Related papers: Diphotons, New Vacuum Angles, and Strong CP
The tagged quasi-free $np \to np\pi^+\pi^-$ reaction has been studied experimentally with the High Acceptance Di-Electron Spectrometer (HADES) at GSI at a deuteron incident beam energy of 1.25 GeV/nucleon ($\sqrt s \sim$ 2.42 GeV/c for the…
Pion photoproduction reactions are investigated in a dynamical coupled-channel approach based on the Juelich pi-N model, which presently includes the hadronic pi-N and eta-N stable channels as well as the pi-Delta, sigma-N and rho-N…
A 750 GeV resonance has been observed at the Run 2 LHC in the diphoton channel. In this paper, we explain this resonance as a CP-even scalar, S, that triggers the spontaneous breaking of local $U(1)_B$ or $U(1)_{B+L}$ gauge symmetries. S…
We propose a simple mechanism for copiously producing heavy Higgs bosons with enhanced decay rates to two photons at the LHC, within the context of the Minimal Supersymmetric extension of the Standard Model (MSSM). In the CP-conserving…
The vacuum of quantum chromodynamics has an incredibly rich structure at the nonperturbative level, which is intimately connected with the topology of gauge fields, and put to a test by the strong CP problem. We investigate the…
We show that in a decay of the form B_d or B_s-> P_1 P_2 gamma (where P_1 and P_2 are pseudoscalar mesons), through a flavor changing dipole transition, time dependent oscillations can reveal the presence of physics beyond the Standard…
In this paper, we study the recent 750 GeV diphoton excess in the Hill Model with vector-like fermions, in which the singlet-like Higgs boson is chosen as 750 GeV resonance and is mainly produced by the gluon fusion through vector-like top…
The QCD axion addresses the strong CP problem and dark matter via the misalignment mechanism, typically requiring a decay constant $f_a\sim \mathcal{O}(10^{12}$ GeV), unless the initial misalignment angle ($\theta_i$) is fine-tuned. This…
The neutral pion photoproduction on the proton near threshold has a very small scattering cross section when compared to the charged channels, which in ChPT is explained by strong cancellations between the lowest order pieces. Therefore it…
We explore a "partial unification" model that could explain the diphoton event excess around $750 \, \rm GeV$ recently reported by the LHC experiments. A new strong gauge group is combined with the ordinary color and hypercharge gauge…
Neutral pion photoproduction on the deuteron in the inelastic channel is studied in the threshold region from 142 to 160 MeV. The calculation is based on the use of the diagrammatic approach. Contributions from the pole diagrams, one-loop…
We argue that extensions of the Standard Model (SM) with a warped extra dimension, which successfully address the hierarchy and flavor problems of elementary particle physics, can provide an elegant explanation of the 750 GeV diphoton…
Motivated by the recent excess in the diphoton invariant mass near 750 GeV, we explore a supersymmetric extension of the Standard Model that includes the minimal set of superpartners as well as additional Dirac partner chiral superfields in…
The recent observation of a hadronic resonance $d^*$ in the proton-neutron system with isospin $I = 0$ and spin-parity $J^P = 3^+$ raises the possibility of producing other novel six-quark dibaryon configurations allowed by QCD. A dramatic…
The parity-odd effect in the Standard Model weak neutral current reveals itself in the long-range parity-violating nuclear potential generated by the pion exchanges in the $\Delta I=1$ channel with the parity-odd pion-nucleon coupling…
We study the phenomenology of a light (GeV scale) sterile neutrino sector and the pseudo-Goldstone boson (not the majoron) associated with a global symmetry in this sector that is broken at a high scale. Such scenarios can be motivated from…
Resonances with strong couplings to strangeness channels are investigated in a coupled-channels framework of kaon production with pions and photons. We find evidence for an additional D13 resonance around 1900 MeV that has a significant…
For photon virtualities of $Q^2 \gsim 20 {\rm GeV}^2$, the results of the (hard Pomeron) fit in the tensor-Pomeron model in terms of the variables $Q^2$ and the virtual-photon-proton energy squared, $W^2$, provide empirical evidence for the…
A non-standard CP-odd Higgs boson could induce a slight (but observable) lepton universality breaking in Upsilon leptonic decays. Moreover, mixing between such a pseudoscalar Higgs boson and $\eta_b$ states might shift their mass levels,…
The strong CP problem can be solved if the laws of nature are invariant under a space-time parity exchanging the Standard Model with its mirror copy. We review and extend different realizations of this idea with the aim of discussing Dark…