Scattering of very light scalar particles, off leptons

1983 ◽  
Vol 20 (1) ◽  
pp. 53-55
Author(s):  
B. R. Kim ◽  
C. Stamm
Keyword(s):  
Scalar Particles ◽  
Light Scalar

scholarly journals Density-dependent couplings and astrophysical bounds on light scalar particles

1989 ◽  
Vol 228 (2) ◽  
pp. 264-272 ◽  
Author(s):  
John Ellis ◽  
S. Kalara ◽  
K.A. Olive ◽  
C. Wetterich
Keyword(s):  
Density Dependent ◽  
Scalar Particles ◽  
Light Scalar

Gravitational effects of light scalar particles

1991 ◽  
Vol 382 ◽  
pp. 223 ◽  
Author(s):  
Thomas Helbig
Keyword(s):  
Gravitational Effects ◽  
Scalar Particles ◽  
Light Scalar

NEUTRON STARS AND SCALAR FIELDS

1993 ◽  
Vol 02 (03) ◽  
pp. 295-321 ◽  
Author(s):  
G.J. BENSON ◽  
R.G. MOORHOUSE ◽  
A.B. HENRIQUES
Keyword(s):  
Neutron Stars ◽  
Equations Of State ◽  
Scalar Particle ◽  
Scalar Fields ◽  
Nucleon Nucleon ◽  
Ideal Gas ◽  
Scalar Particles ◽  
Wide Range ◽  
Light Scalar ◽  
Urca Process

We calculate and discuss the possible consequences of the existence of light scalar particles on the properties of neutron stars. We take the mass and coupling to matter of this hypothetical scalar to be free parameters in our model and present results for a wide range of these. In highlighting the contrasting cases of scalar presence and absence, we have used two equations of state for the matter — the first being the relatively simple equation of state for an ideal gas of fermions; the second, which is more sophisticated, being based upon considerations of nucleon-nucleon interactions. Our results show that, for certain values of scalar mass and coupling, significant changes in the structure of the star can arise. We then examine how the presence of this scalar field can affect the cooling of mature neutron stars via alterations to the modified URCA process. Finally, we combine the results of our calculations with observational data on neutron stars, and compare our resulting bounds on the scalar particle coupling to those obtainable by other means.

Bounds on light scalar particles from nuclear decays

1984 ◽  
Vol 29 (3) ◽  
pp. 565-566 ◽  
Author(s):  
Nimai C. Mukhopadhyay ◽  
P. F. A. Goudsmit ◽  
Augusto Barroso
Keyword(s):  
Scalar Particles ◽  
Light Scalar

scholarly journals B decays into light scalar particles and glueball

2005 ◽  
Vol 39 (1) ◽  
pp. 71-86 ◽  
Author(s):  
P. Minkowski ◽  
W. Ochs
Keyword(s):  
B Decays ◽  
Scalar Particles ◽  
Light Scalar

LIMITS ON THE MASS OF LIGHT (PSEUDO)SCALAR PARTICLES FROM BETHE-HEITLER e+e− and μ+μ− PAIR PRODUCTION IN A PROTON-IRON BEAM DUMP EXPERIMENT

1992 ◽  
Vol 07 (16) ◽  
pp. 3835-3849 ◽  
Author(s):  
J. BLÜMLEIN ◽  
J. BRUNNER ◽  
H.J. GRABOSCH ◽  
P. LANIUS ◽  
S. NOWAK ◽  
...  
Keyword(s):  
Pair Production ◽  
Standard Theory ◽  
Positive Signal ◽  
Supersymmetric Extension ◽  
Beam Dump ◽  
Scalar Particles ◽  
The Standard Model ◽  
Light Scalar ◽  
The Masses ◽  
Pseudo Scalar

A search has been performed for weakly interacting neutral light scalar and pseudoscalar particles in a proton-iron beam dump experiment via the Bethe-Heitler process. No positive signal was observed. Limits are derived on the masses of these particles in the framework of the Standard Model and its minimal supersymmetric extension (MSSM) comparing the experimental results with expectations for Bethe-Heitler e+e− and μ+μ− pair production. The Higgs particle of the SU2L×U1 Standard Theory is excluded for masses in the range mH<0.9 MeV at 95% CL. Limits on light Higgs particles of the MSSM and Peccei-Quinn like axions are derived.

scholarly journals The core-cusp problem revisited: ULDM vs. CDM

2020 ◽  
Vol 37 ◽  
Author(s):  
Emily Kendall ◽  
Richard Easther
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Inner Core ◽  
Environmental Variability ◽  
Mass Relation ◽  
Scalar Particles ◽  
The Core ◽  
Light Scalar ◽  
Robust Tests ◽  
Halo Masses

Abstract The core-cusp problem is a widely cited motivation for the exploration of dark matter models beyond standard cold dark matter. One such alternative is ultralight dark matter (ULDM), extremely light scalar particles exhibiting wavelike properties on kiloparsec scales. Astrophysically realistic ULDM halos are expected to consist of inner solitonic cores embedded in NFW-like outer halos. The presence of the solitonic core suggests that ULDM may resolve the core-cusp discrepancy associated with pure NFW halos without recourse to baryonic physics. However, it has been demonstrated that the density of ULDM halos can exceed those of comparable NFW configurations at some radii and halo masses, apparently exacerbating the problem rather than solving it. This situation arises because, although solitonic cores are flat at their centres, they obey an inverse mass–radius scaling relationship. Meanwhile, the mass of the inner soliton increases with the total halo mass, and therefore the inner core becomes more peaked at large halo masses. We describe a parameterisation of the radial density profiles of ULDM halos that allows for environmental variability of the core–halo mass relation in order to investigate this issue in more detail. For halos up to $10^{12} {\rm M}_\odot$ , we find feasible ULDM profiles for which the central density is lower than their NFW counterparts at astrophysically accessible radii. However, comparisons to observed profiles do not strongly favour either option; both give reasonable fits to subsets of the data for some parameter choices. Consequently, we find that robust tests of the core-cusp problem in ULDM will require more comprehensive observational data and simulations that include baryonic feedback.

scholarly journals Constraints on Gravitation from Causality and Quantum Consistency

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Mark P. Hertzberg
Keyword(s):  
General Relativity ◽  
Free Fall ◽  
Companion Paper ◽  
Riemann Tensor ◽  
Effective Field ◽  
Scalar Particles ◽  
Massless Spin ◽  
Light Scalar ◽  
Higher Derivatives

We examine the role of consistency with causality and quantum mechanics in determining the properties of gravitation. We begin by examining two different classes of interacting theories of massless spin 2 particles—gravitons. One involves coupling the graviton with the lowest number of derivatives to matter, the other involves coupling the graviton with higher derivatives to matter, making use of the linearized Riemann tensor. The first class requires an infinite tower of terms for consistency, which is known to lead uniquely to general relativity. The second class only requires a finite number of terms for consistency, which appears as another class of theories of massless spin 2. We recap the causal consistency of general relativity and show how this fails in the second class for the special case of coupling to photons, exploiting related calculations in the literature. In a companion paper Hertzberg and Sandora (2017), this result is generalized to a much broader set of theories. Then, as a causal modification of general relativity, we add light scalar particles and recap the generic violation of universal free-fall they introduce and its quantum resolution. This leads to a discussion of a special type of scalar-tensor theory: the F(R) models. We show that, unlike general relativity, these models do not possess the requisite counterterms to be consistent quantum effective field theories. Together this helps to remove some of the central assumptions made in deriving general relativity.

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