122186179
Symmetry Breaking by Wilson Loop Elements in String Theories and Rescaling of Gauge Coupling Constants
Abstract It is found that there exists nontrivial rescaling of gauge coupling constants at the compactification scale by the Wilson-loop elements in the heterotic string theory. This phenomenon appears at the string loop level, and the result modifies the previous phenomenological analysis of sin 2 θ w .
14574575
Effective Gauss-Bonnet interaction in Randall-Sundrum compactification
The effective gravitational interaction below the Planck scale in the Randall-Sundrum world is shown to be the Gauss-Bonnet term. In this theory we find that there exists another static solution with a positive bulk cosmological constant. Also, there exist solutions for a positive visible sector cosmological constant, which is needed for a later Friedmann-Robertson-Walker universe.
119883211
Conflicts between B-violating phenomena in supergravity models
Abstract We show that there is an incompatibility between matter stability and cosmological baryon production in standard N = 1 supergravity models. This discrepancy emerges from the bound on the reheating temperature T rh ⩽ 10 10 GeV which comes from the restriction on the gravitino decay after inflation. Some weird possibilities to bypass the controversy are also analyzed.
15739165
SO(10)-like Superstring Standard Model with R-parity from the Heterotic String
We construct a supersymmetric standard model in the context of the Z_{12-I} orbifold compactification of the E_8 x E_8' heterotic string theory. The gauge group is SU(3)_c x SU(2)_L x U(1)_Y x U(1)^4 x [SO(10) x U(1)^3]' with sin^2\theta_W = 3/8. We obtain three families of SO(10) spinor-like chiral matter states, and Higgs doublets. All other extra states are exactly vector-like under the standard model gauge symmetry. There are numerous standard model singlets, many of which get VEVs such that only the standard model gauge symmetry survives and desired Yukawa couplings can be generated at lower energies. In particular, all vector-like exotic states achieve superheavy masses and the R-parity can be preserved.
18138135
Neutrino masses from discrete gauge symmetries
Abstract We investigate a model with an extra Z 2 gauge symmetry in the Standard Model. The symmetry gives a structure to the mass matrix for the neutrinos. With two extra Higgs singlets and two extra singlet right-handed neutrinos we can build a model that fits the requirements of the MSW solution of the Solar neutrino problem. With a third singlet right-handed neutrino it is also possible to have a 10 eV neutrino.
119316975
GMSB at a stable vacuum and MSSM without exotics from heterotic string
Abstract We show that it is possible to introduce the confining hidden sector gauge group SU ( 5 ) ′ with the chiral matter 10 0 ′ plus 5 ¯ 0 ′ , which are neutral under the standard model gauge group, toward a gauge mediated supersymmetry breaking (GMSB) in a Z 12 − I orbifold compactification of E 8 × E 8 ′ heterotic string. Three families of MSSM result without exotics. We also find a desirable matter parity P (or R-parity) assignment. We note that this model contains the spectrum of the Lee–Weinberg model which has a nice solution of the μ problem.
119212887
Elliptic genus of E-strings
A bstractWe study a family of 2d N=0,4$$ \mathcal{N}=\left(0,\ 4\right) $$ gauge theories which describes at low energy the dynamics of E-strings, the M2-branes suspended between a pair of M5 and M9 branes. The gauge theory is engineered using a duality with type IIA theory, leading to the D2-branes suspended between an NS5-brane and 8 D8-branes on an O8-plane. We compute the elliptic genus of this family of theories, and find agreement with the known results for single and two E-strings. The partition function can in principle be computed for arbitrary number of E-strings, and we compute them explicitly for low numbers. We test our predictions against the partially known results from topological strings, as well as from the instanton calculus of 5d Sp(1) gauge theory. Given the relation to topological strings, our computation provides the all genus partition function of the refined topological strings on the canonical bundle over 12K3$$ \frac{1}{2}K3 $$.
