arXiv subjects

H. B. Nielsen

Publications and source records attributed to H. B. Nielsen.

At least 37 records · Page 2Linked to original sources

arXiv2014

Standard Model and Graviweak Unification with (Super)Renormalizable Gravity. Part I: Visible and Invisible Sectors of the Universe

We develop a self-consistent $Spin(4,4)$-invariant model of the unification of gravity with weak $SU(2)$ gauge and Higgs fields in the visible and invisible sectors of our Universe. We consider a general case of the graviweak unification, including the higher-derivative super-renormalizable theory of gravity, which is a unitary, asymptotically-free and perturbatively consistent theory of the quantum gravity.

hep-ph↗

arXiv2014

On the smallness of the cosmological constant

In N=1 supergravity the scalar potential of the hidden sector may have degenerate supersymmetric (SUSY) and non-supersymmetric Minkowski vacua. In this case local SUSY in the second supersymmetric Minkowski phase can be broken dynamically. Assuming that such a second phase and the phase associated with the physical vacuum are exactly degenerate, we estimate the value of the cosmological constant. We argue that the observed value of the dark energy density can be reproduced if in the second vacuum local SUSY breaking is induced by gaugino condensation at a scale which is just slightly lower than Λ_{QCD} in the physical vacuum. The presence of a third degenerate vacuum, in which local SUSY and electroweak (EW) symmetry are broken near the Planck scale, may lead to small values of the quartic Higgs self--coupling and the corresponding beta function at the Planck scale in the phase in which we live.

hep-ph↗

arXiv2014

Cosmological constant in SUGRA models with Planck scale SUSY breaking and degenerate vacua

The empirical mass of the Higgs boson suggests small to vanishing values of the quartic Higgs self--coupling and the corresponding beta function at the Planck scale, leading to degenerate vacua. This leads us to suggest that the measured value of the cosmological constant can originate from supergravity (SUGRA) models with degenerate vacua. This scenario is realised if there are at least three exactly degenerate vacua. In the first vacuum, associated with the physical one, local supersymmetry (SUSY) is broken near the Planck scale while the breakdown of the SU(2)_W\times U(1)_Y symmetry takes place at the electroweak (EW) scale. In the second vacuum local SUSY breaking is induced by gaugino condensation at a scale which is just slightly lower than Λ_{QCD} in the physical vacuum. Finally, in the third vacuum local SUSY and EW symmetry are broken near the Planck scale.

hep-ph↗

arXiv2014

Towards a Derivation of Space

This attempt to "derive" space is part of the Random Dynamics project. The Random Dynamics philosophy is that what we observe at our low energy level can be interpreted as some Taylor tail of the physics taking place at a higher energy level, and all the concepts like numbers, space, symmetry, as well as the known physical laws, emerge from a "fundamental world machinery" being a most general, random mathematical structure. Here we concentrate on obtaining spacetime in such a Random Dynamics way. Because of quantum mechanics, we get space identified with about half the dimension of the phase space of a very extended wave packet, which we call "the Snake". In the last section we also explain locality from diffeomorphism symmetry.

hep-th↗

arXiv2013

Gravi-Weak Unification and Multiple Point Principle

We construct a model unifying gravity with weak $SU(2)$ gauge and "Higgs" scalar fields. We assume the existence of a visible and an invisible (hidden) sector of the Universe. We used the extension of Plebanski's 4-dimensional gravitational theory, in which the fundamental fields are two-forms containing tetrads, spin connections and additional auxiliary fields. Considering a $Spin(4,4)$ invariant extended Plebanski action, we recover the actions in both (visible and invisible) sectors of the Universe. After symmetry breaking of the graviweak (GW) unification, its physical constants (Newton's constants, cosmological constants, YM-couplings, etc.), are determined by a parameter $g_{uni}$ of the GW unification. It is discussed that if this "Higgs" field coming in the GW unification could be the Higgs of the Standard Model, then the idea that its vacuum value could be, according to the Multiple Point Principle, a second minimum of the Higgs field effective potential, turns out not to be viable. Then other scalar "Higgs" field, giving the inflation and axion fields, has a Planck scale expectation value, and could have a better chance of being the scalar field unified with gravity.

hep-ph↗

arXiv2013

Dimension Four Wins the Same Game as the Standard Model Group

In a previous article Don Bennett and I looked for,found and proposed a game in which the Standard Model group S(U(2)XU(3)) gets singled out as the "winner". Here I propose to extend this "game" to construct a corresponding game between different potential dimensions for space time. The idea is to formulate how the same competition as the one between the potential gauge groups would run out, if restricted to the potential Lorentz or Poincare groups achievable for different dimensions of space time d. The remarkable point is that it is the experimental dimension of space time 4 which wins. So the same function defined over Lie groups seems to single out both the gauge group and the space time dimension in nature. This seems a rather strange coincidence unless there is really some similar physics behind.

