Found 8 result(s)
Regular Seminar Massimo Bianchi (Roma Tor Vergata)
at: 14:00 room G O Jones 610  abstract: Ultraplanckian collisions represent a fertile arena where to test quantum theories of gravity such as string theory. Glimpses of black hole formation and evaporation can be taken. For suitably defined infraredsafe observables, we show that the `classicalization' approach to highmultiplicity processes agrees with the ACV approach based on the resummation of ladder diagrams. Since a significant fraction of energy is lost in gravitational bremsstrahlung, we rederived the zerofrequency limit (ZFL) of the GW flux using soft graviton theorems at leading order and compute the corrections at sub and subsubleading order. For massless twoparticle elastic collisions the former is shown to vanish, while the latter takes an explicit expression which is checked against a simple treelevel process.However, if the treelevel form of the soft theorems is used at subsubleading order even when the elastic amplitude needs resummation, an unphysical IR singularity occurs due to the infinite Coulomb phase. We briefly discuss a recent proposal as how to deal with these divergences and find agreement with the eikonal approach. 
Regular Seminar Massimo Bianchi (Rome (Tor Vergata))
at: 14:00 room H503  abstract: We derive the oneinstanton effective action of N=4 super YangMills theory in terms of the N=4 onshell superfields. In the Coulomb branch, instantons correct both the MHV and nexttonextMHV higher derivative terms D^4F^{2n+2} and F^{2n+4}. We confirm at the nonperturbative level the nonrenormalization theorems for MHV F^{2n+2} terms that are expected to receive perturbative corrections only at nloops. We compute also the one and twoloop corrections to the D^4F^4 term and show that its completion under SL(2,Z) duality is consistent with the oneinstanton results. 
Exceptional Seminar Massimo Bianchi (INFN)
at: 14:00 room Room 208  abstract:

Exceptional Seminar Massimo Bianchi ()
at: 16:00 room 208  abstract: QMUL Graduate Lectures 
Exceptional Seminar Massimo Bianchi ()
at: 16:00 room 208  abstract: QMUL Graduate Lectures 
Exceptional Seminar Massimo Bianchi ()
at: 16:00 room 208  abstract: QMUL Graduate Lectures 
Regular Seminar Massimo Bianchi (Roma Tor Vergata and Imperial)
at: 13:15 room S4.23  abstract:

Regular Seminar Massimo Bianchi (Rome Tor Vergata)
at: 14:00 room E303 Queens Building  abstract: After reviewing how small BPS black holes with two charges can be described in perturbative Heterotic strings, we compute the cross section for their pair production at tree level and analyze angular and energy distributions. We consider both toroidal compactifications and FHSV orbifold model, and comment on scenari with large extra dimensions. Finally we briefly discuss how to extend our results to nonBPS, nonextremal and rotating BH's. 