scholarly journals The role of the threshold variable in soft-gluon resummation of the $$ t\overline{t}h $$ production process

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Melissa van Beekveld ◽  
Wim Beenakker
Keyword(s):  
Cross Section ◽  
Top Quark ◽  
Mellin Transform ◽  
Invariant Mass Distribution ◽  
Hadron Collider ◽  
Soft Gluon ◽  
Deformation Method ◽  
Final State ◽  
Scale Uncertainty

Abstract We study the role of the scale of the threshold variable in soft-gluon threshold resummation. We focus on the computation of the resummed total cross section, the final-state invariant-mass distribution, and transverse-momentum distribution of the Higgs boson when produced in association with a top-anti-top quark pair for the Large Hadron Collider operating at 13 TeV. We show that different choices for the scale of the threshold variable result in differences at next-to-leading power, i.e. contributions that are down by one power of the threshold variable. These contributions are noticeable numerically, although their effect on the resummed observables lies within the scale uncertainty of those observables. The average central results, obtained after combining several central- scale choices, agree remarkably well for different choices of the threshold variable. However, different threshold choices do affect the resulting scale uncertainty. To compute our results, we introduce a novel numerical method that we call the deformation method, which aids the stabilization of the inverse Mellin transform in cases where the analytical Mellin transform of the partonic cross section is unknown. We show that this method leads to a factor of 10 less function evaluations, while gaining a factor of 4 − 5 in numerical precision when compared to the standard method.

scholarly journals KK Higgs produced in association with a top quark pair in the bulk RS model

2019 ◽  
Vol 79 (11) ◽  
Author(s):  
N. Manglani ◽  
A. Misra ◽  
K. Sridhar
Keyword(s):  
Higgs Boson ◽  
Large Hadron Collider ◽  
Cross Section ◽  
Top Quark ◽  
Production Cross Section ◽  
Search Strategy ◽  
Production Cross ◽  
Hadron Collider ◽  
Final State ◽  
Kaluza Klein

AbstractWe present a search strategy for the first Kaluza–Klein (KK) mode of the Higgs boson in the framework of the Randall–Sundrum (RS) model with a deformed metric. We study the production of this massive excitation in association with a $$ t {\bar{t}}$$tt¯ pair at the large hadron collider (LHC). The KK Higgs primarily decays into a boosted $$t {\bar{t}}$$tt¯ final state and we then end up with an interesting four-top final state of which two are boosted. The boosted products in the final state improve the sensitivity for the search of the KK Higgs in this channel whose production cross-section is otherwise rather small. Our results suggest that masses of the KK Higgs resonance upto about 1.2 TeV may be explorable at the highest planned luminosities of the LHC. Beyond this mass, the KK Higgs cross-section is too tiny for it to be explored at the LHC and may be possible only at a future higher energy collider.

scholarly journals Search for pair production of third-generation scalar leptoquarks decaying into a top quark and a τ-lepton in pp collisions at $$ \sqrt{s} $$ = 13 TeV with the ATLAS detector

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
◽  
G. Aad ◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
...  
Keyword(s):  
Pair Production ◽  
Top Quark ◽  
Production Cross ◽  
Branching Fraction ◽  
Hadron Collider ◽  
Atlas Detector ◽  
Third Generation ◽  
Final State ◽  
Generation Scalar ◽  
Scalar Leptoquarks

Abstract A search for pair production of third-generation scalar leptoquarks decaying into a top quark and a τ-lepton is presented. The search is based on a dataset of pp collisions at $$ \sqrt{s} $$ s = 13 TeV recorded with the ATLAS detector during Run 2 of the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb−1. Events are selected if they have one light lepton (electron or muon) and at least one hadronically decaying τ -lepton, or at least two light leptons. In addition, two or more jets, at least one of which must be identified as containing b-hadrons, are required. Six final states, defined by the multiplicity and flavour of lepton candidates, are considered in the analysis. Each of them is split into multiple event categories to simultaneously search for the signal and constrain several leading backgrounds. The signal-rich event categories require at least one hadronically decaying τ-lepton candidate and exploit the presence of energetic final-state objects, which is characteristic of signal events. No significant excess above the Standard Model expectation is observed in any of the considered event categories, and 95% CL upper limits are set on the production cross section as a function of the leptoquark mass, for different assumptions about the branching fractions into tτ and bν. Scalar leptoquarks decaying exclusively into tτ are excluded up to masses of 1.43 TeV while, for a branching fraction of 50% into tτ, the lower mass limit is 1.22 TeV.

