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Register a new userOn Light Resonance Interpretations of the B Decay Anomalies
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We sketch a novel method to search for light di-leptonic resonances by exploiting precision measurements of Drell-Yan production. Motivated by the recent hints of lepton flavour universality violation in $B to K^{ast} ell^+ ell^-$, we illustrate our proposal by studying the case of spin-1 resonances that couple to muons and have masses in the range of a few GeV. We show that the existing LHC data on $pp to Z/gamma^ast to mu^+ mu^-$ put non-trivial constraints on light di-muon resonance interpretations of $B$ decay anomalies in a model-independent fashion. The impact of our proposal on the long-standing discrepancy in the anomalous magnetic moment of the muon is also briefly discussed.
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We analyze the flavor structure of composite vector bosons arising in a model of vectorlike technicolor, often called hypercolor (HC), with eight flavors that form a one-family content of HC fermions. Dynamics of the composite vector bosons, referred to as HC rho in this paper, are formulated together with HC pions by the hidden local symmetry (HLS), in a way analogous to QCD vector mesons. Then coupling properties to the standard model (SM) fermions, which respect the HLS gauge symmetry, are described in a way that couplings of the HC rhos to the left-handed SM quarks and leptons are given by a well-defined setup as taking the flavor mixing structures into account. Under the present scenario, we discuss significant bounds on the model from electroweak precision tests, flavor physics, and collider physics. We also try to address B anomalies in processes such as B -> K(*) mu+ mu- and B -> D(*) tau nu, recently reported by LHCb, Belle, (ATLAS, and CMS in part.) Then we find that the present model can account for the anomaly in B -> K(*) mu+ mu- consistently with the other constraints while it predicts no significant deviations in B -> D(*) tau nu from the SM, which can be examined in the future Belle II experiment. The former is archived with the form C9 = -C10 of the Wilson coefficients for effective operators of b -> s mu+ mu-, which has been favored by the recent experimental data. We also investigate current and future experimental limits at the Large Hadron Collider (LHC) and see that possible collider signals come from dijet and ditau, or dimuon resonant searches for the present scenario with TeV mass range. To conclude, the present b -> s mu+ mu- anomaly is likely to imply discovery of new vector bosons in the ditau or dimuon channel in the context of the HC rho model. Our model can be considered as a UV completion of conventional U(1) model.
Considering the recent experimental results on exclusive semileptonic $B$ meson decays showing sizable departure from their Standard Model prediction of lepton flavor universality and keeping ongoing and proposed non-standard Higgs searches in mind, we explore the charged current flavor observables ($mathcal{R}_{D^{(*)}}$, $mathcal{R}_{J/psi}$), among other $bto cell u$ transitions, in the presence of a relevant scalar current effective new physics operator. We use $B_c$ lifetime and predicted bounds on the branching fraction of $B_c to tau u$ decay as constraints. We show the allowed parameter space in terms of the real and imaginary parts of the corresponding Wilson coefficients for such interactions. Under the light of obtained results, we study the prospect of two benchmark models, rendering the Wilson coefficients real (Georgi-Machacek (GM)) and complex (Leptoquark (LQ)) respectively. We show that constraints from $bto cell u$ on GM parameters are consistent with other flavor constraints on the model, if we drop the Babar~results. Including those disfavors the model by more than $3sigma$. On the other hand, one benchmark LQ scenario, which gives rise to a single scalar current effective interaction, is still allowed within $68%$ confidence level, albeit with a shrunk parameter space.
Recently, the LHCb collaboration has reported the excesses in the $b to s ll$ processes. One of the promising candidates for new physics to explain the anomalies is the extended Standard Model (SM) with vector-like quarks and leptons. In that model, Yukawa couplings between the extra fermions and SM fermions are introduced, adding extra scalars. Then, the box diagrams involving the extra fields achieve the $b to s ll$ anomalies. It has been known that the excesses require the large Yukawa couplings of leptons, so that this kind of model can be tested by studying correlations with other observables. In this paper, we consider the extra scalar to be a dark matter (DM) candidate, and investigate DM physics as well as the flavor physics and the LHC physics. The DM relic density and the direct-detection cross section are also dominantly given by the Yukawa couplings, so that we find some explicit correlations between DM physics and the flavor physics. In particular, we find the predictions of the $b to s ll$ anomalies against the direct detection of DM.
We study the phenomenology of light scalars of masses $m_1$ and $m_2$ coupling to heavy flavour-violating vector bosons of mass $m_V$. For $m_{1,2}lesssim $ few GeV, this scenario triggers the rare $B$ meson decays $B_s^0to 3mu^+ 3mu^-$, $B^0to 3mu^+ 3mu^-$, $B^+to K^+ 3mu^+ 3mu^-$ and $B_s^0to K^{0*} 3mu^+ 3mu^-$; the last two being the most important ones for $m_1sim m_2$. None of these signals has been studied experimentally; therefore we propose analyses to test these channels at the LHCb. We demonstrate that the reach of this facility extends to branching ratios as small as $6.0times 10^{-9}$, $1.6times 10^{-9}$, $5.9times 10^{-9}$ and $1.8times 10^{-8}$ for the aforementioned channels, respectively. For $m_{1,2}gg mathcal{O}(1)$ GeV, we show that slightly modifi
This paper intends to collect the various evidences observed by ATLAS and CMS within searches for heavy scalars and pseudocalars. These searches in tt, hZ, tautau and 2jets+W, obtain individual excesses in five channels, each at a modest level of significance, ~3 standard deviations, but, put together, give a strong evidence for a pseudoscalar at ~400 GeV. Preliminary interpretations are given which suggest that additional observations should appear in the HL-LHC phase.
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