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ISTITUTO NAZIONALE DI FISICA
NUCLEARE
Preventivo per l'anno 2005
Codice
Esperimento
PG12
Rapp. Naz.: Sodano P.
Rappresentante nazionale:
Struttura di appartenenza:
Posizione nell'I.N.F.N.:
Gruppo
4
Sodano P.
PG
INFORMAZIONI GENERALI
Teorie conformi applicate a problemi di materia condensata
Linea di ricerca
Laboratorio ove
si raccolgono i dati
PG12
Sigla dello
esperimento
assegnata
dal laboratorio
Acceleratore usato
Fascio
(sigla e
caratteristiche)
Effetto Hall quantistico
Processo fisico
studiato
Apparato
strumentale
utilizzato
Perugia e Napoli
Sezioni partecipanti
all'esperimento
Istituzioni esterne
all'Ente partecipanti
2 anni
Durata esperimento
Mod EC. 1
(a cura del responsabile nazionale)
ISTITUTO NAZIONALE DI FISICA NUCLEARE
Preventivo per l'anno 2005
Struttura
NA
Codice
Esperimento
PG12
Resp. loc.: Giuseppe Maiella
Gruppo
4
PREVENTIVO LOCALE DI SPESA PER L'ANNO 2005
In KEuro
IMPORTI
VOCI
DI
SPESA
DESCRIZIONE DELLA SPESA
Parziali
Totale Compet.
SJ
Collaborazione con ICTP Trieste
di cui SJ
2,0
2,0
Inviti ospiti stranieri (M. Huerta, M. Bergere, V. Pasquier)
4,0
4,0
Collaborazione con Service de Physique Teorique de Saclay
5,0
5,0
Consorzio
Ore CPU
Spazio Disco
Cassette
Altro
Totale
11,0
di cui SJ
0,0
Sono previsti interventi e/o impiantistica che ricadono sotto la disciplina della legge Merloni ?
Breve descrizione dell'intervento:
Mod EC./EN. 2
(a cura del responsabile locale)
A cura della
Comm.ne
Scientifica
Nazionale
ISTITUTO NAZIONALE DI FISICA NUCLEARE
Preventivo per l'anno 2005
Struttura
PG
Codice
Esperimento
PG12
Resp. loc.: Sodano P.
Gruppo
4
PREVENTIVO LOCALE DI SPESA PER L'ANNO 2005
In KEuro
IMPORTI
VOCI
DI
SPESA
DESCRIZIONE DELLA SPESA
Parziali
Totale Compet.
SJ
Interno: collaborazioni interne afferenti IS. Partecipazione Convegni
Nazionali
7,0
Inviti: Invito per Prof G. Zemba ( University of Bariloche), per Prof. K.
Zarembo ( Uppsala, Sweden) e per Prof. G. W. Semenoff ( University of
British Columbia (Canada).
4,0
Estero: Collaborazioni con University of British Columbia (Canada), M.I.T.
(U.S.A.). Partecipazione a Conferenze Internazionali.
12,0
Consorzio
Ore CPU
Spazio Disco
Cassette
di cui SJ
7,0
4,0
12,0
Altro
Totale
23,0
di cui SJ
0,0
Sono previsti interventi e/o impiantistica che ricadono sotto la disciplina della legge Merloni ?
Breve descrizione dell'intervento:
Mod EC./EN. 2
(a cura del responsabile locale)
A cura della
Comm.ne
Scientifica
Nazionale
ISTITUTO NAZIONALE DI FISICA NUCLEARE
Preventivo per l'anno 2005
Struttura
CS
Codice
Esperimento
PG12
Resp. loc.: D. Giuliano
Gruppo
4
PREVENTIVO LOCALE DI SPESA PER L'ANNO 2005
In KEuro
IMPORTI
VOCI
DI
SPESA
DESCRIZIONE DELLA SPESA
Parziali
Totale Compet.
SJ
Partecipazione a convegni nazionali
Collaborazione con la sede di Perugia
1,5
1,5
Partecipazione a convegni internazionali
Partecipazione a "Lattice 2005"
Collaborazione con Stanford University
1,5
1,5
1,5
Consorzio
Ore CPU
Spazio Disco
Cassette
di cui SJ
3,0
4,5
Altro
Totale
7,5
di cui SJ
0,0
Sono previsti interventi e/o impiantistica che ricadono sotto la disciplina della legge Merloni ?
