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Title: LHC signals from cascade decays of warped vector resonances

Abstract

Recently (arXiv:1608.00526), a new framework for warped higher-dimensional compactifications with “bulk” standard model (SM) was proposed: in addition to the UV (Planck scale) and IR (a couple of TeV) branes, there is an intermediate brane, taken to be around 10TeV. The SM matter and Higgs fields propagate from the UV brane down to this intermediate brane only, while gauge and gravity fields propagate in the entire bulk. Such a configuration renders the lightest gauge Kaluza-Klein (KK) states within LHC reach, simultaneously satisfying flavor and CP constraints. In addition, the usual leading decay modes of the lightest KK gauge bosons into top and Higgs bosons are suppressed. This effect permits erstwhile subdominant channels to become significant. These include flavor-universal decays to SM fermions and Higgs bosons, and a novel channel — decay to a radion and a SM gauge boson, followed by radion decay to a pair of SM gauge bosons. In this work, we first delineate the parameter space where the above mentioned cascade decay of gauge KK particles dominates, and thereby can be the discovery mode at the LHC. We then perform a detailed analysis of the LHC signals from this model, finding that 300/fb suffices for evidence ofmore » KK-gluon in tri-jet, jet + di-photon and jet + di-boson channels. However, KK photon in photon + di-jet, and KK-W in leptonic W + di-jet require 3000/fb. The crucial feature of this decay chain is a “double” resonance, i.e. 3-particle and 2-particle invariant mass peaks, corresponding to the KK gauge boson and the radion respectively.« less

Authors:
 [1];  [2];  [1];  [1];  [3];  [1]
  1. Univ. of Maryland, College Park, MD (United States). Maryland Center for Fundamental Physics. Dept. of Physics
  2. Univ. of Maryland, College Park, MD (United States). Maryland Center for Fundamental Physics. Dept. of Physics; Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Physics and Astronomy
  3. Univ. of Florida, Gainesville, FL (United States). Dept. of Physics; European Organization for Nuclear Research (CERN), Geneva (Switzerland). Theory Division
Publication Date:
Research Org.:
Univ. of Florida, Gainesville, FL (United States); Univ. of Maryland, College Park, MD (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25); National Science Foundation (NSF); Korean Research Foundation (KRF)
OSTI Identifier:
1424609
Grant/Contract Number:
SC0010296; PHY-1315155
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of High Energy Physics (Online)
Additional Journal Information:
Journal Name: Journal of High Energy Physics (Online); Journal Volume: 2017; Journal Issue: 5; Journal ID: ISSN 1029-8479
Publisher:
Springer Berlin
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; phenomenological models; phenomenology of field theories in higher dimensions

