Single Mass Scale Research Articles

Tabletop potentials for inflation from f(R) gravity

We show that a large class of modified gravity theories (MOG) with the Jordan-frame Lagrangian f(R) translate into scalar-field (scalaron) models with hilltop potentials in the Einstein frame. (A rare exception to this rule is provided by the Starobinsky model for which the corresponding scalaron potential is plateau-like for ϕ > 0.) We find that MOG models featuring two distinct mass scales lead to scalaron potentials that have a flattened hilltop, or tabletop. Inflationary evolution in tabletop models agrees very well with CMB observations. Tabletop potentials therefore provide a new and compelling class of MOG-based inflationary models. By contrast, MOG models with a single mass scale generally correspond to steep hilltop potentials and fail to reproduce the CMB power spectrum. Inflationary evolution in hilltop/tabletop models can proceed in two alternative directions: towards the stable point at small R describing the observable universe, or towards the asymptotic region at large R. The MOG models which we examine have several new properties including the fact that gravity can become asymptotically vanishing, with G eff → 0, at infinite or large finite values of the scalar curvature R. A universe evolving towards the asymptotically vanishing gravity region at large R will either run into a 'Big-Rip' singularity, or inflate eternally.

Emergence of Hadron Mass and Structure

Visible matter is characterised by a single mass scale; namely, the proton mass. The proton’s existence and structure are supposed to be described by quantum chromodynamics (QCD); yet, absent Higgs boson couplings, chromodynamics is scale-invariant. Thus, if the Standard Model is truly a part of the theory of Nature, then the proton mass is an emergent feature of QCD; and emergent hadron mass (EHM) must provide the basic link between theory and observation. Nonperturbative tools are necessary if such connections are to be made; and in this context, we sketch recent progress in the application of continuum Schwinger function methods to an array of related problems in hadron and particle physics. Special emphasis is given to the three pillars of EHM—namely, the running gluon mass, process-independent effective charge, and running quark mass; their role in stabilising QCD; and their measurable expressions in a diverse array of observables.

Charms of strongly interacting conformal gauge mediation

By extending a previously proposed conformal gauge mediation model, we construct a gauge-mediated SUSY breaking (GMSB) model where a SUSY-breaking scale, a messenger mass, the μ-parameter and the gravitino mass in a minimal supersymmetric (SUSY) Standard Model (MSSM) are all explained by a single mass scale, a R-symmetry breaking scale. We focus on a low scale SUSY-breaking scenario with the gravitino mass m3/2 = mathcal{O}(1)mathrm{eV} , which is free from the cosmological gravitino problem and relaxes the fine-tuning of the cosmological constant. Both the messenger and SUSY-breaking sectors are subject to a hidden strong dynamics with the conformality above the messenger mass threshold (and hence the name of the model “strongly interacting conformal gauge mediation”). In our model, the Higgs B-term is suppressed and a large tan β is predicted, resulting in the relatively light second CP-even Higgs and the CP-odd Higgs with a sizable production cross section. These Higgs bosons can be tested at future LHC experiments.

Single-scale natural SUSY

We consider the prospects for natural SUSY models consistent with current data. Recent constraints make the standard paradigm unnatural so we consider what could be a minimal extension consistent with what we now know. The most promising such scenarios extend the MSSM with new tree-level Higgs interactions that can lift its mass to at least 125 GeV and also allow for flavor-dependent soft terms so that the third generation squarks are lighter than current bounds on the first and second generation squarks. We argue that a common feature of almost all such models is the need for a new scale near 10 TeV, such as a scale of Higgsing or confinement of a new gauge group. We consider the question whether such a model can naturally derive from a single mass scale associated with supersymmetry breaking. Most such models simply postulate new scales, leaving their proximity to the scale of MSSM soft terms a mystery. This coincidence problem may be thought of as a mild tuning, analogous to the usual mu problem. We find that a single mass scale origin is challenging, but suggest that a more natural origin for such a new dynamical scale is the gravitino mass, m_{3/2}, in theories where the MSSM soft terms are a loop factor below m_{3/2}. As an example, we build a variant of the NMSSM where the singlet S is composite, and the strong dynamics leading to compositeness is triggered by masses of order m_{3/2} for some fields. Our focus is the Higgs sector, but our model is compatible with a light stop (with the other generation squarks heavy, or with R-parity violation or another mechanism to hide them from current searches). All the interesting low-energy mass scales, including linear terms for S playing a key role in EWSB, arise dynamically from the single scale m_{3/2}. However, numerical coefficients from RG effects and wavefunction factors in an extra dimension complicate the otherwise simple story.

Environment-dependent dark sector

We propose a new framework unifying cold dark matter (CDM) and Modified Newtonian Dynamics (MOND) to solve their respective problems on galactic scales and large scale structure formation. In our framework the dark matter clusters on large scales but not on galactic scales. This environment dependence of the dark matter behaviors is controlled by a vector field, which also produces the MOND effects in galaxies. We find that in this framework only a single mass scale needs to be introduced to produce the phenomena of CDM, MOND and also dark energy.

Multiloop Bubbles for hot QCD

In this article, we present analytical expansion results of two single mass scale four-loop vacuum integrals in d = 3 − 2 ϵ dimensions. After finding hypergeometric representations with half-integer coefficients, we use algorithms which we implemented in FORM to expand these in terms of nested sums.

