Gravitational effects in ultrahigh-energy string scattering

122

We extend previous techniques for calculations of transplanckian-energy stringstring collisions to the high-energy scattering of massless closed strings from a stack of N Dp-branes in Minkowski spacetime. We show that an effective non-trivial metric emerges from the string scattering amplitudes by comparing them against the semiclassical dynamics of high-energy strings in the extremal p-brane background. By changing the energy, impact parameter and effective open string coupling λ = gN , we are able to explore various interesting regimes and to reproduce classical expectations, including tidal-force excitations, even beyond the leading-eikonal approximation.

Section: Tidal Excitation Of the Closed String At Leading Ordermentioning

confidence: 56%

High-energy string-brane scattering: leading eikonal and beyond

D’Appollonio

Vecchia

Russo

et al. 2010

122

“…Nevertheless, we find it instructive to provide here a preliminary analysis of irregular solutions in our effective-theory framework in which only graviton intermediate states are considered. Basic string effects -like graviton reggeization and ensuing string production at λ s [1][2][3], as well as diffractive and central string emission induced by tidal forces [1][2][3]21] 15 should certainly be estimated in the near future in order to see how they affect the picture, but we feel that our effective approach may still provide suggestions and questions to be answered, and is anyway needed as a ground for the estimates just mentioned.…”

Section: Jhep10(2014)085mentioning

confidence: 99%

“…15 Tidal-force production amplitudes are determined by the second (b, r)-derivatives of phaseshifts [1][2][3]21] and are thus possibly important in the whole subcritical region λs < r, b < R where (5.4) is large, so that unitarity defect [10,14] and energy balance [22,23] could be sizeably affected.…”

Section: Jhep10(2014)085mentioning

confidence: 99%

Rescattering corrections and self-consistent metric in planckian scattering

Ciafaloni

Colferai

2014

Starting from the ACV approach to transplanckian scattering, we present a development of the reduced-action model in which the (improved) eikonal representation is able to describe particles' motion at large scattering angle and, furthermore, UV-safe (regular) rescattering solutions are found and incorporated in the metric. The resulting particles' shock-waves undergo calculable trajectory shifts and time delays during the scattering process -which turns out to be consistently described by both action and metric, up to relative order R 2 /b 2 in the gravitational radius over impact parameter expansion. Some suggestions about the role and the (re)scattering properties of irregular solutionsnot fully investigated here -are also presented.

“…First, such strong growth would eventually violate the unitarity bound once E ∼ M D , indicating that a fuller string calculation is required at higher energies, where the emission and exchange of string states is no longer negligible [101][102][103][104][105][106][107][108]. Second, it shows that it is the highest energy KK states that dominate in the cross section, and since these also have the shortest wavelength their properties (and the cross section) is largely insensitive to the details of the higher-dimensional geometry [109].…”

Section: Jhep10(2011)119mentioning

confidence: 99%

Anisotropic modulus stabilisation: strings at LHC scales with micron-sized extra dimensions

Cicoli

Burgess

Quevedo

2011

151

We construct flux-stabilised Type IIB string compactifications whose extra dimensions have very different sizes, and use these to describe several types of vacua with a TeV string scale. Because we can access regimes where two dimensions are hierarchically larger than the other four, we find examples where two dimensions are micron-sized while the other four are at the weak scale in addition to more standard examples with all six extra dimensions equally large. Besides providing ultraviolet completeness, the phenomenology of these models is richer than vanilla large-dimensional models in several generic ways: (i) they are supersymmetric, with supersymmetry broken at sub-eV scales in the bulk but only nonlinearly realised in the Standard Model sector, leading to no MSSM superpartners for ordinary particles and many more bulk missing-energy channels, as in supersymmetric large extra dimensions (SLED); (ii) small cycles in the more complicated extra-dimensional geometry allow some KK states to reside at TeV scales even if all six extra dimensions are nominally much larger; (iii) a rich spectrum of string and KK states at TeV scales; and (iv) an equally rich spectrum of very light moduli exist having unusually small (but technically natural) masses, with potentially interesting implications for cosmology and astrophysics that nonetheless evade new-force constraints. The hierarchy problem is solved in these models because the extra-dimensional volume is naturally stabilised at exponentially large values: the extra dimensions are Calabi-Yau geometries with a 4D K3 or T 4 -fibration over a Open Access doi:10.1007/JHEP10 (2011)119 JHEP10 (2011)119 2D base, with moduli stabilised within the well-established LARGE-Volume scenario. The new technical step is the use of poly-instanton corrections to the superpotential (which, unlike for simpler models, are likely to be present on K3 or T 4 -fibered Calabi-Yau compactifications) to obtain a large hierarchy between the sizes of different dimensions. For several scenarios we identify the low-energy spectrum and briefly discuss some of their astrophysical, cosmological and phenomenological implications.