Conveners
Flavor Physics and CP Violation
- Ying Li (Yantai University, China)
Flavor Physics and CP Violation
- Lorenzo Calibbi (Nankai University)
Flavor Physics and CP Violation
- Robert Ziegler (KIT - Karlsruhe Institute of Technology (DE))
Flavor Physics and CP Violation
- Ji-Bo He
Flavor Physics and CP Violation
- Yuming Wang (Nankai University)
Flavor Physics and CP Violation
- Lorenzo Calibbi (Nankai University)
Flavor Physics and CP Violation
- Lorenzo Calibbi (Nankai University)
Flavor Physics and CP Violation
- Ying Li (Yantai University, China)
Flavor Physics and CP Violation
- Robert Ziegler (KIT - Karlsruhe Institute of Technology (DE))
In the recent years, several measurements of $B$-decays with flavor changing neutral currents, i.e. $b\to s$ transitions hint at deviations from the Standard Model (SM) predictions. These decays are forbidden at tree-level in the SM and can only proceed via suppressed loop level or box diagrams. Rare decays of $B$ mesons are an ideal probe to search for phenomena beyond the SM, since...
We study the supersymmetric (SUSY) effects on $C_7(\mu_b)$ and $C'_7(\mu_b)$
which are the Wilson coefficients (WC) for $b \to s \gamma$ at b quark
mass scale $\mu_b$ and are closely related to radiative B meson decays.
The SUSY-loop contributions to $C_7(\mu_b)$ and $C'_7(\mu_b)$ are calculated
at leading order (LO) in the Minimal Supersymmetric Standard Model (MSSM) with
general...
Fermilab has just announced a new experimental result for muon g-2. The statistical uncertainty of the new result is similar to the previous BNL result and the central value is consistent. The combined value is now 4.2 standard deviation away from the Standard Model prediction. For the Standard Model prediction, the two hadronic contributions, HVP (hadronic vacuum polarization) and HLbL...
Hadronic vacuum polarization is a key ingredient of the SM prediction for g-2. However, it also enters the global EW fit, linking both of them. In this talk I discuss this interplay as well as the possible presence of NP in the EW fit and g-2.
We discuss a systematic classification of the models with the minimal field content to account for, at the same time, the g-2 anomaly, the ones emerging in decays of B-mesons and, finally, a viable thermal Dark Matter. We will illustrate, in some specific examples, the strong complementarity among flavor and Dark Matter observables.
Scenarios in which right-handed light Standard Model fermions couple to a new gauge group, $U(1)_{T3R}$ can naturally generate a sub-GeV dark matter candidate. But such models necessarily have large couplings to the Standard Model, generally yielding tight experimental constraints.
We show that the contributions to $g_\mu-2$ from the dark photon and dark Higgs largely cancel out in the narrow...
New light singlet scalars with flavor-specific couplings represent a phenomenologically distinctive and flavor-safe alternative to the well-studied possibility of Higgs-portal scalars. However, in contrast to the Higgs portal, flavor-specific couplings require an ultraviolet completion involving new heavy states charged under the Standard Model gauge symmetries, leading to a host of additional...
The confirmation of the discrepancy between the Muon g-2 experiment at Fermilab and the Standard Model prediction points to New Physics not far above the TeV scale. Flavour symmetries broken at low energies can account for it, although relevant constraints then arise from flavour-violating observables. Here I discuss the profound implications of this result over the structure of the...
The Minimal R-symmetric Supersymmetric Standard Model possesses interesting features, which makes it an attractive alternative to the MSSM. Some of them can be observed in and are reflected by the lepton flavour violation processes. Notably, there is no $\tan\beta$-enhancement for $g-2$ of the muon and other dipole operators, resulting in very different predictions for lepton observables...
We explore the implications of g-2 new result to five models based on the SU(3)C×SU(3)L×U(1)N gauge symmetry and put our conclusions into perspective with LHC bounds. We show that previous conclusions found in the context of such models change if there are more than one heavy particle running in the loop. Moreover, having in mind the projected precision aimed by the g-2 experiment at FERMILAB,...
The latest results of beauty and charm meson decays from LHCb are presented. This includes the latest time-integrated CP violation measurements with information on the (Kpi) puzzle and on the CKM angle gamma, and time-dependent CP violation measurements. In addition recent determinations of CKM elements, the legacy result on Bs mixing, and the first observation of the mass difference in the D0...
The decay K+→π+ νν ̅, with a very precisely predicted branching ratio of less than 10-10, is among the best processes to reveal indirect effects of new physics.
The NA62 experiment at CERN SPS is designed to study the K+→π+ νν ̅decay and to measure its branching ratio using a decay-in-flight technique. NA62 took data in 2016, 2017 and 2018, reaching the sensitivity of the Standard Model for...
