43 research outputs found
Properties of a family of n reggeized gluon states in multicolour QCD
A general relation between families of (n+1) gluon and n gluon eigenstates of
the BKP evolution kernels in the multicolour limit of QCD is derived. It allows
to construct an (n+1) gluon eigenstate if an n gluon eigenstate is known; this
solution is Bose symmetric and thus physical for even n. A recently found
family of odderon solutions corresponds to the particular case n=2.Comment: 11 pages, 1 figur
Small x evolution: BFKL vs Dipole Picture
The relation between the two approaches is discussed both in the linear and
nonlinear regimes. It is connected to the gauge invariance and Moebius symmetry
in LL perturbative QCD. First corrections beyond the large N approximation are
discussed for the nonlinear case.Comment: 4 pages, 1 figure; Proceedings of Diffraction 2004, 13-18 september
2004, Cala Gonone, Sardinia, Ital
Inclusive 1-jet Production Cross Section at Small x in QCD: Multiple Interactions
We study corrections due to two Pomeron exchanges to the inclusive 1-jet
production cross section in the Regge limit of perturbative QCD for a finite
number of colors. By considering deep inelastic scattering on a weakly bound
two-nucleon system, we carefully follow the logic of the AGK cutting rules and
show, for the single inclusive cross section, that, due to the reggeization of
the gluon, modifications of the AGK cutting rules appear. As our main result,
we investigate and calculate the jet production vertex in the presence of a
two-Pomeron cut correction. Compared to previous studies, we find a novel
structure of the jet vertex which has not been considered before. We discuss a
few implications of this new piece.Comment: 42 pages, 22 figures, few references and comments added, to appear on
JHE
A New Odderon Solution in Perturbative QCD
We present and discuss a new bound state solution of the three gluon system
in perturbative QCD. It carries the quantum numbers of the odderon, has
intercept at one and couples to the impact factor .Comment: 11 pages, latex, 1 figur
Deformed Spectral Representation of the BFKL Kernel and the Bootstrap for Gluon Reggeization
We investigate the space of functions in which the BFKL kernel acts. For the
amplitudes which describe the scattering of colorless projectiles it is
convenient to define, in transverse coordinates, the Moebius space in which the
solutions to the BFKL equation vanish as the coordinates of the two reggeized
gluons coincide. However, in order to fulfill the bootstrap relation for the
BFKL kernel it is necessary to modify the space of functions. We define and
investigate a new space of functions and show explicitly that the bootstrap
relation is valid for the corresponding spectral form of the kernel. We
calculate the generators of the resulting deformed representation of the
sl(2,C) algebra.Comment: 22 pages, 1 figur
Diffractive eta_c photo-and electroproduction with the perturbative QCD Odderon
Using a set of new odderon states, we calculate their contribution to the
diffractive eta_c photo- and electroproduction process. Compared to previous
simple 3-gluon exchange calculations we find an enhancement of about one order
of magnitude in the cross section. The t-dependence of the cross section
exhibits a dip structure in the small t region.Comment: 16 pages, 3 eps figure
Colored Spin Systems, BKP Evolution and finite N_c effects
Even within the framework of the leading logarithmic approximation the
eigenvalues of the BKP kernel for states of more than three reggeized gluons
are unknown in general, contrary to the planar limit case where the problem
becomes integrable. We consider a 4-gluon kernel for a finite number of colors
and define some simple toy models for the configuration space dynamics, which
are directly solvable with group theoretical methods. Then we study the
dependence of the spectrum of these models with respect to the number of colors
and make comparisons with the large limit case.Comment: 17 pages, 4 figures, references update, to appear on EPJ
Non-adiabatic quantum effects from a Standard Model time-dependent Higgs vev
We consider the time-dependence of the Higgs vacuum expectation value (vev)
given by the dynamics of the Standard Model and study the non-adiabatic
production of both bosons and fermions, which is intrinsically
non-perturbative. In the Hartree approximation, we analyse the general
expressions that describe the dissipative dynamics due to the back-reaction of
the produced particles. In particular, we solve numerically some relevant cases
for the Standard Model phenomenology in the regime of relatively small
oscillations of the Higgs vev.Comment: 35 pages, 15 figures and 2 table
Cosmological Unparticle Correlators
We introduce and study an extension of the correlator of unparticle matter
operators in a cosmological environment. Starting from FRW spaces we specialize
to a de Sitter spacetime and derive its inflationary power spectrum which we
find to be almost flat. We finally investigate some consequences of requiring
the existence of a unitary boundary conformal field theory in the framework of
the dS/CFT correspondence.Comment: 8 pages, 1 figure, to appear on Phys. Lett.
