Yangheng Zheng
Charm physics has been studied with many dedicated accelerators and experiments. In these proceedings, we review the status and the selected results of the current operating BEPCII/BESIII experiment. We also discuss the BESIII data taking plan for the future.
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The next generation tau-charm factory, the third Beijing Electron Spectrometer (BESIII) at the new Beijing Electron Positron Collider (BEPCII), has begun data collection. I discuss the flavor physics reach of the BESIII charm program and conclude with a discussion on future proposed tau-charm facilities.
The CHARM 2010 meeting had over 30 presentations of experimental results, plus additional future facilities talks just before this summary talk. Since there is not enough time even to summarize all that has been shown from experiments and to recognize all the memorable plots and results, this summary will give a few personal observations, an overview at a fairly high level of abstraction.
Charm from Hyperonsin the Future: Fermilab Experiment 781
CERN WA 89实验的最新结果表明，粲重子，特别是粲奇异重子在$Σ^-$束流中具有显著的截面。目前正在建设中的费米实验室781实验将利用这一事实，在下一次费米实验室固定目标运行中进行一项广泛的粲重子高统计研究计划。
b and c hadrons are instrumental to the identification and study of the Higgs sector and new physics at a future lepton collider. This paper reviews highlights of b and c physics for the linear collider programs and the directions of ongoing R&D on pixellated Si sensors for its vertex tracker.
The prospects of the future PANDA experiment at FAIR in Darmstadt/Germany in the field of charmonium and charm spectroscopy are discussed.
We report on the first observation of open charm production in neutral current deep inelastic neutrino scattering as seen in the NuTeV detector at Fermilab. The production rate is shown to be consistent with a pure gluon-$% Z^{0}$ boson production model, and the observed level of charm production is used to determine the effective charm mass. As part of our analysis, we also obtain a new measurement for the proton-nucleon charm production cross section at $\sqrt{s}=38.8$ GeV.
Progress in charm physics has been prodigious over the last twenty years; it comes both from fixed target and collider experiments, and can guide us toward future investigations. To fully exploit the power of flavor physics, complications coming from strong dynamics effects have to be dealt with. The role of charm in the search for New Physics, the lessons learnt so far and warnings for the future are briefly discussed.
We present an idea for a future D0-D0bar mixing and CP violation experiment to run at the Fermilab Tevatron. We estimate that in three years of running, such an experiment could reconstruct an order of magnitude more flavor-tagged D0->K+pi- decays than will be reconstructed by the B-factory experiments with their full data sets. The resulting sensitivity to CP-violating parameters |q/p| and Arg(q/p) is calculated from a global fit to CP-violating observables, and it is found to be much greater than current world sensitivity.
We closed the CHARM 2007 workshop with a lively panel discussion on the future of the field. This document presents a summary of the key points, and a lightly edited transcript of the discussion itself.
We review the most recent results from experiments studying systems containing charmed quarks. The selection reflects the presenter's bias, and there is an emphasis on decays of open charm. We discuss precision measurements of various sorts, various new states in the charmonium system, measurements aimed at testing Lattice QCD, and the latest searches for charm mixing. We conclude with a discussion of upcoming experiments at existing and future facilities.
The "BTeV/C0" experiment at Fermilab could reconstruct >10^9 charm decays, four orders of magnitude beyond the largest extant sample. The experiment is likely to run during Tevatron Run II (ca. 2000--2005). In addition to "programmatic" charm physics such as spectroscopy, lifetimes, and QCD tests, it will have significant new-physics reach in the areas of CP violation, flavor-changing neutral-current and lepton-number-violating decays, and $D^0\bar{D^0}$ mixing, and could observe direct CP violation in Cabibbo-suppressed D decays if it occurs at the level predicted by the Standard Model.
We search for rare FCNC charm decays of the form $X_c^+\to h^+\llp$, where $X_c^+$ is a charm hadron, $h$ is a pion, kaon or proton, and $\ell^{(}{'}^{)}$ is an electron or a muon. In the pion and kaon modes, we study both $D^+$ and $D_s^+$ decays, while in the proton modes we study $Λ_c^+$ decays. Based on a data sample of 288${fb}^{-1}$ of $e^+e^-$ collisions collected by BABAR, we set preliminary 90% confidence level limits between 4 to 40$\times10^{-6}$ for the branching fractions of the different decay modes. For most decay modes, our analysis provides a significant improvement over previ…
Charm physics has been established at the LHC based on several high-precision measurements. The future of charm physics at the LHC experiments is discussed in detail. The bulk of the charm physics programme will be performed by LHCb and the LHCb upgrade. In particular, the impact of the LHCb upgrade on mixing and \CP violation measurements is presented.
