57 research outputs found
Spread Supersymmetry
In the multiverse the scale of SUSY breaking, \tilde{m} = F_X/M_*, may scan
and environmental constraints on the dark matter density may exclude a large
range of \tilde{m} from the reheating temperature after inflation down to
values that yield a LSP mass of order a TeV. After selection effects, the
distribution for \tilde{m} may prefer larger values. A single environmental
constraint from dark matter can then lead to multi-component dark matter,
including both axions and the LSP, giving a TeV-scale LSP lighter than the
corresponding value for single-component LSP dark matter.
If SUSY breaking is mediated to the SM sector at order X^* X, only squarks,
sleptons and one Higgs doublet acquire masses of order \tilde{m}. The gravitino
mass is lighter by a factor of M_*/M_Pl and the gaugino masses are suppressed
by a further loop factor. This Spread SUSY spectrum has two versions; the
Higgsino masses are generated in one from supergravity giving a wino LSP and in
the other radiatively giving a Higgsino LSP. The environmental restriction on
dark matter fixes the LSP mass to the TeV domain, so that the squark and
slepton masses are order 10^3 TeV and 10^6 TeV in these two schemes. We study
the spectrum, dark matter and collider signals of these two versions of Spread
SUSY. The Higgs is SM-like and lighter than 145 GeV; monochromatic photons in
cosmic rays arise from dark matter annihilations in the halo; exotic short
charged tracks occur at the LHC, at least for the wino LSP; and there are the
eventual possibilities of direct detection of dark matter and detailed
exploration of the TeV-scale states at a future linear collider. Gauge coupling
unification is as in minimal SUSY theories.
If SUSY breaking is mediated at order X, a much less hierarchical spectrum
results---similar to that of the MSSM, but with the superpartner masses 1--2
orders of magnitude larger than in natural theories.Comment: 20 pages, 5 figure
Yukawa Unification and the Superpartner Mass Scale
Naturalness in supersymmetry (SUSY) is under siege by increasingly stringent
LHC constraints, but natural electroweak symmetry breaking still remains the
most powerful motivation for superpartner masses within experimental reach. If
naturalness is the wrong criterion then what determines the mass scale of the
superpartners? We motivate supersymmetry by (1) gauge coupling unification, (2)
dark matter, and (3) precision b-tau Yukawa unification. We show that for an
LSP that is a bino-Higgsino admixture, these three requirements lead to an
upper-bound on the stop and sbottom masses in the several TeV regime because
the threshold correction to the bottom mass at the superpartner scale is
required to have a particular size. For tan beta about 50, which is needed for
t-b-tau unification, the stops must be lighter than 2.8 TeV when A_t has the
opposite sign of the gluino mass, as is favored by renormalization group
scaling. For lower values of tan beta, the top and bottom squarks must be even
lighter. Yukawa unification plus dark matter implies that superpartners are
likely in reach of the LHC, after the upgrade to 14 (or 13) TeV, independent of
any considerations of naturalness. We present a model-independent, bottom-up
analysis of the SUSY parameter space that is simultaneously consistent with
Yukawa unification and the hint for m_h = 125 GeV. We study the flavor and dark
matter phenomenology that accompanies this Yukawa unification. A large portion
of the parameter space predicts that the branching fraction for B_s to mu^+
mu^- will be observed to be significantly lower than the SM value.Comment: 34 pages plus appendices, 20 figure
When Patrolmen Become Corrupted: Monitoring a Graph using Faulty Mobile Robots
International audienceA team of k mobile robots is deployed on a weighted graph whose edge weights represent distances. The robots perpetually move along the domain, represented by all points belonging to the graph edges, not exceeding their maximal speed. The robots need to patrol the graph by regularly visiting all points of the domain. In this paper, we consider a team of robots (patrolmen), at most f of which may be unreliable, i.e. they fail to comply with their patrolling duties. What algorithm should be followed so as to minimize the maximum time between successive visits of every edge point by a reliable patrolmen? The corresponding measure of efficiency of patrolling called idleness has been widely accepted in the robotics literature. We