Constraining sleptons at the LHC in a supersymmetric low-scale seesaw scenario
We consider a scenario inspired by natural supersymmetry, where neutrino data is explained within a low-scale seesaw scenario. We extend the Minimal Supersymmetric Standard Model by adding light right-handed neutrinos and their superpartners, the R-sneutrinos, and consider the lightest neutralinos to be higgsino-like. We consider the possibilities of having either an R-sneutrino or a higgsino as lightest supersymmetric particle. Assuming that squarks and gauginos are heavy, we systematically evaluate the bounds on slepton masses due to existing LHC data.
Año de publicación: 2017
We consider a scenario inspired by natural supersymmetry, where neutrino data is explained within a low-scale seesaw scenario. We extend the Minimal Supersymmetric Standard Model by adding light right-handed neutrinos and their superpartners, the R-sneutrinos, and consider the lightest neutralinos to be higgsino-like. We consider the possibilities of having either an R-sneutrino or a higgsino as lightest supersymmetric particle. Assuming that squarks and gauginos are heavy, we systematically evaluate the bounds on slepton masses due to existing LHC data.
Año de publicación: 2017
Visible neutrino decay in the light of appearance and disappearance long-baseline experiments
We investigate the present constraints from MINOS and T2K experiments for the neutrino decay scenario induced by non-diagonal couplings of Majorons to neutrinos. As novelty, on top of the typical invisible decay prescription, we add the contribution of visible decay, where final products can be observed. This new effect depends on the nature of the neutrino-Majoron coupling, which can be of scalar or pseudoscalar type. Using the combination of disappearance data from MINOS and disappearance and appearance data from T2K, for normal ordering, we constrain the decay parameter α ≡ E Γ for the heaviest neutrino, where E and Γ are the neutrino energy and width, respectively. We find that when considering visible decay within appearance data, one can improve current neutrino long-baseline constraints up to 𝛼<(10−5) eV2, at 90% C.L., for both kinds of couplings, which is better by one order of magnitude compared to previous bounds.
Año de publicación: 2017
We investigate the present constraints from MINOS and T2K experiments for the neutrino decay scenario induced by non-diagonal couplings of Majorons to neutrinos. As novelty, on top of the typical invisible decay prescription, we add the contribution of visible decay, where final products can be observed. This new effect depends on the nature of the neutrino-Majoron coupling, which can be of scalar or pseudoscalar type. Using the combination of disappearance data from MINOS and disappearance and appearance data from T2K, for normal ordering, we constrain the decay parameter α ≡ E Γ for the heaviest neutrino, where E and Γ are the neutrino energy and width, respectively. We find that when considering visible decay within appearance data, one can improve current neutrino long-baseline constraints up to 𝛼<(10−5) eV2, at 90% C.L., for both kinds of couplings, which is better by one order of magnitude compared to previous bounds.
Año de publicación: 2017
Testing FLUKA on neutron activation of Si and Ge at nuclear research reactor using gamma spectroscopy
Samples of two characteristic semiconductor sensor materials, silicon and germanium, have been irradiated with neutrons produced at the RP-10 Nuclear Research Reactor at 4.5 MW. Their radionuclides photon spectra have been measured with high resolution gamma spectroscopy, quantifying four radioisotopes (28Al, 29Al for Si and 75Ge and 77Ge for Ge). We have compared the radionuclides production and their emission spectrum data with Monte Carlo simulation results from FLUKA. Thus we have tested FLUKA’s low energy neutron library (ENDF/B-VIIR) and decay photon scoring with respect to the activation of these semiconductors. We conclude that FLUKA is capable of predicting relative photon peak amplitudes, with gamma intensities greater than 1%, of produced radionuclides with an average uncertainty of 13%. This work allows us to estimate the corresponding systematic error on neutron activation simulation studies of these sensor materials.
Año de publicación: 2017
Samples of two characteristic semiconductor sensor materials, silicon and germanium, have been irradiated with neutrons produced at the RP-10 Nuclear Research Reactor at 4.5 MW. Their radionuclides photon spectra have been measured with high resolution gamma spectroscopy, quantifying four radioisotopes (28Al, 29Al for Si and 75Ge and 77Ge for Ge). We have compared the radionuclides production and their emission spectrum data with Monte Carlo simulation results from FLUKA. Thus we have tested FLUKA’s low energy neutron library (ENDF/B-VIIR) and decay photon scoring with respect to the activation of these semiconductors. We conclude that FLUKA is capable of predicting relative photon peak amplitudes, with gamma intensities greater than 1%, of produced radionuclides with an average uncertainty of 13%. This work allows us to estimate the corresponding systematic error on neutron activation simulation studies of these sensor materials.
