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Search for the flavor-changing neutral current interactions of the top quark and the Higgs boson which decays into a pair of b quarks at $\sqrt{s}=$ 13 TeV

A search for flavor-changing neutral currents (FCNC) in events with the top quark and the Higgs boson is presented. The Higgs boson decay to a pair of b quarks is considered. The data sample corresponds to an integrated luminosity of 35.9 fb $^{−1}$ recorded by the CMS experiment at the LHC in proton-proton collisions at $\sqrt{s}=13$ TeV. Two channels are considered: single top quark FCNC production in association with the Higgs boson (pp → tH), and top quark pair production with FCNC decay of the top quark (t → qH). Final states with one isolated lepton and at least three reconstructed jets, among which at least two are associated with b quarks, are studied. No significant deviation is observed from the predicted background. Observed (expected) upper limits at 95% confidence level are set on the branching fractions of top quark decays, ℬ(t → uH)

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Muhammad Ahmad, Benjamin William Allen, Georgios Anagnostou, Konstantin Androsov, Tagir Aushev, Michele Bianco, Roberto Castello, Xin Chen, Yixing Chen, Tian Cheng, Davide Cieri, Giuseppe Codispoti, Pratyush Das, Alessandro Degano, Milos Dordevic, Dipanwita Dutta, Matthias Finger, Francesco Fiori, Daniel Gonzalez, Seungkyu Ha, Csaba Hajdu, Peter Hansen, Ali Harb, Miao Hu, Alexis Kalogeropoulos, Viktor Khristenko, Donghyun Kim, Ji Hyun Kim, Sanjeev Kumar, Vineet Kumar, Ajay Kumar, Ekaterina Kuznetsova, Ho Ling Li, Jing Li, Wei Li, Shuai Liu, Zhen Liu, Hao Liu, Werner Lustermann, Bibhuprasad Mahakud, Maren Tabea Meinhard, Thomas Muller, Ioannis Papadopoulos, Vladimir Petrov, Quentin Python, Andrea Rizzi, Paolo Ronchese, Varun Sharma, Ashish Sharma, Lesya Shchutska, Wei Shi, Kun Shi, Muhammad Shoaib, Gurpreet Singh, Jan Steggemann, Marco Trovato, Andromachi Tsirou, David Vannerom, Joao Varela, Mingkui Wang, Jian Wang, Hui Wang, Qian Wang, Zheng Wang, Yi Wang, Siyuan Wang, Muhammad Waqas, Matthias Weber, Matthias Wolf, Wenjing Wu, Fan Xia, Meng Xiao, Zhirui Xu, Yong Yang, Kai Yi
2017
Article

Résumé

Official source

https://infoscience.epfl.ch/record/274831?ln=fr

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Concepts associés (20)

Concepts associés

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Publications associées (101)

Publications associées

Chargement

Luminosité

En astronomie, la luminosité est la quantité totale d'énergie émise par unité de temps (le flux énergétique), par une étoile, une galaxie, ou n'importe quel autre objet céleste. Elle s'exprime en pr

Intervalle de confiance

vignette|Chaque ligne montre 20 échantillons tirés selon la loi normale de moyenne μ. On y montre l'intervalle de confiance de niveau 50% pour la moyenne correspondante aux 20 échantillons, marquée pa

Boson de Higgs

thumb|De gauche à droite : Kibble, Guralnik, Hagen, Englert et Brout, en 2010. Le boson de Higgs ou boson BEH, est une particule élémentaire dont l'existence, postulée indépendamment en juin 1964 par

Search for a charged Higgs boson decaying to charm and bottom quarks in proton-proton collisions at $ \sqrt{s}=8 $ TeV

