arXiv subjects

R. Dermisek

Publications and source records attributed to R. Dermisek.

17 recordsLinked to original sources

arXiv2025

United States Muon Collider Community White Paper for the European Strategy for Particle Physics Update

This document is being submitted to the 2024-2026 European Strategy for Particle Physics Update (ESPPU) process on behalf of the US Muon Collider community, with its preparation coordinated by the interim US Muon Collider Coordination Group. The US Muon Collider Community comprises a few hundred American scientists. The purpose of the document is to inform ESPPU about the US plans for Muon Collider research and development (R&D), explain how these efforts align with the broader international R&D initiatives, and present the US community vision for the future realization of this transformative project.

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arXiv2025

The Linear Collider Facility (LCF) at CERN

In this paper we outline a proposal for a Linear Collider Facility as the next flagship project for CERN. It offers the opportunity for a timely, cost-effective and staged construction of a new collider that will be able to comprehensively map the Higgs boson's properties, including the Higgs field potential, thanks to a large span in centre-of-mass energies and polarised beams. A comprehensive programme to study the Higgs boson and its closest relatives with high precision requires data at centre-of-mass energies from the Z pole to at least 1 TeV. It should include measurements of the Higgs boson in both major production mechanisms, ee -> ZH and ee -> vvH, precision measurements of gauge boson interactions as well as of the W boson, Higgs boson and top-quark masses, measurement of the top-quark Yukawa coupling through ee ->ttH, measurement of the Higgs boson self-coupling through HH production, and precision measurements of the electroweak couplings of the top quark. In addition, ee collisions offer discovery potential for new particles complementary to HL-LHC.

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arXiv2025

A Linear Collider Vision for the Future of Particle Physics

In this paper we review the physics opportunities at linear $e^+e^-$ colliders with a special focus on high centre-of-mass energies and beam polarisation, take a fresh look at the various accelerator technologies available or under development and, for the first time, discuss how a facility first equipped with a technology mature today could be upgraded with technologies of tomorrow to reach much higher energies and/or luminosities. In addition, we will discuss detectors and alternative collider modes, as well as opportunities for beyond-collider experiments and R\&D facilities as part of a linear collider facility (LCF). The material of this paper will support all plans for $e^+e^-$ linear colliders and additional opportunities they offer, independently of technology choice or proposed site, as well as R\&D for advanced accelerator technologies. This joint perspective on the physics goals, early technologies and upgrade strategies has been developed by the LCVision team based on an initial discussion at LCWS2024 in Tokyo and a follow-up at the LCVision Community Event at CERN in January 2025. It heavily builds on decades of achievements of the global linear collider community, in particular in the context of CLIC and ILC.

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arXiv2023

Muon Collider Forum Report

A multi-TeV muon collider offers a spectacular opportunity in the direct exploration of the energy frontier. Offering a combination of unprecedented energy collisions in a comparatively clean leptonic environment, a high energy muon collider has the unique potential to provide both precision measurements and the highest energy reach in one machine that cannot be paralleled by any currently available technology. The topic generated a lot of excitement in Snowmass meetings and continues to attract a large number of supporters, including many from the early career community. In light of this very strong interest within the US particle physics community, Snowmass Energy, Theory and Accelerator Frontiers created a cross-frontier Muon Collider Forum in November of 2020. The Forum has been meeting on a monthly basis and organized several topical workshops dedicated to physics, accelerator technology, and detector R&D. Findings of the Forum are summarized in this report.

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arXiv2019

Beyond the Standard Model Physics at the HL-LHC and HE-LHC

This is the third out of five chapters of the final report [1] of the Workshop on Physics at HL-LHC, and perspectives on HE-LHC [2]. It is devoted to the study of the potential, in the search for Beyond the Standard Model (BSM) physics, of the High Luminosity (HL) phase of the LHC, defined as $3~\mathrm{ab}^{-1}$ of data taken at a centre-of-mass energy of $14~\mathrm{TeV}$, and of a possible future upgrade, the High Energy (HE) LHC, defined as $15~\mathrm{ab}^{-1}$ of data at a centre-of-mass energy of $27~\mathrm{TeV}$. We consider a large variety of new physics models, both in a simplified model fashion and in a more model-dependent one. A long list of contributions from the theory and experimental (ATLAS, CMS, LHCb) communities have been collected and merged together to give a complete, wide, and consistent view of future prospects for BSM physics at the considered colliders. On top of the usual standard candles, such as supersymmetric simplified models and resonances, considered for the evaluation of future collider potentials, this report contains results on dark matter and dark sectors, long lived particles, leptoquarks, sterile neutrinos, axion-like particles, heavy scalars, vector-like quarks, and more. Particular attention is placed, especially in the study of the HL-LHC prospects, to the detector upgrades, the assessment of the future systematic uncertainties, and new experimental techniques. The general conclusion is that the HL-LHC, on top of allowing to extend the present LHC mass and coupling reach by $20-50\%$ on most new physics scenarios, will also be able to constrain, and potentially discover, new physics that is presently unconstrained. Moreover, compared to the HL-LHC, the reach in most observables will generally more than double at the HE-LHC, which may represent a good candidate future facility for a final test of TeV-scale new physics.

