We discusses the charge asymmetry in $ B\rightarrow D\bar DK$ decays with an invariant mass of the $D\bar D$ pair near the $Ψ(3770)$ resonance. Unlike $ Ψ(3770) $ decays in $ e^+e^- $ annihilation, in $B^+$ decays the probability of $D^0\bar D^0$ production is almost three times higher than $D^+ D^-$. In $B^0$ decays, the ratio of these probabilities will be opposite. The effect is explained by the fact that, in $B$ -meson decays, the $D\bar D$ pair is produced in a superposition of isoscalar and isovector states, and only in combination with $K$ -mesons the total state has $ 1/2 $ isospin. We present a simple model in which the interference of the nonresonant isovector amplitude with the resonant isoscalar amplitude explains the experimental data.
$CP$ violation of the decay $B^{\pm}\rightarrow π^{\pm}π^{+}π^{-}$ in the $f_{0}(500)-ρ(770)^{0}$ interfering region is analyzed. The forward-backward asymmetries (FBAs) and the corresponding $CP$ asymmetries FB-$CP$As are particularly investigated. To isolate the $CP$V caused by the interference of different partial wave more cleanly, we also introduce the direct-$CP$V-subtracted FB-$CP$A. Based on the LHCb data, we extract the FBAs, FB-$CP$As, direct-$CP$V-subtracted FB-$CP$A, as well as the regional $CP$As with invariant mass of the $π^{+}π^{-}$ pair in the range 0.2 GeV/$c^{2}<\sqrt{s_{\te…
The forward-backward asymmetry induced $CP$ asymmetry in ${\overline{B}}^{0}\rightarrow K^{-}π^{+}π^{0}$ in phase space around the resonances ${\overline{K}}^{*}(892)^{0}$ and ${\overline{K}}^{*}_{0}(700)$
University of South China（南华大学）；Zhejiang Wanli University（浙江万里学院）
We report on the extrapolated measurements related to the flavour-changing-neutral-current(FCNC) $b\rightarrow s$ and $b\rightarrow d$ transitions with the Belle II data. The branching fraction(BF) and raw asymmetry measurements of the exclusive decay $\bar{B}\rightarrow X_{q}γ$, time-dependent $CP$ asymmetry in the transition $b\rightarrow sγ$, angular analysis of $B\rightarrow K^*ll$ and $B\rightarrow X_sll$ are discussed. We also report on the searches for the decay $B\rightarrow hνν$. Most of these analyses are extrapolated with 5 and 50 ab$^{-1}$ Belle II data.
In the framework of Perturbative QCD (PQCD) approach we study the direct $CP$ asymmetry for the decay channel $\bar{B}_{s}\rightarrow Pπ^+π^-$ around the resonance range via the $ρ-ω$ mixing mechanism (where P refer to pseudoscalar meson). We find that the $CP$ asymmetry can be enhanced by $ρ-ω$ mixing when the masses of the $π^+π^-$ pairs are at the area of $ρ-ω$ resonance, and the maximum $CP$ asymmetry can reach 59{\%} for the relevant decay channels.
