scholarly journals Search for new non-resonant phenomena in high-mass dilepton final states with the ATLAS detector

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
G. Aad ◽  
◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
...  
Keyword(s):  
Contact Interaction ◽  
Hadron Collider ◽  
Mass Range ◽  
New Physics ◽  
Mass Region ◽  
Mass Scale ◽  
Energy Scale ◽  
High Mass ◽  
Final States ◽  
Dilepton Final States

Abstract A search for new physics with non-resonant signals in dielectron and dimuon final states in the mass range above 2 TeV is presented. This is the first search for non-resonant signals in dilepton final states at the LHC to use a background estimate from the data. The data, corresponding to an integrated luminosity of 139 fb−1, were recorded by the ATLAS experiment in proton-proton collisions at a center-of-mass energy of $$ \sqrt{s} $$ s = 13 TeV during Run 2 of the Large Hadron Collider. The benchmark signal signature is a two-quark and two-lepton contact interaction, which would enhance the dilepton event rate at the TeV mass scale. To model the contribution from background processes a functional form is fit to the dilepton invariant-mass spectra in data in a mass region below the region of interest. It is then extrapolated to a high-mass signal region to obtain the expected background there. No significant deviation from the expected background is observed in the data. Upper limits at 95% CL on the number of events and the visible cross-section times branching fraction for processes involving new physics are provided. Observed (expected) 95% CL lower limits on the contact interaction energy scale reach 35.8 (37.6) TeV.

scholarly journals Erratum: Search for new non-resonant phenomena in high-mass dilepton final states with the ATLAS detector

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
G. Aad ◽  
◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
...  
Keyword(s):  
Atlas Detector ◽  
High Mass ◽  
Final States ◽  
Dilepton Final States ◽  
Resonant Phenomena

The Lagrangian in eq. (2.1) of JHEP11 (2020) 005 has an erroneous factor of 1/2. The analysis code used for the results reported in the paper does not have this factor. The results remain unchanged.

scholarly journals TRANSIENT ASTROPHYSICAL PULSES AND QUANTUM GRAVITY

2008 ◽  
Vol 17 (13n14) ◽  
pp. 2495-2500 ◽  
Author(s):  
MICHAEL KAVIC ◽  
DJORDJE MINIC ◽  
JOHN H. SIMONETTI
Keyword(s):  
Black Hole ◽  
Large Hadron Collider ◽  
Quantum Gravity ◽  
Extra Dimension ◽  
Hadron Collider ◽  
New Physics ◽  
Energy Scale ◽  
Primordial Black Hole ◽  
Fundamental Physics ◽  
Near Future

Searches for transient astrophysical pulses could open an exciting new window into the fundamental physics of quantum gravity. In particular, an evaporating primordial black hole in the presence of an extra dimension can produce a detectable transient pulse. Observations of such a phenomenon can in principle explore the electroweak energy scale, indicating that astrophysical probes of quantum gravity can successfully complement the exciting new physics expected to be discovered in the near future at the Large Hadron Collider.

scholarly journals Prospects of direct search for dark photon and dark Higgs in SeaQuest/E1067 experiment at the Fermilab main injector

2017 ◽  
Vol 32 (10) ◽  
pp. 1730008 ◽  
Author(s):  
Ming Xiong Liu
Keyword(s):  
Mass Range ◽  
High Energy ◽  
New Physics ◽  
Mass Region ◽  
Electromagnetic Calorimeter ◽  
Current Status ◽  
Dark Sector ◽  
Dark Photon ◽  
Near Future ◽  
Search Program

In this review, we present the current status and prospects of the dark sector physics search program of the SeaQuest/E1067 fixed target dimuon experiment at Fermilab Main Injector. There has been tremendous excitement and progress in searching for new physics in the dark sector in recent years. Dark sector refers to a collection of currently unknown particles that do not directly couple with the Standard Model (SM) strong and electroweak (EW) interactions but assumed to carry gravitational force, thus could be candidates of the missing Dark Matter (DM). Such particles may interact with the SM particles through “portal” interactions. Two of the simple possibilities are being investigated in our initial search: (1) dark photon and (2) dark Higgs. They could be within immediate reach of current or near future experimental search. We show there is a unique opportunity today at Fermilab to directly search for these particles in a highly motivated but uncharted parameter space in high-energy proton–nucleus collisions in the beam-dump mode using the 120 GeV proton beam from the Main Injector. Our current search window covers the mass range 0.2–10 GeV/c2, and in the near future, by adding an electromagnetic calorimeter (EMCal) to the spectrometer, we can further explore the lower mass region down to about [Formula: see text][Formula: see text]1 MeV/c2 through the di-electron channel. If dark photons (and/or dark Higgs) were observed, they would revolutionize our understanding of the fundamental structures and interactions of our universe.

