Institute for Nuclear Theory, University of Washington（华盛顿大学核理论研究所）；Northwestern University（西北大学）；KEK Theory Center, IPNS, KEK（高能加速器研究机构理论中心）；Theoretical Division, Los Alamos National Laboratory（洛斯阿拉莫斯国家实验室理论部）
我们探讨了通过重中性轻子（HNL）的共振产生，在电子离子对撞机（EIC）上探测风味性轻子数不守恒的前景，结果为$e^- p \to \ell^+_α+ k\, j+X$，其中$α\in \{e, μ, τ\}$，$k$表示喷注数量。我们基于标准模型有效场论（SMEFT）并加入$n$个单态HNL的框架进行研究，其中有一个HNL的质量范围为$10-100$~GeV，在EIC的动量学范围内。为了探索EIC的灵敏度，我们专注于由与轻轻子混合引起的HNL产生机制。我们研究了信号和背景的动量学分布，包括hadronization和探测器效应，并建议了一组切割以最小化背景。在考虑的质量范围内，我们发现EIC配备muon探测能力并具有$100~\mathrm{fb}^{-1}$的积分亮度时，可以达到与最强直接（LHC）和间接约束相当的灵敏度，并且在$ν$SMEFT框架中超越四维。我们的研究促使进一步评估EIC的muon探测能力以及$τ$强子重建，以及更一般的理论分析，涉及由高维算符介导的产生机制。
英文摘要：
We explore the prospects of detecting flavorful lepton number violation at the Electron-Ion Collider (EIC) through resonant production of heavy neutral leptons (HNLs), resulting in $e^- p \to \ell^+_α+ k\, j+X$, where $α\in \{e, μ, τ\}$ and $k$ denotes the number of jets. We work in the $ν$SMEFT framework of the Standard Model Effective Field Theory augmented with $n$ singlet HNLs, one of which is in the mass range $10-100$~GeV, within kinematic reach of the EIC. To explore the EIC sensitivity, we focus on the HNL production mechanism induced by mixing with light neutrinos. We study kinematic distributions for signal and backgrounds, including hadronization and detector effects, and suggest a set of cuts to minimize backgrounds. In the mass range considered, we find that the EIC with muon detection capabilities and an integrated luminosity of $100~\mathrm{fb}^{-1}$ can reach sensitivities comparable to the strongest direct (LHC) and indirect constraints, and is especially relevant in the $ν$SMEFT framework beyond dimension four. Our study motivates further assessment of muon detection capabilities at the EIC and $τ$ hadronic reconstruction, as well as a more general theoretical analysis involving production mechanisms mediated by higher-dimensional operators in the effective theory.
We consider a fifth force to be an interaction that couples to matter with a strength that grows with the number of atoms. In addition to competing with the strength of gravity a fifth force can give rise to violations of the equivalence principle. Current long range constraints on the strength and range of fifth forces are very impressive. Amongst possible fifth forces are those that couple to lepton flavorful charges $L_e-L_μ$ or $L_e-L_τ$. They have the property that their range and strength are also constrained by neutrino interactions with matter. In this brief note we review the existing…
Relaxing Constraints from Lepton Flavor Violation in 5D Flavorful Theories
我们提出了新的机制，改善的卡鲁扎-克莱因（KK）质量标度的约束带电轻子味破坏的标准模型（SM）的框架内传播的一个扭曲的额外的维度，特别是在模型占中微子数据。这些机制利用了扩展的五维（5D）电弱规范对称性[SU（2）_L x SU（2）_R x U（1）_X]，为了满足该框架中的电弱精确测试，该规范对称性已经被强烈地激发。在这种对称性下，轻子表示的新选择（自然地）可以允许左手（LH）带电轻子的小混合角，同时允许它们的SU（2）_L伙伴的大混合角，即，LH中微子，中微子数据被占后者的混合。因此，在这些模型中，可以避免由在轻子带电电流中观察到的大混合角引起的带电轻子味违反的增强，该混合角存在于LH带电轻子和中微子混合角相似的表示的最小选择中。这个想法也可能是有用的抑制贡献B_{d, s}混合在这个框架中，为了抑制味道违反超伴侣（而不是从KK模式）在5D“美味超对称”模型。此外，较少的最小表示可以为费米子与Z的耦合转移提供监护保护，进而进一步抑制在扭曲的额外维度场景中来自树级Z交换的带电轻子味道违反。结果表明，即使在弯曲额外维的框架下，~O（3）TeV KK质量标度的5D味参数没有任何特殊结构，也能同时与带电轻子味破坏和中微子数据相一致。
Flavorful Lepton-Number-Violating SMEFT: Loop Mixing, $0νββ$ and Rare Meson Decays
Institute of Particle and Nuclear Physics (IPNP), Faculty of Mathematics and Physics, Charles University in Prague（布拉格查理大学数学物理学院粒子与核物理研究所）；Institute of Physics, Silesian University in Opava（奥帕瓦西里西亚大学物理研究所）；Instituto de Física Corpuscular (IFIC), Universitat de València–CSIC（巴伦西亚大学-西班牙国家科学研究委员会粒子物理研究所）；Department of Physics, University of California, Berkeley（加州大学伯克利分校物理学系）
We address the presently reported significant flavor anomalies in the Kaon and $B$ meson systems such as the CP violating Kaon decay ($ε'/ε$) and lepton-flavor universality violation in $B$ meson decays ($R_{K^{(*)}},{R_{D^{(*)}}}$), by proposing flavorful and chiral vector bosons as the new physics constitution at around TeV scale. The chiral-flavorful vectors (CFVs) are introduced as a 63-plet of the global $SU(8)$ symmetry, identified as the one-family symmetry for left-handed quarks and leptons in the standard model (SM) forming the 8-dimensional vector. Thus the CFVs include massive gluon…
