D∗D^{\ast} polarization vs. RD(∗)R_{D^{(\ast)}} anomalies in the leptoquark models

Polarization measurements in $\bar{B} \to D^{(\ast)} \tau \overline{\nu}$ are useful to check consistency in new physics explanations for the $R_{D}$ and $R_{D^{\ast}}$ anomalies. In this paper, we investigate the $D^{\ast}$ and $\tau$ polarizations and focus on the new physics contributions to the fraction of a longitudinal $D^{\ast}$ polarization ($F_{L}^{D^{\ast}}$), which is recently measured by the Belle collaboration $F_{L}^{D^{\ast}} = 0.60 \pm 0.09$, in model-independent manner and in each single leptoquark model (${\rm R}_2$, ${\rm S}_1$ and ${\rm U}_1$) that can naturally explain the $R_{D^{(\ast)}}$ anomalies. It is found that $\mathcal{B}(B_c^{+} \to \tau^{+} \nu)$ severely restricts deviation from the Standard Model (SM) prediction of $F_{L, \textrm{SM}}^{D^{\ast}} = 0.46 \pm 0.04$ in the leptoquark models: [0.43, 0.44], [0.42, 0.48], and [0.43, 0.47] are predicted as a range of $F_{L}^{D^{\ast}}$ for the ${\rm R}_2$, ${\rm S}_1$, and ${\rm U}_1$ leptoquark models, respectively, where the current data of $R_{D^{(\ast)}}$ is satisfied at $1\,\sigma$ level. It is also shown that the $\tau$ polarization observables can much deviate from the SM predictions. The Belle II experiment, therefore, can check such correlations between $R_{D^{(\ast)}}$ and the polarization observables, and discriminate among the leptoquark models.Comment: 24 pages, 3 figures, 1 table; references added, version published in JHE

Global fit to b→cτνb \to c\tau\nu anomalies 2022 mid-autumn

Recently, the LHCb collaboration announced a preliminary result of the test of lepton flavor universality (LFU) in $B\to D^{(\ast)}$ semi-leptonic decays: $R_{D}^{\rm LHCb2022} = 0.441 \pm 0.089$ and $R_{D^{\ast}}^{\rm LHCb2022} = 0.281 \pm 0.030$ based on the LHC Run 1 data. This is the first result of $R_{D}$ for the LHCb experiment, and its precision is comparable to the other $B$-factory data. Interestingly, those data prefer the violation of the LFU again. A new world average of the data from the BaBar, Belle, and LHCb collaborations is $R_{D} = 0.358 \pm 0.027$ and $R_{D^{\ast}} = 0.285 \pm 0.013$. Including this new data, we update a circumstance of the $b \to c \tau \overline\nu$ measurements and their implications for new physics. Incorporating recent developments for the $B \to D^{(\ast)}$ form factors in the Standard Model (SM), we observe a $4.1 \sigma$ deviation from the SM predictions. Our updates also include; model-independent new physics (NP) formulae for the related observables; and the global fittings of parameters for leptoquark scenarios as well as single NP operator scenarios. Furthermore, we show future potential to indirectly distinguish different new physics scenarios with the use of the precise measurements of the polarization observables in $B\to D^{(\ast)}\tau \overline\nu$ at the Belle II and the high-$p_{\rm T}$ flavored-tail searches at the LHC. We also discuss an impact on the LFU violation in $\Upsilon \to l^+ l^-$.Comment: 38 pages, 5 figures, 6 Tables; v2: references adde

Non-resonant new physics search at the LHC for the b → cτν anomalies

Motivated by the →$\overline{}$ anomalies, we study non-resonant searches for new physics at the large hadron collider (LHC) by considering final states with an energetic and hadronically decaying τ lepton, a b-jet and large missing transverse momentum (→ℎ$\overline{}$+$^{miss}$$_{T}$). Such searches can be useful to probe new physics contributions to →$\overline{}$. They are analyzed not only within the dimension-six effective field theory (EFT) but also in explicit leptoquark (LQ) models with the LQ non-decoupled. The former is realized by taking a limit of large LQ mass in the latter. It is clarified that the LHC sensitivity is sensitive to the LQ mass for (1) TeV even in the search of →ℎ$\overline{}$+$^{miss}$$_{T}$. Although the LQ models provide a weaker sensitivity than the EFT limit, it is found that the non-resonant search of →ℎ$\overline{}$+$^{miss}$$_{T}$ can improve the sensitivity by ≈ 40% versus a conventional mono-τ search (→ℎ$\overline{}$+$^{miss}$$_{T}$) in the whole LQ mass region. Consequently, it is expected that most of the parameter regions suggested by the →$\overline{}$⎯ anomalies can be probed at the HL-LHC. Also, it is shown that R$_{2}$ LQ scenario is accessible entirely once the LHC Run 2 data are analyzed. In addition, we discuss a charge selection of τh to further suppress the standard-model background, and investigate the angular correlations among b, τ and the missing transverse momentum to discriminate the LQ scenarios

