One of the outstanding problems in physics is to explain the baryon-anti-baryon asymmetry observed in nature. According to the well-known Sakharov criterion for explaining the observed asymmetry, it is essential that $CP$ violation exist. Even though $CP$ violation has been observed in meson decays and is an integral part of the standard model (SM), measurements in meson decays indicate that $CP$ violation in the SM is insufficient to explain the observed baryon-anti-baryon asymmetry. SM predicts the existence of yet to be observed $CP$ violation in baryon decays. A critical test of the SM requires that $CP$ violation be measured in baryon decays as well, in order to verify that it agrees with the measurement using meson decays. In this letter we propose a new method to measure $CP$ violating phase in $b$-baryons, using interference arising implicitly due to Bose symmetry considerations of the decaying amplitudes.
Several baryons containing a heavy b-quark, the b-baryons, have been discovered. The charmless two-body decays of b-baryons can provide a new platform for CP violating studies in a similar way as charmless two-body decays of B-meson. In b-baryon decays there are new CP violating observable related to baryon polarization. We show that in the flavor $SU(3)$ limit there exist relations involve different combinations of the decay amplitudes compared with those in CP violating rate asymmetry. These new relations therefore provide interesting tests for the mechanism of CP in the standard model (SM) …
LHCb is a dedicated heavy flavour physics precision experiment at the LHC searching for New Physics (NP) beyond the Standard Model (SM) through the study of very rare decays of beauty and charm-flavoured hadrons and precision measurements of CP-violating observables. In this review I will present a selection of recent precision measurements of CP-violating observables in the decays of beauty and charm-flavoured hadrons. These measurements are based on an integrated luminosity of up to $1.0 \rm{fb}^{-1}$ collected by LHCb in 2011.
After the present establishment of CP-Violation in $B_{d}$-physics, consistency tests of unitarity in the Standard Model and the search of new phenomena are compulsory. I illustrate the way to look for T-violation, without contamination of absorptive parts, in correlated decays in B-factories. $B_{s}$-mixing and penguin-mediated $B_{s}$-decays are of prime importance in hadronic machines to look for new physics.
We fit the ${\cal CKM}$-matrix to all recent data with the following free parameters: three mixing angles, the CP-violating angle $δ$ in the Maiani parametrisation, the top quark mass $m_t$, and the product $f_B{\cal B}_{\B}^{1/2}$, where $f_B$ is the $B$-meson decay parameter and ${\cal B}_{\B}$ is the bag parameter. Our fits span a contiguous region in the $(f_B{\cal B}_{\B}^{1/2},\ \cosδ)$--plane, limited by $0.117\lsim f_B{\cal B}_{\B}^{1/2}/{\rm GeV}\lsim 0.231$ and --0.95 $\lsim$ $\cosδ$ $\lsim$ 0.70. The parameters $f_B{\cal B}_{\B}^{1/2}$ and $\cosδ$ are strongly positively correlated.
Several baryons containing a heavy b-quark have been discovered. The decays of these states provide new platform for testing the standard model (SM). We study $CP$ violation in SM for charmless two-body decays of the flavor $SU(3)$ anti-triplet beauty baryon (b-baryon) ${\cal B} = (Ξ^-_b,\;Ξ^0_b,\;Λ_b^0)$ in a model independent way. We found, in the flavor $SU(3)$ symmetry limit, a set of new predictive relations among the branching ratio $Br$ and $CP$ asymmetry $A_{CP}$ for $\cal B$ decays, such as $A_{CP}(Ξ_b^-\to K^0 Ξ^-)/A_{CP}(Ξ_b^-\to \bar K^0 Σ^-) = - Br(Ξ_b^- \to \bar K^0 Σ^-)/Br(Ξ_b^-…
We address the possibility that CP-violation in $B_s-\bar B_s$ mixing may help explain the origin of the cosmic baryon asymmetry. We propose a new baryogenesis mechanism - "Electroweak Beautygenesis" - explicitly showing that these two CP-violating phenomena can be sourced by a common CP-phase. As an illustration, we work in the Two-Higgs-Doublet model. Because the relevant CP-phase is flavor off-diagonal, this mechanism is less severely constrained by null results of electric dipole moment searches than other scenarios. We show how measurements of flavor observables by the D0, CDF, and LHCb c…
As the hint for CP violating new physics in B-> phi Ks has weakened, we reconsider the possibility of near maximal mixing between \tilde s_R-\tilde b_R squarks. Such a right-handed strange-beauty squark \widetilde{sb}_{1} can be realized by combining supersymmetry with an approximate Abelian flavor symmetry, and comes with a unique new CP violating phase from right-handed quark mixing. Naturally heavy strange-beauty squark and gluino, of order 0.5 to 1 TeV, are easily accommodated by recent time-dependent CP violation measurements in Bd -> phi K^0 and pi^0 K^0. Because of near maximal mixing, …
Planar L-loop maximally helicity violating amplitudes in N = 4 supersymmetric Yang-Mills theory are believed to possess the remarkable property of satisfying iteration relations in L. We propose a simple new method for studying the iteration relations for four-particle amplitudes which involves the use of certain linear differential operators and eliminates the need to fully evaluate any loop integrals. We carry out this procedure in explicit detail for the two-loop amplitude and argue that this method can be used to prove the iteration relations to all loops up to polynomials in logarithms.