A study of a sample of 4 109 tagged π0 mesons from K+→π+π0(γ) is performed at the NA62 experiment at CERN, searching for the decay of the π0 to invisible particles. No signal is observed in excess of the expected background fluctuations. An upper limit of 4.4 10−9 is set on the branching ratio at 90% C.L. improving on previous results by a factor of 60.
Rare $\vert \Delta c \vert=\vert \Delta u \vert=1$ processes constitute unique flavor probes in the up-sector of the Standard Model. Semileptonic FCNC decays of charmed baryons, such as $\Lambda_c\to p \mu^+\mu^-$, offer a large set of clean null test observables such as CP-asymmetries, lepton-universality ratios, missing energy modes, lepton flavor violating modes and angular observables. In...
The NA62 experiment at CERN collected a large sample of charged kaon decays into final states with multiple charged particles in 2016-2018. This sample provides sensitivities to rare decays with branching ratios as low as 10-11.
Results from searches for lepton flavour/number violating decays of the charged kaon and the neutral pion to final states containing a lepton pair based on this data...
The NA62 experiment at CERN reports new results from studies of radiative kaon decays K+ → pi0e+vg(Ke3g), using a data sample recorded in 2017-2018. The sample comprises O(100k) Ke3g candidates with sub-percent background contaminations. Preliminary results with the most precise measurement of the and branching ratios and T-asymmetry measurement in the Ke3g decay, are presented.
The lepton universality violating flavor ratios $R_K/R_{K^*}$ indicate new physics either in $b \to s \mu^+ \mu^-$ or in $b \to s e^+ e^-$ or in both. If the new physics is only $b \to s e^+ e^-$ transition, the corresponding new physics operators, in principle, can have any Lorentz structure. In this work, we perform a model independent analysis of new physics only in $b \to se^+e^-$ decay...
Lack of new states at the TeV scale challenges all kinds of solutions to the hierarchy problem but the current B anomalies might be a new guidance. One possible solution to the neutral current B anomalies is a TeV-scale $Z’$ boson of the broken $U(1)_F$ gauged flavor symmetry, which might implies the connection between the two problems. In this talk, I will realize this idea based on a...
The $3.1 \sigma$ $R_K$ anomaly after Moriond 2021 and $3.3 \sigma$ $\Delta a_\mu$ from Fermilab Muon g-2 Experiment implicate that the lepton flavor universality violation (LFUV) may play a role in the exploration of new physics. Aiming at solving these flavor anomalies both in quark and lepton sectors, a specific Two-Higgs Doublet Model (2HDM) with particular U(1) gauge symmetry, which is...
We present a compressive study on rare semileptonic $B_c \to D^{(*)}\tau \bar \nu_\tau$ decays involving $b \to u \tau \bar \nu_\tau$ quark level transitions in an effective field theory approach. We consider the presence of an additional (pseudo)vector and (pseudo)scalar type interactions which can be either complex or real and constrain the new couplings using the existing data on...
Though the Belle experiment has stopped data taking more than a decade ago, new results on $B$ meson decays are still being obtained. This is in part due to new experimental tools elaborated for Belle II applied to the Belle data set, such as the FEI (Full Event Interpretation) hadronic and semileptonic tag which enables new measurements of $B \to D^{*}\ell\nu$, $B \to D^{\ast\ast}\ell\nu$ and...
We present new physics implications of LHCb measurements of bsll observables within a model-independent approach and make projections for future measurements that indicate that LHCb will be in the position to discover lepton non-universality with the Run 3 data in a single observable. Moreover, we present global fits of rare B-decays within multidimensional fits involving up to all the...
We present potential signatures and combined constraints for leptoquarks which couple to first generation fermions, considering both low energy precision observables and LHC direct searches. Including all ten leptoquark representations, five scalar and five vector ones, we study at the precision frontier the constraints from $K\to\pi\nu\nu$, $K\to\pi e^+e^-$, $K^0-\bar K^0$ and $D^0-\bar D^0$...
Scalar Leptoquark models can explain the current anomalies in B physics. However, one of the main constraints on these models comes from Bs-mixing.
We analyse the QCD corrections to the Bs-mixing process within a scalar leptoquark model, going at 2-loop level. In order to examine the effect of this process we use a low energy EFT, and compute the Wilson coefficients at NLO.
The latest measurement of the ratio $R_K$ at LHCb provides evidence for lepton flavour non-universal interactions beyond the Standard Model.
A popular extension of the Standard Model is the R-parity conserving Minimal Supersymmetric Standard Model (MSSM), however, it is widely claimed in the literature that an explanation of these anomalies is not possible within this model.
In this talk, I...
We report on a new class of flavorful $Z^\prime$-extensions of the standard model, which explain the recent hints for lepton universality violation in $R_{K^{(*)}}$-data.
The models feature new vector-like fermions as well as additional scalar fields around the electroweak scale or above.