Clinical application of a 3-dimensional morphometric apparatus for diagnosis and treatment of a Class III patient with facial asymmetry : A pilot study

This article demonstrated the usefulness of a non-contact 3-dimensional (3D) morphometric apparatus in orthodontic diagnosis and treatment evaluation. A female patient, 23 years 6 months of age, had a Class III malocclusion with mandibular deviation. The 3D images taken by a 3D morphometric apparatus figured out her protrusive chin of 6 mm on the deviation side compared to the non-deviation side, and showed a possibility of orthognathic surgery. Before starting of orthodontic treatment, a diagnostic splint was used for 2 months to determine her proper mandibular position. The 3D images retaken for quantitative evaluation showed decrease of the mandibular protrusion by approximately 3 mm, and improvement of facial asymmetry. Then, we decided to treat the patient without orthognathic surgery. After 18 months of active orthodontic treatment with miniscrew anchorage, the mandibular deviation was improved and an acceptable occlusion was achieved. The 3D images at posttreatment demonstrated significant decrease of chin protrusion on the deviation side, and improvement of facial asymmetry. In conclusion, a 3D morphometric apparatus could provide quantitative data of facial asymmetry and chin protrusion and contributed decision making process of treatment planning in a patient with facial asymmetry

Berry curvature induced valley Hall effect in non-encapsulated hBN/Bilayer graphene heterostructure aligned with near-zero twist angle

Valley Hall effect has been observed in asymmetric single-layer and bilayer graphene systems. In single-layer graphene systems, asymmetry is introduced by aligning graphene with hexagonal boron nitride (hBN) with a near-zero twist angle, breaking the sub-lattice symmetry. Although a similar approach has been used in bilayer graphene to break the layer symmetry and thereby observe the valley Hall effect, the bilayer graphene was sandwiched with hBN on both sides in those studies. This study looks at a much simpler, non-encapsulated structure where hBN is present only at the top of graphene. The crystallographic axes of both hBN and bilayer graphene are aligned. A clear signature of the valley Hall effect through non-local resistance measurement ($R_{\rm{NL}}$) was observed. The observed non-local resistance could be manipulated by applying a displacement field across the heterostructure. Furthermore, the electronic band structure and Berry curvature calculations validate the experimental observations

Impact of Λb→Λcτν measurement on new physics in b→clν transitions

Measurements of the branching ratios of B→D(*)τ¯ν/B→D(*)ℓ¯ν and Bc→J/ψτ¯ν/Bc→J/ψℓ¯ν by the BABAR, Belle and LHCb collaborations consistently point towards an abundance of taus compared to channels with light leptons. However, the ratio Λb→Λcτ¯ν/Λb→Λcℓ¯ν shows a relative deficit in taus. In this paper, we critically address whether data still points towards a coherent pattern of deviations, in particular in light of the sum rule relating these decays in a model-independent way. We find that no common new physics explanation of all ratios is possible (within 2σ or 1.5σ, depending on the R(Λc) normalization to light lepton channels). While this inconsistency could be a statistical fluctuation, further measurements are required in order to converge to a coherent pattern of experimental results

Impact of Λb→Λcτν\Lambda_b\to \Lambda_c\tau\nu measurement on New Physics in b→c lνb\to c \, l \nu transitions

Measurements of the branching ratios of $B \to D^{(*)}\tau\bar\nu/B \to D^{(*)}\ell\bar\nu$ and $B_c\to J/\psi\, \tau\bar\nu/B_c\to J/\psi\, \ell\bar\nu$ by the BaBar, Belle and LHCb collaborations consistently point towards an abundance of taus compared to channels with light leptons. However, the ratio $\Lambda_b \to\Lambda_c \tau\bar\nu/\Lambda_b \to\Lambda_c \ell\bar\nu$ shows a relative deficit in taus. In this paper, we critically address whether data still points towards a coherent pattern of deviations, in particular in light of the sum rule relating these decays in a model-independent way. We find that no common new physics explanation of all ratios is possible (within $2\sigma$ or $1.5\sigma$, depending on the ${\cal R}(\Lambda_c)$ normalization to light lepton channels). While this inconsistency could be a statistical fluctuation, further measurements are required in order to converge to a coherent pattern of experimental results.Comment: 12 pages, 3 table