8 research outputs found
Constraining sleptons at the LHC in a supersymmetric low-scale seesaw scenario
No full textThe discovery of the Higgs boson in the 8 TeV run of the LHC [1, 2] marks one of the
most important milestones in particle physics. Its mass is already known rather precisely:
mh = 125.09 ± 0.21 (stat.) ±0.11 (syst.) GeV [3], and the signal strength of various LHC
searches has been found consistent with the SM predictions. While this completes the
Standard Model (SM) particle-wise, several questions still remain open, for example: (i) Is
it possible to include the SM in a grand unified theory where all gauge forces unify? (ii) Is
there a particle physics explanation of the observed dark matter relic density? (iii) What
causes the hierarchy in the fermion mass spectrum and why are neutrinos so much lighter
than the other fermions? What causes the observed mixing patterns in the fermion sector?
(iv) What stabilizes the Higgs mass at the electroweak scale?
Supersymmetric model address several of these questions and consequently the search for
supersymmetry (SUSY) is among the main priorities of the LHC collaborations. Up to now
no significant sign for physics beyond SM has been found. The combination of the Higgs
discovery with the (yet) unsuccessful searches has led to the introduction of a model class
called ‘natural SUSY’ [4–15]. Here, the basic idea is to give electroweak-scale masses only
to those SUSY particles giving a sizeable contribution to the mass of the Higgs boson, such
that a too large tuning of parameters is avoided. All other particle masses are taken at the
multi-TeV scale. In particular, masses of the order of a few hundred GeV up to about one
TeV are assigned to the higgsinos (the partners of the Higgs bosons), the lightest stop (the
partner of the top-quark) and, if the latter is mainly a left-stop, also to the light sbottom In
addition the gluino and the heavier stop masses should also be close to at most a few TeV.
Neutrino oscillation experiments confirm that at least two neutrinos have a non-zero mass.
The exact mass generation mechanism for these particles is unknown, and both the SM and
the MSSM remain agnostic on this topic. Although many ways to generate neutrino mass
exist, perhaps the most popular one is the seesaw mechanism [16–21]. The main problem
with the usual seesaw mechanisms lies on the difficulty in testing its validity. In general, if
Yukawa couplings are sizeable, the seesaw relations require Majorana neutrino masses to be
very large, such that the new heavy states cannot be produced at colliders. In contrast, if
one requires the masses to be light, then the Yukawas need to be small, making production
cross-sections and decay rates to vanish. A possible way out of this dilemma lies on what
3
is called the inverse seesaw [22], which is based on having specific structures on the mass
matrix (generally motivated by symmetry arguments) to generate small neutrino masses.
This, at the same time, allows Yukawa couplings to be large, and sterile masses to be light.
We consider here a supersymmetric model where neutrino data are explained via a minimal
inverse seesaw scenario where the gauge-singlet neutrinos have masses in the range
O(keV) to O(100 GeV). We explore this with a parametrization built for the standard seesaw,
and go to the limit where the inverse seesaw emerges, such that Yukawas and mixings
become sizeable. Although non-SUSY versions of this scenario can solve the dark matter
and matter-antimatter asymmetry problems [23–25], we shall make no claim on these issues
in our model.
In view of the naturalness arguments, we further assume that the higgsinos have masses of
O(100 GeV), whereas the gaugino masses lie at the multi-TeV scale (see [26] for an example
of such a scenario). In addition, we assume all squarks are heavy enough such that LHC
bounds are avoided, and play no role in the phenomenology within this work1. In contrast
we allow for fairly light sleptons and investigate the extent to which current LHC data can
constrain such scenarios.
This paper is organized as follows: in the next section we present the model. Section
III summarizes the numerical tools used and gives an overview of the LHC analysis used
for these investigations. In Section IV we present our findings for the two generic scenarios
which differ in the nature of the lighest supersymmetric particle (LSP): a Higgsino LSP
and a sneutrino LSP. In Section V we draw our conclusions. Appendices A and B give the
complete formulae for the neutrino and sneutrino masses
Constraining sleptons at the LHC in a supersymmetric low-scale seesaw scenario
No full textThe discovery of the Higgs boson in the 8 TeV run of the LHC [1, 2] marks one of the
most important milestones in particle physics. Its mass is already known rather precisely:
mh = 125.09 ± 0.21 (stat.) ±0.11 (syst.) GeV [3], and the signal strength of various LHC
searches has been found consistent with the SM predictions. While this completes the
Standard Model (SM) particle-wise, several questions still remain open, for example: (i) Is
it possible to include the SM in a grand unified theory where all gauge forces unify? (ii) Is
there a particle physics explanation of the observed dark matter relic density? (iii) What
causes the hierarchy in the fermion mass spectrum and why are neutrinos so much lighter
than the other fermions? What causes the observed mixing patterns in the fermion sector?
