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839
result(s) for
"Currie, James"
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NNLO QCD corrections to jet production in deep inelastic scattering
A
bstract
Hadronic jets in deeply inelastic electron-proton collisions are produced by the scattering of a parton from the proton with the virtual gauge boson mediating the interaction. The HERA experiments have performed precision measurements of inclusive single jet production and di-jet production in the Breit frame, which provide important constraints on the strong coupling constant and on parton distributions in the proton. We describe the calculation of the next-to-next-to-leading order (NNLO) QCD corrections to these processes, and assess their size and impact. A detailed comparison with data from the H1 and ZEUS experiments highlights that inclusive single jet production displays a better perturbative convergence than di-jet production. We also observe that the event selection cuts in some of the di-jet measurements of both H1 and ZEUS induce an infrared sensitivity that destabilises the perturbative stability of the predictions. Our results open up new opportunities for QCD precision studies with jet production observables in deep inelastic scattering.
Journal Article
Henry's crime
Released from prison for a crime he didn't commit, an ex-con targets the same bank he was sent away for robbing.
DVD
Infrared structure at NNLO using antenna subtraction
A
bstract
We consider the infrared structure of hadron-hadron collisions at next-to-next-to leading order using the antenna subtraction method. The general form of the subtraction terms is presented for double real, real-virtual and double virtual contributions. At NLO and NNLO it is shown that the virtual and double virtual subtraction terms can be written in terms of
integrated dipoles
, formed by systematically combining the mass factorisation contributions and integrated antenna functions. The integrated dipoles describing
ℓ
unresolved partons, denoted
, are related to Catani’s IR singularity operators,
. It is shown that the IR pole structure of the virtual and double virtual contributions can be written as a sum over integrated dipoles within the antenna subtraction formalism and the master expressions analogous to Catani’s one- and two-loop factorisation formulae are derived. To demonstrate the techniques described in this paper, we apply antenna subtraction to the production of two gluon jets via quark-antiquark scattering at NLO and NNLO. Double real, real-virtual and double virtual subtraction terms are explicitly derived for the leading colour NNLO contribution.
Journal Article
Infrared sensitivity of single jet inclusive production at hadron colliders
A
bstract
Jet production at hadron colliders is a benchmark process to probe the dynamics of the strong interaction and the structure of the colliding hadrons. One of the most basic jet production observables is the single jet inclusive cross section, which is obtained by summing all jets that are observed in an event. Our recent computation of next-to-next-to-leading order (NNLO) QCD contributions to single jet inclusive observables uncovered large corrections in certain kinematical regions, which also resulted in a sizeable ambiguity on the appropriate choice of renormalization and factorization scales. We now perform a detailed investigation of the infrared sensitivity of the different ingredients to the single jet inclusive cross section. We show that the contribution from the second jet, ordered in transverse momentum
p
T
, in the event is particularly sensitive to higher order effects due to implicit restrictions on its kinematics. By investigating the second-jet transverse momentum distribution, we identify large-scale cancellations between different kinematical event configurations, which are aggravated by certain types of scale choice. Taking perturbative convergence and stability as selection criteria enables us to single out the total partonic transverse energy
Ĥ
T
and twice the individual jet transverse momentum 2
p
T
(with which
Ĥ
T
coincides in Born kinematics) as the most appropriate scales in the perturbative description of single jet inclusive production.
Journal Article
Erratum to: NNLO QCD corrections to jet production in deep inelastic scattering
We correct an error in the implementation of specific integrated initial-final antenna functions that impact the numerical predictions for the DIS process.
Journal Article
The repetition threshold for binary rich words
A word of length$n$is rich if it contains$n$nonempty palindromic factors. An infinite word is rich if all of its finite factors are rich. Baranwal and Shallit produced an infinite binary rich word with critical exponent$2+\\sqrt{2}/2$( $\\approx 2.707$ ) and conjectured that this was the least possible critical exponent for infinite binary rich words (i.e., that the repetition threshold for binary rich words is$2+\\sqrt{2}/2$ ). In this article, we give a structure theorem for infinite binary rich words that avoid$14/5$ -powers (i.e., repetitions with exponent at least 2.8). As a consequence, we deduce that the repetition threshold for binary rich words is$2+\\sqrt{2}/2$ , as conjectured by Baranwal and Shallit. This resolves an open problem of Vesti for the binary alphabet; the problem remains open for larger alphabets. Comment: 16 pages
Journal Article
Electroconvulsive therapy reduces frontal cortical connectivity in severe depressive disorder
To date, electroconvulsive therapy (ECT) is the most potent treatment in severe depression. Although ECT has been successfully applied in clinical practice for over 70 years, the underlying mechanisms of action remain unclear. We used functional MRI and a unique data-driven analysis approach to examine functional connectivity in the brain before and after ECT treatment. Our results show that ECT has lasting effects on the functional architecture of the brain. A comparison of pre- and posttreatment functional connectivity data in a group of nine patients revealed a significant cluster of voxels in and around the left dorsolateral prefrontal cortical region (Brodmann areas 44, 45, and 46), where the average global functional connectivity was considerably decreased after ECT treatment (P < 0.05, family-wise error-corrected). This decrease in functional connectivity was accompanied by a significant improvement (P < 0.001) in depressive symptoms; the patients’ mean scores on the Montgomery Asberg Depression Rating Scale pre- and posttreatment were 36.4 (SD = 4.9) and 10.7 (SD = 9.6), respectively. The findings reported here add weight to the emerging \"hyperconnectivity hypothesis\" in depression and support the proposal that increased connectivity may constitute both a biomarker for mood disorder and a potential therapeutic target.
Journal Article
The Congressional Public Health Caucus
The more than 200 caucuses in the US House of Representatives are what might he described as \"affinity groups,\" composed of members of the House who identify with a particular cause or who share a passion for something, whether it is prevention or cure of a disease, country region of the world, idea, or something else entirely. Their scope is as varied, as are the interests of the members, ranging from diseases and medical conditions (Alzheimer's Caucus, Diabetes Caucus, Fetal Alcohol Caucus), to countries (Norway Caucus, French Caucus, Armenian Caucus), to region (Gulf of Mexico Caucus, Northwest Border Caucus, Chesapeake Bay Caucus), to outdoor recreation (Biking Caucus, Sportsmen's Caucus, Recreational Boating Caucus), to cause (Out of Iraq Caucus, Recycling Caucus, Reading Caucus), to just plain interesting (Bourbon Caucus, Horse Caucus, Zoo and Aquarium Caucus). What was lacking until 2015 was a Congressional Public Health Caucus. Here, Currie details the idea congressional public health caucus.
Journal Article
Antisquares and Critical Exponents
The (bitwise) complement$\\overline{x}$of a binary word$x$is obtained by changing each$0$in$x$to$1$and vice versa. An$\\textit{antisquare}$is a nonempty word of the form$x\\, \\overline{x}$ . In this paper, we study infinite binary words that do not contain arbitrarily large antisquares. For example, we show that the repetition threshold for the language of infinite binary words containing exactly two distinct antisquares is$(5+\\sqrt{5})/2$ . We also study repetition thresholds for related classes, where \"two\" in the previous sentence is replaced by a larger number. We say a binary word is$\\textit{good}$if the only antisquares it contains are$01$and$10$ . We characterize the minimal antisquares, that is, those words that are antisquares but all proper factors are good. We determine the growth rate of the number of good words of length$n$and determine the repetition threshold between polynomial and exponential growth for the number of good words.
Journal Article