Kaluza–Klein gluon + jets associated production at the Large Hadron Collider

AbstractThe Kaluza–Klein excitations of gluons offer the exciting possibility of probing bulk Randall–Sundrum (RS) models. In these bulk models either a custodial symmetry or a deformation of the metric away from AdS is invoked in order to deal with electroweak precision tests. Addressing both these models, we suggest a new channel in which to study the production of KK-gluons (gKK): one where it is produced in association with one or more hard jets. The cross-section for the gKK + jets channel is significant because of several contributing sub-processes. In particular, the 1-jet and the 2-jet associated processes are important because at these orders in QCD the qg and the gg initial states respectively come into play. We have performed a hadron-level simulation of the signal and present strategies to effectively extract the signal from what could potentially be a huge background. We present results for the kinematic reach of the LHC Run-II for different gKK masses in bulk-RS models

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

We 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 $$t {\bar{t}}$$ pair at the large hadron collider (LHC). The KK Higgs primarily decays into a boosted $$t {\bar{t}}$$ 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

The bulk Higgs in the deformed RS model

Electroweak precision tests allow for lighter Kaluza–Klein (KK) Higgs modes in the deformed Randall–Sundrum (RS) model than in models with custodial symmetry. The first KK mode of the Higgs (h1) in such a model could have a mass as low as 900 GeV. In this paper, we study the production of h1 and its subsequent decay to a tt¯ pair at the Large Hadron Collider (LHC), in the context of the deformed RS model. We have performed a hadron-level Monte Carlo simulation of the signal and the relevant Standard Model background. We present strategies to effectively suppress the huge SM background and provide a signal that is tractable at the future runs of the LHC. Keywords: Warped 5D model, Hierarchy problem, Deformed metric, Higg

A Higgs in the Warped Bulk and LHC signals

International audienceWarped models with the Higgs in the bulk can generate light Kaluza-Klein (KK) Higgs modes consistent with the electroweak precision analysis. The first KK mode of the Higgs (h$_{1}$) could lie in the 1-2 TeV range in the models with a bulk custodial symmetry. We find that the h$_{1}$ is gaugephobic and decays dominantly into a $t\overline{t}$ pair. We also discuss the search strategy for h$_{1}$ decaying to $t\overline{t}$ at the Large Hadron Collider. We used substructure tools to suppress the large QCD background associated with this channel. We find that h$_{1}$ can be probed at the LHC run-2 with an integrated luminosity of 300 fb$^{−1}$

Searches for Boosted Top Quarks at the LHC

International audienceMany beyond the Standard Model theories predict massive new particles. The detection of such massive particles at the Large Hadron Collider (LHC) is very challenging. The heavy mass of these particles ensures their decay to boosted top quarks. Thus, the search for boosted top quarks allows the detection for these particles. We have studied the phenomenology of massive first Kaluza Klein mode for the Higgs boson and the gluon decaying to top quarks in two classes of bulk Randall–Sundrum model. We show that such resonances are within the present reach of the LHC

Testing charge-radius coupling of the composite Higgs boson at hadron colliders

We explore the collider relevance of a charge-radius coupling of the composite Higgs boson. This coupling offers a deep probe of the composite nature of the Higgs mechanism, being sensitive to the electromagnetic and weak isospin structure of its constituents. The main collider effect consists in the production of the Higgs boson in association with a light composite pseudo-scalar. We present an exploratory cut-and-count analysis at hadron colliders, like the LHC, showing that an efficient background suppression can be achieved. More sophisticated techniques, however, are necessary to select a sufficient number of signal events, due to the small production rates. This justifies further investigation of this channel, which is highly complementary to other searches for compositeness in the Higgs sector

Bacterial Bronchitis Caused by Streptococcus pneumoniae and Nontypable Haemophilus influenzae in Children The Impact of Vaccination

Background: Protracted bacterial bronchitis is a major cause of persistent cough in childhood. The organisms most commonly isolated are nontypable Haemophilus infiuenzae and Streptococcus pneumoniae. There are no studies addressing typing of these organisms when recovered from the lower airways. Methods: Isolates of these two organisms (identified in BAL samples from children undergoing routine investigation of a chronic cough thought to be attributable to a protracted bacterial bronchitis) were subject to typing. Samples were collected in Sheffield, England, and Athens, Greece. The majority of the children from Sheffield had received pneumococcal-conjugate vaccines 7 or 13 (PCV-7 or PCV-13) conjugate vaccine but only a minority of Greek children had received PCV-7. Results: All 18 S pneumoniae isolates from Greek BAL samples are serotypes contained in PCV-13 while 10 are contained in PCV-7. In contrast, 28 of the 39 samples from Sheffield contained serotypes that are not included in PCV-13. All 26 of the nontypable H influenzae samples obtained in Sheffield produced distinct multilocus variable-number tandem repeat analysis profiles. There was a significant difference between children from Athens and Sheffield in the distribution of serotypes contained or not contained in the pneumococcal vaccine (P = .04). More specifically, immunization with pneumococcal vaccine was related with isolation of S pneumoniae serotypes not included in the vaccine (OR, 0.021; CI, 0.003-0.115; P < .001). Conclusions: The data suggest that both vaccine and nonvaccine S pneumoniae serotypes may play a role in protracted bacterial bronchitis and provide some hints that serotype replacement may occur in response to the introduction of conjugate vaccines. CHEST 2013; 143(1):152-15

Bacterial Bronchitis Caused by Streptococcus pneumoniae and Nontypable Haemophilus influenzae in Children The Impact of Vaccination

Background: Protracted bacterial bronchitis is a major cause of persistent cough in childhood. The organisms most commonly isolated are nontypable Haemophilus infiuenzae and Streptococcus pneumoniae. There are no studies addressing typing of these organisms when recovered from the lower airways. Methods: Isolates of these two organisms (identified in BAL samples from children undergoing routine investigation of a chronic cough thought to be attributable to a protracted bacterial bronchitis) were subject to typing. Samples were collected in Sheffield, England, and Athens, Greece. The majority of the children from Sheffield had received pneumococcal-conjugate vaccines 7 or 13 (PCV-7 or PCV-13) conjugate vaccine but only a minority of Greek children had received PCV-7. Results: All 18 S pneumoniae isolates from Greek BAL samples are serotypes contained in PCV-13 while 10 are contained in PCV-7. In contrast, 28 of the 39 samples from Sheffield contained serotypes that are not included in PCV-13. All 26 of the nontypable H influenzae samples obtained in Sheffield produced distinct multilocus variable-number tandem repeat analysis profiles. There was a significant difference between children from Athens and Sheffield in the distribution of serotypes contained or not contained in the pneumococcal vaccine (P = .04). More specifically, immunization with pneumococcal vaccine was related with isolation of S pneumoniae serotypes not included in the vaccine (OR, 0.021; CI, 0.003-0.115; P &lt; .001). Conclusions: The data suggest that both vaccine and nonvaccine S pneumoniae serotypes may play a role in protracted bacterial bronchitis and provide some hints that serotype replacement may occur in response to the introduction of conjugate vaccines. CHEST 2013; 143(1):152-15