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arXiv2013

Baryon Number Violation

This report, prepared for the Community Planning Study - Snowmass 2013 - summarizes the theoretical motivations and the experimental efforts to search for baryon number violation, focussing on nucleon decay and neutron-antineutron oscillations. Present and future nucleon decay search experiments using large underground detectors, as well as planned neutron-antineutron oscillation search experiments with free neutron beams are highlighted.

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arXiv2012

Trilepton Signatures of Light Charged and CP-odd Higgs Bosons in Top Quark Decays

In singlet extensions of the two Higgs doublet model, a light CP-odd Higgs boson (A) can significantly modify decay modes of the charged Higgs, without necessarily affecting decay modes of the standard model-like Higgs boson. These effects can be sizable even if the doublet component of the light CP-odd Higgs is small, so that constraints from Upsilon decays and direct CP-odd Higgs production do not apply. We study a scenario in which the charged Higgs is produced in top quark decays, t -> H+ b, with dominant H+ -> W A. We focus on the CP-odd Higgs mass range below the bb threshold. We summarize all current experimental constraints and find that, as a result of H+ -> W A dominance, this scenario is not constrained in a large region of tan(beta), mH+, and CP-odd Higgs doublet component. We discuss search strategies based on A -> tau tau, with both taus decaying leptonically, and on the subleading decay mode A -> mu mu. We show that a search for t -> H+ b, H+ -> W A, A -> mu mu in 20 fb^-1 of 8 TeV LHC data can constrain most of the currently allowed parameter space. Existing trilepton searches are not sensitive to this signal due to the adopted isolation criteria.

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arXiv2008

DUSEL Theory White Paper

The NSF has chosen the site for the Deep Underground Science and Engineering Laboratory (DUSEL) to be in Lead, South Dakota. In fact, the state of South Dakota has already stepped up to the plate and contributed its own funding for the proposed lab, see http://www.sanfordlaboratoryathomestake.org/index.html. The final decision by NSF for funding the Initial Suite of Experiments for DUSEL will be made early in 2009. At that time the NSF Science Board must make a decision. Of order 200 experimentalists have already expressed an interest in performing experiments at DUSEL. In order to assess the interest of the theoretical community, the Center for Cosmology and Astro-Particle Physics (CCAPP) at The Ohio State University (OSU) organized a 3-day DUSEL Theory Workshop in Columbus, Ohio from April 4 - 6, 2008. The workshop focused on the scientific case for six proposed experiments for DUSEL: long baseline neutrino oscillations, proton decay, dark matter, astrophysical neutrinos, neutrinoless double beta decay and N-Nbar oscillations. The outcome of this workshop is the DUSEL Theory White paper addressing the scientific case at a level which may be useful in the decision making process for policy makers at the NSF and in the U.S. Congress. In order to assess the physics interest in the DUSEL project we have posted the DUSEL Theory White paper on the following CCAPP link http://ccapp.osu.edu/whitepaper.html . Please read the white paper and, if you are interested, use the link to show your support by co-signing the white paper.

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arXiv2007

SO(10) SUSY GUT for Fermion Masses : Lepton Flavor and CP Violation

We discuss the results of a global $χ^2$ analysis of a simple SO(10) SUSY GUT with $D_3$ family symmetry and low energy R parity. The model describes fermion mass matrices with 14 parameters and gives excellent fits to 20 observable masses and mixing angles in both quark and lepton sectors, giving 6 predictions. Bi-large neutrino mixing is obtained with hierarchical quark and lepton Yukawa matrices; thus avoiding the possibility of large lepton flavor violation. The model naturally predicts small 1-3 neutrino mixing, with $\sin θ_{13} \simeq 0.05 - 0.06$. In this paper we evaluate the predictions for the lepton flavor violating processes, $μ\to e γ$, $τ\to μγ$ and $τ\to e γ$ and also the electric dipole moment of the electron, $d_e$, muon and tau, assuming universal squark and slepton masses, $m_{16}$, and a universal soft SUSY breaking A parameter, $A_0$, at the GUT scale. We find $Br(μ\to e γ)$ is naturally below present bounds, but may be observable by MEG. Similarly, $d_e$ is below present bounds; but is within the range of future experiments. We also give predictions for the light Higgs mass (using FeynHiggs). We find an upper bound given by $m_h \leq 127$ GeV, with an estimated $\pm 3$ GeV theoretical uncertainty. Finally we present predictions for SUSY particle masses in the favored region of parameter space.