hep-ph↗

arXiv2013

Discussion on the Cosmological Vacuum Energy

The present discussion contribution is some remarks concerning and review of the proposal by one of us (C. Balazs) to explain the cosmological constant by a/the principle of entropy. Used without further comment this principle of entropy could easily lead to untrustable {\em nonlocalities}, but taking into account that the long range correlations are rather to be understood as due to initial condition set up the model for the cosmological constant being small by one of us becomes quite viable.

astro-ph.CO↗

arXiv2013

Explaining Phenomenologically Observed Space-time Flatness Requires New Fundamental Scale Physics

The phenomenologically observed flatness - or near flatness - of spacetime cannot be understood as emerging from continuum Planck (or sub-Planck) scales using known physics. Using dimensional arguments it is demonstrated that any immaginable action will lead to Christoffel symbols that are chaotic. We put forward new physics in the form of fundamental fields that spontaneously break translational invariance. Using these new fields as coordinates we define the metric in such a way that the Riemann tensor vanishes identically as a Bianchi identity. Hence the new fundamental fields define a flat space. General relativity with curvature is recovered as an effective theory at larger scales at which crystal defects in the form of disclinations come into play as the sources of curvature.

gr-qc↗

arXiv2012

Gravity and Mirror Gravity in Plebanski Formulation

We present several theories of four-dimensional gravity in the Plebanski formulation, in which the tetrads and the connections are the independent dynamical variables. We consider the relation between different versions of gravitational theories: Einstenian, dual, 'mirror' gravities and gravity with torsion. According to Plebanski's assumption, our world, in which we live, is described by the self-dual left-handed gravity. We propose that if the Mirror World exists in Nature, then the 'mirror gravity' is the right-handed anti-self-dual gravity with broken mirror parity. Considering a special version of the Riemann--Cartan space-time, which has torsion as additional geometric property, we have shown that in the Plebanski formulation the ordinary and dual sectors of gravity, as well as the gravity with torsion, are equivalent. In this context, we have also developed a 'pure connection gravity' -- a diffeomorphism-invariant gauge theory of gravity. We have calculated the partition function and the effective Lagrangian of this four-dimensional gravity and have investigated the limit of this theory at small distances.

gr-qc↗

arXiv2012

New indications of the existence of the 6 top-anti-top quark bound states in LHC experiments

It was shown: 1) that the mass of the Higgs boson discovered by LHC corresponds to the stability conditions of the SM vacua and to the Multiple Point Principle, according to which all vacua of the SM are degenerate, or almost degenerate; 2) that early predicted by authors new bound states (NBS) of the 6 top and 6 anti-top quarks ("T-fireballs"), which are formed by their intermediate interactions with the Higgs bosons, manifest themselves in the production of multijets in pp-collisions at LHC. The CMS experiment of LHC with the production of 10 jets can be explained by the production of pairs of these NBS along with the production of pairs of the top-anti-top quarks. 3) Also it was shown that the next indication of the possible existence of the NBS can be the decay $H\to γγ$, which was observed by CMS-collaboration of LHC. We have considered the contributions of the one-loop diagrams to the width $Γ_{H\to γγ}$, taking into account the contributions of the T-fireballs along the contributions of the known SM-particles.

hep-ph↗

arXiv2012

Magnetic Moment of Constituent Fermions in Strongly Interacting Matter

We investigate the magnetic moment operator for constituent fermion masses for chirally symmetric theories. Constituent fermion masses are generated through a yukawa interaction of the fermion with a scalar (or /and psuedoscalar) field via the vacuum expectation value (VEV) of the scalar (or and psuedoscalar) field. We especially consider the high baryon density $π_0$ condensed phase, in which chiral symmetry is spontaneously broken, with space varying expectation values of the $ σ$ and $π_0$ fields. This phase has a spin polarized fermi sea as the ground state. We show that there is indeed generated a macroscopic magnetization in this phase, contrary to what one would have found, if one just used a primitive phenomenological magnetic moment formula for explicit/ current fermion masses. Furthermore, this analysis reveals that the magnetization of this state goes up as the VEV, that determines the 'mass', comes down with increasing baryon density. The consequent high magnetic field that is generated will destabilize this state at a threshold density. This is important in the context of neutron stars, as such a high density state may be responsible for very high magnetic fields in the dense core of neutron stars. This could potentially be the origin of magnetars - the stars with the largest magnetic fields in the universe.

hep-ph↗

arXiv2012

The relation between the model of a crystal with defects and Plebanski's theory of gravity

In the present investigation we show that there exists a close analogy of geometry of spacetime in GR with a structure of defects in a crystal. We present the relation between the Kleinert's model of a crystal with defects and Plebanski's theory of gravity. We have considered the translational defects - dislocations, and the rotational defects - disclinations - in the 3- and 4-dimensional crystals. The 4-dimensional crystalline defects present the Riemann-Cartan spacetime which has an additional geometric property - "torsion" - connected with dislocations. The world crystal is a model for the gravitation which has a new type of gauge symmetry: the Einstein's gravitation has a zero torsion as a special gauge, while a zero connection is another equivalent gauge with nonzero torsion which corresponds to the Einstein's theory of "teleparallelism". Any intermediate choice of the gauge with nonzero connection A^{IJ}_μis also allowed. In the present investigation we show that in the Plebanski formulation the phase of gravity with torsion is equivalent to the ordinary or topological gravity, and we can exclude a torsion as a separate dynamical variable.

