arXiv subjects

Y. Chen

Publications and source records attributed to Y. Chen.

At least 217 records · Page 12Linked to original sources

arXiv2023

First measurement of quasi-elastic $Λ$ baryon production in muon anti-neutrino interactions in the MicroBooNE detector

We present the first measurement of the cross section of Cabibbo-suppressed $Λ$ baryon production, using data collected with the MicroBooNE detector when exposed to the neutrinos from the Main Injector beam at the Fermi National Accelerator Laboratory. The data analyzed correspond to $2.2 \times 10^{20}$ protons on target of neutrino mode running and $4.9 \times 10^{20}$ protons on target of anti-neutrino mode running. An automated selection is combined with hand scanning, with the former identifying five candidate $Λ$ production events when the signal was unblinded, consistent with the GENIE prediction of $5.3 \pm 1.1$ events. Several scanners were employed, selecting between three and five events, compared with a prediction from a blinded Monte Carlo simulation study of $3.7 \pm 1.0$ events. Restricting the phase space to only include $Λ$ baryons that decay above MicroBooNE's detection thresholds, we obtain a flux averaged cross section of $2.0^{+2.2}_{-1.7} \times 10^{-40}$ cm$^2/$Ar, where statistical and systematic uncertainties are combined.

hep-ex↗

arXiv2023

Multi-scale evolution of charmed particles in a nuclear medium

Parton energy-momentum exchange with the quark gluon plasma (QGP) is a multi-scale problem. In this work, we calculate the interaction of charm quarks with the QGP within the higher twist formalism at high virtuality and high energy using the MATTER model, while the low virtuality and high energy portion is treated via a (linearized) Boltzmann Transport (LBT) formalism. Coherence effect that reduces the medium-induced emission rate in the MATTER model is also taken into account. The interplay between these two formalisms is studied in detail and used to produce a good description of the D-meson and charged hadron nuclear modification factor RAA across multiple centralities. All calculations were carried out utilizing the JETSCAPE framework.

nucl-th↗

arXiv2023

Inclusive jet and hadron suppression in a multistage approach

We present a new study of jet interactions in the quark-gluon plasma created in high-energy heavy-ion collisions, using a multistage event generator within the JETSCAPE framework. We focus on medium-induced modifications in the rate of inclusive jets and high transverse momentum (high-$p_{\mathrm{T}}$) hadrons. Scattering-induced jet energy loss is calculated in two stages: A high virtuality stage based on the MATTER model, in which scattering of highly virtual partons modifies the vacuum radiation pattern, and a second stage at lower jet virtuality based on the LBT model, in which leading partons gain and lose virtuality by scattering and radiation. Coherence effects that reduce the medium-induced emission rate in the MATTER phase are also included. The TRENTo model is used for initial conditions, and the (2+1)dimensional VISHNU model is used for viscous hydrodynamic evolution. Jet interactions with the medium are modeled via 2-to-2 scattering with Debye screened potentials, in which the recoiling partons are tracked, hadronized, and included in the jet clustering. Holes left in the medium are also tracked and subtracted to conserve transverse momentum. Calculations of the nuclear modification factor ($R_{\mathrm{AA}}$) for inclusive jets and high-$p_{\mathrm{T}}$ hadrons are compared to experimental measurements at the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC). Within this framework, we find that with one extra parameter which codifies the transition between stages of jet modification -- along with the typical parameters such as the coupling in the medium, the start and stop criteria etc. -- we can describe these data at all energies for central and semicentral collisions without a rescaling of the jet transport coefficient $\hat{q}$.

hep-ph↗

arXiv2023

Study of $e^+e^- \rightarrow Σ^0 \overlineΣ{}^0$ and $Σ^+\overlineΣ{}^- $ by Initial State Radiation Method at Belle

The processes $ e^+e^-\rightarrow Σ^0\overlineΣ{}^0 $ and $ e^+e^-\rightarrowΣ^+\overlineΣ{}^-$ are studied using initial-state-radiation events in a sample of 980 $\,\mbox{fb}^{-1}$ collected with the Belle detector at the KEKB asymmetric-energy $ e^+e^- $ collider. The cross sections from the mass threshold to $ 3{\mathrm{\,Ge\kern -0.1em V\!/}c^2} $ and the effective form factors of $ Σ^0 $ and $ Σ^+ $ are measured. In the charmonium region, we observe the decays $J/ψ\rightarrowΣ^0\overlineΣ{}^0$ and $J/ψ\rightarrowΣ^+\overlineΣ{}^-$ and determine the respective branching fractions.

