Charm mixing and CP violation observables are examined in the light of the recently reported evidence from LHCb for CP violation in the charm sector. If the result is confirmed as being due to direct CP violation at the 1% level, its effect will need to be taken into account in the interpretation of CP violation observables. The contributions of direct and indirect CP violation to the decay rate asymmetry difference DeltaACP and the ratios of effective lifetimes AGamma and yCP are considered here. Terms relevant to the interpretation of future high precision measurements which have been neglected in previous literature are identified.
We derive indirect limits on the charm and bottom quark electric dipole moments (EDMs) from paramagnetic AMO and neutron EDM experiments. The charm and bottom quark EDMs generate $CP$-odd photon-gluon operators and light quark EDMs at the $c$- and $b$-quark mass thresholds. These $CP$-odd operators induce the $CP$-odd semi-leptonic operator $C_S$ and the neutron EDM below the QCD scale that are probed by the paramagnetic and neutron EDM experiments, respectively. The bound from $C_S$ is $\vert d_c \vert < 1.3\times 10^{-20}\,e\,\mathrm{cm}$ for the charm quark and $\vert d_b \vert < 7.6\times …
The LHCb experiment collected during run I the world's largest sample of charmed hadrons. This sample is used to search for CP violation in charm and for the measurements of D0 mixing parameters. The measurement of the D0 to D0bar mixing parameters and the search for indirect CP-violation in two-body charm decays at LHCb experiment are presented.
The potentiality of interpreting the D-meson decay-dynamics has revealed itself to be strongly dependent on our understanding of the light-meson sector. The statistics collected by FOCUS is already at a level that manifests parametrization problems for scalar particles. In this paper the first application of the K-matrix approach in the charm sector is illustrated and preliminary results on the D+ and Ds decays to three pions are shown.
We summarize recent results for charm physics. These results span several categories: charm mixing, indirect (time-dependent) CP violation, direct (time-integrated) CP violation, T violation, semileptonic and leptonic decays, and decays of charm baryons.
LHCb has collected the world's largest sample of charmed hadrons. This sample is used to search for direct and indirect CP Violation in charm. Recent and updated measurements from several decay modes are presented.
Time-dependent studies of inclusive charm decays to multibody self-conjugate final states can be used to determine the indirect $CP$-violating observable $A_Γ$ and the mixing observable $y_{CP}$, provided that the fractional $CP$-even content of the final state, $F_+$, is known. This approach can yield significantly improved sensitivity compared with the conventional method that relies on decays to $CP$ eigenstates. In particular, $D \to π^+π^-π^0$ appears to be an especially powerful channel, given its relatively large branching fraction and the high value of $F_+$ that has recently been meas…
Studies of rare decays are an indirect probe of New Physics (NP). This document presents recent measurements of rare decays in the charm sector by the LHCb experiment. The analyses are performed with proton-proton collision data at $\sqrt{s}$ = 7 TeV recorded in 2011.
We discuss the determination of the CKM angle $α$ using the non-leptonic two-body decays $B\to ππ$, $B\to ρρ$ and $B\to ρπ$ using the latest data available. We illustrate the methods used in each case and extract the corresponding value of $α$. Combining all these elements, we obtain the following determination of $α_{\rm dir}=( 86.2^{+4.4}_{-4.0}~~ \cup~~ 178.4^{+3.9}_{-5.1})^\circ$. We assess the uncertainties associated to the breakdown of the isospin hypothesis and the choice of statistical framework in detail. We also determine the hadronic amplitudes (tree and penguin) describing the QCD…
LHCb has collected the world's largest sample of charmed hadrons. This sample is used to search for direct and indirect CP violation in charm and to measure $D^0$ mixing parameters. Preliminary measurements from several decay modes are presented, with complementary time-dependent and time-integrated analyses.
