The Standard Model (SM) is lepton flavor universal, and the recent measurements of lepton flavor universality in <inline-formula><tex-math id='TM0002' notation='LaTeX'>$B \rightarrow (K,K^{*})\ell ^{+}\ell ^{-}$</tex-math></inline-formula>, <inline-formula><tex-math id='TM0003' notation='LaTeX'>$\ell = \mu , \,\, e$</tex-math></inline-formula> decays now lie close to the SM predictions. However, this is not the case for the <inline-formula><tex-math id='TM0004' notation='LaTeX'>$\tau$</tex-math></inline-formula> to <inline-formula><tex-math id='TM0005' notation='LaTeX'>$\mu$</tex-math></inline-formula> ratios in these decays, where there is still some window open for the new physics (NP), and to accommodate them various extensions to the SM are proposed. It will be interesting to identify some observables that are not only sensitive in the parametric space of such NP models but also have some discriminatory power. We find that the polarization of the <inline-formula><tex-math id='TM0006' notation='LaTeX'>$K^{*}$</tex-math></inline-formula> may play an important role; therefore, we have computed the unpolarized and polarized lepton flavor universality ratios of <inline-formula><tex-math id='TM0007' notation='LaTeX'>$\tau$</tex-math></inline-formula> to <inline-formula><tex-math id='TM0008' notation='LaTeX'>$\mu$</tex-math></inline-formula> in <inline-formula><tex-math id='TM0009' notation='LaTeX'>$B\rightarrow K^{*}\ell ^{+}\ell ^{-}$</tex-math></inline-formula>, <inline-formula><tex-math id='TM0010' notation='LaTeX'>$\ell = \mu , \tau$</tex-math></inline-formula> decays. The calculation shows that in most cases, the values of the various proposed observables fall within the current experimental sensitivity, and their study in some ongoing and future experiments will serve as a tool to segregate the variants of the NP models.

Pakistan

Switzerland

Ishtiaq Ahmed

Saba Shafaq

M Jamil Aslam

Saadi Ishaq

Polarized and Unpolarized ℛ K* in and beyond the SM

Recent measurements of the lepton flavor universality ratios <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>R</mi><mi>K</mi><mrow><mi>μ</mi><mi>e</mi></mrow></msubsup></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>R</mi><msup><mi>K</mi><mo>*</mo></msup><mrow><mi>μ</mi><mi>e</mi></mrow></msubsup></math> in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo stretchy="false">→</mo><mrow><mo stretchy="false">(</mo><mi>K</mi><mo>,</mo><msup><mi>K</mi><mo>*</mo></msup><mo stretchy="false">)</mo></mrow><msup><mi>μ</mi><mo>+</mo></msup><msup><mi>μ</mi><mo>−</mo></msup><mrow><mo stretchy="false">(</mo><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup><mo stretchy="false">)</mo></mrow></math> at LHCb align with the Standard Model predictions, necessitating a search for the complementary decay modes. In this context, we derive the angular decay distributions of the four-fold <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>B</mi><mo stretchy="false">→</mo><msub><mrow><mi>K</mi></mrow><mrow><mn>1</mn></mrow></msub><mo stretchy="false">(</mo><mn>1270</mn><mo>,</mo><mn>1400</mn><mo stretchy="false">)</mo><mspace linebreak="goodbreak"></mspace><mo stretchy="false">(</mo><mo stretchy="false">→</mo><mi>V</mi><mi>P</mi><mo stretchy="false">)</mo><msup><mrow><mi>μ</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>μ</mi></mrow><mrow><mo>−</mo></mrow></msup></mrow></math> decays, where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>K</mi><mn>1</mn></msub></math> is an axial-vector meson, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>V</mi><mo>=</mo><mi>ρ</mi><mo>,</mo><msup><mi>K</mi><mo>*</mo></msup></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>P</mi><mo>=</mo><mi>K</mi></mrow></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>π</mi></mrow></math>. Considering the weak effective Hamiltonian with vector and axial-vector new physics operators, and employing the helicity formalism, we obtain the four-dimensional differential decay distributions and extract various physical observables. These include differential branching ratios, lepton forward-backward asymmetry, forward-backward asymmetry for transversely polarized <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>K</mi><mn>1</mn></msub></math> meson, longitudinal and transverse polarization fractions of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>K</mi><mn>1</mn></msub></math> meson, and normalized angular coefficients with longitudinally and transversely polarized final state vector meson <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>V</mi></math>, in the cascade decay <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>K</mi><mn>1</mn></msub><mo stretchy="false">→</mo><mi>V</mi><mi>P</mi></math>. Based on the latest global fit analysis data for all <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>b</mi><mo stretchy="false">→</mo><mi>s</mi></math> transitions, we predict the results of these observables in various bins of the square of the momentum transfer <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">(</mo><msup><mi>q</mi><mn>2</mn></msup><mo stretchy="false">)</mo></math>. Our findings indicate that these physical observables are not only sensitive to new physics but also can differentiate between various new physics scenarios in certain kinematical regions. The precise measurements of these observables in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo stretchy="false">→</mo><msub><mi>K</mi><mn>1</mn></msub><mo stretchy="false">(</mo><mn>1270</mn><mo>,</mo><mn>1400</mn><mo stretchy="false">)</mo><mo stretchy="false">(</mo><mo stretchy="false">→</mo><mi>V</mi><mi>P</mi><mo stretchy="false">)</mo><msup><mi>μ</mi><mo>+</mo></msup><msup><mi>μ</mi><mo>−</mo></msup></math> decays in current and future experiments will provide opportunities for complementary searches for physics beyond the Standard Model in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>b</mi><mo stretchy="false">→</mo><mi>s</mi><msup><mo>ℓ</mo><mo>+</mo></msup><msup><mo>ℓ</mo><mo>−</mo></msup></math> decays.

