B -> K* 11角观测量已成为b->s跃迁的全局模型无关分析的关键成分。然而，随着实验精度的提高，使用理论上干净的数量成为一个关键问题。使用集成在小箱子中的清洁可观测数据的全球分析已经成为现实，为我们探索新物理学开辟了新的篇章。
英文摘要：
B -> K*ll angular observables have become a key ingredient in global model-independent analyses of b->s transitions. However, as experimental precision improves, the use of theoretically clean quantities becomes a crucial issue. Global analyses that use clean observables integrated in small bins are already a reality, opening up a new chapter in our quest for New Physics.
Generalized parton distributions describe the correlations between the longitudinal momentum and the transverse position of quarks and gluons in a nucleon. They can be constrained by measuring photon leptoproduction observables, arising from the interference between Bethe-Heitler and Deeply virtual Compton scattering processes. At leading-twist/leading-order, the amplitude of the latter is parameterized by complex integrals of the GPDs {H, E, H, E} . As data collected on an unpolarized or longitudinally polarized target constrains H and H, E is poorly known as it requires data collected with a…
We analyze the angular distributions of B -> K^* (-> K pi) l^+ l^- and B -> K l^+ l^- decays in the region of low hadronic recoil in a model-independent way by taking into account the complete set of dimension-six operators [sbar Gamma b][lbar Gamma' l]. We obtain several novel low-recoil observables with high sensitivity to non-standard-model Dirac structures, including CP-asymmetries which do not require flavor tagging. The transversity observables H_T^(1,3,4,5) are found to be insensitive to hadronic matrix elements and their uncertainties even when considering the complete set of operators…
\textsc{Jewel} is a fully dynamical event generator for jet evolution in a dense QCD medium, which has been validated for multiple jet and jet-like observables. Jet constituents (partons) undergo collisions with thermal partons from the medium, leading to both elastic and radiative energy loss. The recoiling medium scattering centers carry away energy and momentum from the jet. Keeping track of these recoils is essential for the description of intra-jet observables. Since the thermal component of the recoils is part of the soft background activity, comparison with data on jet observables requi…
We probe the rare semileptonic decays $B_{(s)} \to K_2^*(1430)(f_2'(1525)) \ell^+\ell^-$ proceeding via $b\to s \ell \ell$ transition in the presence of a light $Z^{\prime}$ boson. We employ the presence of an additional vector type interaction and constrain the new physics coupling parameter using the existing experimental measurements on $R_K$ and $R_{K^*}$ observables. To understand the sensitivity of the new physics coupling, we investigate the impact of this coupling on various physical observables such as differential branching ratio, the forward-backward asymmetry, the lepton polarizati…
We critically examine the potential to disentangle Standard Model (SM) and New Physics (NP) in $B \to K^* μ^+μ^-$ and $B\to K^* e^+ e^-$ decays, focusing on $(i)$ the LHCb anomaly, $(ii)$ the search for right-handed currents, and $(iii)$ lepton-universality violation. Restricting ourselves to the large-recoil region, we advocate a parameterisation of the hadronic matrix elements that separates model-independent information about nonperturbative QCD from the results of model calculations. We clarify how to estimate corrections to the heavy-quark limit that would generate a right-handed (virtual…
On the impact of power corrections in the prediction of B->K*mu+mu- observables
