Conveners
Flavour Physics and CP Violation
- Angela Papa
- Mitesh Patel (Imperial College (GB))
- Admir Greljo
Flavour Physics and CP Violation
- Angela Papa
- Admir Greljo
- Mitesh Patel (Imperial College (GB))
Flavour Physics and CP Violation
- Mitesh Patel (Imperial College (GB))
- Admir Greljo
- Angela Papa
Flavour Physics and CP Violation
- Admir Greljo
- Angela Papa
- Mitesh Patel (Imperial College (GB))
Flavour Physics and CP Violation
- Angela Papa
- Mitesh Patel (Imperial College (GB))
- Admir Greljo
The Belle II experiment at the SuperKEKB energy-asymmetric $e^+ e^-$ collider is a substantial upgrade of the B factory facility at the Japanese KEK laboratory. The design luminosity of the machine is $8\times 10^{35}$ cm$^{-2}$s$^{-1}$ and the Belle II experiment aims to record 50 ab$^{-1}$ of data, a factor of 50 more than its predecessor. From February to July 2018, the machine has...
Decays of the Bs meson via b->ccbars transitions are excellent probes for physics beyond the Standard Model due to their sensitivity to the CP-violating phase phi_s. In addition, the Bs decay width and the decay width difference between the Bs mass eigenstates are measured precisely in these modes. We present the first Run 2 measurements of these quantities at LHCb.
In the Standard Model of particle physics, CP violation arises due to a single complex phase in the CabibboโKobayashiโMaskawa (CKM) quark mixing matrix. Testing the validity of the CKM mechanism as the only source of CP violation is one of the major experimental challenges in particle physics today. Precise measurement of the CKM parameters therefore constrains the Standard Model, and may...
B meson decays with contributions from loop processes give access to physics within and beyond the Standard Model through measurements of their CP-violating parameters and branching fractions. We present the latest LHCb results of direct CP violation searches in B meson decays using a two-body approximation.
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, and new results from processes that have never been studied before, using the LHCb Run 2 data sample.
We present the first model-independent measurement of the CKM angle $\phi_3$ using $B^{\pm}\to D(K_{\rm S}^0\pi^+\pi^-\pi^0)K^{\pm}$ decays. The GGSZ method is used by binning the a five-dimensional phase space of the $D$ decay. This analysis uses the measurement of the average strong-phase differences across the phase space in $D \to K_{\rm S}^0\pi^+\pi^-\pi^0$ decays from CLEO-c, as input....
The latest time-dependent CP violation measurements using beauty to open charm decays from LHCb are presented. These decays provide sensitivity to important CKM parameters such as the angles beta and gamma from the unitarity triangle. Measurements include the latest results from new decay channels, analysed for the first time, including data from both LHCb Run 1 and Run 2.
In the B meson sector, measurements of weak phases not associated with Vub are obtained through time-dependent, flavour-tagged analyses involving B-Bbar mixing. In addition to new phases that may enter the mixing loop, charmless B decays have an additional mechanism for unknown particles to induce deviations from the Standard Model expectation due to the sizeable contribution to these decays...
Very large CP asymmetries in decays of B mesons to final states containing three charged particles have been observed and attracted much interest. We present new results from a Dalitz plot analysis of B -> 3pi using a data sample corresponding to an integrated luminosity of 3 fb-1 of pp collisions recorded by the LHCb detector. Significant CP violation from different sources (S-wave,...
Long-distance resonant dynamics along with a sizeable weak phase present in multi-body charmless b-hadron decays leads to a rich structure of CP violation as a function of the phase space. Amplitude analysis provides a deeper understanding of the mechanisms that generate strong phase variations, which are responsible for this effect. We present the amplitude analyses of B+ -> pi+ K+ K- and Bs...