Faisal Munir Bhutta

Canada

Abdur Rehman

M. Jamil Aslam

Angular observables of the four-fold <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi><mo stretchy="false">→</mo><msub><mi>K</mi><mn>1</mn></msub><mo stretchy="false">(</mo><mn>1270</mn><mo>,</mo><mn>1400</mn><mo stretchy="false">)</mo><mo stretchy="false">(</mo><mo stretchy="false">→</mo><mi>V</mi><mi>P</mi><mo stretchy="false">)</mo><msup><mo>ℓ</mo><mo>+</mo></msup><msup><mo>ℓ</mo><mo>−</mo></msup></math> decays in and beyond the Standard Model

The rare three-body decay of a Higgs boson to a lepton–antilepton pair and a photon has begun to attract attention, after the first evidence for the <inline-formula><tex-math id='TM0002' notation='LaTeX'>$H\rightarrow Z\gamma$</tex-math></inline-formula> channel at CMS and ATLAS, which is a subprocess of <inline-formula><tex-math id='TM0003' notation='LaTeX'>$H \rightarrow \ell ^+ \ell ^- \gamma$</tex-math></inline-formula>. To investigate some important features of this process, we suggest that the polarized forward-backward and the photon polarization asymmetries could be useful to probe its important properties, such as the behavior of Yukawa coupling, resonance, and nonresonance contributions. Our analysis introduces a comprehensive framework to evaluate the aforementioned polarization-dependent observables. By analyzing the polarization effects of the final-state photon and lepton separately on forward-backward asymmetries, we demonstrate that loop-induced contributions play a significant role in investigating these asymmetries. Unlike the unpolarized case, where the interference effects of resonance and nonresonance effects are minimal, we show that polarization-dependent observables offer a powerful tool to analyze these features of this decay mode. Furthermore, these observables can provide a handy tool for probing possible signatures of physics beyond the SM.

Usman Hasan

A Uzair

M Junaid

Bilal Tariq

Shahin Iqbal

Polarization-Dependent Observables in <italic>H</italic> &#8594; &#8467; + &#8467; &#8211; &#947; in the SM