High-precision epsilon expansions of single-mass-scale four-loop vacuum bubbles

In this article we present a high-precision evaluation of the expansions in ϵ = (4 − d)/2 of (up to) four-loop scalar vacuum master integrals, using the method of difference equations developed by S. Laporta. We cover the complete set of `QED-type' master integrals, i.e. those with a single mass scale only (i.e. mi ∊ {0,m}) and an even number of massive lines at each vertex. Furthermore, we collect all that is known analytically about four-loop `QED-type' masters, as well as about all single-mass-scale vacuum integrals at one-, two- and three-loop order.

Kinetic anomalies in addition-aggregation processes

We investigate irreversible aggregation in which monomer-monomer, monomer-cluster, and cluster-cluster reactions occur with constant but distinct rates K_{MM}, K_{MC}, and K_{CC}, respectively. The dynamics crucially depends on the ratio gamma=K_{CC}/K_{MC} and secondarily on epsilon=K_{MM}/K_{MC}. For epsilon=0 and gamma<2, there is conventional scaling in the long-time limit, with a single mass scale that grows linearly in time. For gamma >= 2, there is unusual behavior in which the concentration of clusters of mass k, c_k decays as a stretched exponential in time within a boundary layer k<k* propto t^{1-2/gamma} (k* propto ln t for gamma=2), while c_k propto t^{-2} in the bulk region k>k*. When epsilon>0, analogous behaviors emerge for gamma<2 and gamma >= 2.

Single-mass-scale diagrams: construction of a basis for the ε-expansion

Exploring the idea of Broadhurst on the “sixth root of unity” we present an ansatz for construction of a basis of transcendental numbers for the ε-expansion of single mass scale diagrams with two particle massive cut. As example, several new two- and three-loop master integrals are calculated.

Flavor-changing neutral currents in the dualized standard model

The Dualized Standard Model which gives explanations for both fermion generations and Higgs fields has already been used to calculate fermion mass and mixing parameters with success. In this paper, we extend its application to low energy FCNC effects deriving bounds for various processes in terms of one single mass scale. Using then experimental information from K_L - K_S mass difference and air showers beyond the GZK cut-off, these bounds are converted into rough, order-of-magnitude predictions. In particular, the estimates for the decay K_L \to e^\pm \mu^\mp and for the mass difference between the neutral D-mesons seem accessible to experiment in the near future.

The Decoupling Theorem in Effective Scalar Field Theory

We consider decoupling in the context of an effective quantum field theory of two scalar fields with well separated mass scales and a Z2 × Z2 symmetry. We first prove, using Wilson′s exact renormalization group equation, that the theory is renormalizable, in the same way that we showed in a previous paper that theories with a single mass scale were renormalizable. We then state and prove a decoupling theorem: at scales below the mass of the heavy particle the full theory may be approximated arbitrarily closely by an effective theory of the light particle alone, with naturalness scale the heavy particle mass. We also compare our formulation of effective field theory with the more conventional local formulation.

Light gluinos in deep inelastic scattering

We extend the standard QCD predictions, up to second order, to the scaling violation of the deep inelastic structure functions in the presence of light gluinos (supersymmetric partners of gluons). We show that these new particles give rise to scaling violations which are very close to the standard ones. Therefore present experimental data are also consistent with the existence of light gluinos of mass m λ < 10 GeV. Only more precise data would be able to conclude on their existence. All scaling violation effects observed in non-singlet and singlet structure functions are obtained with a single mass scale parameter Λ eff. We also find the gluon and gluino distributions inside the nucleon, as a function of the gluino mass m λ .

The distribution of mass in SC galaxies

view Abstract Citations (78) References (18) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The distribution of mass in SC galaxies Burstein, D. ; Rubin, V. C. ; Thonnard, N. ; Ford, W. K., Jr. Abstract For a sample of 21 Sc galaxies ranging from very low to very high luminosity, we have previously presented rotational velocities across ∼83% of the galaxy isophotal radius, R25. We now analyze the mass distributions for this same sample, and show that for all galaxies, the mass distribution has a single unique form, when the masses are each scaled by a mass scale length, Rm. Unlike luminosity scale lengths which are larger for more luminous (larger) galaxies, mass scale lengths are smaller for galaxies of high luminosity. As normalized here (the radius encompassing a mass of 1010 Msun), Rm is near 4 kpc for a low luminosity Sc and is near 1.5 kpc for a high luminosity Sc. A low luminosity Sc contains a single mass scale length, a high luminosity Sc contains many tens of scale lengths within its isophotal radius. At similar multiples of their scale lengths, all Sc's have equal interior masses. The form of the characteristic mass curve implies that rotation curves are still rising slightly at radii of many scale lengths, V ∝ r0.1 or r0.2, and local density falls off slower than 1/r2 (ρ ∝ r-1.7). We conclude that the rotational velocities remain high at large nuclear distances due to the presence of significant nonluminous mass at large radii. Correlations between integral mass, luminosity, mass scale length, isophotal radius, and velocity at the isophotal radius are determined and discussed. The correlation of luminosity with V(R25)) is as steep as that found in the infrared. The ratio of mass to luminosity interior to the isophotal radius is independent of luminosity and equals 3.0 ± 0.3 for Sc galaxies. Publication: The Astrophysical Journal Pub Date: February 1982 DOI: 10.1086/159611 Bibcode: 1982ApJ...253...70B Keywords: Galactic Rotation; Mass Distribution; Mass To Light Ratios; Spiral Galaxies; Astronomical Photometry; Galactic Radiation; Isophotes; Luminous Intensity; Stellar Mass; Astrophysics full text sources ADS | data products NED (20)