Using the entire Belle dataset collected at the Upsilon(4S) resonance containing 772 million B-meson pairs, measurements of time-dependent CP violation in neutral B meson decays are performed for the decay channels governed by, or sensitive to, the b โ s penguin (loop) transitions. In this presentation, we report a new measurement of CP violation parameters in B โ Ks Ks Ks and few other channels.
The associated production of vector boson with quarkonia is a key observable for understanding the quarkonium production mechanisms, including the separation of single and double parton scattering components.
This talk will present the latest measurements from ATLAS on quarkonium production, including associated production.
The Belle II experiment at the SuperKEKB energy-asymmetric $e^+ e^-$ collider is a substantial upgrade of the B factory facility at the Japanese KEK laboratory. The design luminosity of the machine is $8\times 10^{35}$ cm$^{-2}$s$^{-1}$ and the Belle II experiment aims to record 50 ab$^{-1}$ of data, a factor of 50 more than its predecessor. With this data set, Belle II will be able to measure...
Recently LHCb announced the exciting discovery of direct CP asymmetry in D0 decays to K-pairs and pion pairs around 15X10^-4. It is extremely difficult to do reliable calculations for the expectations from the SM for these asymmetries because of large non-perturbative effects. However, a novel mechanism is proposed to helps us understand roughly the size of the asymmetry and the key idea...
LHCb is playing a crucial role in the study of rare and forbidden decays of charm hadrons, which are sensitive to effects beyond the Standard Model. New searches for FCNC-mediated processes and asymmetry measurements in multibody final states with two leptons are presented.
Flavor-changing neutral current (FCNC) processes are rare within the Standard Model (SM) as they cannot occur at tree level and are suppressed at loop level by the Glashow-Iliopoulos-Maiani (GIM) mechanism. In $D$-meson decays, the GIM cancellation is almost exact, leading to expected branching fractions for $c\to u l^- l^+$ processes of order $\mathcal{O}(10^{-9})$. However, long-distance...
The large sample of charmed hadrons collected by LHCb is used to measure D0โD0bar mixing and to search for indirect CP violation as well as to measure direct CP violation in D0 mesons and Lambda_c+ baryons. New measurements from several decay modes are presented, including the first observation of CP violation in the charm system. We also discuss prospects for future sensitivities.
The KLOE-2 experiment at the Frascati Laboratories of INFN
collected at the DA$\Phi$NE collider an integrated luminosity of 5.5 fb$^{-1}$ that
together with the 2.5 fb$^{-1}$ collected by its predecessor KLOE corresponds
to $\sim 8 \times 10^{9}$ $K_SK_L$ entangled pairs produced.
This is the world largest available data sample of this typology and represents a unique tool
to improve the...
The recent release of improved lattice data has revived again the interest on precise theoretical predictions for the direct CP-violation ratio $\varepsilon'/\varepsilon$. We present a complete update of the Standard Model prediction, including a new re-analysis of isospin-breaking corrections which are of vital importance in the theoretical determination of this observable. Contrary to recent...
The decay K+โฯ+๐ฃ๐ฃฬ , with a very precisely predicted branching ratio of less than 10-10, is one of the best candidates to reveal indirect effects of new physics at the highest mass scales. The NA62 experiment at the CERN SPS is designed to measure the branching ratio of the K+โฯ+๐ฃ๐ฃฬ with a decay-in-flight technique. NA62 took data so far in 2016-2018. Statistics collected in 2016 allowed NA62...
The NA62 experiment at CERN collected a large sample of charged kaon decays into final states with multiple charged particles in 2016-2018. The sensitivity to a range of lepton flavour and lepton number violating kaon decays provided by this data set improves over the previously reported measurements. Results from the searches for these processes with a partial NA62 data sample are presented.
The NA48/2 experiment at CERN reports the first observation of the Kยฑ โ ฯยฑฯ0e eโ decay from an exposure of 1.7ร1011 charged kaon decays recorded in 2003โ2004. A sample of 4919 candidates with 4.9% background contamination allows the determination of the branching ratio in the full kinematic region. The study of the kinematic space shows evidence for a structure dependent contribution in...
