Search results for "Strings"

Constraints on Cosmic Strings Using Data from the Third Advanced LIGO–Virgo Observing Run

2021

We search for gravitational-wave signals produced by cosmic strings in the Advanced LIGO and Virgo full O3 data set. Search results are presented for gravitational waves produced by cosmic string loop features such as cusps, kinks and, for the first time, kink-kink collisions.cA template-based search for short-duration transient signals does not yield a detection. We also use the stochastic gravitational-wave background energy density upper limits derived from the O3 data to constrain the cosmic string tension, $G\mu$, as a function of the number of kinks, or the number of cusps, for two cosmic string loop distribution models.cAdditionally, we develop and test a third model which interpolat…

Intersecting Defects and Supergroup Gauge Theory

2021

Journal of physics / A 54(43), 435401 (2021). doi:10.1088/1751-8121/ac2716

Modular fluxes, elliptic genera, and weak gravity conjectures in four dimensions

2019

We analyse the Weak Gravity Conjecture for chiral four-dimensional F-theory compactifications with N=1 supersymmetry. Extending our previous work on nearly tensionless heterotic strings in six dimensions, we show that under certain assumptions a tower of asymptotically massless states arises in the limit of vanishing coupling of a U(1) gauge symmetry coupled to gravity. This tower contains super-extremal states whose charge-to-mass ratios are larger than those of certain extremal dilatonic Reissner-Nordstrom black holes, precisely as required by the Weak Gravity Conjecture. Unlike in six dimensions, the tower of super-extremal states does not always populate a charge sub-lattice. The main t…

Instability of black holes in massive gravity

2013

We show that linear perturbations around the simplest black hole solution of massive bi-gravity theories, the bi-Schwarzschild solution, exhibit an unstable mode featuring the Gregory-Laflamme instability of higher dimensional black strings. The result is obtained for the massive gravity theory which is free from the Boulware-Deser ghost, as well as for its extension with two dynamical metrics. These results may indicate that static black holes in massive gravity do not exist. For the graviton mass of the order of the Hubble scale, however, the instability timescale is of order of the Hubble time.

Effects of osteopathic manipulative treatment of the pivots on lower limb function in young professional football players

2022

Introduction: The most frequent injuries in professional soccer players are those pertinent to the lower limbs. In particular, strains of the hamstrings and ligamentous injuries of the knee. Therefore, preventive measures are aimed to reduce such events. We aimed to investigate if an osteopathic manipulative treatment (OMT) of the pivots could improve lower limb function in young professional football players. Methods: Thirty-eight young male professional football players were recruited (mean age 17.8 +/- 0.44 years). These were randomly assigned to an OMT or control group (n 1/4 20 and 18, respectively). Both groups underwent osteopathic evaluation. A sit-and-reach test, a vertical jump te…

Gravity-mediated dark matter in clockwork/linear dilaton extra-dimensions

2020

We study for the first time the possibility that Dark Matter (represented by particles with spin $0,1/2$ or $1$) interacts gravitationally with Standard Model particles in an extra-dimensional Clockwork/Linear Dilaton model. We assume that both, the Dark Matter and the Standard Model, are localized in the IR-brane and only interact via gravitational mediators, namely the Kaluza-Klein (KK) graviton and the radion/KK-dilaton modes. We analyse in detail the Dark Matter annihilation channel into Standard Model particles and into two on-shell Kaluza-Klein towers (either two KK-gravitons, or two radion/KK-dilatons, or one of each), finding that it is possible to obtain the observed relic abundanc…

Searching for Jumbled Patterns in Strings

2009

On Approximate Jumbled Pattern Matching in Strings

2011

Given a string s, the Parikh vector of s, denoted p(s), counts the multiplicity of each character in s. Searching for a match of a Parikh vector q in the text s requires finding a substring t of s with p(t) = q. This can be viewed as the task of finding a jumbled (permuted) version of a query pattern, hence the term Jumbled Pattern Matching. We present several algorithms for the approximate version of the problem: Given a string s and two Parikh vectors u, v (the query bounds), find all maximal occurrences in s of some Parikh vector q such that u <= q <= v. This definition encompasses several natural versions of approximate Parikh vector search. We present an algorithm solving this problem …

Light majoron cold dark matter from topological defects and the formation of boson stars

2019

We show that for a relatively light majoron ($\ll 100 $ eV) non-thermal production from topological defects is an efficient production mechanism. Taking the type I seesaw as benchmark scheme, we estimate the primordial majoron abundance and determine the required parameter choices where it can account for the observed cosmological dark matter. The latter is consistent with the scale of unification. Possible direct detection of light majorons with future experiments such as PTOLEMY and the formation of boson stars from the majoron dark matter are also discussed.

A loop-free two-close Gray-code algorithm for listing k-ary Dyck words

2006

AbstractP. Chase and F. Ruskey each published a Gray code for length n binary strings with m occurrences of 1, coding m-combinations of n objects, which is two-close—that is, in passing from one binary string to its successor a single 1 exchanges positions with a 0 which is either adjacent to the 1 or separated from it by a single 0. If we impose the restriction that any suffix of a string contains at least k−1 times as many 0's as 1's, we obtain k-suffixes: suffixes of k-ary Dyck words. Combinations are retrieved as special case by setting k=1 and k-ary Dyck words are retrieved as a special case by imposing the additional condition that the entire string has exactly k−1 times as many 0's a…