Año de publicación: 2017
Roadmap for searching cosmic rays correlated with the extraterrestrial neutrinos seen at IceCube
We have built sky maps showing the expected arrival directions of 120 EeV ultrahigh-energy cosmic rays (UHECRs) directionally correlated with the latest astrophysical neutrino tracks observed at IceCube, including the four-year high-energy starting events (HESEs) and the two-year northern tracks, taken as point sources. We have considered contributions to UHECR deflections from the Galactic and the extragalactic magnetic field and a UHECR composition compatible with the current expectations. We have used the Jansson-Farrar JF12 model for the Galactic magnetic field and an extragalactic magnetic field strength of 1 nG and coherence length of 1 Mpc. We observe that the regions outside of the Galactic plane are more strongly correlated with the neutrino tracks than those adjacent to or in it, where IceCube HESE events 37 and 47 are good candidates to search for excesses, or anisotropies, in the UHECR flux. On the other hand, clustered northern tracks around (l,b)=(0°,−30°) and (l,b)=(−150°,−30°) are promising candidates for a stacked point source search. For example, we have focused on the region of UHECR arrival directions, at 150 EeV, correlated with IceCube HESE event 37 located at (l,b)=(−137.1°,65.8°) in the northern hemisphere, far away from the Galactic plane, obtaining an angular size ∼5°, being ∼3° for 200 EeV and ∼8° for 120 EeV. We report a p value of 0.20 for a stacked point source search using current Auger and Telescope Array data, consistent with current results from both collaborations. Using Telescope Array data alone, we found a projected live time of 72 years to find correlations, but clearly this must improve with the planned Auger upgrade.
Año de publicación: 2017
We have built sky maps showing the expected arrival directions of 120 EeV ultrahigh-energy cosmic rays (UHECRs) directionally correlated with the latest astrophysical neutrino tracks observed at IceCube, including the four-year high-energy starting events (HESEs) and the two-year northern tracks, taken as point sources. We have considered contributions to UHECR deflections from the Galactic and the extragalactic magnetic field and a UHECR composition compatible with the current expectations. We have used the Jansson-Farrar JF12 model for the Galactic magnetic field and an extragalactic magnetic field strength of 1 nG and coherence length of 1 Mpc. We observe that the regions outside of the Galactic plane are more strongly correlated with the neutrino tracks than those adjacent to or in it, where IceCube HESE events 37 and 47 are good candidates to search for excesses, or anisotropies, in the UHECR flux. On the other hand, clustered northern tracks around (l,b)=(0°,−30°) and (l,b)=(−150°,−30°) are promising candidates for a stacked point source search. For example, we have focused on the region of UHECR arrival directions, at 150 EeV, correlated with IceCube HESE event 37 located at (l,b)=(−137.1°,65.8°) in the northern hemisphere, far away from the Galactic plane, obtaining an angular size ∼5°, being ∼3° for 200 EeV and ∼8° for 120 EeV. We report a p value of 0.20 for a stacked point source search using current Auger and Telescope Array data, consistent with current results from both collaborations. Using Telescope Array data alone, we found a projected live time of 72 years to find correlations, but clearly this must improve with the planned Auger upgrade.
Año de publicación: 2017
Impact of Galactic magnetic field modeling on searches of point sources via ultrahigh energy cosmic ray-neutrino correlations
We apply the Jansson-Farrar JF12 magnetic field model in the context of point source searches by correlating the Telescope Array ultrahigh energy cosmic ray data and the IceCube-40 neutrino candidates, as well as other magnetic field hypotheses. Our field hypotheses are: no magnetic field, the JF12 field considering only the regular component, the JF12 full magnetic field, which is a combination of regular and random field components, and the standard turbulent magnetic field used in previous correlation analyses. As expected from a neutrino sample such as IceCube-40, consistent with atmospheric neutrinos, we have found no significant correlation signal in all the cases. Therefore, this paper is mainly devoted to the comparison of the effect of the different magnetic field hypotheses on the minimum neutrino source flux strength required for a 5σ discovery and the derived 90% C.L. upper limits. We also incorporate in our comparison the cases of different power law indices α=2.2, α=2.5 for the neutrino point source flux. The differences in the 5σ discovery flux for our magnetic field hypotheses is ∼1%–50%, being the maximum difference with the regular JF12 field and standard turbulent field models, being the standard turbulent higher than the regular one, while the minimum is between the no magnetic field and regular JF12 field. Considering the current flux upper limits, we find that IceCube requires a lifetime ≳5 years to observe neutrino-UHECR correlation signals. Our analysis for different power law indices yielded the same relative behavior between different magnetic field models.