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arXiv2006

CP Studies and Non-Standard Higgs Physics

There are many possibilities for new physics beyond the Standard Model that feature non-standard Higgs sectors. These may introduce new sources of CP violation, and there may be mixing between multiple Higgs bosons or other new scalar bosons. Alternatively, the Higgs may be a composite state, or there may even be no Higgs at all. These non-standard Higgs scenarios have important implications for collider physics as well as for cosmology, and understanding their phenomenology is essential for a full comprehension of electroweak symmetry breaking. This report discusses the most relevant theories which go beyond the Standard Model and its minimal, CP-conserving supersymmetric extension: two-Higgs-doublet models and minimal supersymmetric models with CP violation, supersymmetric models with an extra singlet, models with extra gauge groups or Higgs triplets, Little Higgs models, models in extra dimensions, and models with technicolour or other new strong dynamics. For each of these scenarios, this report presents an introduction to the phenomenology, followed by contributions on more detailed theoretical aspects and studies of possible experimental signatures at the LHC and other colliders.

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arXiv2005

Dark Matter And $B_s \to μ^+ μ^-$ With Minimal $SO_{10}$ Soft SUSY Breaking II

We update and extend to larger masses our previous analysis of the MSSM with minimal $SO_{10}$ [MSO$_{10}$SM] soft SUSY breaking boundary conditions. We find a well--defined, narrow region of parameter space which provides the observed relic density of dark matter, in a domain selected to fit precision electroweak data, including top, bottom and tau masses. The model is highly constrained which allows us to make several predictions. We find the light Higgs mass $m_h \leq 121 \pm 3$ GeV and also upper bounds on the mass of the gluino $\mgluino\lsim3.1$ TeV and lightest neutralino $\mchi\lsim450$ GeV. As the CP odd Higgs mass $m_A$ increases, the region of parameter space consistent with WMAP data is forced to larger values of $M_{1/2}$ and smaller values of $m_h$. Hence, we find an upper bound $m_A \lsim 1.3$ TeV. This in turn leads to lower bounds on ${\rm BR}(B_s\to μ^+ μ^-) > 10^{-8}$ (assuming minimal flavor violation) and on the dark matter spin independent detection cross section $\sigsip > 10^{-9}$ pb. Finally, we extend our previous analysis to include WIMP signals in indirect detection and find prospects for WIMP detection generally much less promising than in direct WIMP searches.

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arXiv2003

Dark Matter And $B_s \to μ^+ μ^-$ With Minimal $SO_{10}$ Soft SUSY Breaking

CMSSM boundary conditions are usually used when calculating cosmological dark matter densities. In this paper we calculate the cosmological density of dark matter in the MSSM using minimal $SO_{10}$ soft SUSY breaking boundary conditions. These boundary conditions incorporate several attractive features: they are consistent with $SO_{10}$ Yukawa unification, they result in a "natural" inverted scalar mass hierarchy and they reduce the dimension 5 operator contribution to the proton decay rate. With regards to dark matter, on the other hand, this is to a large extent an unexplored territory with large squark and slepton masses $m_{16}$, large $A_0$ and small $ \{μ, M_{1/2} \} $. We find that in most regions of parameter space the cosmological density of dark matter is considerably less than required by the data. However there is a well--defined, narrow region of parameter space which provides the observed relic density of dark matter, as well as a good fit to precision electroweak data, including top, bottom and tau masses, and acceptable bounds on the branching fraction of $B_s \to μ^+ μ^-$. We present predictions for Higgs and SUSY spectra, the dark matter detection cross section and the branching ratio ${\rm BR}(B_s\to μ^+ μ^-)$ in this region of parameter space.

