X mexican Workshop on Particles and Fields

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X Mexican Workshop on Particles and Fields




Instituto de Ciencias Nucleares, UNAM


Circuito Exterior C. U. Apartado Postal 70-543

Mexico, D. F.



+(52)555-622-4690 Ext. 372


Dynamical Mass Generation in Quantum Electrodynamics in weak magnetic fields

We study the dynamical generation of masses for fundamental fermions in

quenched quantum electrodynamics in the presence of magnetic fields using

Schwinger-Dyson equations. We show that, contrary to the case where the magnetic

field is strong, in the weak field limit masses are generated above a critical

value of the coupling and that this value is the same as in the case with no

magnetic field. The findings of this work might be relevant for processes

involving dynamical properties of fermion during the evolution of the early

universe where weak magnetic fields could be present.



> Name: J. Lorenzo Diaz Cruz

> e-mail address: jldiaz@fcfm.buap.mx

> Institution: FCFM-BUAP

> Postal address:

> Student? If yes specify BS, MS, or PhD.

> Title: Unificacion Higgs-Gauge

> Author(s): A. Aranda, J.L. Diaz Cruz, A. Rosado

> Abstract (less than 150 words):

In this talk we present an alternative approach to the search

for unification of the fundamental interaction. We postulate that

the electroweak interactions unify with the Higgs self-interactions

at an scale lower than the usual GUT scale. Complete unification with

the strong force occurs after extra-dimensions of GUT^-1 size open up.

A specific realization of the above ideas is presented whith a gauge

symmetry of the type SU(3)xSU(3) in 6D.


Jose Luis Lucio Martinez.

D. Delepine^1, J.L. Lucio Martinez^1 and C Ramirez^2.
2) Universidad Industrial de Santander
Carrera 27 Calle 9 Ciudad Universitaria
PBX 57- 7 6344000
Bucaramanga Colombia
We consider decays B ---> SP within the factorization approximation.

For particular channels (B a0 + pi, B -> f0 + K ) we present

predictions for the two and four quark state structure of the scalars.

We parameterize the annihilation contribution and indicate processes

for which the two and four quark structure lead different predictions.





Universidad de Colima


Bernal Diaz del Castillo 340, Col. Villa San Sebastian




3123161000 ext 48006

Nonperturbative extensions of perturbative series
We review different possible techniques which can be used to improve the

convergence of certain mathematical series or even to extract the

non-perturbative behaviour of a perturbative series. The application to a few

physical examples is discussed and a comparison with well-known techniques is




"A second order formalism for the description of spin 3/2 fields"

Mauro Napsuciale, Mariana Kirchbach


- Dr. Marco A. Reyes

- Instituto de Fisica

- Univ. de Guanajuato

"Status of pentaquark candidates"

We present a review of the evidence for the existance of pentaquark states,

the old searches, and the predictions that lead to the 2003 boom of

sightings. In particular, we will talk about the status of the

\theta^+(1540), \cascade^{--}(1862), and \theta_c(3100).


Name: Ricardo Gaitan Lozano

e-mail address: rgaitan@servidor.unam.mx

Institution: Fes-Cuautitlan, UNAM.

Postal address: Fes-Cautitlan, Campo 1, Centro de Investigaciones

Teoricas, Edificio A1, Planta Baja.

Student? NO

Title: Rare top decays in extended models.

Author(s): Ricardo Gaitan, Omar Miranda y Luis Cabral

Abstract (less than 150 words):

The extensions of the Standard Model with exotic quark singlets and

doublets introduces flavor changing neutral couplings between ordinary

fermions. Top quarks decays induced by flavor-changing neutral currents

(FCNC) are very much suppressed in the Standard Model. Their detection in

colliders such as LHC, NLC, or tevatron would be a signal of new physcis.

We evaluate several FCNC in the context of alternative left-right

symmetric models with extra isosinglet heavy fermions; In this case, FCNC

occur at tree level, and they are suppressed by the mixing between

ordinary top and charm quarks, which is poorly constrained by current

experimental values.




Christoph Peter

Facultad de Ciencias, Universidad de Colima


Bernal Diaz del Castillo #340




(312) 316-1000 Ext.:48009

Nonperturbative calculation of the Casimir effect

The Casimir energy for a massive scalar field in d dimensions between parallel

plates is calculated within the framework of variational perturbation theory. We

compare the results obtained with our regularization procedure with the

literature and discuss the advantages of our method.


Name: S.R. Juárez W.

e-mail address:rebeca@esfm.ipn.mx

Institution: Escuela Superior de Física y Matemáticas del IPN

Postal address:

Departamento de Física de la ESFM,

Unidad Profesional "Adolfo López Mateos"

Edificio 9, Col. Lindavista,

CP 07738, México, D.F.



Predictions for the Higgs mass from the stability and triviality

conditions in the SM
Author(s): S.R. Juárez W., H.G. Solís-Rodríguez, P. Kielanowski

Abstract :

We solve the renormalization group equation for the Higgs quartic

coupling to one and two loops. The energy dependence of the gauge and

Yukawa couplings is considered at the same order of approximation.