Recently, the experimental measurements of the branching ratios and different polarization asymmetries for processes occurring through flavor-changing-charged current   $ (b\rightarrow c\tau\overline{\nu}_{\tau}) $  transitions by BABAR, Belle, and LHCb have revealed some significant differences from the corresponding Standard Model (SM) predictions. This has triggered an interest to search for physics beyond the SM in the context of various new physics (NP) models and using the model-independent weak effective Hamiltonian (WEH). Assuming left-handed neutrinos, we add the dimension-six vector, (pseudo-)scalar, and tensor operators with complex Wilson coefficients (WCs) to the SM WEH. Using 60%, 30%, and 10% constraints resulting from the branching ratio of   $ (b\rightarrow c\tau\overline{\nu}_{\tau}) $  , we reassess the parametric space of these new physics WCs accommodating the current anomalies based on the most recent HFLAV data of   $ (b\rightarrow c\tau\overline{\nu}_{\tau}) $   and   $ (b\rightarrow c\tau\overline{\nu}_{\tau}) $   and Belle data of   $ (b\rightarrow c\tau\overline{\nu}_{\tau}) $   and   $ (b\rightarrow c\tau\overline{\nu}_{\tau}) $  . We find that the allowed parametric region of left-handed scalar couplings strongly depends on the constraints of the   $ (b\rightarrow c\tau\overline{\nu}_{\tau}) $   branching ratio, and the maximum pull from the SM predictions results from the &lt;60% branching ratio limit. Also, the parametric region changes significantly if we extend the analysis by adding LHCb data of   $ (b\rightarrow c\tau\overline{\nu}_{\tau}) $   and   $ (b\rightarrow c\tau\overline{\nu}_{\tau}) $  . Furthermore, due to the large uncertainties in the measurements of   $ (b\rightarrow c\tau\overline{\nu}_{\tau}) $   and   $ (b\rightarrow c\tau\overline{\nu}_{\tau}) $  , we derive the sum rules which complement them with   $ (b\rightarrow c\tau\overline{\nu}_{\tau}) $   and   $ (b\rightarrow c\tau\overline{\nu}_{\tau}) $  . Using the best-fit points of the new complex WCs along with the latest measurements of   $ (b\rightarrow c\tau\overline{\nu}_{\tau}) $  , we predict the numerical values of the observable   $ (b\rightarrow c\tau\overline{\nu}_{\tau}) $  ,   $ (b\rightarrow c\tau\overline{\nu}_{\tau}) $   , and   $ (b\rightarrow c\tau\overline{\nu}_{\tau}) $   from the sum rules. The simultaneous dependence of abovementioned physical observables on the NP WCs is established by plotting their correlation with   $ (b\rightarrow c\tau\overline{\nu}_{\tau}) $   and   $ (b\rightarrow c\tau\overline{\nu}_{\tau}) $  , which are useful to discriminate between various NP scenarios. We find that the most significant impact of NP results from the WC   $ (b\rightarrow c\tau\overline{\nu}_{\tau}) $  . Finally, we study the impact of these NP couplings on various angular and   $ (b\rightarrow c\tau\overline{\nu}_{\tau}) $   triple product asymmetries that could be measured in some ongoing and future experiments. The precise measurements of these observables are important to check the SM and extract the possible NP.

Muhammad Arslan

Tahira Yasmeen

Muhammad Jamil Aslam

Analysis of anomalies using weak effective Hamiltonian with complex couplings and their impact on various physical observables

Abstract Experimental studies of the observables associated with  transitions in semileptonic B-meson decays at BaBar, Belle, and LHCb have shown some deviations from the Standard Model predictions, consequently providing a handy tool to probe the possible new physics (NP). In this context, we first revisit the impact of recent measurements of  and  on the parametric space of the NP scenarios. In addition, we include the  data in the analysis and find that their influence on the best-fit point and the parametric space is mild. Using the recent HFLAV data, after validating the well established sum rule of , we derive a similar sum rule for . Furthermore, according to the updated data, we modify the correlation among the different observables, giving us their interesting interdependence. Finally, to discriminate the various NP scenarios, we plot the different angular observables and their ratios for  against the transfer momentum square , using the  and  parametric space of considered NP scenarios. By implementing the collider bounds on NP Wilson coefficients (WCs), we find that the parametric space of some NP WCs is significantly restrained. To see the clear influence of NP on the amplitude of the angular observables, we also calculate their numerical values in different  bins and show them through bar plots. We hope that their precise measurements will help to discriminate various NP scenarios.

