Black holes radiate mainly on the brane

Glimpses on the Micro Black Hole Planck Phase

Mass thresholds, lifetimes, entropy and heat capacity for micro black holes close to their late Schwarzschild phase are computed using two different generalized uncertainty principles, in the framework of models with extra spatial dimensions. Emissions of both photons and gravitons (in the bulk) are taken into account. Results are discussed and compared.

Search for new physics in dijet angular distributions using proton-proton collisions at s = 13 TeV and constraints on dark matter and other models

A search is presented for physics beyond the standard model, based on measurements of dijet angular distributions in proton-proton collisions ats = 13 TeV . The data collected with the CMS detector at the LHC correspond to an integrated luminosity of 35.9fb - 1 . The observed distributions, corrected to particle level, are found to be in agreement with predictions from perturbative quantum chromodynamics that include electroweak corrections. Constraints are placed on models containing quark contact interactions, extra spatial dimensions, quantum black holes, or dark matter, using the detector-level distributions. In a benchmark model where only left-handed quarks participate, contact interactions are excluded at the 95% confidence level up to a scale of 12.8 or 17.5TeV, for destructive or constructive interference, respectively. The most stringent lower limits to date are set on the ultraviolet cutoff in the Arkani-Hamed-Dimopoulos-Dvali model of extra dimensions. In the Giudice-Rattazzi-Wells convention, the cutoff scale is excluded up to 10.1TeV. The production of quantum black holes is excluded for masses below 5.9 and 8.2TeV, depending on the model. For the first time, lower limits between 2.0 and 4.6TeVare set on the mass of a dark matter mediator for (axial-)vector mediators, for the universal quark couplingg q = 1.0 .

Tensile strength and the mining of black holes

There are a number of important thought experiments that involve raising and lowering boxes full of radiation in the vicinity of black hole horizons. This Letter looks at the limitations placed on these thought experiments by the null energy condition, which imposes a fundamental bound on the tensile-strength-to-weight ratio of the materials involved, makes it impossible to build a box near the horizon that is wider than a single wavelength of the Hawking quanta, and puts a severe constraint on the operation of "space elevators" near black holes. In particular, it is shown that proposals for mining black holes by lowering boxes near the horizon, collecting some Hawking radiation, and dragging it out to infinity cannot proceed nearly as rapidly as has previously been claimed. As a consequence of this limitation, the boxes and all the moving parts are superfluous and black holes can be destroyed equally rapidly by threading the horizon with strings.

Black hole radiance, short distances, and TeV gravity

Using a derivation of black hole radiance in terms of two-point functions one can provide a quantitative estimate of the contribution of short distances to the spectrum. Thermality is preserved for black holes with kappalp<<1. However, deviations from the Planckian spectrum can be found for mini black holes in TeV gravity scenarios, even before reaching the Planck phase.

Black hole particle emission in higher-dimensional spacetimes

In models with extra dimensions, a black hole evaporates both in the bulk and on the visible brane, where standard model fields live. The exact emissivities of each particle species are needed to determine how the black hole decay proceeds. We compute and discuss the absorption cross sections, the relative emissivities, and the total power output of all known fields in the evaporation phase. Graviton emissivity is highly enhanced as the spacetime dimensionality increases. Therefore, a black hole loses a significant fraction of its mass in the bulk. This result has important consequences for the phenomenology of black holes in models with extra dimensions and black hole detection in particle colliders.

Escape of black holes from the brane

TeV-scale gravity theories allow the possibility of producing small black holes at energies that soon will be explored at the CERN LHC or at the Auger observatory. One of the expected signatures is the detection of Hawking radiation that might eventually terminate if the black hole, once perturbed, leaves the brane. Here, we study how the "black hole plus brane" system evolves once the black hole is given an initial velocity that mimics, for instance, the recoil due to the emission of a graviton. The results of our dynamical analysis show that the brane bends around the black hole, suggesting that the black hole eventually escapes into the extra dimensions once two portions of the brane come in contact and reconnect. This gives a dynamical mechanism for the creation of baby branes.

Distinguishing between small Arkani-Hamed-Dimopoulos-Dvali and Randall-Sundrum accelerator-generated black holes

In models with extra dimensions that accommodate a TeV-scale gravity, small black holes could be produced in near future accelerator experiments. Such small black holes, whose gravitational radius is much smaller than the characteristic size of extra dimensions can be very well described by asymptotically flat solutions, thus losing the information about the global geometry of the extra manifold. One might conclude that such small black holes would be indistinguishable in different scenarios. We argue that important differences still exist, especially regarding experimental signature in colliders, which may help us distinguish between the various extra dimensional scenarios. The main differences come from the fact that most of the models with the warped extra dimension have an additional discrete Z2 symmetry that makes the brane behave as if it were an infinite tension brane.

