We compute next-to-next-to-leading order perturbative corrections to the decay width difference of mass eigenstates and the charge-parity asymmetry $\textit{a}$ in flavour-specific decays of neutral $\textit{B}$ mesons. In our calculation we take into account the full dependence on the charm and bottom quark masses for the current-current operator contributions up to three-loop order. Special emphasis is put on the proper construction of the so-called |∆$\textit{B}$| = 2 theory such that Fierz symmetry is preserved. We provide updated phenomenological predictions, for ∆Γ, ∆Γ/∆$\textit{M}$ and $\textit{a}$ for the $\textit{B}$ and $\textit{B}$ system, including a detailed analysis of the uncertainties of our predictions. The calculated NNLO correction reduce the perturbative uncertainty of the leading term of the 1/$\textit{m}$ expansion of the width difference ∆Γ in the $\textit{B}$ system to the level of the current experimental error. The uncertainty of our prediction ∆Γ = (0.077 ± 0.016) ps is dominated by the sub-leading term of this expansion. We further illustrate how better future measurements of ∆Γ and $${a}_{\text{fs}}^{d}$$ will help to gain a better understanding of $${B}_{d}{\text -}{\overline{B} }_{d}$$ mixing.

Germany

Marvin Gerlach

Ulrich Nierste

Pascal Reeck

Vladyslav Shtabovenko

Matthias Steinhauser

Current-current operator contribution to the decay matrix in $\textit{B}$-meson mixing at next-to-next-to-leading order of QCD

<p>An axionlike particle <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>a</mi></math> (ALP) can explain the excess of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo stretchy="false">→</mo><mi>K</mi><mo>+</mo><mtext>invisible</mtext></math> events at Belle II. However, many analyses of ALP scenarios are oversimplified. We revisit the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo stretchy="false">→</mo><mi>K</mi><mi>a</mi></math> transition rate in a popular minimal and UV complete model with two Higgs doublets (2HDM) and a complex singlet [Dine-Fischler-Srednicki-Zhitnitsky (DFSZ) model]. To this end we compare our results with previous studies which derived the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mover accent="true"><mi>b</mi><mo stretchy="false">¯</mo></mover><mi>s</mi><mi>a</mi></math> vertex from the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mover accent="true"><mi>b</mi><mo stretchy="false">¯</mo></mover><mi>s</mi><mi>A</mi></math> vertex, where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>A</mi></math> is the heavy pseudoscalar of the 2HDM, in terms of an <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>a</mi><mo>−</mo><mi>A</mi></math> mixing angle. We find this approach to work only at the leading one-loop order, while it fails at the two-loop level. Furthermore, while an approximate <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>Z</mi><mn>2</mn></msub></math> symmetry suppresses the leading-order amplitude by a factor of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>1</mn><mo>/</mo><mi>tan</mi><mi>β</mi></math>, which is the ratio of the two vacuum expectation values of the Higgs doublets, we find the two-loop contribution unsuppressed and phenomenologically relevant for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>tan</mi><mi>β</mi><mo>≳</mo><mn>5</mn></math>. We determine the allowed parameter space and underline the importance of better searches for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="normal">ϒ</mi><mo stretchy="false">→</mo><mi>γ</mi><mo>+</mo><mi>invisible</mi></mrow></math> and for a possible excess in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo stretchy="false">→</mo><mi>K</mi><msup><mi>μ</mi><mo>+</mo></msup><msup><mi>μ</mi><mo>−</mo></msup></math>. We further study the low-energy axion effective theory which leads to a divergent and basis-dependent amplitude. As a conceptual result, we clarify the ambiguities and identify which low-energy framework is consistent with the DFSZ model.</p>

Xiyuan Gao

<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo stretchy="false">→</mo><mi>K</mi><mo>+</mo></math> axionlike particles: Effective versus UV-complete models and enhanced two-loop contributions