Probing New Physics in Light of Recent Developments in → Transitions

Based on the expectations that the lowest-lying doubly-bottom tetraquark <math><msub><mrow><mi>T</mi></mrow><mrow><mi>b</mi><mi>b</mi><mover><mrow><mi>u</mi></mrow><mrow><mo>¯</mo></mrow></mover><mover><mrow><mi>d</mi></mrow><mrow><mo>¯</mo></mrow></mover></mrow></msub></math> (<math><msup><mrow><mi>J</mi></mrow><mrow><mi>P</mi></mrow></msup><mo>=</mo><msup><mrow><mn>1</mn></mrow><mrow><mo>+</mo></mrow></msup></math>) and the bottom-charm tetraquark <math><msub><mrow><mi>T</mi></mrow><mrow><mi>b</mi><mi>c</mi><mover><mrow><mi>u</mi></mrow><mrow><mo>¯</mo></mrow></mover><mover><mrow><mi>d</mi></mrow><mrow><mo>¯</mo></mrow></mover></mrow></msub></math> (<math><msup><mrow><mi>J</mi></mrow><mrow><mi>P</mi></mrow></msup><mo>=</mo><msup><mrow><mn>0</mn></mrow><mrow><mo>+</mo></mrow></msup></math>) are stable against strong and electromagnetic decays, we work out a number of semileptonic and non-leptonic weak decays of these hadrons, making use of the heavy quark symmetry. In doing this, we concentrate on the exclusive decays involving also tetraquarks in the final states, i.e., transitions such as <math><msub><mrow><mi>T</mi></mrow><mrow><mi>b</mi><mi>b</mi><mover><mrow><mi>u</mi></mrow><mrow><mo>¯</mo></mrow></mover><mover><mrow><mi>d</mi></mrow><mrow><mo>¯</mo></mrow></mover></mrow></msub><mo>→</mo><msub><mrow><mi>T</mi></mrow><mrow><mi>b</mi><mi>c</mi><mover><mrow><mi>u</mi></mrow><mrow><mo>¯</mo></mrow></mover><mover><mrow><mi>d</mi></mrow><mrow><mo>¯</mo></mrow></mover></mrow></msub><mspace width="0.2em"></mspace><mo>(</mo><msup><mrow><mi>ℓ</mi></mrow><mrow><mo>−</mo></mrow></msup><msub><mrow><mi>ν</mi></mrow><mrow><mi>ℓ</mi></mrow></msub><mo>,</mo><mspace width="0.2em"></mspace><msup><mrow><mi>h</mi></mrow><mrow><mo>−</mo></mrow></msup><mo>)</mo></math> and <math><msub><mrow><mi>T</mi></mrow><mrow><mi>b</mi><mi>c</mi><mover><mrow><mi>u</mi></mrow><mrow><mo>¯</mo></mrow></mover><mover><mrow><mi>d</mi></mrow><mrow><mo>¯</mo></mrow></mover></mrow></msub><mo>→</mo><msub><mrow><mi>T</mi></mrow><mrow><mi>c</mi><mi>c</mi><mover><mrow><mi>u</mi></mrow><mrow><mo>¯</mo></mrow></mover><mover><mrow><mi>d</mi></mrow><mrow><mo>¯</mo></mrow></mover></mrow></msub><mspace width="0.2em"></mspace><mo>(</mo><msup><mrow><mi>ℓ</mi></mrow><mrow><mo>−</mo></mrow></msup><msub><mrow><mi>ν</mi></mrow><mrow><mi>ℓ</mi></mrow></msub><mo>,</mo><mspace width="0.2em"></mspace><msup><mrow><mi>h</mi></mrow><mrow><mo>−</mo></mrow></msup><mo>)</mo></math>, where <math><msup><mrow><mi>h</mi></mrow><mrow><mo>−</mo></mrow></msup><mo>=</mo><msup><mrow><mi>π</mi></mrow><mrow><mo>−</mo></mrow></msup><mo>,</mo><msup><mrow><mi>ρ</mi></mrow><mrow><mo>−</mo></mrow></msup><mo>,</mo><msubsup><mrow><mi>a</mi></mrow><mrow><mn>1</mn></mrow><mrow><mo>−</mo></mrow></msubsup><mo>,</mo><msubsup><mrow><mi>D</mi></mrow><mrow><mi>s</mi></mrow><mrow><mo>−</mo></mrow></msubsup><mo>,</mo><msubsup><mrow><mi>D</mi></mrow><mrow><mi>s</mi></mrow><mrow><mo>⁎</mo><mo>−</mo></mrow></msubsup></math>. So far, only the <math><msup><mrow><mi>J</mi></mrow><mrow><mi>P</mi></mrow></msup><mo>=</mo><msup><mrow><mn>1</mn></mrow><mrow><mo>+</mo></mrow></msup></math> tetraquark <math><msub><mrow><mi>T</mi></mrow><mrow><mi>c</mi><mi>c</mi><mover><mrow><mi>u</mi></mrow><mrow><mo>¯</mo></mrow></mover><mover><mrow><mi>d</mi></mrow><mrow><mo>¯</mo></mrow></mover></mrow></msub></math> has been discovered, which we identify with the <math><mi>I</mi><mo>=</mo><mn>0</mn></math> <math><msubsup><mrow><mi>T</mi></mrow><mrow><mi>c</mi><mi>c</mi></mrow><mrow><mo>+</mo></mrow></msubsup></math> object, compatible with <math><msup><mrow><mi>J</mi></mrow><mrow><mi>P</mi></mrow></msup><mo>=</mo><msup><mrow><mn>1</mn></mrow><mrow><mo>+</mo></mrow></msup></math> and having the pole mass relative to the <math><msup><mrow><mi>D</mi></mrow><mrow><mo>⁎</mo><mo>+</mo></mrow></msup><msup><mrow><mi>D</mi></mrow><mrow><mn>0</mn></mrow></msup></math> mass threshold and decay widths <math><mi>δ</mi><mi>m</mi><mo>=</mo><mi>M</mi><mo>(</mo><msubsup><mrow><mi>T</mi></mrow><mrow><mi>c</mi><mi>c</mi></mrow><mrow><mo>+</mo></mrow></msubsup><mo>)</mo><mo>−</mo><mo>(</mo><mi>M</mi><mo>(</mo><msup><mrow><mi>D</mi></mrow><mrow><mo>⁎</mo><mo>+</mo></mrow></msup><mo>)</mo><mo>+</mo><mi>M</mi><mo>(</mo><msup><mrow><mi>D</mi></mrow><mrow><mn>0</mn></mrow></msup><mo>)</mo><mo>)</mo><mo>=</mo><mo>−</mo><mn>360</mn><mo>±</mo><msubsup><mrow><mn>40</mn></mrow><mrow><mo>−</mo><mn>0</mn></mrow><mrow><mo>+</mo><mn>4</mn></mrow></msubsup></math> keV and <math><mi>Γ</mi><mo>(</mo><msubsup><mrow><mi>T</mi></mrow><mrow><mi>c</mi><mi>c</mi></mrow><mrow><mo>+</mo></mrow></msubsup><mo>)</mo><mo>=</mo><msubsup><mrow><mn>48</mn></mrow><mrow><mo>−</mo><mn>14</mn></mrow><mrow><mo>+</mo><mn>2</mn></mrow></msubsup></math> keV. Experimental discoveries of the transitions worked out here, and related ones involving doubly-heavy baryons, will quantify the diquark-antidiquark component of these tetraquarks.