Breve descrizione dell'intervento:
Mod EC./EN. 2
(a cura del responsabile locale)
A cura della
Comm.ne
Scientifica
Nazionale
ISTITUTO NAZIONALE DI FISICA NUCLEARE
Preventivo per l'anno 2005
Struttura
NA
Codice
Esperimento
PG12
Resp. loc.: Giuseppe Maiella
Gruppo
4
ALLEGATO MODELLO EC2
Mod EC./EN. 2a Pagina 1
(a cura del responsabile locale)
ISTITUTO NAZIONALE DI FISICA NUCLEARE
Preventivo per l'anno 2005
Struttura
NA
Codice
Esperimento
PG12
Resp. loc.: Giuseppe Maiella
Gruppo
4
ALLEGATO MODELLO EC2
Mod EC./EN. 2a Pagina 2
(a cura del responsabile locale)
ISTITUTO NAZIONALE DI FISICA NUCLEARE
Preventivo per l'anno 2005
Struttura
PG
Codice
Esperimento
PG12
Resp. loc.: Sodano P.
Gruppo
4
ALLEGATO MODELLO EC2
Mod EC./EN. 2a Pagina 1
(a cura del responsabile locale)
ISTITUTO NAZIONALE DI FISICA NUCLEARE
Preventivo per l'anno 2005
Struttura
PG
Codice
Esperimento
PG12
Resp. loc.: Sodano P.
Gruppo
4
ALLEGATO MODELLO EC2
Mod EC./EN. 2a Pagina 2
(a cura del responsabile locale)
Codice
Esperimento
PG12
Rapp. Naz.: Sodano P.
ISTITUTO NAZIONALE DI FISICA
NUCLEARE
Preventivo per l'anno 2005
Gruppo
4
PREVENTIVO GLOBALE DI SPESA PER L'ANNO 2005
In KEuro
A CARICO DELL' I.N.F.N.
Struttura
Missioni
interne
Inviti
SJ
CS
NA
PG
TOTALI
3,0
2,0
7,0
12,0
Materiale
di
consumo
Missioni
estere
SJ
SJ
SJ
Trasporti
e
facchinaggi
SJ
Spese
di
calcolo
Affitti
e
Materiale TOTALE
manutenz. inventariabile Compet.
SJ
SJ
SJ
SJ
4,0
4,0
4,5
5,0
12,0
7,5
11,0
23,0
8,0
21,5
41,5
NB. La colonna A carico di altri enti deve essere compilata obbligatoriamente
Mod EC./EN. 4
A
carico
di altri
Enti
(a cura del responsabile nazionale)
0,0
0,0
0,0
ISTITUTO NAZIONALE DI FISICA
NUCLEARE
Preventivo per l'anno 2005
Codice
Esperimento
PG12
Rapp. Naz.: Sodano P.
Gruppo
4
A) ATTIVITA' SVOLTA FINO A GIUGNO 2004
per l'attività svolta vedi l'attività prevista.
B) ATTIVITA' PREVISTA PER L'ANNO 2005
Iniziativa Specifica PG12:
Title: “Effective Theories, Spin Models and Quantum Criticality in String and Field Theories.”
Abstract: In the next two years our collaboration plans to investigate pertinent effective and boundary theories aimed at elucidating new
critical behaviours exhibited by string field theories and topological (and conformal) field theories. We shall study the RG fixed points of
these theories corresponding to conformal backgrounds which may be interpreted as D−branes for strings or as conformal quantum
critical points in pertinent topological field theories. In some instances, we shall resort to an effective description of the relevant models in
terms of spin models such as the XXX or the XXZ chain, whose integrability by algebraic Bethe ansatz is of paramount importance for
most of our purposes.
Research Program:
Motivation:
Effective field theories are a powerful tool to describe the physical behavior of a subset of the degrees of freedom of a theory by
integrating out the effects of the others. They often provide many informations about the physical system even without the knowledge of
the microscopic form of the interaction.
One example of a wide range of applications of the effective field theory methods is the theory of critical phenomena, where one
constructs an effective field theory for the pertinent order parameter to describe the physics around the critical point. Different phases are
traditionally classified in terms of order parameters providing a global characterization of the physical state, while local fluctuations of the
order parameter field drive the phase transitions between ordered and disordered phases. This theoretical paradigm, pioneered by
Landau, has been successful in condensed matter physics as well as particle physics, where the powerful concept of spontaneous
symmetry breaking is today being successfully tested in high energy experiments.