Año de publicación: 2016
We apply the Jansson-Farrar JF12 magnetic field model in the context of point source searches by correlating the Telescope Array ultrahigh energy cosmic ray data and the IceCube-40 neutrino candidates, as well as other magnetic field hypotheses. Our field hypotheses are: no magnetic field, the JF12 field considering only the regular component, the JF12 full magnetic field, which is a combination of regular and random field components, and the standard turbulent magnetic field used in previous correlation analyses. As expected from a neutrino sample such as IceCube-40, consistent with atmospheric neutrinos, we have found no significant correlation signal in all the cases. Therefore, this paper is mainly devoted to the comparison of the effect of the different magnetic field hypotheses on the minimum neutrino source flux strength required for a 5σ discovery and the derived 90% C.L. upper limits. We also incorporate in our comparison the cases of different power law indices α=2.2, α=2.5 for the neutrino point source flux. The differences in the 5σ discovery flux for our magnetic field hypotheses is ∼1%–50%, being the maximum difference with the regular JF12 field and standard turbulent field models, being the standard turbulent higher than the regular one, while the minimum is between the no magnetic field and regular JF12 field. Considering the current flux upper limits, we find that IceCube requires a lifetime ≳5 years to observe neutrino-UHECR correlation signals. Our analysis for different power law indices yielded the same relative behavior between different magnetic field models.
Año de publicación: 2016
LHC forward physics
In early 2013 the LHC forward physics and diffraction working group (WG) was formed, as part of the activities of common interest to the LHC experiments organized by the LHC...
Año de publicación: 2016
In early 2013 the LHC forward physics and diffraction working group (WG) was formed, as part of the activities of common interest to the LHC experiments organized by the LHC...
Año de publicación: 2016
The Minimal 3 + 2 Neutrino Model vs. Higgs Decays
The minimal 3+2 neutrino model is a Type-I seesaw model with two Weyl fermions, singlets under the Standard Model. Apart from light neutrino masses and mixings, this model can be fully described by four additional parameters. In this work, we study the minimal 3+2 neutrino model in scenarios where the singlets have masses at the GeV scale. This can lead to Higgs decays into heavy neutrinos, which could be observable as displaced vertices at the LHC.
Año de publicación: 2016
The minimal 3+2 neutrino model is a Type-I seesaw model with two Weyl fermions, singlets under the Standard Model. Apart from light neutrino masses and mixings, this model can be fully described by four additional parameters. In this work, we study the minimal 3+2 neutrino model in scenarios where the singlets have masses at the GeV scale. This can lead to Higgs decays into heavy neutrinos, which could be observable as displaced vertices at the LHC.
Año de publicación: 2016
Probing the Type I Seesaw mechanism with displaced vertices at the LHC
The observation of Higgs decays into heavy neutrinos would be strong evidence for new physics associated to neutrino masses. In this work we propose a search for such decays within the Type I Seesaw model in the few-GeV mass range via displaced vertices. Using 300 fb−1 of integrated luminosity, at 13 TeV, we explore the region of parameter space where such decays are measurable. We show that, after imposing pseudorapidity cuts, there still exists a region where the number of events is larger than (10). We also find that conventional triggers can greatly limit the sensitivity of our signal, so we display several relevant kinematical distributions which might aid in the optimization of a dedicated trigger selection.
Año de publicación: 2015
The observation of Higgs decays into heavy neutrinos would be strong evidence for new physics associated to neutrino masses. In this work we propose a search for such decays within the Type I Seesaw model in the few-GeV mass range via displaced vertices. Using 300 fb−1 of integrated luminosity, at 13 TeV, we explore the region of parameter space where such decays are measurable. We show that, after imposing pseudorapidity cuts, there still exists a region where the number of events is larger than (10). We also find that conventional triggers can greatly limit the sensitivity of our signal, so we display several relevant kinematical distributions which might aid in the optimization of a dedicated trigger selection.