Citation Formats

Agashe, Kaustubh S., Collins, Jack H., Du, Peizhi, Hong, Sungwoo, Kim, Doojin, and Mishra, Rashmish K. LHC signals from cascade decays of warped vector resonances. United States: N. p., 2017. Web. doi:10.1007/JHEP05(2017)078.
Agashe, Kaustubh S., Collins, Jack H., Du, Peizhi, Hong, Sungwoo, Kim, Doojin, & Mishra, Rashmish K. LHC signals from cascade decays of warped vector resonances. United States. doi:10.1007/JHEP05(2017)078.
Agashe, Kaustubh S., Collins, Jack H., Du, Peizhi, Hong, Sungwoo, Kim, Doojin, and Mishra, Rashmish K. Mon . "LHC signals from cascade decays of warped vector resonances". United States. doi:10.1007/JHEP05(2017)078. https://www.osti.gov/servlets/purl/1424609.
@article{osti_1424609,
title = {LHC signals from cascade decays of warped vector resonances},
author = {Agashe, Kaustubh S. and Collins, Jack H. and Du, Peizhi and Hong, Sungwoo and Kim, Doojin and Mishra, Rashmish K.},
abstractNote = {Recently (arXiv:1608.00526), a new framework for warped higher-dimensional compactifications with “bulk” standard model (SM) was proposed: in addition to the UV (Planck scale) and IR (a couple of TeV) branes, there is an intermediate brane, taken to be around 10TeV. The SM matter and Higgs fields propagate from the UV brane down to this intermediate brane only, while gauge and gravity fields propagate in the entire bulk. Such a configuration renders the lightest gauge Kaluza-Klein (KK) states within LHC reach, simultaneously satisfying flavor and CP constraints. In addition, the usual leading decay modes of the lightest KK gauge bosons into top and Higgs bosons are suppressed. This effect permits erstwhile subdominant channels to become significant. These include flavor-universal decays to SM fermions and Higgs bosons, and a novel channel — decay to a radion and a SM gauge boson, followed by radion decay to a pair of SM gauge bosons. In this work, we first delineate the parameter space where the above mentioned cascade decay of gauge KK particles dominates, and thereby can be the discovery mode at the LHC. We then perform a detailed analysis of the LHC signals from this model, finding that 300/fb suffices for evidence of KK-gluon in tri-jet, jet + di-photon and jet + di-boson channels. However, KK photon in photon + di-jet, and KK-W in leptonic W + di-jet require 3000/fb. The crucial feature of this decay chain is a “double” resonance, i.e. 3-particle and 2-particle invariant mass peaks, corresponding to the KK gauge boson and the radion respectively.},
doi = {10.1007/JHEP05(2017)078},
journal = {Journal of High Energy Physics (Online)},
number = 5,
volume = 2017,
place = {United States},
year = {Mon May 15 00:00:00 EDT 2017},
month = {Mon May 15 00:00:00 EDT 2017}
}

