Description
Conveners:
Thomas Blake (University of Warwick)
Marzia Bordone (CERN)
Thibaud Humair (MPP)
Contact: eps23-conveners-t08 @desy.de
The entanglement in the neutral kaon pairs produced at the DA$\Phi$NE $\phi$-factory is a unique tool to test discrete symmetries. The exchange of in and out states required for a genuine test involving an antiunitary transformation implied by time-reversal is implemented exploiting the entanglement of ${K}^0\bar{K}{}^0$ pairs produced at a $\phi$-factory. We will present the final result of...
Novel quantum phenomena have been recently discussed [1] in association to a peculiar time correlation between entangled neutral kaons produced at a φ-factory: the past state of the first decayed kaon, when it was still entangled before its decay, is post-tagged by the result and the time of the future observation on the other kaon decay. This surprising “from future to past” effect is fully...
The NA62 experiment at CERN collected the world's largest dataset of charged kaon decays in 2016-2018, leading to the first measurement of the branching ratio of the ultra-rare $K^+ \rightarrow \pi^+ \nu \bar\nu$ decay, based on 20 candidates. In this talk the NA62 experiment reports recent results from analyses of $K^+ \rightarrow \pi^0 e^+ \nu \gamma$, $K^+ \rightarrow \pi^+ \mu^+ \mu^-$ and...
Rare kaon decays are among the most sensitive probes of both heavy and light new physics beyond the Standard Model description thanks to high precision of the Standard Model predictions, availability of very large datasets, and the relatively simple decay topologies. The NA62 experiment at CERN is a multi-purpose high-intensity kaon decay experiment, and carries out a broad rare-decay and...
We give a general prescription for the transformation between four-fermion effective operator bases via corrected Fierz identities at the one-loop level. The procedure has the major advantage of only relating physical operators between bases, eliminating the necessity for Fierz-evanescent operators, thereby reducing the number of operators which enter in higher-order EFT computations....
The Fermilab muon $g-2$ experiment was designed to measure the muon's anomalous magnetic moment $a_\mu=(𝑔−2)/2$ to 140 parts per billion. The value of $a_\mu$ is proportional to the difference frequency $\omega_a = \omega_s - \omega_c$ between the muon's cyclotron frequency and spin precession frequency in the uniform magnetic field of the $g-2$ storage ring. The frequency $\omega_a$ is...
The Muon g-2 experiment at Fermilab measures the muon magnetic-moment anomaly, $a_\mu=(g-2)/2$, with the ultimate goal of 140 parts per billion (ppb) precision. This requires determining the absolute magnetic field, averaged over space and time, experienced by the muons, expressed as the nuclear magnetic resonance frequency of protons in a spherical pure water sample at a specified reference...
The Muon g-2 experiment at Fermilab is making progress towards its physics goal of measuring the muon anomalous magnetic moment with the unprecedented precision of 140 parts per billion. In April 2021 the collaboration published the first measurement, based on the first year of data taking. The second result is based on the second and third years of data taking combined. In this talk, we...
During the last 15 years the "Radio MontecarLow (“Radiative Corrections and Monte Carlo Generators for Low Energies”) Working Group, see www.lnf.infn.it/wg/sighad/, has been providing valuable support to the development of radiative corrections and Monte Carlo (MC) generators for low energy e+e- data and tau-lepton decays. Its operation which started in 2006 proceeded until the last few years...
Systematic Operator Product Expansions can be applied to the hadronic light-by-light tensor in those kinematic regimes where there is any large external Euclidean momentum. In this talk it is reviewed how this can be applied to the different kinematic regimes entering into the muon g-2 integral, shedding some light on the interplay of short-distance and long-distance contributions in the...
Charged lepton flavor violation (CLFV) is forbidden in the Standard Model but possible in several new physics scenarios. Thus, the observation of CLFV would be a clear signature of new physics. We report the world-leading result of lepton-flavor-violating decays of \tau lepton decays into a light charged lepton ($\ell$ = e, $\mu$) and a vector meson using the full data sample collected by the...
