IPM - Institute for Research in Fundamental Sciences

“School of Particles And Accelerator”

Paper IPM / Particles And Accelerator / 15750

School of Particles and Accelerator

Title:

LHC Constraints on a

$(B-L)_3$ Gauge Boson

Author(s):

1.	Fatemeh Elahi
2.	Adam Martin

Status:

Published

Journal:

Phys. Rev. D

Vol.:

100

Year:

2019

Supported by:

IPM

Abstract:

In this paper, we explore the constraints that the LHC can place on a massive gauge boson

$X$ that predominantly couples to the third generation of fermions. Such a gauge boson arises in scenarios where the

$B-L$ of the third generation is gauged. We focus on the mass range

$10 \leq \mx \lesssim 2\,m_W$ , where current constraints are lacking, and develop a dedicated search strategy. For this mass range, we show that

$b \bar b \tau^+ \tau^-$ , where at least one of the

$\tau$ s decay leptonically is the optimal channel to look for the

$X$ at the LHC. The QCD production of

$b$ quarks, combined with the cleanliness of the leptons coming from the decay of the

$\tau$ allow us to detect

$X$ gauge boson with couplings of

$\gx \sim(0.005-0.01)$ , for

$\mx < 50 \gev$ , and a coupling of

$O(0.1)$ for heavier

$X$ gauge boson with

$100 \fb^{-1}$ of integrated luminosity. This is about a factor of 2-10 improvement over previous constraints coming from the decay of

$\Upsilon \to \tau^+ \tau^-$ . Extrapolating to the full HL-LHC luminosity of

$3000 \fb^{-1}$ , the bounds on

$\gx$ can be enhanced by another factor of

$\sqrt{2}$ for

$\mx < 50 \gev$ .

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