高能物理 - 实验
Axions are well-motivated dark matter candidates with simple cosmological production mechanisms. They were originally introduced to solve the strong CP problem, but also arise in a wide range of extensions to the Standard Model. This…
We report on recent progress and next steps in the design of the proposed MATHUSLA Long Lived Particle (LLP) detector for the HL-LHC as part of the Snowmass 2021 process. Our understanding of backgrounds has greatly improved, aided by…
Protons consist of three valence quarks, two up-quarks and one down-quark, held together by gluons and a sea of quark-antiquark pairs. Collectively, quarks and gluons are referred to as partons. In a proton-proton collision, typically only…
We present the first measurements of the electric and magnetic form factors of the neutron in the time-like (positive $q^2$) region as function of four-momentum transfer. We explored the differential cross sections of the reaction $e^+e^-…
We report a study of $\Lambda_c^+\to\Lambda h^+$ and $\Lambda_c^+\to\Sigma^{0} h^+$ ($h\!=\!K,\,\pi$) decays based on a data sample of 980~${\rm fb}^{-1}$ collected with the Belle detector at the KEKB energy-asymmetric $e^+e^-$ collider.…
The measurement of neutrino magnetic moment larger than $10^{-19}\mu_B$ would be a clear signature of physics beyond the standard model other than the existence of massive Dirac neutrinos. The use of a spherical proportional counter…
Data-driven methods are widely used to overcome shortcomings of Monte Carlo simulations (lack of statistics, mismodeling of processes, etc.) in experimental high energy physics. A precise description of background processes is crucial to…
We present the first search for the pair production of dark particles $X$ via $K_L^0\to XX$ with $X$ decaying into two photons using the data collected by the KOTO experiment. No signal was observed in the mass range of 40 - 110 MeV/c$^2$…
We measure the branching fraction for the Singly Cabibbo-suppressed decay $D^0\rightarrow K^0_S\,K^0_S\,\pi^+\pi^-$, and we search for $CP$ violation via a measurement of the $CP$ asymmetry $A^{}_{CP}$ and also the $T$-odd triple-product…
The Alpha Magnetic Spectrometer (AMS) is a precision particle physics detector operating at an altitude of 410 km aboard the International Space Station. The AMS silicon tracker, together with the permanent magnet, measures the rigidity…
It is generally accepted that it is preferable to build two general purpose detectors at any given collider facility. We reinforce this point by discussing a number of aspects and particular instances in which this has been important. The…
Many new exotic hadrons, that do not fit into the existing naming scheme for hadrons, have been discovered over the past few years. A new scheme is set out, extending the existing protocol, in order to provide a consistent naming convention…
This paper reports world averages of measurements of $b$-hadron, $c$-hadron, and $\tau$-lepton properties obtained by the Heavy Flavour Averaging Group using results available before April 2021. In rare cases, significant results obtained…
The Born cross sections of the process $e^{+}e^{-}\to D^{*0}D^{*-}\pi^{+}$ at center-of-mass energies from 4.189 to 4.951 GeV are measured for the first time. The data samples used correspond to an integrated luminosity of $17.9\,{\rm…
Using a sample of $(10.09\pm0.04)\times10^{9}$ $J/\psi$ decays collected with the BESIII detector, partial wave analyses of the decay $J/\psi\to\gamma K^{0}_{S} K^{0}_{S}\pi^{0}$ are performed within the $K^{0}_{S}K^{0}_{S}\pi^{0}$…
The DAMA/LIBRA collaboration has reported the observation of an annual modulation in the event rate that has been attributed to dark matter interactions over the last two decades. However, even though tremendous efforts to detect similar…
Using 448 million $\psi(2S)$ events, the spin-singlet $P$-wave charmonium state $h_c$(1$^1P_1$) is studied via the $\psi(2S) \rightarrow \pi^0 h_c$ decay followed by the $h_c \to \gamma \eta_c$ transition. The branching fractions are…
This article reviews recent cross-section measurements of top-quark pair production in association with a photon, W or Z boson at the Large Hadron Collider (LHC). All measurements reviewed use proton-proton (pp) datasets collected by the…
BESIII is the particle detector of the Beijing Electron-Positron Collider, which is a {\tau} -charm factory working at energies around 4 GeV. The first part of the detector, around the collision site, is called the Main Drift Chamber, MDC.…
The analysis of the time profile of electrical signals produced by energy depositions in germanium detectors allows discrimination of events with different topologies. This is especially relevant for experiments searching for the…