An investigation about localized CP asymmetries for the processes of $\bar{B}_{s}^{0} \rightarrow π^{+}π^{-}π^{0} (K^{0})$ is presented in this paper. The innovation of this paper is that there is a consideration of three-particle $ρ^0(770)$, $ω(782)$ and $ϕ(1020)$ interferences effect. Generally, $ω(782)$ and $ϕ(1020)$ both can decay into $π^+π^-$ pair where can cause extremely small contribution from isospin symmetry breaking. Nevertheless, our analysis shows that $\bar{B}_{s}^{0} \rightarrow π^+π^-π^{0}(K^{0})$ decay process can bring differential CP asymmetry about $65\%$ ($36\%$) because …
We present estimates of transverse single spin asymmetry (TSSA) in $p+p^\uparrow \rightarrow J/ψ+X$ within the colour evaporation model of charmonium production in a generalized parton model (GPM) framework, using the recently obtained best fit parameters for the gluon Sivers function (GSF) extracted from PHENIX data on TSSA in $p+p^\uparrow \to π^0+X$ at midrapidity. We calculate asymmetry at $\sqrt{s} = 200$ GeV, and compare the results with PHENIX data on TSSA in the process $p + p^\uparrow \to J/ψ+X$. We also present estimates for asymmetry at $\sqrt{s} = 115 $ GeV corresponding to the pro…
In this article, we investigate the $\cos2ϕ_t$ azimuthal asymmetry in $e ~p\rightarrow e ~J/ψ~Jet~ X$, where the $J/ψ$-jet pair is almost back-to-back in the transverse plane, within the framework of the generalized parton model(GPM). We use non-relativistic QCD(NRQCD) to calculate the $J/ψ$ production amplitude and incorporate both color singlet(CS) and color octet(CO) contributions to the asymmetry. We estimate the asymmetry using different parameterizations of the gluon TMDs in the kinematics that can be accessed at the future electron-ion collider (EIC) and also investigate the impact of t…
Decays $K^{+} \rightarrow μ^{+}ν_μ ν\bar ν$ and $K^{+}\rightarrow e^{+}ν_{e} ν\bar ν$ are examined to the leading order in momenta in the framework of Chiral Perturbation Theory. Predictions of the Standard Model for the muon and electron differential energy spectra and branching ratios of $K_{μ3 ν}$ and $K_{e 3 ν}$ are presented.
In this paper, we study the Cabibbo favored three body non-leptonic D^+ \rightarrow K^- π^+ π^+ decay. We show that the corresponding direct CP asymmetry is so tiny in the framework of the Standard Model and is out of the experimental range. Motivated by this result we extend the study of the CP asymmetry to include a toy model with CP violating weak phase equals 20 degrees in a_2, a model with extra gauge bosons within Left-Right Grand Unification models and a model with charged Higgs boson. We show that the toy model can strongly improve the SM prediction of the CP asymmetry to be about 30%.…
The rare inclusive decay $\bar{B}\rightarrow X_sγ$ is an important probe of physics beyond the standard model. The largest uncertainty on the decay rate and CP asymmetry comes from operators that appear at order $1/m_b$ in the heavy quark expansion. One of the three leading contributions in the heavy quark expansion, $Q_1^q-Q_{7γ}$ is described by a non-local function whose moments are related to HQET parameters. We use recent progress in our knowledge of these parameters to better constrain their contributions to the total rate and CP asymmetry.
Through $B\bar{B}$ mixing system, one can construct an asymmetry which naively seems to be a time reversal (T) odd quantity. In this article, the two processes $(\mathrm{a})\: B_-\rightarrow \bar{B^0}$ and $(\mathrm{b})\: \bar{B^0}\rightarrow B_-$ are used to construct the event number asymmetry. The CP violation of Kaon system denoted as $ε_K$ contributes to observables and we evaluate the contribution from $ε_K$ explicitly. The asymmetry is formulated with phase convention independent parameters which are invariant under redefinition of phase of quark fields. The overall factors of the time …
We compute the contribution of the decays $K_L \rightarrow π^0 Q \bar Q$ and $K^+ \rightarrow π^+ Q \bar Q$, where $Q$ is a dark fermion of the dark sector, to the measured widths for the rare decays $K^+\rightarrow π^+ ν\bar ν$ and $K_L\rightarrow π^0 ν\bar ν$. The recent experimental limit for $Γ(K^+ \rightarrow π^+ ν\bar ν)$ from NA62 sets a new and very strict bound on the dark-sector parameters. A branching ratio for $K_L \rightarrow π^0 Q \bar Q$ within the reach of the KOTO sensitivity is possible. The Grossman-Nir bound is weakened by the asymmetric effect of the different kinematic cu…
We perform a helicity amplitude analysis for the processes of $e^+e^-$$\rightarrow$$J/ψ,ψ(2S)\rightarrowΞ(1530)\barΞ(1530)\rightarrowππΞ\barΞ\rightarrowΛ\bar\Lambda4π\rightarrow p\bar{p}6π$. The joint angular distribution for these processes are obtained, which allows a proper estimation of the detection efficiency using helicity amplitude information. In addition, the sensitivities of measurement of hyperon asymmetry decay parameters for these processes are discussed.
