Conveners
Quark and Lepton Flavor Physics: BSM Flavor Model
- Yousen Zhang (Brookhaven National Laboratory)
Quark and Lepton Flavor Physics: Techniques and Algorithms
- Gianantonio Pezzullo (Yale University)
Quark and Lepton Flavor Physics: B decays
- Joachim Brod (University of Cincinnati)
Quark and Lepton Flavor Physics: Anomalies and Top Physics
- Xing Wang (UC San Diego)
Since the landmark discovery in 2012 of the h(125) Higgs boson at the LHC, it should be a nobrainer to pursue the existence of a second Higgs doublet. We advocate, however, the general 2HDM
(g2HDM) that possesses a second set of Yukawa couplings. The extra top Yukawa coupling ฯtt drives
electroweak baryogenesis (EWBG), i.e. generating Baryon Asymmetry of the Universe (B.A.U.) with...
Baryon number violation is our most sensitive probe of physics beyond the Standard Model, especially through the study of nucleon decays. Angular momentum conservation requires a lepton in the final state of such decays, kinematically restricted to electrons, muons, or neutrinos. We show that operators involving tauons, which are at first sight too heavy to play a role in nucleon decays, still...
The fermion mass hierarchy of the Standard Model (SM) spans many orders of magnitude and begs for a further explanation. The Froggatt-Nielsen (FN) mechanism is a popular solution which introduces an additional $U(1)$ symmetry to the SM under which SM fermions are charged. We studied the general class of FN solutions to the lepton flavor puzzle, including multiple different scenarios of...
Charged lepton flavor violation arises in the Standard Model Effective Field Theory at mass dimension six. The operators that induce neutrinoless muon and tauon decays are among the best constrained and are sensitive to new-physics scales up to 10^7 GeV. An entirely different class of lepton-flavor-violating operators violates lepton flavors by two units rather than one and does not lead to...
Non-abelian symmetries are strong contenders as solutions to theย flavour puzzleย that seeks to explain the mass and mixing matrices of SM fermions. The Universal Texture Zero (UTZ) model charges all quark and lepton families as triplets under the $\Delta(27)$ symmetry group, while simultaneously exploiting the seesaw mechanism to generate light neutrino masses. Together with BSM triplet...
I will discuss effective field theory tools and model building efforts focused on describing probeable signals of charged lepton flavor violation at current and future muon-to-electron conversion experiments.
Belle II is considering upgrading SuperKEKB with a polarized electron beam. The introduction of beam polarization to the experiment would significantly expand the physics program of Belle II in the electroweak, dark , and lepton flavor universality sectors. For all of these future measurements a robust method of determining the average beam polarization is required to maximize the level of...
The Fermilab Muon g-2 experiment aims to measure the anomalous magnetic moment of the muon, a_mu, to a precision of 140 parts per billion. Continuing to improve the precision of this measurement permits a more detailed comparison between the experimental value and theoretical prediction. The value of a_mu is extracted by measuring the precession frequency of the muon, omega_a, along with a...
The Mu2e experiment at Fermilab will enable the search for the neutrinoless muon to electron conversion in the field of an Al nucleus, a charged lepton flavor violating process. If observed, there would be a clear indication of physics beyond the Standard Model. Mu2e aims to reach a single event sensitivity of $3\times10^{17}$, improving from the previous limit by 4 orders of magnitude. This...
Over the years, the Lorentz-boosted regime has become an attractive area for performing measurements and searches at the LHC. This has led to an increasing importance of boosted-jet tagging algorithms. The algorithms identifying jets originating from a massive particle decaying to b or c quark-antiquark pairs, employed in CMS Run 2 analyses, are shown in this talk. The talk summarises their...
Spin correlations in top-quark pair production have been recently used to measure Entanglement at high energy. In this context, the semileptonic channel may play an important role due to its large cross section. However, the unambiguous identification of the hadronic top decay products that correlated the most with the top quark polarization is challenging. In this talk, we introduce and use...
Top quark polarization measurements provide observables that are sensitive to new physics. The down-type fermion from the W decay is the most powerful spin analyzer from top, which is not straightforward to measure in hadronic decays. Most applications measure top quark spin via an optimal hadronic spin analyzer built from kinematics. In this talk, we discuss how to improve the optimal...
