Study CP Violation Research Articles

Customisation of the Large Area Picosecond Photodetector for the Upgrade II of the LHCb RICH

The LHCb is one of the four large experiments at CERN’s Large Hadron Collider (LHC). LHCb physics program includes studies of CP violation and decays of heavy-flavour hadrons. The RICH (Ring Imaging Cherenkov) detectors play a key role in particle identification. There is currently an intense detector R&D programme towards the LHCb Upgrade II, planned for 2032. One of the main photon detectors candidate for the Upgrade II of the RICH, the Large Area Picosecond Photodetector (LAPPD), will be presented, together with first tests and latest developments.

Pursue of CP violation in hyperon decay

In this paper, I review the status of CP violation in hyperon decay in light of recent progress by BESIII and the anticipated improvements at the super tau-charm facility. I emphasize the complementarity between kaons and hyperons for studying CP violation in [Formula: see text] processes.

A nearest-neighbor expansion of lepton flavor mixing in powers of the μ-τ permutation symmetry breaking effect

We point out that the observed pattern of lepton flavor mixing can be well described by a proper nearest-neighbor expansion of a constant 3×3 unitary matrix in powers of a small parameter characterizing the fine effect of μ-τ permutation symmetry breaking. We take an example of this kind for illustration, and provide complete discussions on the usefulness in the study of leptonic CP violation and unitarity triangles in matter.

CP Violation in the Quark Sector: Mixing Matrix Unitarity

Since its discovery in the 1960s, the violation of CP symmetry has intrigued scientists and stimulated the advancement of knowledge in particle physics. Numerous experiments were designed and built to study it in increasingly deeper detail. Nowadays, the phenomenon is well framed within the Standard Model of Particle Physics. Nevertheless, new results are being produced by modern experiments at colliders that challenge the current understanding of the model. In this article, the current status of CP violation studies and the role of CP violation in the search for effects beyond the Standard Model are described together with the prospects for ongoing and future experiments.

Modular flavor symmetric models

We review the modular flavor symmetric models of quarks and leptons focusing on our works. We present some flavor models of quarks and leptons by using finite modular groups and discuss the phenomenological implications. The modular flavor symmetry gives interesting phenomena at the fixed point of modulus. As a representative, we show the successful texture structure at the fixed point [Formula: see text]. We also study CP violation, which occurs through the modulus stabilization. Finally, we study SMEFT with modular flavor symmetry by including higher dimensional operators.

Estimated of CP violation in B^0 meson decays into D^{*+} and D^- mesons

The decay B^0rightarrow D^{*+}D^- is favorable mode for studying CP violation in the interference between mixing and decay for B^0 and bar{B}^0 mesons. The latest analysis of the CP parameters has been performed by the LHCb Collaboration values of S_{D^*D}=-,0.861pm 0.077pm 0.019, C_{D^*D}=-,0.059pm 0.092pm 0.020, triangle S_{D^*D}=0.019pm 0.075pm 0.012, triangle C_{D^*D}=-,0.031pm 0.092pm 0.016, and mathcal {A}_{D^*D}^{CP}=0.008pm 0.014pm 0.006pm 0.003. We have been estimated the parameters S_{D^*D} and C_{D^*D} of the B^0rightarrow D^{*+}D^- decay as -,0.709pm 0.024 and -,0.051pm 0.004. In the following, we have obtained the values of triangle S_{D^*D}=0.054pm 0.003 and triangle C_{D^*D}=0.020pm 0.001 and direct CP violation of 0.008pm 0.001. Also, we have calculated the branching ratio of B^0rightarrow D^{*+}D^- decay. The values obtained in this work are comparable with the corresponding experimental values.

Opportunities for new physics searches with heavy ions at colliders

Opportunities for searches for phenomena beyond the Standard Model (BSM) using heavy-ions beams at high energies are outlined. Different BSM searches proposed in the last years in collisions of heavy ions, mostly at the Large Hadron Collider, are summarized. A few concrete selected cases are reviewed including searches for axion-like particles, anomalous τ electromagnetic moments, magnetic monopoles, and dark photons. Expectations for the achievable sensitivities of these searches in the coming years are given. Studies of CP violation in hot and dense QCD matter and connections to ultrahigh-energy cosmic rays physics are also mentioned.