Recent experimental results from the LHCb, BaBar and Belle collaborations on the semitauonic decays of $B$ meson, $\bar{B}\rightarrow D^{(\ast)}τ\barν$, showing a significant deviation from the Standard Model (SM), hint towards a new physics scenario beyond the SM. In this work, we show that these enhanced decay rates can be explained within the framework of $E_{6}$ motivated Alternative Left-Right Symmetric Model (ALRSM), which has been successful in explaining the recent CMS excesses and has the feature of accommodating high scale leptogenesis. The R-parity conserving couplings in ALRSM can …
In this paper a general method to measure the longitudinal polarization of $τ$ lepton in the process $pp \rightarrow Z^{0} \rightarrow ττ$ is described. The method of optimal observable allows to distinguish between the $τ$ lepton helicity states with maximum possible sensitivity. The optimal observable for the main $τ$ decay modes ($e/μνν$, $πν$, $ρν$, $a_{1}ν$) that can be identified by CMS or ATLAS detectors is described. The analyzing power for $τ$ polarization can be further gained by taking into account a correlation between longitudinal spin states of $τ^{+}$ and $τ^{-}$. The theoretica…
We review $CP$-violating observables in flavor tagged and untagged $D^0 \rightarrow K^{-}π^{+}$ decays and evaluate the $CP$ asymmetry difference between the two decays. We note that this commonly neglected difference is not zero in principle and can be significant in future $B$ factory experiments. We also construct an expression to extract the strong phase difference between $\bar{D}^0 \rightarrow K^-π^+$ and $D^0 \rightarrow K^-π^+$ decays, independently of existing experimental methods.
This paper presents perturbative QCD predictions of the electron charge asymmetry for the inclusive $W^{\pm}+X \rightarrow e^{\pm} ν+X$ production in proton-proton (pp) collisions. Perturbative QCD calculations are performed at next-to-next-to-leading order (NNLO) accuracy by using different parton distribution function (PDF) models at 8 TeV, 13 TeV, and 14 TeV center-of-mass energies of the CERN LHC pp collisions. The NNLO calculations are performed for the electrons to have transverse momentum more than 20 GeV in the forward electron pseudorapidity region $2.0 \leq η_{e} \leq 4.25$. The NNLO…
We show that the final-state interaction perfectly explains the recent experimental data of BESIII Collaboration on the near-threshold invariant-mass spectrum of $Λ\barΛ$ in the process $e^+e^-\rightarrowϕΛ\barΛ$. The position of peak in invariant-mass spectrum is above the threshold though the interaction of $Λ$ and $\barΛ$ is due to an attractive potential. This potential has a simple form and depends only on two parameters. We show that the invariant-mass spectrum is consistent with the quantum numbers $J^{PC}=1^{++}$ and $2^{++}$ of $Λ\barΛ$ pair but contradicts to $J^{PC}=2^{-+}$.
We propose a strategy for new physics searches in channels which contain a boosted $Z$ boson in the final state. Our proposal exploits the previously overlooked advantages of boosted $Z\rightarrow ν\barν$ topologies, where collimated neutrinos result in signals with large missing energy. We illustrate the advantage of this channel in a case study of singly produced TeV scale charge 2/3 fermionic top partners ($T'$) which decay to $t+Z$. A comparison with the di-leptonic channel reveals that signals with missing energy offer superior probes of new physics at TeV scales, despite the large $t\bar…
At Moriond 2019, Belle collaboration has announced new measurements on the flavour ratios $R_D - R_{D^*}$ which are consistent with their Standard Model predictions within $1.2σ$. After inclusion of these measurements, the global tension in $R_D - R_{D^*}$ has reduced from $4.1σ$ to $3.1σ$ which is still significant. The measurements of these ratios indicate towards the violation of lepton flavor universality in $b\rightarrow c\,l\,\barν$ decay. Assuming new physics in $b\rightarrow c\,τ\,\barν$ transition, we have done a global fit to all available data in this sector to identify the allowed …
We point out that the CP asymmetries in the decays $D^0\rightarrow K_{S} K^{*0}$ and $D^0\rightarrow K_{S} \overline{K}{}^{*0}$ are potential discovery channels for charm CP violation in the Standard Model. We stress that no flavor tagging is necessary, the untagged CP asymmetry $a_{CP}^{\mathrm{dir}}(D \to K_S K^{*0})$ is essentially equal to the tagged one, so that the untagged measurement comes with a significant statistical gain. Depending on the relevant strong phase, $\vert a_{CP}^{\text{dir, untag}}\vert$ can be as large as $0.003$. The CP asymmetry is dominantly generated by exchange d…
It is widely known that the $ZH$ production channel provides a promising probe to the $H \rightarrow b\bar{b}$ decay at the LHC, when the Higgs and the $Z$ bosons are highly boosted along the transverse direction. We show how information on the $Z$ boson polarization -- that is disregarded in the current LHC analyses -- can relevantly improve the signal from background discrimination, helping us to observe and achieve a larger precision for the $H \rightarrow b\bar{b}$ measurement in the $Z(\ell\ell)H$ channel.
