Dris Boubaa, Shaaban Khalil, Stefano Moretti
Recent measurements of certain B decays indicate deviations from Standard Model (SM) predictions. We show that Supersymmetric effects can increase the Branching Ratios (BRs) of both $B\to D τ ν_τ$ and $B\to D^\ast τ ν_τ$ with respect to the SM rates, thereby approaching their newest experimentally measured values.
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We propose a SUSY scenario to explain the current electron and muon $g-2$ discrepancies without introducing lepton flavor mixings. Threshold corrections to the Yukawa couplings can enhance the electron $g-2$ and flip the sign of the SUSY contributions. The mechanism predicts a flavor-dependent slepton mass spectrum. We show that it is compatible with the Higgs mediation scenario.
We discuss an optimal $R$-parity breaking SUSY solution to the $R_b$ excess as well as the ALEPH 4-jet anomaly. The latter arises from the pair production of stop via chargino decay at LEP1.5, followed by its $R$--violating decay into a light quark pair. The model satisfies top quark and $Z$--boson decay constraints along with gaugino mass unification.
We analyze the theory and phenomenology of anomalous global chiral symmetries in the presence of an extra dimension. We propose a simple extension of the Standard Model in 5D whose signatures closely resemble those of supersymmetry with gauge mediation, and we suggest a novel scalar dark matter candidate.
A non-universal $U(1)_{X}$ extension to the Standard Model composed of two scalar doublets and two scalar singlets together with three additional quark singlets and two lepton singlets and three generations of right-handed and Majorana neutrinos is made to explain lepton mass hierarchy, neutrino masses via inverse seesaw mechanism and muon anomalous magnetic moment in an anomaly free framework. In the present model, exotic and Standard Model particles acquire mass thanks to vacuum expectation values at different scales, yet the electron and the lightest neutrino are tree level massless but mas…
Explaining the ${\mathcal{R}}(D)$ and ${\mathcal{R}}(D^{\ast})$ Anomalies in the $B-L$ Supersymmetric Standard Model with Inverse Seesaw
本研究在带Inverse Seesaw的B-L超对称标准模型框架下，通过右手中微子等介导的轻子企鹅图，同时解释了${\mathcal{R}}(D)$和${\mathcal{R}}(D^{\ast})$两类轻子味普适性反常现象。
We consider the two Higgs doublet model (2HDM) along with a generation of vector-like lepton doublet and singlet to explain the observed discrepancies in the electron and muon anomalous magnetic moments. The type-X (lepton-specific) 2HDM can allow a light pseudo-scalar which is known to explain the muon anomalous magnetic moment at two-loop. Such a light particle induces a sizable negative contribution to the electron anomalous magnetic moment at one-loop in the presence of vector-like leptons evading all the experimental constraints.