From the properties of the quartic coupling, precise bounds on the

Higgs boson mass are obtained by requiring the validity of the SM in

the whole range of energies from the top quark mass to the gran

unificatios scale.




Universidad de Colima


Bernal Díaz del Castillo No. 340 Col. Villas San Sebastián




Status of Glueball Spectrum calculations from Supergravity.

We review the current status of glueball spectra obtained via the Gravity/Gauge

duality in different supergravity backgrounds. We compare the advantages and

shortcomings of the Klebanov-Strassler, Maldacena-Nuñez and Black Hole




Name: Eric Vazquez Jauregui

e-mail address: ericvj@ifisica.uaslp.mx

Institution: Instituto de Fisica, Universidad Autonoma de San Luis Potosi

Postal address: Manuel Nava #6, Zona Universitaria,

San Luis Potosi, SLP 78240

Student? If yes specify BS, MS, or PhD. PhD Student

Title: New Decay Modes of the charmed strange baryon Xi_c+

Author(s): Eric Vazquez Jauregui, Jurgen Engelfried, SELEX Collaboration

Abstract (less than 150 words):

We report on the search for new decay modes of the Xi_c+, using data

from the SELEX experiment (Fermilab E781). After studying in detail

the reconstruction of hyperons in the SELEX apparatus, we are able to

observe new decay modes of te charmed strange baryons. First results

of this search will be reported.


Name: Arturo Fernandez Tellez

e-mail address: afernand@fcfm.buap.mx

Institution:Fac. Ciencias Fisico Matematicas, BUAP

Postal address: C. U., Av. San Claudio y Rio Verde, Puebla, Pue.

Student? If yes specify BS, MS, or PhD.

Title: Progress on ACORDE-ALICE detector.

Author(s): Arturo Fernandez, for the Mexican ACORDE group.

Abstract (less than 150 words): The ACORDE-ALICE detector is on

development. In this talk we report on the progress of the ACORDE

scintillator module array and the physics topics of interes on cosmic ray

using ACORDE and other ALICE detectors.



Recent Results from H1 (HERA)

A summary on some of the recent measurements made by the H1 collaboration

in ep collisions at HERA will be given. That will include studies on

electroweak parameters, charm and beauty structure functions of the

proton, and heavy quark production. First results on charged current cross

sections with polarised lepton beam will be presented also.

Name: Ricardo Lopez-Fernandez

e-mail address: lopezr@fis.cinvestav.mx

Institution: CINVESTAV

Postal address: Av. IPN 2508 CP 07360 Mexico DF

Student? No

Title: Recent Results from H1 (HERA)

Author(s): Ricardo Lopez-Fernandez



Name:Genaro Toledo Sanchez

e-mail address:toledo@fisica.unam.mx


Postal address:Instituto de Fisica, UNAM

A.P. 20-364, Mexico 01000 D. F.


Student? No

Title:Determination of the bag parameter as a function of density in a

model for quark matter

Author(s):G. Toledo Sanchez and J. Piekarewicz
Abstract (less than 150 words):

Studies of the quark matter phase usually relies on the value of bag

constant, which can be fixed from fits to hadrons properties. Attemps to

include a density dependent bag parameter to account for the effects of

the medium are based on the expected phenomenological behavior dictated by

the strong interaction rather than by effectively including the

interaction. In this work we model the quark matter in terms of quarks and

colors degrees of freedom and the gluons are considered by optimally

pairing the quarks via a many body potential. We determine, using

variational Monte Carlo techniques, the system conditions at high

densities from where we are able to obtain a bag parameter as a function

of density by performing a comparison of the bag model and our results,

here the nature of the bag parameter has the same spirit but is

dynamically generated through the potential interaction.





Universidad de Colima


Av. Universidad # 333

Colima, Colima



52 312 316 1135

52 312 316 1135
Ideas on electroweak symmetry breaking from extra dimensions

We will present a brief summary of some recent ideas regarding EWSB in the

context of extra dimensions. In prticular we will present a specific scenario

where the Higgs boson is identified with gauge bosons in higher dimensions.



Rafael G. Campos

TITLE: The Schwinger model on an unbounded lattice

AUTHORS: Rafael G. Campos and Eduardo S. Tútuti


We put the Schwinger model on a nonperiodic lattice constructed with zeros

of the Hermite polynomials as nodes.  Such a lattice has a well--defined

fermion derivative and a finite Fourier transform with a number of

properties. By using the Hamiltonian formalism it is possible to solve the

Schwinger model on this lattice and

to obtain asymptotically the exact value of the boson mass associated to

this model when the spacing of the lattice goes to zero.



Name:Juan Jose Godina Nava

e-mail address: jj@fis.cinvestav.mx


Postal address:07370

Student? PhD.

Title: High-accuracy critical exponents for O(N) hierarchical models

Author(s): L. Li, Y. Meurice, M.B. Oktay, and J.J. Godina Nava

Abstract (less than 150 words):

We perform high-accuracy calculations of the critical exponents of

the 3D O(N) Dyson's hierarchical model for N up to 20. We calculate

the critical temnperatures for the measure . We discuss the rate at

which the degree of polynomial truncations used in the calculations

need to be increased with N. We discuss the possibility of extracting

the coefficients of the 1/N expansion from high-accuracy data.

