DOI： 10.1088/1361-6471/ae05b4

Open Access

Web of Science

出版者・発行元：European Physical Journal C  

In the originally published version of this article, Table 1 contained incorrect values in the column labeled “Value”. Specifically: Value 1 was incorrectly listed as 0.182 and has been corrected to 0.18. Value 5 was incorrectly listed as 0.02 ± 0.183i and has been corrected to 0.18. The original article has been revised. The publisher apologizes for any inconvenience caused.

DOI： 10.1140/epjc/s10052-025-14757-y

Open Access

Web of Science

Scopus

掲載種別：研究論文（学術雑誌）   出版者・発行元：European Physical Journal C  

Lepton flavor universality is a key prediction of the Standard Model of particle physics, and any violation of it immediately indicates the existence of new physics. Given the recent discrepancy of more than 4σ in charged current semileptonic B meson decays and the absence of evident signals at the Large Hadron Collider, independent cross-checks become invaluable. In this context, b→c semileptonic sum rules based on heavy quark symmetry are interesting, since they allow us to check the consistency of experimental results. In this paper, we report newly found sum rules among angular observables of mesonic and baryonic b→clν¯ decays holding exactly in the large mass limit of heavy quarks. Moreover, we investigate corrections to the sum rule in realistic situations and discuss phenomenological implications.

DOI： 10.1140/epjc/s10052-025-14598-9

Open Access

Web of Science

Scopus

arXiv

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その他リンク： http://arxiv.org/pdf/2506.16027v1

掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Cosmology and Astroparticle Physics  

We present a novel mechanism for the irreducible production of magnetic monopoles from interactions of cosmic rays and interstellar medium (ISM). Resulting monopoles drain energy from galactic magnetic fields, disrupting their formation and sustainability. We generalize conventional Parker bounds to monopoles with extended energy spectrum and, considering cosmic ray ISM monopole production, set novel constraints from disruption of Milky Way Galactic magnetic fields and their seeds. Further, we set first constraints on disruption of galactic magnetic fields and their seeds of Andromeda galaxy, with results being competitive with distinct existing bounds. Unlike Parker limits of previous works that relied on cosmological monopoles, our constraints are independent of cosmological monopole production or their primordial abundance. Besides, we estimate new constraints on dipole magnetic moments generated from cosmic ray ISM interactions. We discuss implications for monopoles with generalized magnetic charges.

DOI： 10.1088/1475-7516/2025/08/022

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Web of Science

Scopus

arXiv

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その他リンク： http://arxiv.org/pdf/2412.15132v1

掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of High Energy Physics  

The semi-leptonic b → clν processes are receiving a lot of attention, as the lepton flavor universality (LFU) violation has been hinted by the measured ratios RD∗ = Γ(B → D^(∗)τν)/Γ(B → D^(∗)ℓν) for ℓ = e, μ. Recently, it has also been pointed out that the baryonic counterpart, RΛc = Γ(Λ<inf>b</inf> → Λ<inf>c</inf>τν)/Γ(Λ<inf>b</inf> → Λ<inf>c</inf>ℓν), has a strong correlation with RD∗, referred to as the R ratio sum rule in this paper. The correlation is almost independent of the new physics (NP) implication and hence can predict RΛc from the measured RD∗. On the other hand, we have fewer measurements and/or theoretical studies of the semi-leptonic b → ulν processes, although the same arguments can be applied to the ratios R<inf>π</inf>, R<inf>ρ</inf>, and R<inf>p</inf> as above. Since these processes are measurable at the ongoing LHCb run-3 and/or Belle II experiments, precise studies on them are important as well. In this paper, we obtain the semi-analytic formulae for all the aforementioned R<inf>X</inf> ratios in the presence of NP contributions by using the available lattice QCD and/or light-cone sum rule fits to the form factors. Two novel points are highlighted: (i) We evaluate uncertainties of R<inf>X</inf> including both the Standard Model (SM) and NP terms, inherited from the form factor fits, and discuss how the uncertainties affect the R ratio sum rules. (ii) We obtain the R ratio sum rule among the semi-leptonic b → ulν processes for the first time, which provides a complementary motivation for observing these processes. In addition, based on our numerical results, we investigate how the different NP scenarios work in the b → c and b → u sectors and perform a combined study in the framework of SM effective field theory with specific flavor symmetries.