Discrepancies between recent experimental results and their respective Standard Model predictions, known as flavour anomalies, are reported in semileptonic charged and neutral-current $B$-decays, the muon magnetic moment $(g-2)_μ$, and the extraction of the Cabibbo angle. In this proceedings, we review two New Physics models that introduce two scalar mediators at the TeV scale and aim at a combined explanation of the flavour anomalies. The first model features the leptoquarks $S_1$ and $S_3$ and provides tree level solutions to both $B$-anomalies and one-loop level solution to the anomalous $(…
The recent intriguing measurements of $R_{K}$ and $R_{K^*}$ are important hints of new physics that violates lepton universality. We analyze the semileptonic decays $b \to s \ell^+ \ell^-$ in the framework of the $B-L$ extension of Minimal Supersymmetric Standard Model (MSSM) with Inverse Seesaw (BLSSMIS). A salient feature of this model is that one of the right-handed sneutrino can be light and the neutrino Yukawa couplings are of order one. We show that the box diagram mediated by right-handed sneutrino, higgsino-like chargino, and light stop can account simultaneously for both $R_{K}$ and $…
Recently the $B$ factories BaBar and Belle as well as the LHCb experiment have reported several anomalies in the semileptonic $B$ meson decays such as $R_{K}$ and $R_{D^{(*)}}$ etc. We investigate these deviations by considering the vector leptoquarks relevant for both $b \to s l^+ l^-$ and $b \to c l \bar ν_l$ transitions. The leptoquark parameter space is constrained by using the experimentally measured branching ratios of $B_s \to l^+ l^-$, $\bar B \to X_s l^+ l^- (ν\bar ν)$ and $B_u^+ \to l^+ ν_l$ processes. Using the constrained leptoquark couplings, we compute the branching ratios, forwa…
Explaining 95 GeV Anomalies in the 2-Higgs Doublet Model Type-I
2HDM类型I模型通过两种配置解释LHC观测到的95 GeV异常现象，结合电中性标量玻色子和电荷奇玻色子的组合，提供了一种可能的解释方案。
We study the contribution of charginos and neutralinos of the Minimal SUSY extension of the Standard model (MSSM) to the 1-loop vertices ZAA, ZZA, ZZZ, and examine the related cancellation of anomalies. It is found that when the SUSY parameter μsatisfies |μ| >> M,M', m_W, the couplings of charginos and neutralinos with the gauge bosons become purely vectorial, and then their contribution to the amplitudes for ZAA, ZZA and ZZZ vanish, which implies that this sector of the MSSM does not generate a Wess-Zumino term. We evaluate also the contribution of charginos and neutralinos to the ρparameter,…
We present the dark matter extension of the minimal supersymmetric standard model by one more two component stable fermion N toward explaining the recent rising high energy positron spectrum of the PAMELA data. The needed coupling can arise in the flipped-SU(5) GUT.
We study examples of chiral four-dimensional IIB orientifolds with Scherk--Schwarz supersymmetry breaking, based on freely acting orbifolds. We construct a new Z3xZ3' model, containing only D9-branes, and rederive from a more geometric perspective the known Z6'xZ2' model, containing D9, D5 and \bar D 5 branes. The cancellation of anomalies in these models is then studied locally in the internal space. These are found to cancel through an interesting generalization of the Green--Schwarz mechanism involving twisted Ramond--Ramond axions and 4-forms. The effect of the latter amounts to local coun…
We consider new physics explanations of the anomaly in the top quark forward-backward asymmetry measured at the Tevatron, in the context of flavor conserving models. The recently measured LHC dijet distributions strongly constrain many otherwise viable models. A new scalar particle in the antitriplet representation of flavor and color can fit the t tbar asymmetry and cross section data at the Tevatron and avoid both low- and high-energy bounds from flavor physics and the LHC. An s-channel resonance in uc to uc scattering at the LHC is predicted to be not far from the current sensitivity. This …
