We study the properties of a previously found family of thick brane configurations in a pure geometric Weyl integrable 5D space time, a non-Riemannian generalization of Kaluza-Klein (KK) theory involving a geometric scalar field. Thus the 5D theory describes gravity coupled to a self-interacting scalar field which gives rise to the structure of the thick branes. Analyzing the graviton spectrum for this class of models, we find that a particularly interesting situation arises for a special case in which the 4D graviton is separated from the KK gravitons by a mass gap. The corresponding effective Schroedinger equation has a modified Poeschl-Teller potential and can be solved exactly. Apart from the massless 4D graviton, it contains one massive KK bound state, and the continuum spectrum of delocalized KK modes. We discuss the mass hierarchy problem, and explicitly compute the corrections to Newton's law in the thin brane limit.Comment: 6 pages in Revtex, no figures, journal version, significately revised and extende

A search for narrow resonances and quantum black holes is performed in inclusive and b-tagged dijet mass spectra measured with the CMS detector at the LHC. The data set corresponds to 5 fb −1 of integrated luminosity collected in pp collisions at √ s = 7 TeV. No narrow resonances or quantum black holes are observed. Modelindependent upper limits at the 95% confidence level are obtained on the product of the cross section, branching fraction into dijets, and acceptance for three scenarios: decay into quark-quark, quark-gluon, and gluon-gluon pairs. Specific lower limits are set on the mass of string resonances (4.31 TeV), excited quarks (3.32 TeV), axigluons and colorons (3.36 TeV), scalar color-octet resonances (2.07 TeV), E 6 diquarks (3.75 TeV), and on the masses of W (1.92 TeV) and Z (1.47 TeV) bosons. The limits on the minimum mass of quantum black holes range from 4 to 5.3 TeV. In addition, b-quark tagging is applied to the two leading jets and upper limits are set on the production of narrow dijet resonances in a model-independent fashion as a function of the branching fraction to b-jet pairs.

We present a scalar thick brane configuration arising in a theory of 5D gravity coupled to a self-interacting scalar field. We start from a classical solution of the field equations and study the physics of linear fluctuations around this background which obey a Schrodinger-like equation. We further focus our attention on a special case in which it is possible to solve this equation analytically for any massive mode. This fact allows us to make a closed analysis of the massive spectrum of Kaluza-Klein (KK) excitations and to compute the corrections to Newton's law in the thin brane limit. There exist two bound states: the massless 4D graviton, which is free of tachyonic instabilities, and a massive KK excitation. There is also a continuous spectrum of massive KK modes. The mass gap existing between the massless and the excited modes is completely defined by the inverse of the brane thickness. This fact eliminates the experimentally dangerous arbitrarily light KK modes. Moreover, in this picture the solution of the mass hierarchy problem is very simple.

A sample of 1.3 × 105K+ → π0e+νγ candidates with less than 1% background was collected by the NA62 experiment at the CERN SPS in 2017–2018. Branching fraction measurements are obtained at percent relative precision in three restricted kinematic regions, improving on existing results by a factor larger than two. An asymmetry, possibly related to T-violation, is investigated with no evidence observed within the achieved precision.

The NA62 experiment at CERN, designed to study the ultra-rare decay K+ → π+$$ \nu \overline{\nu} $$ ν ν ¯ , has also collected data in beam-dump mode. In this configuration, dark photons may be produced by protons dumped on an absorber and reach a decay volume beginning 80 m downstream. A search for dark photons decaying in flight to μ+μ− pairs is reported, based on a sample of 1.4 × 1017 protons on dump collected in 2021. No evidence for a dark photon signal is observed. A region of the parameter space is excluded at 90% CL, improving on previous experimental limits for dark photon masses between 215 and 550 MeV/c2.