More recently, it has been provided evidence for the existence of new phases which cannot be distinguished by means of a local order
parameter. One elegant way of characterizing these phases uses the concept of topological order: The order parameter is, now,
non−local, since it is the expectation value of operators, which are lines or loops, and the correlation functions do not depend on the
locations of the operators but only on the braiding of the loops. In addition, the typical degeneracy of a topologically ordered ground state
is determined only by the topology of the manifold, on which the theory is defined and the statistic of quasi−particle is determined by this
degeneracy. It should be stressed that, in a different context, non−local order parameters have been very familiar to gauge theorists from
the analyses of confined gauge theories: in fact, the confined phases have been described as monopole condensates while the
deconfined states have been regarded as string condensates. These phases are usually described by Wilson loops (Polyakov loops , at
finite temperature) and disorder operators.
Two dimensional theories are very pertinent tools to investigate topological order. First of all, the Hall effect as well as typical strongly
correlated systems (such as high cuprate superconductors) are two dimensional. In addition, in two dimensions, particles can have exotic
statistics interpolating between bosons and fermions. A mark of topological order is, in fact, the existence of quasi−particles with fractional
statistics related to the ground state degeneracy; in this context, systems exhibiting non−abelian statistics are particularly interesting not
only from a theoretical point of view, but also because of their relevance for providing “error−correction schemes” in the rapidly developing
field of topological quantum computation.
Striking new physics may emerge also from the study of conformal quantum critical points. At a quantum critical point, the physics is scale
invariant but needs not to be Lorentz−invariant. A remarkable property of conformal quantum critical points is that the ground state wave
functionals of the pertinent field theory are conformally invariant in space and, thus, the equal time correlators of the quantum theory
equal suitable correlation functions of observables of a two dimensional Euclidean field theory. This behaviour is interesting since the
action of a field theory at a critical point is expected to be scale invariant (and also conformally invariant) , but the ground state is not
expected to be conformally invariant.
Effective field theories have recently been constructed also to describe the physics of some string modes, e.g. the tachyon and the vector
field, starting from the non perturbative formulation of string theory known as string field theory (SFT) and by integrating out all the other
string modes. In the last seven years the knowledge of the effective action for the string modes has led to many important new
developments in string theory. It was shown in fact that D−branes can be interpreted as soliton solutions of the tachyon effective action.
The Sen’s conjectures on tachyon condensation have found by now an explicit proof by means of the construction of the tachyon effective
action. This has clarifyed the mysteries associated with the open string tachyon which can be interpreted as the instability of the D−brane
that supports the existence of open strings. Effective string field theories can also describe the physics of unstable D−branes. This
instability disappears in the tachyon vacuum in which the D−brane decays. Moreover, starting with the appropriate tachyonic field theory
of unstable space−filling branes, one can describe lower dimensional D−branes as solitonic solutions. The Born−Infeld action can also be
derived as the a string modes effective action and it captures the physics of D−branes. In particular it provides a precise expression for
the brane tension and in its low energy limit can be obtained as a dimensional reduction of ten dimensional N=1, SYM. This has provided
many new insights in string theory among which one should mention the Matrix model for M−theory. The tachion and gauge field effective
action should provide equations of motion, whose solutions are fixed points of the corresponding non−linear beta function; the study of
these fixed points might provide, then, new results on tachyon condensation and on the description of multiple brane configurations in the
string field theory framework.
Effective theories have recently become very important also in the context of the AdS/CFT correspondence where the scale dimensions
of operators in conformal field theory are given by masses of the corresponding string states. However the computation of the anomalous
dimension of such operators is usually very non trivial. Recently it has been realized that one can construct effective Hamiltonian
describing the matrix of the one−loop anomalous dimension of the composite operators of scalar fields of N=4 SYM theory. Great
improvement in this direction comes from the observation made by Minahan and Zarembo. They noticed that the matrix of the one–loop
anomalous dimensions for the composite operators of scalar fields of N = 4 SYM theory in the planar limit is in correspondence with the
Hamiltonian of an integrable SO(6) XXX spin chain. This relation with the integrable system can then be used, by means of the Bethe
ansatz, to compute the anomalous dimension of the gauge theory operators. In the context of the gauge/string duality, it would be
interesting to try to apply this relation to theories less supersymmetric than N=4 SYM. Recently it has been proposed, in a N = 2 SYM
theory, that the matrix of the anomalous dimensions of operators dual to string states in the planar limit and at one–loop becomes the
Hamiltonian of an XXZ spin chain. One of the possible approaches to the study of less supersymmetric gauge theories dual to strings
would be the use of the discrete light−cone quantization. By constructing the effective spin Hamiltonian that provides the anomalous
dimensions of the conformal operators dual to the DLCQ string one should be able to go beyond the one−loop and planar approximation
in deriving string interactions.