Muhammad Ahmad, Benjamin William Allen, Georgios Anagnostou, Konstantin Androsov, Tagir Aushev, Michele Bianco, Yixing Chen, Xin Chen, Tian Cheng, Davide Cieri, Giuseppe Codispoti, Pratyush Das, Abhisek Datta, Milos Dordevic, Dipanwita Dutta, Matthias Finger, Daniel Gonzalez, Ruchi Gupta, Seungkyu Ha, Csaba Hajdu, Peter Hansen, Ali Harb, Miao Hu, Alexis Kalogeropoulos, Viktor Khristenko, Donghyun Kim, Ji Hyun Kim, Vineet Kumar, Ajay Kumar, Sanjeev Kumar, Ekaterina Kuznetsova, Yiming Li, Wei Li, Ho Ling Li, Jing Li, Lei Li, Zhen Liu, Hao Liu, Werner Lustermann, Bibhuprasad Mahakud, Maren Tabea Meinhard, Amr Mohamed, Thomas Muller, Ioannis Papadopoulos, Vladimir Petrov, Quentin Python, Andrea Rizzi, Paolo Ronchese, Sourav Sen, Varun Sharma, Ashish Sharma, Lesya Shchutska, Wei Shi, Kun Shi, Muhammad Shoaib, Gurpreet Singh, Jan Steggemann, Marco Trovato, Andromachi Tsirou, David Vannerom, Joao Varela, Zheng Wang, Mingkui Wang, Jian Wang, Xiao Wang, Hui Wang, Qian Wang, Siyuan Wang, Yi Wang, Muhammad Waqas, Matthias Weber, Matthias Wolf, Fan Xia, Meng Xiao, Zhirui Xu, Yong Yang

A search for charged Higgs boson decaying to a charm and a bottom quark (

{\mathrm{H}}^{+}\to \mathrm{c}\overline{\mathrm{b}}

) is performed using 19.7 fb

^{−1}

of pp collision data at

\sqrt{s}=8

TeV. The production mechanism investigated in this search is

\mathrm{t}\overline{\mathrm{t}}

pair production in which one top quark decays to a charged Higgs boson and a bottom quark and the other decays to a charged lepton, a neutrino, and a bottom quark. Charged Higgs boson decays to

\mathrm{c}\overline{\mathrm{b}}

are searched for, resulting in a final state containing at least four jets, a charged lepton (muon or electron), and missing transverse momentum. A kinematic fit is performed to identify the pair of jets least likely to be the bottom quarks originating from direct top quark decays and the invariant mass of this pair is used as the final observable in the search. No evidence for the presence of a charged Higgs boson is observed and upper limits at 95% confidence level of 0.8–0.5% are set on the branching fraction ℬ(t → H

^{+}

b), assuming ℬ(H

^{+}

→

\mathrm{c}\overline{\mathrm{b}}

) = 1.0 and ℬ(t → H

^{+}

b) + ℬ(t → Wb) = 1.0, for the charged Higgs boson mass range 90–150 GeV.

2018

Chargement

Search for vector-like T quarks decaying to top quarks and Higgs bosons in the all-hadronic channel using jet substructure

Muhammad Ahmad, Georgios Anagnostou, Konstantin Androsov, Alexandre Aubin, Roberto Castello, Yixing Chen, Tian Cheng, Giuseppe Codispoti, Alessandro Degano, Charles Dietz, Milos Dordevic, Dipanwita Dutta, Matthias Finger, Francesco Fiori, Ruchi Gupta, Csaba Hajdu, Alexis Kalogeropoulos, Donghyun Kim, Ji Hyun Kim, Vineet Kumar, Ajay Kumar, Sanjeev Kumar, Ekaterina Kuznetsova, Ho Ling Li, Wei Li, Hao Liu, Shuai Liu, Werner Lustermann, Matteo Marone, Thomas Muller, Ioannis Papadopoulos, Vladimir Petrov, Quentin Python, Andrea Rizzi, Paolo Ronchese, Sourav Sen, Ashish Sharma, Varun Sharma, Lesya Shchutska, Muhammad Shoaib, Michal Simon, Gurpreet Singh, Jan Steggemann, Wei Sun, Andromachi Tsirou, Paul Turner, Joao Varela, Jian Wang, Rui Wang, Qian Wang, Zheng Wang, Matthias Weber, Matthias Wolf, Meng Xiao, Zhirui Xu, Yong Yang, Fan Yang, Kai Yi, Lei Zhang

