New physics at high energy scale often contributes to K-\bar K and D-\bar D mixings in an approximately SU(2)_L invariant way. In such a case, the combination of measurements in these two systems is particularly powerful. The resulting constraints can be expressed in terms of misalignments and flavor splittings.
The Quark Flavor Violating Higgs Decay $h \rightarrow \bar b s + b \bar s$ in the MSSM
研究了最小超对称标准模型中夸克味破坏的Higgs玻色子衰变$h \rightarrow \bar b s + b \bar s$.首先在独立模型中分析衰减，然后在第二步中在最小味道违反（MFV）约束MSSM中分析衰减。从$B$ -物理观测量（BPO）和电弱精密观测量（EWPO）的实验约束也计算和施加在参数空间。结果表明，在某些情况下，EWPO比BPO更强地限制了味道违反参数空间。在模型中，可找到${\rm BR}(h \rightarrow \bar b s + b \bar s)$的${\cal O}(10^{-4})$独立分析值。在MFV CMSSM中，这样的结果只能在参数空间的非常有限的部分中获得。结果表明，不排除在未来的$e^+e^-$对撞机上观察到MSSM中的$h \rightarrow \bar b s + b \bar s$衰变。
Are there narrow flavor-exotic tetraquarks in large-$N_c$ QCD?
在实验中观察到的所有四夸克候选者的一个显著特征是没有$\bar a b\bar c d$类型的味道奇异态，有四种不同的夸克味道。这种现象可以从大- $N_c$量子色动力学的性质来理解：一方面，味奇异格林函数的相容性条件，可能包含这些四夸克极点，需要存在两个四夸克$T_A$和$T_B$：它们中的每一个都应该通过一个单一的双介子通道，$T_A\to M_{\bar a b}M_{\bar c d}$和$T_B\to M_{\bar a d}M_{\bar c b}$，以抑制的速率$T_A\to M_{\bar a d}M_{\bar c b}$和$T_B\to M_{\bar a b}M_{\bar c d}$衰变。另一方面，我们手头只有一个双夸克-反双夸克味结构$(\bar a \bar c)(b d)$，它可能产生一个紧凑的四夸克束缚态。考虑到双夸克-反双夸克结构是紧致四夸克态唯一可行的候选者，我们得出结论，不可能有两个不同的窄四夸克主要衰变到不同的两介子通道。这种矛盾表明大$N_c$ QCD不支持窄味奇异四夸克的存在。这个论点并不排除可能存在的广泛分子型风味异国情调的国家，或分子型的束缚态躺在非常接近两个介子阈值。
$SU(2)_L$-invariance links charged dilepton $\bar q\,q^\prime\,\ell^+\,\ell^-$ and dineutrino $\bar q\, q^\prime\, \barν\,ν$ couplings. This connection can be established using the Standard Model Effective Field Theory framework, and allows to perform complementary experimental tests of lepton universality and charged lepton flavor conservation with flavor-summed dineutrino observables. We present its phenomenological implications for the branching ratios of rare charm decays $c\to u\,ν\,\barν$ and rare $B$ decays $b\to s\,\barν\,ν$ decays.
Flavor asymmetry of polarized antiquark distributions and semi-inclusive DIS
QCD的$1/N_c$ -展开式表明核子中极化反夸克分布的大味不对称性。这是证实了在大$N_c$极限（手征夸克孤子模型），这给出了相当大的结果$Δ\bar u (x) - Δ\bar d (x)$和$Δ\bar u (x) + Δ\bar d (x) - 2 Δ\bar s (x)$模型计算。我们计算了这些味不对称性的贡献，在强子生产的自旋不对称性在半包容的深度非弹性散射。我们表明，大味不对称性预测的手征夸克孤子模型是一致的，与最近的HERMES数据的自旋不对称性带电强子生产。
We compute the light antiquark flavor asymmetry in the proton using the Chiral Quark Model ($χ_{\rm QM}$). The distribution functions for the light antiquarks $\bar{d}(x)$ and $\bar{u}(x)$ have been extracted with the help of experimental data from NuSea/E866 and HERMES for the Bjorken$-x$ range $0.015 < x < 0.35$ as well from the most recent SeaQuest data for an extended $x$ range $0.13 < x < 0.45$. Our results on the $\bar{d}(x)-\bar{u}(x)$, $\frac{\bar{d}(x)}{\bar{u}(x)}$ and Gottfried Integral $I_G$ are in agreement with the experimental data and confirm the presence of enhanced $\bar{d}$ …
Matter-enhanced antineutrino flavor transformation and supernova nucleosynthesis
如果$\barν_e$和$\barν_{μ(τ)}$的真空质量满足$m_{\barν_e}>m_{\barν_{μ(τ)}}$，那么在超新星中可以发生物质增强的反中微子味转换。对于$δm^2> 1$ eV $^2$，这种风味转变可能会影响中微子加热的超新星喷出物中的电子分数$Y_e$。我们指出，这样的味道转换将不会驱动$Y_e>0.5$在$r$过程的核合成时代，在最好的超新星模型，这样的核合成。因此，在中微子加热的超新星喷出物中，物质增强的反中微子味转换$\barν_e\rightleftharpoons\barν_{μ(τ)}$和$r$过程的核合成之间没有明显的冲突。
