We study rare charm decays with missing energy to probe light degrees of freedom.
Specifically, we investigate axion-like particles and light $Z^\prime$ bosons with dark fermions.
We also consider EFT models with light neutrinos of both chiralities.
Observables of both charm mesons and baryons are examined to assess their sensitivity and potential to probe NP.
We find that the missing...
The BESIII experiment is a symmetric e+e- collider operating at c.m. energy from 2.0 to 4.95 GeV. With the world’s largest data set of J/psi (10 Billion), psi(2S) (2.6 Billion), and about 25 fb-1 scan data from 3.77 to 4.95 GeV, we are able to search various dark sectors produced in e+e- annihilation and meson decay processes. In this talk, we report the search for dark photon candidate in...
Currently, it is not clear whether the observed level of CP violation in the charm system can be accommodated within the SM, and further measurements are needed. Multi-body charm decays are powerful tools to search for CP violation through interference of intermediate resonances which may lead to local asymmetries in the phase space. LHCb is successfully exploring model-independent approaches...
The BESIII experiment has collected 2.6B psi(2S) events and 10B J/psi events. The huge data sample provide an excellent chance to search for rare processes in charmonium and charm meson decays. In this talk, we report the recent search for J/psi->D^-e+nu_e, psi(2S)->Lambda_c anti-Sigma^-. In addition, LFV process J/psi->e tau/e mu & BNV/LNV process D^0->p e/n e, and the FCNC process D^0 ->...
We present constraints on the left-handed dimension-6 interactions that contribute to semileptonic and leptonic decays of $K$, $D$, pions and to nuclear beta decay. We employ the flavour covariant description of the effective couplings, identify universal CP phases of New Physics and derive constraints from decay rates and CP-odd quantities. As a result, we can predict the maximal effects of...
At BESIII, the R value is measured with a total of 14 data points with the corresponding c.m. energy going from 2.2324 to 3.6710 GeV.
The statistical uncertainty of the measured R is less than 0.6%. Two different simulation models, the LUARLW and a new Hybrid generated, are used and give consistent detection efficiencies and initial-state-radiation corrections. An accuracy of better than 2.6%...
BESIII has collected 2.93 and 7.33 fb$^{-1}$ of $e^+e^-$ collision data samples at 3.773 and 4.128-4.226 GeV, which provide the largest dataset of $DD^-$ and $D_s D_s$ pairs in the world, respectively.
In this talk, we will report the updated measurements of $|V_{cs}|$ in $D^+_s\to \tau^+\nu$ and the form factor studies in $D^+_s\to K^+K^- e^+\nu$ and $\pi^+\pi^-e^+\nu$. In addition, we will...
We present results from our calculation of decays rates for $\eta_c\to\gamma\gamma$, $J/\psi\to\gamma\eta_c$ and $J/\psi\to\eta_c e^+e^-$ in lattice QCD with the effect of u, d, s and c quarks in the sea for the first time. We use the Highly Improved Staggered Quark formulism, four values of the lattice spacing and sea u/d quarks down to their physical values. Our results are accurate at the...
Rare charmed meson decays are a promising canvas for New Physics signatures to appear, being by definition very suppressed in the SM and since previous studies have identified observables that are free from SM contributions. In light of the extended amount of recently released LHCb data, a better control over the SM dynamics is imperative for a comparison to the experimental observables and...
We discuss some applications of isospin symmetry in the
Cabibbo favoured $D\to\bar{K}\pi\pi$ decays. These processes are important for
precision testing of the Standard Model and for hadronic physics. Combining
isospin symmetry with a dispersive reconstruction theorem we derive a
representation in terms of one-variable functions which allows one to predict
all the $D\to\bar{K}\pi\pi$...