scholarly journals Forward dijets in proton-nucleus collisions at next-to-leading order: the real corrections

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Edmond Iancu ◽  
Yair Mulian
Keyword(s):  
Cross Section ◽  
Soft Gluon ◽  
Effective Theory ◽  
Dglap Evolution ◽  
Leading Order ◽  
Final State ◽  
Dijet Production ◽  
The Real ◽  
First Case ◽  
Subsequent Publication

Abstract Using the CGC effective theory together with the hybrid factorisation, we study forward dijet production in proton-nucleus collisions beyond leading order. In this paper, we compute the “real” next-to-leading order (NLO) corrections, i.e. the radiative corrections associated with a three-parton final state, out of which only two are being measured. To that aim, we start by revisiting our previous results for the three-parton cross-section presented in [1]. After some reshuffling of terms, we deduce new expressions for these results, which not only look considerably simpler, but are also physically more transparent. We also correct several errors in this process. The real NLO corrections to inclusive dijet production are then obtained by integrating out the kinematics of any of the three final partons. We explicitly work out the interesting limits where the unmeasured parton is either a soft gluon, or the product of a collinear splitting. We find the expected results in both limits: the B-JIMWLK evolution of the leading-order dijet cross-section in the first case (soft gluon) and, respectively, the DGLAP evolution of the initial and final states in the second case (collinear splitting). The “virtual” NLO corrections to dijet production will be presented in a subsequent publication.

scholarly journals EXTRACTION OF RESONANCE PARAMETERS AND ROLE OF THE FINAL STATE INTERACTIONS

2014 ◽  
Vol 26 ◽  
pp. 1460082 ◽  
Author(s):  
IGOR I. STRAKOVSKY ◽  
WILLIAM J. BRISCOE ◽  
ALEXANDER E. KUDRYAVTSEV ◽  
VLADIMIR E. TARASOV
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Impulse Approximation ◽  
Pion Photoproduction ◽  
Final State ◽  
The World ◽  
Final State Interactions ◽  
Watson’S Theorem ◽  
Photoproduction Data

We present an overview of the SAID group effort to analyze new γn → π-p cross sections vs. the world database to get new multipoles and determine neutron electromagnetic couplings. The differential cross section for the processes γn → π-p was extracted from new measurements at CLAS and MAMI-B accounting for Fermi motion effects in the impulse approximation (IA) as well as NN- and πN-FSI effects beyond the IA. We evaluated results of several pion photoproduction analyses and compared πN PWA results as a constraint for analyses of pion photoproduction data (Watson's theorem).

scholarly journals ASSOCIATED PRODUCTION OF THE CHARGED HIGGS BOSON AND SINGLE TOP QUARK AT THE LHC

2009 ◽  
Vol 24 (02) ◽  
pp. 143-150 ◽  
Author(s):  
YAO-BEI LIU ◽  
JIE-FEN SHEN
Keyword(s):  
Higgs Boson ◽  
Cross Section ◽  
Top Quark ◽  
Production Cross ◽  
Hadron Collider ◽  
Charged Higgs Boson ◽  
Cern Large Hadron Collider ◽  
Associated Production ◽  
Single Top ◽  
Charged Higgs

The left–right twin Higgs (LRTH) model predicts the existence of the charged Higgs ϕ±. In this paper, we study the production of the charged Higgs boson ϕ- with single top quark via the process bg → tϕ- at the CERN Large Hadron Collider (LHC). The numerical results show that the production cross-section can reach the level of 10 pb in the reasonable parameter space of the LRTH model. We expect that, as long as it is not too heavy, the possible signatures of the heavy charged Higgs boson ϕ-> might be detected via the decay mode [Formula: see text] at the LHC experiments.

CDF RESULTS ON TOP

1996 ◽  
Vol 11 (12) ◽  
pp. 2045-2064
Author(s):  
ANDREW BERETVAS
Keyword(s):  
Cross Section ◽  
Top Quark ◽  
Quark Mass ◽  
Production Cross ◽  
Secondary Vertex ◽  
Top Quark Mass ◽  
Final State ◽  
Vertex Detector ◽  
Text Production ◽  
Integrated Luminosity

CDF has established the existence of the top quark. Results from [Formula: see text] collisions at [Formula: see text] TeV are presented. In the dilepton final state we find seven events with a background of 1.3±0.3. In the e, μ+v+jets channel with a b identified via a secondary vertex detector (SVX), we find 21 events with a background of 5.5±1.8. We measure the top quark mass to be 176±8 (stat) ±10 (syst) GeV/c2, and the [Formula: see text] production cross section to be [Formula: see text] . The integrated luminosity for the results presented in this paper is 67 pb−1. The CDF detector needs to be upgraded for our next run. The integrated luminosity for the next run is expected to be more than 1000 pb −1.

