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Reappraisal of constraints on Z′ models from unitarity and direct searches at the LHC

Bandyopadhyay, Triparno; Bhattacharyya, Gautam; Das, Dipankar LU and Raychaudhuri, Amitava (2018) In Physical Review D 98(3).
Abstract

In a truly model-independent approach, we reexamine a minimal extension of the Standard Model (SM) through the introduction of an additional U(1) symmetry leading to a new neutral gauge boson (Z′), allowing its kinetic mixing with the hypercharge gauge boson. An SM neutral scalar is used to spontaneously break this extra symmetry, leading to the mass of the Z′. Except for three right-handed neutrinos, no other fermions are added. We use the current LHC Drell-Yan data to put model-independent constraints in the parameter space of three quantities, namely, MZ′, the Z-Z′ mixing angle (αz), and the extra U(1) effective gauge coupling (gx′), which absorb all model dependence. We impose additional constraints from unitarity and low-energy... (More)

In a truly model-independent approach, we reexamine a minimal extension of the Standard Model (SM) through the introduction of an additional U(1) symmetry leading to a new neutral gauge boson (Z′), allowing its kinetic mixing with the hypercharge gauge boson. An SM neutral scalar is used to spontaneously break this extra symmetry, leading to the mass of the Z′. Except for three right-handed neutrinos, no other fermions are added. We use the current LHC Drell-Yan data to put model-independent constraints in the parameter space of three quantities, namely, MZ′, the Z-Z′ mixing angle (αz), and the extra U(1) effective gauge coupling (gx′), which absorb all model dependence. We impose additional constraints from unitarity and low-energy neutrino-electron scattering. However, limits extracted from direct searches turn out to be most stringent. We obtain MZ′>4.4 TeV and |αz|<0.001 at 95% C.L., when the strength of the additional U(1) gauge coupling is the same as that of the SM SU(2)L.

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author
publishing date
type
Contribution to journal
publication status
published
subject
in
Physical Review D
volume
98
issue
3
publisher
American Physical Society
external identifiers
  • scopus:85052656052
ISSN
2470-0010
DOI
10.1103/PhysRevD.98.035027
language
English
LU publication?
no
id
19548505-983e-4f8b-8c50-2c3ab81f3aed
date added to LUP
2019-05-22 15:20:23
date last changed
2019-11-13 05:34:01
@article{19548505-983e-4f8b-8c50-2c3ab81f3aed,
  abstract     = {<p>In a truly model-independent approach, we reexamine a minimal extension of the Standard Model (SM) through the introduction of an additional U(1) symmetry leading to a new neutral gauge boson (Z′), allowing its kinetic mixing with the hypercharge gauge boson. An SM neutral scalar is used to spontaneously break this extra symmetry, leading to the mass of the Z′. Except for three right-handed neutrinos, no other fermions are added. We use the current LHC Drell-Yan data to put model-independent constraints in the parameter space of three quantities, namely, MZ′, the Z-Z′ mixing angle (αz), and the extra U(1) effective gauge coupling (gx′), which absorb all model dependence. We impose additional constraints from unitarity and low-energy neutrino-electron scattering. However, limits extracted from direct searches turn out to be most stringent. We obtain MZ′&gt;4.4 TeV and |αz|&lt;0.001 at 95% C.L., when the strength of the additional U(1) gauge coupling is the same as that of the SM SU(2)L.</p>},
  articleno    = {035027},
  author       = {Bandyopadhyay, Triparno and Bhattacharyya, Gautam and Das, Dipankar and Raychaudhuri, Amitava},
  issn         = {2470-0010},
  language     = {eng},
  month        = {08},
  number       = {3},
  publisher    = {American Physical Society},
  series       = {Physical Review D},
  title        = {Reappraisal of constraints on Z′ models from unitarity and direct searches at the LHC},
  url          = {http://dx.doi.org/10.1103/PhysRevD.98.035027},
  volume       = {98},
  year         = {2018},
}