$B$-physics data and flavor symmetries suggest that leptoquarks can have masses as low as few ${\cal{O}}(\mbox{TeV})$, predominantly decay to third generation quarks, and highlight $pp \to b μμ$ signatures from single production and $pp \to b b μμ$ from pair production. Abandoning flavor symmetries could allow for inverted quark hierarchies, and cause sizable $pp \to j μμ$ and $jj μμ$ cross sections, induced by second generation couplings. Final states with leptons other than muons including lepton flavor violation (LFV) ones can also arise. The corresponding couplings can also be probed by pr…
We present a comprehensive analysis of the potential sensitivity of the Electron-Ion Collider (EIC) to charged lepton flavor violation (CLFV) in the channel $ep\to τX$, within the model-independent framework of the Standard Model Effective Field Theory (SMEFT). We compute the relevant cross sections to leading order in QCD and electroweak corrections and perform simulations of signal and SM background events in various $τ$ decay channels, suggesting simple cuts to enhance the associated estimated efficiencies. To assess the discovery potential of the EIC in $τ$-$e$ transitions, we study the se…
Any axionlike particle (ALP) intrinsically possesses flavorful couplings to the standard model (SM) fermions arising as a consequence of the right-handed flavor rotation within the SM. In this paper we discuss this intrinsically flavored ALP, and explore the correlation of a minimal set of the couplings in a view of coherence in flavor physics observables. We focus particularly on the tau-lepton flavor violation (LFV). The ALP is assumed to be tau-philic on a current-eigenstate basis, a la Pecci-Quinn. The ALP has the intrinsic flavorful coupling structure for fermions, which allows coupling a…
We investigate collider signatures of standard model extensions featuring vector-like leptons and a flavorful scalar sector. Such a framework arises naturally within asymptotically safe model building, which tames the UV behavior of the standard model towards the Planck scale and beyond. We focus on values of Yukawa couplings and masses which allow to explain the present data on the muon and electron anomalous magnetic moments. Using a CMS search based on $77.4 \, \rm{fb}^{-1}$ at the $\sqrt{s}=13$ TeV LHC we find that flavorful vector-like leptons are excluded for masses below around $300$ Ge…
The flavorful $Z^\prime$ model with its couplings restricted to the left-handed second generation leptons and third generation quarks can potentially resolve the observed anomalies in $R_K$ and $R_{K^*}$. After examining the current limits on this model from various low-energy processes, we probe this scenario at 14 TeV high-luminosity run of the LHC using two complementary channels: one governed by the coupling of $Z'$ to $b$-quarks and the other to muons. We also discuss the implications of the latest LHC high mass resonance searches in the dimuon channel on the model parameter space of our …
We calculate cross sections for inclusive dijet photoproduction in electron-nucleus scattering in the kinematics of the future EIC and the possible LHeC, HE-LHeC, and the FCC using next-to-leading order (NLO) perturbative QCD and nCTEQ15 and EPPS16 nuclear parton density functions (nPDFs). We make predictions for distributions in the dijet average transverse momentum ${\bar p}_T$, the average rapidity $\barη$, the observed nuclear momentum fraction $x_A^{\rm obs}$, and the observed photon momentum fraction $x_γ^{\rm obs}$. Comparing the kinematic reaches of the four colliders, we find that an …
In this whitepaper, we consider the model of heavy neutral leptons (HNLs) as an example to explore the potential of new physics searches at the Electron-Ion Collider (EIC). We propose two broad categories of search strategies depending on the HNL lifetime: direct searches for the prompt decay of HNLs with a short lifetime and displaced vertex searches for long-lived ones. After identifying the most promising signals and the corresponding backgrounds, we perform a detailed simulation to estimate the sensitivity of the EIC to HNLs, accounting for detector thresholds, resolutions, and geometric a…