最近对排他性衰变B-> K ^* mu + mu-的LHCb角分析表明，与标准模型的预期有很大的偏差。对于一组优化的观测量，在α_s的首阶重夸克极限下对强子输入不敏感，可以在大的K~*介子反冲下得到精确的预言。然而，强子不确定性通过非微扰的Lambda_QCD/m_b功率修正重新出现，这必须被精确地评估。在QCD因式分解的框架内，我们提出了一个系统的方法，包括因式功率校正，并指出，它们对角可观测量的影响取决于选择的方案来定义软形状因子。与文献中早期的说法相反，相关的不确定性已得到控制。我们还讨论了可能的非因子分解功率校正的影响，包括估计的魅力循环效应。我们提供了两套不同的形状因子的输入，在大反冲角可观的结果，阐明了不同的理论不确定性的来源。最后，我们评论了最近的建议，解释异常的B-> K * mu + mu-观测通过魅力共振效应，我们提出了策略来测试这个建议，确定观测和运动学区域的魅力环模型可以从新物理效应或两个选项留下不同的印记。
We critically reassess the theoretical uncertainties in the Standard Model calculation of the $B \to K^* \ell^+ \ell^-$ observables, focusing on the low $q^2$ region. We point out that even optimized observables are affected by sizable uncertainties, since hadronic contributions generated by current-current operators with charm are difficult to estimate, especially for $q^2 \sim 4 m_c^2\simeq 6.8$ GeV$^2$. We perform a detailed numerical analysis and present both predictions and results from the fit obtained using most recent data. We find that non-factorizable power corrections of the expecte…
The effect of recoils on soft-drop-groomed observables in $γ$-tagged jets in a multistage approach
Akita International University（秋田国际大学）；Duke University（杜克大学）；Wayne State University（韦恩州立大学）；Lawrence Livermore National Laboratory（劳伦斯利弗莫尔国家实验室）；Vanderbilt University（范德堡大学）；Massachusetts Institute of Technology（麻省理工学院）；McGill University（麦吉尔大学）；University of California, Berkeley（加州大学伯克利分校）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）
We derive an operator based factorization theorem for the energy-energy correlation (EEC) observable in the back-to-back region, allowing the cross section to be written as a convolution of hard, jet and soft functions. We prove the equivalence of the soft functions for the EEC and color singlet transverse-momentum resummation to all-loop order, and give their analytic result to three-loops. Large logarithms appearing in the perturbative expansion of the EEC can be resummed to all orders using renormalization group evolution. We give analytic results for all required anomalous dimensions to th…
We elaborate on the dichotomy between the description of the semileptonic decays of heavy hadrons on the one hand and the semileptonic decays of light hadrons such as neutron $β$ decays on the other hand. For example, almost without exception the semileptonic decays of heavy baryons are described in cascade fashion as a sequence of two two-body decays $B_1 \to B_2 + W_{\rm off-shell}$ and $W_{\rm off-shell} \to \ell + ν_\ell$ whereas neutron $β$ decays are analyzed as true three-body decays $n \to p + e^- +\bar ν_e$. Within the cascade approach it is possible to define a set of seven angular o…
We study the differential decay rate for the rare $Λ_b \to Λ(\to N π)\ell^+\ell^-$ transition, including a determination of the complete angular distribution, assuming unpolarized $Λ_b$ baryons. On the basis of a properly chosen parametrization of the various helicity amplitudes, we provide expressions for the angular observables within the Standard Model and a subset of new physics models with chirality-flipped operators. Hadronic effects at low recoil are estimated by combining information from lattice QCD with (improved) form-factor relations in Heavy Quark Effective Theory. Our estimates f…
Key features of jet-medium interactions in heavy-ion collisions are modifications to the jet structure. Recent results from experiments at the LHC and RHIC have motivated several theoretical calculations and monte carlo models towards predicting these observables simultaneously. In this report, the recoil picture in \textsc{Jewel} is summarized and two independent procedures through which background subtraction can be performed in \textsc{Jewel} are introduced. Information of the medium recoil in \textsc{Jewel} significantly improves its description of several jet shape measurements.