We show that $\textit{D}$ → $\textit{Pη}$′ decay amplitudes, where $\textit{P}$ = $\textit{K}$, $\textit{π}$, $\textit{η}$, cannot be simply related to their $\textit{D}$ → $\textit{Pη}$ counterparts with a single $\textit{η}$ –$\textit{η}$ mixing angle. We propose a novel, consistent treatment of $\textit{η}$ –$\textit{η}$ mixing for application in $\textit{D}$ → $\textit{Pη}$ and $\textit{D}$ → $\textit{Pη}$′ decays. Using this framework, we perform a global analysis of $\textit{D}$ → $\textit{Pη}$′ decays employing SU(3) symmetry including linear SU(3) breaking. We find that the assumption of 30% SU(3) breaking is in slight tension (2.5$\textit{σ}$) with the data when compared to a fit that allows for 50% SU(3) breaking, the latter giving a perfect description of the data. In order to allow for further scrutinization of SU(3) -breaking effects in the future, we give branching ratio predictions for all $\textit{D}$ → $\textit{Pη}$′ modes. Our predictions deviate from the current data in case of the branching ratios $$ \mathcal{B} $$ ( $$ {D}_s^{+} $$ → $\textit{K}$ $\textit{η}$′) and $$ \mathcal{B} $$ ($\textit{D}$ → $\textit{K}$ $\textit{η}$′). Future more precise measurements of these channels are therefore highly important in order to clarify the quality of the SU(3) expansion in nonleptonic $\textit{D}$ → $\textit{Pη}$′ decays.

Netherlands

Carolina Bolognani

United Kingdom

Stefan Schacht

K. Vos

Anatomy of non-leptonic two-body decays of charmed mesons into final states with $\textit{η}$′

Scalar leptoquarks (LQ) with masses between 2 TeV and 50 TeV are prime candidates to explain deviations between measurements and Standard-Model predictions in decay observables of $\textit{b}$-flavored hadrons (“flavor anomalies”). Explanations of low-energy data often involve $$ \mathcal{O} $$ (1) LQ-quark-lepton Yukawa couplings, especially when collider bounds enforce a large LQ mass. This calls for the calculation of radiative corrections involving these couplings. Studying such corrections to LQ-mediated $\textit{b}$ → $\textit{cτν}$ and $\textit{b}$ → $\textit{sℓ}$ $\textit{ℓ}$ amplitudes, we find that they can be absorbed into finite renormalizations of the LQ Yukawa couplings. If one wants to use Yukawa couplings extracted from low-energy data for the prediction of on-shell LQ decay rates, one must convert the low-energy couplings to their high-energy counterparts, which subsume the corrections to the on-shell LQ-quark-lepton vertex. We present compact formulae for these correction factors and find that in scenarios with $\textit{S}$ , $\textit{R}$ , or $\textit{S}$ LQ the high-energy coupling is always smaller than the low-energy one, which weakens the impact of collider data on the determination of the allowed parameter spaces. For the $\textit{R}$ scenario addressing $\textit{b}$ → $\textit{cτν}$, in which one of the two involved Yukawa coupling must be significantly larger than 1, we find this coupling reduced by 15% at high energy. If both $\textit{S}$ and $\textit{R}$ are present, the high-energy coupling can also be larger and the size of the correction is unbounded, because tree contribution and vertex corrections involve different couplings. We further present the conversion formula to the $$ \overline{\textrm{MS}} $$ scheme for the Yukawa couplings of the $\textit{S}$ scenario.