Flavor changing neutral currents (FCNCs) in the charm system are highly suppressed in the standard model (SM). The theoretical strategies used to suppress FCNCs induced by supersymmetry in the strange and beauty systems need not apply to the charm system. The charm changing neutral current decay D^0-> mu^+ mu^- is studied phenomenologically in the framework of supersymmetric extensions of the standard model. It is found that the decay branching ratio can be enhanced to about 10^{-10}, by having heavy non-degenerate supersymmetric strange or bottom quarks, with negligible effect on the strange …
In this paper a search for associated charm production both in neutral and charged current $ν$-nucleus interactions is presented. The improvement of automatic scanning systems in the {CHORUS} experiment allows an efficient search to be performed in emulsion for short-lived particles. Hence a search for rare processes, like the associated charm production, becomes possible through the observation of the double charm-decay topology with a very low background. About 130,000 $ν$ interactions located in the emulsion target have been analysed. Three events with two charm decays have been observed in…
We present recent results in the charm sector from the CLEO Collaboration. The data used were collected by the CLEO II and III detectors at the Cornell Electron Storage Ring (CESR). Measurements of form factors and branching fractions in semileptonic decays of D-meson and charmed-baryons, searches for CP violation and rare decays, and Dalitz analyses of D-meson decays are discussed, as well as future plans for the CLEO-c experiment at CESR-c.
One component of the future international Facility for Antiproton and Ion Research - FAIR is directed towards studies of hadronic matter at the sub-nuclear level with beams of antiprotons. These studies focus on two key aspects: confinement of quarks and the generation of the hadron masses. These goals will be pursued by performing precision measurements of charged and neutral decay products from antiproton-proton annihilation in the charmonium mass region. In this report an overview of the charmonium issues relevant to PANDA will be presented.
Current HFAG averages of the mixing and CP violation parameters in the $D^0$ meson system is to be reviewed. We present recent Belle measurements of the mixing parameters $x$ and $y$ using $D^0\rightarrow K^0_Sπ^+π^-$, and $y_{CP}$ and $A_Γ$ from $D^0\rightarrow h^+h^-$, $D^0\rightarrow K^-π^+$, where $h$ denotes $K$ or $π$. Belle measurements of direct CP violation in $D^+\rightarrow K^0_Sπ^+$, $D^0\rightarrow h^+h^-$, and $D^+\rightarrow K^0_SK^+$ decays together with $ΔA^{hh}_{CP}$ are to be presented.
We review status of $R$ measurement and QCD studies at low energy range, discuss prospects for a super $τ-$charm factory in $2-7$ GeV. With a high-luminosity $e^+e^-$ collider, statistics are no longer problem for $R$ measurement and a precision of $2\%$ or even better is foreseen, that will lead to bring down the uncertainty of hadronic contribution to the QED running coupling constant $Δα_{had}$ and the anomalous magnetic moment of the muon ($a_μ$); measure the strong coupling constant $α_s$ and the charm quark mass; improve the measurement of the resonance parameters of heavy charmonia. Hug…
Search for rare charm decays at BESIII
BESIII实验利用最大粲数据样本搜索稀有衰变，涵盖弱衰变、味改变中性流等，未发现显著信号，并设定了多个分支比上限。
We explore the feasibility of the measurement of charm-jet cross sections in charged-current deep-inelastic scattering at the future Electron-Ion Collider. This channel provides clean sensitivity to the strangeness content of the nucleon in the high-$x$ region. We estimate charm-jet tagging performance with parametrized detector simulations. We show the expected sensitivity to various scenarios for strange parton distribution functions. We argue that this measurement will be key to future QCD global analyses, so it should inform EIC detector designs and luminosity requirements.
Charm Lifetimes and Semileptonic Decays
本文综述了粲寿命和半轻子衰变的实验研究现状和有待解决的问题，后者包括E687和CLEO在这次会议上提出的新结果。
Charm2000: A >10^8-charm experiment for the turn of the millennium
我讨论了一个固定目标粲实验的物理范围，它可以重建>10^8个粲衰变，比现存最大的样本高出三个数量级。这样的实验可能在2000年后不久在费米实验室进行。除了光谱学、寿命和QCD测试等“程序化”的魅力物理学之外，“魅力2000”实验还将对CP破坏、变味中性流和轻子数破坏衰变以及混合等领域的新物理学具有显著的敏感性，并可以在标准模型预测的水平上观察到卡比博抑制衰变中的直接CP破坏。
We review current experimental results on charm mixing and CP violation. We survey experimental techniques, including time-dependent, time-independent, and quantum-correlated measurements. We review techniques that use a slow pion tag from D*+ --> pi+ D0 + c.c. decays and those that do not, and cover two-body and multi-body D0 decay modes. We provide a summary of D-mixing results to date and comment on future experimental prospects at the LHC and other new or planned facilities.