hep-th↗

arXiv2012

Physical Account of Weyl Anomaly from Dirac Sea

We derive the Weyl anomaly in two dimensional space-time by considering the Dirac sea regularized some negatively counted formally bosonic extra species.In fact we calculate the trace of the energy-momentum tensor of the Dirac sea in a background gravitational field. It has to be regularized, since otherwise the Dirac sea is bottomless and thus causes divergence. The new regularization method consists in adding various massive species some of which are to be counted negative in the Dirac sea.The mass term in the Lagrangian of the regularization fields have a dependence on the background gravitational field.

hep-th↗

arXiv2011

Dark Energy density in models with Split Supersymmetry and degenerate vacua

In N=1 supergravity supersymmetric (SUSY) and non-supersymmetric Minkowski vacua originating in the hidden sector can be degenerate. In the supersymmetric phase in flat Minkowski space non-perturbative supersymmetry breakdown may take place in the observable sector, inducing a non-zero and positive vacuum energy density. Assuming that such a supersymmetric phase and the phase in which we live are degenerate, we estimate the value of the cosmological constant. We argue that the observed value of the dark energy density can be reproduced in the Split-SUSY scenario of the supersymmetry breaking if the SUSY breaking scale is of order of 10^{10} GeV.

hep-ph↗

arXiv2011

An Idea of New String Field Theory - Liberating Right and Left Movers -

We develop the idea for a new string field theory of ours that was proposed earlier in a very rudimentary form in a talk in the Symposium of Tohwa University [1]. The main point is to describe the system of strings in the Universe by means of the images of the derivatives of the right and left mover parts of the 26-position vector on the strings w.r.t. tau. The major progress since the Tohwa-talks [1] is to imagine a discretization of the variables on which right and left movers respectively depend. We then observe that, by using only the descritized even-numbered sites, we can set the commutation rules for second quantization without any contradiction. In fact we can quantize the objects described by these even numbered images. A light-cone frame description of the string field theory in this way is presented.

hep-th↗

arXiv2011

Mirror World and Superstring-Inspired Hidden Sector of the Universe, Dark Matter and Dark Energy

We develop a concept of parallel existence of the ordinary (O) and hidden (H) worlds. We compare two cases: 1) when the hidden sector of the Universe is a mirror counterpart of the ordinary world, and 2) when it is a superstring-inspired shadow world described, in contrast to the mirror world, by a symmetry group (or by a chain of groups), which does not coincide with the ordinary world symmetry group. We construct a cosmological model assuming the existence of the superstring-inspired E_6 unification, broken at the early stage of the Universe to SO(10)\times U(1)_Z - in the O-world, and to SU(6)'\times SU(2)'_θ- in the H-world. As a result, we obtain the low energy symmetry group G'_SM\times SU(2)'_θin the shadow world, instead of the Standard Model group G_SM existing in the O-world. The additional non-Abelian SU(2)'_θgroup with massless gauge fields, "thetons", is responsible for dark energy. Considering a quintessence model of cosmology with an inflaton σand an axion a_θ, which is a pseudo Nambu-Goldstone boson induced by the SU(2)'_θ-group anomaly, we explain the origin of Dark Energy, Dark Matter and Ordinary Matter. In the present model we review all cosmological epochs (inflation, reheating, recombination and nucleosynthesis), and give our version of the baryogenesis. The cosmological constant problem is also briefly discussed.

hep-ph↗

arXiv2011

E6 Unification and the Hidden Sector of the Universe

A talk presents a new cosmological model with superstring-inspired $E_6$ unification, broken at the early stage of the Universe into $SO(10)\times U(1)_Z$ -- into the ordinary world, and $SU(6)'\times SU(2)'_θ$ -- into the hidden world.

hep-ph↗

arXiv2011

New Bound States of Heavy Quarks at LHC and Tevatron

The present paper is based on the assumption that heavy quarks bound states exist in the Standard Model (SM). Considering New Bound States (NBS) of top-anti-top quarks (named T-balls) we have shown that: 1) there exists the scalar 1S--bound state of $6t+6\bar t$; 2) the forces which bind the top-quarks are very strong and almost completely compensate the mass of the twelve top-anti-top-quarks in the scalar NBS; 3) such strong forces are produced by the Higgs-top-quarks interaction with a large value of the top-quark Yukawa coupling constant $g_t\simeq 1$. Theory also predicts the existence of the NBS $6t + 5\bar t$, which is a color triplet and a fermion similar to the $t'$-quark of the fourth generation. We have also considered the "b-quark-replaced" NBS, estimated the masses of the lightest fermionic NBS: $M_{NBS}\gtrsim 300$ GeV, and discussed the larger masses of T-balls. We have developed a theory of the scalar T-ball's condensate and predicted the existence of three SM phases. Searching for heavy quark bound states at the Tevatron and LHC is discussed. We have constructed the possible form-factors of T-balls, and estimated the charge multiplicity coming from the T-ball's decays.

hep-ph↗