We assume that the quark-flavor coefficients matrix of the semileptonic operators addressing the neutral-current B-meson anomalies has rank-one, i.e. it can be described by a single vector in quark-flavor space. By correlating the observed anomalies to other flavor and high-pT observables, we constrain its possible directions and we show that a large region of the parameter space of this...
b-hadron decays proceeding via charged-current interactions are excellent tools to study the CKM matrix, b-hadron properties, hadronic form-factors and Lepton Universality. The large branching fractions, coupled with excellent particle identification capability and accurate reconstruction of decay vertices, enable the LHCb experiment to perform high-precision measurements of many key...
The magnitudes of the Cabibbo-Kobayashi-Maskawa (CKM) matrix elements, in combination with the angles of the Unitarity Triangle, are crucial for testing the standard model. We report a new determination of $|V_{cb}|$ based on $B \to D^* l^+ \nu$ decays in untagged events. Different parameterizations of the semileptonic form factor are used in the extraction of this CKM matrix element. Finally,...
The Belle II experiment at the SuperKEKB energy-asymmetric $e^+ e^-$ collider is a substantial upgrade of the B factory facility at the Japanese KEK laboratory. The design luminosity of the machine is $8\times 10^{35}$ cm$^{-2}$s$^{-1}$ and the Belle II experiment aims to record 50 ab$^{-1}$ of data, a factor of 50 more than its predecessor. From February to July 2018, the machine has...
We present results on the first full 4-dimensional angular analysis of $B\to D^{(*)} l \nu$, using the $e^+e^-$ collision dataset collected by the $BABAR$ experiment at the $\Upsilon(4S)$ resonance. One $B$ meson from the $\Upsilon(4S)\to B\bar{B}$ decay is fully reconstructed in a hadronic decay mode which constrains the kinematics and provides a precise determination of the neutrino momentum...
We present new precision predictions for semitauonic decays involving rho and omega final state mesons. These decay channels offer an interesting orthogonal probe to study the existing B anomalies in semitauonic transitions and are accessible with the Belle II experiment. The predictions are based on combining existing light-cone sum-rule calculations for the form factors with measured...
Recent theory results for the full set of hadronic matrix elements arising in $B\to D^{(*)}\ell\nu$ decays have triggered our interest. We investigate if and how various pieces of theory information on these hadronic matrix elements fit together. As a consequence, we obtain precise theory predictions for the full angular distribution of these decays in the SM and beyond. Finally, we challenge...
The search for new physics (NP) involving semileptonic $b$-hadron decays requires large, dedicated Monte Carlo data sets, in order to properly model acceptance and selection efficiencies. We present the Hammer reweighting tool, developed for and in conjunction with the LHCb and Belle II experiments, that makes use of an efficient event and histogram reweighting strategy, permitting...
The precision determination of the CKM matrix element $|V_{cb}|$ from
semileptonic $B \to D^*$ and $B \to D$ decays provides an important input to test
the unitarity of the CKM matrix and search for new physics. In recent
analyses, higher values of $|V_{cb}|$ were extracted using (the so-called BGL)
form factor parametrization, which allows more freedom to describe the
experimental...
The heavy quark effective theory makes model independent
predictions for semileptonic $\Lambda_b$ baryon decays in terms of a small
set of parameters. No subleading Isgur-Wise function occurs at order
$\Lambda_{QCD}/m_{c,b}$, and only two sub-subleading functions enter at order
$\left(\Lambda_{QCD}/m_{c}\right)^2$. These features allow us to fit the form factors and decay
rates calculated...
We perform a general model-independent analysis of $b \to c \tau \bar{\nu}_\tau $ transitions, including measurements of $\mathcal{R}_D$, $\mathcal{R}_{D^*}$, their $q^2$ differential distributions, the recently measured longitudinal $D^*$ polarization $F_L^{D^*}$, and constraints on the $B_c \to \tau \bar{\nu}_\tau$ lifetime. A global fit to a general set of Wilson coefficients of an...