Germany

Ahmed Ali

Signature decay modes of the compact doubly-heavy tetraquarks And

Abstract Motivated by the study of heavy–light meson production within the framework of heavy quark effective theory (HQET) factorization, we extend the factorization formalism for a rather complicated process W$^{+}$ → B$^{+}$ℓ$^{+}$ℓ$^{−}$ in the limit of a nonzero invariant squared mass of the dilepton, q$^{2}$, at the lowest order in 1/m$_{b}$ up to . The purpose of the current study is to extend the HQET factorization formula for the W$^{+}$ → B$^{+}$ℓ$^{+}$ℓ$^{−}$ process and subsequently compute the form factors for this channel up to next-to-leading-order corrections in α$_{s}$. We explicitly show that the amplitude of the W$^{+}$ → B$^{+}$ℓ$^{+}$ℓ$^{−}$ process can also be factorized into a convolution between the perturbatively calculable hard-scattering kernel and the nonperturbative yet universal light-cone distribution amplitude (LCDA) defined in HQET. The validity of the HQET factorization depends on the assumed scale hierarchy m$_{W}$ ∼ m$_{b}$ ≫ Λ$_{QCD}$. Within the HQET framework, we evaluate the form factors associated with the W$^{+}$ → B$^{+}$ℓ$^{+}$ℓ$^{−}$ process, providing insights into its phenomenology. In addition, we also perform an exploratory phenomenological study on W$^{+}$ → B$^{+}$ℓ$^{+}$ℓ$^{−}$ by employing an exponential model for the LCDAs for the B$^{+}$ meson. Our findings reveal that the branching ratio for W$^{+}$ → B$^{+}$ℓ$^{+}$ℓ$^{−}$ is below 10$^{−10}$. Although the branching ratios are small, this channel in high-luminosity LHC experiments may serve to further constrain the value of λ$_{B}$.