hep-ex↗

arXiv2023

Hot QCD White Paper

Hot QCD physics studies the nuclear strong force under extreme temperature and densities. Experimentally these conditions are achieved via high-energy collisions of heavy ions at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). In the past decade, a unique and substantial suite of data was collected at RHIC and the LHC, probing hydrodynamics at the nucleon scale, the temperature dependence of the transport properties of quark-gluon plasma, the phase diagram of nuclear matter, the interaction of quarks and gluons at different scales and much more. This document, as part of the 2023 nuclear science long range planning process, was written to review the progress in hot QCD since the 2015 Long Range Plan for Nuclear Science, as well as highlight the realization of previous recommendations, and present opportunities for the next decade, building on the accomplishments and investments made in theoretical developments and the construction of new detectors. Furthermore, this document provides additional context to support the recommendations voted on at the Joint Hot and Cold QCD Town Hall Meeting, which are reported in a separate document.

nucl-ex↗

arXiv2023

GRANDMA and HXMT Observations of GRB 221009A -- the Standard-Luminosity Afterglow of a Hyper-Luminous Gamma-Ray Burst

GRB 221009A is the brightest Gamma-Ray Burst (GRB) detected in more than 50 years of study. In this paper, we present observations in the X-ray and optical domains after the GRB obtained by the GRANDMA Collaboration (which includes observations from more than 30 professional and amateur telescopes) and the Insight-HXMT Collaboration. We study the optical afterglow with empirical fitting from GRANDMA+HXMT data, augmented with data from the literature up to 60 days. We then model numerically, using a Bayesian approach, the GRANDMA and HXMT-LE afterglow observations, that we augment with Swift-XRT and additional optical/NIR observations reported in the literature. We find that the GRB afterglow, extinguished by a large dust column, is most likely behind a combination of a large Milky-Way dust column combined with moderate low-metallicity dust in the host galaxy. Using the GRANDMA+HXMT-LE+XRT dataset, we find that the simplest model, where the observed afterglow is produced by synchrotron radiation at the forward external shock during the deceleration of a top-hat relativistic jet by a uniform medium, fits the multi-wavelength observations only moderately well, with a tension between the observed temporal and spectral evolution. This tension is confirmed when using the extended dataset. We find that the consideration of a jet structure (Gaussian or power-law), the inclusion of synchrotron self-Compton emission, or the presence of an underlying supernova do not improve the predictions, showing that the modelling of GRB22109A will require going beyond the most standard GRB afterglow model. Placed in the global context of GRB optical afterglows, we find the afterglow of GRB 221009A is luminous but not extraordinarily so, highlighting that some aspects of this GRB do not deviate from the global known sample despite its extreme energetics and the peculiar afterglow evolution.

astro-ph.HE↗

arXiv2023

High Resolution 3D Strain and Orientation Mapping within a Grain of a Directed Energy Deposition Laser Additively Manufactured Superalloy

The industrialization of Laser Additive Manufacturing (LAM) is challenged by the undesirable microstructures and high residual stresses originating from the fast and complex solidification process. Non-destructive assessment of the mechanical performance controlling deformation patterning is therefore critical. Here, we use Dark Field X-ray Microscopy (DFXM) to non-destructively map the 3D intragranular orientation and strain variations throughout a surface breaking grain within a directed energy deposition nickel superalloy. DFXM results reveal a highly heterogenous 3D microstructure in terms of the local orientation and lattice strain. The grain comprises $\approx$ 5$μ$m-sized cells with alternating strain states, as high as 5 $\times 10^{-3}$, and orientation differences <0.5° . The DFXM results are compared to Electron Backscatter Diffraction measurements of the same grain from its cut-off surface. We discuss the microstructure developments during LAM, rationalising the development of the deformation patterning from the extreme thermal gradients during processing and the susceptibility for solute segregation.