United States

Innes Bigaran

Rodolfo Capdevilla

Radiative corrections relating leptoquark-fermion couplings probed at low and high energy

<p>Charge-parity (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math>) 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 <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math> asymmetry measurements in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>D</mi></mrow><mrow><mn>0</mn></mrow></msup><mo stretchy="false">→</mo><msup><mrow><mi>K</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>K</mi></mrow><mrow><mo>−</mo></mrow></msup></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>D</mi><mn>0</mn></msup><mo stretchy="false">→</mo><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>−</mo></msup></math> decays with unprecedented accuracy: <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>a</mi><mrow><mi>C</mi><mi>P</mi></mrow></msub><mo stretchy="false">(</mo><msup><mi>K</mi><mo>+</mo></msup><msup><mi>K</mi><mo>−</mo></msup><mo stretchy="false">)</mo><mo>=</mo><mo stretchy="false">(</mo><mn>7.7</mn><mo>±</mo><mn>5.7</mn><mo stretchy="false">)</mo><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>4</mn></mrow></msup></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>a</mi></mrow><mrow><mi>C</mi><mi>P</mi></mrow></msub><mo stretchy="false">(</mo><msup><mrow><mi>π</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>π</mi></mrow><mrow><mo>−</mo></mrow></msup><mo stretchy="false">)</mo><mo>=</mo><mo stretchy="false">(</mo><mn>23.2</mn><mo>±</mo><mn>6.1</mn><mo stretchy="false">)</mo><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>4</mn></mrow></msup></mrow></math>, with the latter quantity inferred from the precise measurement of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="normal">Δ</mi><msub><mrow><mi>a</mi></mrow><mrow><mi>C</mi><mi>P</mi></mrow></msub><mo>=</mo><msub><mrow><mi>a</mi></mrow><mrow><mi>C</mi><mi>P</mi></mrow></msub><mo stretchy="false">(</mo><msup><mrow><mi>K</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>K</mi></mrow><mrow><mo>−</mo></mrow></msup><mo stretchy="false">)</mo><mo>−</mo><msub><mrow><mi>a</mi></mrow><mrow><mi>C</mi><mi>P</mi></mrow></msub><mo stretchy="false">(</mo><msup><mrow><mi>π</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>π</mi></mrow><mrow><mo>−</mo></mrow></msup><mo stretchy="false">)</mo><mo>=</mo><mspace linebreak="goodbreak"></mspace><mo stretchy="false">(</mo><mo>−</mo><mn>15.7</mn><mo>±</mo><mn>2.9</mn><mo stretchy="false">)</mo><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>4</mn></mrow></msup></mrow></math>. When interpreted within the Standard Model, these values indicate a breakdown of the approximate <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>U</mi></math>-spin symmetry of QCD. If, however, this symmetry holds and the data stem from new physics, other <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math> asymmetries should be enhanced as well. We derive <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math> asymmetry sum rules based on SU(3) flavor symmetry for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi></math> 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 <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Δ</mi><mi>U</mi><mo>=</mo><mn>0</mn></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">|</mo><mi mathvariant="normal">Δ</mi><mi>U</mi><mo stretchy="false">|</mo><mo>=</mo><mn>1</mn></math> 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 <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>a</mi></mrow><mrow><mi>C</mi><mi>P</mi></mrow></msub><mo stretchy="false">(</mo><msup><mrow><mi>π</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>K</mi></mrow><mrow><mo>*</mo><mn>0</mn></mrow></msup><mo stretchy="false">)</mo><mo>+</mo><msub><mrow><mi>a</mi></mrow><mrow><mi>C</mi><mi>P</mi></mrow></msub><mo stretchy="false">(</mo><msup><mrow><mi>K</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mover accent="true"><mrow><mi>K</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover></mrow><mrow><mo>*</mo><mn>0</mn></mrow></msup><mo stretchy="false">)</mo><mo>=</mo><mn>0</mn></mrow></math> for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">Δ</mi><mi>U</mi><mo>=</mo><mn>0</mn></math> new physics and the opposite relative sign for the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">|</mo><mi mathvariant="normal">Δ</mi><mi>U</mi><mo stretchy="false">|</mo><mo>=</mo><mn>1</mn></math> case. One sum rule, connecting four decay modes, holds in both scenarios. We further extend our sum rules to certain differences of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math> asymmetries from which the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>D</mi></math> production asymmetries drop out.</p>