Sajawal Zafar

Semileptonic Decay to the Meson with Lepton Pairs in Heavy Quark Effective Theory Factorization up to

Recently, the CMS and ATLAS collaborations have announced the results for H → Z[→ ℓ + ℓ − ]γ with ℓ = e or μ [1, 2], where H → Zγ is a sub-process of H → ℓ + ℓ − γ. This semi-leptonic Higgs decay gets both resonant and non-resonant contributions from the loop-induced H → Z[→ ℓ + ℓ − ]γ. To probe further features coming from these contributions to H → ℓ + ℓ − γ, we argue that the polarization of the final state leptons is also an important parameter. We show that the interference of resonant and non-resonant contributions, which is negligible in the case of unpolarized leptons, plays a significant role when considering the polarization of the final state lepton. For this purpose, we have calculated the polarized decay rates and the longitudinal (P L ), normal (P N ), and transverse (P T ) polarization asymmetries. We find that these asymmetries purely come from the loop contributions and are helpful to further investigate the resonant and non-resonant nature of H → Z[→ ℓ + ℓ − ]γ decay. We observe that for ℓ = e, μ, the longitudinal decay rate is highly suppressed around m ℓℓ ≈ 60 GeV when the final lepton spin is <math> <mo>−</mo> <mfrac> <mn>1</mn> <mn>2</mn> </mfrac> </math> $$ -\frac{1}{2} $$ , dramatically increasing the corresponding lepton polarization asymmetries. Furthermore, we analyze another observable, the ratio of decay rates <math> <msubsup> <mi>R</mi> <mrow> <mi>i</mi> <mo>±</mo> </mrow> <msup> <mi>ll</mi> <mo>′</mo> </msup> </msubsup> </math> $$ {R}_{i\pm}^{{\mathcal{ll}}^{\prime }} $$ , where ℓ and ℓ ′ refer to different final state lepton generations. Precise measurements of these observables at the HL-LHC and the planned e + e − collider can provide fertile ground to test not only the SM but also to examine the signatures of possible NP beyond the SM.

M. Junaid

A. Uzair

Analysis of final state lepton polarization-dependent observables in H → ℓ + ℓ − γ in the SM at loop level

The LHCb collaboration have recently updated their analysis of the resonant J/ 𝜓 p mass spectrum in the decay <math> <msubsup> <mi>Λ</mi> <mi>b</mi> <mn>0</mn> </msubsup> </math> $$ {\varLambda}_b^0 $$ → J/𝜓 p K − , making use of their combined Run 1 and Run 2 data. In the updated analysis, three narrow states, P c (4312)+, P c (4440)+, and P c (4457)+, are observed. The spin-parity assignments of these states are not yet known. We interpret these narrow resonances as compact hidden-charm diquark-diquark- antiquark pentaquarks. Using an effective Hamiltonian, based on constituent quarks and diquarks, we calculate the pentaquark mass spectrum for the complete SU (3) F lowest S- and P -wave multiplets, taking into account dominant spin-spin, spin-orbit, orbital and tensor interactions. The resulting spectrum is very rich and we work out the quark flavor compositions, masses, and J P quantum numbers of the pentaquarks. However, heavy quark symmetry restricts the observable states in Λ b -baryon, as well as in the decays of the other weakly-decaying b-baryons, Ξ b and Ω b . In addition, some of the pentaquark states are estimated to lie below the J/ 𝜓 p threshold in Λ b -decays (and corresponding thresholds in Ξ b - and Ω b -decays). They decay via c <math> <mover> <mi>c</mi> <mo>¯</mo> </mover> </math> $$ \overline{c} $$ annihilation into light hadrons or a dilepton pair, and are expected to be narrower than the P c -states observed. We anticipate their discovery, as well as of the other pentaquark states present in the spectrum at the LHC, and in the long-term future at a Tera-Z factory.

