14,124 research outputs found
How classical are TeV-scale black holes?
We show that the Hawking temperature and the entropy of black holes are
subject to corrections from two sources: the generalized uncertainty principle
and thermal fluctuations. Both effects increase the temperature and decrease
the entropy, resulting in faster decay and ``less classical'' black holes. We
discuss the implications of these results for TeV-scale black holes that are
expected to be produced at future colliders.Comment: 10 pages, no figures, REVTeX style. Extra comments and references to
match version accepted to Classical and Quantum Gravit
Polaron Crossover in Molecular Solids
An analytical variational method is applied to the molecular Holstein
Hamiltonian in which the dispersive features of the dimension dependent phonon
spectrum are taken into account by a force constant approach. The crossover
between a large and a small size polaron is monitored, in one, two and three
dimensions and for different values of the adiabatic parameter, through the
behavior of the effective mass as a function of the electron-phonon coupling.
By increasing the strength of the inter-molecular forces the crossover becomes
smoother and occurs at higher {\it e-ph} couplings. These effects are more
evident in three dimensions. We show that our Modified Lang-Firsov method
starts to capture the occurence of a polaron self-trapping transition when the
electron energies become of order of the phonon energies. The self-trapping
event persists in the fully adiabatic regime. At the crossover we estimate
polaron effective masses of order times the bare band mass
according to dimensionality and value of the adiabatic parameter. Modified
Lang-Firsov polaron masses are substantially reduced in two and three
dimensions. There is no self-trapping in the antiadiabatic regime.Comment: To be published in J.Phys.:Condensed Matte
Diffusion of charm and beauty in the Glasma
Relativistic nuclear collisions offer a unique way to study strong
interactions at very high energy. The collision process can be described within
the gluon saturation framework as the interaction of two colored glasses, and
because of this interaction strong longitudinal gluon fields, namely the
Glasma, are produced immediately after the collision. Besides, heavy quarks are
also produced in the very early stage and because of their large mass and small
concentration, their motion does not affect the evolution of the Glasma, thus
behaving as ideal probes of the Glasma itself. We study the evolution of the
heavy quarks in the Glasma allegedly produced in high energy p-Pb collisions by
solving consistently the equations of motion of the quarks in the evolving
Glasma fields. We find that this motion can be understood in terms of diffusion
in momentum space, similarly to the random motion of a heavy probe in a hot
thermalized medium. We show how the diffusion of heavy probes affects the
nuclear modification factor of D and B mesons in p-Pb collisions.Comment: Talk given by M. R. at QCD@Work2018 held in Matera, Italy, 25-28 June
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Aging and Crossovers in Phase-Separating Fluid Mixtures
We use state-of-the-art molecular dynamics simulations to study hydrodynamic
effects on aging during kinetics of phase separation in a fluid mixture. The
domain growth law shows a crossover from a diffusive regime to a viscous
hydrodynamic regime. There is a corresponding crossover in the autocorrelation
function from a power-law behavior to an exponential decay. While the former is
consistent with theories for diffusive domain growth, the latter results as a
consequence of faster advective transport in fluids for which an analytical
justification has been provided.Comment: 6 pages, 4 figure
Remaining inconsistencies with solar neutrinos: can spin flavour precession provide a clue?
A few inconsistencies remain after it has been ascertained that LMA is the
dominant solution to the solar neutrino problem: why is the SuperKamiokande
spectrum flat and why is the Chlorine rate prediction over two standard
deviations above the data. There also remains the ananswered and important
question of whether the active neutrino flux is constant or time varying. We
propose a scenario involving spin flavour precession to sterile neutrinos with
three active flavours that predicts a flat SuperK spectrum and a Chlorine rate
prediction more consistent with data. We also argue that running the Borexino
experiment during the next few years may provide a very important clue as to
the possible variability of the solar neutrino flux.Comment: 3 pages, 2 figures, contribution to TAUP 2009 (Rome
A model for fermion masses and lepton mixing in SO(10) x A4
The discrete flavor symmetry A4 explains very well neutrino data at low
energy, but it seems difficult to extend it to grand unified models since in
general left-handed and right-handed fields belong to different A4
representations. Recently it has been proposed a model where all the fermions
equally transform under A4. We study here a concrete SO(10) realization of such
a model providing small neutrino masses through the seesaw mechanism. We fit at
tree level the charged fermion masses run up to the unification scale. Some
fermion masses properties come from the SO(10) symmetry while lepton mixing
angles are consequence of the A4 properties. Moreover, our model predicts the
absolute value of the neutrino masses, these ones are in the range .Comment: 15 pages. V2: Final version to appear in the journa
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