We study the effects of $D^0$-$\bar{D}^0$ mixing and CP violation in $D^0 \to K^{*\pm} K^{\mp}$ decays and their CP-conjugated processes. We find that both the $D^0$-$\bar{D}^0$ mixing parameters and the strong-interaction phase difference between $\bar{D}^0 \to K^{*\pm}K^{\mp}$ and $D^0 \to K^{*\pm}K^{\mp}$ transitions can be determined from the time-dependent measurements of these decay...
We present a novel unbinned method to combine B --> DK and charm threshold data for the amplitude-model unbiased measurement of the CKM angle gamma in cases where the D meson decays to a three-body final state. The new unbinned approach avoids any kind of integration over the D Dalitz plot, to make optimal use the available information. We verify the method with simulated signal data where the...
The distribution amplitudes (DAs) are the universal non-perturbative elements that enter the description of processes involving strong interactions in frameworks like light cone sum rules (LCSR). For light quark systems, they are formulated using the properties of conformal symmetry. However, for heavy quark systems, one faces different challenges. The most important quantities of interest for...
We investigate the renormalization properties of the shape function formalism for inclusive production of $P$-wave heavy quarkonia, which arises from resumming a class of corrections coming from kinematical effects associated with the motion of the heavy quark and antiquark pair relative to the quarkonium. Such kinematical effects are encoded in the nonperturbative shape functions, which are...
In this presentation i will first talk about the recent QCD LCSRs calculation of $D_s^\ast \to \phi$ helicity form factors and discuss the experiment potential of discovering exclusive $D_s^\ast$ weak decays, then i will discuss the width effect in the $D_s \to f_0 (\to \pi^+\pi^-) l\nu$ decay.
The light-cone distribution amplitudes of two-pion states are universal hadronic objects involved in the factorization of heavy hadron decays or in the large momentum-transfer transitions with two pions in the final state. The leading twist-2 distribution amplitudes are parameterized in terms of the functions of the dipion invariant mass serving as coefficients in the Gegenbauer expansion....
Using the world’s largest samples of J/psi and psi(3686) events produced in e+e- annihilation, BESIII is uniquely positioned to study light hadrons in radiative and hadronic charmonium decays. In particular, exotic hadron candidates including multiquark states, hybrid mesons and glueballs can be studied in high detail. Recent highlights on the light exotics searches, including the observation...
The LHCb collaboration announced in 2021 the discovery of a new tetraquark-like state, named $T_{cc}^+$. The $T_{cc}^+$ is reminiscent of the $X(3872)$, which is a candidate for a loosely-bound $D\bar D^*$+h.c. molecule; however, we are now dealing with an open-charmed state which radically changes its nature and makes it explicitly exotic. In this talk, the recently discovered $T_{cc}^+$ is...
In 2022, doubly charmed baryon hadronic weak decay Ξ_cc^{++}→Ξ_c^('+) π^+ was first observed by LHCb and its branching fraction relative to Ξ_cc^{++}→Ξ_c+ π+ was reported. In this talk we will introduce the study of charmed baryon decays Ξ_cc^{++}→Ξ_c^('+) π^+ within the framework of the nonrelativistic quark model (NRQM). Factorizable amplitudes in terms of transition form factors, while...
BESIII has collected 4.5 fb^-1 of e+e- collision data between 4.6 and 4.7 GeV. This unique data offers ideal opportunities to study Lambda_c+ decays. We will report the partial wave analysis of Lambda_c+ -> Lambda pi+ pi0 and the observations of Cabibbo-suppressed Decays Lambda_c+ decays, including Λ+c → nπ+ etc. In addition, we will report the form factor measurement in Lambda_c+ -> Lambda e+...
Three decades ago, heavy-flavor-conserving (HFC) weak decays of heavy baryons such as $\Xi_Q\to\Lambda_Q\pi$ and $\Omega_Q\to\Xi_Q\pi$ for $Q=c,b$ had been studied
within the framework that incorporates both heavy-quark and chiral symmetries.
HFC decays have two great advantages: (1) S-wave can be evaluated reliably using current algebra, and (2) if the heavy quark in the HFC process behaves...