The CPT symmetry is one of the most fundamental symmetries in physics. Any violation of this symmetry would have profound implications for our understanding of the universe [1]. In this study, we report the CPT symmetry tests in 3$\gamma$ decays of polarised $^3$S$_{1}$ positronium using the Jagiellonian Positron Emission Tomography device. The J-PET experiment allows sensitive and precise...
he MEG II experiment, which focuses on investigating Charged Lepton Flavour Violation in muon decays, completed the commissioning of all subdetectors in time for the 2021 run. Recently, it concluded the second year of data collection at the Paul Scherrer Institut (CH).
The experimental apparatus has been specifically designed to search for $\mu^+ \rightarrow e^+ \gamma$ decays, aiming for a...
The tree-level determination of the CKM angle gamma is a standard candle measurement of CP violation in the Standard Model. The latest LHCb results from time-integrated measurements of CP violation using beauty to open charm decays are presented. These include updates to previous Run 1 measurements using the full LHCb Run 1+2 data sample and the latest LHCb gamma & charm mixing combination.
This talk will summarize the latest results on branching fractions and CP violation in the B->DX family of decays.
In this work, we investigate the time-dependent angular analysis of $B_s^0 \rightarrow \phi \phi$ decay to search for new physics signals via CP-violating observables. We work with a new physics Hamiltonian containing both left- and right-handed Chromomagnetic dipole operators. The hierarchy of the helicity amplitudes in this model gives us a new scheme of experimental search, which is...
The study of CP violation in charmless B decays is of great interest as penguin and tree-level topologies contribute to the decay amplitudes with comparable strengths. The former topologies may be sensible to new particles appearing in the loops as virtual contributions. However the interpretation of physics quantities in terms of CKM parameters is not trivial due to strong-interaction effects...
The investigation of $B$-meson decays into charmed and charmless hadronic final states is a keystone of the Belle II program. It offers theoretically reliable and experimentally precise constraints on CKM unitarity, it is sensitive to effects from non-SM physics, and it furthers knowledge about uncharted $b \to c$ hadronic transitions. Recent results on branching ratios and direct CP-violating...
Nowadays little is know about the dynamics behind the decays of heavy flavoured particles into final states with baryons. The description of these decays is very challenging from the theoretical point of view and more experimental results are fundamental to shed light on the particular features of these decays, like the enhancement close to the p-pbar threshold in multibody decays, or the...
Time-dependent measurements of CP violation are chief goals of the Belle II physics program. Comparison between penguin-dominated $b \to q\bar qs$ and tree-dominated $b \to c \bar cs$ results allows for stringent tests of CKM unitarity that are sensitive to non-SM physics. This talk presents recent Belle II results on $B^0 \to K_S \pi^0$, $B^0 \to K_S K_S K_S$, and $B^0 \to \phi K_S$ decays.
Measuring the mixing phases of the B0 and Bs mesons is very important to validate the CP violation paradigm of the Standard Model and to search for new physics beyond it. Golden modes to measure these quantities are those governed by tree-level $b\to c\bar{c}q$ transitions, that allow precise and theoretically clean determinations to be performed. Besides, measuring the mixing phases with...
Flavour physics represents a unique test bench for the Standard Model (SM). New analyses performed at the LHC experiments and new results coming from Belle II are bringing unprecedented insights into CKM metrology and new results for rare decays.
The CKM picture provides very precise SM predictions through global analyses. We present here the results of the latest global SM analysis performed...
The usual unitarity triangles of either the $3\times 3$ CKM quark flavor mixing matrix or the $3\times 3$ PMNS lepton flavor mixing matrix are not fully rephasing-invariant, although their areas are all equal to a half of the corresponding Jarlskog invariant of CP violation. Here we propose the novel "rescaled unitarity triangles" (RUTs), whose sides are completely rephasing-invariant and...
