Anatomy of Top-Mode Extended Technicolor Model
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Search for Exotics with Top at ATLAS
Search for exotics with top at ATLAS Diedi Hu Columbia University On behalf of the ATLAS collaboration EPSHEP2013, Stockholm July 18, 2013 Motivation Motivation Due to its large mass, top quark offers a unique window to search for new physics: mt ∼ ΛEWSB (246GeV): top may play a special role in the EWSB Many extensions of the SM explain the large top mass by allowing the top to participate in new dynamics. Approaches of new physics search Measure top quark properties: check with SM prediction. Directly search for new particles coupling to top tt resonances searches Search for anomalous single top production Vector-like quarks searches (Covered in another talk "Searches for fourth generation vector-like quarks with the ATLAS detector") Search for exotics with tt and single top D.Hu, Columbia Univ. 2 / 16 tt resonance search with 14.3 fb−1 @ 8TeV tt resonance: benchmark models 2 specific models used as examples of sensitivity Leptophobic topcolor Z 0 [2] Explains the top quark mass and EWSB through top quark condensate Z 0 couples strongly only to the first and third generation of quarks Narrow resonance: Γ=m 1:2% ∼ Kaluza-Klein gluons [3] Predicted by the Bulk Randall-Sundrum models with warped extra dimension Strongly coupled to the top quark Broad resonance: Γ=m 15% ∼ Search for exotics with tt and single top D.Hu, Columbia Univ. 3 / 16 tt resonance search with 14.3 fb−1 @ 8TeV tt resonance: lepton+jets(I) [4] Backgrounds SM tt, Z+jets, single top, diboson and W+jets shape: directly from MC W+jets normalization, multijet: estimated from data Event selection One top decays hadronically and The boosted selection the other semileptonically. -
``Topcolor''; Invited Talk Presented At" Strongly Coupled Gauge Theories
FERMILAB-Conf-97/032-T TOPCOLOR1 CHRISTOPHER T. HILL Fermi National Accelerator Laboratory P.O. Box 500, Batavia, Illinois, 60510, USA We review a class of dynamical models in which top condensation occurs at the weak scale, giving rise to the large top quark mass and other phenomena. This typically requires a color embedding, SU(3) SU(3)1 SU(3)2, ergo “Topcolor.” Topcolor suggests c → × a novel route to technicolor models in which sequential quarks condense under the Topcolor interaction to break electroweak symmetries. 1 Top Quark Condensation 1.1 Preliminary The top quark has arrived with a mass of 175 GeV. This is remarkably ∼ large in comparison to all other known fundamental particles, and coin- cidently equals the natural scale of electroweak interactions, 1/ 2√2GF . The top quark mass may be dynamically generated, analogousq to a con- stituent quark mass in QCD. Then the relevant question becomes: “Are arXiv:hep-ph/9702320v1 12 Feb 1997 there new strong interactions that are revealing themselves through the large top mass?” If the answer is no, then the most sensible scenario for physics beyond the standard model is something like the minimal supersymmetric standard model (MSSM). In this case the top quark mass is given by the infra–red renormalization group fixed point [1], and many of the successful predictions of unification are tied to this fact [2]. By itself, this is remarkable, because the infra–red renormalization group fixed point is really a consequence of the approximate scale invariance of the unified theory over the range of 1Invited Talk presented at Strongly Coupled Gauge Theories ‘96, Nagoya, Nov. -
Two Composite Higgs Doublets: Is It the Low Energy Limit of A