We show that the leading and subleading exponents agree with

Polchinsky equation with 4 digit and with Litim eauqtion with 5 digits.



Name: Eleazar Cuautle Flores

e-mail address: ecuautle@nucleares.unam.mx
Institution: Instituto de Ciencias Nucleares, UNAM
Postal address: Circuito exterior S/N, C.U.,

C.P. 04510, Mexico, D.F.

Title: Identified particle ratio in pp collisions and hadronisation scenarios
Author(s): E. Cuautle and G. Paic

The hadronization of partons into mesons and baryons is a theoretically

open problem. The ratios of baryons to meson as well as of antibaryons to

baryons measured both, in heavy ion, and nucleon-nucleon collisions are

not explained with the present algorithms, although new and interesting

scenarios based on the importance of multiple parton interactions do

exist. In the present work we will concentrate on the p/pi and pbar/p

ratios in nucleon-nucleon collisions using Pythia incorporating different

hadronisation scenarios for baryons. Two energies will be considered: 200

GeV where some results exist and the planned pp energy of 14 TeV at LHC.



Name: Andres Sandoval Espinosa

e-mail address: asandoval@fisica.unam.mx

Institution: Instituto de Fisica, UNAM

Postal address: Instituto de Fisica

Universidad Nacional Autonoma de Mexico

Apartado Postal 20-364

Ciudad Universitaria

01000 Mexico, D.F.

Student? No

Title: Construction of the ALICE V0A Trigger Detector


R. Alfaro (a), E. Belmont (a), E. Camacho (b), G. Contreras (b),

E. Cuautle (c), V. Grabski (a), G. Herrera (b), M. Linarez (a),

A. Martinez (a), M.I. Martinez (c), A. Menchaca (a), L.M. Montano (c),

G. Paic (c), A. Sandoval (a), S. Vergara (c)

(a) I. Fisica UNAM, (b) Cinvestav, (c) I. Ciencias Nucleares UNAM


The ALICE experiment at the CERN LHC collider requires fast detectors that

can provide an interaction trigger for proton-proton and Lead-Lead

collisions. They should also be able to discriminate between bean-beam and

beam-gas interactions.

We have designed a scintillator hodoscope with a wavelength shifting

fiber readout, that coupled to fine mesh anode photomultipliers can

satisfy the ALICE requirements.
Test results with various prototypes and the construction of the final

detector will be presented.



Effect of hard processes on momentum

correlations in pp and p¯p collisions

Guy Paic

Instituto de Ciencias Nucleares, UNAM, Mexico City, Mexico

Piotr Krzysztof Skowro´nski

CERN, CH-1211 Geneva 23, Switzerland and

Warsaw University of Technology, Faculty of Physics,

ul. Koszykowa 75, 00-662 Warsaw, Poland


The HBT radii extracted in p¯p and pp collisions at SPS and Tevatron

show a clear correlation with the charged particle rapidity density. We

propose to explain the correlation using a simple model where the distance

from the initial hard parton-parton scattering to the hadronization point

depends on the energy of the partons emitted. Since the particle multi-

plicity is correlated with the mean energy of the partons produced we can

explain the experimental observations without invoking scenarios that as-

sume a thermal fireball. The model has been applied with success to the

existing experimental data both in the magnitude and the intensity of the

correlation. As well, the model has been extended to pp collisions at the

LHC energy of 14 TeV. The possibilities of a better insight into the string

spatial development using 3D HBT analysis is discussed.



Name: Mario Ivan Martinez Hernandez

e-mail address: mim@nucleares.unam.mx
Institution: Instituto de Ciencias Nucleares - UNAM
Postal address: Circuito Exterior C. U., A. Postal 70-543, 04510 Mexico, D. F.
Student? No
Title: Radiation Tolerance Tests of a Scintillation Detector Readout by

Wavelength Shifting Fibers

Author(s): R. Alfaro, M. I. Martinez, L. M. Montaño, G. Paic and A. Sandoval
Abstract (less than 150 words):

We have performed radiation tolerance tests on the BCF-99-29MC wavelength

shifting fibers and the BC404 plastic scintillator from Bicron as well as on

optical couplers from Silicon Rubber. We used the 60Co gamma source at the

Instituto de Ciencias Nucleares facility to irradiate 30-cm fiber samples with

doses from 50 Krad to 1 Mrad. We also irradiated a 10x10 cm2 scintillator

detector with the WLS fibers embedded on it with a 200 krad dose and the

optical conectors between the scintillator and the PMT with doses from 100 to

300 krad. We measured the radiation damage on the materials by comparing the

pre- and post-irradiation optical transparency as a function of time.







IFM, Edificio C-3, Ciudad Universitaria




(443)3223500 ext. 4131

(443)3223500 ext. 4144
Towards the establishment of nonlinear hidden symmetries of the Skyrme model
The Skyrme model represents a SU(N) Lagrangian that includes nonlinear

interaction (higher order derivative) terms. Because of this peculiarity, the

field equations constitute nonlinear differential equations that are, in

general, hard to solve (only a few set of exact solutions is known). However,

this model has a remarkable property: it possesses regular, stable field

configurations that attain an energy minimum, the so-called solitons. The aim of

the present talk is to formulate an

approach that could lead to the establishment of nonlinear symmetries of the

Skyrme\'s field equations which, in turn, will lead to their integration. An

explicit SU(2) example is illustrated.