(iv) What stabilizes the Higgs mass at the electroweak scale?
Supersymmetric model address several of these questions and consequently the search for
supersymmetry (SUSY) is among the main priorities of the LHC collaborations. Up to now
no significant sign for physics beyond SM has been found. The combination of the Higgs
discovery with the (yet) unsuccessful searches has led to the introduction of a model class
called ‘natural SUSY’ [4–15]. Here, the basic idea is to give electroweak-scale masses only
to those SUSY particles giving a sizeable contribution to the mass of the Higgs boson, such
that a too large tuning of parameters is avoided. All other particle masses are taken at the
multi-TeV scale. In particular, masses of the order of a few hundred GeV up to about one
TeV are assigned to the higgsinos (the partners of the Higgs bosons), the lightest stop (the
partner of the top-quark) and, if the latter is mainly a left-stop, also to the light sbottom In
addition the gluino and the heavier stop masses should also be close to at most a few TeV.
Neutrino oscillation experiments confirm that at least two neutrinos have a non-zero mass.
The exact mass generation mechanism for these particles is unknown, and both the SM and
the MSSM remain agnostic on this topic. Although many ways to generate neutrino mass
exist, perhaps the most popular one is the seesaw mechanism [16–21]. The main problem
with the usual seesaw mechanisms lies on the difficulty in testing its validity. In general, if
Yukawa couplings are sizeable, the seesaw relations require Majorana neutrino masses to be
very large, such that the new heavy states cannot be produced at colliders. In contrast, if
one requires the masses to be light, then the Yukawas need to be small, making production
cross-sections and decay rates to vanish. A possible way out of this dilemma lies on what
3
is called the inverse seesaw [22], which is based on having specific structures on the mass
matrix (generally motivated by symmetry arguments) to generate small neutrino masses.
This, at the same time, allows Yukawa couplings to be large, and sterile masses to be light.
We consider here a supersymmetric model where neutrino data are explained via a minimal
inverse seesaw scenario where the gauge-singlet neutrinos have masses in the range
O(keV) to O(100 GeV). We explore this with a parametrization built for the standard seesaw,
and go to the limit where the inverse seesaw emerges, such that Yukawas and mixings
become sizeable. Although non-SUSY versions of this scenario can solve the dark matter
and matter-antimatter asymmetry problems [23–25], we shall make no claim on these issues
in our model.
In view of the naturalness arguments, we further assume that the higgsinos have masses of
O(100 GeV), whereas the gaugino masses lie at the multi-TeV scale (see [26] for an example
of such a scenario). In addition, we assume all squarks are heavy enough such that LHC
bounds are avoided, and play no role in the phenomenology within this work1. In contrast
we allow for fairly light sleptons and investigate the extent to which current LHC data can
constrain such scenarios.
This paper is organized as follows: in the next section we present the model. Section
III summarizes the numerical tools used and gives an overview of the LHC analysis used
for these investigations. In Section IV we present our findings for the two generic scenarios
which differ in the nature of the lighest supersymmetric particle (LSP): a Higgsino LSP
and a sneutrino LSP. In Section V we draw our conclusions. Appendices A and B give the
complete formulae for the neutrino and sneutrino masses
Mapping the Landscape of Blockchain for Transparent and Sustainable Supply Chains: A Bibliometric and Thematic Analysis
No full textBackground: The increasing complexity of global supply chains has intensified the demand for transparency, traceability, security, and sustainability in logistics and operations. Blockchain technology enables decentralized, immutable frameworks that improve data integrity, automate transactions via smart contracts, and integrate seamlessly with the IoT and AI. Methods: This bibliometric review analyzes 559 peer-reviewed publications retrieved from Scopus and Web of Science using a PRISMA-guided protocol. Data were processed with Bibliometrix and Biblioshiny to examine scientific production, contributing institutions, author countries, collaboration patterns, thematic clusters, and keyword evolution. Results: The analysis reveals a 400% increase in publications after 2020, with China, India, and the USA leading in output but with limited international collaboration. Keyword co-occurrence and thematic mapping reveal dominant topics, including smart contracts, food supply chain traceability, and sustainability, as well as emerging themes such as decentralization, privacy, and the circular economy. Conclusions: The field is marked by interdisciplinary growth, yet it remains thematically and geographically fragmented. This review maps the intellectual structure of blockchain-enabled sustainable supply chains, offering insights for policymakers, developers, and industry leaders and outlining future research avenues centered on global cooperation, platform efficiency, and ethical and regulatory dimensions
Constraining sleptons at the LHC in a supersymmetric low-scale seesaw scenario