DOI： 10.1007/JHEP07(2025)166

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arXiv

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出版者・発行元：Journal of High Energy Physics  

Lepton flavor universality violations in semileptonic b → c transitions have garnered attention over a decade. For with ℓ being e, μ, a sum rule among R<inf>D</inf>, and R<inf>Λc</inf> was proposed to check consistency in the experimental results independently of new physics models. We revisit this relation from the perspective of the heavy quark symmetry. We derive a sum rule holding exactly in the heavy quark limit and clarify how model-dependent corrections are introduced in a realistic situation.

DOI： 10.1007/JHEP05(2025)112

Open Access

Web of Science

Scopus

出版者・発行元：Proceedings of Science  

We perform a global fit to the two Higgs doublet model (2HDM) with generic sources of flavour violation using GAMBIT. This is particularly interesting in light of significant deviations from the Standard Model predictions, such as the flavour anomalies R(D^(∗)) and b → sℓ⁺ℓ^- and the indications for a charged Higgs with a mass of 130 GeV in top quark decays at ATLAS. We include all relevant constraints from precision, flavour and collider observables in the global fit, and in particular recent constraints from both quark flavour violating searches at ATLAS and CMS, and lepton flavour violation from Belle II. We also consider the impact of recent developments related to the W mass and muon g - 2 observables. We find that it is possible to simultaneously explain both the charged and neutral flavour anomalies when excluding the values obtained by the CDF-II detector for the m<inf>W</inf> mass and when using the BMW lattice results for muon g - 2. In contrast if we either assume there is still a large deviation in muon g - 2 requiring new physics, or that the CDF-II measurement of the W mass is correct, we find that a simultaneous explanation of all the anomalies is no longer possible. Finally we provide predictions that can probe or rule out the model in lepton flavour violating searches at Belle II and also in Higgs coupling strength measurements at the future HL-LHC.

Scopus

記述言語：日本語   出版者・発行元：一般社団法人 日本物理学会  

<p>素粒子の標準模型は欧州原子核研究機構（CERN）の大型ハドロンコライダー（LHC）における2012年のヒッグス粒子発見で予言されるすべての粒子が確認され確立された．対称性に基づき構成された標準模型には相互作用を媒介する4種類のスピン1粒子と12種類のスピン1/2の粒子（フェルミオン）が知られる．右図に示すように標準模型のフェルミオンの部分はアップ型クォーク，ダウン型クォーク，荷電レプトン，ニュートリノの4つの粒子の組み合わせ（このセットを世代と呼ぶ）の3つから構成され，繰り返しの3世代構造を持つ．標準模型は右図下部の光子などが媒介する相互作用では世代を区別しないことを予言する．一方でフェルミオンの質量を与えるヒッグス粒子との湯川相互作用は，特に質量の大きいトップクォークと軽いアップクォークでその強さが5桁異なるなど粒子の種類（フレーバーと呼ぶ）を明らかに区別する．これらの背後にある基本原理は何か？を標準模型を超える物理（NP）によって解決する模型も提唱されており，粒子のフレーバーに着目するフレーバー物理は標準模型の拡張を考える上で重要な手がかりを与えうる．</p><p>事実として2024年12月の時点では，地上での人類の高エネルギーフロンティアであるLHC実験からの新物理の証拠となる新粒子の発見の報告はない．一方でフレーバー物理では，2018年開始の高エネルギー加速器研究機構のBelle II実験やJ-PARC実験などの国内実験や欧州のLHCb実験など，先行実験の統計精度を遥かに上回る実験が近年進行中であり，現在標準模型の予言と精密な実験結果の間に4σ（標準偏差の4倍）ほどの食い違いが複数報告されている．フレーバー物理では精密測定を武器に，標準模型の検証および，標準模型の予言と精密な実験結果とを比較しその差異を手掛かりにNPの重い粒子を探索する．特に<i>B</i>中間子崩壊では，中性粒子やタウ粒子など測定が難しい粒子があるものの莫大な統計量を誇るLHCb実験と，低い重心エネルギーでの<i>e</i>^－<i>e</i>^＋衝突を用いて<i>B</i>中間子を生成し，より背景事象の少ない環境で崩壊を精査するBelle II実験が世界を牽引する．</p><p><i>B</i>中間子から<i>D</i>中間子やレプトンへのセミレプトニック崩壊では10年ほど前にアメリカのBaBar実験から標準模型の予言と実験値の間の食い違いが指摘されていたが，ここ3年で多くの独立実験結果が報告され，この結果は標準模型の綻びとこれを説明するTeVスケールの新物理の存在を示唆している可能性がある．この<i>B</i>中間子崩壊を正確に予言するには，ボトムクォークなどの素粒子レベルではなく<i>B</i>中間子から<i>D</i>や<i>K</i>などの軽い中間子へ遷移を，非摂動な量子色力学（QCD）の効果を含めて記述する必要がある．これに関し直近の2，3年で格子QCD計算の複数の独立グループが関連結果を公表しており，今後この理解が深まることが確実視されている．素粒子物理学における発見は，従来5σを基準として定義されているが，この差異の確定には進行中の実験での追検証とともに，上記の格子計算の進展も含む標準模型の予言の精密化が不可欠である．近年，食い違いが示唆する新物理模型の性質とLHCや核子の電気双極子モーメントなどにおけるこれらの新粒子の検証方法の研究も盛んに進み，多角的アプローチで当分野の発展が加速している．</p>

