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Yuehong Xie

Publications and source records attributed to Yuehong Xie.

11 recordsLinked to original sources
arXiv2026

Low-energy Muon-Nucleon scattering experiment: LUNE (White Paper)

The HIAF will provide high-intensity, high-quality muon beams with momenta from 0.5 to 7.5 GeV/c. This energy range is uniquely suited for precision muon scattering, bridging the gap between low-energy electron facilities and future high-energy lepton-ion colliders. In particular, HIAF will enable precision measurements with both positive and negative muon beams over a broad kinematic range, complementing existing electron-scattering facilities such as JLab, EicC and EIC. Based on HIAF muon source, the LUNE Collaboration has been established to address several fundamental questions in nuclear and particle physics, including the proton charge radius puzzle, nucleon electromagnetic structure, and the dynamics of quantum electrodynamics and hadronic interactions. The program proceeds in two phases, from elastic scattering to nucleon structure and beyond-Standard-Model searches. The experiment is expected to determine the proton charge radius with a precision of approximately 1.0\% using elastic muon-proton scattering. It will also perform systematic measurements of the proton electromagnetic form factors with both $μ^+$ and $μ^-$ beams, enabling precise studies of two-photon exchange effects and stringent tests of quantum electrodynamics. Beyond elastic scattering, LUNE will investigate TMD, gravitational form factors, and nuclear charge radii, providing new insights into the 3D structure of nucleons and nuclei. The experiment will further address important topics including Coulomb-distortion corrections, nuclear medium effects, and possible signatures of physics beyond the Standard Model. This white paper presents the scientific motivation, detector concept, expected performance, and long-term strategy of LUNE.

hep-ex↗
arXiv2023

CP violation in heavy-flavour decays

The CKM matrix is the only source of CP violation in the Standard Model.Heavy-flavour decays provide an ideal laboratory to test the CKM mechanism. Some recent highlights in CP violation in heavy-flavour decays from the LHCb and Belle II experiments are presented, including updated measurements of the CKM angles $β$, $γ$ and $ϕ_s$, and new results in CP violation in charm decays.

hep-ex↗
arXiv2023

Heavy Flavour Physics and CP Violation at LHCb: a Ten-Year Review

Heavy flavour physics provides excellent opportunities to indirectly search for new physics at very high energy scales and to study hadron properties for deep understanding of the strong interaction. The LHCb experiment has been playing a leading role in the study of heavy flavour physics since the start of the LHC operations about ten years ago, and made a range of high-precision measurements and unexpected discoveries, which may have far-reaching implications on the field of particle physics. This review highlights a selection of the most influential physics results on CP violation, rare decays, and heavy flavour production and spectroscopy obtained by LHCb using the data collected during the first two operation periods of the LHC. The upgrade plan of LHCb and the physics prospects are also briefly discussed.

hep-ex↗
arXiv2015

Penguin Pollution in $B\to J/ψV$ Decays and Impact on the Extraction of the $B_s-\bar B_s$ mixing phase

We formulate the most-general time-dependent decay distributions of $B_s\to J/ψ(\to l^+l^-) ϕ(\to K^+K^-)$ in which the direct CP violation is explicitly incorporated. We then investigate the $B \to J/ψV$ decays in the perturbative QCD approach where $V$ is a light vector meson. Apart from the leading-order factorizable contributions, we also take into account various QCD corrections and the hard-spectator diagrams. With the inclusion of these sizable corrections, our theoretical results for CP-averaged branching ratios, polarization fractions, CP-violating asymmetries, and relative phases are in good consistency with the available data. Based on the global agreement, we further explore the penguin contributions and point out that the $ϕ_s$ extracted from $B_s\to J/ψϕ$ can be shifted away by ${\cal O}(10^{-3})$.

hep-ph↗
arXiv2012

CP Violation in Bs->J/psi phi

Study of CP violation in the decay channel Bs->J/psi phi is essential to exploring and constraining physics beyond the Standard Model in the quark flavour sector. The experimental progress in this area of activity at the LHC and Tevatron is discussed.