Abstract title: Search for gamma-ray bursts at 4550 m.a.s.l.

Presenter Oscar Martinez FCFM-BUAP

Authors: C. Alvarez, O. Martínez, R. Conde, T. Murrieta, O.

Saavedra, H.

Salazar, L. Villaseñor


Address: Facultad de Fisico-Matematicas, Benemerita

Universidad Autonoma

de Puebla

Apartado Postal 1364

City: Puebla

State: Puebla

Zip Code: 72000

Country: MEXICO

contact:Oscar Martinez omartin@fcfm.buap.mx

Text of the Abstract:

We present results from a search for GRBs in the energy

range from tens of GeVs

to one TeV with an array of 6 water Cherenkov detectors

located at 4500 m

a.s.l. as part of the high mountain observatory of Sierra

Negra (N18o59.1, W97

o 18.76) near Puebla city in Mexico. The detectors consist

of light-tight

cylindrical containers of 1 m 2 cross section filled with

750 l of purified

water; they are spaced 25 m and have a 5^Ô photomultiplier

(EMI model 9030A)

facing down along the cylindrical axis. We describe the

expected rate (charged

particles and muon components) and compare it with

preliminary experimental

results obtained by using a single-particle counting

technique for a data

taking period of several months, and their dependence with

atmospheric pressure

and other weather parameters.



Hamiltonian Noether theorem for gauge systems

V M Villanueva
Instituto de Fisica y Matematicas, Universidad Michoacana de

San Nicolas de Hidalgo,

PO Box 2-82, Morelia, Michoacan, Mexico

The Noether theorem for Hamiltonian constrained systems is re

visited. In

particular, our review presents a novel method to show that t

he gauge

transformations are generated by the conserved quantities ass

ociated with the

first class constraints. We apply these results to the non Ab

elian Yang-Mills and the bosonic string theories.


Name: Christian Schubert

e-mail address: schubert@ifm.umich.mx

Institution: IfM, UMSNH

Postal Address:

Dr. Christian Schubert


Ciudad Universitaria

Edificio C-3, Apdo. Postal 2-82

C.P. 58040, Morelia, Michoacan, Mexico

Student? No

Title: Pair creation in inhomogeneous fields from worldline


Author(s): Gerald V. Dunne and Christian Schubert


We show how to do semiclassical nonperturbative computations

within the

worldline approach to quantum field theory using ``worldline


These worldline instantons are classical solutions to the


worldline loop equations of motion, and are closed spacetime


parametrized by the proper-time. Specifically, we compute

the imaginary

part of the one loop effective action in scalar and spinor

QED using

``worldline instantons'', for a wide class of inhomogeneous

electric field backgrounds. The connection with the more usual WKB approach

is shortly discussed.




Miguel N.

CINVESTAV-Merida. Dep. de Fisica Aplicada


A. Postal 73 (Cordemex)




(999) 981 2960 ext. 250

(999) 981 2917


Extension of Geometric Scaling for the $\\gamma^*p$ Cross-section to Large $x$

Geometric scaling for the $\\gamma^*p(x,Q^2)$ cross-section has been

extensively studied in the past years. Geometric scaling means that

experimental data in the region of small Bjorken variable $x$ lie on a universal

curve, as a function of a single variable $\\tau$. In this work a detailed

analysis on the validity of geometric scaling is presented. It is shown that the

cross-section behaviour can be described as the product of two functions, a

function S describing the region of large $x$, and a function W describing the

region of low $x$. This leads to a new understanding of the success of the low

$x$ geometric scaling. Furthermore, an extension to large $x$ is achieved by

defining a reduced cross-section $\\sigma_ {\\gamma^*p}= \\gamma^*p/S$. In this

way, geometric scaling up to the highest measured values of $x$ and $Q^2$ is



Abstract title: Hybrid Extensive Air Shower Detector Array at the

University of Puebla to Study Cosmic Rays

Presenter Gonzalo Perez

FCFM-BUAP, Estudiante de Doctorado

Authors: Martinez, Oscar; Perez, Gonzalo; Salazar, Humberto and

Villaseñor Luis.


Address: Facultad de Fisico-Matematicas, Benemerita Universidad Autonoma

de Puebla

Apartado Postal 1364

City: Puebla

State: Puebla

Zip Code: 72000

Country: MEXICO

contact: Gonzalo Perez

Text of the Abstract:
We describe the performance of a hybrid extensive air shower (EAS)

detector array built on the Campus of the University of Puebla (19oN,

90oW, 800 g/cm2) to measure the energy, arrival direction and composition

of primary cosmic rays with energies around the knee of the cosmic-ray

energy spectrum. The array consists of 6 water Cherenkov detectors of

1.86m2 cross section and 12 liquid scintillator detectors of 1 m2

distributed in a square grid with a detector spacing of 20 m over an area

of 4000 m2. We discuss and report on measurements and reconstruction of

the LDF for the electromagnetic and muonic components of extensive air

showers. We also discuss the ways in which the hybrid character of the

array can be used to study inclined EASs, i.e., zenithal angle > 60

degree; and also to measure mass composition of the primary cosmic rays,

i.e., by estimating the relative contents of muons with respect to the EM



González Canales

Félix Franciscco

Instituto de Física UNAM


Apdo. Postal 20-364

México D.F.



