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...
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...
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...
$CP$ 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...
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...
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...
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...
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...
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) ...
n this talk, four recent measurements of chi_cJ or psi decays at BESIII will be presented. In contains: 1) Using 448 million psi(3686) events collected with the BESIII detector, the process psi(2S) -> phi Ks Ks has been observed for the first time, and the branching fraction is determined; 2) Using the same data sample, the branching fractions of the decays chi_cJ -> phi phi (J=0,1,2) have...
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 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...
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...
LHCb has played a major role in charm physics over the last years analysing data recorded during Run I and Run II. Recently, the LHCb detector has undergone a series of major upgrades. This talk will include the first performance results from the new LHCb detector in Run III and a brief look into the future charm physics program of the collaboration.
