30,980 research outputs found
Unification of spins and charges in Grassmann space and in space of differential forms
Polynomials in Grassmann space can be used to describe all the internal
degrees of freedom of spinors, scalars and vectors, that is their spins and
charges. It was shown that K\"ahler spinors, which are polynomials of
differential forms, can be generalized to describe not only spins of spinors
but also spins of vectors as well as spins and charges of scalars, vectors and
spinors. If the space (ordinary and noncommutative) has 14 dimensions or more,
the appropriate spontaneous break of symmetry leads gravity in dimensions
to manifest in four dimensional subspace as ordinary gravity and all needed
gauge fields as well as the Yukawa couplings. Both approaches, the K\"ahler's
one (if generalized) and our, manifest four generations of massless fermions,
which are left handed SU(2) doublets and right handed SU(2) singlets. In this
talk a possible way of spontaneously broken symmetries is pointed out on the
level of canonical momentum.Comment: 26 pages, no figure
Why Nature has made a choice of one time and three space coordinates?
We propose a possible answer to one of the most exciting open questions in
physics and cosmology, that is the question why we seem to experience four-
dimensional space-time with three ordinary and one time dimensions. We have
known for more than 70 years that (elementary) particles have spin degrees of
freedom, we also know that besides spin they also have charge degrees of
freedom, both degrees of freedom in addition to the position and momentum
degrees of freedom. We may call these ''internal degrees of freedom '' the
''internal space'' and we can think of all the different particles, like quarks
and leptons, as being different internal states of the same particle. The
question then naturally arises: Is the choice of the Minkowski metric and the
four-dimensional space-time influenced by the ''internal space''?
Making assumptions (such as particles being in first approximation massless)
about the equations of motion, we argue for restrictions on the number of space
and time dimensions. (Actually the Standard model predicts and experiments
confirm that elementary particles are massless until interactions switch on
masses.)
Accepting our explanation of the space-time signature and the number of
dimensions would be a point supporting (further) the importance of the
''internal space''.Comment: 13 pages, LaTe
Fermionization, Number of Families
We investigate bosonization/fermionization for free massless fermions being
equivalent to free massless bosons with the purpose of checking and correcting
the old rule by Aratyn and one of us (H.B.F.N.) for the number of boson species
relative to the number of fermion species which is required to have
bosonization possible. An important application of such a counting of degrees
of freedom relation would be to invoke restrictions on the number of families
that could be possible under the assumption, that all the fermions in nature
are the result of fermionizing a system of boson species. Since a theory of
fundamental fermions can be accused for not being properly local because of
having anticommutativity at space like distances rather than commutation as is
more physically reasonable to require, it is in fact called for to have all
fermions arising from fermionization of bosons. To make a realistic scenario
with the fermions all coming from fermionizing some bosons we should still have
at least some not fermionized bosons and we are driven towards that being a
gravitational field, that is not fermionized. Essentially we reach the
spin-charge-families theory by one of us (N.S.M.B.) with the detail that the
number of fermion components and therefore of families get determined from what
possibilities for fermionization will finally turn out to exist. The
spin-charge-family theory has long been plagued by predicting 4 families rather
than the phenomenologically more favoured 3. Unfortunately we do not yet
understand well enough the unphysical negative norm square components in the
system of bosons that can fermionize in higher dimensions because we have no
working high dimensional case of fermionization. But suspecting they involve
gauge fields with complicated unphysical state systems the corrections from
such states could putatively improve the family number prediction.Comment: 30 pages, H.B. Nielsen presented the talk at Workshop
"What Comes Beyond the Standard Models", Bled, 09-17 of July, 201
The Majorana particles and the Majorana sea
Can one make a Majorana field theory for fermions starting from the zero mass
Weyl theory, then adding a mass term as an interaction? The answer to this
question is: yes we can. We can proceed similarly to the case of the Dirac
massive field theory. In both cases one can start from the zero mass Weyl
theory and then add a mass term as an interacting term of massless particles
with a constant (external) field. In both cases the interaction gives rise to a
field theory for a free massive fermion field. We present the procedure for the
creation of a mass term in the case of the Dirac and the Majorana field and we
look for a massive field as a superposition of massless fields.Comment: 11 pages, no figure
Simple quantum feedback of a solid-state qubit
We propose an experiment on quantum feedback control of a solid-state qubit,
which is almost within the reach of the present-day technology. Similar to the
earlier proposal, the feedback loop is used to maintain the coherent (Rabi)
oscillations in a qubit for an arbitrary long time; however, this is done in a
significantly simpler way, which requires much smaller bandwidth of the control
circuitry. The main idea is to use the quadrature components of the noisy
detector current to monitor approximately the phase of qubit oscillations.
The price for simplicity is a less-than-ideal operation: the fidelity is
limited by about 95%. The feedback loop operation can be experimentally
verified by appearance of a positive in-phase component of the detector current
relative to an external oscillating signal used for synchronization.Comment: 5 page
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