Size Of Large Extra Dimensions Research Articles

Constraints on large extra dimensions from MINOS and MINOS+

In a model where sterile neutrinos arise as Kaluza-Klein states in large extra dimensions, we derive limits on the size of the extra dimensions from data collected by the MINOS and MINOS+ experiments. Using Fermilab’s NuMI beam exposure of 16.36 × 1020 protons-on-target we constrain the size of large extra dimensions to be smaller than 0.17 µm at 90% C.L. in the limit of a vanishing lightest active neutrino mass. Even stronger limits are obtained for non-vanishing masses.

Latest Results from MINOS and MINOS+

The MINOS and MINOS+ experiments collected accelerator beam neutrino and antineutrino data for 11 years corresponding to peak energies of 3 GeV and 6 GeV, respectively, over a baseline of 735 km. These proceedings report on new limits and constraints set by MINOS and MINOS+ in and beyond the standard three-flavor paradigm. The atmospheric neutrino mass splitting in the three-flavor model is measured to be (2.42 ± 0.09) × 10−3 eV2 for normal mass ordering and for inverted mass ordering. Constraints are set on sterile neutrinos and antineutrinos in the four-flavor model by looking for sterile-driven νμ and disappearance and sterile-driven νe and appearance. A combination of the MINOS four-flavor νμ disappearance search and the Daya Bay and Bugey-3 four-flavor disappearance searches excludes the parameter space allowed by LSND and MiniBooNE for at 90% C.L. The size of large extra dimensions is constrained to be smaller than 0.17 μm at 90% C.L. in the limit of a vanishing lightest active neutrino mass. Finally, a search for non-standard νe and appearance in MINOS is presented.

Constraints on large extra dimensions from the MINOS experiment

We report new constraints on the size of large extra dimensions from data collected by the MINOS experiment between 2005 and 2012. Our analysis employs a model in which sterile neutrinos arise as Kaluza-Klein states in large extra dimensions and thus modify the neutrino oscillation probabilities due to mixing between active and sterile neutrino states. Using Fermilab's NuMI beam exposure of $10.56 \times 10^{20}$ protons-on-target, we combine muon neutrino charged current and neutral current data sets from the Near and Far Detectors and observe no evidence for deviations from standard three-flavor neutrino oscillations. The ratios of reconstructed energy spectra in the two detectors constrain the size of large extra dimensions to be smaller than $0.45\,\mu\text{m}$ at 90% C.L. in the limit of a vanishing lightest active neutrino mass. Stronger limits are obtained for non-vanishing masses.

PROTON DECAY, BLACK HOLES, AND LARGE EXTRA DIMENSIONS

We consider proton decay in theories that contain large extra dimensions. If virtual black hole states are allowed by the theory, as is generally the case, then proton decay can proceed via virtual black holes. The experimental limits on the proton lifetime place strong constraints on the quantum gravity scale M qg (the effective Planck mass). For most theories, this implies a lower bound of M qg >1016 GeV. The corresponding bound on the size of large extra dimensions is ℓ<106/n×10-30 cm, where n is the number of such dimensions. Regrettably, for most theories this limit rules out the possibility of observing large extra dimensions at accelerators or in millimeter scale gravity experiments. Conversely, proton decay could be dominated by virtual black holes, providing an experimental probe to study stringy quantum gravity physics.

Cosmological constraints on large extra dimensions

We calculate the production of massive Kaluza–Klein (KK) modes via nucleon–nucleon gravi-bremsstrahlung in the early universe. Overproduction of these states would result in early matter domination and, therefore, a low age for the universe so it is possible to place constraints on the number and size of large extra dimensions. The constraints are stronger than those from Sn1987a — for 2 large extra dimensions and T QCD=170 MeV, we show the fundamental scale must be larger than 1000 TeV.

Living inside the horizon of the D3-brane

We consider a brane world residing in the interior region inside the horizon of the D3-brane. The horizon size then can be interpreted as the compactification size. The macroscopically large size of extra dimensions can be derived from the underlying string theory that has only one physical scale, {\it i.e.,} the string scale. Then, the hierarchy between the string scale and the Planck scale is provided by Ramon-Ramon charge of the D3-brane. This picture also offers a new perspective on various issues associated with the brane world scenarios including the cosmological constant.

Infrared hierarchy, thermal brane inflation and superstrings as superheavy dark matter

In theories with TeV scale quantum gravity the standard model particles live on a brane propagating in large extra dimensions. Branes may be stabilized at large (sub-millimeter) distances from each other, either due to weak Van der Waals type interactions, or due to an infrared analog of Witten's inverse hierarchy scenario. In particular, this infrared stabilization may be responsible for a large size of extra dimensions. In either case, thermal effects can drive a brief period of the late inflation necessary to avoid the problems with high reheating temperature and the stable unwanted relics. The main reason is that the branes which repel each other at zero temperature can be temporarily glued together by thermal effects. It is crucial that the temperature needed to stabilize branes on top of each other can be much smaller than the potential energy of the bound-state, which drives inflation. After 10–15 e-foldings bound-states cool below the critical temperature and decay ending inflation. The parallel brane worlds get separated at this stage and superstrings (of a sub-millimeter size) get stretched between them. These strings can have the right density in order to serve as a superheavy dark matter.