CP Violation in Baryon Decays at LHCb

Observations in astronomy suggest that our Universe contains an abundance of matter over antimatter, which can only be explained if the combined CP symmetry is violated. Studies of CP violation have driven the flavor physics with the aim of testing the Standard Model of particle physics and searching for physics beyond it. CP violation is discovered in strange, beauty, and charm meson systems; however, no conclusive sign of CP violation in baryon decays has been observed yet. This review summarizes CP violation studies performed by the LHCb experiment in charmless decays and rare decays of beauty baryons and singly Cabibbo-suppressed decays of charm baryons. A brief on prospects for future LHCb measurements is also discussed.

Measurement of the CP -even fraction of D0→π+π−π+π−

A measurement of the CP-even fraction of the decay D0→π+π−π+π− is performed with a quantum-correlated ψ(3770)→DD¯ data sample collected by the BESIII experiment, corresponding to an integrated luminosity of 2.93 fb−1. Using a combination of CP eigenstates, D→π+π−π0 and D→KS,L0π+π− as tagging modes, the CP-even fraction is measured to be F+4π=0.735±0.015±0.005, where the first uncertainty is statistical and the second is systematic. This is the most precise determination of this quantity to date. It provides valuable model-independent input for the measurement of the angle γ of the Cabibbo-Kobayashi-Maskawa matrix with B±→DK± decays, and for time-dependent studies of CP violation and mixing in the D0−D¯0 system.Received 22 August 2022Accepted 21 October 2022DOI:https://doi.org/10.1103/PhysRevD.106.092004Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasParticle mixing & oscillationsPropertiesCP violationParticles & Fields

BELLE AEROGEL CHERENKOV COUNTER – A DETECTOR FOR PARTICLE IDENTIFICATION

Particle identification, in particular the identification of charged pions and kaons, plays an important role for the studies of CP violation in B Factory experiments. For the BELLE detector at the KEK B-Factory in Japan, a threshold aerogel Cherenkov counter (ACC) has been used to separate pions and kaons in the momentum range between 1.0 GeV/c and 3.5 GeV/c. This paper gives a brief description of the ACC design, construction, monitoring system and its performance of the beam test and Monte-Carlo simulation.

New extraction of CP violation in b-baryon decays

We study CP violation in b-baryon decays of Ξb−→Ξ−D with D=D0,D¯0 and Di(i=1,2). We find that these baryonic decay processes provide an ideal opportunity to measure the weak phase due to the absence of the relative strong phase. Explicitly, we relate ρ¯ and η¯ the CKM elements with the decay rate ratios of Ri=Γ(Ξb−→Ξ−Di)/Γ(Ξb−→Ξ−D0) without the charge conjugate states. As a complementary, we also examine the decay distributions of Λb→Λ(→pπ−)D. There are in total 32 decay observables, which can be parameterized by 9 real parameters, allowing the experiments to extract the angle γ≡arg⁡(−VudVub⁎/VcdVcb⁎) in the CKM unitarity triangle. In addition, the feasibilities of the experimental measurements are discussed. We find that ρ¯ and η¯ can be extracted at LHCb Run3 from Ξb−→Ξ−D, and a full analysis of Λb→Λ(→pπ−)D is available at LHCb Run4.

Charmless b-hadron decays at LHCb

Measurements of CP asymmetries in charmless two-body B-meson decays can provide stringent tests of the Standard Model. In multibody decays, short and long-distance dynamics along with a sizeable effective weak phase in the interference between tree and penguin amplitudes can lead to a rich structure of CP violation as a function of the phase space. We present here the latest studies of CP violation in charmless b-hadron decays, in particular those with baryons in the initial and final states.

Recent CMS heavy flavor physics results

In this paper, recent results in the B-physics field achieved using proton–proton collision data at [Formula: see text] and [Formula: see text] TeV collected by CMS are presented. They include the angular analysis of the decay [Formula: see text] with Run 1 data, new measurements of D and B meson production cross-sections and CP violation studies using [Formula: see text] decays with Run 2 data. The results are compared with the Standard Model predictions. A measurement of the CP-violating phase [Formula: see text] achieved by combining results from both Run 1 and Run 2 data is also presented.