We study flavor changing neutral current decays of B and K mesons in the dark U(1)D model, with the dark photon/dark Z mass between 10 MeV and 2 GeV. Although the model provides an improved fit (compared to the standard model) to the differential decay distributions of B โ K(โ)l+lโ, with l = ฮผ, e, and Bs โ ฯฮผ+ฮผโ, the allowed parameter space is ruled out by measurements of atomic parity...
In light of the recent branching fraction measurement of $B^{+}\to K^{+}\nu\bar{\nu}$-decay and its deviation from the SM expectation, we analyze the prospect of an axion-like particle (ALP) as the cause of such a departure. We assume a long-lived ALP with a mass of the order of a pion that predominantly decays to two photons. We focus on the scenario where the ALP decay length is several...
Highly suppressed (Rare) $b$-quark processes provide an excellent probe into heavy New Physics (NP) scenarios in conjunction with stringent tests of the Standard Model (SM). Rare decays of the form $b \rightarrow s \nu \bar{\nu}$ appear in the $\Lambda_b \rightarrow \Lambda \nu \bar{\nu}$ channel, that has not yet been observed, but is a promising avenue of exploration at future $e^+e^-$...
The amplitudes of $B\rightarrow PP$ decays, where $P$ is a pion or a kaon, are related by flavour $SU(3)$ ($SU(3)_F$). This allows us to describe all observables for these decays in terms of $SU(3)_F$ reduced matrix elements parametrized by diagrams. Using these parameters, we performed a fit to the experimental data, and found a discrepancy at the level of 3.6$\sigma$. This discrepancy can be...
Evidence for an excess of b -> c tau nu decays, indicative of a violation of Lepton Flavor Universality (LFU), was first experimentally observed in a 2012 analysis at BaBar measuring the ratio quantities R(D()) = BF(B -> D() tau nu) / BF(B -> D(*) l nu) (l=mu,e). More results followed from the B factories supporting this anomaly, and were later joined by LHCb, which boasts a larger...
We present higher-order QCD corrections for the associated production of a top-antitop quark pair and a $W$ boson ($t{\bar t}W$ production). We calculate approximate NNLO (aNNLO) and approximate N$^3$LO (aN$^3$LO) cross sections, with second-order and third-order soft-gluon corrections added to the exact NLO QCD result, and we also include electroweak (EW) corrections through NLO. We compare...
Entanglement is an intrinsic property of quantum mechanics and its measurement probes the current understanding of the underlying quantum nature of elementary particles at a fundamental level. A measurement of the extent of entanglement in top quark and top antiquark events produced in proton-proton collisions at a center-of-mass energy of 13 TeV is presented. The events are selected based on...
It is standard to treat the up, down, and strange quarks as "light" (non-perturbative), while the charm, bottom, and top quarks are considered "heavy" (perturbative). However, this is a somewhat simplistic picture. As I will argue in my talk, charm exhibits hints of significant rescattering effects, which is a sign of the importance of non-perturbative QCD. To make my point, I propose a...
The measurement of the charge asymmetry in top-antiquark pairs is presented using data collected by the CMS detector with proton-proton collisions and center of mass energy of 13 TeV. The full Run 2 data is used, corresponding to an integrated luminosity of 138 $fb^{-1}$. Events with exactly one lepton (an electron or muon), at least two jets and missing transverse energy are considered. The...
It is known that kaon CP-violation could manifest itself in decays into neutral kaons. In particular, the CP asymmetry in $\tau\rightarrow \pi K_s \nu$ had been searched for. In this work we discuss how the measured time integrated CP asymmetry depends on the experimental detection efficiency as a function of the energy and the decay time of the kaon. We show that such dependencies of the...
We revisit the behavior of neutron interpolating currents under singlet chiral rotations and show that not all interpolating currents are good for calculating chirality-sensitive quantities. In particular, for the $\theta$-induced neutron EDM, we show that the $\beta=1$ and $\beta=-1$ current give physical answers that only depend on $\bar{\theta}=\theta_m+\theta_G$ after removing an overall...
We have reconsidered the possible new physics (NP) scenarios in the $\bar{B}\to D(D^*) \ell^-\bar{\nu}_{\ell}$ decays in light of the recent LHCb result on $R_{D^*}$ = $\frac{\Gamma(\bar{B}\to D^{*}\tau^-\bar{\nu}_{\tau})}{\Gamma(\bar{B}\to D^{*}\ell^-\bar{\nu}_{\ell})}$ ($l \in e, \mu$). The contribution from NP could be of minimal flavor violating (MFV) type which leads to similar effects in...