Año de publicación: 2015
Searching for cavities of various densities in the Earth's crust with a low-energy antineutrino electron beta-beam
We propose searching for deep underground cavities of different densities in the Earth’s crust using a long-baseline ν̄ e disappearance experiment, realized through a low-energy β-beam with highly-enhanced luminosity. We focus on four cases: cavities with densities close to that of water, iron-banded formations, heavier mineral deposits, and regions of abnormal charge accumulation that have been posited to appear prior to the occurrence of an intense earthquake. The sensitivity to identify cavities attains confidence levels (C.L.s) higher than 3σ and 5σ for exposure times of three months and 1.5 years, respectively, and cavity densities below 1 g cm−3 or above 5 g cm−3, with widths greater than 200 km. We reconstruct the cavity density, width, and position, assuming one of them known while keeping the other two free. We obtain large allowed regions that improve as the cavity density differs more from the Earth’s mean density. Furthermore, we demonstrate that the knowledge of the cavity density is important to obtain O(10%) error on the width. Finally, we introduce an observable to quantify the presence of a cavity by changing the orientation of the ν̄ e beam, with which we are able to identify the presence of a cavity at the 2σ to 5σ C.L.
Año de publicación: 2015
We propose searching for deep underground cavities of different densities in the Earth’s crust using a long-baseline ν̄ e disappearance experiment, realized through a low-energy β-beam with highly-enhanced luminosity. We focus on four cases: cavities with densities close to that of water, iron-banded formations, heavier mineral deposits, and regions of abnormal charge accumulation that have been posited to appear prior to the occurrence of an intense earthquake. The sensitivity to identify cavities attains confidence levels (C.L.s) higher than 3σ and 5σ for exposure times of three months and 1.5 years, respectively, and cavity densities below 1 g cm−3 or above 5 g cm−3, with widths greater than 200 km. We reconstruct the cavity density, width, and position, assuming one of them known while keeping the other two free. We obtain large allowed regions that improve as the cavity density differs more from the Earth’s mean density. Furthermore, we demonstrate that the knowledge of the cavity density is important to obtain O(10%) error on the width. Finally, we introduce an observable to quantify the presence of a cavity by changing the orientation of the ν̄ e beam, with which we are able to identify the presence of a cavity at the 2σ to 5σ C.L.
Año de publicación: 2015
SUSY Renormalization Group Effects in Ultra High Energy Neutrinos
We have explored the question of whether the renormalization group running of the neutrino mixing parameters in the Minimal Supersymmetric Standard Model is detectable with ultra-high energy neutrinos from active galactic nuclei (AGN). We use as observables the ratios of neutrino fluxes produced at the AGN, focusing on four different neutrino production models: (Φ0𝜈𝑒+𝜈¯𝑒:Φ0𝜈𝜇+𝜈¯𝜇:Φ0𝜈𝜏+𝜈¯𝜏)=(1:2:0),(0:1:0),(1:0:0), and (1 : 1 : 0). The prospects for observing deviations experimentally are taken into consideration, and we find out that it is necessary to impose a cut-off on the transferred momentum of Q 2 ≥ 107 GeV2. However, this condition, together with the expected low value of the diffuse AGN neutrino flux, yields a negligible event rate at a km-scale C̆erenkov detector such as IceCube.
Año de publicación: 2011
We have explored the question of whether the renormalization group running of the neutrino mixing parameters in the Minimal Supersymmetric Standard Model is detectable with ultra-high energy neutrinos from active galactic nuclei (AGN). We use as observables the ratios of neutrino fluxes produced at the AGN, focusing on four different neutrino production models: (Φ0𝜈𝑒+𝜈¯𝑒:Φ0𝜈𝜇+𝜈¯𝜇:Φ0𝜈𝜏+𝜈¯𝜏)=(1:2:0),(0:1:0),(1:0:0), and (1 : 1 : 0). The prospects for observing deviations experimentally are taken into consideration, and we find out that it is necessary to impose a cut-off on the transferred momentum of Q 2 ≥ 107 GeV2. However, this condition, together with the expected low value of the diffuse AGN neutrino flux, yields a negligible event rate at a km-scale C̆erenkov detector such as IceCube.
Año de publicación: 2011