Lattice determination of I=0 and 2 ππ scattering phase shifts with a physical pion mass

Phase shifts for $s$-wave $\pi\pi$ scattering in both the $I=0$ and $I=2$ channels are determined from a lattice QCD calculation performed on 741 gauge configurations obeying G-parity boundary conditions with a physical pion mass and lattice size of $32^3\times 64$. These results support our recent study of direct CP violation in $K\to\pi\pi$ decay \cite{Abbott:2020hxn}, improving our earlier 2015 calculation \cite{Bai:2015nea}. The phase shifts are determined for both stationary and moving $\pi\pi$ systems, at three ($I=0$) and four ($I=2$) different total momenta. We implement several $\pi\pi$ interpolating operators including a scalar bilinear "$\sigma$" operator and paired single-pion bilinear operators with the constituent pions carrying various relative momenta. Several techniques, including correlated fitting and a bootstrap determination of p-values have been used to refine the results and a comparison with the generalized eigenvalue problem (GEVP) method is given. A detailed systematic error analysis is performed which allows phase shift results to be presented at a fixed energy.

Study of CP violation and CPT violation in K*(892)→KS,L0π decays at BESIII

The decays ${K}^{*}(892)\ensuremath{\rightarrow}{K}_{S,L}^{0}\ensuremath{\pi}$ can be used to study $CP$ violation and $CPT$ violation. The ${K}^{*}(892)$ (hereinafter referred to as ${K}^{*}$) meson can be produced via $J/\ensuremath{\psi}$ decays at BESIII. In this paper, we study $CP$ violation and ${K}_{S}^{0}\ensuremath{-}{K}_{L}^{0}$ asymmetry in the $J/\ensuremath{\psi}$ decays involving the ${K}^{*}$ meson in the final states and obtain the following results: ${\mathcal{A}}_{CP}(J/\ensuremath{\psi}\ensuremath{\rightarrow}{K}^{*}{f}_{J/\ensuremath{\psi}}\ensuremath{\rightarrow}{K}_{S}^{0}\ensuremath{\pi}{f}_{J/\ensuremath{\psi}})=(3.64\ifmmode\pm\else\textpm\fi{}0.04)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$, ${\mathcal{A}}_{CP}(J/\ensuremath{\psi}\ensuremath{\rightarrow}{K}^{*}{f}_{J/\ensuremath{\psi}}\ensuremath{\rightarrow}\phantom{\rule{0ex}{0ex}}{K}_{L}^{0}\ensuremath{\pi}{f}_{J/\ensuremath{\psi}})=(\ensuremath{-}3.32\ifmmode\pm\else\textpm\fi{}0.04)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$, and $R(J/\ensuremath{\psi}\ensuremath{\rightarrow}{K}^{*}{f}_{J/\ensuremath{\psi}}\ensuremath{\rightarrow}{K}_{S,L}^{0}\ensuremath{\pi}{f}_{J/\ensuremath{\psi}})=(3.51\ifmmode\pm\else\textpm\fi{}0.03)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$, $R(J/\ensuremath{\psi}\ensuremath{\rightarrow}{\overline{K}}^{*}{\overline{f}}_{J/\ensuremath{\psi}}\ensuremath{\rightarrow}{K}_{S,L}^{0}\ensuremath{\pi}{\overline{f}}_{J/\ensuremath{\psi}})=(\ensuremath{-}3.45\ifmmode\pm\else\textpm\fi{}0.03)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$. Based on two cases, the samples of ${10}^{10}$ and ${10}^{12}\text{ }\text{ }J/\ensuremath{\psi}$ events, we calculate the expected numbers of the observed signal events on the $CP$ violation and the ${K}_{S}^{0}\ensuremath{-}{K}_{L}^{0}$ asymmetry in the $J/\ensuremath{\psi}$ decays with ${K}^{*}$ meson in the final states, and we find that the BESIII experiment may be able to unambiguously observe $CP$ violation and ${K}_{S}^{0}\ensuremath{-}{K}_{L}^{0}$ asymmetry for each of these two cases. We study the possibility to constrain the $CPT$ violation parameter $z$ and discuss the sensitivity for the measurement of $z$ in $J/\ensuremath{\psi}$ decays with ${K}^{*}$ meson in the final states at BESIII. The sensitivity of the measurement of $z$ depends on the measured precision of the parameters ${m}_{L}\ensuremath{-}{m}_{S}$, ${\mathrm{\ensuremath{\Gamma}}}_{L}$, ${\mathrm{\ensuremath{\Gamma}}}_{S}$, $p$, and $q$ and the consistence between the values of ${t}_{0}$ and ${t}_{1}$ and the event selection criteria in experiment.