Japan

Syuhei Iguro

Emil Overduin

Maurice Schüßler

<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>SU</mi><mo stretchy="false">(</mo><mn>3</mn><mo stretchy="false">)</mo></mrow><mrow><mi mathvariant="normal">F</mi></mrow></msub></mrow></math> sum rules for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math> asymmetries of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>D</mi><mrow><mo stretchy="false">(</mo><mi>s</mi><mo stretchy="false">)</mo></mrow></msub></math> decays

In this paper we study the bounds that can be inferred on New Physics couplings to heavy sterile neutrinos from the recent measurements performed by the Belle collaboration of the angular analysis of $$ B\to {D}^{\ast}\ell {\overline{\nu}}_{\ell } $$ decays, with = , . Indeed, a sterile neutrino may lead to competing $$ B\to {D}^{\ast}\ell \overline{N} $$ decays and Belle might have measured an incoherent sum of these two independent channels. After reviewing the theoretical formalism required to describe this phenomenon in full generality, we first perform a bump hunt in the $$ {M}_{\textrm{miss}}^2 $$ Belle distribution to search for evidences of an additional massive neutrino. We found in such a way a small hint at $$ {M}_{\textrm{miss}}^2 $$ ∼ (354 MeV) . However, the Belle angular analysis is sensitive to masses up to $$ \mathcal{O} $$ (50 MeV), preventing us to further inspect this hint. Nevertheless, we study the potential impact of this additional channel in the allowed mass range on the measured angular distributions and extract model-independent bounds on the new-physics couplings which could mediate such an interaction. In particular, in the mass window here inspected, we obtain the most stringent bounds for vector and left-handed scalar operators to date.

Florian Bernlochner

Spain

Marco Fedele

Tim Kretz

Markus Prim

Model independent bounds on heavy sterile neutrinos from the angular distribution of B → D

We present a Two-Higgs-Doublet Model in which the structure of the quark Yukawa matrices is governed by three spurions breaking the flavour symmetries of the quark Yukawa sector. The model naturally suppresses flavour-changing neutral current (FCNC) amplitudes in the down-type sector, but permits sizable FCNC couplings in the up sector. We calculate the branching ratio of B  s   → μ + μ  −  to leading and next-to-leading order of QCD for the case with FCNC couplings of the heavy neutral Higgs bosons to up-type quarks and verify that all counterterms follow the pattern dictated by the spurion expansion of the Yukawa matrices. We find correlations between B  s   → μ + μ  − , b → sγ, and the Higgs masses. The  $${B}_{s}-{\overline{B} }_{s}$$  mixing amplitude is naturally suppressed in the model but can probe a portion of the parameter space with very heavy Higgs bosons.

Martin Lang

B  s  → μ + μ − in a two-Higgs-doublet model with flavour-changing up-type Yukawa couplings