cond-mat.mtrl-sci↗

arXiv2023

The Present and Future of QCD

This White Paper presents the community inputs and scientific conclusions from the Hot and Cold QCD Town Meeting that took place September 23-25, 2022 at MIT, as part of the Nuclear Science Advisory Committee (NSAC) 2023 Long Range Planning process. A total of 424 physicists registered for the meeting. The meeting highlighted progress in Quantum Chromodynamics (QCD) nuclear physics since the 2015 LRP (LRP15) and identified key questions and plausible paths to obtaining answers to those questions, defining priorities for our research over the coming decade. In defining the priority of outstanding physics opportunities for the future, both prospects for the short (~ 5 years) and longer term (5-10 years and beyond) are identified together with the facilities, personnel and other resources needed to maximize the discovery potential and maintain United States leadership in QCD physics worldwide. This White Paper is organized as follows: In the Executive Summary, we detail the Recommendations and Initiatives that were presented and discussed at the Town Meeting, and their supporting rationales. Section 2 highlights major progress and accomplishments of the past seven years. It is followed, in Section 3, by an overview of the physics opportunities for the immediate future, and in relation with the next QCD frontier: the EIC. Section 4 provides an overview of the physics motivations and goals associated with the EIC. Section 5 is devoted to the workforce development and support of diversity, equity and inclusion. This is followed by a dedicated section on computing in Section 6. Section 7 describes the national need for nuclear data science and the relevance to QCD research.

hep-ph↗

arXiv2022

Comprehensive Study of Multi-scale Jet-medium Interaction

We explore jet-medium interactions at various scales in high-energy heavy-ion collisions using the JETSCAPE framework. The physics of the multi-stage modeling and the coherence effect at high virtuality is discussed through the results of multiple jet and high-$p_{\mathrm{T}}$ particle observables, compared with experimental data. Furthermore, we investigate the jet-medium interaction involved in the hadronization process.

hep-ph↗

arXiv2022

The first flare observation with a new solar microwave spectrometer working in 35-40 GHz

The microwave spectrum contains valuable information about solar flares. Yet, the present spectral coverage is far from complete and broad data gaps exist above 20 GHz. Here we report the first flare (the X2.2 flare on 2022 April 20) observation of the newly-built Chashan Broadband Solar millimeter spectrometer (CBS) working from 35 to 40 GHz. We use the CBS data of the new Moon to calibrate,and the simultaneous NoRP data at 35 GHz to cross-calibrate. The impulsive stage has three local peaks with the middle one being the strongest and the maximum flux density reaches 9300 SFU at 35-40 GHz. The spectral index of the CBS data (alpha_C) for the major peak is mostly positive, indicating the gyrosynchrotron turnover frequency (nu_t) goes beyond 35-40 GHz. The frequency nu_t is smaller yet still larger than 20 GHz for most time of the other two peaks according to the spectral fittings with NoRP-CBS data. The CBS index manifests the general rapid-hardening-then-softening trend for each peak and gradual hardening during the decay stage, agreeing with the fitted optically-thin spectral index (alpha_tn) for nu_t < 35 GHz. In addition, the obtained turnover frequency during the whole impulsive stage correlates well with the corresponding intensity (I_t) according to a power-law dependence (It~nu_t^4.8) with a correlation coefficient of 0.82.This agrees with earlier studies on flares with low turnover frequency (<17 GHz), yet being reported for the first time for events with a high turnover frequency (>20 GHz).

astro-ph.SR↗

arXiv2022

Measurement of neutral current single $π^0$ production on argon with the MicroBooNE detector

We report the first measurement of $π^0$ production in neutral current (NC) interactions on argon with average neutrino energy of $\lesssim1$~GeV. We use data from the MicroBooNE detector's 85-tonne active volume liquid argon time projection chamber situated in Fermilab's Booster Neutrino Beam and exposed to $5.89\times10^{20}$ protons on target for this measurement. Measurements of NC $π^0$ events are reported for two exclusive event topologies without charged pions. Those include a topology with two photons from the decay of the $π^0$ and one proton and a topology with two photons and zero protons. Flux-averaged cross-sections for each exclusive topology and for their semi-inclusive combination are extracted (efficiency-correcting for two-plus proton final states), and the results are compared to predictions from the \textsc{genie}, \textsc{neut}, and \textsc{NuWro} neutrino event generators. We measure cross sections of $1.243\pm0.185$ (syst) $\pm0.076$ (stat), $0.444\pm0.098\pm0.047$, and $0.624\pm0.131\pm0.075$ $[10^{-38}\textrm{cm}^2/\textrm{Ar}]$ for the semi-inclusive NC$π^0$, exclusive NC$π^0$+1p, and exclusive NC$π^0$+0p processes, respectively.