We propose a model to explain several muon-related experimental anomalies and the abundance of dark matter. We introduce an vector-like exotic lepton that form an iso-doublet and three right-handed Majorana fermions as an iso-singlet. A real/complex scalar field is added as a dark matter candidate. We impose a global $U(1)_ μ$ symmetry under which fields associated with the SM muon are charged. To stabilize the dark matter, we impose a $Z_2$ (or $Z_3$) symmetry under which the exotic lepton doublet and the real (or complex) scalar field are charged. We find that the model can simultaneously ex…
Several experiments revealed intriguing hints for lepton flavor universality (LFU) violating new physics (NP) in semi-leptonic $B$ meson decays, mainly in $b \to c τν$ and $b \to s \ell^+ \ell^-$ transitions at the $3-5\,σ$ level. Leptoquarks (LQ) are prime candidates to address these anomalies as they contribute to semi-leptonic decays already at tree level while effects in other flavor observables, agreeing with the standard model (SM), are loop suppressed. In these proceedings we review the vector leptoquark $SU(2)_L$ singlet, contained in the famous Pati-Salam model, which is able to addre…
A new heavy $Z'$ vector boson provides a possible explanation for the neutral current B anomalies and points to the scale where we expect the solution to the hierarchy problem to appear. In this paper, we explore a modified Top Seesaw model based on the global symmetry breaking of $U(3)_L$ to $U(2)_L$. The symmetry is partially gauged such that the breaking introduces not only a composite Higgs doublet but also a TeV-scale $Z'$ boson. The $U(3)_L/U(2)_L$ Top Seesaw model predicts a light Higgs boson as well as a large top Yukawa coupling. Additional $U(1)'$ symmetry is gauged such that a flavo…
The recent experimental results including $R_{K^{(\ast)}}$, $R_{D^{(\ast)}}$, $(g-2)_μ$ and $W$ mass show deviations from the standard model (SM) predictions, implying the clues of new physics (NP). In this work, we investigate the explanations of these anomalies in the $R$-parity violating minimal supersymmetric standard model (RPV-MSSM) extended with the inverse seesaw mechanism. The non-unitarity extent $η_{ee}$ and the loop corrections from the interaction $λ'\hat L \hat Q \hat D$ are utilized to raise the prediction of $W$ mass through muon decays. We also find that the interaction $λ'\ha…
We discuss a simple renormalisable, gauge invariant model with a fermiophobic $Z'$ boson: it has no couplings to the three Standard Model (SM) chiral families, but does couple to a fourth vector-like (VL) family. The SM Higgs couples to the fourth VL lepton, leading to an enhanced contribution to the muon anomalous magnetic moment $\left(g-2\right)_μ$. The latter contribution requires a non-vanishing coupling of $Z'$ to right-handed muons, which arises within this model due to mixing effects between the SM and VL fermions, along with $Z'$ couplings to the second generation SM lepton doublet an…
A new heavy $Z'$ vector boson provides a possible explanation for the neutral current B anomalies. Various $U(1)'$ gauge groups have been proposed and studied. In this paper, we explore a new type of $U(1)'$ gauge symmetry inspired by fundamental composite Higgs models with hyperfermions. It is also the first attempt to connect such a $Z'$ boson with a solution to the hierarchy problem. The $U(1)'$ symmetry is identified as the quantum number of the difference between the Standard Model fermion number and hyperbaryon number, written as $SM-HB$. This type of $U(1)'$ gauge symmetry is naturally …
We investigate the iso-doublet vector leptoquark $V_2$ as a solution to the $B$ anomalies $R_{K, K^*}$ and $R_{D,D^*}$, as well as explaining the muon and electron anomalous magnetic moments, and the very recent $W$-mass anomaly.
