We consider theoretical frameworks used in charm physics.
First, we briefly review the approaches and results of the Standard Model used in the
processes with the charm quark.
Then we discuss possibilities to search for a theory behind the Standard Model.
The talk will set the scene for the experimental reports of the programme. The various scientific topics will be mapped out with brief individual introductions touching on the respective main features. A zoomed-out view will (attempt to) arrange the pieces into an overall picture, spanning the past, present and future. Experimental methods will be examined through the lens of their advantages,...
In the last few years, $D^0 - \overline{D^0}$ mixing has become a true benchmark for the Standard Model thanks to the precision reached by modern experiments. Charm mixing may reveal signals of heavy New Physics since it happens through Flavour Changing Neutral Currents, which are absent at the tree level and GIM-suppressed at the loop level in the Standard Model.
The most promising...
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 mixing of neutral $D$ mesons is the least understood of all neutral meson mixing processes. Both in experiment and theory, the mixing of $K, B, B_s$ mesons is known to a much higher precision. In this talk I will present results of a lattice calculation on the short-distance contribution to $D$-meson mixing, whose matrix elements are important inputs for various models beyond the Standard...
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...
We study the inclusive decay widths of the singly heavy baryon using the improved bag model in which the unwanted center-of-mass motion is removed. We discuss the running of the baryon matrix elements and compare the results with the non-relativistic quark model (NRQM). We find that while the numerical values of two-quark operator elements are compatible with the literature, those of the...
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 ->...
$CP$ violation in charm decays is predicted to be very small, only $\sim\!10^{-3}$ or less. Thus, observing significant $CP$ violation could indicate new physics beyond the Standard Model. The Belle experiment has searched for $CP$ violation in charm decays by measuring an asymmetry about zero for the $T$-odd triple product $\vec{p}^{}_1\cdot (\vec{p}^{}_2\times \vec{p}^{}_3)$, where...
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...
The Kobayashi-Maskawa (KM) mechanism predicts that a single parameter must be responsible for CP-violating phenomena in different quark flavour sectors of the Standard Model (SM). Despite this minimal picture, challenged by non-SM physics, the KM mechanism has been so far verified in the bottom and strange sectors, but lacks tests in the complementary charm sector. For the sake of this, urgent...
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%...
We will review the latest theoretical predictions of charmed meson and baryon lifetimes and will summarize the status of D-Dbar mixing in the Standard Model.
Charm physics, involving a heavy up-type quark, offers a pathway to search for new particles and couplings beyond the Standard Model complementary to that of B physics. A program based on precision measurements of charm lifetimes is now underway at Belle II, and benefits from the detector's outstanding vertexing performance and low-background environment. Recent results from measurements of...
LHCb has collected the world's largest sample of charmed hadrons. This sample is used to measure $D^0 -\overline{D}^0$ mixing, search for $C\!P$ violation in mixing and interference and measurements of charm-baryon lifetimes. New measurements from several decay modes are presented, as well as prospects for future sensitivities.
Spectroscopy studies on the lattice can provide valuable
insights through the investigation of states that are not well established experimentally, through the prediction of new states and by testing theoretical descriptions. The internal structure of these states can, in principle, be probed by determining their decay constants, form factors and so on. Mesons and baryons containing heavy...
Charmed meson and baryon spectroscopy gives insight into QCD at low energies from a unique perspective. Recently, the discovery of many previously unobserved charmed states and precise measurements of their properties have been made. This talk reports the latest work on the spectroscopy of charmed hadrons at LHCb and other key experiments in the field.
A recently proposed modification to the widely used distillation framework yields a substantial improvement in the calculation of the spectrum of charmonium with different $J^{PC}$ at almost no additional computational cost compared to the standard distillation framework. This improved variant is now used to calculate the charmonium spectrum in an $N_f = 3 + 1$ ensemble at the SU(3) light...
In recent years, BESIII has accumulated tens of 1/fb electron-positron colliding data samples at cms energies from 4 to 5 GeV. Cross-section measurements are performed with specific final states to search for vector charmonium(-like) states. I shall present three corresponding recent results in this talk. It includes: 1) cross-sections of e+ e- -> Ks Ks J/psi from 4.13 to 4.95 GeV, in which...
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...
A baryon-antibaryon pair from electron-positron annihilation is a simple spin entangled system that can be used for studies of time-like electromagnetic form factors, baryon decays and test of discrete symmetries.
A modular approach [Phys.Rev.D 99 (2019) 056008] where the complete angular distributions in such processes are conveniently obtained using products of real-valued matrices...
We study charmonia in heavy ion collisions by focusing on the production of charmonium states from charm and anti-charm quarks in a quark-gluon plasma by recombination. Starting from the investigation on the internal structure, or the wave function of charmonium states we discuss the yield and transverse momentum distributions of charmonium states produced in heavy ion collisions. We argue...
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 $D\to\bar{K}\pi\pi$...
Under some assumptions on the hierarchy of relevant energy scales, we compute the nonrelativistic QCD (NRQCD) long-distance matrix elements (LDMEs) for inclusive production of J/ψ, ψ(2S), and Υ states based on the potential NRQCD (pNRQCD) effective field theory. Based on the pNRQCD formalism, we obtain expressions for the LDMEs in terms of the quarkonium wavefunctions at the origin and...
