2019:groups:higgs:lightscalars
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2019:groups:higgs:lightscalars [2019/06/27 13:39] shilpi.jain |
2019:groups:higgs:lightscalars [2019/06/28 09:09] jonathan.butterworth |
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| Below 80-90GeV, for a generic (pseudo-)scalar $\phi$ (light Higgs, radion, dilaton, axion, ALP's...), the decay $\phi$ → Z*Z is kinematically closed and $\phi$ → $\gamma\gamma$ becomes challenging to trigger on, so that the gluon-gluon Fusion mechanism to produce $\phi$ is not promising anymore (see for instance [[https://arxiv.org/abs/1607.08653|1607.08653]]). | Below 80-90GeV, for a generic (pseudo-)scalar $\phi$ (light Higgs, radion, dilaton, axion, ALP's...), the decay $\phi$ → Z*Z is kinematically closed and $\phi$ → $\gamma\gamma$ becomes challenging to trigger on, so that the gluon-gluon Fusion mechanism to produce $\phi$ is not promising anymore (see for instance [[https://arxiv.org/abs/1607.08653|1607.08653]]). | ||
| - | * Quick contur study using the BNT ALP UFO file. All couplings set to zero except the photons which is scanned over. {{ :2019:groups:higgs:combinedhybrid.pdf | 2D scan }}. Over a wide range of $\phi$ masses ($M_{ALP}$ on the plot) the sensitivity extends down to $C_{\gamma\gamma}/\Lambda \approx 3$ TeV$^{-1}$. | + | * Quick contur study using the BNT ALP UFO file. All couplings set to zero except the photons which is scanned over. {{ :2019:groups:higgs:combinedhybrid.pdf | 2D scan }}. Over a wide range of $\phi$ masses ($M_{ALP}$ on the plot) the sensitivity extends down to $C_{\gamma\gamma}/\Lambda \approx 3$ TeV$^{-1}$. Here the scan is performed over the following ranges: $m_a:$ 1 to 50 GeV, $g_{a\gamma\gamma}$: 10 to $10^{-6}$, $g_{aZ\gamma}$: 10 to $10^{-6}$ |
| - | + | ||
| * Checking at an example point in the above scan, $M_{ALP} = 1.8$ GeV, $C_{\gamma\gamma}/\Lambda = 5.2$ TeV$^{-1}$, all other couplings set to zero. The $\phi$ decays 100% to $\gamma\gamma$ as expected (width $10^{-7}$ GeV). The main production mechanisms are $\gamma, W$ or $Z$ + $\phi$. $gg \rightarrow \phi$ is zero. The different subprocess cross sections are visible in the example Herwig output file: {{ :2019:groups:higgs:lhc-s101-runpoint_0095.out.txt | lhc-s101-runpoint_0095.out}} | * Checking at an example point in the above scan, $M_{ALP} = 1.8$ GeV, $C_{\gamma\gamma}/\Lambda = 5.2$ TeV$^{-1}$, all other couplings set to zero. The $\phi$ decays 100% to $\gamma\gamma$ as expected (width $10^{-7}$ GeV). The main production mechanisms are $\gamma, W$ or $Z$ + $\phi$. $gg \rightarrow \phi$ is zero. The different subprocess cross sections are visible in the example Herwig output file: {{ :2019:groups:higgs:lhc-s101-runpoint_0095.out.txt | lhc-s101-runpoint_0095.out}} | ||
| + | * Some more scans as suggested by Aoife and Jose: | ||
| + | * {{:2019:groups:higgs:combinedhybrid50.png?200|}} | ||
| + | * {{:2019:groups:higgs:combinedhybrid30.png?200|}} | ||
| + | * {{:2019:groups:higgs:combinedhybrid10.png?200|}} | ||
| For instance, Higgs composite models with additional light scalars:[[https://arxiv.org/pdf/1810.11142.pdf|1710.11142]], [[https://arxiv.org/pdf/1902.08690.pdf|1902.08690]]. | For instance, Higgs composite models with additional light scalars:[[https://arxiv.org/pdf/1810.11142.pdf|1710.11142]], [[https://arxiv.org/pdf/1902.08690.pdf|1902.08690]]. | ||
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| * ... | * ... | ||
| - | Promising DECAYS: $\phi\to\gamma\gamma$ (and $\mu\mu$, $bb$, $\tau\tau$, Missing E_T ?) [names: **TF**] | + | Promising DECAYS: $\phi\to\gamma\gamma$ (and $\mu\mu$, $bb$, $\tau\tau$, Missing E_T ?) [names: **TF, JZ**] |