Leptoquarks with masses between 2 TeV and 50 TeV are commonly invoked to explain deviations between data and Standard-Model (SM) predictions of several observables in the decays   <math> <mi>b</mi> <mo>→</mo> <mi>cτ</mi> <mover> <mi>ν</mi> <mo>¯</mo> </mover> </math>  $$ b\to c\tau \overline{\nu} $$  and b → sℓ + ℓ  −  with ℓ = e, μ. While Leptoquarks appear in theories unifying quarks and leptons, the corresponding unification scale M QLU is typically many orders of magnitude above this mass range. We study the case that the mass gap between the electroweak scale and M QLU is only populated by scalar Leptoquarks and SM particles, restricting ourselves to scenarios addressing the mentioned flavour anomalies, and determine the renormalisation-group evolution of Leptoquark couplings to fermions below M QLU. In the most general case, we consider three SU(2) triplet Leptoquarks   <math> <msubsup> <mi>S</mi> <mn>3</mn> <mi>ℓ</mi> </msubsup> </math>  $$ {S}_3^{\ell } $$ , ℓ = e, μ, τ, which couple quark doublets to the lepton doublet (ν  ℓ , ℓ  − ) to address the b → sℓ + ℓ  −  anomalies. In this case, we find a scenario in which the Leptoquark couplings to electrons and muons are driven to the same infrared fixed point, so that lepton flavour universality emerges dynamically. However, the corresponding fixed point for the couplings to taus is necessarily opposite in sign, leading to a unique signature in b → sτ + τ  − . For   <math> <mi>b</mi> <mo>→</mo> <mi>cτ</mi> <mover> <mi>ν</mi> <mo>¯</mo> </mover> </math>  $$ b\to c\tau \overline{\nu} $$  we complement these with either an SU(2) singlet   <math> <msubsup> <mi>S</mi> <mn>1</mn> <mi>τ</mi> </msubsup> </math>  $$ {S}_1^{\tau } $$  or doublet   <math> <msubsup> <mi>R</mi> <mn>2</mn> <mi>τ</mi> </msubsup> </math>  $$ {R}_2^{\tau } $$  and study further the cases that also these Leptoquarks come in three replicas. The fixed point solutions for the   <math> <msubsup> <mi>S</mi> <mn>3</mn> <mi>ℓ</mi> </msubsup> </math>  $$ {S}_3^{\ell } $$  couplings explain the b → sℓ + ℓ  −  data for   <math> <msubsup> <mi>S</mi> <mn>3</mn> <mrow> <mi>e</mi> <mo>,</mo> <mi>μ</mi> </mrow> </msubsup> </math>  $$ {S}_3^{e,\mu } $$  masses between 14 and 15 TeV, according to the scenario.   <math> <mi>b</mi> <mo>→</mo> <mi>cτ</mi> <mover> <mi>ν</mi> <mo>¯</mo> </mover> </math>  $$ b\to c\tau \overline{\nu} $$  data can only be fully explained by couplings exceeding their fixed-point values and evolving into Landau poles at high energies, so that one can place an upper bound on M QLU between 108 and 1011 GeV.

Felix Wuest

Renormalisation group analysis of scalar Leptoquark couplings addressing flavour anomalies: emergence of lepton-flavour universality

Form factors are a crucial theory input in order to extract <math><mo>|</mo><msub><mi>V</mi><mrow><mi>c</mi><mi>b</mi></mrow></msub><mo>|</mo></math> from <math><mi>B</mi><mo>→</mo><msup><mi>D</mi><mrow><mo>(</mo><mo>*</mo><mo>)</mo></mrow></msup><mo>ℓ</mo><mi>ν</mi></math> decays, to calculate the Standard Model prediction for <math><mi>R</mi><mo>(</mo><msup><mi>D</mi><mrow><mo>(</mo><mo>*</mo><mo>)</mo></mrow></msup><mo>)</mo></math> and to assess the impact of new physics. In this context, the dispersive matrix approach, a first-principle calculation of the form factors, using no experimental data but rather only lattice QCD results as input, was recently applied to <math><mi>B</mi><mo>→</mo><msup><mi>D</mi><mrow><mo>(</mo><mo>*</mo><mo>)</mo></mrow></msup><mo>ℓ</mo><mi>ν</mi></math>. It predicts (within the Standard Model) a much milder tension with the <math><mi>R</mi><mo>(</mo><msup><mi>D</mi><mo>*</mo></msup><mo>)</mo></math> measurements than the other form factor approaches, while at the same time giving a value of <math><mo>|</mo><msub><mi>V</mi><mrow><mi>c</mi><mi>b</mi></mrow></msub><mo>|</mo></math> compatible with the inclusive value. However, this comes at the expense of creating tensions with differential <math><mi>B</mi><mo>→</mo><msup><mi>D</mi><mo>*</mo></msup><mo>ℓ</mo><mi>ν</mi></math> distributions (with light leptons). In this article, we explore the implications of using the dispersive matrix method form factors, in light of the recent Belle (II) measurements of the longitudinal polarization fraction of the <math><msup><mi>D</mi><mo>*</mo></msup></math> in <math><mi>B</mi><mo>→</mo><msup><mi>D</mi><mo>*</mo></msup><mo>ℓ</mo><mi>ν</mi></math> with light leptons, <math><msubsup><mi>F</mi><mi>L</mi><mo>ℓ</mo></msubsup></math>, and the forward-backward asymmetry, <math><msubsup><mi>A</mi><mi>FB</mi><mo>ℓ</mo></msubsup></math>. We find that the dispersive matrix approach predicts a Standard Model value of <math><msubsup><mi>F</mi><mi>L</mi><mo>ℓ</mo></msubsup></math> that is in significant tension with these measurements, while mild deviations in <math><msubsup><mi>A</mi><mi>FB</mi><mo>ℓ</mo></msubsup></math> appear. Furthermore, <math><msubsup><mi>F</mi><mi>L</mi><mo>ℓ</mo></msubsup></math> is very insensitive to new physics such that the latter cannot account for the tension between dispersive matrix predictions and its measurement. While this tension can be resolved by deforming the original dispersive matrix form factor shapes within a global fit, a tension in <math><mi>R</mi><mo>(</mo><msup><mi>D</mi><mo>*</mo></msup><mo>)</mo></math> reemerges. As this tension is milder than for the other form factors, it can be explained by new physics not only in the tau lepton channel but also in the light lepton modes.