The LHC observed deviations from the Standard Model (SM) in the flavour sector: LHCb found a $4.3\,σ$ discrepancy compared to the SM in $b\to sμμ$ transitions and CMS reported a non-zero measurement of $h\toμτ$ with a significance of $2.4\,σ$. Here we discuss how these deviations from the SM can be explained, focusing on two models with gauged $L_μ-L_τ$ symmetry. The first model contains two scalar doublets and vector-like quarks while the second one employs three scalar doublets but does not require vector-like fermions. In both models, interesting correlations between $b\to sμμ$ transitions,…
The SUSY contributions $Δa_μ$ to muon $g-2$ anomaly can not even reach $3σ$ in ordinary gauge mediated SUSY breaking (GMSB) scenarios because of the strong correlations between the colored sparticle masses and the uncolored EW sparticle masses. An interesting extension to GMSB is the (Extra)Ordinary Gauge Mediation (EOGM), which can relax the correlations between squarks and sleptons with non-universal choices for $N_{eff,3}$ and $N_{eff,2}$. We find that EOGM scenarios with $N_{eff,3}\ll N_{eff,2}$ can explain the muon $g-2$ anomaly within $3σ$ range, however can not explain the new W-boson m…
Motivated by the recent anomalies in $b\rightarrow s$ transitions that emerged at LHCb, we consider a model with an $L_μ- L_τ$ gauge symmetry and additional vector-like fermions. We find that by introducing supersymmetry the model can be made consistent with the long-standing deviation in the measured value of the anomalous magnetic moment of the muon, $g-2$, and neutralino dark matter of broad mass ranges and properties. In particular, dark matter candidates include the well-known 1 TeV higgsino, which in the MSSM is typically not compatible with solutions to the $g-2$ puzzle. Moreover, its s…
The FNAL+BNL measurements for muon $g-2$ is $4.2σ$ above the SM prediction, and the Berkeley $^{133}$Cs measurement for the fine-structure constant $α_{\rm em}$ leads to the SM prediction for electron $g-2$ which is $2.4σ$ above the experimental value. Hence, a joint explanation of both anomalies requires a positive contribution to muon $g-2$ and a negative contribution to electron $g-2$, which is rather challenging. In this work we explore the possibility of such a joint explanation in the minimal supersymmetric standard model (MSSM). Assuming no universality between smuon and selectron soft …
We explain anomalies currently present in various data samples used for the measurement of the anomalous magnetic moment of electron ($a_e$) and muon ($a_μ$) in terms of an Aligned 2-Higgs Doublet Model with right-handed neutrinos. The explanation is driven by one and two-loop topologies wherein a very light CP-odd neutral Higgs state ($A$) contributes significantly to $a_μ$ but negligibly to $a_e$, so as to revert the sign of the new physics corrections in the former case with respect to the latter, wherein the dominant contribution is due to a charged Higgs boson ($H^\pm$) and heavy neutrino…
Explaining 650 GeV and 95 GeV Anomalies in the 2-Higgs Doublet Model Type-I
在2HDM-I中，通过gg产生的CP-odd Higgs A（~650 GeV）衰变为SM-like Higgs H（→γγ）和Z（→bb），并引入~95 GeV的轻CP-even Higgs h，同时解释LHC和LEP的多个异常，显著性达2.5σ。
We propose an extension of the standard model (SM) with $U(1)_{μ-τ}$ gauge symmetry, extra vectorlike quark doublets $Q'_a$ and singlet scalar $χ$, both of which are charged under $U(1)_{μ-τ}$ and carry {odd} dark $Z_2$ parity. Then assuming that $χ$ is the dark matter (DM) of the universe and imposing various constraints from dark matter search, flavor physics and collider search for $Q'_a$, one can show that radiative corrections to $b\rightarrow s Z^{'*} \rightarrow s l^+ l^- $ involving $Q'_a$ and $χ$ can induce $ΔC_9 \sim -1$ which can resolve the LHCb anomalies related with $B\to K^{(*)}…
We present a dark sector model based on gauging the $L_μ- L_τ$ symmetry that addresses anomalies in $b \rightarrow s μ^+ μ^-$ decays and that features a particle dark matter candidate. The dark matter particle candidate is a vector-like Dirac fermion coupled to the $Z^\prime$ gauge boson of the $L_μ-L_τ$ symmetry. We compute the dark matter thermal relic density, its pair-annihilation cross section, and the loop-suppressed dark matter-nucleon scattering cross section, and compare our predictions with current and future experimental results. We demonstrate that after taking into account bounds …