118542331
A thermal infrared imaging study of very low mass, wide-separation brown dwarf companions to upper scorpius stars: Constraining circumstellar environments
We present a 3-5 μm LBT/MMT adaptive optics imaging study of three Upper Scorpius stars with brown dwarf (BD) companions with very low masses/mass ratios (M BD <25 M Jup; M BD/M 1%-2%) and wide separations (300-700 AU): GSC 06214, 1RXS 1609, and HIP 78530. We combine these new thermal IR data with existing 1-4 μm and 24 μm photometry to constrain the properties of the BDs and identify evidence for circumprimary/circumsecondary disks in these unusual systems. We confirm that GSC 06214B is surrounded by a disk, further showing that this disk produces a broadband IR excess due to small dust near the dust sublimation radius. An unresolved 24 μm excess in the system may be explained by the contribution from this disk. 1RXS 1609B exhibits no 3-4 μm excess, nor does its primary; however, the system as a whole has a modest 24 μm excess, which may come from warm dust around the primary and/or BD. Neither object in the HIP 78530 system exhibits near- to mid-IR excesses. We additionally find that the 1-4 μm colors of HIP 78530B match a spectral type of M3 ± 2, inconsistent with the M8 spectral type assigned based on its near-IR spectrum, indicating that it may be a low-mass star rather than a BD. We present new upper limits on additional low-mass companions in the system (<5 M Jup beyond 175 AU). Finally, we examine the utility of circumsecondary disks as probes of the formation histories of wide BD companions, finding that the presence of a disk may disfavor BD formation near the primary with subsequent outward scattering.
119245195
CMB map derived from the WMAP data through harmonic internal linear combination
We are presenting an internal linear combination CMB map, in which the foreground is reduced through harmonic variance minimization. We have derived our method by converting a general form of pixel-space approach into spherical harmonic space, maintaining full correspondence. By working in spherical harmonic space, spatial variability of linear weights is incorporated in a self-contained manner and our linear weights are continuous functions of position over the entire sky. The full correspondence to pixel-space approach enables straightforward physical interpretation on our approach. In variance minimization of a linear combination map, the existence of a cross term between residual foregrounds and CMB makes the linear combination of minimum variance differ from that of minimum foreground. We have developed an iterative foreground reduction method, where perturbative correction is made for the cross term. Our CMB map derived from the WMAP data is in better agreement with the WMAP best-fit {lambda}CDM model than the WMAP team's internal linear combination map. We find that our method's capacity to clean foreground is limited by the availability of enough spherical harmonic coefficients of good signal-to-noise ratio.
54918406
Light stop searches at the LHC with monojet events
We consider light top squarks (stops) in the minimal supersymmetric Standard Model at the Large Hadron Collider. Here, we assume that the lightest neutralino is the lightest supersymmetric particle (LSP) and the lighter stop is the next-to-LSP. Stop pair production is difficult to probe at the Large Hadron Collider for small stop-LSP mass splitting. It has been shown previously that even in this case stop detection is possible if one considers stop pair production in association with one hard jet. We reconsider this supersymmetric monojet signature and go beyond previous works by including the full Standard Model background and optimizing the cuts, working at the hadron level and including detector effects. As a result, a larger portion of the stop-LSP mass plane becomes accessible to monojet searches.
118440632
Instantons on the 5-sphere and M5-branes
We calculate the partition functions of supersymmetric gauge theories on S^5, which acquire non-perturbative contributions from instanton loops wrapping its Hopf fiber. The instantons on the CP^2 base equivariantly localize to 3 fixed points of SU(3) Cartans. Using our results, we study the index of the 6d (2,0) theory. We first study the partition functions of maximal SYM with AD(E) gauge groups, which agree with the gravity dual indices on AdS_7 in the large N limits. We also show that the most general partition function of the Abelian theory agrees with the index for a free 6d tensor supermultiplet. We explain possible ambiguities in our 5d approach, role of maximal SUSY, and the Wilson loops on S^5 dual to M2-brane Wilson surfaces in AdS_7.