We study the impact of SU(3) flavor symmetry breaking on the properties of dynamically generated $Λ^*$ states within an effective separable potential model describing the coupled channels $\bar{K}N$ system. The model is based on the chiral meson-baryon Lagrangian at next-to-leading order, and constitutes an improvement over a previous model developed by our group, with its applicability being extended to higher energies covering the $Λ(1670)$ resonance region. It is demonstrated that the ratios of channel couplings to the resonant states can vary dramatically when the flavor breaking is gradua…
The LHCb Collaboration has reported resonant activity in the channel $D^+ K^-$, identifying two components: $X_0(2900)$ with $J^P = 0^+$ at $2866 {\pm} 7$ MeV, $Γ_0=57{\pm} 13$ MeV and $X_1(2900)$ with $J^P = 1^-$ at $2904 {\pm} 7$ MeV, $Γ_1=110{\pm} 12$ MeV. We interpret the $X_0(2900)$ component as a $cs \bar u\bar d$ isosinglet compact tetraquark, calculating its mass to be $2863 {\pm} 12$ MeV. This is the first exotic hadron with open heavy flavor. The analogous $bs\bar u\bar d$ tetraquark is predicted at $6213 {\pm} 12$ MeV. We discuss possible interpretations of the heavier and wider $X_…
The discovery of three pentaquark peaks -- the $P_c(4312)$, $P_c(4440)$ and $P_c(4457)$ -- by the LHCb collaboration has a series of interesting consequences for hadron spectroscopy. If these hidden-charm objects are indeed hadronic molecules, as suspected, they will be constrained by heavy-flavor and SU(3)-flavor symmetries. The combination of these two symmetries will imply the existence of a series of five-flavor pentaquarks with quark content $\bar{b} c s d u$ and $b \bar{c} s d u$, that is, pentaquarks that contain each of the five quark flavors that hadronize. In addition, from SU(3)-fla…
We analyze $K\to πν\bar ν$ rates in a model with a TeV-scale leptoquark addressing $B$-meson anomalies, based on the flavor non-universal 4321 gauge group featuring third-generation quark-lepton unification. We show that, together with the tight bounds imposed by $ΔF = 2$ amplitudes, the present measurement of $\mathcal{B}(K^+ \to π^+ ν\barν)$ already provides a non-trivial constraint on the model parameter space. In the minimal version of the model, the deviations from the Standard Model in $\mathcal{B}(K^+ \to π^+ ν\barν)$ are predicted to be in close correlation with non-standard effects in…
Implications of Flavor Symmetries for Baryon Number Violation
Institut de Física Corpuscular (IFIC), Consejo Superior de Investigaciones Científicas (CSIC) and Universitat de València (UV)（粒子物理研究所（IFIC），西班牙国家科研理事会（CSIC）和瓦伦西亚大学（UV)）；Department of Physics, University of Basel（巴塞尔大学物理系）；Istituto Nazionale di Fisica Nucleare, Sezione di Padova（意大利国家核物理研究所帕多瓦分部）；Dipartimento di Fisica e Astronomia ”Galileo Galilei”, Università di Padova（帕多瓦大学伽利略·伽利莱物理与天文系）；Physik-Institut, Universität Zürich（苏黎世大学物理学院）
Baryogenesis via the CKM Matrix with Minimal Flavor Violation
Northwestern University（西北大学）；Fermilab（费米国家加速器实验室）；Virginia Polytechnic Institute and State University（弗吉尼亚理工大学）；University of Chicago（芝加哥大学）；Massachusetts Institute of Technology（麻省理工学院）；Boston University（波士顿大学）；Harvard University（哈佛大学）
