相关论文: Diphotons, New Vacuum Angles, and Strong CP
We study the diphoton excess at 750 GeV reported by ATLAS and CMS, by assuming that it corresponds to a new spin-two resonant state. We model this state as a massive graviton in a two-site model. We show that the very stringent bounds from…
I propose a variant invisible axion model of spontaneous CP violation at the electroweak scale without CP domain wall and `strong CP' problems. Both large size QCD and small size non-QCD instantons break CP and Peccei-Quinn symmetries, and…
We study kinematic distributions that may help characterise the recently observed excess in diphoton events at 750 GeV at the LHC Run 2. Several scenarios are considered, including spin-0 and spin-2 750 GeV resonances that decay directly…
We discuss whether the enhancement in the diphoton final state at $M_{\gamma \gamma}$ = 750 GeV, observed recently by the ATLAS and CMS Collaborations could be a neutral pseudoscalar technipion $\tilde{\pi}^0$. We considered two distinct…
The high mass neutral quantum states envisaged by theories of physics beyond the standard model can at the hadron colliders reveal themselves through their decay into a pair of photons. Once such a peak in the diphoton invariant mass…
We investigate the potential to probe physics beyond the Standard Model with isotope shift measurements of optical atomic clock transitions. We first derive the reach for generic new physics above the GeV scale at the effective field theory…
Pion electro- and photoproduction off the nucleon close to threshold is studied in covariant baryon chiral perturbation theory at O($p^3$) in the extended-on-mass-shell scheme, with the explicit inclusion of the $\Delta(1232)$ resonance.…
We describe a natural UV complete theory with a composite little Higgs. Below a TeV we have the minimal Standard Model with a light Higgs, and an extra neutral scalar. At the TeV scale there are additional scalars, gauge bosons, and…
We consider CP-violating effects in tau->K pi pi nu_tau, assuming that a charged Higgs boson provides a new amplitude that can interfere with the usual Standard Model amplitude. We consider four CP-odd observables -- the regular rate…
Assuming a heavy electroweak singlet scalar, which couples to the Standard Model gauge bosons only through loop-induced couplings, SU(2)_L x U(1)_Y gauge invariance imposes interesting patterns on its decays into electroweak gauge bosons,…
The chiral anomaly provides a smoking-gun evidence of a new confining gauge theory. Motivated by a reported event excess in a diphoton invariant mass distribution at the LHC, we discuss a scenario that a pseudo-Nambu-Goldstone (pNG) boson…
A new partial wave analysis of pion photoproduction has been obtained in the framework of fixed-t dispersion relations valid form threshold up to 500 MeV. It is based on new Mainz data for \pi^{0} and \pi^{+} production off the proton and…
Pair production of colored particles is in general accompanied by production of QCD bound states (onia) slightly below the pair-production threshold. Bound state annihilation leads to resonant signals, which in some cases are easier to see…
Recently, the D0 collaboration reported a large CP violation in the same-sign dimuon charge asymmetry which has the $3.2 \sigma$ deviation from the value estimated in the Standard Model. In this paper, several new physics models are…
We investigate to what extent the recently measured value for a non-vanishing direct CP asymmetry in D0 -> K+ K- and D0 -> pi+ pi- decays can be accommodated in the Standard Model (SM) or extensions with a constrained flavour sector, for…
The Standard Model of particle physics has a number of asymmetries suggestive of a more fundamental theory, where the symmetries are restored. If the symmetry breaking scale is the electroweak scale, new Higgs bosons beyond that of the…
The study of the $\gamma^* N\rightarrow \Delta$ reaction presents the best quantitative method to explore the deviation of hadron shapes from spherical symmetry (nonspherical amplitudes). Significant non-spherical electric (E2) and Coulomb…
The hypothetical dark photon portal connecting the visible and dark sectors of the Universe has received considerable attention in recent years, with a focus on CP-conserving kinetic mixing between the Standard Model (SM) hypercharge gauge…
We examine the possibility that the recently discovered 125 GeV higgs like resonance actually corresponds to a dilaton: the Goldstone boson of scale invariance spontaneously broken at a scale f. Comparing to LHC data we find that a dilaton…
The dilaton emerges as a pseudo-Nambu-Goldstone boson (pNGB) associated with the spontaneous breaking of scale invariance in a nearly conformal field theory (CFT). We show the existence of a wiggly dilaton potential that contains multiple…