Two Composite Higgs Doublets: Is it the Low Energy Limit of a Natural Strong Electroweak Symmetry Breaking Sector ? Alfonso R. Zerwekh∗ Centro de Estudios Subat´omicos and Instituto de F´ısica, Facultad de Ciencias, Universidad Austral de Chile, Casilla 567, Valdivia,Chile Abstract In this paper, we propose an effective model scheme that describes the electroweak symmetry breaking sector by means of composite Higgs- like scalars, following the ideas of Minimal Walking Technicolor (MWT). We argue that, because of the general failure of Extended Technicolor (ETC) to explain the mass of the top quark, it is necessary to introduce two composite Higgs bosons: one of them originated by a MWT-ETC sector and the other one produced by a Topcolor sector. We focus on the phenomenological differences between the light composite Higgs present in our model and the fundamental Higgs boson predicted by the Standard Model and their production at the LHC. We show that in this scheme the main production channel of the lighter Higgs boson are the associated production with a gauge boson and WW fusion but not the gluon-gluon fusion channel which is substantially suppressed. 1 Introduction arXiv:0907.4690v3 [hep-ph] 25 Dec 2009 High Energy Physics is at the dawn of a new era. In the very near future the LHC will allow us to explore, for the first time, the physics responsible for the electroweak symmetry breaking. We are quite sure that something different to the minimal Higgs sector of the Standard Model will be found, but the conjectured alternatives, far from being unique, are varied and very different among them, going from Higgsless models to Supersymmetry. -
Higgs Bosons Strongly Coupled to the Top Quark
CERN-TH/97-331 SLAC-PUB-7703 hep-ph/9711410 November 1997 Higgs Bosons Strongly Coupled to the Top Quark Michael Spiraa and James D. Wellsb aCERN, Theory Division, CH-1211 Geneva, Switzerland bStanford Linear Accelerator Center Stanford University, Stanford, CA 94309† Abstract Several extensions of the Standard Model require the burden of electroweak sym- metry breaking to be shared by multiple states or sectors. This leads to the possibility of the top quark interacting with a scalar more strongly than it does with the Stan- dard Model Higgs boson. In top-quark condensation this possibility is natural. We also discuss how this might be realized in supersymmetric theories. The properties of a strongly coupled Higgs boson in top-quark condensation and supersymmetry are described. We comment on the difficulties of seeing such a state at the Tevatron and LEPII, and study the dramatic signatures it could produce at the LHC. The four top quark signature is especially useful in the search for a strongly coupled Higgs boson. We also calculate the rates of the more conventional Higgs boson signatures at the LHC, including the two photon and four lepton signals, and compare them to expectations in the Standard Model. CERN-TH/97-331 SLAC-PUB-7703 hep-ph/9711410 November 1997 †Work supported by the Department of Energy under contract DE-AC03-76SF00515. 1 Introduction Electroweak symmetry breaking and fermion mass generation are both not understood. The Standard Model (SM) with one Higgs scalar doublet is the simplest mechanism one can envision. The strongest arguments in support of the Standard Model Higgs mechanism is that no experiment presently refutes it, and that it allows both fermion masses and electroweak symmetry breaking. -
Model-Independent Constraints on Topcolor from Rb
MADPH-97-984 TUM-HEP-267/97 hep-ph/9702265 Model-independent Constraints on Topcolor from Rb Gustavo Burdman∗ Department of Physics, University of Wisconsin, Madison, WI 53706, USA and Dimitris Kominis† Institut f¨ur Theoretische Physik, Technische Universit¨at M¨unchen, James-Franck-Straße, 85748 Garching, Germany Abstract arXiv:hep-ph/9702265v2 8 May 1997 We identify and compute the main corrections to Rb in Topcolor theories. They are due to the top-pions, the pseudo-Goldstone bosons associated with the chiral symmetry breaking responsible for the top quark mass, and amount to (1 4)%, − − independent of the details of the Topcolor model. We show that the cancellation of this effect against the contributions from Topcolor vector and scalar resonances is unlikely, given the inherently distinct character of the two scales governing the potentially cancelling terms. The resulting value of Rb leads to severe constraints on Topcolor theories. ∗e-mail address: [email protected] †e-mail address: [email protected] 1 Introduction The large value of the top-quark mass has led to speculation that the properties of the top quark may be fundamentally different from those of the other known fermions. In theories of top condensation, for example, a new strong gauge interaction (Topcolor), which couples to the t-quark and perhaps to other fermions as well, drives the formation of a tt¯ condensate and imparts a large dynamical mass to the top quark. In the process, h i the chiral symmetries associated with the strongly interacting fermions are spontaneously broken and at least three Goldstone bosons emerge. -