extend it to the case of untrusted patrolmen; we denote by Ifk (G) the maximum time that a point of the domain may remain unvisited by reliable patrolmen. The objective is to find patrolling strategies minimizing Ifk (G). We investigate this problem for various classes of graphs. We design optimal algorithms for line segments, which turn out to be surprisingly different from strategies for related patrolling problems proposed in the literature. We then use these results to study the case of general graphs. For Eulerian graphs G, we give an optimal patrolling strategy with idleness Ifk (G) = (f + 1)|E|/k, where |E| is the sum of the lengths of the edges of G. Further, we show the hardness of the problem of computing the idle time for three robots, at most one of which is faulty, by reduction from 3-edge-coloring of cubic graphs â a known NP-hard problem. A byproduct of our proof is the investigation of classes of graphs minimizing idle time (with respect to the total length of edges); an example of such a class is known in the literature under the name of Kotzig graphs
The KamLAND Full-Volume Calibration System
We have successfully built and operated a source deployment system for the
KamLAND detector. This system was used to position radioactive sources
throughout the delicate 1-kton liquid scintillator volume, while meeting
stringent material cleanliness, material compatibility, and safety
requirements. The calibration data obtained with this device were used to fully
characterize detector position and energy reconstruction biases. As a result,
the uncertainty in the size of the detector fiducial volume was reduced by a
factor of two. Prior to calibration with this system, the fiducial volume was
the largest source of systematic uncertainty in measuring the number of
anti-neutrinos detected by KamLAND. This paper describes the design, operation
and performance of this unique calibration system.Comment: 30 pages, 22 figures, to be submitted to JINS
The Weyl double copy from twistor space
The Weyl double copy is a procedure for relating exact solutions in biadjoint scalar, gauge and gravity theories, and relates fields in spacetime directly. Where this procedure comes from, and how general it is, have until recently remained mysterious. In this paper, we show how the current form and scope of the Weyl double copy can be derived from a certain procedure in twistor space. The new formalism shows that the Weyl double copy is more general than previously thought, applying in particular to gravity solutions with arbitrary Petrov types. We comment on how to obtain anti-self-dual as well as self-dual fields, and clarify some conceptual issues in the twistor approach
A 119-125 GeV Higgs from a string derived slice of the CMSSM
The recent experimental hints for a relatively heavy Higgs with a mass in the range 119-125 GeV favour supersymmetric scenarios with a large mixing in the stop mass matrix. It has been shown that this is possible in the constrained Minimal Super-symmetric Standard Model (CMSSM), but only for a very specific relation between the trilinear parameter and the soft scalar mass, favouring Aââââ2m for a relatively light spectrum, and sizable values of tan ÎČ. We describe here a string-derived scheme in which the first condition is automatic and the second arises as a consequence of imposing radiative EW symmetry breaking and viable neutralino dark matter in agreement with WMAP constraints. More specifically, we consider modulus dominated SUSY-breaking in Type II string compactifications and show that it leads to a very predictive CMSSM-like scheme, with small departures due to background fluxes. Imposing the above constraints leaves only one free parameter, which corresponds to an overall scale. We show that in this construction A=â3/2ââmââ2mA=â3/2mââ2m and in the allowed parameter space tan ÎČâââ38âââ41, leading to 119 GeVâ<âmhâ <â125 GeV. The recent LHCb results on BR(BsâââÎŒ+ÎŒâ) further constrain this range, leaving only the region with mhâ~â125. GeV. We determine the detectability of this model and show that it could start being probed by the LHC at 7(8) TeV with a luminosity of 5(2) fbâ1, and the whole parameter space would be accessible for 14 TeV and 25 fbâ1. Furthermore, this scenario can host a long-lived stau with the right properties to lead to catalyzed BBN. We finally argue that anthropic arguments could favour the highest value for the Higgs mass that is compatible with neutralino dark matter, i.e., mh-125 GeV
- âŠ