Spin models provide very powerful tools to analyse also quantum criticality. Lattice gauge theories evidence an intriguing relationship
between chiral symmetry breaking (and confinement) and the emergence of a Neel ordered state in a pertinent quantum antiferromagnet.
Furthermore, there are reasons to believe that frustrated magnets may exhibit topological order and fractionalised excitations. In addition,
the analysis of the XXZ chain may provide interesting clues to analyse the phases of condensed matter systems as well as in string
theory.
Project objectives:
In the next two years our collaboration plans to investigate pertinent effective and boundary theories aimed at elucidating new critical
behaviours exhibited by string field theories and topological (and conformal) field theories. We shall study the RG fixed points of these
theories corresponding to conformal backgrounds which may be interpreted as D−branes for strings or as conformal quantum critical
points in pertinent topological field theories. In some instances, we shall resort to an effective description of the relevant models in terms
of spin models such as the XXX or the XXZ chain, whose integrability by algebraic Bethe ansatz is of paramount importance for most of
our purposes. In the following we shall list, in more detail, some of the items on which our collaboration plans to get significant results:
A) Topological Order in Planar Josephson Junction networks:
Quantum or topological order has already been extensively used in the analysis of FQH systems leading to an elegant explanation of their
robust (against a weak but, otherwise, arbitrary perturbation) ground state degeneracy and evidencing the intimate connection between
the ground state degeneracy and the anomalous statistics of quasi−particles. Josephson networks seem to provide now the interesting
opportunity to study tuneable physical systems supporting a quantum ordered state. The gauge theory approach to Josephson networks,
proposed by our group in Nucl. Phys. B474 , 641, (1996), is very apt to evidence, even with very simple network’ s topologies and
geometries −interesting and unexpected analogies with quantum Hall systems.
The idea that there is a close relationship between pertinent Josephson networks and field theories exhibiting topological order is not at all
new: in fact, we showed long ago that the zero temperature phase diagram of a planar Josephson network may be determined using the
mapping onto an abelian gauge model with topological Chern−Simons terms describing the interaction between charges and vortices and,
even longer ago, it was conjectured by Foda relationship between planar Josephson networks with magnetic frustration and pertinent
conformal c=3/2 field theories. Already these results rise the hope that Josephson networks may become soon useful devices for
quantum computation: it is of the utmost relevance the fact that, in 1997, Kitaev showed that a planar quantum system with anyonic
excitations could be regarded as a quantum computer. The unitary transformations needed for the manipulation of the quantum
information may be realized moving the anyons around each other and the results of the elaboration of the quantum information may be
read using the fusion rules of the pertinent algebra associated to the anyonic excitations. The gauge field theory approach developed by
our group provides not only a reliable estimate of the interactions between topological excitations, but allows also for a simple description
of Josephson networks by means of the mixed Chern−Simons models models: the structure of the Hilbert space of these models can be
understood in purely combinatorial terms and the highly−constrained nature of this combinatorial construction – phrased in the language
of the topology of curves on pertinent surfaces− may lay the groundwork for a proper engineering of Josephson networks useful to
implement Kitaev’s scheme of anyonic quantum computation.
We plan to investigate the relevance of mixed Chern−Simons models for the description of topological order in Josephson networks
aiming also to point out its observable consequences in experimentally attainable systems. We plan also to establish in full generality the
correspondence between Josephson networks with rather arbitrary geometry and topology and pertinent gauge theories; recently, in fact,
we have also evidenced that the network topology may strongly affect the quantum coherent properties of a Josephson array leading to
unexpected interesting behaviours.
Conformal field theory approaches may also be enlightening especially in the analysis of the fully frustrated classical XY model describing
a Josephson network in a transverse magnetic field with flux threading the plaquette equal to ½ the super conducting flux quantum. We
have by now preliminary evidence that the use of standard techniques (m−reduction technique), enabling to describe the ground state
degeneracy of quantum Hall fluids (and the statistics of quasiparticles), singles out a pertinent twisted conformal (c=2) field theory
enabling to describe the richness of the phases of this frustrated network.