hep-ex↗
arXiv2009

Determination of 2beta_s in B_s -> J/psi K^+ K^- Decays in the Presence of a K^+K^- S-Wave Contribution

We present the complete differential decay rates for the process B_s -> J/psi K^+ K^- including S-wave and P-wave angular momentum states for the K^+ K^- meson pair. We examine the effect of an S-wave component on the determination of the CP violating phase 2beta_s. Data from the B-factories indicate that an S-wave component of about 10% may be expected in the phi(1020) resonance region. We find that if this contribution is ignored in the analysis it could cause a bias in the measured value of 2beta_s towards zero of the order of 10%. When including the K^+K^- S-wave component we observe an increase in the statistical error on 2beta_s by less than 15%. We also point out the possibility of measuring the sign of cos2beta_s by using the interference between the K^+K^- S-wave and P-wave amplitudes to resolve the strong phase ambiguity. We conclude that the S-wave component can be properly taken into account in the analysis.

hep-ph↗
arXiv2009

sFit: a method for background subtraction in maximum likelihood fit

This paper presents a statistical method to subtract background in maximum likelihood fit, without relying on any separate sideband or simulation for background modeling. The method, called sFit, is an extension to the sPlot technique originally developed to reconstruct true distribution for each date component. The sWeights defined for the sPlot technique allow to construct a modified likelihood function using only the signal probability density function and events in the signal region. Contribution of background events in the signal region to the likelihood function cancels out on a statistical basis. Maximizing this likelihood function leads to unbiased estimates of the fit parameters in the signal probability density function.

physics.data-an↗
arXiv2009

Formalism for Simulation-based Optimization of Measurement Errors in High Energy Physics

Miminizing errors of the physical parameters of interest should be the ultimate goal of any event selection optimization in high energy physics data analysis involving parameter determination. Quick and reliable error estimation is a crucial ingredient for realizing this goal. In this paper we derive a formalism for direct evaluation of measurement errors using the signal probability density function and large fully simulated signal and background samples without need for data fitting and background modelling. We illustrate the elegance of the formalism in the case of event selection optimization for CP violation measurement in B decays. The implication of this formalism on choosing event variables for data analysis is discussed.

hep-ex↗
arXiv2008

Exploiting the width difference in B_s -> phi gamma

The photon polarization in B -> V gamma is a sensitive probe of right-handed currents. In the time dependent decay rate of B_s -> phi gamma the coefficients S and H in front of the sin(Delta m_s t) and the sinh(Delta Gamma_s /2 t) terms are sensitive to those right-handed currents. As compared to the B_d system there is a sizable width difference in B_s mesons which leads to the additional measurable observable H. We show with a Monte Carlo simulation that the expected resolution on S and H will be about 0.15 at the LHCb experiment for Delta Gamma_s/Gamma_s = 0.15 and a data sample of 2 fb^{-1}. We also show that the observable H can be measured from the untagged decay rate of B_s mesons which has considerable experimental advantages as no flavour tag will be required. The resolution on H is inversely proportional to the B_s width difference Delta Gamma_s. These experimental prospects have to be compared with the Standard Model predictions S_{phi gamma} = 0 \pm 0.002 and H_{phi γ} = 0.047 \pm 0.025+0.015 presented in this paper. We also give the Standard Model prediction and the experimental sensitivity for the direct CP asymmetry in B_s -> phi gamma.

hep-ph↗
arXiv2007

LHCb strategies for gamma from B to DK

One of the most promising ways to determine the angle gamma of the CKM unitarity triangle is through measurement of the tree level processes B to DK. The LHCb collaboration has studied the potential of these decays employing the Atwood-Dunietz-Soni (ADS) and Dalitz methods, making use of a large sample of simulated data. For each method the expected sensitivities to the angle gamma are presented in this report.

hep-ex↗