197 research outputs found
Phenomenology of the SU(3)_c X SU(3)_L X U(1)_X model with right-handed neutrinos
A phenomenological analysis of the three-family local gauge group
with right-handed neutrinos is carried
out. Instead of using the minimal scalar sector able to break the symmetry in a
proper way, we introduce an alternative set of four Higgs scalar triplets,
which combined with an anomaly-free discrete symmetry, produces a quark mass
spectrum without hierarchies in the Yukawa coupling contants. We also embed the
structure into a simple gauge group and show some conditions to achieve a low
energy gauge coupling unification, avoiding possible conflict with proton decay
bounds. By using experimental results from the CERN-LEP, SLAC linear collider
and atomic parity violation data, we update constraints on several parameters
of the model.Comment: RevTeX, 10 pages, 4 figures. v2: 13 pages. Substantial changes. New
section about RGE analysis. Experimental data updated. v3: Discussions about
bounds from unitarity violation of the CKM matrix and from FCNC included.
Accepted for publication in Eur. Phys. J.
alpha'-exact entropies for BPS and non-BPS extremal dyonic black holes in heterotic string theory from ten-dimensional supersymmetry
We calculate near-horizon solutions for four-dimensional 4-charge and
five-dimensional 3-charge black holes in heterotic string theory from the part
of the ten-dimensional tree-level effective action which is connected to
gravitational Chern-Simons term by supersymmetry. We obtain that the entropies
of large black holes exactly match the alpha'-exact statistical entropies
obtained from microstate counting (D=4) and AdS/CFT correspondence (D=5).
Especially interesting is that we obtain agreement for both BPS and non-BPS
black holes, contrary to the case of R^2-truncated (four-derivative) actions
(D-dimensional N=2 off-shell supersymmetric or Gauss-Bonnet) were used, which
give the entropies agreeing (at best) just for BPS black holes. The key
property of the solutions, which enabled us to tackle the action containing
infinite number of terms, is vanishing of the Riemann tensor \bar{R}_{MNPQ}
obtained from torsional connection defined with \bar{\Gamma} = \Gamma - H/2.
Morover, if every monomial of the remaining part of the effective action would
contain at least two Riemanns \bar{R}_{MNPQ}, it would trivially follow that
our solutions are exact solutions of the full heterotic effective action in
D=10. The above conjecture, which appeared (in this or stronger form) from time
to time in the literature, has controversial status, but is supported by the
most recent calculations of Richards (arXiv:0807.3453 [hep-th]). Agreement of
our results for the entropies with the microscopic ones supports the
conjecture. As for small black holes, our solutions in D=5 still have singular
horizons.Comment: 28 pages; v2: minor changes, references added; v3: extended
discussion on small black holes in sec. 5.4, more references added, accepted
in JHE
Effective interaction for pf-shell nuclei
An effective interaction is derived for use in the full pf basis. Starting
from a realistic G-matrix interaction, 195 two-body matrix elements and 4
single-particle energies are determined by fitting to 699 energy data in the
mass range 47 to 66. The derived interaction successfully describes various
structures of pf-shell nuclei. As examples, systematics of the energies of the
first 2+ states in the Ca, Ti, Cr, Fe, and Ni isotope chains and energy levels
of 56,57,58Ni are presented. The appearance of a new magic number 34 is seen.Comment: 5 pages, 4 figures, to be published in Phys. Rev.
Generalised quantum weakest preconditions
Generalisation of the quantum weakest precondition result of D'Hondt and
Panangaden is presented. In particular the most general notion of quantum
predicate as positive operator valued measure (POVM) is introduced. The
previously known quantum weakest precondition result has been extended to cover
the case of POVM playing the role of a quantum predicate. Additionally, our
result is valid in infinite dimension case and also holds for a quantum
programs defined as a positive but not necessary completely positive
transformations of a quantum states.Comment: 7 pages, no figures, added references, changed conten
Horizonless Rotating Solutions in -dimensional Einstein-Maxwell Gravity
We introduce two classes of rotating solutions of Einstein-Maxwell gravity in
dimensions which are asymptotically anti-de Sitter type. They have no
curvature singularity and no horizons. The first class of solutions, which has
a conic singularity yields a spacetime with a longitudinal magnetic field and
rotation parameters. We show that when one or more of the rotation
parameters are non zero, the spinning brane has a net electric charge that is
proportional to the magnitude of the rotation parameters. The second class of
solutions yields a spacetime with an angular magnetic field and
boost parameters. We find that the net electric charge of these traveling
branes with one or more nonzero boost parameters is proportional to the
magnitude of the velocity of the brane. We also use the counterterm method
inspired by AdS/CFT correspondence and calculate the conserved quantities of
the solutions. We show that the logarithmic divergencies associated to the Weyl
anomalies and matter field are zero, and the divergence of the action can
be removed by the counterterm method.Comment: 14 pages, references added, Sec. II amended, an appendix added. The
version to appear in Phys. Rev.