PROBING THE STANDARD MODEL WITH DILEPTON DECAYS OF TOP QUARK PAIRS AT CDF

2007 ◽  
Vol 22 (38) ◽  
pp. 2873-2884
Author(s):  
DANIEL WHITESON
Keyword(s):  
Standard Model ◽  
Cross Section ◽  
Top Quark ◽  
Production Cross Section ◽  
Production Cross ◽  
Fundamental Theory ◽  
Final State ◽  
Quark Pairs ◽  
The Standard Model ◽  
Selection Of

The dilepton decays of the top quark are a powerful laboratory for probing the Standard Model and searching for hints of a more fundamental theory. We present a detailed analysis of the production cross section and the kinematic qualities of top quark pair candidate events in [Formula: see text] collisions at [Formula: see text] = 1.96 TeV collected by the CDF detector which include two leptons in the final state, suggesting the decay [Formula: see text]. We describe the selection of candidate events to suppress major backgrounds and present the number of observed events over background. As a test of the top quark hypothesis, the kinematics of the events are analyzed via a measurement of M top with unprecedented precision.

scholarly journals Measurements of top-quark pair differential and double-differential cross-sections in the $$\ell $$+jets channel with pp collisions at $$\sqrt{s}=13$$ TeV using the ATLAS detector

2019 ◽  
Vol 79 (12) ◽  
Author(s):  
G. Aad ◽  
◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
...  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Differential Cross ◽  
Top Quark ◽  
Hadron Collider ◽  
Atlas Detector ◽  
Double Differential Cross Section ◽  
Quark Pairs ◽  
Top Quark Production ◽  
Using Data

AbstractSingle- and double-differential cross-section measurements are presented for the production of top-quark pairs, in the lepton + jets channel at particle and parton level. Two topologies, resolved and boosted, are considered and the results are presented as a function of several kinematic variables characterising the top and $$t\bar{t}$$ t t ¯ system and jet multiplicities. The study was performed using data from pp collisions at centre-of-mass energy of 13 TeV collected in 2015 and 2016 by the ATLAS detector at the CERN Large Hadron Collider (LHC), corresponding to an integrated luminosity of $$36~\mathrm {fb}^{-1}$$ 36 fb - 1 . Due to the large $$t\bar{t}$$ t t ¯ cross-section at the LHC, such measurements allow a detailed study of the properties of top-quark production and decay, enabling precision tests of several Monte Carlo generators and fixed-order Standard Model predictions. Overall, there is good agreement between the theoretical predictions and the data.

scholarly journals Measurement of fiducial and differential $$W^+W^-$$ production cross-sections at $$\sqrt{s}=13$$ TeV with the ATLAS detector

2019 ◽  
Vol 79 (10) ◽  
Author(s):  
M. Aaboud ◽  
◽  
G. Aad ◽  
B. Abbott ◽  
D. C. Abbott ◽  
...  
Keyword(s):  
Transverse Momentum ◽  
Cross Section ◽  
Cross Sections ◽  
Top Quark ◽  
Production Cross ◽  
Hadron Collider ◽  
Effective Field ◽  
Electroweak Gauge Boson ◽  
Using Data ◽  
Background Events

Abstract A measurement of fiducial and differential cross-sections for $$W^+W^-$$W+W- production in proton–proton collisions at $$\sqrt{s}=13$$s=13 TeV with the ATLAS experiment at the Large Hadron Collider using data corresponding to an integrated luminosity of 36.1 $$\hbox {fb}^{-1}$$fb-1 is presented. Events with one electron and one muon are selected, corresponding to the decay of the diboson system as $$WW\rightarrow e^{\pm }\nu \mu ^{\mp }\nu $$WW→e±νμ∓ν. To suppress top-quark background, events containing jets with a transverse momentum exceeding 35 GeV are not included in the measurement phase space. The fiducial cross-section, six differential distributions and the cross-section as a function of the jet-veto transverse momentum threshold are measured and compared with several theoretical predictions. Constraints on anomalous electroweak gauge boson self-interactions are also presented in the framework of a dimension-six effective field theory.

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