|
|
Reig, M., Valle, J. W. F., Vaquera-Araujo, C. A., & Wilczek, F. (2017). A model of comprehensive unification. Phys. Lett. B, 774, 667–670.
Abstract: Comprehensive – that is, gauge and family – unification using spinors has many attractive features, but it has been challenged to explain chirality. Here, by combining an orbifold construction with more traditional ideas, we address that difficulty. Our candidate model features three chiral families and leads to an acceptable result for quantitative unification of couplings. A potential target for accelerator and astronomical searches emerges.
|
|
|
|
Richard, J. M., Valcarce, A., & Vijande, J. (2017). Stable heavy pentaquarks in constituent models. Phys. Lett. B, 774, 710–714.
Abstract: It is shown that standard constituent quark models produce ((c)over-barcqqq) hidden-charm pentaquarks, where c denotes the charmed quark and q a light quark, which lie below the lowest threshold for spontaneous dissociation and thus are stable in the limit where the internal (c)over-barc annihilation is neglected. The binding is a cooperative effect of the chromoelectric and chromomagnetic components of the interaction, and it disappears in the static limit with a pure chromoelectric potential. Their wave function contains color sextet and color octet configurations for the subsystems and can hardly be reduced to a molecular state made of two interacting hadrons. These pentaquark states could be searched for in the experiments having discovered or confirmed the hidden-charm meson and baryon resonances.
|
|
|
|
LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2017). First Observation of the Rare Purely Baryonic Decay B0 -> p p-bar. Phys. Rev. Lett., 119(23), 232001–10pp.
Abstract: The first observation of the decay of a B0 meson to a purely baryonic final state, B-0 -> p$(p)over-bar-$ , is reported. The proton-proton collision data sample used was collected with the LHCb experiment at center-of-mass energies of 7 and 8 TeV and corresponds to an integrated luminosity of 3.0 fb(-1). The branching fraction is determined to be B(B-0 -> p$(p)over-bar-$) = (1.25 +/- 0.27 +/- 0.18) x 10(-8), where the first uncertainty is statistical and the second systematic. The decay mode B-0 -> p$(p)over-bar-$ is the rarest decay of the B-0 meson observed to date. The decay B-s(0 )-> p$(p)over-bar-$ is also investigated. No signal is seen and the upper limit B(B-s(0) -> p$(p)over-bar-$) < 1.5 x 10(-8) at 90% confidence level is set on the branching fraction.
|
|
|
|
LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2017). Observation of D-0 meson decays to pi(+) pi(-) mu(+) mu(-) and K+ K- mu(+) mu(-) final states. Phys. Rev. Lett., 119(18), 181805–10pp.
Abstract: The first observation of the D-0 -> pi(+) pi(-) mu(+) mu(-) and D-0 -> K+ K- mu(+) mu(-) decays is reported using a sample of proton-proton collisions collected by LHCb at a center-of-mass energy of 8 TeV, and corresponding to 2 fb(-1) of integrated luminosity. The corresponding branching fractions are measured using as normalization the decay D-0 -> K- pi(+) [mu(+) mu(-)](rho 0/omega), where the two muons are consistent with coming from the decay of a rho(0) or omega meson. The results are B(D-0 -> pi(+) pi(-) mu(+) mu(-)) = (9.64 +/- 0.48 +/- 0.51 +/- 0.97) x 10(-7) and B(D-0 -> K+ K- mu(+) mu(-)) = (1.54 +/- 0.27 +/- 0.09 +/- 0.16) x 10(-7), where the uncertainties are statistical, systematic, and due to the limited knowledge of the normalization branching fraction. The dependence of the branching fraction on the dimuon mass is also investigated.
|
|
|
|
Bernabeu, J., Botella, F. J., Mavromatos, N. E., & Nebot, M. (2017). The signal of ill-defined CPT weakening entanglement in the B-d system. Eur. Phys. J. C, 77(12), 865–10pp.
Abstract: In the presence of quantum-gravity fluctuations (space-time foam), the CPT operator may be ill-defined. Its perturbative treatment leads to a modification of the Einstein-Podolsky- Rosen correlation of the neutral meson system by adding an entanglement-weakening term of the wrong exchange symmetry, the omega-effect. In the current paper we identify how to probe the complex omega in the entangled B-d system using the flavour (f)-CP(g) eigenstate decay channels: the connection between the intensities for the two timeordered decays (f, g) and (g, f) is lost. Appropriate observables are constructed allowing independent experimental determinations of Re(omega) and Im(omega), disentangled from CPT violation in the evolution Hamiltonian Re(theta) and Im(theta). 2 sigma tensions for both Re(theta) and Im(omega) are shown to be uncorrelated.
|
|
