Search For Microscopic Black Holes Research Articles

Search for sphalerons: IceCube vs. LHC

We discuss the observability of neutrino-induced sphaleron transitions in the IceCube detector, encouraged by a recent paper by Tye and Wong (TW), which argued on the basis of a Bloch wave function in the periodic sphaleron potential that such transitions should be enhanced compared to most previous calculations. We calculate the dependence on neutrino energy of the sphaleron transition rate, comparing it to that for conventional neutrino interactions, and we discuss the observability of tau and multi-muon production in sphaleron-induced transitions. We use IceCube 4-year data to constrain the sphaleron rate, finding that it is comparable to the upper limit inferred previously from a recast of an ATLAS search for microscopic black holes at the LHC with ∼ 3/fb of collisions at 13 TeV. The IceCube constraint is stronger for a sphaleron barrier height E Sph ≳ 9 TeV, and would be comparable with the prospective LHC sensitivity with 300/fb of data at 14 TeV if E Sph ∼ 11 TeV.

Search for sphalerons in proton-proton collisions

In a recent paper, Tye and Wong (TW) have argued that sphaleron-induced transitions in high-energy proton-proton collisions should be enhanced compared to previous calculations, based on a construction of a Bloch wave function in the periodic sphaleron potential and the corresponding pass band structure. Here we convolute the calculations of TW with parton distribution functions and simulations of final states to explore the signatures of sphaleron transitions at the LHC and possible future colliders. We calculate the increase of sphaleron transition rates in proton-proton collisions at centre-of-mass energies of 13/14/33/100 TeV for different sphaleron barrier heights, while recognising that the rates have large overall uncertainties. We use a simulation to show that LHC searches for microscopic black holes should have good efficiency for detecting sphaleron-induced final states, and discuss their experimental signatures and observability in Run 2 of the LHC and beyond. We recast the early ATLAS Run-2 search for microscopic black holes to constrain the rate of sphaleron transitions at 13 TeV, deriving a significant limit on the sphaleron transition rate for the nominal sphaleron barrier height of 9 TeV.

Search for microscopic black holes and string balls in final states with leptons and jets with the ATLAS detector at s $$ \sqrt{s} $$ = 8 TeV

A search for an excess of events with multiple high transverse momentum objects including charged leptons and jets is presented, using 20.3 fb^-1 of proton-proton collision data recorded by the ATLAS detector at the Large Hadron Collider in 2012 at a centre-of-mass energy of sqrt(s) = 8 TeV. No excess of events beyond Standard Model expectations is observed. Using extra-dimensional models for black hole and string ball production and decay, exclusion contours are determined as a function of the mass threshold for production and the fundamental gravity scale for two, four and six extra dimensions. For six extra dimensions, mass thresholds of 4.8-6.2 TeV are excluded at 95% confidence level, depending on the fundamental gravity scale and model assumptions. Upper limits on the fiducial cross-sections for non-Standard Model production of these final states are set.

Composite charge 8/3 resonances at the LHC

In composite Higgs models with partial compositeness, the small value of the observed Higgs mass implies the existence of light fermionic resonances, the top partners, whose quantum numbers are determined by the symmetry (and symmetry breaking) structure of the theory. Here we study light top partners with electric charge 8/3, which are predicted, for instance, in some of the most natural composite Higgs realizations. We recast data from two same sign lepton searches and from searches for microscopic blackholes into a bound on its mass, M8/3 > 940 GeV. Furthermore, we compare potential reach of these searches with a specifically designed search for three same-sign lepton, both at 8 and 14 TeV. We provide a simplified model, suitable for collider analysis.

Search for microscopic black holes in a like-sign dimuon final state using large track multiplicity with the ATLAS detector

A search is presented for microscopic black holes in a like-sign dimuon final state in proton--proton collisions at sqrt(s)= 8 TeV. The data were collected with the ATLAS detector at the Large Hadron Collider in 2012 and correspond to an integrated luminosity of 20.3 fb-1. Using a high track multiplicity requirement, 0.6 +- 0.2 background events from Standard Model processes are predicted and none observed. This result is interpreted in the context of low-scale gravity models and 95% CL lower limits on microscopic black hole masses are set for different model assumptions.

Search for microscopic black holes in pp collisions at $ \sqrt{s}=8 $ TeV

Abstract A search for microscopic black holes and string balls is presented, based on a data sample of pp collisions at $ \sqrt{s}=8 $ TeV recorded by the CMS experiment at the Large Hadron Collider and corresponding to an integrated luminosity of 12 fb−1. No excess of events with energetic multiparticle final states, typical of black hole production or of similar new physics processes, is observed. Given the agreement of the observations with the expected standard model background, which is dominated by QCD multijet production, 95% confidence level limits are set on the production of semiclassical or quantum black holes, or of string balls, corresponding to the exclusions of masses below 4.3 to 6.2 TeV, depending on model assumptions. In addition, model-independent limits are set on new physics processes resulting in energetic multiparticle final states.

Search for microscopic black holes in pp collisions at $$ \sqrt {s} = {\text{7TeV}} $$

Abstract A search for microscopic black holes in pp collisions at a center-of-mass energy of 7 TeV is presented. The data sample corresponds to an integrated luminosity of 4.7 fb−1 recorded by the CMS experiment at the LHC in 2011. Events with large total transverse energy have been analyzed for the presence of multiple energetic jets, leptons, and photons, which are typical signals of evaporating semiclassical and quantum black holes, and string balls. Agreement with the expected standard model backgrounds, which are dominated by QCD multijet production, has been observed for various combined multiplicities of jets and other reconstructed objects in the final state. Model-independent limits are set on new physics processes producing high-multiplicity, energetic final states. In addition, new model-specific indicative limits are set excluding semiclassical and quantum black holes with masses below 3.8 to 5.3 TeV and string balls with masses below 4.6 to 4.8 TeV . The analysis has a substantially increased sensitivity compared to previous searches.

Search for strong gravity signatures in same-sign dimuon final states using the ATLAS detector at the LHC

A search for microscopic black holes has been performed in a same-sign dimuon final state using 1.3 fb−1 of proton–proton collision data collected with the ATLAS detector at a centre of mass energy of 7 TeV at the CERN Large Hadron Collider. The data are found to be consistent with the expectation from the Standard Model and the results are used to derive exclusion contours in the context of a low scale gravity model.

Searching for Gravity's Hidden Strength

Gravity is by far the weakest of the four known forces. The gravitational attraction between two protons is 35 orders of magnitude weaker than their electromagnetic repulsion. The weakness of gravity may not be an intrinsic property, however, but may result from the propagation of gravity in extra spatial dimensions. In his Perspective, [Feng][1] describes the search for strong gravity and extra dimensions that is now being pursued on many fronts--from tabletop probes of Newtonian gravity to searches for microscopic black holes in kilometer-scale cosmic ray detectors. Upcoming experiments will either exclude this explanation of the weakness of gravity or find evidence for a radically new view of spacetime. [1]: http://www.sciencemag.org/cgi/content/full/302/5646/795