Charm physics, involving a heavy up-type quark, offers a pathway to search for new particles and couplings beyond the Standard Model complementary to that of B physics. A program based on precision measurements of charm lifetimes is now underway at Belle II, and benefits from the detector's outstanding vertexing performance and low-background environment. Recent results from measurements of...
A systematic treatment of electromagnetic and strong corrections to the semi-leptonic decays is needed in order to have a precise determination of phenomenological parameters of the Standard Model (SM), such as CKM matrix elements. Under the presence of QED, the matrix element associated to the effective semi-leptonic operator on the lattice has to be renormalised, thus requiring a matching to...
We present updated predictions of $R(D^{(*)})$ using a modified power-counting within the heavy quark effective theory that results in a highly constrained set of second-order power corrections in the heavy quark expansion, compared to the nominal expansion. We analyze new experimental data to determine all $B \to D^{(*)}$ form factors within and beyond the Standard Model at...
Semileptonic $B$-meson decays allow for determining the magnitudes of the CKM matrix parameters $|V_{cb}|$ and $|V_{ub}|$, two fundamental parameters of the SM flavor sector. Belle II analyses use both exclusive decays such as $B \to D^*\ell \nu$ and $B \to \pi \ell \nu$, or inclusive $X_c \ell \nu$ or $X_u \ell \nu$ final states restricted in phase space. The low-background collision...
We report the measurement of the partial branching fraction of $B \to X_u \ell \bar \nu_\ell$ over $B \to X_c \ell \bar \nu_\ell$ using the complete Belle data set of 711 fb${}^{-1}$. We reconstruct collision events where one B meson is fully reconstructed in hadronic modes using the full-event-interpretation algorithm, developed for Belle II. This allows for the reconstruction of the hadronic...
Semileptonic $b$-hadron decays proceed via charged-current interactions and provide powerful probes for testing the Standard Model and for searching for New Physics effects. The advantages of studying such decays include the large branching fractions and reliable calculations of the hadron matrix elements. In this contribution, LHCb measurements on CKM paramenters and test of new physics will...
We present a new measurement of the lepton-flavor-universality ratios $R(D^{(*)})$ utilizing the entire Belle data set, which corresponds to an integrated luminosity of 711 fb${}^{-1}$. The analysis employs hadronic tag-side reconstruction, leveraging the capabilities of the full-event-interpretation algorithm developed for Belle II. This results in a significant efficiency improvement of...
The observed rate of semitauonic $B$ decays has been consistently above expectations since these decays were first measured. Significant differences between the forward-backward asymmetry in $B \to D^*e \nu$ and $B \to D^* \mu \nu$ were also reported. Belle II data are well suited to probe these anomalies. The low-background collision environment along with the possibility of partially or...
In the last ~10 years, several discrepancies, at the level of several standard deviations, between flavor observables and the SM predictions have been found by the Belle, BaBaR, and LHCb collaborations. In this talk, the results from the CMS experiment on these flavor anomalies are presented. The results are based on 13 TeV pp collision data collected during 2016-2018.
The rare $B \to K^{(*)} \bar{\ell} \ell$ decays exhibit a long-standing tension with Standard Model (SM) predictions, which can be attributed to a lepton-universal short-distance $b \to s \bar{\ell} \ell$ interaction. We present two novel methods to disentangle this effect from long-distance dynamics: one based on the determination of the inclusive $b \to s \bar{\ell} \ell$ rate at high...
The idea of partial compositeness (PC) in Composite Higgs models offers an attractive means to explain the flavor hierarchies observed in nature. In this talk, predictions of a minimal UV realization of PC, considering each Standard-Model (SM) fermion to mix linearly with a bound state consisting of a new scalar and a new fermion, are presented, taking into account the dynamical emergence of...