Motivated by the recent anomalies in $b \to s \ell^+ \ell^-$ transitions, we explore a minimal $Z^\prime$ scenario, in which the $Z^\prime$ boson has a flavour-changing coupling to charm and top quarks and a flavour-conserving coupling to muons. It is found that such a $Z^\prime$ boson can explain the current $b \to s \ell^+ \ell^-$ anomalies, while satisfying other flavour and collider constraints simultaneously. The $Z^\prime$ boson can be as light as few hundreds GeV. In this case, the $t \to c μ^+ μ^-$ decay and the $tZ^\prime$ associated production at the LHC could provide sensitive probe…
We investigate the predictions for various nucleon decay rates and their ratios in non-supersymmetric SU(5) Grand Unified Theories (GUTs) where the masses of the third and second family down-type quarks and charged leptons each stem dominantly from single GUT operators. Extending the Georgi-Glashow SU(5) model by a 45-dimensional GUT-Higgs representation, the gauge couplings can meet at the high scale $M_\mathrm{GUT}$ and the GUT scale predictions $y_τ/y_b = 3/2$ and $y_μ/y_s = 9/2$ can emerge within single operator dominance. Explaining the observed neutrino masses via the type I seesaw mecha…
We study the possibility of explaining the recently found anomalies in B-meson decays within scenarios with a composite Higgs boson. This class of models provides a natural way to fit the experimental results, interpreting the anomalies as the result of the exchange of heavy vector resonances with electroweak quantum numbers. The anomalies are tightly related to deviations in Delta F = 2 transitions and to deformations of the Z and W couplings, whose size is of the order of the present experimental bounds. This leads to a very predictive scenario which could be soon tested at collider experime…
Explaining Data Anomalies over the NMSSM Parameter Space with Deep Learning Techniques
本文利用深度学习辅助的高效数值扫描策略，在NMSSM参数空间中寻找能同时容纳95GeV与650GeV希格斯超出、Electro-Weakino超出、$(g-2)_μ$偏差及暗物质单-$H$/$Z$特征等数据异常的可行区域，并给出若干基准点。
Explaining ATOMKI, $(g-2)_μ$, and MiniBooNE anomalies with light mediators in $U(1)_H$ extended model
本文提出Type-I 2HDM的$U(1)_H$扩展模型，通过引入质量约17 MeV的轻矢量玻色子和10-100 MeV的轻标量粒子，同时解释了ATOMKI铍异常、带电轻子反常磁矩和MiniBooNE事件过量。
It is suggested that the Higgs boson may have a branching ratio into the $c \bar{c}$ mode suppressed by several orders of magnitude compared with conventional predictions and in addition some small but detectable flavour-violating modes such as $b \bar{s}$ and $τ\barμ$. The suggestion is based on a scheme proposed and tested earlier for explaining the mixing pattern and mass hierarchy of fermions in terms of a rotating mass matrix. If confirmed, the effects would cast new light on the geometric origin of fermion generations and of the Higgs field itself.
Recent LHCb results on $R_{K^*}$, the ratio of the branching fractions of $B \to K^* μ^+ μ^-$ to that of $B \to K^* e^+ e^-$, for the dilepton invariant mass bins $q^2 \equiv m_{\ell\ell}^2 = [0.045 - 1.1]$ GeV$^2$ and $[1.1 - 6]$ GeV$^2$ show approximately $2.5 σ$ deviations from the corresponding Standard Model prediction in each of the bins. This, when combined with the measurement of $R_K \, (q^2=[1-6]\, \rm GeV^2)$, a similar ratio for the decay to a pseudo scalar meson, highly suggests for lepton non-universal new physics in semi-leptonic $B$ meson decays. In this work, we perform a mode…
Recently Arkani-Hamed, Finkbeiner, Slatyer and Weiner proposed a unified explanation to the set of experimental and observational anomalies with possible connections to Dark Matter (DM). A central role is played by GeV scale "dark" gauge bosons exchanged by the weak scale DM. Motivated by this proposal, we build an explicit model of DM in the context of Weak Scale Supersymmetry (SUSY). We employ high-scale SUSY-breaking and invoke the Giudice-Masiero mechanism to generate the weak scale DM masses. By sequestering the dark sector from the SUSY-breaking "hidden" sector, it naturally acquires GeV…