Towards a renormalizable standard model without fundamental Higgs scalar
We investigate the possibility of constructing a renormalizable standard
model with purely fermionic matter content. The Higgs scalar is replaced by
point-like fermionic self-interactions with couplings growing large at the
Fermi scale. An analysis of the UV behavior in the point-like approximation
reveals a variety of non-Gaussian fixed points for the fermion couplings. If
real, such fixed points would imply nonperturbative renormalizability and evade
triviality of the Higgs sector. For point-like fermionic self-interactions and
weak gauge couplings, one encounters a hierarchy problem similar to the one for
a fundamental Higgs scalar.Comment: 18 pages, 4 figure
The dynamics of quark-gluon plasma and AdS/CFT
In these pedagogical lectures, we present the techniques of the AdS/CFT
correspondence which can be applied to the study of real time dynamics of a
strongly coupled plasma system. These methods are based on solving
gravitational Einstein's equations on the string/gravity side of the AdS/CFT
correspondence. We illustrate these techniques with applications to the
boost-invariant expansion of a plasma system. We emphasize the common
underlying AdS/CFT description both in the large proper time regime where
hydrodynamic dynamics dominates, and in the small proper time regime where the
dynamics is far from equilibrium. These AdS/CFT methods provide a fascinating
arena interrelating General Relativity phenomenae with strongly coupled gauge
theory physics.Comment: 35 pages, 3 figures. Lectures at the 5th Aegean summer school, `From
gravity to thermal gauge theories: the AdS/CFT correspondence'. To appear in
the proceedings in `Lecture Notes in Physics
Toward a Quantization of Null Dust Collapse
Spherically symmetric, null dust clouds, like their time-like counterparts,
may collapse classically into black holes or naked singularities depending on
their initial conditions. We consider the Hamiltonian dynamics of the collapse
of an arbitrary distribution of null dust, expressed in terms of the physical
radius, , the null coordinates, for a collapsing cloud or for an
expanding cloud, the mass function, , of the null matter, and their
conjugate momenta. This description is obtained from the ADM description by a
Kucha\v{r}-type canonical transformation. The constraints are linear in the
canonical momenta and Dirac's constraint quantization program is implemented.
Explicit solutions the constraints are obtained for both expanding and
contracting null dust clouds with arbitrary mass functions.Comment: 10 pages, 2 figures (eps), RevTeX4. The last two sections have been
revised and corrected. To appear in Phys. Rev.
One-dimensional quantum channel and Hawking radiation of the Kerr and Kerr-Newman black holes
In this paper, we review the one-dimensional quantum channel and investigate
Hawking radiation of bosons and fermions in Kerr and Kerr-Newman black holes.
The result shows the Hawking radiation can be described by the quantum channel.
The thermal conductances are derived and related to the black holes'
temperatures.Comment: V2, 12 pages. Typo correcte
Energy and system size dependence of \phi meson production in Cu+Cu and Au+Au collisions
We study the beam-energy and system-size dependence of \phi meson production
(using the hadronic decay mode \phi -- K+K-) by comparing the new results from
Cu+Cu collisions and previously reported Au+Au collisions at \sqrt{s_NN} = 62.4
and 200 GeV measured in the STAR experiment at RHIC. Data presented are from
mid-rapidity (|y|<0.5) for 0.4 < pT < 5 GeV/c. At a given beam energy, the
transverse momentum distributions for \phi mesons are observed to be similar in
yield and shape for Cu+Cu and Au+Au colliding systems with similar average
numbers of participating nucleons. The \phi meson yields in nucleus-nucleus
collisions, normalised by the average number of participating nucleons, are
found to be enhanced relative to those from p+p collisions with a different
trend compared to strange baryons. The enhancement for \phi mesons is observed
to be higher at \sqrt{s_NN} = 200 GeV compared to 62.4 GeV. These observations
for the produced \phi(s\bar{s}) mesons clearly suggest that, at these collision
energies, the source of enhancement of strange hadrons is related to the
formation of a dense partonic medium in high energy nucleus-nucleus collisions
and cannot be alone due to canonical suppression of their production in smaller
systems.Comment: 20 pages and 5 figure
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