DOI： 10.11316/butsuri.80.4_166

Open Access

CiNii Research

The kaon physics programme, long heralded as a cutting-edge frontier by the
European Strategy for Particle Physics, continues to stand at the intersection
of discovery and innovation in high-energy physics (HEP). With its unparalleled
capacity to explore new physics at the multi-TeV scale, kaon research is poised
to unveil phenomena that could reshape our understanding of the Universe. This
document highlights the compelling physics case, with emphasis on exciting new
opportunities for advancing kaon physics not only in Europe but also on a
global stage. As an important player in the future of HEP, the kaon programme
promises to drive transformative breakthroughs, inviting exploration at the
forefront of scientific discovery.

DOI： 10.1088/1361-6471/ae05b4

Open Access

arXiv

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その他リンク： http://arxiv.org/pdf/2503.22256v1

掲載種別：研究論文（学術雑誌）   出版者・発行元：Physical Review D  

Charge-parity (CP) asymmetries in charm decays are extremely suppressed in the Standard Model and may well be dominated by new-physics contributions. The LHCb Collaboration reported the results of direct CP asymmetry measurements in D0→K+K- and D0→π+π- decays with unprecedented accuracy: aCP(K+K-)=(7.7±5.7)×10-4 and aCP(π+π-)=(23.2±6.1)×10-4, with the latter quantity inferred from the precise measurement of ΔaCP=aCP(K+K-)-aCP(π+π-)=(-15.7±2.9)×10-4. When interpreted within the Standard Model, these values indicate a breakdown of the approximate U-spin symmetry of QCD. If, however, this symmetry holds and the data stem from new physics, other CP asymmetries should be enhanced as well. We derive CP asymmetry sum rules based on SU(3) flavor symmetry for D meson decays into a pair of pseudoscalar mesons as well as a pair of a pseudoscalar and a vector meson for two generic scenarios, with ΔU=0 and |ΔU|=1 interactions, respectively. The correlations implied by the sum rules can be used to check the consistency between different measurements and to discriminate between these scenarios with future data. For instance, we find aCP(π+K∗0)+aCP(K+K̄∗0)=0 for ΔU=0 new physics and the opposite relative sign for the |ΔU|=1 case. One sum rule, connecting four decay modes, holds in both scenarios. We further extend our sum rules to certain differences of CP asymmetries from which the D production asymmetries drop out.

DOI： 10.1103/PhysRevD.111.035023

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arXiv

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Lepton flavor universality violations in semileptonic $b \to c$ transitions
have garnered attention over a decade. For $R_{H_c}={\rm{BR } }(H_b\to H_c
\tau\bar\nu_\tau)/{\rm{BR } }(H_b\to H_c \ell\bar\nu_\ell)$ with $\ell$ being
$e,\, \mu$, a sum rule among $R_{D}$, $R_{D^*}$ and $R_{\Lambda_c}$ was
proposed to check consistency in the experimental results independently of new
physics models. We revisit this relation from the perspective of the heavy
quark symmetry. We derive a sum rule holding exactly in the heavy quark limit
and clarify how model-dependent corrections are introduced in a realistic
situation.

DOI： 10.1007/JHEP05(2025)112

Open Access

arXiv

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その他リンク： http://arxiv.org/pdf/2501.09382v3

DOI： 10.22323/1.476.0414

出版者・発行元：Journal of High Energy Physics  

We perform a global statistical analysis of the two-Higgs-doublet model with generic sources of flavour violation using GAMBIT. This is particularly interesting in light of deviations from the Standard Model predictions observed in b→cτν¯ and b → sℓ⁺ℓ⁻ transitions as well as the indications for a charged Higgs with a mass of 130 GeV in top quark decays. Including all relevant constraints from precision, flavour and collider observables, we find that it is possible to simultaneously explain both the charged and neutral current B anomalies. We study the impact of using different values for the W mass and the Standard Model prediction for the anomalous magnetic moment of the muon and provide predictions for observables that can probe our model in the future such as lepton flavour violation searches at Belle II and Higgs coupling strength measurements at the high-luminosity LHC.