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  • We study production of Kaluza-Klein gluons (KKG) at the Large Hadron Collider (LHC) in the framework of a warped extra dimension with the Standard Model (SM) fields propagating in the bulk. We show that the detection of KK gluon is challenging since its production is suppressed by small couplings to the proton's constituents. Moreover, the KK gluon decaysmostly to top pairs due to an enhanced coupling and hence is broad. Nevertheless, we demonstrate that for MKKG<~;; 4 TeV, 100 fb-1 of data at the LHC can provide discovery of the KK gluon. We utilize a sizeable left-right polarization asymmetry frommore » the KK gluon resonance to maximize the signal significance, and we explore the novel feature of extremely highly energetic"top-jets." We briefly discuss how the detection of electroweak gauge KK states (Z/W) faces a similar challenge since their leptonic decays ("golden" modes) are suppressed. Our analysis suggests that other frameworks, for example little Higgs, which rely on UV completion via strong dynamics might face similar challenges, namely (1) Suppressed production rates for the new particles (such as Z'), due to their"lightfermion-phobic" nature, and (2) Difficulties in detection since the new particles are broad and decay predominantly to third generation quarks and longitudinal gauge bosons.« less
  • We study production of Kaluza-Klein (KK) gluons at the Large Hadron Collider (LHC) in the framework of a warped extra dimension with the standard model fields propagating in the bulk. We show that the detection of the KK gluon is challenging since its production is suppressed by small couplings to the proton's constituents. Moreover, the KK gluon decays mostly to top pairs due to an enhanced coupling and hence is broad. Nevertheless, we demonstrate that for M{sub KKG} < or approx. 4 TeV, 100 fb{sup -1} of data at the LHC can provide discovery of the KK gluon. We utilizemore » a sizable left-right polarization asymmetry from the KK gluon resonance to maximize the signal significance, and we explore the novel feature of extremely highly energetic 'top-jets'. We briefly discuss how the detection of electroweak gauge KK states (Z/W) faces a similar challenge since their leptonic decays (golden modes) are suppressed. Our analysis suggests that other frameworks, for example, little Higgs, which rely on UV completion via strong dynamics might face similar challenges, namely, (1) suppressed production rates for the new particles (such as Z{sup '}), due to their 'light-fermion-phobic' nature, and (2) difficulties in detection since the new particles are broad and decay predominantly to third generation quarks and longitudinal gauge bosons.« less
  • We study signals at the Large Hadron Collider (LHC) for Kaluza-Klein (KK) excitations of the electroweak gauge bosons in the framework with the standard model (SM) gauge and fermion fields propagating in a warped extra dimension. Such a framework addresses both the Planck-weak and flavor hierarchy problems of the SM. Unlike the often studied Z{sup '} cases, in this framework, there are three neutral gauge bosons due to the underlying SU(2){sub L}xSU(2){sub R}xU(1){sub X} gauge group in the bulk. Furthermore, couplings of these KK states to light quarks and leptons are suppressed, whereas those to top and bottom quarks aremore » enhanced compared to the SM gauge couplings. Therefore, the production of light quark and lepton states is suppressed relative to other beyond the SM constructions, and the fermionic decays of these states are dominated by the top and bottom quarks, which are, though, overwhelmed by KK gluons dominantly decaying into them. However, as we emphasize in this paper, decays of these states to longitudinal W, Z and Higgs are also enhanced similarly to the case of top and bottom quarks. We show that the W, Z and Higgs final states can give significant sensitivity at the LHC to {approx}2(3) TeV KK scale with an integrated luminosity of {approx}100 fb{sup -1} ({approx}1 ab{sup -1}). Since current theoretical framework(s) favor KK masses > or approx. 3 TeV, a luminosity upgrade of LHC is likely to be crucial in observing these states.« less
  • We study signals at the LHC for the Kaluza-Klein (KK) excitations of electroweak charged gauge bosons in the framework of the standard model (SM) fields propagating in the bulk of a warped extra dimension. Such a scenario can solve both the Planck-weak and flavor hierarchy problems of the SM. There are two such charged states in this scenario with couplings to light quarks and leptons being suppressed relative to those in the SM, whereas the couplings to top/bottom quarks are enhanced, similar to the case of electroweak neutral gauge bosons previously studied. However, unlike the case of electroweak neutral gaugemore » bosons, there is no irreducible QCD background (including pollution from possibly degenerate KK gluons) for decays to top+bottom final states so that this channel is useful for the discovery of the charged states. Moreover, decays of electroweak charged gauge bosons to longitudinal W, Z and Higgs are enhanced just as for the neutral bosons. However, unlike for the neutral gauge bosons, the purely leptonic (and hence clean) decay mode of the WZ is fully reconstructible so that the ratio of the signal to the SM (electroweak) background can potentially be enhanced by restricting to the resonance region more efficiently. We show that such final states can give sensitivity to 2(3) TeV masses with an integrated luminosity of 100(300) fb{sup -1}. We emphasize that improvements in discriminating a QCD jet from a highly boosted hadronically decaying W, and a highly boosted top jet from a bottom jet will enhance the reach for these KK particles, and that the signals we study for the warped extra dimensional model might actually be applicable also to a wider class of nonsupersymmetric models of electroweak symmetry breaking.« less
  • The framework of a warped extra dimension with the standard model (SM) fields propagating in it is a very well-motivated extension of the SM since it can address both the Planck-weak and flavor hierarchy problems of the SM. Within this framework, solution to the little hierarchy problem motivates extending the SM electroweak (EW) 5D gauge symmetry in such a way that its breakdown to the SM delivers the SM Higgs boson. We study signals at the large hadron collider (LHC) for the extra EW (called coset) gauge bosons, a fundamental ingredient of this framework. The coset gauge bosons, due tomore » their unique EW gauge quantum numbers [doublets of SU(2){sub L}], do not couple at leading order to two SM particles. We find that, using the associated production of the charged coset gauge bosons via their coupling to bottom quark and a (light) Kaluza-Klein excitation of the top quark, the LHC can have a 3{sigma} reach of {approx}2(2.6) TeV for the coset gauge boson masses with {approx}100(1000) fb{sup -1} luminosity. Since current theoretical framework(s) suggest an indirect lower limit on coset gauge boson masses of > or approx. 3 TeV, luminosity or energy upgrade of LHC is likely to be crucial in observing these states.« less