Bounds to the Higgs Sector Masses in Minimal Supersymmetry from LHC Data

We update our analysis of the Higgs sector masses in Minimal Supersymmetry and in the Two-Higgs Doublet Model to the final ATLAS and CMS data from the 2011-2012 LHC run.Comment: 5 pages, 5 figures, comments added, references update

The New Pentaquarks in the Diquark Model

Pentaquark baryons are a natural expectation of an extended picture of hadrons where quarks and diquarks are the fundamental units. The parity/mass pattern observed, when compared to that of exotic mesons, appears as the footprint of a compact five-quark structure. What has been learned from the X,Y,Z phenomenology informs about the newly found pentaquark structure and suggests further experimental tests and directions to be explored.Comment: 4 pages, 1 figure, to appear in PL

From Pentaquarks to Dibaryons in Lambda_b(5620) decays

Pentaquarks and dibaryons are natural possibilities if diquarks are used as the building blocks to assemble hadrons. In this short note, motivated by the very recent discovery of two pentaquark states, we highlight some possible channels to search for dibaryons in Lambda_b(5620) decays.Comment: 2 pages, references added, minor modifications, to appear in Phys. Lett.

Indications of a Four-Quark Structure for the X(3872) and X(3876) Particles from Recent Belle and BABAR Data

Recent results by BELLE and BaBar point to the existence of a second X particle decaying in D^0 D^0bar pi^0, a few MeV above the X(3872). We identify the two X states with the neutral particles predicted by the 4-quark model and show that production and decays are consistent with this assignement. We consider the yet-to-be-observed charged partners and give new hints on how to look for them.Comment: 5 pages, some revision of the text, results unchanged. To appear in Phys. Rev. Let

A Theory of X and Z Multiquark Resonances

We introduce the hypothesis that diquarks and antidiquarks in tetraquarks are separated by a potential barrier. We show that this notion can answer satisfactorily long standing questions challenging the diquark-antidiquark model of exotic resonances. The tetraquark description of X and Z resonances is shown to be compatible with present limits on the non-observation of charged partners X^+-, of the X(3872) and the absence of a hyperfine splitting between two different neutral states. In the same picture, Z_c and Z_b particles are expected to form complete isospin triplets plus singlets. It is also explained why the decay rate into final states including quarkonia are suppressed with respect to those having open charm/beauty states.Comment: 6 pages, 2 figures, some points clarified. To appear in PL

Neutron Production Rates by Inverse-Beta Decay in Fully Ionized Plasmas

Recently we showed that the nuclear transmutation rates are largely overestimated in the Widom-Larsen theory of the so called `Low Energy Nuclear Reactions'. Here we show that unbound plasma electrons are even less likely to initiate nuclear transmutations.Comment: 9 pages, 1 Figure, minor revisions and clarifications, results unchanged. To appear in EPJ

Heavier Higgs Particles: Indications from Minimal Supersymmetry

We use the most recent data on the Higgs-like resonance h observed at 125 GeV to derive information about the mass of the heavier Higgs particles predicted by Minimal Supersymmetry. We treat as independent parameters the couplings of h to top quark, beauty and massive vector bosons and, in this three dimensional space, we locate the point realizing the best fit to data and compare it to the position of the Standard Model point and to the region of coupling values accommodating heavier Higgs particles in Minimal Supersymmetry. We conclude that mass values 320< M_H< 360 GeV are compatible at 2sigma with the best fit of couplings to present data, larger values being compatible at the 1sigma level. Values of 1< tan(beta)< 6 are compatible with data.Comment: 5 pages, 5 figures. Clarifications and new references adde

The Hydrogen Bond of QCD

Using the Born-Oppenheimer approximation, we show that exotic resonances, X and Z, may emerge as QCD molecular objects made of colored two-quark lumps, states with heavy-light diquarks spatially separated from antidiquarks. With the same method we confirm that doubly heavy tetraquarks are stable against strong decays. Tetraquarks described here provide a new picture of exotic hadrons, as formed by the QCD analog of the hydrogen bond of molecular physics.Comment: 5 pages, 3 figures, comments and references added. Table 1 extende

A note on polarized light from magnetars

In a recent paper it is claimed that vacuum birefringence has been experimentally observed for the first time by measuring the degree of polarization of visible light from a magnetar candidate, a neutron star with a magnetic field presumably as large as 10^13 G. The role of such a strong magnetic field is twofold. First, the surface of the star emits, at each point, polarized light with linear polarization correlated with the orientation of the magnetic field. Depending on the relative orientation of the magnetic axis of the star with the direction to the distant observer, a certain degree of polarization should be visible. Second, the strong magnetic field in the vacuum surrounding the star could enhance the effective degree of polarization observed: vacuum birefringence. We compare experimental data and theoretical expectations concluding that the conditions to support a claim of strong evidence of vacuum birefringence effects are not met