(+52) 55 56 22 50 14

(+52) 55 56 22 50 15


Complementarity of quark and lepton mixing matrices

Recent measurements of the neutrino solar mixing angle and the Cabbibo angle

satisfy the empirical relation $\\theta_{sol} + \\theta_{C} \\simeq

\\frac{\\pi}{4}$. This empirical datum suggests the existence of a correlation

between the mixing matrices of neutrinos and quarks, the so called

complementarity of quarks and leptons. Here, we examine the possibility that

this correlation between the mixing angles of quarks and leptons originates in

the similar hierarchy of quark and charged lepton masses and the seesaw

mechanism that gives mass to the

Majorana neutrinos. We assume that the similar mass hierarchies of charged

lepton masses and quark masses allows one to represent all the mass matrices of

the Dirac fermions in terms of a Fritzsch texture.



Analysis of the Endpoint of the Tritium Beta Decay in a

Left-Right Symmetric Model

A. Guti¶errez-Rodr¶³guez 1;a, M. A. Hern¶andez-Ru¶³z 2;b and F. Ram¶³rez-S¶anchez 1

(1) Facultad de F¶³sica, Universidad Aut¶onoma de Zacatecas

Apartado Postal C-580, 98060 Zacatecas, Zacatecas M¶exico.

(a) Cuerpo Acad¶emico de Part¶³culas, Campos y Astrof¶³sica.

(2) Facultad de Ciencias Qu¶³micas, Universidad Aut¶onoma de Zacatecas

C¶odigo Postal 98068, Zacatecas, Zacatecas M¶exico.

(b) Cuerpo Acad¶emico de Ciencias B¶asicas de Q.F.B..


We start with a Left-Right Symmetric Model and we analyze the endpoint

of the beta decay of the tritium 3H ! 3He + e¡ + ¹ºe. We applied this

model to incorporate the right currents, whereby we propose an amplitude

whose leptonic part contains the parameter ¸ de¯ned as a left-right asymmetry

parameter which measures the parity violation. We realized the numerical

computation to the sensibility of the experiments Mainz & Troitsk of mºe =

2:2 eV , and for the future beta decay experiment KATRIN, which will reach

a sensitivity of mºe » 0:2 eV . We ¯nd that the spectrum of energy of the

electrons for this experiments it is not a®ected by the left-right asymmetry







calle jilocingo No 15

Mexico D.F



56224739 Ext 301,302

Dinamical mass generation in Quantum Electrodynamics with weak magnetic fields

We study the dynamical generation of masses for fundamental fermions in

quenched quantum electrodynamics in the presence of magnetic fields using

Schwinger-Dyson equations. We show that, contrary to the case where the

magnetic field is strong, in the weak field limit masses are generated above a

critical value of the coupoling and that this value is the same as the case

with no magnetic field. Under simplifying assumptions, we use bifurcation

theory to analytically find the value of critical coupling costant and use

this input to carry aut the numerical analysis. The findings of this

work might be relevant for processes involving dynamical properties of

fermion during the evolution of the early universe where weak magnetic

fields could be present.




Instituto de Física y Matemáticas. UMSNH


Edificio C-3. Ciudad Universitaria

Morelia, Mich.



(01) 443 3 22 35 00 Ext. 4138

(01) 443 3 22 35 00 Ext. 4144


Scalar QED at the One-loop Level

Authors: A. Bashir, Y. Concha Sánchez and L.X. Gutierrez Guerrero

Scalar Quantum Electrodynamics (SQED) is one of the simplest gauge

theories. Although fundamental scalars have not yet been observed,

several popular theoretical scenarios rely on such fields. Higgs of the

standard model is an obvious example. However, in many of its extensions,

charged scalars also arise naturally.

Moreover, electromagnetic interactions of the charged scalars are believed

to play an important role in the dynamics of inflation in the early

universe. In this work, we present one-loop evaluation of two-, three- and

four-point Green\'s functions in SQED and also study their gauge-covariance






Instituto de Ciencias Nucleares, UNAM


Prado Norte 226A int. 1, Col. Casa Blanca




722 2115351

Tsallis thermodynamics and dark matter halos

We present an alternative for the description of galactic dark matter halos

based in Tsallis thermodynamics. This proposal is statistically tested against

the current paradigm, the NFW scheme, and against observational results coming

from a resent compiled sample of disk galaxies.

"Description of charge conjugation from first principles"

Carolina Luján Peschard, Mauro Napsuciale

We show tha Dirac equation is just the eigenvalue equation for intrinsic

parity in 1/2,0)+(0,1/2) representation. We study the analogous

construction for charge conjugation operator in this irrep and obtain a

new equation which in principle is appropriate for the description of

neutral particles.