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...
Precise measurements of the lepton properties provide stringent tests of the Standard Model. The large mass of the tau makes also possible to perform accurate QCD studies and search for violations of lepton flavour in many kinematically-allowed decay modes. The present status of tau physics and the prospects for future improvements will be discussed.
The proposed STCF is a symmetric electron-positron beam collider designed to provide e+e− interactions at a centerof-mass energy from 2.0 to 7.0 GeV. The peaking luminosity is expected to be 0.5×10^35 cm−2s−1. STCF is expected to deliver more than 1 ab−1 of integrated luminosity per year. The huge samples could be used to make precision measurements of the properties of XYZ particles; search...
A nonperturbative charm production contribution, known as intrinsic charm, has been speculated since the 1980s. While it has yet to be satisfactorily proven, there have been recent tantalizing hints. Several experiments, either taking data or planned, could proivde definitive evidence in the next few years. Recent experiments that have taken $J/\psi$ and $D$ meson data include SeaQuest at...
The J\$\psi$ meson, discovered simultaneously in 1974 at Brookhaven National Laboratory and the Stanford Linear Accelerator, remains a focus of great interest today to physicists worldwide. J/$\psi$ analyses are published regularly in heavy-ion physics that range from elliptic flow in $p$A and AA collisions to ratios of J/$\psi$ and its excited state the $\psi$(2S), as well as...
The theoretical description for charm decays is notoriously challenging. In this respect, semi-leptonic decays are excellent probes as they are at least easier to describe than their nonleptonic counterparts. In this talk, I will focus on inclusive semi-leptonic charm decays. For these decays, one may hope that the heavy-quark expansion, a well-established tool in beauty decays, works to some...
LHCb is playing a crucial role in the study of rare and forbidden decays of charm hadrons, which might reveal effects beyond the Standard Model. This talk presents the latest searches for and measurements using rare charm decay processes with leptons in the final state.
In this review talk, I will present the status of lattice calculations of semileptonic decays of charmed hadrons. I will review results from different collaborations and discuss how they lead to quantities of phenomenological relevance, including decay rates, CKM matrix elements, and lepton flavor universality ratios.
In this report, I mainly overview the recent selected leptonic and semileptonic decays of charmed hadrons including D0, D+, Ds and L_c(L=Lambda), based on data samples collected by BESIII detector corresponding to luminosities of 2.93 fb-1, 7.33 fb-1 and 4.5 fb-1 above the threshold of DDbar, DsDs* and LcLcbar, respectively. By measuring the branching fractions , form factors and CKM matrix...
The analyses of states with double cs content and the search for exotics have recently gained much attention. The Belle experiment collected roughly 1 ab-1 integrated luminosity data. While Belle II data-taking is in progress, we have performed a new search for exotic states and cross-section measurements with the full Belle data sets. Here we review the recent analysis of:
a) ...
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.
Spectroscopy in the iso-scalar channels that contain charmonia, glueballs, light mesons and multi-particle states, poses a big challenge for lattice QCD calculations. One of the reasons is the presence of notoriously noisy and expensive quark-disconnected contributions to the correlation functions. We present modern techniques, based on "distillation", which allow us to investigate the...
We study the time evolution of the number of charm mesons after the kinetic freeze-out of the hadron gas produced by a central heavy-ion collision. The $\pi D^*\to \pi D^*$ reaction rates have t-channel singularities that give contributions inversely proportional to the thermal width of the $D$. The ratio of the $𝐷^0$ and $𝐷^+$ production rate can differ significantly from those predicted...
We study charmonium and glueballs on $N_f=3+1$ lattice ensembles using distillation as a smearing for the quark fields. The novelty of our study is the inclusion of light hadrons into which these states can decay. We present preliminary results for the hyperfine splitting of the low-lying charmonium states by including disconnected diagrams together with light flavor mixing.
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...
The recent BESIII data on $J/\psi\to\gamma(K_SK_S\pi^0)$, which is significantly more precise than earlier $\eta(1405/1475)$-related data, enables quantitative discussions on $\eta(1405/1475)$ at the previously unreachable level. We conduct a three-body unitary coupled-channel analysis of experimental Monte-Carlo outputs for radiative $J/\psi$ decays via $\eta(1405/1475)$: $K_SK_S\pi^0$ Dalitz...
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...
Charm physics, involving a heavy up-type quark, offers a pathway to search for new particles and couplings beyond the Standard Model complementary to that of B physics. Measurements of CP violation and mixing play a key role in this program. We present a novel algorithm that identifies the flavor of neutral charm mesons at the time of production. This algorithm effectively doubles the sample...
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...
Direct CP violation in the charm sector
LHCb has collected the world's largest sample of charm hadrons. This sample is used to measure direct $C\!P$ violation in $D$ mesons and charm baryons. The latest measurements from several decay modes are presented, as well as prospects for future sensitivities.
For charmed mesons, this presentation will report the recent amplitude analyses of Cabibbo-favored and -suppressed Ds decays by BESIII, including the observation of a new a0-like state at 1.817 GeV, the branching fraction measurements of D meson doubly Cabibbo-suppressed decay and decays involving KL0. In addition, LHCb recently performed many measurements of CP violation/asymmetry and...
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