The Higgs Boson in the Periodic System of Elementary Particles
Southern Adventist University KnowledgeExchange@Southern Faculty Works Physics and Engineering Department 3-2013 The iH ggs Boson in the Periodic System of Elementary Particles Ding-Yu Chung Ray Hefferlin Follow this and additional works at: https://knowledge.e.southern.edu/facworks_physics Part of the Elementary Particles and Fields and String Theory Commons Recommended Citation Chung, Ding-Yu and Hefferlin, Ray, "The iH ggs Boson in the Periodic System of Elementary Particles" (2013). Faculty Works. 12. https://knowledge.e.southern.edu/facworks_physics/12 This Article is brought to you for free and open access by the Physics and Engineering Department at KnowledgeExchange@Southern. It has been accepted for inclusion in Faculty Works by an authorized administrator of KnowledgeExchange@Southern. For more information, please contact [email protected]. Journal of Modern Physics, 2013, 4, 21-26 doi:10.4236/jmp.2013.44A004 Published Online April 2013 (http://www.scirp.org/journal/jmp) The Higgs Boson in the Periodic System of Elementary Particles Ding-Yu Chung1, Ray Hefferlin2 1Utica, Michigan, USA 2Department of Physics, Southern Adventist University, Collegedale, USA Email: [email protected], [email protected] Received February 12, 2013; revised March 15, 2013; accepted March 27, 2013 Copyright © 2013 Ding-Yu Chung, Ray Hefferlin. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. ABSTRACT It is proposed that the observed Higgs Boson at the LHC is the Standard Model Higgs boson that adopts the existence of the hidden lepton condensate. The hidden lepton is in the forbidden lepton family, outside of the three lepton families of the Standard Model. -
Outlook Post-Higgs
Outlook Post-Higgs Christopher T. Hill Fermilab UCLA Higgs Workshop March 22, 2013 A dynamical “Higgs” mechanism was supposed to explain the origin of electroweak mass A dynamical “Higgs” mechanism was supposed to explain the origin of electroweak mass We now know that, evidently, a fundamental Higgs Boson exists and explains the masses of quarks, leptons, W and Z A dynamical “Higgs” mechanism was supposed to explain the origin of electroweak mass We now know that, evidently, a fundamental Higgs Boson exists and explains the masses of quarks, leptons, W and Z The Higgs Boson does NOT explain the origin of the electroweak mass-scale A dynamical “Higgs” mechanism was supposed to explain the origin of electroweak mass We now know that, evidently, a fundamental Higgs Boson exists and explains the masses of quarks, leptons, W and Z The Higgs Boson does NOT explain the origin of the electroweak mass-scale i.e., what is the origin of the Higgs Boson mass itself? A dynamical “Higgs” mechanism was supposed to explain the origin of electroweak mass We now know that, evidently, a fundamental Higgs Boson exists and explains the masses of quarks, leptons, W and Z The Higgs Boson does NOT explain the origin of the electroweak mass-scale i.e., what is the origin of the Higgs Boson mass itself? This may present opportunities for a deeper understanding QCD beautifully explains the origin of strong mass : The magnificent scale anomaly: The scale current: = 0 in a scale invariant theory The magnificent scale anomaly: The scale current: = 0 in a scale invariant -
Single Top Production Associated with a Neutral Scalar at LHC in Topcolor-Assisted Technicolor
