scholarly journals Prospects for Higgs Boson Measurements and Beyond Standard Model Physics at the High-Luminosity LHC with CMS

2018 ◽  
Vol 192 ◽  
pp. 00032 ◽  
Author(s):  
Rosamaria Venditti

The High-Luminosity Large Hadron Collider (HL-LHC) is a major upgrade of the LHC, expected to deliver an integrated luminosity of up to 3000/fb over one decade. The very high instantaneous luminosity will lead to about 200 proton-proton collisions per bunch crossing (pileup) superimposed to each event of interest, therefore providing extremely challenging experimental conditions. The scientific goals of the HL-LHC physics program include precise measurement of the properties of the recently discovered standard model Higgs boson and searches for beyond the standard model physics (heavy vector bosons, SUSY, dark matter and exotic long-lived signatures, to name a few). In this contribution we will present the strategy of the CMS experiment to investigate the feasibility of such search and quantify the increase of sensitivity in the HL-LHC scenario.

2013 ◽  
Vol 28 (16) ◽  
pp. 1330026
Author(s):  
STEVE NAHN ◽  
DMITRI TSYBYCHEV

The large hadron collider (LHC) physics program is finally on the way to help uncover the mechanism responsible for electroweak symmetry breaking, with each of experiments collecting up to 5 fb-1 of data at center-of-mass energy of 7 TeV. In this review, we summarize searches for physics beyond the Standard Model at ATLAS and CMS experiments at LHC.


2020 ◽  
Vol 18 ◽  
pp. 110-142
Author(s):  
Abdeljalil Habjia

In the context of particle physics, within the ATLAS and CMS experiments at large hadron collider (LHC), this work presents the discussion of the discovery of a particle compatible with the Higgs boson by the combination of several decay channels, with a mass of the order of 125.5 GeV. With increased statistics, that is the full set of data collected by the ATLAS and CMS experiments at LHC ( s1/2 = 7GeV and s1/2 = 8GeV ), the particle is also discovered individually in the channel h-->γγ with an observed significance of 5.2σ and 4.7σ, respectively. The analysis dedicated to the measurement of the mass mh and signal strength μ which is defined as the ratio of σ(pp --> h) X Br(h-->X) normalized to its Standard Model where X = WW*; ZZ*; γγ ; gg; ff. The combined results in h-->γγ channel gave the measurements: mh = 125:36 ± 0:37Gev, (μ = 1:17 ± 0:3) and the constraint on the width Γ(h) of the Higgs decay of 4.07 MeV at 95%CL. The spin study rejects the hypothesis of spin 2 at 99 %CL. The odd parity (spin parity 0- state) is excluded at more than 98%CL. Within the theoretical and experimental uncertainties accessible at the time of the analysis, all results: channels showing the excess with respect to the background-only hypothesis, measured mass and signal strength, couplings, quantum numbers (JPC), production modes, total and differential cross-sections, are compatible with the Standard Model Higgs boson at 95%CL. Although the Standard Model is one of the theories that have experienced the greatest number of successes to date, it is imperfect. The inability of this model to describe certain phenomena seems to suggest that it is only an approximation of a more general theory. Models beyond the Standard Model, such as 2HDM, MSSM or NMSSM, can compensate some of its limitations and postulate the existence of additional Higgs bosons.


2008 ◽  
Vol 23 (06) ◽  
pp. 823-834 ◽  
Author(s):  
SANTOSH KUMAR RAI

A major focus at the Large Hadron Collider (LHC) will be on Higgs boson studies and it would be an interesting prospect to simultaneously probe for physics beyond the Standard Model in the Higgs signals. In this work we show as to what extent, the effects of universal extra dimension (UED) can be isolated at the LHC through the Higgs signals. By doing a detailed study of the different uncertainties involved in the measurement of the rates for the process pp →h →γγ, we estimate the extent to which these uncertainties can mask the effects of the contributions coming from UED.


2020 ◽  
Vol 80 (10) ◽  
Author(s):  
Henning Bahl ◽  
Philip Bechtle ◽  
Sven Heinemeyer ◽  
Stefan Liebler ◽  
Tim Stefaniak ◽  
...  

AbstractThe prediction of additional Higgs bosons is one of the key features of physics beyond the Standard Model (SM) that gives rise to an extended Higgs sector. We assess the sensitivity of the Large Hadron Collider (LHC) in the high luminosity (HL) run alone and in combination with a possible future International Linear Collider (ILC) to probe heavy neutral Higgs bosons. We employ the Minimal Supersymmetric Standard Model (MSSM) as a framework and assume the light $$\mathcal {CP}$$ CP -even MSSM Higgs boson to be the Higgs boson observed at $$125\,\mathrm{GeV}$$ 125 GeV . We discuss the constraints on the MSSM parameter space arising from the precision measurements of the rates of the detected signal at $$125\,\mathrm{GeV}$$ 125 GeV and from direct searches for new heavy Higgs bosons in the $$\tau ^+\tau ^-$$ τ + τ - , $$b\bar{b}$$ b b ¯ and di-Higgs (hh) final states. A new benchmark scenario for heavy Higgs searches in the $$b\bar{b}$$ b b ¯ channel is proposed in this context. For the future Higgs rate measurements at the HL-LHC and ILC two different scenarios are investigated, namely the case where the future rate measurements agree with the SM prediction and the case where the rates agree with the predictions of possible realizations of the MSSM Higgs sector in nature.