The framework of the expansion by subgraphs is used to compute asymptotic expansions for the vector and the tensor currents in the limit of large quark masses. We use the results to obtain an estimate for the influence of heavy quarks on the nucleon electromagnetic and tensor form factors.
The nuclear emulsion target of the CHORUS detector was exposed to the wide-band neutrino beam of the CERN SPS of 27 GeV average neutrino energy from 1994 to 1997. In total about 100000 charged-current neutrino interactions with at least one identified muon were located in the emulsion target and fully reconstructed, using newly developed automated scanning systems. Charmed particles were searched for by a program recognizing particle decays. The observation of the decay in nuclear emulsion makes it possible to select a sample with very low background and minimal kinematical bias. 2013 charged-…
Can millicharge be probed at future Super Tau Charm Facility via mono-$π^0$ searches?
本研究提出在未来超级陶粲装置上通过单$\pi^0$ 信号搜寻微电荷粒子的新通道，计算了信号与标准模型本底事例，推导了不同能量下的微电荷上限，指出该方法在低质量区有一定提升，可作为不可见粒子研究的补充。
This review will present the future prospects for physics at electron-positron colliders running near the Upsilon(4S) as well as at the charm and tau thresholds. It includes a review of the Belle II and SuperB projects. Also reviewed are the plans for BES III, which operates near the charm threshold at the IHEP BEPC machine in Bejing and the status of the Super Charm/Tau Factory proposed for the Budker Institute for Nuclear Physics (BINP) in Novosibirsk.
The physics of tau and charm started in early 70's after J/$ψ$ and $τ$ were discovered. Since then several dedicated accelerators and experiments were built with increasing luminosities and studies on light hadron spectroscopy, charmonium, electroweak and QCD were never interupted. New interests and surprises are not rare in this area. With the newly built BEPCII/BESIII, an even brighter future is foreseen.
We review the current status of flavor-changing neutral currents in the charm sector. We focus on the standard-model predictions and identify the main sources of theoretical uncertainties in both charm mixing and rare charm decays. The potential of these observables for constraining short-distance physics in the standard model and its extensions is compromised by the presence of large nonperturbative effects. We examine the possible discovery windows in which short-distance physics can be tested and study the effects of various extensions of the standard model. The current experimental situati…
We review some recent developments in charm meson physics. In particular, we discuss theoretical predictions and experimental measurements of charmed meson decays to leptonic, semileptonic, and hadronic final states and implications of such measurements to searches for new physics. We discuss D0-anti-D0-mixing and CP-violation in charm, and discuss future experimental prospects and theoretical challenges in this area.
We shed new light on the standard current algebra approach to the nonleptonic two-body decays of single and double heavy charm baryons. By making use of the completeness relation for the flavor wave functions of the ground state baryon {\bf 20'} representation we are able to rewrite the results of the current algebra approach in terms of the seven topological tensor invariants describing the decays. The representation of the current algebra results in terms of topological tensor invariants depends only on the initial and final state of the process. The summation over intermediate states inhere…
The CLEO Collaboration recently has announced the discovery of an excited charmed and strange baryon. We estimate the expected width of this new member of the Xi_c family. We discuss the phenomenology of the excited csq and css states, and consider what additional charmed baryons might be observable in the future. We point out that the final state Xi_c + K could be an interesting new channel to examine.