hep-ex↗

arXiv2022

Flux Variations of Cosmic Ray Air Showers Detected by LHAASO-KM2A During a Thunderstorm on 10 June 2021

The Large High Altitude Air Shower Observatory (LHAASO) has three sub-arrays, KM2A, WCDA and WFCTA. The flux variations of cosmic ray air showers were studied by analyzing the KM2A data during the thunderstorm on 10 June 2021. The number of shower events that meet the trigger conditions increases significantly in atmospheric electric fields, with maximum fractional increase of 20%. The variations of trigger rates (increases or decreases) are found to be strongly dependent on the primary zenith angle. The flux of secondary particles increases significantly, following a similar trend with that of the shower events. To better understand the observed behavior, Monte Carlo simulations are performed with CORSIKA and G4KM2A (a code based on GEANT4). We find that the experimental data (in saturated negative fields) are in good agreement with simulations, assuming the presence of a uniform upward electric field of 700 V/cm with a thickness of 1500 m in the atmosphere above the observation level. Due to the acceleration/deceleration and deflection by the atmospheric electric field, the number of secondary particles with energy above the detector threshold is modified, resulting in the changes in shower detection rate.

astro-ph.HE↗

arXiv2022

Search for long-lived heavy neutral leptons and Higgs portal scalars decaying in the MicroBooNE detector

We present a search for long-lived Higgs portal scalars (HPS) and heavy neutral leptons (HNL) decaying in the MicroBooNE liquid-argon time projection chamber. The measurement is performed using data collected synchronously with the NuMI neutrino beam from Fermilab's Main Injector with a total exposure corresponding to $7.01 \times 10^{20}$ protons on target. We set upper limits at the $90\%$ confidence level on the mixing parameter $\lvert U_{μ4}\rvert^2$ ranging from $\lvert U_{μ4}\rvert^2<12.9\times 10^{-8}$ for Majorana HNLs with a mass of $m_{\rm HNL}=246$ MeV to $\lvert U_{μ4}\rvert^2<0.92 \times 10^{-8}$ for $m_{\rm HNL}=385$ MeV, assuming $\lvert U_{e 4}\rvert^2 = \lvert U_{τ4}\rvert^2 = 0$ and HNL decays into $μ^\pmπ^\mp$ pairs. These limits on $\lvert U_{μ4}\rvert^2$ represent an order of magnitude improvement in sensitivity compared to the previous MicroBooNE result. We also constrain the scalar-Higgs mixing angle $θ$ by searching for HPS decays into $μ^+μ^-$ final states, excluding a contour in the parameter space with lower bounds of $θ^2<31.3 \times 10^{-9}$ for $m_{\rm HPS}=212$ GeV and $θ^2<1.09 \times 10^{-9}$ for $m_{\rm HPS}=275$ GeV. These are the first constraints on the scalar-Higgs mixing angle $θ$ from a dedicated experimental search in this mass range.

hep-ex↗

arXiv2022

First constraints on light sterile neutrino oscillations from combined appearance and disappearance searches with the MicroBooNE detector

We present a search for eV-scale sterile neutrino oscillations in the MicroBooNE liquid argon detector, simultaneously considering all possible appearance and disappearance effects within the $3+1$ active-to-sterile neutrino oscillation framework. We analyze the neutrino candidate events for the recent measurements of charged-current $ν_e$ and $ν_μ$ interactions in the MicroBooNE detector, using data corresponding to an exposure of 6.37$\times$10$^{20}$ protons on target from the Fermilab booster neutrino beam. We observe no evidence of light sterile neutrino oscillations and derive exclusion contours at the $95\%$ confidence level in the plane of the mass-squared splitting $Δm^2_{41}$ and the sterile neutrino mixing angles $θ_{μe}$ and $θ_{ee}$, excluding part of the parameter space allowed by experimental anomalies. Cancellation of $ν_e$ appearance and $ν_e$ disappearance effects due to the full $3+1$ treatment of the analysis leads to a degeneracy when determining the oscillation parameters, which is discussed in this paper and will be addressed by future analyses.