No full textAbstract 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
Advancements and Applications of Machine Learning in Detecting Radon Nuclear Tracks from 2001 to 2023: A Bibliometric Analysis
No full textWe present a bibliometric analysis of the advancements in machine learning for detecting radon nuclear tracks, using publications from 2001 to 2023 sourced from Scopus and Web of Science databases. We analyze the growth in research output, particularly highlighting contributions from China and the United States, and identify key themes such as "machine learning", "radon", "neural networks", and emerging methods like "xgboost" and "long short-term memory networks". Our findings underscore the collaborative efforts within the field, as evidenced by the global authorship networks. The research landscape is mapped out, revealing core and peripheral areas of study that define the current state and prospects of radon detection research. The present study encapsulates the evolution of the field and emphasizes the necessity for continued interdisciplinary collaboration to enhance radon risk assessment methods
Application of Statistical Methods for the Characterization of Radon Distribution in Indoor Environments: A Case Study in Lima, Peru
No full textThis study evaluates the effectiveness of advanced statistical and geospatial methods for analyzing radon concentration distributions in indoor environments, using the district of San Martín de Porres, Lima, Peru, as a case study. Radon levels were monitored using LR-115 nuclear track detectors over three distinct measurement periods between 2015 and 2016, with 86 households participating. Detectors were randomly placed in various rooms within each household. Normality tests (Shapiro–Wilk, Anderson–Darling, and Kolmogorov–Smirnov) were applied to assess the fit of radon concentrations to a log-normal distribution. Additionally, analysis of variance (ANOVA) was used to evaluate the influence of environmental and structural factors on radon variability. Non-normally distributed data were normalized using a Box–Cox transformation to improve statistical assumptions, enabling subsequent geostatistical analyses. Geospatial interpolation methods, specifically Inverse Distance Weighting (IDW) and Kriging, were employed to map radon concentrations. The results revealed significant temporal variability in radon concentrations, with geometric means of 146.4 Bq·m−3 , 162.3 Bq·m−3 , and 150.8 Bq·m−3 , respectively, across the three periods. Up to 9.5% of the monitored households recorded radon levels exceeding the safety threshold of 200 Bq·m−3 . Among the interpolatio methods, Kriging provided a more accurate spatial representation of radon concentration variability compared to IDW, allowing for the precise identification of high-risk areas. This study provides a framework for using advanced statistical and geospatial techniques in environmental risk assessment
Assessing Radiological Risks and Natural Radioactivity in Building Materials from Ica, Peru
No full textThe study investigated the radon emission rate and potential radiological hazards of high-uranium-content building materials in The Ica area of Southwestern Peru. We used a creative technique that combined a closed chamber and active monitor, and it was improved by a hermetic sealing method to maintain secular equilibrium well. The results showed radon emission rates as low as below detection limits (BDL) up to 52.3 mBq/kg·h. Our analyses with a 3' x 3' NaI detector found radionuclide concentrations in cement samples by gamma spectrometry. We found a high positive correlation between radium activity concentration and radon exhalation rate. The activity concentrations of 226Ra, 232Th, and 40K differ significantly, with maximum values reaching 60.6, 22.3, and 1074 mBq/kg·h. We consider these results significant for the safety of materials in the Peruvian construction sector. And we also hope that they will provide information to support radiological risk management
Comprehensive Study of Natural Radioactivity in Building Materials: A Case Study in Ica, Peru
No full textThis study evaluates radon exhalation rates and assesses the potential radiological risks of external exposure to primordial radionuclides in building materials employed in the Ica region of Peru, particularly those with high uranium content. The radon exhalation rates are currently measured using a combination of a closed chamber and an active monitor. We proposed a novel method that effectively ensured a hermetic seal for the closed chamber and guaranteed that the efficient maintenance of secular equilibrium. The obtained results ranged from below the detection limit (BDL) to a maximum of 52.3 mBq · kg−1h−1. Gamma spectrometry was employed to measure the concentrations of radionuclides by utilizing a 3′ × 3′ NaI detector. The analysis of cement samples revealed a strong positive correlation between the activity concentration of radium and the radon exhalation rate. The activity concentrations for radionuclides varied, with values ranging from BDL to 60.6 mBq · kg−1h−1 for 226Ra, BDL to 22.3 mBq · kg−1h−1 for 232Th, and BDL to 1074 mBq · kg−1h−1 for 40K. These findings contribute valuable insight to decision-making processes in the Peruvian construction industry, particularly regarding material safety and radiological risk management