Based on the renormalization group summation method of McKeon ${\it et\; al.}$, it is shown that the renormalization group equation, while related to the radiatively mass scale $μ$, would perform a summation over QCD perturbative terms. Employing the full QCD $β$-function within this summation, all logarithmic corrections can be presented as log-independent contributions. In another step of this approach, the renormalization scheme dependence of QCD observables, characterized by Stevenson, is required to be examined. In this regard, two choices of renormalization scheme would be exposed. In on…
We use machine learning (ML) and non-ML techniques to study optimized $CP$-odd observables, directly and maximally sensitive to the $CP$-odd $i \tilde κ\bar t γ^5 t h$ interaction at the LHC and prospective future hadron colliders using the final state with a Higgs boson and a top quark pair, $pp\to t\bar t h$, followed by semileptonic $t$ decays. We perform phase-space optimization of manifestly $CP$-odd observables ($\boldsymbol ω$), sensitive to the sign of $\tilde κ$, and constructed from experimentally accessible final state momenta. We identify a simple optimized linear combination $\bol…
The flavor changing rare decay $B\to K^{*}(\to Kπ)\ell^+\ell^-$ is one of the most studied modes due to its sensitivity to physics beyond the standard model and several discrepancies have come to light among the plethora of observables that are measured. In this paper we revisit the analogous baryonic decay mode $Λ_{b}\rightarrow Λ(\to pπ) \ell^{+}\ell^{-}$ and we present a complete set of ten angular observables that can be measured using this decay mode. Our calculations are done retaining the finite lepton mass so that the signal of lepton non-universality observed in $B\to K^{*} \ell^+\ell…
We derive an all-order factorization theorem for the narrow jet broadening event shape, a measure of the transverse momentum in jet events. This is a non-global observable which receives logarithmically enhanced contributions associated with the large rapidity difference between soft and collinear radiation and which is also sensitive to soft recoil effects. Our work is the first factorization analysis of an observable of this type and we show that with regard to the non-global nature, the rapidity logarithms do not constitute an essential complication since they can be tied to the jet functio…
Tracing Gluon Saturation through Hadronization at EIC
Central China Normal University（华中师范大学）；Institute of Modern Physics, Chinese Academy of Sciences（中国科学院近代物理研究所）；Shandong University（山东大学）；École Polytechnique, Institut Polytechnique de Paris（巴黎理工学院巴黎综合理工学校）
Determining pseudoscalar meson photo-production amplitudes from complete experiments
我们回顾了最一般的截面解析形式的发展，它依赖于束、靶和反冲重子的三个极化矢量，包括所有的单、双和三极化项，涉及16个自旋相关的观测量。我们研究了不同的公约，已被不同的作者，我们提出的表达式，允许直接数值计算的任意自旋投影的任意赝标介子光生可观的Chew-Goldberger-Low-Nambu振幅。我们使用这个数值工具来澄清文献中存在的明显的符号差异。我们还提出了确定反冲重子极化的解析表达式，以及它们与准4pi探测器的潜在用途的例子来推断观测值。为了说明本综述中提出的一致机制的使用，我们对γ p -> K^+ λ反应进行了多极分析，并研究了最近发表的极化测量的影响。在拟合多极子时，我们使用了振幅空间的蒙特卡罗抽样和梯度最小化，并找到了一个由大量局部最小值构成的浅chi^2谷。这导致在实验上无法区分的多极解的宽带。虽然这些波段已被纳入新的偏振测量显着缩小，许多多极仍然非常差，即使在符号，尽管包括8个不同的观测数据。我们比较了多极从最近的PWA代码与我们的模型无关的解决方案频带。潜在的准确性，可以从所有16个偏振观测值的测量提取的振幅进行了研究与模拟数据使用的统计变化，预计从正在进行的实验。
Rare $b \to s\ell^+\ell^-$ flavour-changing-neutral-current processes provide important tests of the Standard Model of particle physics. Angular observables in exclusive $b \to s\ell^+\ell^-$ processes can be particularly powerful as they allow hadronic uncertainties to be controlled. Amongst the exclusive processes that have been studied by experiments, the decay $Λ_b\to Λ\ell^+\ell^-$ is unique in that the $Λ_b$ baryon can be produced polarised. In this paper, we derive an expression for the angular distribution of the $Λ_b\to Λ\ell^+\ell^-$ decay for the case where the $Λ_b$ baryon is produ…