hep-ex↗

arXiv2022

Precision measurement of reactor antineutrino oscillation at kilometer-scale baselines by Daya Bay

We present a new determination of the smallest neutrino mixing angle $θ_{13}$ and the mass-squared difference $Δ{\rm m}^{2}_{32}$ using a final sample of $5.55 \times 10^{6}$ inverse beta-decay (IBD) candidates with the final-state neutron captured on gadolinium. This sample was selected from the complete data set obtained by the Daya Bay reactor neutrino experiment in 3158 days of operation. Compared to the previous Daya Bay results, selection of IBD candidates has been optimized, energy calibration refined, and treatment of backgrounds further improved. The resulting oscillation parameters are ${\rm sin}^{2}2θ_{13} = 0.0851 \pm 0.0024$, $Δ{\rm m}^{2}_{32} = (2.466 \pm 0.060) \times 10^{-3}{\rm eV}^{2}$ for the normal mass ordering or $Δ{\rm m}^{2}_{32} = -(2.571 \pm 0.060) \times 10^{-3} {\rm eV}^{2}$ for the inverted mass ordering.

hep-ex↗

arXiv2022

Enhanced strong-coupling stimulated Brillouin amplification assisted by Raman amplification

Higher intensity of strong-coupling stimulated Brillouin scattering (SC-SBS) amplification is achieved by supplementary Raman amplification. In the new scheme, a Raman pump laser first amplifies the seed pulse in the homogeneous plasma, then a SC-SBS pump laser continues the amplification in the inhomogeneous plasma in order to suppress the spontaneous instability of pump lasers. The intensity of seed laser gets higher and the duration of seed laser gets shorter than that in the pure SC-SBS scheme with the same incident energy, while the energy conversion effciency is not significantly reduced. We also found that the SC-SBS amplification is seeded by the πpulse of Raman amplification. The results obtained from envelope coupling equations, Vlasov simulations and two-dimensional particle-in-cell(PIC) simulations agree with each other. This scheme is a simple and effective way to improve the SC-SBS amplification and is easy to implement in experiments.

physics.plasm-ph↗

arXiv2022

Observation of Radon Mitigation in MicroBooNE by a Liquid Argon Filtration System

The MicroBooNE liquid argon time projection chamber (LArTPC) maintains a high level of liquid argon purity through the use of a filtration system that removes electronegative contaminants in continuously-circulated liquid, recondensed boil off, and externally supplied argon gas. We use the MicroBooNE LArTPC to reconstruct MeV-scale radiological decays. Using this technique we measure the liquid argon filtration system's efficacy at removing radon. This is studied by placing a 500 kBq $^{222}$Rn source upstream of the filters and searching for a time-dependent increase in the number of radiological decays in the LArTPC. In the context of two models for radon mitigation via a liquid argon filtration system, a slowing mechanism and a trapping mechanism, MicroBooNE data supports a radon reduction factor of greater than 99.999% or 97%, respectively. Furthermore, a radiological survey of the filters found that the copper-based filter material was the primary medium that removed the $^{222}$Rn. This is the first observation of radon mitigation in liquid argon with a large-scale copper-based filter and could offer a radon mitigation solution for future large LArTPCs.

physics.ins-det↗

arXiv2022

Purification-based quantum error mitigation of pair-correlated electron simulations

An important measure of the development of quantum computing platforms has been the simulation of increasingly complex physical systems. Prior to fault-tolerant quantum computing, robust error mitigation strategies are necessary to continue this growth. Here, we study physical simulation within the seniority-zero electron pairing subspace, which affords both a computational stepping stone to a fully correlated model, and an opportunity to validate recently introduced ``purification-based'' error-mitigation strategies. We compare the performance of error mitigation based on doubling quantum resources in time (echo verification) or in space (virtual distillation), on up to $20$ qubits of a superconducting qubit quantum processor. We observe a reduction of error by one to two orders of magnitude below less sophisticated techniques (e.g. post-selection); the gain from error mitigation is seen to increase with the system size. Employing these error mitigation strategies enables the implementation of the largest variational algorithm for a correlated chemistry system to-date. Extrapolating performance from these results allows us to estimate minimum requirements for a beyond-classical simulation of electronic structure. We find that, despite the impressive gains from purification-based error mitigation, significant hardware improvements will be required for classically intractable variational chemistry simulations.

quant-ph↗