We present a new approach to jet definition alternative to clustering methods, such as the anti-$k_T$ scheme, that exploit kinematic data directly. Instead the new method uses kinematic information to represent the particles in a multidimensional space, as in spectral clustering. After confirming its Infra-Red (IR) safety, we compare its performance in analysing $gg \rightarrow H_{125~\rm GeV} \rightarrow H_{40~\rm GeV}H_{40~\rm GeV} \rightarrow b\bar{b}b\bar{b}$, $gg \rightarrow H_{500~\rm GeV} \rightarrow H_{125~\rm GeV}H_{125~\rm GeV} \rightarrow b\bar{b}b\bar{b}$ and $gg, q\bar{q} \rightar…
The rare pion decays $π^+{\rightarrow}μ^+ν_μν\barν$ and $π^+{\rightarrow}e^+ν_{e}ν\barν$ are allowed in the Standard Model but highly suppressed. These decays were searched for using data from the PIENU experiment. A first result for $Γ(π^+{\rightarrow}μ^+ν_μν\barν)/Γ(π^+{\rightarrow}μ^+ν_μ)<8.6{\times}10^{-6}$, and an improved measurement $Γ(π^+{\rightarrow}{e}^+ν_{e}ν\barν)/Γ(π^+{\rightarrow}μ^+ν_μ)<1.6{\times}10^{-7}$ were obtained.
This contribution outlines the implementation of the matrix element method (MEM) in the search for $\text{t}\bar{\text{t}}$H, H $\rightarrow \text{b}\bar{\text{b}}$ events. In particular, the evaluation of the transfer functions, which relate detector level to parton level quantities in the computation of the MEM, is described. In addition, it is presented how jet substructure reconstruction can be combined with the MEM. The combination of these techniques leads to a decrease in computation time by up to 90% and an increase in event selection efficiency of 30% in the high Higgs boson and top q…
In this paper we investigate CP violation in charged decays of $D$ meson. Particularly, we study the direct CP asymmetry of the Cabibbo favored non-leptonic $D^+ \rightarrow \bar K^0 π^+$ and the doubly Cabibbo-suppressed decay mode $D^+ \rightarrow K^0 π^+$ within standard model, two Higgs doublet model with generic Yukawa structure and left right symmetric models. In the standard model, we first derive the contributions from box and di-penguin diagrams contributing to their amplitudes which are relevant to the generation of the weak phases essential for non-vanishing direct CP violation. The…
The decays $K^{\ast}(892)\rightarrow K_{S,L}^{0}π$ can be used to study CP violation and CPT violation. The $K^{\ast}(892)$ (hereinafter referred to as $K^{\ast}$) meson can be produced via $J/ψ$ decays at BESIII. In this paper, we study CP violation and $K_S^0-K_L^0$ asymmetry in the $J/ψ$ decays involving the $K^{\ast}$ meson in the final states and obtain the following results \begin{align} {\mathcal A}_{CP}\left(J/ψ\rightarrow K^{\ast}f_{J/ψ}\rightarrow K^0_{S}πf_{J/ψ}\right)=\left(3.64\pm0.04\right)\times 10^{-3},\nonumber\\ {\mathcal A}_{CP}\left(J/ψ\rightarrow K^{\ast}f_{J/ψ}\rightarrow…
The most precise measurement of the $CP$ asymmetry in the decay $B^-\rightarrow D_s^-D^0$ has been reported by LHCb collaboration with the value of $(-0.4\pm0.5\pm0.5)\%$. In this study, the $CP$ violation in the decay $B^-\rightarrow D_s^-D^0$ has been calculated under the factorization approach. This decay mode includes current-current tree and penguin diagrams and their amplitudes are considered separately. In each of the tree and penguin amplitudes, the strong and weak phases have been introduced. The $CP$ asymmetry has been calculated in this work to be $(-0.35\pm0.03)\%$. Finally, from t…