scholarly journals U(3)C×Sp(1)L×U(1)L×U(1)R

2012 ◽  
Vol 2012 ◽  
pp. 1-43 ◽  
Author(s):  
Luis Alfredo Anchordoqui
Keyword(s):  
Gauge Theory ◽  
Cross Sections ◽  
Hadron Collider ◽  
Baryon Number ◽  
New Physics ◽  
Mass Scale ◽  
Gauge Bosons ◽  
Open Strings ◽  
Fundamental String ◽  
Discovery Potential

We outline the basic setting of theU(3)C×Sp(1)L×U(1)L×U(1)Rgauge theory and review the associated phenomenological aspects related to experimental searches for new physics at hadron colliders. In this construction, there are two massiveZ′-gauge bosons, which can be naturally associated with baryon numberB  and  B-L  (Lbeing lepton number). We discuss the potential signals which may be accessible at the Tevatron and at the Large Hadron Collider (LHC). In particular, we provide the relevant cross sections for the production ofZ′-gauge bosons in the TeV region, leading to predictions that are within reach of the present or the next LHC run. After that we direct attention to embedding the gauge theory into the framework of string theory. We consider extensions of the standard model based on open strings ending on D-branes, with gauge bosons due to strings attached to stacks of D-branes and chiral matter due to strings stretching between intersecting D-branes. Assuming that the fundamental string mass scale is in the TeV range and the theory is weakly coupled, we explore the LHC discovery potential for Regge excitations.

scholarly journals Real-time discrimination of photon pairs using machine learning at the LHC

2019 ◽  
Vol 7 (5) ◽  
Author(s):  
Sean Benson ◽  
Adrián Casais Vidal ◽  
Xabier Cid Vidal ◽  
Albert Puig Navarro
Keyword(s):  
Real Time ◽  
High Efficiency ◽  
Hadron Collider ◽  
Mass Range ◽  
Final States ◽  
Lhcb Experiment ◽  
Time Discrimination ◽  
Photon Pairs ◽  
Selection Framework ◽  
Time Selection

ALP–mediated decays and other as-yet unobserved B decays to di-photon final states are a challenge to select in hadron collider environments due to the large backgrounds that come directly from the pp collision. We present the strategy implemented by the LHCb experiment in 2018 to efficiently select such photon pairs. A fast neural network topology, implemented in the LHCb real-time selection framework achieves high efficiency across a mass range of 4–20GeV/c^22. We discuss implications and future prospects for the LHCb experiment.

scholarly journals Bounds on dark matter annihilation cross-sections from inert doublet model in the context of 21-cm cosmology of dark ages

2021 ◽  
pp. 2150163
Author(s):  
Rupa Basu ◽  
Madhurima Pandey ◽  
Debasish Majumdar ◽  
Shibaji Banerjee
Keyword(s):  
Dark Matter ◽  
Cross Sections ◽  
Mass Range ◽  
Mass Region ◽  
High Mass ◽  
Dark Matter Annihilation ◽  
Dark Ages ◽  
Doublet Model ◽  
Inert Doublet Model ◽  
Text Signal

We study the fluctuations in the brightness temperature of 21-cm signal [Formula: see text] at the dark ages ([Formula: see text]) with a dark matter (DM) candidate in Inert Doublet Model (IDM). We then explore the effects of different fractions of IDM DM on [Formula: see text] signal. The IDM DM masses are chosen in few tens of GeV region as well as in the high mass region beyond 500 GeV. It has been observed that the [Formula: see text] signal is more sensitive in the DM mass range of 70–80 GeV. A lower bound on annihilation cross-section for this DM is also obtained by analyzing the [Formula: see text] signal. This is found to lie within the range [Formula: see text] cm3/s for the IDM DM mass range 10 GeV[Formula: see text] GeV.

scholarly journals Search for Heavy Higgs Bosons with the ATLAS Detector

2018 ◽  
Vol 46 ◽  
pp. 1860056
Author(s):  
Jana Schaarschmidt
Keyword(s):  
Large Hadron Collider ◽  
Cross Section ◽  
Production Cross Section ◽  
Production Cross ◽  
Hadron Collider ◽  
New Physics ◽  
Atlas Detector ◽  
Higgs Bosons ◽  
Final States ◽  
Atlas Experiment

The ATLAS experiment at the Large Hadron Collider performed searches for heavy Higgs bosons, whose presence would establish the existance of new physics. Searches for charged and neutral Higgs bosons are carried out using 8 or 13 TeV data for various production modes and in many different final states. No deviations from Standard Model expectations are observed. Exclusions limits are set on the production cross section and on parameters in various benchmark models.

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