Electroweak baryogenesis from charged current anomalies in $B$ meson decays
首次证明解释带电$B$介子反常$R(D^{(*)})$的新物理可作为CP破坏源以解释宇宙重子不对称性，在一般双Higgs二重态模型中计算BAU并指出其可被未来实验探测。
A possibility of explaining the anomalies in the semileptonic $B$-meson decay $B \to K^{*} μ\barμ$ has been explored in the framework of the gauged $U(1)_{μ-τ}$ symmetry. Apart from the muon anomalous magnetic moment and neutrino sector, we formulate the model starting with a valid Lagrangian and consider the constraints from the neutral meson mixings, the bounds on direct detection and the relic density of the bosonic dark matter candidate augmented to collider constraints. We search the parameter space, which accommodates the size of the anomaly of the $B \rightarrow K^* μ\bar μ$ decay, to s…
The basic principle of naturalness has driven the majority of the LHC program, but so far all searches for new physics beyond the SM have come up empty. On the other hand, existing measurements of SM processes contain interesting anomalies, which allow for the possibility of new physics with mass scales very close to the Electroweak Scale. In this paper we show that SUSY could have stops with masses ~ O(200) GeV based on an anomaly in the WW cross section, measured by both ATLAS and CMS at 7 and 8 TeV. In particular we show that there are several different classes of stop driven scenarios that…
Explaining the $B_{d,s}\rightarrow {K^{(*)}\bar K^{(*)}}$ non-leptonic puzzle and charged-current $B$-anomalies via scalar leptoquarks
本文提出基于 $S_1$ 标量轻子夸克和 $U(2)$ 味对称性的模型，通过一圈色磁偶极贡献同时解释非轻子 $B$ 衰变张力与带电流轻子味普适性破坏，并预言 $B\rightarrow K ν\bar ν$ 分支比接近现有界限。
The experimental measurements on flavour physics, in tension with Standard Model predictions, exhibit large sources of Lepton Flavour Universality violation. We perform an analysis of the effects of the global fits on the Wilson coefficients assuming a model independent effective Hamiltonian approach, by including a set of different scenarios in which the New Physics contributions to the Wilson coefficients are present in one, two or three of the Wilson coefficients at a time. We compare the results of the global fit with respect to two cases: the Standard Model and the more general case in wh…
In a (0,1) supersymmetric (SUSY) six-dimensional gauge theory, a gauge fermion gives rise to box anomalies. These anomalies are completely canceled by assuming a vector multiplet of (1,1) SUSY. With a T^2/Z_3 orbifold compactification of the extra two dimensional space, the theory provides three chiral multiplets and three equivalent fixed points. We regard them as the origin of the three families of quarks and leptons. Quasi anarchy structure in the SU(5)-5^* representation sector and hence the bimaximal mixing in the neutrino oscillation are explained quite naturally in this framework. We al…
We propose a possible explanation of the recent diphoton excess reported by ATLAS and CMS collaborations, at around 750 GeV diphoton invariant mass, within the framework of $E_{6}$ motivated Alternative Left-Right Symmetric Model (ALRSM), which is capable of addressing the $B$ decay anomalies in the flavor sector, the $eejj$ and $e$ missing $p_{T}jj$ excesses reported by CMS in run 1 of LHC and has the feature of high scale leptogenesis. We find that gluon-gluon fusion can give the observed production rate of the 750 GeV resonance, $\tilde{n}$, through a loop of scalar leptoquarks ($\tilde{h}^…
The Low-Scale Seesaw Solution to the $M_W$ and $(g-2)_μ$ Anomalies
针对CDF-II的$W$质量与缪子$g-2$异常，提出低尺度跷跷板机制下的简化标准模型扩展，引入一对矢量轻子，联合解释两种异常，并讨论三族推广。
Flavor specific chiral $U(1)_X$ framework for explaining the ATOMKI anomaly
本文提出一种基于Chiral U(1)_X扩展的标准模型，通过双Higgs双态框架生成非零轴向耦合，解释ATOMKI异常并满足实验约束。