Rare b->sll decays are flavour changing neutral current processes that are forbidden at the lowest perturbative order in the Standard Model (SM). As a consequence, new particles in SM extensions can significantly affect the branching fractions of these decays and their angular distributions. Particularly interesting are extensions of the SM that violate lepton flavour universality. Since rare...
Recent anomalies of lepton flavor universality violation (LFUV) in B decays could be a hint of new physics. We report new measurements of LFUV observable R(K) and R(K*), the branching fraction of $B \to K^{(*)} \mu^+ \mu^-$ to $B \to K^{(*)} e^+ e^-$, at Belle. The analyses are based on the full data set recorded by the Belle detector at the $\Upsilon(4S)$ resonance containing 772 million...
Recent results in the searches for rare processes involving B-mesons are presented. Particular attention will be given to FCNC processes, such as the decay of Bs and Bd into two muons, and the angular analysis of the decay of Bd -> K* mu mu, where a number of angular coefficients are measured as a function of the invariant mass squared of the di-muon system. Comparison is made to theoretical...
We report new results on rare decays involving heavy flavors and tau leptons, using pp collision data collected by the CMS experiment at the LHC during the Run 2. The most recent measurements of angular variables in B -> K(*)mm decays are also presented.
In this talk recent results from LHCb on radiative and very rare decays at LHCb are presented.
Radiative b-hadron decays are sensitive probes of New Physics through the study of branching fractions, CP asymmetries and measurements of the polarisation of the photon emitted in the decay. During Run-1 of the LHC, the LHCb experiment has collected large samples of radiative b-hadron decays. The...
Recent hints for lepton-universality violation in b->sll transitions could imply the existence of lepton-flavour violating B decays. The LHCb experiment is well suited for the search for these decays due to its large acceptance and trigger efficiency, as well as its excellent invariant mass resolution and particle identification capabilities. Recent results on searches for lepton-flavour...
Flavor violating decay of muon is a good probe of new physics beyond SM. Many well motivated new physics models predict $\mu \to e\gamma$ decay to occur at large branching ratio (e.g. $O(10^{-14}$) in SUSY-seesaw). MEG II experiment will search for $\mu \to e \gamma$ decay with target sensitivity down to $6\times 10^{-14}$, which is an order of magnitude better than the sensitivity of MEG....
The Mu3e experiment searches for the charged lepton flavour violating ๐+ โ ๐ฆ+ ๐ฆ+ ๐ฆ- decay and it aims at reaching an ultimate sensitivity of 10^{-16} on the branching fraction of the ๐+ โ ๐ฆ+ ๐ฆ+ ๐ฆ- decay, four orders of magnitude better than the current limit B(๐+ โ ๐ฆ+ ๐ฆ+ ๐ฆ-)<10^{-12} set by the SINDRUM experiment. The experiment will be hosted at the Paul Scherrer Institute (Villigen,...
The COMET experiment is designed to search for a muon to electron ($\mu$-$e$) conversion without associating neutrinos, where the lepton flavour is violated at the charged lepton sector, with unprecedented sensitivity. The charged lepton flavour violating processes (CLFV) are forbidden in the Standard Model, while many plausible models beyond the SM (BSM) predict the detectable rates of CLFV...
The Mu2e experiment aims to measure the charged-lepton flavor violating (CLFV) neutrino-less conversion of a negative muon into an electron in the field of a nucleus. The coherent conversion process results in a monochromatic electron with an energy slightly below the muon rest mass (104.97 MeV). The goal of the experiment is to improve the previous measurement by four orders of magnitude ...
