45 research outputs found
Nuclear and partonic dynamics in the EMC effect
It has been recently confirmed that the magnitude of the EMC effect measured
in electron deep inelastic scattering is linearly related to the Short Range
Correlation scaling factor obtained from electron inclusive scattering. By
using a -rescaling approach we are able to understand the interplay between
the quark-gluon and hadronic degrees of freedom in the discussion of the EMC
effect.Comment: 5 pages, 6 figures, 2 table. We have incorporated SLAC data and
redone the calculation with the newest ROOT 5.3
Venus Atmosphere Profile from a Maximum Entropy Principle
The variational method with constraints recently developed by Verkley and
Gerkema to describe maximum-entropy atmospheric profiles is generalized to
ideal gases but with temperature-dependent specific heats. In so doing, an
extended and non standard potential temperature is introduced that is well
suited for tackling the problem under consideration. This new formalism is
successfully applied to the atmosphere of Venus. Three well defined regions
emerge in this atmosphere up to a height of from the surface: the
lowest one up to about is adiabatic, a transition layer located at the
height of the cloud deck and finally a third region which is practically
isothermal.Comment: 6 pages, 3 figure
Hunting long-lived gluinos at the Pierre Auger Observatory
A ps version of the paper with high resolution figures is available at: http://www.hep.physics.neu.edu/staff/doqui/rhadron_highres.psEventual signals of split sypersymmetry in cosmic ray physics are analyzed in detail. The study focusses particularly on quasi-stable colorless R-hadrons originating through confinement of long-lived gluinos (with quarks, anti-quarks, and gluons) produced in pp collisions at astrophysical sources. Because of parton density requirements, the gluino has a momentum which is considerable smaller than the energy of the primary proton, and so production of heavy (mass ~ 500 GeV) R-hadrons requires powerful cosmic ray engines able to accelerate particles up to extreme energies, somewhat above 10^{13.6} GeV. Using a realistic Monte Carlo simulation with the AIRES engine, we study the main characteristics of the air showers triggered when one of these exotic hadrons impinges on a stationary nucleon of the Earth atmosphere. We show that R-hadron air showers present clear differences with respect to those initiated by standard particles. We use this shower characteristics to construct observables which may be used to distinguish long-lived gluinos at the Pierre Auger Observatory.Peer reviewe
Through the looking-glass with ALICE into the quark-gluon plasma: A new test for hadronic interaction models used in air shower simulations
Recently, the ALICE Collaboration reported an enhancement of the yield ratio of strange and multi-strange hadrons to charged pions as a function of multiplicity at mid-rapidity in proton-proton, proton-lead, lead-lead, and xenon-xenon scattering. ALICE observations provide a strong indication that a quark-gluon plasma is partly formed in high multiplicity events of both small and large colliding systems. Motivated by ALICE’s results, we propose a new test for hadronic interaction models used for analyzing ultra-highenergy-cosmic-ray (UHECR) collisions with air nuclei. The test is grounded in the almost equal columnenergy density in UHECR-air collisions and lead-lead collisions at the LHC. We applied the test to postLHC event generators describing hadronic phenomena of UHECR scattering and show that these QCD Monte Carlo-based codes must be retuned to accommodate the strangeness enhancement relative to pions observed in LHC data.Fil: Anchordoqui, Luis A.. American Museum of Natural History; Estados Unidos. City University of New York; Estados UnidosFil: García Canal, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Sciutto, Sergio Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Soriano, Jorge F.. City University of New York; Estados Unido
Spin Dependence of Heavy Quark Fragmentation
We propose that the non-perturbative fragmentation functions describing the
transition from a heavy quark to a heavy meson is proportional to the square of
the produced meson wave function at the origin. We analyze the effects of this
proposal on the number of pseudoscalar mesons compared to the number of vector
mesons produced and find a good agreement with experimental data. Finally, we
discuss further experimental checks for our hypothesis.Comment: 4 page
Quark masses without Yukawa hierarchies
A model based on the local gauge group SU(3)c⊗SU(3)L⊗U(1)X without particles with exotic electric charges is shown to be able to provide the quark mass spectrum and their mixing, by means of universal see-saw mechanisms, avoiding a hierarchy in the Yukawa coupling constants.Facultad de Ciencias Exacta
Analytic structure of the S-matrix for singular quantum mechanics
The analytic structure of the S-matrix of singular quantum mechanics is examined within a multichannel framework, with primary focus on its dependence with respect to a parameter (Ω) that determines the boundary conditions. Specifically, a characterization is given in terms of salient mathematical and physical properties governing its behavior. These properties involve unitarity and associated current-conserving Wronskian relations, time-reversal invariance, and Blaschke factorization. The approach leads to an interpretation of effective nonunitary solutions in singular quantum mechanics and their determination from the unitary family.Fil: Camblong, Horacio E.. University of San Francisco; Estados UnidosFil: Epele, Luis Nicolas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Física. Laboratorio de Física Teórica; ArgentinaFil: Fanchiotti, Huner. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Física. Laboratorio de Física Teórica; ArgentinaFil: García Canal, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Física. Laboratorio de Física Teórica; Argentin
On Charge Quantization and Abelian Gauge Horizontal Symmetries
Under the assumption that there exists a local gauge horizontal symmetry GH wich allows only for a top quark mass at tree level, we look for the constraints that charge quatization and the family structure of the standard model imposes on that symmetry.Facultad de Ciencias Exacta
Effective Field Theory Program for Conformal Quantum Anomalies
The emergence of conformal states is established for any problem involving a
domain of scales where the long-range, SO(2,1) conformally invariant
interaction is applicable. Whenever a clear-cut separation of ultraviolet and
infrared cutoffs is in place, this renormalization mechanism produces binding
in the strong-coupling regime. A realization of this phenomenon, in the form of
dipole-bound anions, is discussed.Comment: 15 pages. Expanded, with additional calculational details. To be
published in Phys. Rev.