The current status of the search for indirect CP violation in the neutral D meson system at the B-factories and at LHCb is reported. The indirect CP asymmetry search is performed by the measurement of the proper-time asymmetry ($A_Γ$) in decays of $D^0-\bar{D^0}$ mesons to CP eigenstates, $K^-K^+$ and $π^- π^+$, and by $y_{CP}$, the ratio between the effective lifetime measured in decay to a CP eigenstate and that to the mixed eigenstate $K π$. All results are consistent with the no CP violation hypothesis. The latest world averages for mixing and CP asymmetry in the charm sector evaluated by …
In this proceedings we present a measurement of mixing, and searches for direct and indirect CP asymmetries in the charm sector using the full \babar data sample of $469 \invfb$. Searches for direct CP asymmetries have been performed in the $D^{\pm} \to K^0_{\scriptscriptstyle S} K^\pm$, $D_s^{\pm} \to K^0_{\scriptscriptstyle S} K^\pm$, $D_s^{\pm}\to K^0_{\scriptscriptstyle S} π^\pm$, and $D^{\pm} \to K^+ K^- π^\pm$ decay channels, with both model-dependent and model-independent approaches being exploited for the last mode. The mixing measurement and the search for indirect CP asymmetry have b…
A first measurement of \fplus, the \CP-even content of the decay D->4pi using decays of $ψ(3770)$ to quantum correlated $D\bar{D}$ decays collected by the CLEO-c experiment is presented. The measured value is \fplus=$0.737 \pm 0.028$. This relatively high value makes the decay mode particularly suitable for both measurements of the CKM angle $γ$ and charm \CP-violation in a model independent way. This novel approach to studying indirect \CP-violation in charm decays is based on the time-dependent inclusive analysis of multi body self-conjugate states. These final states can be used to determin…
LHCb continues to expand its world-leading sample of charmed hadrons collected during LHC's Run 1 (2010-2012) and Run 2 (2015-present). This sample is yielding some of the most stringent tests of the Standard Model understanding of charm physics. This includes precise measurements of the neutral D-meson mixing parameters and some of the most sensitive searches for direct and indirect CP violation in charm interactions.
During run I, the LHCb experiment at the LHC, CERN, collected 1.0 fb$^{-1}$ of pp collisions at $\sqrt{s} = 7$ TeV and 2.0 fb$^{-1}$ at $\sqrt{s} = 8$ TeV, yielding the world's largest sample of decays of charmed hadrons. This sample is used to search for direct and indirect CP violation in charm and to measure $D^{0}$ mixing parameters. Recent measurements from several complementary decay modes are presented.
A summary of the results of several recent studies of charm mixing is presented. A number of different methods were used, including the measurement of lifetime ratios for final states of different CP, time dependence of wrong-sign hadronic decays, fits to time-dependent Dalitz plots, and searches for wrong-sign semi-leptonic decays. Taken together, they suggest mixing is of order 1%. The status of searches for indirect CP violation is also reported.
LHCb has collected the world's largest sample of charmed hadrons. This sample is used to measure the mixing parameters in the $D^0$-$\bar{D}^0$ system and to search for indirect $CP$ violation. This contribution focuses on measurements of $A_Γ$ with $D^*$ and semileptonic $B$ decays and on mixing measurements and a search for $CP$ violation in $D\to Kπ$ decays.
The role of charm in testing the Standard Model description of quark mixing and CP violation through measurements of lifetimes, decay constants and semileptonic form factors is reviewed. Together with Lattice QCD, charm has the potential this decade to maximize the sensitivity of the entire flavor physics program to new physics. and pave the way for understanding physics beyond the Standard Model at the LHC in the coming decade. The status of indirect searches for physics beyond the Standard Model through charm mixing, CP-violation and rare decays is also reported.