Groundwater modeling of the withdrawal sustainability of Cannara artesian aquifer (Umbria-Italy)
L\u2019acquifero di Cannara (Umbria, Italia) \ue8 noto da oltre un secolo ed \ue8 uno dei principali punti di approvvigionamento di acqua potabile nella Regione Umbria. All'inizio veniva utilizzato per scopi irrigui, poich\ue9 quest'area era prevalentemente agricola fino agli anni '60. Le acque sotterranee, sfruttate da Umbra Acque S.p.A. (Societ\ue0 che fornisce l\u2019acqua potabile), sono a 150 m al di sotto il livello del suolo e sono contenute in un acquifero poroso confinato, che in origine aveva caratteristiche artesiane. Lo sfruttamento di 200-300 l/s con nove pozzi ha causato una riduzione del livello piezometrico, mantenendo le condizioni di acquifero confinato, ad eccezione di un periodo molto breve durante il quale la falda \ue8 stata depressurizzata in seguito alla siccit\ue0 e per l'aumento dei prelievi di emergenza in sostituzione di altri rifornimenti idrici potabili (da sorgenti). La presenza occasionale di ioni ferro e ammonio conferma il confinamento delle acque sotterranee la loro facies idrochimica in un ambiente redox, mentre nelle aree vicine e negli acquiferi superficiali si registrano contaminanti antropogenici (nitrati e solventi clorurati). Per la protezione di queste acque sotterranee di interesse strategico (il pi\uf9 importante campo pozzi in Umbria), sono stati rivisti tutti i dati idrologici e idrochimici disponibili e studiata la ricarica dell'acquifero. Le aliquote di prelievi idrici sostenibili e le aree di salvaguardia delle acque sotterranee sono state identificate utilizzando un modello numerico di flusso. Sono state proposte ulteriori azioni per monitorare le acque sotterranee negli acquiferi superficiale e artesiano, insieme ad una sistemazione dei pozzi esistenti.The Cannara aquifer (Umbria, Italy) has been known for more than a century, and is one of the main drinking water supplies in the Umbria Region. In the beginning it was used for irrigation purposes, since this area was mainly agricultural up to the 1960s. The groundwater\u2014exploited by Umbra Acque S.p.A. (a Company supplying drinking water)\u2014is 150 m under ground level and is contained in a porous confined aquifer, which originally had artesian characteristics. Exploitation of 200\u2013300 l/s with nine wells caused a reduction of piezometric level, maintaining the confined aquifer conditions, except for a very short period during which the aquifer was depressurised by drought, and for increase of emergency withdrawals replacing other water supplies (from springs) for drinking purposes. The occasional presence of iron and ammonium ions confirms the confinement of the groundwater and their hydrochemical facies in a redox environment, while in nearby areas and shallow aquifers anthropogenic contaminants (nitrates and chlorinated solvents) are reported. For the protection of this aquifer of strategic interest (the most important well field in Umbria), all hydrological and hydrochemical data available have been reviewed, and the aquifer recharge studied. Sustainable rates of withdrawal, and groundwater protection areas have been identified using a numerical flow model. Further action for monitoring groundwater of both shallow and artesian aquifers, together with well-revamping, have been proposed