A search is performed for a vector-like heavy T quark that is produced in pairs and that decays to a top quark and a Higgs boson. The data analysed correspond to an integrated luminosity of 19.7 fb

^{−1}

collected with the CMS detector in proton-proton collisions at

\sqrt{s}=8

TeV. For T quarks with large mass values the top quarks and Higgs bosons can have significant Lorentz boosts, so that their individual decay products often overlap and merge. Methods are applied to resolve the substructure of such merged jets. Upper limits on the production cross section of a T quark with mass between 500 and 1000 GeV/c

^{2}

are derived. If the T quark decays exclusively to tH, the observed (expected) lower limit on the mass of the T quark is 745 (773) GeV/c

^{2}

at 95% confidence level. For the first time an algorithm is used for tagging boosted Higgs bosons that is based on a combination of jet substructure information and b tagging.

2015

Chargement

Search for anomalous production of events with three or more leptons in $pp$ collisions at $\sqrt(s) =$ 8 TeV

Muhammad Ahmad, Georgios Anagnostou, Konstantin Androsov, Giovanni Bianchi, Roberto Castello, Yixing Chen, Jie Chen, Tian Cheng, Giuseppe Codispoti, Alessandro Degano, Charles Dietz, Milos Dordevic, Dipanwita Dutta, Matthias Finger, Francesco Fiori, Yu Fu, Yifei Guo, Ruchi Gupta, Csaba Hajdu, Alexis Kalogeropoulos, Donghyun Kim, Ji Hyun Kim, Sanjeev Kumar, Vineet Kumar, Ajay Kumar, Ekaterina Kuznetsova, Ho Ling Li, Wei Li, Shuai Liu, Hao Liu, Werner Lustermann, Matteo Marone, Thomas Muller, Ioannis Papadopoulos, Vladimir Petrov, Andrea Rizzi, Paolo Ronchese, Sourav Sen, Varun Sharma, Ashish Sharma, Lesya Shchutska, Muhammad Shoaib, Michal Simon, Gurpreet Singh, Jan Steggemann, Wei Sun, Andromachi Tsirou, Paul Turner, Joao Varela, Jian Wang, Xiao Wang, Mingkui Wang, Zheng Wang, Qian Wang, Matthias Weber, Matthias Wolf, Wenjing Wu, Fan Yang, Yong Yang, Kai Yi, Lei Zhang, Yu Zheng

A search for physics beyond the standard model in events with at least three leptons is presented. The data sample, corresponding to an integrated luminosity of 19.5 fb-1 of proton-proton collisions with center-of-mass energy s=8 TeV, was collected by the CMS experiment at the LHC during 2012. The data are divided into exclusive categories based on the number of leptons and their flavor, the presence or absence of an opposite-sign, same-flavor lepton pair (OSSF), the invariant mass of the OSSF pair, the presence or absence of a tagged bottom-quark jet, the number of identified hadronically decaying τ leptons, and the magnitude of the missing transverse energy and of the scalar sum of jet transverse momenta. The numbers of observed events are found to be consistent with the expected numbers from standard model processes, and limits are placed on new-physics scenarios that yield multilepton final states. In particular, scenarios that predict Higgs boson production in the context of supersymmetric decay chains are examined. We also place a 95% confidence level upper limit of 1.3% on the branching fraction for the decay of a top quark to a charm quark and a Higgs boson (t→cH), which translates to a bound on the left- and right-handed top-charm flavor-violating Higgs Yukawa couplings, λtcH and λctH, respectively, of |λtcH|2+|λctH|2<0.21.

2014

Chargement