B) Spin models and the AdS/CFT correspondence
String theory is believed to govern the behavior of ordinary gauge field theories in the strong coupling regime. It is a long time conjecture
that gauge theories might have a dual description as some sort of string theory. A real progress that this conjecture has seen over the last
thirty years has come indirectly from the study of gravitational effects in superstring theory, the collection of ideas called AdS/CFT
correspondence. This has provided one explicit example of a duality between gauge fields and strings defined on the spacetime
AdS5XS5. This duality is realized through the holographic principle: string theory, which is a theory of quantum gravity, has a dual
description as a quantum field theory living on the boundary of the background space.
Recently, it has been noted that the non−interacting type IIB superstring theory can be solved explicitly, in the light−cone gauge, on a
maximally supersymmetric plane−wave background. The plane−wave background can be obtained as a Penrose limit of AdS5XS5 and
the analogous limit can be taken for Yang−Mills theory to find the Yang−Mills dual of string theory on the plane−wave background. Since
superstrings on the plane wave background are more tractable than on AdS5XS5, many interesting aspects of this duality can be studied
explicitly. In particular, it gives a promising approach to understanding superstring interactions. In the original formulation by Berenstein
Maldacena and Nastase (BMN), some gauge–invariant operators of the N = 4 Super Yang–Mills theory having large R–charge were
regarded as a discretised version of the physical type IIB string on the pp–wave background. The BMN operators are single trace
operators formed by a long chain of one of the elementary scalar fields of N = 4, with the insertion of some impurities which are few other
fields and their covariant derivatives, each of them corresponding to a different excitation of the string. The anomalous dimensions of
these operators should reproduce the mass of the corresponding string state. Using the AdS/CFT dictionary one can identify the
corresponding gauge theory operators. They are built as a long chain of elementary fields, but in this case with an high number of
impurities. The computation of the anomalous dimensions of such operators is in general a very non−trivial task, due to the large number
of different fields that they contain. However it is by now clear that the formalism underlying the scaling limit is described by a quantum
mechanical system. A very interesting observation in this context was made by Minahan and Zarembo, who showed that the matrix of the
one–loop anomalous dimensions for the composite operators of scalar fields of N = 4 SYM theory in the planar limit is in correspondence
with the Hamiltonian of an integrable SO(6) spin chain. The relation with the integrable systems allows one to compute the anomalous
dimensions of the gauge theory operators by using the algebraic Bethe ansatz. It is thus conceivable that similar patterns of gauge/string
duality can be unraveled also for theories where some (or all) the supersymmetries are broken and the conformal invariance is lost.
In the light−cone quantization it is often useful to compactify the null−direction. This leads to the Discrete−Light−Cone Quantization
(DLCQ) of strings where interacting strings carry quantized units of light−cone momentum with the minimal momentum being carried by a
“string bit”. When type IIB string theory is studied in DLCQ on a pp−wave background it becomes dual to a N=2 superconformal “quiver”
gauge theory. Using the Hamiltonian approach described above, we plan to compute the anomalous dimensions of the gauge theory
operators of this theory dual to string states. The calculation should be simplified, compared to other studies on DLCQ, by the fact that
one can consider states with few units of light−cone momentum, namely few string bits, and compute the interacting spectrum of these
states from the anomalous dimension of the holographic dual gauge theory operators. Recently, in a N = 2 SYM theory, it was shown that
the matrix of the anomalous dimensions of operators dual to string states reduces at one–loop and in the planar limit to the Hamiltonian of
an XXZ spin chain. An interesting feature of this system is that it displays an anisotropy parameter D. The behaviour of the spin chain
depends critically on the value of this parameter; in particular for D > 1 the spectrum has a mass gap. This is the case of the integrable
system that was found in the N = 2 case. It would be extremely interesting to study the DLCQ string in the pp−wave background through
its dual gauge theory by constructing the effective spin Hamiltonian that provides the anomalous dimensions of the conformal operators.
In the DLCQ case in fact one should be able to go beyond the one−loop and planar approximation at least for string states with few units
of light−cone momentum.
C) Boundary Field Theory for a Josephson chain with a weak link: the two boundary sine−Gordon model.
In their seminal study of the quantum phase diagram of a one dimensional array of small grains, Glazman and Larkin −Phys. Rev. Lett.
