scholarly journals EVENTS WITH ISOLATED CHARGED LEPTONS AND LARGE MISSING TRANSVERSE MOMENTUM AT HERA

2004 ◽  
Vol 19 (25) ◽  
pp. 1881-1902 ◽  
Author(s):  
TANCREDI CARLI ◽  
DOMINIK DANNHEIM ◽  
LORENZO BELLAGAMBA
Keyword(s):  
Transverse Momentum ◽  
Zeus Collaboration ◽  
Tau Leptons ◽  
High Luminosity ◽  
Final State ◽  
Missing Transverse Momentum ◽  
State Formula ◽  
Charged Leptons ◽  
Good Agreement ◽  
Event Topology

Striking events with isolated charged leptons, large missing transverse momentum and large transverse momentum of the hadronic final state [Formula: see text] were observed at the electron proton collider HERA in a data sample corresponding to an integrated luminosity of about 130 pb-1. The H1 collaboration observed 11 events with isolated electrons or muons and with [Formula: see text]. Only 3.4±0.6 events were expected from Standard Model (SM) processes. Six of these events have [Formula: see text], while 1.3±0.3 events were expected. The ZEUS collaboration observed good agreement with the SM. However, ZEUS found two events with a similar event topology, but tau leptons instead of electrons or muons in the final state. Only 0.2±0.05 events were expected from SM processes. For various hypotheses, the compatibility of the experimental results was investigated with respect to the SM and with respect to possible explanations beyond the SM. Prospects for the high-luminosity HERA-II data taking period are given.

Implementation of the CMS-SUS-19-006 analysis in the MadAnalysis 5 framework (supersymmetry with large hadronic activity and missing transverse energy; 137 fb−1)

2020 ◽  
pp. 2141007
Author(s):  
Malte Mrowietz ◽  
Sam Bein ◽  
Jory Sonneveld
Keyword(s):  
Transverse Momentum ◽  
Transverse Energy ◽  
Final States ◽  
Missing Transverse Energy ◽  
Final State ◽  
Data Set ◽  
Proton Proton ◽  
Missing Transverse Momentum ◽  
Proton Data ◽  
Two Jets

We present the MadAnalysis 5 implementation and validation of the analysis Search for supersymmetry in proton-proton collisions at 13 TeV in final states with jets and missing transverse momentum (CMS-SUS-19-006). The search targets signatures with at least two jets and large missing transverse momentum in the all-hadronic final state. The analyzed luminosity is 137 fb[Formula: see text], corresponding to the Run 2 proton-proton data set recorded by the CMS detector at 13 TeV. This implementation has been validated in a variety of simplified models, by comparing derived cut flow tables and histograms with information provided by the CMS collaboration, using event samples that we simulated for the purpose of this re-implementation study. The validation is found to reproduce the signal acceptance in most cases.

scholarly journals Search for supersymmetry in the multijet and missing transverse momentum final state in pp collisions at 13 TeV

2016 ◽  
Vol 758 ◽  
pp. 152-180 ◽  
Author(s):  
V. Khachatryan ◽  
A.M. Sirunyan ◽  
A. Tumasyan ◽  
W. Adam ◽  
E. Asilar ◽  
...  
Keyword(s):  
Transverse Momentum ◽  
Pp Collisions ◽  
Final State ◽  
Missing Transverse Momentum

scholarly journals Search for top squark pair production using dilepton final states in $${\text {p}}{\text {p}}$$ collision data collected at $$\sqrt{s}=13\,\text {TeV} $$

2021 ◽  
Vol 81 (1) ◽  
Author(s):  
A. M. Sirunyan ◽  
◽  
A. Tumasyan ◽  
W. Adam ◽  
F. Ambrogi ◽  
...  
Keyword(s):  
Transverse Momentum ◽  
Pair Production ◽  
Top Quark ◽  
Transverse Mass ◽  
Final States ◽  
Top Squark ◽  
Missing Transverse Momentum ◽  
Charged Leptons ◽  
The Masses ◽  
Lower Limits