Scenarios in which right-handed light Standard Model fermions couple to a new gauge group, $U(1)_{T3R}$ can naturally generate a sub-GeV dark matter candidate. But such models necessarily have large couplings to the Standard Model, generally yielding tight experimental constraints. We show that the contributions to $g_μ-2$ from the dark photon and dark Higgs largely cancel out in the narrow window where all the experimental constraints are satisfied, leaving a net correction which is consistent with recent measurements from Fermilab. These models inherently violate lepton universality, and UV …
We construct an unified model of inflation and PeV dark matter with an appropriate choice of no-scale Kähler potential, superpotential and gauge kinetic function in terms of MSSM fields and hidden sector Polonyi field. The model is consistent with the CMB observations and can explain the PeV neutrino flux observed at IceCube HESE. A Starobinsky like Higgs-sneutrino plateau inflation is obtained from the $D$-term SUGRA potential while $F$-term being subdominant during inflation. To get PeV dark matter, SUSY breaking at PeV scale is achieved through Polonyi field. This sets the scale for soft SU…
In this work we extend the SM by introducing only exotic scalars and leptons and show that within the reasonable error limits, both the observed anomalies in $R(D^{(*)})$ and $R_{K^{(*)}}$ can be explained along with satisfying all the constrains from nuetral meson oscillations, precision Z-pole data etc. In a trivial extension of our model with addition of three heavy right handed neutrinos, explaining the small masses of neutrinos and generation of Baryon excess via leptogenesis is possible as well. The disagreement between SM prediction and experimental data in muon (g-2) measurements can b…
A recent CMS search for the right handed gauge boson $W_R$ reports an interesting deviation from the Standard Model. The search has been conducted in the $eejj$ channel and has shown a 2.8$σ$ excess around $m_{eejj} \sim 2$ TeV. In this work, we explain the reported CMS excess with R-parity violating supersymmetry (SUSY). We consider resonant selectron and sneutrino production, followed by the three body decays of the neutralino and chargino via an $\mathcal{R}-$parity violating coupling. We fit the excess for slepton masses around 2 TeV. The scenario can further be tested in neutrinoless doub…
We introduce two scalar leptoquarks, the SU$(2)_L$ isosinglet denoted $ϕ\sim(\mathbf{3}, \mathbf{1}, -1/3)$ and the isotriplet $φ\sim(\mathbf{3}, \mathbf{3}, -1/3)$, to explain observed deviations from the standard model in semi-leptonic $B$-meson decays. We explore the regions of parameter space in which this model accommodates the persistent tensions in the decay observables $R_{D^{(*)}}$, $R_{K^{(*)}}$, and angular observables in $b\to s μμ$ transitions. Additionally, we exploit the role of these exotics in existing models for one-loop neutrino mass generation derived from $ΔL=2$ effective …
Searches for supersymmetric particles with prompt decays with the ATLAS detector
本文报告了ATLAS实验在CERN LHC上开展的电弱和强超对称性搜索最新结果，涵盖多种末态及R宇称守恒与破坏模型，并强调了机器学习等新型分析技术在提升探测灵敏度中的关键作用。
We investigate models of a heavy neutral gauge boson Z' which could explain anomalies in B meson decays reported by the LHCb experiment. In these models, the Z' boson couples mostly to third generation fermions. We show that bottom quarks arising from gluon splitting can fuse into Z' as an essential production mechanism at the LHC, thereby allowing to probe these models. The study is performed within a generic framework for explaining the B anomalies that can be accommodated in well motivated models. The flavor violating b s coupling associated with Z' in such models produces lower bound on th…
