Abstract
We study FASER and FASER 2 sensitivities to the quirk signal by simulating the motions of quirks that are travelling through several infrastructures from the ATLAS interaction point to the FASER (2) detector. The ionization energy losses for a charged quirk travelling in different materials are treated carefully. We calculate the expected numbers of quirk events that can reach the FASER (2) detector for an integrated luminosity of 150 (3000) fb−1. Scenarios for quirks with four different quantum numbers, and different masses and confinement scales are studied.
Highlights
We study FASER and FASER 2 sensitivities to the quirk signal by simulating the motions of quirks that are travelling through several infrastructures from the ATLAS interaction point to the FASER (2) detector
We focus on the FASER (2) experiment in this work, which is located 480 m downstream from the ATLAS interaction point (IP)
The ionization force on quirks will change their trajectories, which can be observed in figure 2 where the trajectories of the quirk pair between the ATLAS IP and FASER (2) has been twisted when Λ = 400 eV
Summary
In order to solve the little hierarchy problem [34, 35], some models beyond the Standard Model (BSM) with neutral naturalness [36] predict the existence of color neutral quirk particles. In the middle and right panels of figure 1, we plot the fractions of events that have pT (QQ)/|p(QQ)| < 0.005 and 0.002 for different quirks, where pT (QQ) and |p(QQ)| are the transverse momentum and the momentum size of the quirk-pair system, respectively Note that these selections keep events with QQ system travelling opposite to the Z-axis, which obviously can not reach FASER (2). The mean rates of energy loss for charged particle traveling through concrete, copper, and rock, supposing z = 1 and me/M 1. The ionization energy loss for a charged particle travelling a distance δx in the material fluctuates, which, in the BB region, can be described by a Gaussian distribution when δx is large enough such that ξ(δx) Wmax. At each time grid of our simulation, the −dE/dx is randomly generated by the PDF in eq (3.9) and the Fion is calculated by eq (3.3)
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