"Fermions odd space-time dimensions from first principles"

Mauro Napsuciale, Ma. Georgina Carrillo Ruiz.

In this work we wonder about the difference between the description of

fermions in arbitrary dimensions as irreps of the corresponding Poincaré

group, and their current description as irreps of the corresponding

Clifford algebra. As a first step in this direction, we study here

exhaustively the specific case d=1+2. We recalculate the irreps of the

proper orthochronous Lorentz subgroup of HLG which turn out to be of

dimension 2c+1, with c integer or semi-integer. We show that if we follow

the current definition of parity as an improper transformation, then Dirac

equation is not the covariant form of the eigenvalue equation for the

intrinsic parity operator as in the d=1+3 case. However, if we define

parity in the same way as in d=1+3 i.e. as the reversing of all the

spatial coordinates , then Dirac equation is just the covariant form of

the eigenvalue equation for intrinsic parity just like in d=1+3, in spite

of the fact that under this definition parity is a proper transformation.

An explicit construction of the charge conjugation operator, and a

non-relativistic expansion of the gauged Dirac equation shows that "spin"

has only one degree of freedom in d=1+2. Finally we show that if we define

chirality operator based on its anti-commutator with parity operator, we

can define chiral fermions, whenever we promote chirality to a true

space-time transformation, i.e. one composed of an intrinsic part and a

space-time part. It turns out that the space-time part of chirality is

precisely the improper transformation connecting the proper orthochronous

subgroup to the improper orthochronous piece i.e. the transformation

adopted as "parity" in the current literature.






Solo necesitaria beca de inscripcion pues vivo en la ciudad sede.


Fermions in Odd Space-Time Dimensions: Back to Basics

It is a well-known feature of odd space-time dimensions d that

there exist two inequivalent fundamental representations A and B of the

Dirac gamma matrices. Moreover, the parity transformation swaps the fermion

fields living in A and B. As a consequence, a parity-invariant Lagrangian

can only be constructed by incorporating both the representations. Based

upon these ideas and contrary to long-held belief, show that in addition

to a discrete exchange symmetry for the massless case, we can also define

chiral symmetry provided the Lagrangian contains fields corresponding to

both the inequivalent representations.Also study the transformation

properties of the corresponding chiral currents under parity and charge-

conjugation operations. I work explicitly in 2 + 1 dimensions and later

show how some of these ideas generalize to an arbitrary number of odd



Name : Juan Carlos Arteaga Velazquez

e-mail : jarteaga@fis.cinvestav.mx

Institution: Department of Physics, Cinvestav

Address : Av. IPN 2508, Col. Zacatenco, Del. Gustavo

A. Madero, Mexico, DF, 07000

Post Doctoral Fellow

Title: Influence of the regeneration by neutral currents

in the observable flux of upward-going muons induced

by astrophysical neutrinos

Authors: J. C. Arteaga-Velazquez and A. Zepeda

The telescopes of astrophysical high-energy neutrinos

based on the Cherenkov technique are very different

from the conventional telescopes in that the first ones

look down, to the interior of the Earth. These Cherenkov

detectors are designed to observe the upward-going

muons produced by muon neutrinos that traverse through

our planet, when they interact weakly with matter

around the detector. In order to interpret the data from

upward-going muons it is important to understand how

the neutrino flux is modified when it travels through

the Earth. Besides absorption, the neutrino flux can

be altered by other mechanisms, for example, regeneration

by means of neutral currents. In this work we explore

the effect of the regeneration through neutral currents

in the propagation of neutrinos and its influence on

the observable flux of upward-going muons for different

astrophysical and exotic models of high-energy neutrinos.



Name : Juan Carlos Arteaga Velazquez

e-mail : jarteaga@fis.cinvestav.mx

Institution: Department of Physics, Cinvestav

Address : Av. IPN 2508, Col. Zacatenco, Del. Gustavo

A. Madero, Mexico, DF, 07000

Post Doctoral Fellow

Title: Estimation of the detectable flux of astrophysical

neutrinos at the Pierre Auger observatory by means of

horizontal air showers

Authors: J. C. Arteaga-Velazquez and A. Zepeda
When the Pierre Auger Observatory is completed, it will be

able to detect ultrahigh energy astrophysical neutrinos

(E > 1 EeV) by observing the air showers of secondary

particles induced by the neutrinos in collisions

with the atmosphere on their route to the detector. In

particular, the observatory will look for those events

traveling near the horizontal direction. In this work we

calculated the detectable flux of ultrahigh energy muon

neutrinos at the Pierre Auger Observatory for several particle

physics and astrophysical models. Based on these estimates,

we found that, in some scenarios, the diffuse flux of active

galactic nuclei and topological defects have the greatest

possibility of detection of all the spectra which we analyzed and

that the muon neutrinos from the GZK cut off will be very

difficult to observe by using the above technique and only muon




*Name: Ricardo Perez Martinez

*e-mail address: rperez@fis.cinvestav.mx
*Institution: Physics Department, CINVESTAV.

*Postal address: Av. IPN 2508 Col. San Pedro Zacatenco CP 07300

*Student? If yes specify BS, MS, or PhD.