We investigate $ B_s^0\rightarrow l^+ l^-γ$ decays in a nonuniversal Z' model derived from extension of the standard model (SM). Considering the Z'-mediated flavor changing neutral current (FCNC) effects we calculate the branching ratio and forwardbackward asymmetry for $ B_s^0\rightarrow l^+ l^-γ$ decay processes. We compare the obtained results with predictions of the SM and discuss the sensitivity of the observables to Z' boson coupling parameters. We find the branching ratios are enhanced by one order from SM predictions in Z' model scenario. We also observe the variation of forward-backwa…
Babar collaboration has reported an intriguing opposite sign in the integrated decay rate asymmetry $A_{cp}(τ\rightarrow K_{S}πν_τ)$ than that of SM prediction from the known K0 - $\bar{K0}$ mixing. Babar's result deviate from the SM prediction by about 2.7$σ$. If the result stands with higher precision in the future experiments, the observed sign anomaly in the $A_{cp}(τ\rightarrow K_{S}πν_τ)$ can most likely come only from some new physics occurring possibly in both hadronic as well as leptonic sectors. In this work, we will give an improved analysis of our previous work where we have illust…
We calculate the zeroes of angular observables $P_4^{'}$ and $P_5^{'}$ of 4 - body angular distribution of $B\rightarrow K^{*} (\rightarrow K π) l^+ l^-$ where LHCb, in its analysis of form factor independent angular observables, has found deviations from standard model predictions in one of the $q^2$ bins. In the large recoil region, we obtain relations between the zeroes of $P_4^{'}$, $P_5^{'}$ and the zero of forward-backward asymmetry of lepton pair. These relations, in the considered region, are independent of hadronic uncertainties and depend only on Wilson coefficients. We also construc…
The cross sections of $e^+e^- \rightarrow πZ_c(3900) \rightarrow ππJ/ψ$ and $e^+e^- \rightarrow πZ_c(3900) \rightarrow πD\bar{D}^{*}$ have been measured by BESIII experiment. We try to perform a combined fit to the cross sections with one Breit-Wigner function, the fit results show the structure's mass and width are $M=(4232\pm5)$ MeV/$c^2$, $Γ=(65\pm21)$ MeV. The ratio $\frac{\mathcal{B}(Z_c(3900)\rightarrow D\bar{D}^{*})}{\mathcal{B}(Z_c(3900)\rightarrowπJ/ψ)}$ is determined to be $(16\pm6)$. We also try to fit the cross sections with two Breit-Wigner functions, while we can't come to any de…
Within the quasi-two-body decay model, we study the localized $CP$ violation and branching fraction of the four-body decay $\bar{B}^0\rightarrow [K^-π^+]_{S/V}[π^+π^-]_{V/S} \rightarrow K^-π^+π^-π^+$ when $K^-π^+$ and $π^-π^+$ pair invariant masses are $0.35<m_{K^-π^+}<2.04 \, \mathrm{GeV}$ and $0<m_{π^-π^+}<1.06\, \mathrm{GeV}$, with the pairs being dominated by the $\bar{K}^*_0(700)^0$, $\bar{K}^*(892)^0$, $\bar{K}^*(1410)^0$, $\bar{K}^*_0(1430)$ and $\bar{K}^*(1680)^0$, and $f_0(500)$, $ρ^0(770)$ , $ω(782)$ and $f_0(980)$ resonances, respectively. When dealing with the dynamical functions o…