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arXiv2002

Viable models with non-universal gaugino mediated supersymmetry breaking

Recently, extra dimensional SUSY GUT models have been proposed in which compactification of the extra dimension(s) leads to a breakdown of the gauge symmetry and/or supersymmetry. We examine a particular class of higher-dimensional models exhibiting supersymmetry and SU(5) or SO(10) GUT symmetry. SUSY breaking occurs on a hidden brane, and is communicated to the visible brane via gaugino mediation. Non-universal gaugino masses are developed at the compactification scale as a consequence of a restricted gauge symmetry on the hidden brane. In this case, the compactification scale is at or slightly below the GUT scale. We examine the parameter space of such models where gaugino masses are related due to a Pati-Salam symmetry on the hidden brane. We find limited but significant regions of model parameter space where a viable spectra of SUSY matter is generated. Our results are extended to the more general case of three independent gaugino masses; here we find that large parameter space regions open up for large values of the U(1) gaugino mass M_1. We also find the relic density of neutralinos for these models to be generally below expectations from cosmological observations, thus leaving room for hidden sector states to make up the bulk of cold dark matter. Finally, we evaluate the branching fraction BF(b -> s gamma) and muon anomalous magnetic moment a_μ.

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arXiv2002

Yukawa Unification in SO(10)

In simple SO(10) SUSY GUTs the top, bottom and tau Yukawa couplings unify at the GUT scale. A naive renormalization group analysis, neglecting weak scale threshold corrections, leads to moderate agreement with the low energy data. However it is known that intrinsically large threshold corrections proportional to $\tanβ\sim m_t(M_Z)/m_b(M_Z) \sim 50$ can nullify these $t, b$, $τ$ mass predictions. In this paper we turn the argument around. Instead of predicting fermion masses, we use the constraint of Yukawa unification and the observed values $M_t, m_b(m_b), M_τ$ to constrain SUSY parameter space. We find a narrow region survives for $μ> 0$ with $μ, M_{1/2} << m_{16}$, $A_0 \approx - 1.9 m_{16}$ and $m_{16} > 1200$ \gev. Demanding Yukawa unification thus makes definite predictions for Higgs and sparticle masses. In particular we find a light higgs with mass $m_h^0 = 114 \pm 5 \pm 3$ GeV and a light stop with $(m_{\tilde t_1})_{MIN} \sim 450$ GeV and $m_{\tilde t_1} << m_{\tilde b_1}$. In addition, we find a light chargino and a neutralino LSP. It is also significant that in this region of parameter space the SUSY contribution to the muon anomalous magnetic moment $a_μ^{SUSY} < 16 \times 10^{-10}$.

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arXiv2002

Predictions for Higgs and SUSY spectra from SO(10) Yukawa Unification with mu > 0

We use $t, b, τ$ Yukawa unification to constrain SUSY parameter space. We find a narrow region survives for $μ> 0$ (suggested by \bsgam and the anomalous magnetic moment of the muon) with $A_0 \sim - 1.9 m_{16}$, $m_{10} \sim 1.4 m_{16}$, $m_{16} \sim 1200 -3000$ \gev and $μ, M_{1/2} \sim 100 - 500$ \gev. Demanding Yukawa unification thus makes definite predictions for Higgs and sparticle masses.

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arXiv2001

Yukawa Coupling Unification in SO(10) Supersymmetric Grand Unified Theories

We report on a preferred region of supersymmetric parameter space by t, b, tau Yukawa unification. We find a narrow region survives for mu > 0 (suggested by b --> s gamma and the anomalous magnetic moment of the muon) with A_0 \sim - 2 m_{16}, m_{16} > 1200 GeV, mu, M_{1/2} << m_{16} and tan β\sim 50 \pm 2. Demanding Yukawa unification thus makes definite predictions for Higgs and sparticle masses.

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arXiv2000

Fermion Masses and Neutrino Oscillations in SO(10) SUSY GUT with D_3 x U(1) Family Symmetry

Discrete nonabelian gauge symmetries appear to be the most advantageous candidates for a family symmetry. We present a predictive SO(10) SUSY GUT model with $D_3 \times U(1)$ family symmetry (D_3 is the dihedral group of order 6). The hierarchy in fermion masses is generated by the family symmetry breaking $D_3 \times U(1) \to Z_N \to $ nothing. This model fits the low energy data in the charged fermion sector quite well and naturally provides large angle $ν_μ$-$ν_τ$ mixing describing atmospheric neutrino oscillation data and small angle $ν_e$-$ν_s$ mixing consistent with the small mixing angle MSW solution to the solar neutrino data. In addition, the non-abelian family symmetry D_3 is sufficient to suppress large flavor violations.

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