Dipole operators encode a rich variety of phenomena, such as radiative decays and electric dipole moments in both quark and lepton sectors, which probe physics beyond the Standard Model up to very high energy scales. Through renormalization, non-dipole operators mix into dipole ones, thus possibly generating observable effects that can be investigated by those same phenomena. I will discuss...
We revisit the calculation of nonfactorizable corrections induced by charm-quark loops in exclusive FCNC $B$-decays. We demonstrate that the calculation of the corresponding correlation function requires the knowledge of the full generic three-particle quark-antiquark-gluon distribution amplitude of the B-meson with non-aligned arguments, $\langle 0| \bar q(x) G_{\mu\nu}(y)b(0)|B\rangle$. The...
We present a method to find anomaly-free gauged U(1) Froggatt-Nielsen type models using results from algebraic geometry. These methods should be of general interest for model building beyond the Standard Model when rational charges are required. We consider models with a gauged U(1) flavour symmetry with one flavon and provide several model examples based on different physical assumptions. The...
I present a viable two leptoquark model based on $SU(5)$ gauge symmetry that addresses the $B$-physics anomalies. The entire low-energy flavor structure of the set-up originates from two $SU(5)$ operators that relate Yukawa couplings of the two leptoquarks. The proposed scenario accommodates all measured lepton flavor universality ratios in $B$-meson decays, is consistent with related flavor...
I will present an improved parametrisation of the contribution of $\bar c c$ real intermediate states in the $B^+ \to K^+ \mu^- \mu^+$ decay,
aimed at improving the description of the dilepton spectrum and, possibly, the extraction of short-distance information from this process. Motivated by B-anomalies,
whose combined explanations calls for large NP in the $b \to s \tau^{-} \tau^{+}$...
Recent experimental measurements hint for possible new physics effects in B-meson decays, the so-called B-anomalies. New physics explanations of the anomalies generically imply large effects also in other observables, both at low-energies and at high-pT. I will review new physics scenarios able to address these anomalies and discuss their smoking-gun signatures. The possible connection of...
We revisit soft gluon contributions to the "charm loop" effect in rare $B\to K^{(*)}ll$ decays, which is a large systematic uncertainty in the interpretation of the b-anomalies. Since these contributions are dominated by long-distance effects and are resistant to factorization attempts, we employ the method of light-cone sum rules to compute the relevant hadronic matrix elements. Our...
We present a Bayesian analysis of the implications for new physics in semileptonic $b\to s$ transitions after including new measurements of $R_K$ at LHCb and new determinations of $R_{K^*}$ and $R_{K^{*+}}$ at Belle. We perform global fits with 1, 2, 4, and 8 input Wilson coefficients, plus one CKM nuisance parameter to take into account uncertainties that are not factorizable. We infer the...
We investigate the possibility of accounting for the $b\to s\ell^+\ell^-$ anomalies via box contributions involving with new scalars and fermions.For this purpose we extend previous analysis by allowing that the new particles can also couple to right-handed Standard Model (SM) fermions as preferred by recent $b\to s\ell^+\ell^-$ data and the anomalous magnetic moment of the muon.
In the...
We report the measurements of the branching fractions of the decays $\tau \to K\,n\pi^0 \nu$, $n=0,1,2,3$, and $\tau\to \pi\, n\pi^0 \nu$, $n=3,4$. The measurements are based on a data sample of 435 million tau pairs produced in $e^+e^-$ collisions at and near the $Y(4S)$ peak and collected with the BABAR detector in $1999-2008$. Additional systematic studies have been completed after the...
We present improved determinations of |Vus| with tau decays relying on the HFLAV tau branching fractions global fit results. The HFLAV results are to be included in the 2019 HFLAV report and use the recent new BaBar measurements of:
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the branching fractions of the processes $\tau^{-}\to K^{-} n\pi^{0}\nu_\tau$ with n=1,2,3 and $\tau^{-}\to \pi^{-} n\pi^{0}\nu_\tau$ with n=3,4;
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the...
