相关论文: Flavor Changing processes in Quarkonium Decays
Heavy-flavor physics offers the opportunity to make indirect tests of physics beyond the Standard Model through precision measurements, and of quantum chromodynamics (QCD) through particle production studies. The rare decays B0s, B0 and D0…
We have measured the time-dependent decay rate for the process $B \to J/\psi K^{*0}(892)$ in a sample of about 88 million $\Upsilon(4S) \to B\bar{B}$ decays collected with the BaBar detector at the PEP-II asymmetric-energy $B$ Factory at…
The top quark sector is almost decoupled from lighter quark generations due to the fact that $V_{tb}\approx$~1. The current experimental measurements of $V_{tb}$ are compatible with the Standard Model expectations but are still dominated by…
We propose novel methods to determine the $\Upsilon(4S)\to B^+B^-$ and $\Upsilon(4S)\to B^0\bar B^0$ decay rates. The precision to which they and their ratio are known yields at present a limiting uncertainty around $2\%$ in measurements of…
We discuss the potential of $\tau$-charm and B factories for the search of new physics through the study of rare $\tau$ decays. We consider decays that involve the violation of lepton flavour conservation. Such decays bear a close…
We present a search for the rare flavor-changing neutral-current decay $B^0 \to K^{\ast 0} \tau^+ \tau^-$ with data collected by the Belle II experiment at the SuperKEKB electron-positron collider. The analysis uses a 365 fb$^{-1}$ data…
The results of a search for flavor changing neutral currents in top quark decays t to Zq in events with a topology compatible with the decay chain t t-bar to Wb + Zq to ell nu b + ell ell q are presented. The search is performed with a data…
We present a search for flavor changing neutral currents via quark-gluon couplings in a sample of single top quark final states corresponding to 2.3 fb^-1 of integrated luminosity collected with the D0 detector at the Fermilab Tevatron…
We investigate a family-nonuniversal Abelian extension of hypercharge, which significantly alters the phenomenological features of the standard model. Anomaly cancellation requires that the third quark family transforms differently from the…
Uniquely heavy with mass at the weak scale, the top quark may have large flavor changing couplings to Higgs bosons that are as yet unexplored. We show that such couplings can be directly probed at the LHC through the parton subprocess…
In the framework of the nonrelativistic quantum chromodynamics factorization formalism, we study the processes of $\psi(nS)$ and $\Upsilon(nS)$ decay into a lepton pair or a charm pair associated with two jets up to the next-to-leading…
A search for flavour-changing neutral current decays of a top quark to an up-type quark ($q=u, c$) and the Standard Model Higgs boson, where the Higgs boson decays to $b\bar{b}$, is presented. The analysis searches for top quark pair events…
In full one-loop generality and in next-to-leading order in QCD, we study rare top to Higgs boson flavour changing decay processes $t\to q h$ with $q=u,c$ quarks, in the general MSSM with R-parity conservation. Our primary goal is to search…
This is a review of the SuperB project, covering the accelerator, detector, and highlights of the broad physics programme. SuperB is a flavour factory capable of performing precision measurements and searches for rare and forbidden decays…
The BaBar experiment has recently obtained some important results in the search for new physics in leptonic and lepton flavor violating decays, exploiting the complete datasets collected at the $\Upsilon(4S)$, $\Upsilon(3S)$ and…
At the LHC, bottom baryons are being produced in unprecedented quantities, which opens up a new field for flavor physics. For example, the decay $\Lambda_b \to p \mu^- \bar{\nu}$ can be used to obtain a novel determination of the CKM matrix…
Recent experimental and theoretical progress regarding B --> K(*) l+ l- decays led to improved bounds on the Wilson coefficients C_9 and C_10 of four-fermion operators of the |Delta B|=|Delta S|=1 effective Hamiltonian. We analyze the…
I review some topics in the production and decays of heavy flavours that are relevant for collider physics. In particular, I discuss the present status and some recent progress related to masses, parton densities and fragmentation functions…
We report search results for the flavor-changing neutral current process b --> d gamma with a data sample containing 274 million B meson pairs accumulated at the Upsilon(4S) resonance with the Belle detector at KEKB. We studied the…
A search for flavor-changing neutral currents in top-quark decays t to Zq is performed in events produced from the decay chain t t-bar to Zq + Wb, where both vector bosons decay leptonically, producing a final state with three leptons…