DOI： 10.1088/1361-6471/ae05b4

Open Access

Web of Science

Publisher：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

Publishing type：Research paper (scientific journal)  

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 more than $4\sigma$ discrepancy 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, $b \to c$ 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 $b\to c l \overline{\nu}$ 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

researchmap

Other Link： http://arxiv.org/pdf/2506.16027v1

Publishing type：Research paper (scientific journal)  

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

Open Access

Web of Science

Scopus

arXiv

researchmap

Other Link： http://arxiv.org/pdf/2412.15132v1

Publishing type：Research paper (scientific journal)  

The semi-leptonic $b \to c l \nu$ processes are receiving a lot of attention,
as the lepton flavor universality violation has been hinted by the measured
ratios $R_{D^{(*) } } = \Gamma(B \to D^{(*)} \tau\nu)/\Gamma(B \to D^{(*)}
\ell\nu)$ for $\ell = e,\mu$. Recently, it has also been pointed out that the
baryonic counterpart, $R_{\Lambda_c} = \Gamma (\Lambda_b \to \Lambda_c
\tau\nu)/\Gamma (\Lambda_b \to \Lambda_c \ell\nu)$, has a strong correlation
with $R_{D^{(*) } }$, referred to as the R ratio sum rule in this paper. The
correlation is almost independent of the new physics (NP) contributions and
hence can predict $R_{\Lambda_c}$ from the measured $R_{D^{(*) } }$. On the other
hand, we have fewer measurements and/or theoretical studies of the
semi-leptonic $b \to u l \nu$ processes, although the same arguments can be
applied to the ratios $R_\pi$, $R_\rho$, and $R_p$ 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 $R_X$ ratios in the presence
of model-independent 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 $R_X$ 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 $b \to u l \nu$ processes for the first time,
which provides a complementary motivation for observing these processes. In
addition, based on our model-independent results, we investigate how the
different NP scenarios work in the $b\to c$ and $b\to u$ sectors and perform a
combined study in the framework of SM effective field theory with specific
flavor symmetries.

DOI： 10.1007/JHEP07(2025)166

Open Access

Web of Science

Scopus

arXiv

researchmap

Publisher：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

Publisher：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

Language：Japanese   Publisher：The Physical Society of Japan  

<p>Large discrepancies in bottom-flavored physics have motivated intensive phenomenological studies for more than ten years. 3–4σ discrepancies between the experimental value and the prediction of the Standard Model (SM) of particle physics in <i>b</i>→<i>cτν</i> and <i>b</i>→<i>sll</i> transitions would imply new particles at TeV scale. In this commentary, we summarize the progress of these 10 years in the SM prediction and new physics interpretation of these hints. We discussed how to find the smoking gun signals of those particles in other bottomquark flavored observables, the large hadron collider, and electric dipole moments. We see that near future data will judge the interpretations by physics beyond the SM.</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

researchmap

Other Link： http://arxiv.org/pdf/2503.22256v1

Publishing type：Research paper (scientific journal)  

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
$D^0\to K^+ K^-$ and $D^0\to \pi^+\pi^-$ decays with unprecedented accuracy:
$a_{\rm{CP } }(K^+ K^-)=(7.7\pm5.7)\times 10^{-4}$ and
$a_{\rm{CP } }(\pi^+\pi^-)=(23.2\pm6.1)\times 10^{-4}$, with the latter quantity
inferred from the precise measurement of $\Delta a_{\rm{CP } } =\,
a_{\rm{CP } }(K^+ K^-) -a_{\rm{CP } }(\pi^+\pi^-) =\, (-15.7\pm2.9)\times 10^{-4}$.
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 $\rm{SU}(3)$ 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 $\Delta U=0$
and $|\Delta U|=1$ 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 $a_{\mathrm{CP } }(\pi^{+}K^{* 0}) + a_{\mathrm{CP } }(K^{+}\overline{K}^{*
0}) = 0$ for $\Delta U=0$ new physics and the opposite relative sign for the
$|\Delta U|=1$ 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

Open Access

Web of Science

Scopus

arXiv

researchmap

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

researchmap

Other Link： http://arxiv.org/pdf/2501.09382v3

DOI： 10.22323/1.476.0414

We perform a global statistical analysis of the two-Higgs-doublet model with
generic sources of flavour violation using \textsf{GAMBIT}. This is
particularly interesting in light of deviations from the Standard Model
predictions observed in $b\to c\tau\bar \nu$ and $b\to s\ell^+\ell^-$
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 $g-2$ 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

Open Access

Web of Science

Scopus

arXiv

researchmap

Other Link： http://arxiv.org/pdf/2410.10493v1

Publishing type：Research paper (scientific journal)  

The measurements of the lepton flavor universality (LFU) in
$\mathcal{B}({\bar{B } } \to D^{(\ast)} l \bar{\nu})$ indicate a significant
deviation from the standard model prediction at a 3-4$\sigma$ level, revealing
a violation of the LFU ($R_{D^{(\ast) } }$ anomaly). It is known that the
$R_{D^{(\ast) } }$ 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 $R_{D^{(\ast) } }$
anomaly prefers the $CP$-violating interaction although $\mathcal{B}({\bar{B } }
\to D^{(\ast)} l\bar{\nu})$ 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 $R_{D^{(\ast) } }$ anomaly with the $SU(2)_L$-singlet vector LQ provides
unique predictions: neutron and proton EDMs with opposite signs and a magnitude
of $\mathcal{O}(10^{-27})\,e$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 $R_{D^{(\ast) } }$ anomaly as well. These EDM
signals could serve as crucial indicators in future experiments.

DOI： 10.1103/PhysRevD.110.075008

Open Access

Web of Science

Scopus

arXiv

researchmap

Publishing type：Research paper (scientific journal)  

Recently, several new experimental results of the test of lepton flavor
universality (LFU) in $B\to D^{(\ast)}$ semi-leptonic decays were announced:
the first result of $R_{D}$ from the LHCb Run 1 data, the first results of
$R_{D}$ and $R_{D^\ast}$ from the LHCb Run 2 data, and the first result of
$R_{D^\ast}$ 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 $R_{D} = 0.342 \pm 0.026$ and $R_{D^{\ast } } = 0.287
\pm 0.012$. Including this new data, we update a circumstance of the $b \to c
\tau \overline\nu$ measurements and their implications for new physics (NP).
Incorporating recent developments for the $B \to D^{(\ast)}$ form factors in
the Standard Model (SM), we observe a $4.4 \sigma$ deviation from the SM
prediction. Our updates also include; model-independent 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 NP 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 $\Upsilon \to l^+
l^-$.

DOI： 10.1103/PhysRevD.110.075005

Open Access

Web of Science

Scopus

arXiv

researchmap

Publisher：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

Open Access

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

researchmap

Other Link： http://arxiv.org/pdf/2406.04500v1

DOI： 10.1103/PhysRevD.109.075007

Open Access