79,3736, (1997)− have predicted the existence of a new phase equivalent to a repulsive Luttinger liquid, which separates the charge
density wave state from the superconducting state. This is possible, since the effective Hamiltonian describing the array is the one of a
spin ½ XXZ− chain in an external magnetic field, where the anisotropy parameter may take positive, as well as negative, values
depending on the constructive parameters of the chain.
The new phase may be probed by measuring the Josephson current through a chain containing a weaker link (say, in the centre) and
ending with two bulk superconductors fixing the phase difference of the superconducting order parameters at the edges of the chain ; this
provides an external voltage controlling the inter−grain chemical potential. For suitable values of the constructive network parameters it is
expected an oscillatory dependence of the Josephson current on the phase, while, in another range of parameters, one should observe a
saw−tooth diagram. Similar behaviours are exhibited if one looks at the dependence of the super current on the external flux observed for
a super−conducting ring interrupted by a Josephson junction (rf−SQUID).
We believe that an approach using a pertinent conformal field theory could provide new and interesting insights on the universal character
of the predicted behaviours; after all, similar current oscillations are a rather common feature exhibited− at low temperatures− by the
persistent edge currents for paired quantum Hall states, whose low−energy excitations are pertinently described by the theory of chiral
bosons with an Hilbert space generated by a U(1) Kac−Moody algebra. For these systems, the low temperature oscillating behaviour of
the persistent edge current may be, in some cases, evaluated exactly from the knowledge of the grand canonical partition function of a
c=1, conformal field theory. We plan to investigate in detail the significance and universality of these behaviours.
A preliminary analysis shows that, using the bosonization method for the XXZ chain, one may recover the full phase diagram of the
Josepphson network and that the two boundary sine−Gordon model provides for a complete description – in the full range of the device
parameters− of the low−energy excitations also for the 1D chain ending with bulk superconductors. In particular, we expect that the two
boundary sine Gordon model provides for an exact and non−perturbative evaluation of the critical exponents for the transition from the
parameter region where an oscillatory behaviour of the super current is expected (observed) to the region where is supposed to be
absent. We observe once again that the behaviours allowed to the 1D chain are similar to those of an rf−SQUID qu−bit: the repulsive
Luttinger phase being now the quantum ordered phase where entanglement of chiral bosons is achieved.
D) Conformal critical points in boundary string field theory
String field theory (SFT) is a nonperturbative, off−shell formulation of string in which the infinite family of fields associated with string
excitations are described by a space−time field theory action. In the last seven years there has been a new understanding of
nonperturbative objects in string theory, such as D−branes. It is by now clear that these can be interpreted as soliton solutions of SFT.
String field theory can also describe the physics of unstable D−branes and this has clarified the mysteries associated with the open string
tachyon: it is the instability of the D−brane that supports the existence of open strings. This instability disappears in the tachyon vacuum in
which the D−brane decays. Moreover, starting with the appropriate tachyonic field theory of unstable space−filling branes, one can
describe lower dimensional D−branes as solitonic solutions.
Recently we have provided a new formulation of the open string field theory known as Boundary String Field Theory (BSFT) which we
have rewritten in terms of the non−linear tachyon renormalization group (RG) b−function. In this formulation one starts with a free action
describing a conformal background and perturbs it with an interaction term defined on the world−sheet boundary. The theory then needs
renormalization and one can study the relationship between the RG and string dynamics by computing the non−linear b−function for the
couplings. In fact a consistent background for string theory has to be conformally invariant and it can be identified with the fixed points of
the RG equations. We have computed the non−linear b−function in various approximation to show that its fixed points can provide both
the on−shell scattering amplitudes and finite action (soliton) solutions of the BSFT. In the latter case the backgrounds that one finds as
conformal fixed points must be D−branes. When these are also solitons of the BSFT one can even compute their mass density, namely
their tension. We have derived the non−linear tachyon b−function to all orders in the tachyon field and to the first order in a derivative
expansion. This has allowed us to study the case of a D25−brane decaying in a single lower dimensional brane. Using the BSFT we have
computed the D−brane tension which is in a very good quantitative agreement with the expected exact value.