Monika Blanke

Switzerland

Andreas Crivellin

Italy

Silvano Simula

France

Ludovico Vittorio

Discriminating <math><mi>B</mi><mo>→</mo><msup><mi>D</mi><mo>*</mo></msup><mo>ℓ</mo><mi>ν</mi></math> form factors via polarization observables and asymmetries

Measurements of the branching ratios of <math><mi>B</mi><mo>→</mo><msup><mi>D</mi><mrow><mo>(</mo><mo>*</mo><mo>)</mo></mrow></msup><mi>τ</mi><mover><mi>ν</mi><mo>¯</mo></mover><mo>/</mo><mi>B</mi><mo>→</mo><msup><mi>D</mi><mrow><mo>(</mo><mo>*</mo><mo>)</mo></mrow></msup><mo>ℓ</mo><mover><mi>ν</mi><mo>¯</mo></mover></math> and <math><msub><mi>B</mi><mi>c</mi></msub><mo>→</mo><mi>J</mi><mo>/</mo><mi>ψ</mi><mi>τ</mi><mover><mi>ν</mi><mo>¯</mo></mover><mo>/</mo><msub><mi>B</mi><mi>c</mi></msub><mo>→</mo><mi>J</mi><mo>/</mo><mi>ψ</mi><mo>ℓ</mo><mover><mi>ν</mi><mo>¯</mo></mover></math> by the BABAR, Belle and LHCb collaborations consistently point towards an abundance of taus compared to channels with light leptons. However, the ratio <math><msub><mi>Λ</mi><mi>b</mi></msub><mo>→</mo><msub><mi>Λ</mi><mi>c</mi></msub><mi>τ</mi><mover><mi>ν</mi><mo>¯</mo></mover><mo>/</mo><msub><mi>Λ</mi><mi>b</mi></msub><mo>→</mo><msub><mi>Λ</mi><mi>c</mi></msub><mo>ℓ</mo><mover><mi>ν</mi><mo>¯</mo></mover></math> 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 <math><mn>2</mn><mi>σ</mi></math> or <math><mn>1.5</mn><mi>σ</mi></math>, depending on the <math><mi>R</mi><mo>(</mo><msub><mi>Λ</mi><mi>c</mi></msub><mo>)</mo></math> 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.

China

Teppei Kitahara

Ryoutaro Watanabe

Impact of <math><msub><mi>Λ</mi><mi>b</mi></msub><mo>→</mo><msub><mi>Λ</mi><mi>c</mi></msub><mi>τ</mi><mi>ν</mi></math> measurement on new physics in <math><mi>b</mi><mo>→</mo><mi>c</mi><mi>l</mi><mi>ν</mi></math> transitions