DOI： 10.1007/JHEP11(2024)133

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arXiv

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その他リンク： http://arxiv.org/pdf/2410.10493v1

掲載種別：研究論文（学術雑誌）   出版者・発行元：Physical Review D  

The measurements of the lepton flavor universality (LFU) in B(B¯→D(∗)lν¯) indicate a significant deviation from the standard model prediction at a 3-4σ level, revealing a violation of the LFU (RD(∗) anomaly). It is known that the RD(∗) anomaly can be easily accommodated by an SU(2)L-singlet vector leptoquark (LQ) coupled primarily to third-generation fermions, whose existence is further motivated by a partial gauge unification. In general, such a LQ naturally leads to additional CP-violating phases in the LQ interactions. In this paper, we point out that the current RD(∗) anomaly prefers the CP-violating interaction although B(B¯→D(∗)lν¯) are CP-conserving observables. The CP-violating LQ predicts a substantial size of the bottom-quark electric dipole moment (EDM), the chromo-EDM, and also the tau-lepton EDM. Eventually at low energy, the nucleon and electron EDMs are radiatively induced. Therefore, we conclude that the RD(∗) anomaly with the SU(2)L-singlet vector LQ provides unique predictions: neutron and proton EDMs with opposite signs and a magnitude of O(10-27) e cm, and suppressed electron EDM. Furthermore, we show that a similar EDM pattern is predicted in an SU(2)L-doublet scalar LQ scenario that can accommodate the RD(∗) anomaly as well. These EDM signals could serve as crucial indicators in future experiments.

DOI： 10.1103/PhysRevD.110.075008

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arXiv

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Physical Review D  

Recently, several new experimental results of the test of lepton flavor universality (LFU) in B → D^(∗) semileptonic decays were announced: the first result of R<inf>D</inf> from the LHCb run 1 data, the first results of R<inf>D</inf> and R<inf>D</inf>∗ from the LHCb run 2 data, and the first result of R<inf>D</inf>∗ from the Belle II collaboration. Including these new data, a global analysis still prefers the violation of the LFU between the tau and light leptons. A new world average of the data from the BABAR, LHCb, Belle, and Belle II collaborations is R<inf>D</inf> = 0.342 ± 0.026 and R<inf>D</inf>∗ = 0.287 ± 0.012. Including this new data, we update a circumstance of the b → cτν̄ measurements and their implications for new physics (NP). Incorporating recent developments for the B → D^(∗) form factors in the Standard Model, we observe a 4.4σ deviation from the Standard Model prediction. Our updates also include model-independent NP formulas 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 NP scenarios with the use of the precise measurements of the polarization observables in B → D^(∗)τν̄ at the Belle II and the high-p<inf>T</inf> flavored-tail searches at the LHC. We also discuss an impact on the LFU violation in ϒ → l⁺l⁻

DOI： 10.1103/PhysRevD.110.075005

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arXiv

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出版者・発行元：Physical Review D  

We show that supplementing the Standard Model by only a second Higgs doublet, a combined explanation of h→eτ, h→μτ, b→sℓ+ ℓ-, the W mass and R(D(∗)) as well as the excess in t→bH+(130 GeV)→bb¯c is possible. While this requires flavor violating couplings, the stringent bounds from, e.g., μ→eγ, τ→μγ, Bs-B¯s mixing, b→sγ, low mass dijet, and pp→H+H-→τ+τ-νν¯ searches can be avoided. However, the model is very constrained; it inevitably predicts a shift in the SM Higgs coupling strength to tau leptons as well as a nonzero t→hc rate, as indeed preferred by recent measurements. We study three benchmark points providing such a simultaneous explanation and calculate their predictions, including collider signatures which can be tested with upcoming LHC run-3 data.

DOI： 10.1103/PhysRevD.110.015014

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Web of Science

Scopus

$\mu$TRISTAN is a realistic high energy lepton collider based on the existing
technology aiming at indirect and direct search for the physics beyond the
standard model (SM). We propose a measurement to determine one of the most
prominent parameters of the SM, weak mixing angle to test the SM and probe the
new physics effect in M\o ller-like scattering with a wide range of interaction
scales. We show that this experiment not only can determine the weak mixing
angle with percent to milli-level accuracy but also scan over a wide range of
interaction scales that have never been archived in a single experiment
elsewhere.

arXiv

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その他リンク： http://arxiv.org/pdf/2406.04500v1

DOI： 10.1103/PhysRevD.109.075007

Open Access