2020 ◽  
Vol 80 (10) ◽  
Author(s):  
G. Aad ◽  
◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
...  

AbstractInclusive and differential fiducial cross sections of the Higgs boson are measured in the $$H \rightarrow ZZ^{*} \rightarrow 4\ell $$ H → Z Z ∗ → 4 ℓ ($$\ell = e,\mu $$ ℓ = e , μ ) decay channel. The results are based on proton−proton collision data produced at the Large Hadron Collider at a centre-of-mass energy of 13 TeV and recorded by the ATLAS detector from 2015 to 2018, equivalent to an integrated luminosity of 139 $$\hbox {fb}^{-1}$$ fb - 1 . The inclusive fiducial cross section for the $$H \rightarrow ZZ^{*} \rightarrow 4\ell $$ H → Z Z ∗ → 4 ℓ process is measured to be $$\sigma _\mathrm {fid} = 3.28 \pm 0.32$$ σ fid = 3.28 ± 0.32  fb, in agreement with the Standard Model prediction of $$\sigma _\mathrm {fid, SM} = 3.41 \pm 0.18 $$ σ fid , SM = 3.41 ± 0.18  fb. Differential fiducial cross sections are measured for a variety of observables which are sensitive to the production and decay of the Higgs boson. All measurements are in agreement with the Standard Model predictions. The results are used to constrain anomalous Higgs boson interactions with Standard Model particles.


2007 ◽  
Vol 22 (27) ◽  
pp. 5039-5051
Author(s):  
GEOFFREY N. TAYLOR

In this paper an overview of the Large Hadron Collider program and status is given, including a brief description of the scientific background from which this ambitious program evolved. The emphasis is on the status of the Standard Model Higgs Boson, searches for which are the key component of the LHC program. A description of the ATLAS one of the two large general purpose experiments designed to detect evidence for the Higgs Boson and other data of interest to searches for physics beyond the standard model.


Author(s):  
Pippa S. Wells

The update of the European Strategy for Particle Physics from 2013 states that Europe's top priority should be the exploitation of the full potential of the LHC, including the high-luminosity upgrade of the machine and detectors with a view to collecting 10 times more data than in the initial design. The plans for upgrading the ATLAS and CMS detectors so as to maintain their performance and meet the challenges of increasing luminosity are presented here. A cornerstone of the physics programme is to measure the properties of the 125 GeV Higgs boson with the highest possible precision, to test its consistency with the Standard Model. The high-luminosity data will allow precise measurements of the dominant production and decay modes, and offer the possibility of observing rare modes including Higgs boson pair production. Direct and indirect searches for additional Higgs bosons beyond the Standard Model will also continue.


Author(s):  
John Ellis

The Standard Model of particle physics agrees very well with experiment, but many important questions remain unanswered, among them are the following. What is the origin of particle masses and are they due to a Higgs boson? How does one understand the number of species of matter particles and how do they mix? What is the origin of the difference between matter and antimatter, and is it related to the origin of the matter in the Universe? What is the nature of the astrophysical dark matter? How does one unify the fundamental interactions? How does one quantize gravity? In this article, I introduce these questions and discuss how they may be addressed by experiments at the Large Hadron Collider, with particular attention to the search for the Higgs boson and supersymmetry.


2016 ◽  
Vol 31 (32) ◽  
pp. 1630058
Author(s):  
Tejinder Singh Virdee

Since 2010 there has been a rich harvest of results on standard model physics by the ATLAS and CMS experiments operating on the Large Hadron Collider. In the summer of 2012, a spectacular discovery was made by these experiments of a new, heavy particle. All the subsequently analysed data point strongly to the properties of this particle as those expected for the Higgs boson associated with the Brout–Englert–Higgs mechanism postulated to explain the spontaneous symmetry breaking in the electroweak sector, thereby explaining how elementary particles acquire mass. This article focuses on the CMS experiment, the technological challenges encountered in its construction, describing some of the physics results obtained so far, including the discovery of the Higgs boson, and searches for the widely anticipated new physics beyond the standard model, and peer into the future involving the high-luminosity phase of the LHC. This article is complementary to the one by Peter Jenni4 that focuses on the ATLAS experiment.


2016 ◽  
Vol 31 (04n05) ◽  
pp. 1650005 ◽  
Author(s):  
O. M. Boyarkin ◽  
G. G. Boyarkina

Two most popular GUT scenarios, namely, the left–right symmetric model (LRM) and models coming from [Formula: see text] grand unification (effective rank 5 models (ER5M’s)) are considered. Both models forecast existence of the extra neutral gauge boson. Its contributions to the decay of the Higgs boson being an analog of the Standard Model (SM) Higgs boson [Formula: see text] and the process of the associated Higgs production with [Formula: see text] boson (Higgsstrahlung) [Formula: see text] are found. For both processes, deviations from the SM predicted by the LRM prove to be larger than that predicted by the ER5M’s. It is shown that in the case of the decay [Formula: see text] it is impossible to observe these deviations at the condition of the High Luminosity Large Hadron Collider. Investigation of the Higgsstrahlung disclosed that with its help one could make a choice between the SM and the SM extensions under consideration.


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