The dark photon is widely predicted in many new physics beyond the Standard Model. In this work, we propose to utilize the polarized lepton cross section in neutral current DIS process at the HERA and upcoming Electron-Ion Collider (EIC) to probe the properties of the dark photon. It shows that we can constrain the mixing parameter $ε<0.02$ when the dark photon mass $m_{A_D}<10 ~{\rm GeV}$ at the HERA with polarized lepton beam and this bound is comparable to the limit from the unpolarized HERA data. With the help of high integrated luminosity and high electron beam polarization of the EIC, th…
The future Electron-Ion Collider (EIC) at Brookhaven National Laboratory, along with its primary capacity to elucidate the nuclear structure, will offer new opportunities to probe physics beyond the Standard Model coupled to the electroweak sector. Among the best motivated examples of such new physics are new heavy neutral leptons (HNLs), which are likely to play a key role in neutrino mass generation and lepton number violation. We study the capability of the EIC to search for HNLs, which can be produced in electron-proton collisions through charged current interactions as a consequence of th…
We study the potential for precision electroweak (EW) measurements and beyond-the-Standard Model (BSM) searches using cross-section asymmetries in neutral-current (NC) deep inelastic scattering at the electron-ion collider (EIC). Our analysis uses a complete and realistic accounting of systematic errors from both theory and experiment and considers the potential of both proton and deuteron beams for a wide range of energies and luminosities. We also consider what can be learned from a possible future positron beam and a potential ten-fold luminosity upgrade of the EIC beyond its initial decade…
The upcoming Electron-Ion Collider (EIC) will address several outstanding puzzles in modern nuclear physics. Topics such as the partonic structure of nucleons and nuclei, the origin of their mass and spin, among others, can be understood via the study of high energy electron-proton ($ep$) and electron-nucleus ($e$A) collisions. Achieving the scientific goals of the EIC will require a novel electron-hadron collider and detectors capable to perform high-precision measurements, but also dedicated tools to model and interpret the data. To aid in the latter, we present a general-purpose $e$A Monte …
We study the diffractive jet production in electron-ion collisions in the kinematical region where the mass $M_X$ of the diffractive final state is larger than $Q^2$. Based on parton saturation framework predictions are done for the kinematics of future or possible $eA$ machines as the EIC, LHeC, HE-LHeC and FCC-eA. We analyze the differential cross section as a function of jet (gluon) transverse momentum and from the experimental point of view this observable could be used to extract the saturation scale as a function of $x_{I\!\!P}$.
Gluon Generalized TMD signatures at the EIC from exclusive heavy (axial-)vector meson production
University of Connecticut（康涅狄格大学）；Shandong University（山东大学）；Shandong Institute of Advanced Technology（山东高等技术研究院）；Institute of Modern Physics, Chinese Academy of Sciences（中国科学院近代物理研究所）
Charged lepton flavor violation has long been recognized as unambiguous signature of New Physics. Here we describe the physics capabilities and discovery potential of New Physics models with charged lepton flavor violation in the tau sector as its experimental signature. Current experimental status from the B-Factory experiments BaBar, Belle and Belle II, and future prospects at Super Tau Charm Factory, LHC, EIC and FCC-ee experiments to discover New Physics via charged lepton flavor violation in the tau sector are discussed in detail. Submitted to the Proceedings of the US Community Study on …
We quantify the impact of unpolarized lepton-proton and lepton-nucleus inclusive deep-inelastic scattering (DIS) cross section measurements from the future Electron-Ion Collider (EIC) on the proton and nuclear parton distribution functions (PDFs). To this purpose we include neutral- and charged-current DIS pseudodata in a self-consistent set of proton and nuclear global PDF determinations based on the NNPDF methodology. We demonstrate that the EIC measurements will reduce the uncertainty of the light quark PDFs of the proton at large values of the momentum fraction $x$, and, more significantly…
Diffractive Production of Heavy Quarkonia at the Electron Ion Collider
Central China Normal University（华中师范大学）；University of Wrocław（弗罗茨瓦夫大学）；West University of Timişoara（蒂米什瓦拉西部大学）；Indian Institute of Technology Goa（印度理工学院果阿分校）
