275 research outputs found
The Standard Model on Non-Commutative Space-Time
We consider the Standard Model on a non-commutative space and expand the
action in the non-commutativity parameter theta. No new particles are
introduced, the structure group is SU(3) x SU(2) x U(1). We derive the leading
order action. At zeroth order the action coincides with the ordinary Standard
Model. At leading order in theta we find new vertices which are absent in the
Standard Model on commutative space-time. The most striking features are
couplings between quarks, gluons and electroweak bosons and many new vertices
in the charged and neutral currents. We find that parity is violated in
non-commutative QCD. The Higgs mechanism can be applied. QED is not deformed in
the minimal version of the NCSM to the order considered.Comment: 28 pages, v3: typos corrected, new appendix on alternative kinetic
terms for gauge bosons; v4: typos correcte
Three waves for quantum gravity
Using effective field theoretical methods, we show that besides the already observed gravitational waves, quantum gravity predicts two further massive classical fields leading to two new massive waves. We set a limit on the masses of these new modes using data from the E¨ot-Wash experiment. We point out that the existence of these new states is a model independent prediction of quantum gravity. We then explain how these new classical fields could impact astrophysical processes and in particular the binary inspirals of neutron stars or black holes. We calculate the emission rate of these new states in binary inspirals astrophysical processes
Quantum Black Holes from Cosmic Rays
We investigate the possibility for cosmic ray experiments to discover
non-thermal small black holes with masses in the TeV range. Such black holes
would result due to the impact between ultra high energy cosmic rays or
neutrinos with nuclei from the upper atmosphere and decay instantaneously. They
could be produced copiously if the Planck scale is in the few TeV region. As
their masses are close to the Planck scale, these holes would typically decay
into two particles emitted back-to-back. Depending on the angles between the
emitted particles with respect to the center of mass direction of motion, it is
possible for the simultaneous showers to be measured by the detectors.Comment: 6 pages, 3 figure
Comment on triple gauge boson interactions in the non-commutative electroweak sector
In this comment we present an analysis of electroweak neutral triple gauge
boson couplings projected out of the gauge sector of the extended
non-commutative standard model. A brief overview of the current experimental
situation is given.Comment: 4 page
The Standard Model on Non-Commutative Space-Time: Electroweak Currents and Higgs Sector
In this article we review the electroweak charged and neutral currents in the
Non-Commutative Standard Model (NCSM) and compute the Higgs and Yukawa parts of
the NCSM action. With the aim to make the NCSM accessible to phenomenological
considerations, all relevant expressions are given in terms of physical fields
and Feynman rules are provided.Comment: 33 pages, axodraw.sty; shortened, comments and references added,
version to appear in EPJ
Non-Commutative GUTs, Standard Model and C,P,T properties from Seiberg-Witten map
Noncommutative generalizations of Yang-Mills theories using Seiberg-Witten
map are in general not unique. We study these ambiguities and see that SO(10)
GUT, at first order in the noncommutativity parameter \theta, is unique and
therefore is a truly unified theory, while SU(5) is not. We then present the
noncommutative Standard Model compatible with SO(10) GUT. We next study the
reality, hermiticity and C,P,T properties of the Seiberg-Witten map and of
these noncommutative actions at all orders in \theta. This allows to compare
the Standard Model discussed in [5] with the present GUT inspired one.Comment: 9 pages. Presented at the Balkan Workshop 2003, Vrnjacka Banja,
29.8-2.9.2003 and at the 9th Adriatic Meeting, Dubrovnik, 4-14.9.200
Absolutely stable proton and lowering the gauge unification scale
A unified model is constructed, based on flipped SU(5) in which the proton is absolutely stable. The model requires the existence of new leptons with masses of order the weak scale. The possibility that the unification scale could be extremely low is discussed
Minimum black hole mass from colliding Gaussian packets
We study the formation of a black hole in the collision of two Gaussian
packets. Rather than following their dynamical evolution in details, we assume
a horizon forms when the mass function for the two packets becomes larger than
half the flat areal radius, as it would occur in a spherically symmetric
geometry. This simple approximation allows us to determine the existence of a
minimum black hole mass solely related to the width of the packets. We then
comment on the possible physical implications, both in classical and quantum
physics, and models with extra spatial dimensions.Comment: 11 pages, 4 figure
Quantum gravitational corrections to a star metric and the black hole limit
In this paper we consider the full set of quantum gravitational corrections to a star metric to second order in curvature. As we use an effective field theoretical approach, these corrections apply to any model of quantum gravity that is based on general coordinate invariance. We then discuss the black hole limit and identify an interesting phenomenon which could shed some light on the nature of astrophysical black holes: while star metrics receive corrections at second order in curvature, vacuum solutions such as black hole metrics do not. What happens to these corrections when a star collapses
A review of Quantum Gravity at the Large Hadron Collider
The aim of this article is to review the recent developments in the
phenomenology of quantum gravity at the Large Hadron Collider. We shall pay
special attention to four-dimensional models which are able to lower the
reduced Planck mass to the TeV region and compare them to models with a large
extra-dimensional volume. We then turn our attention to reviewing the emission
of gravitons (massless or massive) at the LHC and to the production of small
quantum black holes.Comment: 32 pages, invited revie
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