Radiative stability of tiny cosmological constant from the Swampland and quantized compactification

We address a quantization mechanism that can allow us to understand why the cosmological constant is not large under the quantum corrections from studying the circle compactification solution of the Standard Model coupled to Einstein gravity which is subject to the constraint of the Swampland conjectures. A novel result in the present work compared to the previous investigations in the literature is that the radius of the compactified dimension and the 4D cosmological constant $\Lambda_4$ must in fact be quantized. The quantization rule of the cosmological constant is given by $\Lambda_4\propto n^2$ with $n=1,2,3,4,\ldots$, which means that the values of $\Lambda_4$ are not arbitrary but only its specific values are allowed. In general, the quantum corrections as well as other effects would break this quantization rule. Hence, it could prevent the quantum fluctuations from generating zero-point energy contributions to the cosmological constant.Comment: 7 pages, 1 figure. Added appendices, updated references, fixed errors and typos, removed the parts after page 3 of v1 to write a separate paper, published in PR

Flipped U(1)U(1) extended Standard Model and Majorana dark matter

We propose a general flavor-independent extension of the Standard Model (SM) with the minimal particle content, based on the symmetry $SU(3)_C\times SU(2)_L\times U(1)_{Y'}\times U(1)_X\times Z_2$. In this scenario, the charge operator is identified in terms of the charges of two $U(1)$ gauge symmetries. The light neutrino masses are generated via Type-I seesaw mechanism only with two heavy right-handed neutrinos acquiring their Majorana masses through the $U(1)_{Y'}\times U(1)_X$ symmetry breaking. We study various experimental constraints on the parameters of the model and investigate the phenomenology of the right-handed neutrino dark matter (DM) candidate assigned a $Z_2$-odd parity. We find that the most important constraints are the observed DM relic abundance, the current LHC limits, and the ambiguity of the SM neutral gauge boson mass.Comment: 21 pages, 14 figures, accepted for publication in Eur. Phys. J.

Implications for the hierarchy problem, inflation and geodesic motion from fiber fabric of spacetime

The large hierarchy between the quantum gravity and electroweak scales could be resolved by proposing the large extra dimensions with the fundamental Planck scale being of the order of the TeV scale. But, there would appear a new hierarchy between the inverse size of the extra dimensions and the fundamental Planck scale. In this paper, we will represent a resolution for the hierarchy problem where the inverse size of the extra dimension and the fundamental Planck scale would all be of the order of the TeV scale by proposing a fiber fabric of spacetime. Here, the origin of the large hierarchy is essentially due to the $\cosh$ function which is physically obtained from the dynamics of the horizontal metric in the vacuum of non-zero energy. In addition, the fiber fabric of spacetime allows to resolve the problems of the chirality fermions and stabilizing potential for the size of the extra dimension in an elegant and natural way, which are usually encountered in the higher dimensional theories. Then, we explore the inflation with the modulus of the extra dimension identified as the inflaton. Finally, we study how the geodesic motion of neutral test particles gets modified from the extension of spactime.Comment: 33 pages, 4 figure

Prediction of non-SUSY AdS conjecture on the lightest neutrino mass revisited

We study the constraint of the non-SUSY AdS conjecture on the three-dimensional vacua obtained from the compactification of the Standard Model coupled to Einstein gravity on a circle where the three-dimensional components of the four-dimensional metric are general functions of both non-compact and compact coordinates. We find from studying the wavefunction profile of the three-dimensional metric in the compactified dimension that the radius of the compactified dimension must be quantized. Consequently, the three-dimensional vacua are constrained by not only the non-SUSY AdS conjecture but also the quantization rule of the circle radius, leading to both upper and lower bounds for the mass of the lightest neutrino as $\sqrt{2}\leq m_\nu/\sqrt{\Lambda_4}<\sqrt{3}$ where $\Lambda_4\simeq5.06\times10^{-84}$ GeV$^2$ is the observed cosmological constant. This means that the lightest neutrino should have a mass around $10^{-32}$ eV or it would be well-approximately massless. With this prediction, we reconstruct the light neutrino mass matrix that is fixed by the neutrino oscillation data and in terms of three new mixing angles and six new phases for both the normal ordering and inverted ordering. In the situation that the light neutrino mass matrix is Hermitian, we calculate its numerical value in the $3\sigma$ range.Comment: 16 pages, 2 figures and 2 tables. arXiv admin note: text overlap with arXiv:2207.0596

Microstates and statistical entropy of observed black holes

We propose an ideal building of microscopic configurations for observed black holes from the compactification of Einstein gravity plus a positive cosmological constant in five dimensions on a circle and then compute their statistical entropy. To compute the statistical entropy in this work is applied to general black holes independent of the symmetries of the black hole solution such as the spherical symmetry and going beyond the class of special black holes that are supersymmetric and (near-)extremal as well as have exotic charges. The statistical entropy of black holes includes the Bekenstein-Hawking area term at leading order and sub-leading exponential corrections. We find a new exponential correction which is more meaningful than that found previously in the literature.Comment: 6 page

Collider phenomenology in emergent U(1)XU(1)_X extension of the Standard Model

We explore the phenomenology for a new neutral gauge boson which is emerged from a topologically nontrivial structure of the spacetime, focusing on its couplings to the fermions of the Standard Model. We analyze the current experimental constraints on the mass and gauge coupling of the new gauge boson, using the LEP bound and 13 TeV LHC data. In addition, we consider the future discovery prospect of the new gauge boson at the LHC with the highly integrated luminosity. Furthermore, we investigate the indirect search of the new gauge boson and its discrimination from other hypothetical gauge bosons like those that are predicted in the $U(1)_{B-L}$ and $U(1)_R$ models by considering forward-backward, left-right, and left-right-forward-backward asymmetries.Comment: 23 pages, 18 figure