arXiv subjects

Longke Li

Publications and source records attributed to Longke Li.

7 recordsLinked to original sources

arXiv2025

The Imaging Time-of-Propagation Detector at Belle II

We report on the construction, operation, and performance of the Time-of-Propagation detector with imaging used for the Belle II experiment running at the Super-KEKB $e^+e^-$ collider. This detector is located in the central barrel region and uses Cherenkov light to provide particle identification among hadrons. The Cherenkov light is radiated in highly polished bars of synthetic fused silica (quartz) and transported to the ends of the bars via total internal reflection. One bar end is instrumented with finely segmented micro-channel-plate photomultiplier tubes to record the light, while the other end has a mirror attached to reflect the photons back to the instrumented end. Both the propagation times and hit positions of the Cherenkov photons are measured; these depend on the Cherenkov angle and together provide good discrimination among charged pions, kaons, and protons with momenta up to around 4 GeV/$c$. To date, the detector has been used to record and analyze almost 600 fb$^{-1}$ of Belle II data.

hep-ex↗

arXiv2025

Study $\Xi_c^+ \to \Lambda {\bar{K}}^0 \pi^+$ and search for the low-lying baryons $\Xi(1/2^-)$ and $\Sigma(1/2^-)$

Since searches for the low-lying excited baryons $\Xi(1/2^-)$ and $\Sigma(1/2^-)$ are crucial to deepening our understanding of the light baryon spectrum, we have investigated the Cabibbo-favored process $\Xi_c^+ \to \Lambda {\bar{K}}^0 \pi^+$ by taking into account the $S$-wave pseudoscalar meson-octet baryon interactions within the chiral unitary approach, which could dynamically generate the resonances $\Xi(1/2^-)$ and $\Sigma(1/2^-)$. The contributions from the excited kaons are double Cabibbo-suppressed, and the contribution from the $\Sigma(1385)$ is also suppressed due to Korner-Pati-Woo theory, thus those states are expected to play negligible contributions in this process. We have predicted the $\bar{K}^0 \Lambda$ and $\pi^+\Lambda$ invariant mass distributions, which have the clear signals of the $\Xi(1/2^-)$ and $\Sigma(1/2^-)$. Thus, the $\Xi_c^+ \to \Lambda {\bar{K}}^0 \pi^+$ is an ideal process to search for the low-lying baryons $\Xi(1/2^-)$ and $\Sigma(1/2^-)$, and we make a call for a precise measurements of this process in experiments, such as Belle II, LHCb, and the proposed Super Tau-Charm Facility (STCF).

hep-ph↗

arXiv2024

Charm physics at the Belle and Belle II experiments

We present recent results on charm physics at the Belle and Belle II experiments, covering measurements of charm lifetimes, branching fractions of the decays of charmed mesons and baryons and the decay asymmetry parameters of two-body decays of charmed baryons, searches for rare and forbidden decays, and measurements of $C\!P$ violating parameters in the four-body decays of charmed mesons and two-body decays of charmed baryons.

hep-ex↗

arXiv2021

Recent charm results at Belle

We present the selected recent charm results at Belle: (1) the $CP$ asymmetries and branching fractions for the decays of charm mesons, i.e. $D^{0}\to\pi^{+}\pi^{-}\eta,\,K^{+}K^{-}\eta$ and $D^{0}\to\phi\eta$; $D_{s}^{+}\to K^{+}\pi^{0},\,K^{+}\eta$ and $D_{s}^{+}\to\pi^{+}\pi^{0},\,\pi^{+}\eta$. (2) the branching fractions for the decays of charmed baryons, i.e. $\Lambda_{c}^{+}\to p\pi^{0},\,p\eta$; $\Lambda_{c}^{+}\to\Lambda\pi^{+}\eta,\,\Sigma^0\pi^{+}\eta$ and intermediate processes $\Lambda_{c}^{+}\to\Lambda(1670)\pi^{+},\,\eta\Sigma(1385)^+$; $\Xi_c^0\to\Lambda\bar{K}^{*0},\,\Sigma^0\bar{K}^{*0}$ and $\Sigma^+K^{*-}$. (3) properties of excited charmed baryons, i.e. search for electromagnetic transition $\Xi_c(2790,2815)^{+,0}\to\Xi_c^{+,0}\gamma$; and determination of spin-parity of $\Xi_c(2970)^+$.

hep-ex↗

arXiv2021

Recent charm results from Belle

Recent charm results from Belle experiment are presented in this proceedings, including (1) measurement of mixing parameter $y_{CP}=(0.96\pm0.91\pm 0.62^{+0.17}_{-0.00})\%$ in $CP$-odd decay for the first time, (2) the first Dalitz-plot analysis of $D^0\to K^-\pi^+\eta$, (3) measurement of branching fractions of $\Lambda_c^+\to\eta\Lambda^0\pi^+$ and $\eta\Sigma^0\pi^+$ and intermediate processes $\Lambda_c^+\to[\Lambda(1670)\to\eta\Lambda^0]\pi^+$ and $\Lambda_c^+\to\eta\Sigma(1385)^+$ relative to $\Lambda_c^+\to p K^-\pi^+$: $0.293\pm0.003\pm0.014$, $0.120\pm0.006\pm0.006$, $(5.54\pm0.29\pm0.73)\times10^{-2}$, and $0.192\pm 0.006\pm 0.016$, respectively, and (4) first determination of the spin and parity of a charmed-strange baryon $\Xi_c(2970)^+$ which is consistent with the HQSS prediction for $J^P(s_l)=1/2^+(0)$.

hep-ex↗

arXiv2015

Charm studies at Belle experiment

In this proceeding, we give a summary of the new published or preliminary experimental results on charm studies at Belle experiment at KEKB. It mainly includes three parts: (1) $D^0-\bar{D}^0$ mixing and CP violation. Some decay channels give the new measurement results with more precise; (2) search for $D^0$ rare decay with most restrictive upper limit; (3) some new results for charmed baryon studies, such as doubly charmed baryons, charmed strange baryon and so on.

hep-ex↗

arXiv2013

D^0-\bar{D}^0 Mixing and CP Violation in D^0-->K_{S}hh measurements

In these proceedings, we give a summary of the experimental results from CLEO, Belle, BaBar and CDF collaboration about $D^0-\bar{D}^0$ mixing and CP violation in self-conjugated-three-body decays $D^0\rightarrow K_S^0hh$ (where $h$ can be $π$ or $K$). We report preliminary results of measurement of $D^0-\bar{D}^0$ mixing and indirect CP violation in $D^0\rightarrow K_S^0π^+π^-$ decays using full data sample collected by Belle detector at KEKB asymmetric-energy $e^+e^-$ collider: give values for $x=(0.56\pm0.19^{+0.03+0.06}_{-0.09-0.09})%$, $y=(0.30\pm0.15^{+0.04+0.03}_{-0.05-0.06})%$, $|q/p|=0.90^{+0.16+0.05+0.06}_{-0.15-0.04-0.05}$ and $\arg(q/p)=-6\pm11^{+3+3}_{-3-4}(^o)$. We also report results of recent measurement searching for CP violation in $D^0\rightarrow K_S^0π^+π^-$ decays by CDF collaboration using $6.0 fb^{-1}$ of data collected in $p\bar{p}$ collisions at Tevatron. The phase-space-integrated CP asymmetry is measured to be $A_{CP}=(-0.05\pm0.57\pm0.54)%$ and the CP symmetry is also found to be conserved in all individual intermediate contributions.

hep-ex↗