In a bent crystal the $P$-odd effect of short-lived baryon spin rotation could imitate spin rotation caused by assumed EDM. Use of different behavior of $P$-odd and $T$-odd spin rotations at crystal turning around the direction of particle momentum makes it possible to exclude $P$-odd rotation contribution, when measuring short-lived baryons EDM. Subtraction of the measurement results for angle ranges $φ$ and $φ+ π$ from each other enables measuring $T$-odd rotation at scattering of negatively charged beauty and neutral baryons by axes of unbent crystal.
The $R$-parity-violating Minimal Supersymmetric Standard Model (RPV-MSSM) can naturally accommodate massive neutrinos as required by the oscillation data. However, studying the phenomenology is complicated due to the large number of undetermined parameters involved. Thus, studies are usually restricted to specific submodels. In this work, we develop an approach that allows us to be less restrictive. Working in (almost) the completely general RPV-MSSM setting, we analyze the structure of the neutrino mass matrix, and identify -- for the case of two massive neutrinos -- only four minimal classes…
We study the two scalar leptoquarks capable of generating chirally-enhanced, sign-dependent contributions to lepton magnetic dipole moments (MDMs) and electric dipole moments (EDMs), $R_2\sim (\mathbf{3}, \mathbf{2}, 7/6)$ and $S_1\sim (\mathbf{3}, \mathbf{1}, -1/3)$. We consider the case in which the electron and muon sectors are decoupled, and leptoquark couplings are assigned complex values. Adopting the coupling ansatz that the electron dipole operator is generated by charm-containing loops, and muon dipole operator by top-containing loops, we find that both minimal leptoquark models remai…
The new LHCb beauty-strange state as the bottom partner of the $D_{s0}^*(2317)$: a LQCD constrained coupled-channel chiral analysis
Instituto de Física Corpuscular, Centro Mixto Universidad de Valencia-CSIC（瓦伦西亚大学-西班牙国家研究委员会联合物理粒子研究所）；Departamento de Física Teórica and IFIC, Centro Mixto Universidad de Valencia-CSIC（瓦伦西亚大学-西班牙国家研究委员会联合理论物理系及IFIC）
We investigate a dimension five Lorentz-violating (LV) nonminimal coupling between the neutral vector meson field strength and the pion current in the context of the Kroll-Lee-Zumino (KLZ) model. In this modified model we study the vector meson dominance (VMD) through of the imposing of new universality conditions between the couplings that comes from LV contributions. We also show that the LV nonminimal coupling leads to a linear momentum dependence in the timelike pion form factor, that is used to evaluate LV corrections for the muon anomalous magnetic moment. The experimental imprecision of…
We investigate the possibility of satisfying the $SU(5)$ boundary condition $\mathbf{Y}^d=\mathbf{Y}^{e\,T}$ at the GUT scale within the renormalizable $R$-parity conserving Minimal Supersymmetric Standard Model (MSSM). Working in the super-CKM basis, we consider non-zero flavour off-diagonal entries in the soft SUSY-breaking mass matrices and the $A$-terms. At the same time, the diagonal $A$-terms are assumed to be suppressed by the respective Yukawa couplings. We show that a non-trivial flavour structure of the soft SUSY-breaking sector can contribute to achieving precise Yukawa coupling uni…
We derive the eikonal equation of light wavefront in the presence of Lorentz invariance violation (LIV) from the photon sector of the standard model extension (SME). The results obtained from the equations of $\mathbf{E}$ and $\mathbf{B}$ fields respectively are the same. This guarantees the self-consistency of our derivation. We adopt a simple case with only one non-zero LIV parameter as an illustration, from which we find two points. One is that, in analogy with Hamilton-Jacobi equation, from the eikonal equation, we can derive dispersion relations which are compatible with results obtained …
We review some selected topics in the decays of heavy flavours, beauty and charm, which are of principal interest at HERA-B and HERA. The topics in $B$ physics include: an update on the quark mixing matrix and CP violating phases, issues bearing on an improved resolution on the CP-violating phase $Δ(sin 2 β)$, prospects of measuring radiative and semileptonic rare $B$ decays, the $B_s^{0}$ - $\overline{B_s^{0}}$ mixing ratio $x_s$, improved measurements of the $B_d^{0}$ - $\overline{B_d^{0}}$ mixing ratio $x_d$ and the $B$-hadron lifetimes, in particular $τ(Λ_b)$. In the charm sector, we have …
