REALISTIC HIERARCHIES FROM THE SUPERSTRING

1989 ◽  
Vol 04 (02) ◽  
pp. 411-426 ◽  
Author(s):  
G. D. COUGHLAN
Keyword(s):  
Field Theory ◽  
Cosmological Constant ◽  
Parameter Space ◽  
Low Energy ◽  
Heterotic String ◽  
Large Region ◽  
World Sheet ◽  
Dimensional Theory ◽  
Vacuum States ◽  
Large Hierarchy

A simple phenomenological parametrization of the four-dimensional field theory arising from compactification of the ten-dimensional heterotic string is considered. Possible vacuum states of the four-dimensional theory are examined in the context of the "model" low-energy Lagrangian proposed by Witten. A large hierarchy between MP and m3/2 arises naturally for a large region of parameter space, with the compactification scale typically 0(1 − 10−2)and a vanishing cosmological constant. The presence of E6 singlet superfields with large nonperturbative masses (coming from world-sheet instantons) can drastically alter the hierarchy in certain cases, but nonetheless leads to acceptable low-energy phenomenology.

CLASSICAL GHOSTS AND THE COSMOLOGICAL CONSTANT

2004 ◽  
Vol 19 (31) ◽  
pp. 5317-5324
Author(s):  
T. HIRAYAMA
Keyword(s):  
Energy Density ◽  
Cosmological Constant ◽  
Parameter Space ◽  
Large Time ◽  
Finite Energy ◽  
Negative Energy ◽  
Scale Factor ◽  
Large Region ◽  
Unstable Behavior ◽  
Negative Cosmological Constant

For a large region of parameter space involving the cosmological constant and mass parameters, we discuss spacetime solutions that are effectively Minkowskian on large time and distance scales. A negative energy fluid is involved, resulting in a scale factor oscillating about a constant, with a frequency determined by the size of a negative cosmological constant. Gravity itself induces a coupling between the ghost-like and normal fields, and we find that this results in stochastic rather than unstable behavior. Ghosts could also allow for the existence of Lorentz invariant fluctuating solutions of finite energy density.

scholarly journals CHARGING INTERACTING ROTATING BLACK HOLES IN HETEROTIC STRING THEORY

2004 ◽  
Vol 19 (30) ◽  
pp. 2299-2315 ◽  
Author(s):  
ALFREDO HERRERA-AGUILAR
Keyword(s):  
Field Theory ◽  
Black Holes ◽  
String Theory ◽  
Effective Field Theory ◽  
Effective Field ◽  
Low Energy ◽  
Heterotic String ◽  
Target Space ◽  
Heterotic String Theory ◽  
Rotating Black Holes

We present a formulation of the stationary bosonic string sector of the whole toroidally compactified effective field theory of the heterotic string as a double Ernst system which, in the framework of general relativity describes, in particular, a pair of interacting spinning black holes; however, in the framework of low-energy string theory the double Ernst system can in particular be interpreted as the rotating field configuration of two interacting sources of black hole type coupled to dilaton and Kalb–Ramond fields. We clarify the rotating character of the Btφ-component of the antisymmetric tensor field of Kalb–Ramond and discuss on its possible torsion nature. We also recall the fact that the double Ernst system possesses a discrete symmetry which is used to relate physically different string vacua. Therefore we apply the normalized Harrison transformation (a charging symmetry which acts on the target space of the low-energy heterotic string theory preserving the asymptotics of the transformed fields and endowing them with multiple electromagnetic charges) on a generic solution of the double Ernst system and compute the generated field configurations for the 4-D effective field theory of the heterotic string. This transformation generates the U (1)n vector field content of the whole low-energy heterotic string spectrum and gives rise to a pair of interacting rotating black holes endowed with dilaton, Kalb–Ramond and multiple electromagnetic fields where the charge vectors are orthogonal to each other.

COSET SPACES AS ALTERNATIVES TO CALABI-YAU SPACES IN THE PRESENCE OF GAUGINO CONDENSATION

1987 ◽  
Vol 02 (03) ◽  
pp. 797-829 ◽  
Author(s):  
T. R. GOVINDARAJAN ◽  
ANJAN S. JOSHIPURA ◽  
SAURABH D. RINDANI ◽  
UTPAL SARKAR
Keyword(s):  
Field Theory ◽  
Symmetry Group ◽  
Index Theorem ◽  
Low Energy ◽  
Heterotic String ◽  
Gauge Fields ◽  
Specific Reference ◽  
Background Value ◽  
Super Symmetry ◽  
Coset Spaces