Rare B-hadron decays mediated by b-> sll transitions provide a sensitive test of Lepton Flavour Universality (LFU), a symmetry of the Standard Model by which the coupling of the electroweak gauge bosons to leptons is flavour universal. Extensions of the SM do not necessarily preserve this symmetry and may give sizable contributions to these processes. Precise measurements of LFU ratios are,...
Rare B decays at LHCb, such as those mediated via $b \to s\mu\mu$ transitions, offer sensitivity to heavy New Physics particles. Over the last decade, a pattern of tensions between measured $b \to s\mu\mu$ decays and their Standard Model predictions have emerged. These tensions appear in both branching fraction ratios and angular analyses. This talk will give an overview of recent $b \to...
Recent CMS results on rare decays with FCNC transition b-->sll are reported. The analyses are based on proton-proton collision data collected in pp collisions at sqrt(s)=13 TeV.
Decays of B mesons that proceed through radiative penguin amplitudes probe a large class of generic non-SM models for which Belle II has unique reach. We present recent results from an inclusive $b \to s \gamma$ analysis and a $B \to \rho \gamma$ analysis. In addition, we report results on $b \to s \ell^+ \ell^-$ decays of B mesons, which proceed through electroweak penguin amplitudes and...
Baryon asymmetry of the Universe (BAU) provides unambiguous evidence for need of New Physics (NP). In this context, a general two Higgs doublet model (g2HDM) without $Z_2$ symmetry is appealing because it can solve BAU via electroweak baryogenesis (EWBG), while the scenario can be tested in direct searches as well as in low energy precision measurements of flavor observables. We discuss...
We analyze the implications of current $b \to s \ell \ell$ ($\ell=e, \, \mu$) measurements on several $B \to K^* \tau^+ \tau^-$ observables under the assumption that the possible new physics can have both universal as well as nonuniversal couplings to leptons. For these new physics solutions, we intend to identify observables with large deviations from the Standard Model (SM) predictions as...
Physics of the up-type flavour offers unique possibilities of testing the Standard Model (SM) compared to the down-type flavour sector. Here, I discuss SM and New Physics (NP) contributions to the rare $D$-meson decays $ D^0 \to \pi^+ \pi^- \ell^+ \ell^- $. In particular, I discuss the effect of including the lightest scalar isoscalar resonance in the SM picture, namely, the $f_0 (500)$. Other...
We update our analysis of D meson mixing including the combined analysis of B and D decays. We derive constraints on absorptive and dispersive CP violation by combining all available data. We also provide posterior distributions for observable parameters appearing in D physics, as well as for the CKM phase gamma.
Measuring the total charm cross section is important for the comparison to theoretical predictions with the highest precision available today, which are
completely known up to NNLO in perturbative QCD for the total inclusive
charm cross sections in pp collisions, while they are only known up to NLO+NLL for
differential and fiducial cross sections. All total charm cross-section...
We propose new methods to determine the $\Upsilon(4S)\to B^+B^-$ and $\Upsilon(4S)\to B^0\overline B^0$ decay rates. These rates and their ratio are some of the limiting uncertainties in absolute branching fraction measurements, and thereby for a variety of applications, such as flavor symmetry relations. The new methods we propose are based in one case on exploiting the $\Upsilon(5S)$ data...
The Future Circular Collider (FCC) is a post-LHC project aiming at direct and indirect searches for physics beyond the SM in a new 91 km tunnel at CERN. The abundant production of beauty and charm hadrons in the $8\times 10^{12}$ Z boson decays expected in e+e- collisions at FCC-ee offers outstanding opportunities in flavour physics with b and c hadron samples that exceed those available at...
We analyze the implications of current $b \to s \ell \ell$ ($\ell=e, \, \mu$) measurements on several $B \to K^* \tau^+ \tau^-$ observables under the assumption that the possible new physics can have both universal as well as nonuniversal couplings to leptons. For these new physics solutions, we intend to identify observables with large deviations from the Standard Model (SM) predictions as...