Heavy meson pairs produced in the decays of heavy quarkonium resonances at e+ e- machines (beauty and tau-charm factories) have the useful property that the two mesons are in the CP-correlated states. By tagging one of the mesons as a CP eigenstate, a lifetime difference of heavy neutral meson mass eigenstates width difference may be determined by measuring the leptonic branching ratio of the other meson. We discuss the use of this and related methods both in the case where time dependent mixing is small and when it is significant. We consider the impact of possible CP-violating effects and pr…
In a large class of SUSY GUT models with see-saw mechanism of neutrino mass generation, lepton flavor violating (LFV) decays $μ\to e + γ$, $τ\to μ+ γ$, etc., are predicted with rates that are within the reach of present and planned experiments. A crucial element in these predictions is the matrix of neutrino Yukawa couplings $\ynu$ which can be expressed in terms of the light and RH heavy neutrino masses, the neutrino mixing PMNS matrix $U$, and an orthogonal matrix $\mathbf{R}$. Leptogenesis can take place only if $\mathbf{R}$ is complex. Considering the case of quasi-degenerate neutrinos and…
The decay process $B\to D^+ D^- π^0$ is an interesting channel for the investigation of CP violating effects in the $b-$ sector. We write down a decay amplitude constrained by a low-energy theorem, which also includes the contribution of resonant $S-$ and $P-$wave beauty and charmed mesons, and we determine the relevant matrix elements in the infinite heavy quark mass limit, assuming the factorization ansatz. We estimate the rate of the decay: ${\cal B}(B \to D^+ D^- π^0)\simeq 1 \times 10^{-3}$. We also analyze the time-independent and time-dependent differential decay distributions, concludi…
The charm quark offers interesting opportunities to cross-check the mechanism of CP violation precisely tested in the strange and beauty sectors. In this paper, we exploit the angular and quantum correlations in the D\bar{D} pairs produced through the decay of the psi(3770) resonance in a charm factory to investigate CP-violation in two different ways. We build CP-violating observables in psi(3770) -> D\bar{D} -> (V_1V_2)(V_3 V_4) to isolate specific New Physics effects in the charm sector. We also consider the case of psi(3770) -> D\bar{D} -> (V_1V_2)(Kπ) decays, which provide a new way to me…
Boosted Odds: Lower-Point Probes of Parity Violation with Momentum Fields
University of Cambridge（剑桥大学）；Kavli Institute for Cosmology Cambridge（剑桥卡弗里宇宙学研究所）；University of Oxford（牛津大学）；Ludwig-Maximilians-Universität（路德维希-马克西米利安大学（慕尼黑大学））；Institute of Astronomy, University of Cambridge（剑桥大学天文研究所）
CP violation is an excellent tool for probing flavor dynamics as we learnt first with $K_L \to 2 π$ and later also with the weak decays of beauty mesons. LHCb 2019 data have shown CP violation for the first time in $D^0\to K^-K^+$ vs. $D^0\toπ^-π^+$. Searching for CP asymmetries is of great interest in charm quark sector in the Standard Model (SM) or even more beyond it. In charm hadron decays, lots of work had focused on two-body final states, and the measurements of CP asymmetries in three- or four-body final states are rare. Dalitz plots have shown an excellent record for three-body final s…
To explain the dark matter and the baryon asymmetry of the Universe, the parameters of the $ν$MSM (an extension of the Minimal Standard Model by three singlet neutrinos with masses smaller than the electroweak scale) must be fine-tuned: one of the masses should be in the ${\cal O} (10)$ keV region to provide a candidate for the dark-matter particle, while two other masses must be almost the same to enhance the CP-violating effects in the sterile neutrino oscillations leading to the baryon asymmetry. We show that a specifically defined global lepton-number symmetry, broken on the level of ${\ca…
Electroweak Transitions of Hyperons and Charmed Baryons: Opportunities and Prospects
Uppsala University（乌普萨拉大学）；National Centre for Nuclear Research（国家核研究中心）；University of Cyprus（塞浦路斯大学）；The Cyprus Institute（塞浦路斯研究所）；Institute of High Energy Physics（高能物理研究所）；Lund University（隆德大学）；École Polytechnique Fédérale de Lausanne（洛桑联邦理工学院）；University of Graz（格拉茨大学）