To show that open string field theory is sufficiently general to address arbitrary questions involving different vacua, it is clearly necessary
to show that the formalism is powerful enough to describe multiple brane vacua. A problem of this type is to find a solution of the BSFT
formulated with one D25−brane that describes two D−branes. It should be just as feasible to go from a vacuum with one D−brane to a
vacuum with two D−branes as it is to go from a vacuum with one D−brane to the empty vacuum. Despite some work on this problem,
there is as yet no evidence of a solution. It is currently unclear whether the obstacles to finding these vacua are technical or conceptual. In
this framework we plan to compute higher orders in the derivative expansion of the tachyon b−function to study the existence of other
possible conformal fixed points. Fixed points could describe multiple D−branes in which the original single space−filling D−brane is
decayed. If these fixed point solutions are also (at least approximately) finite action solutions of the BSFT, then one should be able to
compute their tension and to show that the BSFT is capable of describing also changes of consistent string backgrounds in which one
goes from a single unstable D−brane to multiple D−branes.
E) Criticality in Lattice Gauge Models:
We shall also start a project aimed at the numerical investigation of non−commutative field theories on the lattice. It is well known after the
paper by Ambjorn and coll. that numerical simulations of these models are possible due to their equivalence with twisted Eguchi−Kawai
models. It is our objective for the first year of the collaboration to investigate the emergence of striped phases in non− commutative field
theory models. It is expected that striped phases may be also relevant for quantum Hall systems when they are described by a
non−commutative Chern−Simons theory which is useful for the analysis of Hall systems at non−standard (even denominator) Jain fillings.
Our project hopes to shed some light also on this issue.
We shall also carry extensive numerical simulations of planar lattice gauge theories aimed to ascertain how chiral symmetry breaking may
depend on the number of fermion flavours, as well as to investigate some aspects of confinement−deconfinement transitions in these
models.
The numerical simulations will be carried mainly on the Beowulf clusters, now operating at Perugia and Cosenza.
Short description of the Pg12 collaboration:
PG12 is collaborating with international research institutes (Los Alamos National Laboratories, DESY−Zeuthen, M.I.T., Nordita, Saclay)
and the Universities of Berlin (Humboldt), of British Columbia (Vancouver) and Stanford U.S.A.. The Italian collaboration involves
researchers from Cosenza, Naples and Perugia universities and brings together people with complementary expertises ranging from
string theory to topological, conformal and lattice field theories. Much of the research to be carried within the project will require a close
collaboration between the participating teams. The relevant results, pertinent to the proposed research, as well as the collaborative effort
of the research teams are well documented in the list of publications appended to this proposal.
C) FINANZIAMENTI GLOBALI AVUTI NEGLI ANNI PRECEDENTI
Anno
finanziario
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
TOTALE
Missioni
interne
Missioni
estere
Inviti
Materiale di Trasporti e
consumo facchinaggi
Spese di
calcolo
Affitti e
manutenz.
In kEuro
Materiale
inventariabile
TOTALE
1,0
1,0
1,0
1,0
2,0
1,0
1,0
2,5
3,0
6,5
8,5
7,2
3,6
6,1
6,1
5,1
4,6
4,6
1,5
3,0
6,5
5,0
2,5
2,0
2,0
1,5
1,5
1,5
7,2
5,0
11,5
16,0
8,2
7,1
9,1
9,1
8,6
7,1
7,1
11,2
11,0
24,5
29,5
28,5
53,3
50,7
132,5
Mod EC. 5
(a cura del rappresentante nazionale)
Codice
Esperimento
PG12
Rapp. Naz.: Sodano P.
ISTITUTO NAZIONALE DI FISICA
NUCLEARE
Preventivo per l'anno 2005
Gruppo
4
PREVISIONE DI SPESA
Piano finanziario globale di spesa
In KEuro
ANNI
FINANZIARI
2005
TOTALI
Mod EC./EN. 6
Spese
Materiale
Affitti e
Materiale
Trasporti e
Missioni
Missioni
di
di
Inviti
manutenz. inventariabile
facchinaggi
interne
estere
calcolo
consumo
12,0 8,0
21,5
12,0 8,0
21,5
0,0
0,0
0,0
0,0
0,0
TOTALE
Compet.
41,5
41,5
(a cura del responsabile nazionale)
ISTITUTO NAZIONALE DI FISICA NUCLEARE
Preventivo per l'anno 2005
Struttura
NA
Codice
Esperimento
PG12
Resp. loc.: Giuseppe Maiella
Gruppo
4
COMPOSIZIONE DEL GRUPPO DI RICERCA
N
Qualifica
Affer.
RICERCATORE Dipendenti
Incarichi
al
%
Cognome e Nome
gruppo
.
Art.
23
Ruolo
Ricerca Assoc
1 Cristofano Gerardo
2 Maiella Giuseppe
3 Marotta Vincenzo
P.A.