| General comment: If the particle is lighter than hadronic threshold ($m_a <3m_\pi<450\rm MeV$ for CP-odd scalar), the particle is easily long-lived in the reasonable parameter space. Many literature ignores loop-factor $16\pi^2$, which sometimes leads to less physical parameter space. A scale $\Lambda/C_{\gamma\gamma}=1\rm TeV$ in [[https://arxiv.org/abs/1708.00443|1708.00443]] parameterization corresponds to a scale $f_a =6\rm GeV$ in the decay constant (SSB scale).So ALP being invisible is quite possible with sub-GeV mass and $f_a >100\rm GeV$. Estimates with ALP as missing energy in [[https://arxiv.org/abs/1409.4792|1409.4792]] (mono-jet), [[https://arxiv.org/abs/1701.05379|1701.05379]] (mono-W, mono-Z, mono-Higgs) and [[https://arxiv.org/abs/1901.03061|1901.03061]]. | General comment: If the particle is lighter than hadronic threshold ($m_a <3m_\pi<450\rm MeV$ for CP-odd scalar), the particle is easily long-lived in the reasonable parameter space. Many literature ignores loop-factor $16\pi^2$, which sometimes leads to less physical parameter space. A scale $\Lambda/C_{\gamma\gamma}=1\rm TeV$ in [[https://arxiv.org/abs/1708.00443|1708.00443]] parameterization corresponds to a scale $f_a =6\rm GeV$ in the decay constant (SSB scale).So ALP being invisible is quite possible with sub-GeV mass and $f_a >100\rm GeV$. Estimates with ALP as missing energy in [[https://arxiv.org/abs/1409.4792|1409.4792]] (mono-jet), [[https://arxiv.org/abs/1701.05379|1701.05379]] (mono-W, mono-Z, mono-Higgs) and [[https://arxiv.org/abs/1901.03061|1901.03061]]. | ||
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| {{ :2019:groups:higgs:alp-pr.tar.gz |ALP UFO file }} from [[https://arxiv.org/abs/1708.00443|Bauer, Neubert, Thamm]] with fix for the ALP mass / Higgs/ Z mass bug from Peter Richardson. | {{ :2019:groups:higgs:alp-pr.tar.gz |ALP UFO file }} from [[https://arxiv.org/abs/1708.00443|Bauer, Neubert, Thamm]] with fix for the ALP mass / Higgs/ Z mass bug from Peter Richardson. | ||
| - | {{ :2019:groups:higgs:alp_chiral_ufo_v2.tar.gz |ALP UFO file }} from [[https://arxiv.org/abs/1701.05379|Brivio, Gavela, Merlo, Mimasu, No, del Rey, Sanz]] (with fix for the ALP width). | + | {{ :2019:groups:higgs:alp_chiral_ufo_v2.tar.gz |ALP UFO file }} from [[https://arxiv.org/abs/1701.05379|1701.05379]] (Brivio, Gavela, Merlo, Mimasu, No, del Rey, Sanz) (with fix for the ALP width). |
| + | |||
| {{ :2019:groups:higgs:alp_linear_ufo.tar.gz | ALP linear UFO file }} from [[https://arxiv.org/abs/1701.05379|Brivio, Gavela, Merlo, Mimasu, No, del Rey, Sanz]] (also with fix for the ALP width - GP). | {{ :2019:groups:higgs:alp_linear_ufo.tar.gz | ALP linear UFO file }} from [[https://arxiv.org/abs/1701.05379|Brivio, Gavela, Merlo, Mimasu, No, del Rey, Sanz]] (also with fix for the ALP width - GP). | ||
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| * Z*-->Zphi-->llgamma or gammaphi-->3gamma | * Z*-->Zphi-->llgamma or gammaphi-->3gamma | ||
| * (Above 2 with 'Bauer et al.' model) | * (Above 2 with 'Bauer et al.' model) | ||
| - | * h*-->Zphi-->llgamma gamma (derive UFO from h*-->ZZ* with add'l functionality?) | + | * h*-->Zphi-->llgamma gamma (derive UFO from h*-->ZZ* with add'l functionality?) [**SJ**] |
| * qqbar/e+e--->Z*/gamma*-->Zphi-->llgamma gamma (started LH 2017) | * qqbar/e+e--->Z*/gamma*-->Zphi-->llgamma gamma (started LH 2017) | ||
| * qqbar-->Z*/gamma*-->phi + 2j (VBF version of above) | * qqbar-->Z*/gamma*-->phi + 2j (VBF version of above) | ||
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| * tprime--tphi, phi-->gamma gamma (singlet pseudo-scalar, composite Higgs) | * tprime--tphi, phi-->gamma gamma (singlet pseudo-scalar, composite Higgs) | ||
| - | * Theoretical: recasting as 2HDM | + | * Theoretical: recasting as 2HDM and other benchmark models [**JQ**] |
| * Experimental: | * Experimental: | ||
| * 'fat' photons [**SJ**] | * 'fat' photons [**SJ**] | ||
| - | *statistical tool to produce proto-limits after proto-selections [**SJ**] | + | *statistical tool to produce proto-limits after proto-selections [**SJ**]: Such a tool is now ready. This uses likelihood ratio as a test statistic i.e. L(s+b)/L(b). Uses Cls method to quote the upper limits which is commonly and widely used by CMS and ATLAS. This has been cross-checked against the CMS limit tool for cut and counting experiment. But the present code can be extended to do a shape based limit. |
| Contributions on the above projects to the Friday closing talk (by the Higgs convenors) should include (~1-2 slides): | Contributions on the above projects to the Friday closing talk (by the Higgs convenors) should include (~1-2 slides): | ||
2019/groups/higgs/lightscalars.txt · Last modified: 2019/06/28 11:15 by suzanne.gascon
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