Yes. MS.
*Title: Testing nonstandard interactions in IceCube.

*Author(s): Ricardo Perez Martinez.

Arnulfo Zepeda.

Omar Miranda.
The strong evidence of a nonzero mass for neutrinos suggest

us a natural way of the existence of physics beyond the standard model

(SM). Exists a phenomenological manner to parametrize a great variety of

interactions that appear in physics beyond the SM, these parameters

currently have a wide freedom in the neutrino sector, so whatever effort

in order to bound them is of great interest. In this poster we

present and discuss the possibilities that the future detector IceCube

will have in order to improve the current bounds.







Calle Jilocingo 15, Col. Pedregal de Santo Domingo, Del. Coyoacan

Mexico D.F.



56224739 Ext. 301



Dynamical Thermal Recombination of Partons in Relativistic Heavy-Ion Collisions
AUTHORS:A. Ayala (ICN-UNAM), M. Martinez (ICN-UNAM), G. Paic (ICN-UNAM), G.

Toledo (IF-UNAM)

In relativistic heavy ion collisions, an anomalously large proton/pion ratio has

been found at intermediate values of transverse momentum. This experimental fact

has been called the \"baryon puzzle\", in the sense that if one thinks that

hadrons are produced by the fragmentation of fast moving partons, it is more

likely to produce mesons than baryons. The explanation for this result invokes

the existence of another hadron production mechanism that takes place in a

thermalized, dense parton medium and has been given the name \"thermal

recombination\". The standar recombination mechanism attempts to explain the

behavior of the proton/pion ratio assuming that thermal quarks combine

statistically within a hadron ignoring the detailed dynamics that govern such

process. In this work we present a model that incorporates the dynamics of a

dense thermal system of partons to extract the probability to create either

pions or protons as a function of the system\'s temperature.



NAME: Dominguez Jimenez Isabel

E-MAIL: isabel@nucleares.unam.mx
INSTITUTION: Instituto de Ciencias Nucleares.

Universidad Nacional Autonoma de Mexico

POSTAL ADDRESS: Circuito Extrior C.U. A.Postal 70-543 04510 Mexico D.F.
STUDENT?: YES, PhD student
TITLE: Azimuthal Correlation in pp collision
AUTHORS: Guillermo Contreras, Eleazar Cuautle, Isabel Dominguez, Guy Paic.
ABSTRACT: Partons traveling trough a medium in extreme conditions of

temperature and density, such as the created in collisions of heavy ions, lose

energy by bremstalung. This phenomenon results in suppressions of leading

partons. Experimentally, this is observed via the suppression of high pt

hadrons spectra compared to the spectra generated in proton-proton collisions

and the azimuthal correlations among particles. Since the basis of comparison

with the nucleon-nucleon data we will show the expected azimuthal correlations

obtained at 14TeV using Pythia, choosing different leading particles.



Compean Jasso

Cliffor Benjamin



Av. Manuel Nava 6, Zona Universitaria.

San Luis Potosí



(444) 8262362

(444) 8133874


Barion Spectra from a O(4) Symmetric Quark-Diquark Model with the Trigonometric

Rosen-Morse Potential

We study non-strange baryon spectra within a O(4) symmetric Quark-Diquark model.

We solve the Schrödinger equation with a trigonometric Rosen-Morse potential

(TRMP) and find energies and wave functions analytically. The TRMP is obtained

from the Eckart potential by a complexification of the argument and one expects

the wave functions of the former potential to be those of the latter, i.e. the

Jacobi polynomials but with complex parameters. However, in turns out that

the Jacobi polynomials with complex parameters are of no use in spectroscopy due

to path dependence of their orthogonality properties. Therefore, we searched and

encountered a different orthogonal polynomial solution. At first glance, these

polynomials seem not to belong to any of the orthogonal polynomial families

treated in the standard textbooks. Our model predicts correctly the observed

resonance masses and their spin- and parity degeneracy. Calculation of

electromagnetic transitions is our next goal.


"Spin > 1 fields: a new approach"

Selim Gómez , Mauro Napsuciale



In this work we propose a general formalism for the description of high

spin fields based on projection over the appropriate eigensubsapces of the

Pauli-Lubanski operator. the case of spin 2 is discussed in detail.


Name: Angel de Jesus Flores Castillo

e-mail address: shiru@ifisica.uaslp.mx

Institution: Instituto de Fisica, Universidad Autonoma de San Luis Potosi

Postal address: Manuel Nava #6, Zona Universitaria,

San Luis Potosi, SLP 78240

Student? If yes specify BS, MS, or PhD. MS Student

Title: Search for narrow baryon resonances in Xi pi

Author(s): Angel de Jesus Flores Castillo, Jurgen Engelfried, SELEX


Abstract (less than 150 words):
We report the results of a high statistics search for narrow baryon

resonances decaying to the channels Xi-pi-, Xi-pi+, aXi+pi-, and aXi+pi+.

with data from the hadroproduction experiment SELEX (Fermilab E781).



