Group ‐ Review of Searches at the Tevatron 2 The Tevatron at Fermilab The Tevatron currently provides the high energy proton‐anproton collisions: Ecm = 1.96 TeV CDF DO Tevatron DIS2011 C. Group ‐ Review of Searches at the Tevatron 3 The Tevatron is… …and has been a Discovery Machine! Results shown today include 4‐8 ‐1 Single Top Rare Bs decays Diboson Channels Y(4140) Bs ΦΦ Charm mixing ZZ WZ Z+b Bs‐mixing Exclusive charm Exclusive ee Top Quark DIS2011 C. Group ‐ Review of Searches at the Tevatron 4 Dilepton Final States Old‐fashioned bump hunt in Mee distribuon: CDF: 5.7‐1 ‐Z producon and decay into ee/µµ precisely measured D0: 5.4‐1 ‐Lepton ID/Reco and Trigger efficiencies high and very well understood ‐Background low and easily determined (QCD fakes) ‐Clean events PLB 695, 88 (2011) CDF Public Note 10405 DIS2011 C. Group ‐ Review of Searches at the Tevatron 5 Dilepton Final States Old‐fashioned bump hunt in Mee distribuon: CDF: 5.7‐1 ‐Z producon and decay into ee/µµ precisely measured 2 D0: 5.4‐1 ‐Lepton ID/Reco and Trigger efficiencies high and very well understood = 960 GeV/c ‐Background low and easily determined (QCD fakes) Mee ‐Clean events PLB 695, 88 (2011) CDF Public Note 10405 event ever recorded! dilepton the highest DIS2011 C.
    [Show full text]
  • Physicists Raid Tevatron for Parts Fermilab Icon Plundered Amid Tight Budgets and Shifting Scientific Aims
    IN FOCUS NEWS HIGH-ENERGY PHYSICS Physicists raid Tevatron for parts Fermilab icon plundered amid tight budgets and shifting scientific aims. BY EUGENIE SAMUEL REICH CANNIBALIZING THE TEVATRON Parts at the Tevatron and its two main experiments, the CDF and D0, are being t is a 4,000-tonne edifice that stands three considered for recycling in the wake of the collider’s closure in September 2011. stories high, chock full of particle detectors, Antiproton power supplies, electronics and photo­ source Imultiplier tubes, all layered like a giant onion Possibly open around a cylindrical magnet. During 26 years Booster of operation at the Fermi National Accelerator to visitors Laboratory in Batavia, Illinois, this behemoth, Main injector the Collider Detector at Fermilab (CDF), and recycler helped to find the top quark and chased the • Photomultiplier tubes for Higgs boson. But since the lab’s flagship parti- nuclear-structure experiment CDF cle collider, the Tevatron, was switched off in • Electronics for the Large September 2011, the detector has been surplus Hadron Collider in Europe • Central magnet for a stock — and it is now slowly being cannibal- possible particle-decay ized for parts. Beams repurposed experiment When the Tevatron closed, Fermilab for neutrino and • Possible educational display announced that the CDF would become an other experiments educational display. Along with its companion experiment, D0, the detector was supposed to form the centre­piece of a tour through simu- Tevatron lated control rooms and decommissioned Possible educational display accelerator tunnels. But tight budgets for experimental particle physicists — combined 500 m with their tendency to tinker and recycle — are pushing the outcome in a different direction, D0 at least for the CDF.
    [Show full text]
  • Tevatron Runii Performance and Plans
    Proceedings of EPAC 2002, Paris, France TEVATRON RUN II PERFORMANCE AND PLANS M. Church†, FNAL*, Batavia, IL 60510, USA Abstract The Fermilab accelerator complex has been operating 2 CURRENT STATUS AND ISSUES Run II for approximately one year. In this mode 36 Table 1 lists the current status of important Collider proton bunches collide with 36 antiproton bunches at 2 parameters along with the Run IIa goals for 2002. interaction regions in the Tevatron at 980 GeV beam energy. The long range goal in Run II is to obtain a total Table 1: Important Run IIa parameters. Column 2 shows -1 best values on 1/1/2002, column 3 shows best values on integrated luminosity of 15 pb . The current status and performance of the accelerator complex is described, 5/25/2002, and column 4 shows goals for 1/1/2003 including the Tevatron, Main Injector, Antiproton Source, Parameter 1/1/02 5/25/02 1/1/03 and Recycler Ring. Future upgrade plans and prospects goal for reaching the admittedly ambitious long range goal are presented. antiproton production 10 11 18 rate (E10/hr) 1 COLLIDER OPERATIONS AT Accumulator core size 115 120 165 FERMILAB (E10) There are 2 basic modes during Collider operation: antiproton transfer .23 .37 .80 antiproton stacking and "shots." A shot is the process of efficiency loading the Tevatron with protons and antiprotons. In stacking mode, a batch of 84 53MHz proton antiprotons/bunch @ 7.6 10.8 33 bunches is extracted from the Booster Ring at 8 GeV and low beta (E9) injected into the MI (Main Injector) every 2.2 seconds.
    [Show full text]
  • Arxiv:1005.3797V2 [Hep-Ph]
    FERMILAB-PUB-10-143-T The Tevatron at the Frontier of Dark Matter Direct Detection Yang Bai, Patrick J. Fox and Roni Harnik Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510, USA Abstract Direct detection of dark matter (DM) requires an interaction of dark matter particles with nucleons. The same interaction can lead to dark matter pair production at a hadron collider, and with the addition of initial state radiation this may lead to mono-jet signals. Mono-jet searches at the Tevatron can thus place limits on DM direct detection rates. We study these bounds both in the case where there is a contact interaction between DM and the standard model and where there is a mediator kinematically accessible at the Tevatron. We find that in many cases the Tevatron provides the current best limit, particularly for light dark matter, below 5 GeV, a and for spin dependent interactions. Non-standard dark matter candidates are also constrained.∼ The introduction of a light mediator significantly weakens the collider bound. A direct detection discovery that is in apparent conflict with mono-jet limits will thus point to a new light state coupling the standard model to the dark sector. Mono-jet searches with more luminosity and including the spectrum shape in the analysis can improve the constraints on DM-nucleon scattering cross section. arXiv:1005.3797v2 [hep-ph] 24 Dec 2010 1 Introduction From astronomical and cosmological observations it is now clear that 25% of the matter-energy ∼ content of the universe if made up by dark matter (DM).
    [Show full text]