On top of well-known theoretical and phenomenological constraints, we require stable and Landau-pole...
The Randall Sundrum (RS) models receive significant constraints
from the neutral Kaon system. The CP violating observable $\epsilon_K$, in Randall Sundrum scenario, requires the lightest KK gluon to be heavier than $\sim$ 24 TeV. The constraint is even stronger in the Little Randall Sundrum models (LRS), $ \sim $ 32 TeV. The LRS models are motivated for their possible visibility at the...
We examine a common origin of four-dimensional flavor, CP, and $U(1)_R$ symmetries in the context of heterotic string theory with standard embedding. We find that flavor and $U(1)_R$ symmetries are unified into the $Sp(2h+2, \mathbb{C})$ modular symmetries of Calabi-Yau threefolds with $h$ being the number of moduli fields. Together with the $\mathbb{Z}_2^{\rm CP}$ CP symmetry, they are...
Clockwork models can explain the flavor hierarchies in the Standard Model quark and lepton spectrum.
We construct supersymmetric versions of such flavor clockwork models. The zero modes of the clockwork are identified with the fermions and sfermions of the Minimal Supersymmetric Standard Model. In addition to generating a hierarchical fermion spectrum, the clockwork also predicts a specific...
The flavour anomalies in the b->sll transition receive large attention.
Apart from the recent update on lepton-flavour-universality, LHCb has new results on the rare decay Bs->mumu, angular distributions of charged B mesons decaying to Kmumu and Phimumu, and analyses of radiative and B decays to Kee at low-q2, and most recently on the Bs->Phimumu decay rate with full run-2 data.
The first row of the Cabibbo-Cobayashi-Maskawa (CKM) matrix shows a discrepancy of ∼3$\sigma$ with unitarity, known as the ”Cabibbo Angle Anomaly” (CAA). After reviewing the origin and status of the anomaly, I investigate the various possibilities to explain it in the context of physics beyond Standard Model (BSM) which can be broadly grouped into three categories: modifications of...
The recent anomalies in $b\to s\ell^+\ell^-$ transitions could originate from some New Physics beyond the Standard Model. Either to confirm or to rule out this assumption, more tests of $b\to s\ell^+\ell^-$ transition are needed.
$\Lambda_b \to \Lambda \ell^+\ell^- $ decay provides us complimentary information of this mode in contrast to the mesonic decay. We will discuss how the polarized...
The ATLAS experiment has performed measurements of B-meson rare decays proceeding via suppressed electroweak flavour changing neutral currents, and of mixing and CP violation in the neutral Bs meson system.
This talk will focus on the latest results from the ATLAS collaboration, such as rare processes B^0_s → mu mu and B^0 → mu mu, and CP violation in the B_s^0 —> J/psi phi decays. In the...
Semileptonic flavor changing neutral current transitions with a pair of neutrinos in the final state are very accurately determined in the standard model. The most recent Belle II result on $B\to K \nu \bar{\nu}$ uses an innovative inclusive tagging technique; this together with previous BaBar and Belle results indicates a possible enhancement in the branching fraction of $B^+\to K^+ \nu...
To extract the Cabibbo-Kobayashi-Maskawa (CKM) matrix element $|V_{ub}|$, we have re-analyzed all the available inputs (data and theory) on the $b \to \pi l \nu$ decays including the newly available inputs on the form-factors from light cone sum rule (LCSR) and Lattice QCD (LQCD) approach. We have commented on the effect of outliers on the fits. After removing the outliers and creating a...
Motivated by the Xenon1T result, we study here a leptophilic flavor-dependent anomaly-free axionlike particle (ALP) and its effects on charged-lepton flavor violation. We present two representative models. The first one considers that the ALP origins from the flavon that generates the charged-lepton masses. The second model assumes a larger flavor symmetry such that more general mixings in the...
The flavour problem of the Standard Model can be addressed through the Froggatt-Nielsen (FN) mechanism. In this work, we develop an approach to the study of FN textures building a direct link between FN-charge assignments and the measured masses and mixing angles via unitary transformations in flavour space. We specifically focus on the quark sector to identify the most economic FN models able...
We analyse the sensitivity of quark flavour-changing observables to the MSSM, in a regime of heavy superpartners. We analyse four distinct and motivated frameworks characterising the structure of the soft-breaking terms by means of approximate flavour symmetries. We show that a set of six low-energy observables with realistic chances of improvement in the near future, namely $\Delta M_{s,d}ΔM...
Scenarios assuming an exact CP symmetry in the UV do not suffer quality problems, and are thus interesting alternatives to PQ-based solutions to the Strong CP problem. However, to correctly reproduce the Standard Model quark masses and CP violation these models must feature a non-trivial coincidence between a priori unrelated CP-even and CP-odd mass scales. In this talk we elucidate the origin...