Cosmogenic neutrinos and signals of TeV gravity in air showers and neutrino telescopes

The existence of extra dimensions allows the possibility that the fundamental scale of gravity is at the TeV. If that is the case, gravity could dominate the interactions of ultrahigh energy cosmic rays. In particular, the production of microscopic black holes by cosmogenic neutrinos has been estimated in a number of papers. We consider here gravity-mediated interactions at larger distances, where they can be calculated in the eikonal approximation. We show that for the expected flux of cosmogenic neutrinos these elastic processes give a stronger signal than black hole production in neutrino telescopes. Taking the bounds on the higher-dimensional Planck mass M(D) (D=4 + n) from current air shower experiments, for n=2(6) elastic collisions could produce up to 118 (34) events per year at IceCube. On the other hand, the absence of any signal would imply a bound of M(D) > or approximately 5 TeV.

Domination of black hole accretion in brane cosmology

We consider the evolution of primordial black holes formed during the high energy phase of the braneworld scenario. We show that the effect of accretion from the surrounding radiation bath is dominant compared to evaporation for such black holes. This feature lasts till the onset of matter (or black hole) domination of the total energy density which could occur either in the high energy phase or later. We find that the black hole evaporation times could be significantly large even for black holes with small initial mass to survive until several cosmologically interesting eras.

Black hole evaporation with separated fermions

In models with a low quantum gravity scale, fast proton decay can be avoided by localizing quarks and leptons to separated positions in an extra 1/TeV sized dimension with gauge and Higgs fields living throughout. Black holes with masses of the order of the quantum gravity scale are therefore expected to evaporate nonuniversally, preferentially radiating directly into quarks or leptons but not both. Should black holes be copiously produced at a future hadron collider, we find the ratio of final state jets to charged leptons to photons is 113:8:1, which differs from previous analyses that assumed all standard model fields live at the same point in the extra dimensional space.

Black hole as a point radiator and recoil effect on the brane world

A small black hole attached to a brane in a higher-dimensional space emitting quanta into the bulk may leave the brane as a result of a recoil. We construct a field theory model in which such a black hole is described as a massive scalar particle with internal degrees of freedom. In this model, the probability of transition between the different internal levels is identical to the probability of thermal emission calculated for the Schwarzschild black hole. The discussed recoil effect implies that the thermal emission of the black holes, which might be created by interaction of high energy particles in colliders, could be terminated and the energy nonconservation can be observed in the brane experiments.

Uniqueness and nonuniqueness of static black holes in higher dimensions

We prove a uniqueness theorem for asymptotically flat static charged dilaton black-hole solutions in higher-dimensional space-times. We also construct infinitely many nonasymptotically flat regular static black holes on the same space-time manifold with the same spherical topology. An application to the uniqueness of a class of flat p-branes is also given.

Black hole production and large extra dimensions

Black hole (BH) production at colliders is possible when the colliding energy is above the Planck scale, which can effectively be at TeV scale in models of large extra dimensions. In this work, we study the production of black holes at colliders and discuss the possible signatures. We point out the " ij-->BH+others" subprocesses, in which the BH and other standard-model particles are produced with a large transverse momentum. When the BH decays, it gives a signature that consists of particles of high multiplicity in a boosted spherical shape on one side of the event and a few numbers of high p(T) partons on the other side, which provide very useful tags for the event.

Discovering new physics in the decays of black holes

If the scale of quantum gravity is near a TeV, the CERN Large Hadron Collider (LHC) will be producing one black hole (BH) about every second, thus qualifying as a BH factory. With the Hawking temperature of a few hundred GeV, these rapidly evaporating BHs may produce new, undiscovered particles with masses approximately 100 GeV. The probability of producing a heavy particle in the decay depends on its mass only weakly, in contrast with the exponentially suppressed direct production. Furthermore, backgrounds in the BH sample can be made small. Using the Higgs boson as an example, we show that it may be found at the LHC on the first day of its operation, even with incomplete detectors.

Black hole production by cosmic rays

Ultrahigh energy cosmic rays create black holes in scenarios with extra dimensions and TeV-scale gravity. In particular, cosmic neutrinos will produce black holes deep in the atmosphere, initiating quasihorizontal showers far above the standard model rate. At the Auger Observatory, hundreds of black hole events may be observed, providing evidence for extra dimensions and the first opportunity for experimental study of microscopic black holes. If no black holes are found, the fundamental Planck scale must be above 2 TeV for any number of extra dimensions.

Black holes at the Large Hadron Collider

If the scale of quantum gravity is near TeV, the CERN Large Hadron Collider will be producing one black hole (BH) about every second. The decays of the BHs into the final states with prompt, hard photons, electrons, or muons provide a clean signature with low background. The correlation between the BH mass and its temperature, deduced from the energy spectrum of the decay products, can test Hawking's evaporation law and determine the number of large new dimensions and the scale of quantum gravity.