Indirect searches, and in particular rare decays, have proven to be a fruitful field to search for New Physics beyond the Standard Model. While the down-quark sector (B and K) have been studied in detail, less attention was devoted to charm decays due to the smaller expected values and higher theoretical uncertainties of their observables. Recently a renewed interest is growing in rare charm searches. In this article we review the current experimental status of searches for rare decays in charmed hadrons. While the Standard Model rates are yet to be reached, current experimental limits are alr…
The present data imply that $ϕ(2170)$ may not be an excited state of $ϕ$, but is a four quark state with $ss\bar s \bar s$ constituents. Furthermore, there are no two mesons of $s\bar s$ available to form a molecule which fits the mass spectrum of $ϕ(2170)$, thus we suggest it should be an $ss\bar s \bar s$ tetraquark state. In this scenario, we estimate its decay rates through the fall-apart mechanism. Our theoretical estimates indicate that its main decay modes should be $ϕ(2170)$ into $ϕf_0(980)$, $ h_1η$, $ h_1η'$, $K_1(1270)K$ and $K_1(1400)K$. Under this hypothesis the modes $ϕ(2170)\to …
$Ξ_{cc}^{++}-Ξ_{cc}^{+}$ Transitions as a Two-Charm-Selective Portal to Ultra-Low-$Q$ Charged Currents
本文利用LHCb观测到的$\Xi_{cc}^{+}$，提出$\Xi_{cc}^{++}\to\Xi_{cc}^{+}$超低$Q$跃迁作为带电电流新物理的零检验，通过两体和三体分析展示了对MeV尺度反冲动量下有效重子能级耦合的灵敏度，并识别出双粲选择性带电电流门户。
Charmonium is a bound state of a charmed quark and a charmed antiquark, and a charmoniumlike state is a resonant structure that contains a charmed quark and antiquark pair but has properties that are incompatible with a conventional charmonium state. While operating at center-of-mass energies from 2 to 4.9 GeV, the BESIII experiment can access a wide mass range of charmonium and charmoniumlike states, and has contributed significantly in this field. We review BESIII results involving conventional charmonium states, including the first observation of M1 transition $ψ(3686) \to γη_c(2S)$ and the…
Abundance of charm data in the current and future low energy flavor experiments makes it possible to study rare decays of D-mesons with ever increased precision. I discuss theoretical implications of derived constraints on New Physics models from these transitions. I argue that those constraints could be competitive with results of direct searches for New Physics particles (including Dark Matter) at the Large Hadron Collider.
We present an overview of recent developments in charm physics reported in the Working~Group~7 meetings of the CKM 2016 workshop. Progresses in experimental analysis and techniques were reported by LHCb, Belle, BABAR and BESIII along with projections for the future. Developments were also reported in the phenomenological extraction of both direct and indirect CP violation from data in two-, three- and four-body hadronic decays of the $D$ mesonic system.
High-Impact Charm Physics at the Turn of the Millennium
我审查的灵敏度所取得的和预计的固定目标的魅力实验在CP破坏，口味改变中性流和轻子数违反衰变，和混合，我描述的魅力2000年的实验打算运行在费米实验室在2000年。如果获得批准，Charm 2000将在许多这些领域超过Tau/Charm工厂的敏感度，但Tau/Charm工厂保留了某些质量优势。
We propose a new variable, the charm fraction, for collider searches for new physics. We analyze this variable in the context of searches for simplified supersymmetry models with squarks, the gluino, and the bino, assuming that only the lightest mass-degenerate squarks can be produced at the high-luminosity LHC. The charm fraction complements event counting and kinematic information, increasing the sensitivity of the searches for models with heavy gluinos, for which squark production is flavor-blind. If squarks are discovered at the LHC, this variable can help discriminate between different un…
High-precision flavor physics measurements play a complementary role to the direct searches for new physics by CMS and ATLAS experiments at LHC. Such measurements will be performed with the Belle II detector at the upgraded KEKB accelerator (SuperKEKB) in Japan. The physics potential with emphasis on the charm sector, current status and future prospects of the Belle II experiment are presented in these proceedings.
We describe a new technique (presented in arXiv:1403.1778) to determine the contribution to the anomalous magnetic moment (g-2) of the muon coming from the hadronic vacuum polarisation using lattice QCD. Our method uses Padé approximants to reconstruct the Adler function from its derivatives at $q^2=0$. These are obtained simply and accurately from time-moments of the vector current-current correlator at zero spatial momentum. We test the method using strange quark correlators calculated on MILC Collaboration's $n_f$ = 2+1+1 HISQ ensembles at multiple values of the lattice spacing, multiple vo…
We introduce the contributions to the proceedings of Working Group V. The main topics were: present and future experiments dedicated to charm physics, the interplay between high-precision measurements and better control over theoretical uncertainties, and searches for signals of new physics in the charm sector. The comparison of Lattice QCD calculations with precise measurements of charm semi-leptonic and leptonic decays can have a major impact on the determination of CKM matrix elements from measurements of B meson decays.
Photoproduction of the $X(3872)$ beyond vector meson dominance: the open-charm coupled-channel mechanism
针对未来电子-离子对撞机的隐粲奇特强子研究，提出考虑开粲介子-重子中间态的耦合道机制，估算$\gamma p\to X(3872)p$反应截面为数十纳靶恩，其独特线形可用于揭示产生动力学。
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