In the past few years, several hints of lepton flavour universality (LFU) violation have emerged in the $b \to c τ\barν$ and $b \to s \ell^+ \ell^-$ data. Quite recently, the Belle Collaboration has reported the first measurement of the $D^*$ longitudinal polarization fraction in the $B \to D^* τ\barν$ decay. Motivated by this intriguing result, together with the recent measurements of $R_{J/ψ}$ and $τ$ polarization, we study $b \to c τ\barν$ decays in the Supersymmetry (SUSY) with $R$-parity violation (RPV). We consider $B \to D^{(*)} τ\barν$, $B_c \to η_c τ\barν$, $B_c \to J/ψτ\barν$ and $Λ_…
The singly charged $SU(2)_L$ singlet scalar, with its necessarily flavour violating couplings to leptons, lends itself particularly well for an explanation of the Cabibbo Angle Anomaly and of hints for lepton flavour universality violation in $τ\to μ\bar νν$. In a setup addressing both anomalies, we predict loop-induced effects in $τ\to eγ$ and in $τ\to eμμ$. A recast of ATLAS selectron and smuon searches allows us to derive a coupling-independent lower limit of $\approx 200$ GeV on the mass of the singly charged singlet scalar. At a future $e^+e^-$ collider, dark matter mono-photon searches c…
We consider the most general generation-independent U(1) gauge symmetry consistent with the presence of Yukawa couplings for all quarks and leptons in the SUSY version of the Standard Model. This U(1) has generically mixed anomalies with SM groups, which cannot be cancelled by the Green-Schwarz mechanism of heterotic D=4 strings. We argue that these anomalies can in principle be cancelled by the generalized Green-Schwarz mechanism present in field theories corresponding to D-branes at singularities. Moreover, unlike the heterotic case, once the U(1) symmetry is broken it may remain as an exact…
The most statistically significant hints for new physics in the flavor sector are discrepancies between theory and experiment in $B$ decays to lepton pairs ($b\to s\ell^+\ell^-$) and a deficit in $1^{\rm st}$ row CKM unitarity (the Cabibbo Angle anomaly). We propose that these anomalies can be reconciled by a simplified model with massive gauge bosons transforming in the adjoint representation of $SU(2)_L$. After calculating the impact of this model on $B$ decays, observables testing charged current lepton flavor universality (LFU), electro-weak precision observables and LHC searches we perfor…
We consider the extension of the Standard Model with scalar leptoquarks as a portal to dark matter (DM), motivated by the recent anomalies in semi-leptonic $B$-meson decays. Taking singlet and triplet scalar leptoquarks as the best scenarios for explaining $B$-meson anomalies, we discuss the phenomenological constraints from rare meson decays, muon $(g-2)_μ$, and leptoquark searches at the Large Hadron Collider (LHC). Introducing leptoquark couplings to scalar dark matter, we find that the DM annihilations into a pair of leptoquarks open a wide parameter space, being compatible with XENON1T bo…
We analyze the possibility to accommodate current $b \to s \ell^+ \ell^-$ anomalies with TeV-scale mediators that couple to right-handed top quarks and muons, contributing to $b \to s \ell^+ \ell^-\,$ at the one-loop level. We use the Standard Model Effective Field Theory (SMEFT) framework but also look at specific scenarios by taking into account all possible irreducible representations of the Lorentz and Standard Model gauge group for the mediators. From a global fit of $b \to s \ell^+ \ell^-$ data and LEP-I observables we find that the Wilson coefficients of two SMEFT operators: $\mathcal{O…
The LHC observed so far three deviations from the Standard Model (SM) predictions in flavour observables: LHCb reported anomalies in $B\to K^* μ^+μ^-$ and $R(K)=B\to K μ^+μ^-/B\to K e^+e^-$ while CMS found an excess in $h\toμτ$. We show, for the first time, how these deviations from the SM can be explained within a single well-motivated model: a two-Higgs-doublet model with gauged $L_μ-L_τ$ symmetry. We find that, despite the constraints from $τ\toμμμ$ and $B_s$--$\overline{B}_s$ mixing, one can explain $h \toμτ$, $B\to K^* μ^+μ^-$ and $R(K)$ simultaneously, obtaining interesting correlations …
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