Chinese Physics C (HEP & NP) Vol. 32, No. 9, Sep., 2008 Single top production associated with a neutral scalar at LHC in topcolor-assisted technicolor LIU Guo-Li(7Iw)1 ZHANG Huan-Jun(Ü)2;1) 1 (Department of Physics, Zhengzhou University, Henan 450052, China) 2 (Department of Physics, Henan Normal University, Xinxiang 453007, China) Abstract The topcolor-assisted technicolor (TC2) model predicts a number of neutral scalars like the top-pion 0 0 (πt ) and the top-Higgs (ht ). These scalars have flavor-changing neutral-current (FCNC) top quark couplings, among which the top-charm transition couplings may be sizable. Such FCNC couplings induce single top productions associated with a neutral scalar at the CERN Large Hadron Collider (LHC) through the parton ! 0 ! 0 processes cg tπt and cg tht . In this paper we examine these productions and find their production rates can exceed the 3σ sensitivity of the LHC in a large part of parameter space. Since in the Standard Model and the minimal supersymmetric model such rare productions have unobservably small production rates at the LHC, these rare processes will serve as a good probe for the TC2 model. Key words top quark, technicolor, LHC PACS 14.65.Ha, 12.60.Fr, 12.60.Jv As the heaviest fermion in the Standard Model ated with a neutral scalar at the LHC through the 0 0 (SM), the top quark may be a sensitive probe of new parton processes cg tπt and cg tht . In this pa- [1] ! ! physics . So far there remain plenty of room for new per we examine these productions and figure out if physics in top quark sector due to the small statis- their rates can exceed the 3σ sensitivity of the LHC. -
Symmetry Breaking and Generational Mixing in Topcolor--Assisted
BUHEP–96–2 hep-ph/9602221 Symmetry Breaking and Generational Mixing in Topcolor–Assisted Technicolor Kenneth Lane† Department of Physics, Boston University 590 Commonwealth Avenue, Boston, MA 02215 Abstract Topcolor–assisted technicolor provides a dynamical explanation for electroweak and flavor symmetry breaking and for the large mass of the top quark without unnatural fine tuning. A major challenge is to generate the observed mixing between heavy and light generations while breaking the strong topcolor interactions near 1 TeV. I argue that these phenomena, as well as electroweak symmetry breaking, are intimately connected and I arXiv:hep-ph/9602221v1 4 Feb 1996 present a scenario for them based on nontrivial patterns of technifermion condensation. I also exhibit a class of models realizing this scenario. This picture leads to a rich phe- nomenology, especially in hadron and lepton collider experiments in the few hundred GeV to few TeV region and in precision electroweak tests at the Z0, atomic parity violation, and polarized Møller scattering. 2/96 † [email protected] 1. Introduction Topcolor–assisted technicolor (TC2) was proposed by Hill [1] to overcome major shortcomings of top–condensate models of electroweak symmetry breaking [2], [3] and of technicolor models of dynamical electroweak and flavor symmetry breaking [4], [5]. Technicolor and extended technicolor (ETC) have been unable to provide a natural and plausible understanding of why the top quark mass is so large [6]. On the other hand, models in which strong topcolor interactions drive top–quark condensation and elec- troweak symmetry breaking are unnatural. To reproduce the one–Higgs–doublet standard model consistent with precision electroweak measurements (especially of the parameter 2 2 2 ρ = M /M cos θW 1), the topcolor energy scale must be much greater than the W Z ≃ electroweak scale of (1 TeV). -
Search for Top Quark Pair Resonances with the CMS Detector at the LHC
Search for Top Quark Pair Resonances with the CMS Detector at the LHC Von der Fakult¨atf¨urMathematik, Informatik und Naturwissenschaften der RWTH Aachen University zur Erlangung des akademischen Grades eines Doktors der Naturwissenschaften genehmigte Dissertation vorgelegt von Wael Haj Ahmad aus Edlib/Syrien Berichter: Univ.-Prof. Dr.rer.nat. Achim Stahl Univ.-Prof. Dr.rer.nat. Thomas Hebbeker Tag der m¨undlichen Pr¨ufung:29.05.2013 Diese Dissertation ist auf den Internetseiten der Hochschulbibliothek online verf¨ugbar. Contents Contents vi Abstract vii Zusammenfassung ix 1 Overview 1 1.1 Introduction . .1 1.2 The Standard Model of Particle Physics (SM) . .2 1.3 The Top Quark . .4 1.3.1 Top Quark Pair Production . .4 1.3.2 Top Quark Decay Channels . .7 1.4 Top Quark Pair Resonances . .8 1.4.1 Topcolor Assisted Technicolor Z0 ............9 2 The CMS Detector at the LHC 13 2.1 The Large Hadron Collider . 