AbstractA search is presented for supersymmetric partners of the top quark (top squarks) in final states with two oppositely charged leptons (electrons or muons), jets identified as originating from $${\text {b}}$$ b quarks, and missing transverse momentum. The search uses data from proton-proton collisions at $$\sqrt{s}=13\,\text {TeV} $$ s = 13 TeV collected with the CMS detector, corresponding to an integrated luminosity of 137$$\,{\text {fb}}^{-1}$$ fb - 1 . Hypothetical signal events are efficiently separated from the dominant top quark pair production background with requirements on the significance of the missing transverse momentum and on transverse mass variables. No significant deviation is observed from the expected background. Exclusion limits are set in the context of simplified supersymmetric models with pair-produced lightest top squarks. For top squarks decaying exclusively to a top quark and a lightest neutralino, lower limits are placed at $$95\%$$ 95 % confidence level on the masses of the top squark and the neutralino up to 925 and 450$$\,\text {GeV}$$ GeV , respectively. If the decay proceeds via an intermediate chargino, the corresponding lower limits on the mass of the lightest top squark are set up to 850$$\,\text {GeV}$$ GeV for neutralino masses below 420$$\,\text {GeV}$$ GeV . For top squarks undergoing a cascade decay through charginos and sleptons, the mass limits reach up to 1.4$$\,\text {TeV}$$ TeV and 900$$\,\text {GeV}$$ GeV respectively for the top squark and the lightest neutralino.

scholarly journals Search for a scalar partner of the top quark in the all-hadronic $$t{\bar{t}}$$ plus missing transverse momentum final state at $$\sqrt{s}=13$$ TeV with the ATLAS detector

2020 ◽  
Vol 80 (8) ◽  
Author(s):  
G. Aad ◽  
◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
...  
Keyword(s):  
Transverse Momentum ◽  
Top Quark ◽  
Atlas Detector ◽  
Supersymmetric Model ◽  
Proton Collision ◽  
Third Generation ◽  
Final State ◽  
Top Squark ◽  
Missing Transverse Momentum ◽  
200 Gev

Abstract A search for direct pair production of scalar partners of the top quark (top squarks or scalar third-generation up-type leptoquarks) in the all-hadronic $$t{\bar{t}}$$tt¯ plus missing transverse momentum final state is presented. The analysis of 139 $$\hbox {fb}^{-1}$$fb-1 of $${\sqrt{s}=13}$$s=13 TeV proton–proton collision data collected using the ATLAS detector at the LHC yields no significant excess over the Standard Model background expectation. To interpret the results, a supersymmetric model is used where the top squark decays via $${\tilde{t}} \rightarrow t^{(*)} {\tilde{\chi }}^0_1$$t~→t(∗)χ~10, with $$t^{(*)}$$t(∗) denoting an on-shell (off-shell) top quark and $${\tilde{\chi }}^0_1$$χ~10 the lightest neutralino. Three specific event selections are optimised for the following scenarios. In the scenario where $$m_{{\tilde{t}}}> m_t+m_{{\tilde{\chi }}^0_1}$$mt~>mt+mχ~10, top squark masses are excluded in the range 400–1250 GeV for $${\tilde{\chi }}^0_1$$χ~10 masses below 200 GeV at 95% confidence level. In the situation where $$m_{{\tilde{t}}}\sim m_t+m_{{\tilde{\chi }}^0_1}$$mt~∼mt+mχ~10, top squark masses in the range 300–630 GeV are excluded, while in the case where $$m_{{\tilde{t}}}< m_W+m_b+m_{{\tilde{\chi }}^0_1}$$mt~<mW+mb+mχ~10 (with $$m_{{\tilde{t}}}-m_{{\tilde{\chi }}^0_1}\ge 5$$mt~-mχ~10≥5 GeV), considered for the first time in an ATLAS all-hadronic search, top squark masses in the range 300–660 GeV are excluded. Limits are also set for scalar third-generation up-type leptoquarks, excluding leptoquarks with masses below 1240 GeV when considering only leptoquark decays into a top quark and a neutrino.

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