P.A.
DIS
4
4
4
100
100
50
N
TECNICI
Cognome e Nome
Qualifica
Incarichi
Dipendenti
Ruolo Art. 15
Annotazioni:
mesi−uomo
Osservazioni del direttore della struttura in merito alla
disponibilità di personale e attrezzature
Mod EC./EN. 7
0
0
%
Collab.
Assoc. tecnica
tecnica
3 Numero totale dei Tecnici
2.5 Tecnici Full Time Equivalent
SERVIZI TECNICI
Denominazione
Cognome e Nome
Qualifica
Incarichi %
Ass.
Ruolo Art. 23
Tecnol.
Dipendenti
Numero totale dei Tecnologi
Tecnologi Full Time Equivalent
N
Numero totale dei ricercatori
Ricercatori Full Time Equivalent
TECNOLOGI
(a cura del responsabile locale)
0
0
ISTITUTO NAZIONALE DI FISICA NUCLEARE
Preventivo per l'anno 2005
Struttura
PG
Codice
Esperimento
PG12
Resp. loc.: Sodano P.
Gruppo
4
COMPOSIZIONE DEL GRUPPO DI RICERCA
N
1
2
3
4
5
6
7
8
RICERCATORE
Cognome e Nome
Qualifica
Dipendenti
Incarichi
Affer.
al
%
gruppo
.
Art.
23
Ruolo
RicercaAssoc
Dott.
Dott.
Dott.
Bigarini Antonio
Esposito Marco
Giusiano Giovanni
Grignani Gianluca
Mancini Francesco Paolo
Marcantonini Claudio
Orselli Marta
Sodano Pasquale
P.A.
B.P.D.
Dott.
B.P.D.
P.O.
Numero totale dei ricercatori
Ricercatori Full Time Equivalent
4
4
4
4
4
4
4
4
100
100
100
100
100
100
100
100
Cognome e Nome
Qualifica
Incarichi %
Ass.
Ruolo Art. 23
Tecnol.
Dipendenti
Numero totale dei Tecnologi
Tecnologi Full Time Equivalent
N
TECNICI
Cognome e Nome
0
0
Qualifica
Incarichi
Dipendenti
Ruolo Art. 15
Collab.
tecnica
Annotazioni:
mesi−uomo
Osservazioni del direttore della struttura in merito alla
disponibilità di personale e attrezzature
Mod EC./EN. 7
%
Assoc.
tecnica
8 Numero totale dei Tecnici
8 Tecnici Full Time Equivalent
SERVIZI TECNICI
Denominazione
N
TECNOLOGI
(a cura del responsabile locale)
0
0
ISTITUTO NAZIONALE DI FISICA NUCLEARE
Preventivo per l'anno 2005
Struttura
CS
Codice
Esperimento
PG12
Resp. loc.: D. Giuliano
Gruppo
4
COMPOSIZIONE DEL GRUPPO DI RICERCA
N
RICERCATORE
Cognome e Nome
Qualifica
Dipendenti
Incarichi
Affer.
al
%
gruppo
.
Art.
23
Ruolo
Ricerca Assoc
1 Giuliano Domenico
2 Marmottini Donatella
R.U.
AsRic
4
4
100
100
N
TECNICI
Cognome e Nome
Qualifica
Incarichi
Dipendenti
Ruolo Art. 15
Annotazioni:
mesi−uomo
Osservazioni del direttore della struttura in merito alla
disponibilità di personale e attrezzature
Mod EC./EN. 7
0
0
%
Collab.
Assoc. tecnica
tecnica
2 Numero totale dei Tecnici
2 Tecnici Full Time Equivalent
SERVIZI TECNICI
Denominazione
Cognome e Nome
Qualifica
Incarichi %
Ass.
Ruolo Art. 23
Tecnol.
Dipendenti
Numero totale dei Tecnologi
Tecnologi Full Time Equivalent
N
Numero totale dei ricercatori
Ricercatori Full Time Equivalent
TECNOLOGI
(a cura del responsabile locale)
0
0
Codice
Esperimento
PG12
Rapp. Naz.: Sodano P.
ISTITUTO NAZIONALE DI FISICA
NUCLEARE
Preventivo per l'anno 2005
Gruppo
4
MILESTONES PROPOSTE PER IL 2005
Data
completamento
Mod EC./EN. 8
Descrizione
(a cura del responsabile nazionale)