13 2.2 The CMS Detector . 17 2.2.1 The CMS Requirements . 18 2.2.2 The CMS Coordinates . 20 2.2.3 The CMS Inner Tracking System . 21 2.2.4 The Electromagnetic Calorimeter . 22 iv CONTENTS 2.2.5 The Hadronic Calorimeter . 24 2.2.6 The Superconducting Magnet . 26 2.2.7 The Muon System . 26 2.2.8 The Trigger System . 28 3 Object Identification and Reconstruction 31 3.1 Reconstruction of Tracks . 32 3.2 Reconstruction of Primary Vertices . 35 3.3 Reconstruction and Identification of Muons . 37 3.3.1 Reconstruction of Muons . 37 3.4 Reconstruction of Electrons . -
Search for Pair-Produced Vectorlike B Quarks in Proton-Proton
EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH (CERN) CERN-PH-EP/2015-170 2018/09/21 CMS-B2G-13-006 Search for pair-produced vectorlikep B quarks in proton-proton collisions at s = 8 TeV The CMS Collaboration∗ Abstract A search for the production of a heavy B quark, having electric charge −1/3 and vec- tor couplings to W, Z, and H bosons, is carried out using proton-proton collision data recorded at the CERN LHC by the CMS experiment, corresponding to an integrated luminosity of 19.7 fb−1. The B quark is assumed to be pair produced and to decay in one of three ways: to tW, bZ, or bH. The search is carried out in final states with one, two, and more than two charged leptons, as well as in fully hadronic final states. Each of the channels in the exclusive final-state topologies is designed to be sensitive to specific combinations of the B quark-antiquark pair decays. The observed event yields are found to be consistent with the standard model expectations in all the fi- nal states studied. A statistical combination of these results is performed, and upper limits are set on the cross section of the strongly produced B quark-antiquark pairs as a function of the B quark mass. Lower limits on the B quark mass between 740 and 900 GeV are set at a 95% confidence level, depending on the values of the branching fractions of the B quark to tW, bZ, and bH. Overall, these limits are the most stringent to date. -
Probing Topcolor-Assisted Technicolor from Top-Charm Associated Production at LHC
Probing Topcolor-Assisted Technicolor from Top-Charm Associated Production at LHC Junjie Caoa;b, Zhaohua Xiong c, Jin Min Yang b a CCAST (World Laboratory), P.O.Box 8730, Beijing 100080, China b Institute of Theoretical Physics, Academia Sinica, Beijing 100080, China c Graduate School of Science, Hiroshima University, Hiroshima 937-6256, Japan (April 2, 2003) tc bb + +√2KUR∗ KDLc¯RbLπt + h:c: ; (1) We propose to probe the topcolor-assisted technicolor i (TC2) model from the top-charm associated productions at where v 174 GeV, F 50 GeV is the top-pion decay the LHC, which are highly suppressed in the Standard Model. t constant' and the factor' v2 F 2=v reflects the effect Due to the flavor-changing couplings of the top quark with − t the scalars (top-pions and top-Higgs) in TC2 model, the of the mixing between thep top-pions and the would-be top-charm associated productions can occur via both the s- goldstone bosons [8]. KUL, KDL and KUR are the rota- channel and t-channel parton processes by exchanging a scalar tion matrices that transform the weak eigenstates of left- field at the LHC. We examined these processes through Monte handed up-type, down-type and right-handed up-type Carlo simulation and found that they can reach the observ- quarks to the mass eigenstates, respectively. As pointed able level at the LHC in quite a large part of the parameter tc out in [6], the transition between tR and cR, KUR,canbe space of the TC2 model. naturally around 10% 30% without conflict with low energy experimental data∼ and Ks can be parameterized 14.65.Ha, 12.60.Fr, 12.60.Jv as follows: Ktt = Kbb =1;Ktt =1 , The fancy idea of technicolor (TC) provides a possi- UL DL DR − ble mechanism of breaking the electroweak symmetry dy- tc tt 2 tu 2 2 KUR = 1 KUR KUR 2 ; (2) namically.