arXiv subjects

Ming Xiong Liu

Publications and source records attributed to Ming Xiong Liu.

6 recordsLinked to original sources

arXiv2025

Dedicated Searches for Millicharged Particles at Intensity-Frontier Facilities: SpinQuest and SHiP

We conduct a dedicated study of searches for millicharged particles (mCPs) utilizing scintillator-based detectors at high-intensity fixed-target experiments, with particular focus on the SpinQuest and forthcoming Search for Hidden Particles experiment (SHiP) facilities. The analysis incorporates the three primary production mechanisms: meson decays, Drell-Yan processes, and proton bremsstrahlung. In particular, our updated analysis reveals that proton bremsstrahlung dominates the production rate in the sub-GeV mass regime. Detailed detector simulations and background evaluations are performed to obtain realistic sensitivity estimates. Our results demonstrate that future experiments located in the SpinQuest and SHiP facilities can achieve substantial improvements in discovery potential, enhancing sensitivity to the mCP charge parameter $ε=q_χ/e$ (with $q_χ$ denoting the mCP electric charge) by up to two orders of magnitude relative to existing limits.

hep-ph↗

arXiv2024

LANSCE-mQ: Dedicated search for milli/fractionally charged particles at LANL

In this paper, we propose an experiment, LANSCE-mQ, aiming to detect fractionally charged and millicharged particles (mCP) using an 800 MeV proton beam fixed target at the Los Alamos Neutron Science Center (LANSCE) facility. This search can shed new light on numerous fundamental questions, including charge quantization, the predictions of string theories and grand unification theories, the gauge symmetry of the Standard Model, dark sector models, and the tests of cosmic reheating. We propose to install two-layer scintillation detectors made of plastic (such as EJ-200) or CeBr3 to search for mCPs. Dedicated Geant4 detector simulations and in situ measurements have been conducted to obtain a preliminary determination of the background rate. The dominant backgrounds are beam-induced neutrons and coincident dark current signals from the photomultiplier tubes, while beam-induced gammas and cosmic muons are subdominant. We determined that LANSCE-mQ, the dedicated mCP experiment, has the leading mCP sensitivity for mass between ~ 1 MeV to 300 MeV.

hep-ph↗

arXiv2020

A Proposed Forward Silicon Tracker for the Future Electron-Ion Collider and Associated Physics Studies

The future Electron-Ion Collider (EIC) will explore several fundamental questions in a broad Bjorken-x ($x_{BJ}$) and $Q^{2}$ phase space. Heavy flavor and jet products are ideal probes to precisely study the tomography of nucleon/nuclei structure, help solve the proton spin puzzle and understand the hadronizaton processes in vacuum or in the QCD medium. Due to the asymmetric collisions at the EIC, most of the final state hadrons are produced in the nucleon/nuclei beam going (forward) direction. A silicon vertex/tracking is critical to precisely measure these forward hadrons at the EIC. Details of different conceptual designs of the proposed Forward Silicon Tracker (FST) and the relevant detector performance are presented in this technical note. The associated heavy flavor and jet studies with the evaluated FST performance are discussed as well.

nucl-ex↗

arXiv2019

The High-Energy Frontier of the Intensity Frontier: Closing the Dark Photon, Inelastic Dark Matter, and Muon g-2 Windows

We study hidden sector and long-lived particles at past (CHARM and NuCal), present (NA62 and SeaQuest/DarkQuest), and future (LongQuest) experiments that are at the high-energy frontier of the intensity frontier. We focus on exploring the minimal vector portal and variere-lifetime particles (VLP). VLP models have mostly been devised to explain experimental anomalies while avoiding existing constraints, and we demonstrate that proton fixed-target experiments provide one of the most powerful probes for the sub-GeV to few GeV mass range of the VLP models, using inelastic dark matter (iDM) as an example. We consider an iDM model with small mass splitting that yields the observed dark matter (DM) relic abundance, and a scenario with a sizable mass splitting that can also explain the muon $g-2$ anomaly. We set strong limits based on the CHARM and NuCal experiments, which come close to excluding iDM as full-abundance thermal DM candidates in the MeV to GeV mass range, for the mass arrangements and small mass splittings we consider. We also study the future projections based on NA62 and SeaQuest/DarkQuest, and update the constraints of the minimal dark photon parameter space. We found that NuCal sets the only existing constraint in $ε\sim 10^{-8} - 10^{-4}$ regime reaching $\sim$ 800 MeV in dark photon mass due to the resonant enhancement of the proton bremsstrahlung production. Finally, we propose LongQuest, a three-stage thorough retool of the SeaQuest experiment with short ($\lesssim$ 5 m), medium ($\sim$ 5 m), and long baseline ($\gtrsim$ 35 m) tracking stations/detectors, as a multi-purpose machine to explore dark sector particles with a wide range of couplings to the standard model sector.

hep-ph↗

arXiv2004

Charm Production at RHIC

The latest results for open charm and $J/ψ$ production in p-p, d-Au and Au-Au from the PHENIX and STAR experiments at $\sqrt{s_{NN}}=200$ GeV at RHIC are presented. The preliminary data show open charm production follows binary scaling in d-Au and Au-Au collisions at RHIC. In d-Au collisions, a suppression in $J/ψ$ production has been observed at the forward rapidity (d direction), at the backward rapidity (Au direction), $J/ψ$ production seems strongly dependent on collisions centrality. The implications of heavy flavor production in cold (d-Au) and hot (Au-Au) nuclear media at RHIC are discussed.

nucl-ex↗

arXiv2004

Hadron production in the forward and backward rapidities in dAu collisions at RHIC

We have developed new techniques to detect hadrons with the PHENIX muon spectrometers. This allows us to study the centrality dependent nuclear modification factor $R_{CP}$ with high $p_{T}$ hadrons in both forward (d direction) and backward (Au direction) rapidities, $1 < |η| < 2$, in dAu collisions at $\sqrt{s_{NN}} = 200 GeV$. Preliminary results show a suppression (enhancement) of high $p_{T}$ hadron production in central $0-20%$ dAu collisions relative to the peripheral one ($60-88%$ in centrality) at forward (backward) rapidity.

nucl-ex↗