Name: Jose Luis Sanchez Lopez

e-mail address: psanchez@ifisica.uaslp.mx

Institution: Instituto de Fisica, Universidad Autonoma de San Luis Potosi

Postal address: Manuel Nava #6, Zona Universitaria,

San Luis Potosi, SLP 78240

Student? If yes specify BS, MS, or PhD. MS Student

Title: Polarization of inclusively produced Lambda's.

Author(s): Jose Luis Sanchez Lopez, Jurgen Engelfried, SELEX Collaboration

Abstract (less than 150 words):

We present the results of the measurement of the polarization

of the inclusively produced lambda by four different beams particles

(Sigma-minus, proton, pi-minus and pi-plus) incident on cooper

and carbon targets in the experiment E781 (SELEX) at Fermilab.

Two methods are used: Measurement of the acceptance and the

bias cancelling technique.



Name: Isabel Pedraza Morales

e-mail address: mpedraza@fcfm.buap.mx
Institution: Instituto de Fsica BUAP
Postal address: AP J-48, Puebla, Pue.
Student? If yes specify BS, MS, or PhD. Yes, PhD.


Author(s): L. Diaz, H. Salazar, M. I. Pedraza
The Pierre Auger Observatory for cosmic rays is sensitive to


energy neutrinos and models for new physics can be explored

by observing

neutrino interactions beyond TeV scale. A deviation of the

neutrino-nucleon cross-section from the Standard Model

expectation can be

constrained by comparing the rate for quasi-horizontal,

deeply penetrating

air showers triggered by all types of neutrinos, with the

rate for

slightly upgoing showers generated by Earth-skimming tau

neutrinos. This

can be used to test models of low-scale quantum gravity, as

well as non-perturbative electroweak instanton mediated processes.

Analysis of the efficiency of the VOA detector in the ALICE project

Carlos Pérez Lara, Alberto Gago Medina
Pontificia Universidad Católica del Perú
Gerardo Herrera
In this work, we have tested the efficiency of the VOA detector for

the ALICE project under different assumptions in the configurations of

the wavelength shifters (WLS) located within each cell, which compose

the scintillator disk. We have studied three configurations, in two of

them the WLS are on the faces parallel and perpendicular to the axis

beam, and in the last one we have used the megatile technique, in

which the WLS are embedded in the cell. For a fix number of WLS, we

have achieved a 15% of efficiency for the parallel case and a 2% of

efficiency for the perpendicular case. In the megatile case, we have

got 23% of efficiency. In addition, we have studied the optimal number

of WLS according to the area of the cell. All of these simulations

have been done using LITRANI libraries.

Name: Juan Carlos Gomez Izquierdo

e-mail address: jcarlos@fis.cinvestav.mx

Institution: Departamento de Fisica. CINVESTAV-IPN, Mexico.

Postal address: Apdo. Post. 14-740, 07000, Mexico, D.F., Mexico

Student? YES If yes specify BS, MS, or PhD.: MS
Title: "Sterile neutrinos and the solar mixing"

Author(s): Juan Carlos Gomez Izquierdo, Abdel Perez-Lorenzana

Neutrino mixing matrix appears to be close to bimaximal bixing, but for

the solar angle which is definitively smaller than 45 degres. Whereas it

seems quite easy to understand bimaximal mixings, as in models using

$L_e - L_\mu - L_\tau$ global symmetries, understanding the 12 degrees of

deviation in the observed solar angle seems less simple. We suggest that

such a deviation could be due to a light sterile netrino that mixes with

the active sector. The mass scale needed to produce the effect is shown to

be smaller than atmospheric scale, and thus, irrelevant for LSND.

Nevertheless, such a light sterile neutrino could have observable effects

that could be measure by low energy solar neutrino experiments.


Sarira Sahu

Instituto de Ciencias Nucleares, UNAM


Instituto de Ciencias Nucleares, UNAM

Mexico City

Title: Growth of magnetic field in a two component plasma


We study the electromagnetic properties of a system that consists of an

electron background and a neutrino gas that may be moving or at rest, as a

whole, relative to the background.

The photon self-energy for this system is characterized by the usual transverse

and longitudinal polarization functions,

and two additional ones which are the focus of our calculations,that give rise

to birefringence and anisotropic effects in the photon dispersion relations. We

also consider the macroscopic electrodynamic equations for this system.As an

illustration, the equations are used to discuss the evolution of a magnetic

field perturbation in such a medium.

Name: Omar Pedraza Ortega

e-mail address: omp@xanum.uam.mx


Postal address: Av. Michoacán y la Purísima, Col. Vicentina, México, D.F. 09340

Student? yes, PhD student

Title: Casimir effect in a six-dimensional vortex scenario

Authors: Omar Pedraza, Román Linares and Hugo A. Morales-Técotl

Recently Randjbar-Daemi and Shaposhnikov put forward a

4-dimensional effective QED coming from a Nielsen-Olesen vortex

solution of the abelian Higgs model with fermions coupled to gravity

in D=6. However, exploring possible physical consequences of such

an effective QED was left open. In this letter we study the

corresponding effective Casimir effect. We find that the extra

dimensions yield fifth and third inverse powers in the separation

between plates for the modified Casimir force which are in conflict

with known experiments, thus reducing the phenomenological viability

of the model.
Last Updated

October 31, 2005

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