GPU-based optical photon simulation for the LHCb RICH 1 Detector

We present the investigation of the use of Opticks, a GPU-accelerated optical photon interface with the LHCb detector simulation, to improve computation time of optical photon propagation. The hybrid workflow, combining the particle simulation package Geant4 and Opticks, offloads optical photon propagation to GPUs, thereby accelerating the overall simulation process. The consistency of the results obtained from Geant4 and Opticks simulations is verified with a simplified LHCb RICH 1 detector geometry, demonstrating the feasibility of the proposed approach. In addition, the ongoing transition to the NVIDIA OptiX 7 API and re-structuring of Opticks code is discussed within the context of HEP simulation workflows, with caveats explored

Overview of the CP violation and mixing in the charm sector

An overview of the most recent experimental measurements in charm CP violation and mixing parameters is presented here

Mixing and indirect CPV in multibody charm decays at LHCb

The latest results in mixing and indirect CP violation in charm decays at LHCb are presented. The mixing in charm is observed in D->K3pi decays for a first time, and the non-mixing hypothesis is rejected with a significance of 8.2 standard deviations. The analysis of these decays at LHCb provides important constraints for the strong phase and the coherence factor needed as an external input in the determination of the CKM angle gamma. The decay mode D->Kshh is the golden mode for measuring the charm mixing parameters. The results based on 1 fb-1 collected during 2011 are shown.</p

CP violation searches in the charm sector at LHCb

LHCb has collected the world's largest sample of charmed hadrons, thus enabling measurements of direct and indirect CP violation parameters of D^0 mesons to be made with unprecedented precision. The difference in CP asymmetries between the singly Cabibbo-suppressed (SCS) D^0 -> K+K- and D^0 -> pi+pi- decays (Delta A_CP) has emerged as a powerful observable to search for direct CPV in the charm sector. By taking the difference between the two modes, most of the asymmetries induced by the detector or coming from the production mechanism are cancelled. The measurement of Delta A_CP done at LHCb is the most precise measurement of a time-integrated CP asymmetry in the charm sector from a single experiment, with a precision reaching the sub-permille level. Two independent measurements of Delta A_CP based on complementary data sets will be presented. Related 2-body searches and searches for direct CP violation in multi-body decays of the D^0 mesons will be discussed. Indirect CP violation in charm is measured through the observable A_Gamma, defined as the time-dependent asymmetry in the decay rates of the SCS D^0 -> h+h- decays. Two independent measurements carried out at LHCb, based on two complementary data sets, will also be presented. Finally, prospects for CP violation searches with Run 2 data and beyond will be discussed

CPCP vioaltion searches in the charm sector at LHCb

LHCb has collected the world's largest sample of charmed hadrons, thus enabling measurements of direct and indirect CP violation parameters of D^0 mesons to be made with unprecedented precision. The difference in CP asymmetries between the singly Cabibbo-suppressed (SCS) D^0 -> K+K- and D^0 -> pi+pi- decays (Delta A_CP) has emerged as a powerful observable to search for direct CPV in the charm sector. By taking the difference between the two modes, most of the asymmetries induced by the detector or coming from the production mechanism are cancelled. The measurement of Delta A_CP done at LHCb is the most precise measurement of a time-integrated CP asymmetry in the charm sector from a single experiment, with a precision reaching the sub-permille level. Two independent measurements of Delta A_CP based on complementary data sets will be presented. Related 2-body searches and searches for direct CP violation in multi-body decays of the D^0 mesons will be discussed. Indirect CP violation in charm is measured through the observable A_Gamma, defined as the time-dependent asymmetry in the decay rates of the SCS D^0 -> h+h- decays. Two independent measurements carried out at LHCb, based on two complementary data sets, will also be presented. Finally, prospects for CP violation searches with Run 2 data and beyond will be discussed

Charm mixing and CP violation at LHCb

LHCb has collected the world's largest sample of charmed hadrons. This sample is used to search for direct CP violation in the multibody prompt charm decays $D^0 -> \pi^-\pi^+\pi^0$. The search is employing an unbinned model independent method known as the energy test. Using the data collected by LHCb at centre-of-mass energy of 8 TeV, the world's best sensitivity to CP violation in this decay is achieved. The data are found to be consistent with the hypothesis of CP symmetry with a p-value of $(2.6 \pm 0.5)\%$. New measurements of indirect CP violation in muon tagged $D^0$ decays to two-body CP even final states are presented. The time dependent CP asymmetries in the decay rates of the singly Cabibbo-suppressed decays $D^0->KK$ and $D^0->\pi\pi$ decays using the full LHCb run 1 data set are determined to be $A_{\Gamma} (K^-K^+) = (-0.134 \pm 0.077 ^{+0.026}_{-0.034})\% ; A_{\Gamma} (\pi^-\pi^+) = (-0.092 \pm 0.145 ^{+0.025}_{-0.033})\%$, and are compatible with the hypothesis of no indirect CPV and with previous LHCb measurements