Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userA novel observable for $C!P$ violation in multi-body decays and its application potential to charm and beauty meson decays
133
0
0.0
(
0
)
Authors
Zhen-Hua Zhang
Ask ChatGPT about the research
No Arabic abstract
A novel observable measuring the $C!P$ asymmetry in multi-body decays of heavy mesons, which is called the forward-backward asymmetry induced $C!P$ asymmetry (FBI-$C!P$A), $A_{CP}^{FB}$, is introduced. This observable has the dual advantages that 1) it can isolate the $C!P$ asymmetry associated with the interference of the $S$- and $P$-wave amplitude from that associated with the $S$- or $P$-wave amplitude alone; 2) it can effectively almost double the statistics comparing to the conventionally defined regional $C!P$ asymmetry. We also suggest to perform the measurements of FBI-$C!P$A in some three-body decay channels of charm and beauty mesons.
rate research
Read More
Since the discovery of CP violation more than 5 decades ago, this phenomenon is still attracting a lot of interest. Among the many fascinating aspects of this subject, this review is dedicated to direct CP violation in non-leptonic decays. The advances within the last decade have been enormous, driven by the increasingly large samples of b- and c-hadron decays, and have led to very interesting results such as large CP asymmetries in charmless B decays and the observation of direct CP violation in the charm sector. We address the quest for understanding the origin of strong phases, the importance of final state interactions and the relation with CPT symmetry, and different approaches to measure direct CP violation in these decays. The main experimental results and their implications are then discussed.
Precision tests of the Kobayashi-Maskawa model of CP violation are discussed, pointing out possible signatures for other sources of CP violation and for new flavor-changing operators. The current status of the most accurate tests is summarized.
A search for charge-parity ($C!P$) violation in $D^0 to K^- K^+$ and $D^0 to pi^- pi^+$ decays is reported, using $pp$ collision data corresponding to an integrated luminosity of 6 $mathrm{fb}^{-1}$ collected at a center-of-mass energy of 13 TeV with the LHCb detector. The flavor of the charm meson is inferred from the charge of the pion in $D^*(2010)^+ to D^0 pi^+$ decays or from the charge of the muon in $overline{B} to D^0 mu^-bar{ u}_mu X$ decays. The difference between the $C!P$ asymmetries in $D^0 to K^- K^+$ and $D^0 to pi^- pi^+$ decays is measured to be $Delta A_{C!P} = [ -18.2 pm 3.2,(rm stat.) pm 0.9,(rm syst.) ] times 10^{-4}$ for $pi$-tagged and $Delta A_{C!P} = [ -9 pm 8,(rm stat.) pm 5,(rm syst.) ] times 10^{-4} $ for $mu$-tagged $D^0$ mesons. Combining these with previous LHCb results leads to $$Delta A_{C!P} = ( -15.4 pm 2.9) times 10^{-4},$$ where the uncertainty includes both statistical and systematic contributions. The measured value differs from zero by more than five standard deviations. This is the first observation of $C!P$ violation in the decay of charm hadrons.
Beauty baryons are being observed in large numbers in the LHCb detector. The rich kinematic distributions of their multibody decays are therefore becoming accessible and provide us with new opportunities to search for CP violation. We analyse the angular distributions of some three- and four-body decays of spin-$1/2$ baryons using the Jacob-Wick helicity formalism. The asymmetries that provide access to small differences of CP-odd phases between decay amplitudes of identical CP-even phases are notably discussed. The understanding gained on processes featuring specific resonant intermediate states allows us to establish which asymmetries are relevant for what purpose. It is for instance shown that some CP-odd angular asymmetries measured by the LHCb collaboration in the $Lambda_b to Lambda,varphi to p,pi, K^+ K^-$ decay are expected to vanish identically.
Model-independent techniques for CP violation searches in multi-body charm decays are discussed. Examples of recent analyses from BaBar and LHCb are used to illustrate the experimental challenges involved.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