Probing CP violation in photon self-interactions with cavities

In this paper we study CP violation in photon self-interactions at low energy. These interactions, mediated by the effective operator FFFtilde{F} , where ( tilde{F} ) F is the (dual) electromagnetic field strength, have yet to be directly probed experimentally. Possible sources for such interactions are weakly coupled light scalars with both scalar and pseudoscalar couplings to photons (for instance, complex Higgs-portal scalars or the relaxion), or new light fermions coupled to photons via dipole operators. We propose a method to isolate the CP-violating contribution to the photon self-interactions using Superconducting Radio-Frequency cavities and vacuum birefringence experiments. In addition, we consider several theoretical and experimental indirect bounds on the scale of new physics associated with the above effective operator, and present projections for the sensitivity of the proposed experiments to this scale. We also discuss the implications of these bounds on the CP-violating couplings of new light particles coupled to photons.

Electric dipole moment constraints on CP-violating heavy-quark Yukawas at next-to-leading order

Electric dipole moments are sensitive probes of new phases in the Higgs Yukawa couplings. We calculate the complete two-loop QCD anomalous dimension matrix for the mixing of CP-odd scalar and tensor operators and apply our results for a phenomenological study of CP violation in the bottom and charm Yukawa couplings. We find large shifts of the induced Wilson coefficients at next-to-leading-logarithmic order. Using the experimental bound on the electric dipole moments of the neutron and mercury, we update the constraints on CP-violating phases in the bottom and charm quark Yukawas.

Feasibility study of CP violation in decays at the Super Tau Charm Facility * *Supported by the Double First-Class university project foundation of USTC, USTC Research Funds of the Double First-Class Initiative YD2030002005 and the National Natural Science Foundation of China (11625523). The author XWK is supported by the National Natural Science Foundation of China (11805012) and the Fundamental Research

We report a feasibility study for violation in decays at a Super Tau Charm Facility (STCF). With an expected luminosity of 1 ab collected by STCF per year at a center-of-mass energy of 4.26 GeV, the statistical sensitivity for CP violation is determined to be of order by measuring the decay-rate difference between and . The analysis is performed using a reliable fast simulation software package, which can describe the detector responses properly and vary the responses flexibly for further optimization. Moreover, the energy-dependent efficiencies for reconstructing are presented. The expected CP sensitivity is proportional to in the energy region from 4.0 to 5.0 GeV. The sensitivity of CP violation is of order with 10 ab integrated luminosity, which is equivalent to ten years' data taking in this energy region at STCF.

The history of LHCb

In this paper, we describe the history of the LHCb experiment over the last three decades, and its remarkable successes and achievements. LHCb was conceived primarily as a {b} -physics experiment, dedicated to CP violation studies and measurements of very rare {{b}} decays; however, the tremendous potential for {c} -physics was also clear. At first data taking, the versatility of the experiment as a general-purpose detector in the forward region also became evident, with measurements achievable such as electroweak physics, jets and new particle searches in open states. These were facilitated by the excellent capability of the detector to identify muons and to reconstruct decay vertices close to the primary {{p}} {{p}} interaction region. By the end of the LHC Run 2 in 2018, before the accelerator paused for its second long shut down, LHCb had measured the CKM quark mixing matrix elements and CP violation parameters to world-leading precision in the heavy-quark systems. The experiment had also measured many rare decays of {b} and {c} quark mesons and baryons to below their Standard Model expectations, some down to branching ratios of order 10^{-9}. In addition, world knowledge of {{b}} and {{c}} spectroscopy had improved significantly through discoveries of many new resonances already anticipated in the quark model, and also adding new exotic four and five quark states. The paper describes the evolution of the LHCb detector, from conception to its operation at the present time. The authors’ subjective summary of the experiment’s important contributions is then presented, demonstrating the wide domain of successful physics measurements that have been achieved over the years.

CP violation in B decays

L’étude expérimentale de la brisure de la symétrie CP dans les désintégrations de mésons beaux (B) a apporté des contributions majeures à notre compréhension de la nature : (i) Elle a établi que le mécanisme de Kobayashi-Maskawa est la source dominante de brisure de la symétrie CP dans les systèmes des mésons K et B. (ii) Elle a amélioré significativement la précision des paramètres qui décrivent la matrice de mélange des quarks Cabibbo–Kobayashi–Maskawa. (iii) Elle a prouvé que l’échelle d’énergie d’une nouvelle physique avec des couplages de changement de saveurs d’ordre unité, devait être supérieure à 𝒪(10 3 TeV). Des progrès sont attendus, dans cette décennie et la suivante, des expériences du LHC et Belle II. L’état de l’art de cette Physique et les perspectives des expériences futures sont discutés dans cet article.