arXiv subjects

R. Iengo

Publications and source records attributed to R. Iengo.

13 recordsLinked to original sources

arXiv2015

A Theory-independent Way of Unambiguous Detection of Wino-like particles at LHC

We propose to use the change of the energy lost by ionization, measured by silicon detectors, before and after the passage through a bulk of dense matter, for unambiguously detecting highly massive single-charged particles, which could be produced at LHC, in particular Winos with mass in the TeV range, whose c-tau is expected to be some cms long, although the method is also efficient for masses down to 10GeV. For convenience, a QED derivation of the modern version of the Bethe-Block formula is also provided.

hep-ph↗

arXiv2009

Sommerfeld enhancement: general results from field theory diagrams

Assuming that two incoming annihilating particles interact by a generally massive attractive vector potential,we find, by taking the non-relativistic limit of the field theory ladder diagrams, that the complete annihilation amplitude A is equal to: the convolution of a solution of the Schroedinger equation (including the vector potential) with the Fourier transform of the bare (i.e. ignoring the attraction) annihilation amplitude A0. The main novelty is that A0 is completely arbitrary. In particular for a massless vector potential we find for the l-partial-wave cross-section the Sommerfeld enhancement 2pi/(l!)^2 (alpha/ v)^{2l+1} (v relative velocity), e.g. for the P wave the enhancement 2pi(alpha/ v)^3.

hep-ph↗

arXiv2009

Sommerfeld enhancement for a Yukawa potential

We show how easy it is to get the Sommerfeld enhancement for a Yukawa potential, for definite partial waves, beyond the S wave analyzed in previous literature. In particular, we report results for the P wave (for which there is a resonant pattern and the enhancement can be of several orders of magnitude even far from the resonance) that could be relevant for the analysis of experimental cosmic rays data possibly signaling the annihilation of dark matter particles.

hep-ph↗

arXiv2006

Black hole formation from collisions of cosmic fundamental strings

We develop the general formalism for joining, splitting and interconnection of closed and open strings. As an application, we study examples of fundamental cosmic string collisions leading to gravitational collapse. We find that the interconnection of two strings of equal and opposite maximal angular momentum and arbitrarily large mass generically leads to the formation of black holes, provided their relative velocity is small enough.

hep-th↗

arXiv2002

Quantum entanglement of charges in bound states with finite-size dyons

We show that the presence of finite-size monopoles can lead to a number of interesting physical processes involving quantum entanglement of charges. Taking as a model the classical solution of the N=2 SU(2) Yang-Mills theory, we study interaction between dyons and scalar particles in the adjoint and fundamental representation. We find that there are bound states of scalars and dyons, which, remarkably, are always an entangled configuration of the form |ψ> =|dyon+> |scalar-> +/- |dyon->|scalar+>. We determine the energy levels and the wave functions and also discuss their stability.

hep-th↗

arXiv2002

Landau Levels in the noncommutative $AdS_2$

We formulate the Landau problem in the context of the noncommutative analog of a surface of constant negative curvature, that is $AdS_2$ surface, and obtain the spectrum and contrast the same with the Landau levels one finds in the case of the commutative $AdS_2$ space.

hep-th↗

arXiv1998

D3-branes dynamics and black holes

Using the D3-brane as the fundamental tool, we adress two aspects of D-branes physics. The first regards the interaction between two electromagnetic dual D-branes in 10 dimensions. In particular, we give a meaning to {\it both} even and odd spin structure contributions, the latter being non vanishing for non zero relative velocity $v$ (and encoding the Lorentz-like contribution). The second aspect regards the D-brane/black holes correspondence. We show how the 4 dimensional configuration corresponding to a {\it single} D3-brane wrapped on the orbifold T^6/Z_3 represents a regular Reissner-Nordstrom solution of d=4 N=2 supergravity

hep-th↗

arXiv1998

Black hole - D-brane correspondence: An example

We explore the connection between D-branes and black holes in one particular case: a $D3$-brane compactified to four dimensions on $T^6/Z_3$. Using the $D$-brane boundary state description we show the equivalence with a double extremal N=2 black hole solution of four dimensional supergravity.

hep-th↗

arXiv1998

Pair Production of Open Strings - Relativistic versus Dissipative Dynamics

We study the pair production of open strings in constant electric fields, using a general framework which encodes both relativistic string theory and generic linearly extended systems as well. In the relativistically invariant case we recover previous results, both for pair production and for the effective Born-Infeld action. We then derive a non-relativistic limit - where the propagation velocity along the string is much smaller than the velocity of light - obtaining quantum dissipation. We calculate the pair nucleation rate for this case, which could be relevant for applications.

hep-th↗

arXiv1995

UV asymptotically free QED as a broken YM theory in the unitary gauge

We compute the $β$-function of a YM theory, broken to $U(1)$, by evaluating the coupling constant renormalization in the broken phase. We perform the calculation in the unitary gauge where only physical particles appear and the theory looks like a version of QED containing massive charged spin 1 particles. We consider an on-shell scattering process and after verifying that the non-renormalizable divergences which appear in the Green's functions cancel in the expression of the amplitude, we show that the coupling constant renormalization is entirely due to the photon self-energy as in QED. However we get the expected asymptotic freedom and the physical charge decreases logarithmically as a function of the symmetry breaking scale.

hep-th↗

arXiv1993

Quantum mechanics and quantum Hall effect on Riemann surfaces

The quantum mechanics of a system of charged particles interacting with a magnetic field on Riemann surfaces is studied. We explicitly construct the wave functions of ground states in the case of a metric proportional to the Chern form of the $θ$-bundle, and the wave functions of the Landau levels in the case of the the Poincar{\' e} metric. The degeneracy of the the Landau levels is obtained by using the Riemann-Roch theorem. Then we construct the Laughlin wave function on Riemann surfaces and discuss the mathematical structure hidden in the Laughlin wave function. Moreover the degeneracy of the Laughlin states is also discussed.

hep-th↗

arXiv1992

The Gravitational Field of String Matter When the Dilaton is Massive

We study numerically the gravitational field of a star made of massive and neutral string states for the case in which the dilaton is massive. The solution exhibits very simple scaling properties in the dilaton mass. There is no horizon and the singularity is surrounded by a halo (the physical size of which is inversely proportional to the dilaton mass) where the scalar curvature is very large and proportional to the square of the dilaton mass.

hep-th↗

arXiv1992

The Gravitational Field of String Matter

We study the scattering of a massless and neutral test particle in the gravitational field of a body (the string star) made of a large number of scalar states of the superstring. We consider two cases, the one in which these states are neutral string excitations massive already in ten dimensions and the one in which their masses (and charges) originate in the process of compactification on tori. A perturbative calculation based on superstring amplitudes gives us the deflection angle up to the second order in Newton's constant. A comparison with field theory explicitly shows which among the various massless fields of the superstring give a contribution to the scattering process. In both cases, the deflection angle is smaller than the one computed in general relativity. The perturbative series can be resummed by finding the exact solution to the classical equations of motion of the corresponding low-energy action. The space-time metric of our two examples of string stars has no horizon.

hep-th↗