Compactification of the field-theory limit of the E8 × E′8 heterotic string on six-dimensional coset manifolds is discussed, with specific reference to maintaining four-dimensional super-symmetry. By choosing a torsion proportional to the background value of the three-index field Hmnp occurring in the theory it is possible to satisfy the condition of SU(3) holonomy necessary for supersymmetry. However, in all cases considered, it is found impossible to satisfy all the remaining conditions for supersymmetry. If gaugino condensation is assumed to occur, it is possible to preserve supersymmetry satisfying all the modified requirements of supersymmetry for the spaces SU (3)/ U (1) × U (1), G 2/ SU (3) and SO (5)/ SU (2) × U (1). The question of chiral fermions is examined in these cases using the Atiyah-Singer index theorem. Background gauge fields, which correspond to different numbers of generations of chiral fermions, are constructed explicitly. In all these cases the low-energy symmetry group is E6 × E′8.

scholarly journals Flavour Anomalies in a U(1) SUSY Extension of the SM

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 191
Author(s):  
Alexander Bednyakov ◽  
Alfiia Mukhaeva
Keyword(s):  
Standard Model ◽  
Parameter Space ◽  
Gauge Boson ◽  
New Physics ◽  
Low Energy ◽  
Effective Theory ◽  
The Standard Model ◽  
Meson Mixing ◽  
Additional Anomaly ◽  
Lepton Flavour

Flavour anomalies have attracted a lot of attention over recent years as they provide unique hints for possible New Physics. Here, we consider a supersymmetric (SUSY) extension of the Standard Model (SM) with an additional anomaly-free gauge U(1) group. The key feature of our model is the particular choice of non-universal charges to the gauge boson Z′, which not only allows a relaxation of the flavour discrepancies but, contrary to previous studies, can reproduce the SM mixing matrices both in the quark and lepton sectors. We pay special attention to the latter and explicitly enumerate all parameters relevant for our calculation in the low-energy effective theory. We find regions in the parameter space that satisfy experimental constraints on meson mixing and LHC Z′ searches and can alleviate the flavour anomalies. In addition, we also discuss the predictions for lepton-flavour violating decays B+→K+μτ and B+→K+eτ.

scholarly journals Bounding f(R) gravity by particle production rate

2016 ◽  
Vol 25 (04) ◽  
pp. 1630010 ◽  
Author(s):  
Salvatore Capozziello ◽  
Orlando Luongo ◽  
Mariacristina Paolella
Keyword(s):  
Field Theory ◽  
Particle Production ◽  
High Redshift ◽  
Dark Side ◽  
Quantum Field ◽  
Quantum Vacuum ◽  
Vacuum States ◽  
Text Model ◽  
Free Parameters ◽  
The Given

Several models of [Formula: see text] gravity have been proposed in order to address the dark side problem in cosmology. However, these models should be constrained also at ultraviolet scales in order to achieve some correct fundamental interpretation. Here, we analyze this possibility comparing quantum vacuum states in given [Formula: see text] cosmological backgrounds. Specifically, we compare the Bogolubov transformations associated to different vacuum states for some [Formula: see text] models. The procedure consists in fixing the [Formula: see text] free parameters by requiring that the Bogolubov coefficients can be correspondingly minimized to be in agreement with both high redshift observations and quantum field theory predictions. In such a way, the particle production is related to the value of the Hubble parameter and then to the given [Formula: see text] model. The approach is developed in both metric and Palatini formalism.

scholarly journals Effective Field Theory, Black Holes, and the Cosmological Constant

1999 ◽  
Vol 82 (25) ◽  
pp. 4971-4974 ◽  
Author(s):  
Andrew G. Cohen ◽  
David B. Kaplan ◽  
Ann E. Nelson
Keyword(s):  
Field Theory ◽  
Black Holes ◽  
Cosmological Constant ◽  
Effective Field Theory ◽  
Effective Field

Heuristic determination of the cosmological constant

2021 ◽  
pp. 2150114
Author(s):  
Manuel Urueña Palomo ◽  
Fernando Pérez Lara
Keyword(s):  
Field Theory ◽  
Energy Density ◽  
Cosmological Constant ◽  
Accelerated Expansion ◽  
Fundamental Constants ◽  
Quantum Field ◽  
Brute Force ◽  
Expansion Of The Universe ◽  
The Universe

The vacuum catastrophe results from the disagreement between the theoretical value of the energy density of the vacuum in quantum field theory and the estimated one observed in cosmology. In a similar attempt in which the ultraviolet catastrophe was solved, we search for the value of the cosmological constant by brute-force through computation. We explore combinations of the fundamental constants in physics performing a dimensional analysis, in search of an equation resulting in the measured energy density of the vacuum or cosmological constant that is assumed to cause the accelerated expansion of the universe.

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