We calculate the time-dependent and time-integrated decay rates of $(D^0\bar{D}^0)\rightarrow (K^{\pm}π^{\mp})(l^{\pm}X^{\mp})$ at the $ψ(3.77)$ and $ψ(4.14)$ resonances. The possibilities to distinguish between the effects of $D^0-\bar{D}^0$ mixing and doubly Cabibbo suppressed decay (DCSD) are illustrated, and the signal of $CP$ violation induced by the interplay of mixing and DCSD is discussed. Ratios of the decay rates of $(D^0\bar{D}^0)\rightarrow (K^{\pm}π^{\mp})(K^{\pm}π^{\mp})$ to that of $(D^0\bar{D}^0)\rightarrow (K^+π^-)(K^-π^+)$ are also recalculated by accommodating $CP$ violation…
We present charm CP violation and mixing measurements at Belle. They are the first observation of $D^0-\bar{D}^0$ mixing in $e^+e^-$ collisions from $D^0\rightarrow K^+π^-$ decays, the most precise mixing and indirect CP violation parameters from $D^0\rightarrow K^0_Sπ^+π^-$ decays, and the time-integrated CP asymmetries in $D^0\rightarrowπ^0π^0$ and $D^0\rightarrow K^0_Sπ^0$ decays. Our mixing measurement in $D^0\rightarrow K^+π^-$ decays excludes the no-mixing hypothesis at the 5.1 standard deviation level. The mixing parameters $x=(0.56\pm0.19^{+0.03+0.06}_{-0.09-0.09})%$, $y=(0.30\pm0.15^{…
Recent results on mixing, CP violation and rare decays in charm physics from the LHCb experiment are presented. Study of ''wrong-sign'' $D^{0} \rightarrow K^+ π^-$ decays provides the highest precision measurements to date of the mixing parameters $x^{\prime 2}$ and $y^{\prime}$, and of CP violation in this decay mode. Direct and indirect CP violation in the $D^0$ system are probed to a sensitivity of around $10^{-3}$ using $D^0 \rightarrow K^+K^-$ and $D^0 \rightarrow π^+π^-$ decays and found to be consistent with zero. Searches for the rare decays $D^+_{(s)} \rightarrow π^+μ^+μ^-$, $D^+_{(s)…
D^0-\bar{D}^0 mixing at the detectable level or significant CP violation in the charm system may strongly signify the existence of new physics. In view of the large discovery potential associated with the fixed target experiments, the B-meson factories and the τ-charm factories, we make a further study of the phenomenology of D^0-\bar{D}^0 mixing and CP violation in neutral $D$-meson decays. The generic formulas for the time-dependent and time-integrated decay rates of both coherent and incoherent D^0\bar{D}^0 events are derived, and their approximate expressions up to the second order of the …
Using the full data sample collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider, we present CP violation in charm decays. The $D^0-\bar{D}^0$ mixing parameter $y_{CP}$ and indirect CP violation parameter $A_Γ$ in $D^0\rightarrow h^+h^-$ decays are reported, where $h$ denotes $K$ and $π$. The preliminary results are $y_{CP}=(1.11\pm0.22\pm0.11)%$ and $A_Γ=(-0.03\pm0.20\pm0.08)%$. We also report searches for CP violation in $D^0\rightarrow h^+h^-$ and $D^+\rightarrow K^0_S K^+$ decays. No evidence for CP violation in $D^0\rightarrow h^+h^-$ is observed with $A^{KK}_{…
The LHCb experiment recorded data corresponding to an integrated luminosity of 3.0 $fb^{-1}$ during its first run of data taking. These data yield the largest samples of charmed hadrons in the world and are used to search for CP violation in the $D^0$ system. Among the many measurements performed at LHCb, a measurement of the direct CP asymmetry in $D^0 \rightarrow K_S^0 K_S^0$ decays is presented and is found to be $A_{CP}(D^0 \rightarrow K_S^0 K_S^0) = (-2.9 \pm 5.2 \pm 2.2)\, \%, $ where the first uncertainty is statistical and the second systematic. This represents a significant improvemen…
The formulae for D^0-\bar{D}^0 or B^0-\bar{B}^0 mixing and CP violation at the τ-charm or B-meson factories are derived, for the case that only the decay-time distribution of one D or B meson is to be measured. In particular, we point out a new possibility to determine the D^0-\bar{D}^0 mixing rate in semileptonic D decays at the Ψ(4.14) resonance; and show that both direct and indirect CP asymmetries can be measured at the Υ(4S) resonance without ordering the decay times of two B_d mesons or measuring their difference.
We study UV complete theories where the Standard Model (SM) gauge group is extended with a new abelian $U(1)$, and the field content is augmented by an arbitrary number of scalar and fermion SM singlets, potentially including dark matter (DM) candidates. Considerations such as classical and quantum gauge invariance of the full theory and S-matrix unitarity, not applicable within a simplified model approach, are shown to have significant phenomenological consequences. The lack of gauge anomalies leads to compact relations among the $U(1)$ fermion charges, and puts a lower bound on the number of…