M. Aslam

Russia

Alexander Parkhomenko

Mass spectrum of the hidden-charm pentaquarks in the compact diquark model

The measurements of <math><mrow><msub><mrow><mi>R</mi></mrow><mrow><msup><mrow><mi>K</mi></mrow><mrow><mo>(</mo><mo>*</mo><mo>)</mo></mrow></msup></mrow></msub><mo>=</mo><mi>B</mi><mo>(</mo><mi>B</mi><mo>→</mo><msup><mrow><mi>K</mi></mrow><mrow><mo>(</mo><mo>*</mo><mo>)</mo></mrow></msup><msup><mrow><mi>μ</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>μ</mi></mrow><mrow><mo>−</mo></mrow></msup><mo>)</mo><mo>/</mo><mi>B</mi><mo>(</mo><mi>B</mi><mo>→</mo><msup><mrow><mi>K</mi></mrow><mrow><mo>(</mo><mo>*</mo><mo>)</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo></mrow></msup><mo>)</mo></mrow></math> in recent years have hinted lepton flavor nonuniversality and thus drawn widespread attentions. If these anomalies are induced by new physics (NP), deviations from the SM predictions may also be found in other channels via the same process at the quark level. In this work, we study in <math><mi>B</mi><mo>→</mo><msub><mi>K</mi><mn>1</mn></msub><mo>(</mo><mn>1270</mn><mo>,</mo><mn>1400</mn><mo>)</mo><msup><mi>μ</mi><mo>+</mo></msup><msup><mi>μ</mi><mo>−</mo></msup></math> decays the effects of two popular classes of NP models which can address the <math><mi>b</mi><mo>→</mo><mi>s</mi></math> anomalies, i.e., the leptoquark models and the <math><msup><mi>Z</mi><mo>′</mo></msup></math> models. By assuming that NP only affects the <math><mi>b</mi><mo>→</mo><mi>s</mi><msup><mi>μ</mi><mo>+</mo></msup><msup><mi>μ</mi><mo>−</mo></msup></math> transition, we find that the unpolarized and polarized lepton flavor universality (LFU) ratios <math><msub><mi>R</mi><mrow><msubsup><mi>K</mi><mn>1</mn><mrow><mo>(</mo><mi>L</mi><mo>,</mo><mi>T</mi><mo>)</mo></mrow></msubsup><mo>(</mo><mn>1270</mn><mo>)</mo></mrow></msub></math> are useful to distinguish among the NP models (scenarios) and the SM because they are sensitive to the NP effects and insensitive to the mixing angle <math><msub><mi>θ</mi><msub><mi>K</mi><mn>1</mn></msub></msub></math>, while the <math><msub><mi>R</mi><mrow><msubsup><mi>K</mi><mn>1</mn><mrow><mo>(</mo><mi>L</mi><mo>,</mo><mi>T</mi><mo>)</mo></mrow></msubsup><mo>(</mo><mn>1400</mn><mo>)</mo></mrow></msub></math> are sensitive to both NP and <math><msub><mi>θ</mi><msub><mi>K</mi><mn>1</mn></msub></msub></math>. Another ratio <math><mrow><msub><mi>R</mi><mi>μ</mi></msub><mo>(</mo><msub><mi>K</mi><mn>1</mn></msub><mo>)</mo><mo>=</mo><mi>B</mi><mo>(</mo><mi>B</mi><mo>→</mo><msub><mi>K</mi><mn>1</mn></msub><mo>(</mo><mn>1400</mn><mo>)</mo><msup><mi>μ</mi><mo>+</mo></msup><msup><mi>μ</mi><mo>−</mo></msup><mo>)</mo><mo>/</mo><mi>B</mi><mo>(</mo><mi>B</mi><mo>→</mo><msub><mi>K</mi><mn>1</mn></msub><mo>(</mo><mn>1270</mn><mo>)</mo><msup><mi>μ</mi><mo>+</mo></msup><msup><mi>μ</mi><mo>−</mo></msup><mo>)</mo></mrow></math> is shown to depend weekly on the effects from the NP models (scenarios) under consideration, and thus can be used to determine the <math><msub><mi>θ</mi><msub><mi>K</mi><mn>1</mn></msub></msub></math> and complement the <math><msub><mi>R</mi><msubsup><mi>K</mi><mn>1</mn><mrow><mo>(</mo><mi>L</mi><mo>,</mo><mi>T</mi><mo>)</mo></mrow></msubsup></msub></math> in the probe for NP.

China

Zhuo-Ran Huang

Muhammad Ali Paracha

Cai-Dian Lü

Testing leptoquark and <math><mrow><msup><mrow><mi>Z</mi></mrow><mrow><mo>′</mo></mrow></msup></mrow></math> models via <math><mi>B</mi><mo>→</mo><msub><mi>K</mi><mn>1</mn></msub><mo>(</mo><mn>1270</mn><mo>,</mo><mn>1400</mn><mo>)</mo><msup><mi>μ</mi><mo>+</mo></msup><msup><mi>μ</mi><mo>−</mo></msup></math> decays