arXiv subjects

Jose Wudka

Publications and source records attributed to Jose Wudka.

At least 55 records · Page 3Linked to original sources

arXiv2009

Naive solution of the little hierarchy problem and its physical consequences

We argue that adding gauge-singlet real scalars to the Standard Model can both ameliorate the little hierarchy problem and provide a realistic source of Dark Matter. Masses of the scalars should be in the 1-3 TeV range, while the lowest cutoff of the (unspecified) UV completion of the model must be ~> 5 TeV, depending on the Higgs boson mass and the number of singlets present. The scalars couple to the Majorana mass term for right-handed neutrinos implying one massless neutrino. The resulting mixing angles are consistent with the tri-bimaximal mixing scenario.

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arXiv2009

Asymmetric Higgs Sector and Neutrino Mass in an SU(2)_R Model

The asymmetric Higgs sector of one $SU(2)_L \times SU(2)_R$ bidoublet $(ϕ_1^0,ϕ_1^-;ϕ_2^+,ϕ_2^0)$ and one $SU(2)_R$ doublet [but no $SU(2)_L$ doublet] is considered in a nonsupersymmetric left-right extension of the standard model (SM) of particle interactions. The inverse seesaw mechanism for neutrino mass is naturally implemented with the addition of fermion singlets, allowing thereby the possibility of breaking $SU(2)_R$ at the TeV scale. In the limit $v_2 = < ϕ_2^0 > = 0$, the unavoidable flavor-changing neutral Higgs couplings to quarks are studied and shown to be naturally suppressed in $K-\bar{K}$ and $B-\bar{B}$ mixing, as well as in $b \to s γ$. All particles are consistent with having masses less than 1 TeV, and could be observable at the Large Hadron Collider (LHC).

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arXiv2009

Pragmatic approach to the little hierarchy problem: the case for Dark Matter and neutrino physics

We show that the addition of real scalars (gauge singlets) to the Standard Model can both ameliorate the little hierarchy problem and provide realistic Dark Matter candidates. To this end, the coupling of the new scalars to the standard Higgs boson must be relatively strong and their mass should be in the 1-3 TeV range, while the lowest cutoff of the (unspecified) UV completion must be >~ 5 TeV, depending on the Higgs boson mass and the number of singlets present. The existence of the singlets also leads to realistic and surprisingly reach neutrino physics. The resulting light neutrino mass spectrum and mixing angles are consistent with the constraints from the neutrino oscillations.

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arXiv2009

Right-handed neutrino magnetic moments

We discuss the phenomenology of the most general effective Lagrangian, up to operators of dimension 5, build with standard model fields and interactions including right-handed neutrinos. In particular we find there is a dimension 5 electroweak moment operator of right-handed neutrinos, not discussed previously in the literature, which could have interesting phenomenological consequences.

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arXiv2009

Note on the strong CP problem from a 5-dimensional perspective

We consider 5 dimensional gauge theories where the 5th direction is compactified on an interval. The Chern-Simons (CS) terms (favored by naive dimensional analysis) are discussed. A simple scenario with an extra U(1)_X gauge field that couples to SU(3)_{color} through a CS term in the bulk is constructed. The extra component of the Abelian gauge field plays a role of the axion, which in the standard manner solves the strong CP problem easily avoiding most of experimental constraints. This version has an expanded discussion of the phenomenology of the model and various clarifications in the estimation of the operator coefficients in the appendix.

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arXiv2008

Heavy Majorana Neutrinos in the Effective Lagrangian Description: Application to Hadron Colliders

We consider the effects of heavy Majorana neutrinos N with sub-TeV masses. We argue that the mere presence of these particles would be a signal of physics beyond the minimal seesaw mechanism and their interactions are, therefore, best described using an effective Lagrangian. We then consider the complete set of leading effective operators (up to dimension 6) involving the N and Standard Model fields and show that these interactions can be relatively easy to track at high-energy colliders. For example, we find that an exchange of a TeV-scale heavy vector field can yield thousands of characteristic same-sign lepton number violating l^+ l^+ j j events (j=light jet) at the LHC if m_N < 600 GeV, which can also have a distinctive forward-backward asymmetry signal; even the Tevatron has good prospects for this signature if m_N < 300 GeV.

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arXiv2007

Multipartite Dark Matter

Dark matter (comprising a quarter of the Universe) is usually assumed to be due to one and only one weakly interacting particle which is neutral and absolutely stable. We consider the possibility that there are several coexisting dark-matter particles, and explore in some detail the generic case where there are two. We discuss how the second dark-matter particle may relax the severe constraints on the parameter space of the Minimal Supersymmetric Standard Model, as well as other verifiable predictions in both direct and indirect search experiments.

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arXiv2007

Search for New Physics via Single Top Production at the LHC

We consider single-top production as a probe for new physics effects at the Large Hadron Collider (LHC). We argue that for natural theories a small deviation from the Standard Model tree-level couplings in this reaction can be parameterized by 3 higher dimension operators. Precision measurement of these effective couplings in the single-top events, via studying their interference effects with the SM contributions, can discriminate several new physics models. In particular, combining the production rate of three single-top production modes will provide a severe test of the Little Higgs model with T-parity. We find that at the LHC, a 5% accuracy in the measurement of the single-top cross sections would probe the new physics scale up to about $3 {\rm TeV}$.

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arXiv2006

Strategies and obstacles in constructing realistic higher-dimensional models

We discuss several aspects of higher dimensional models that contain bulk gauge and fermion fields only. In particular we argue that non-standard boundary conditions involving charge-conjugate fermion fields offer attractive model building possibilities. We also discuss a no-go theorem for 5-dimensional models which severely limits their phenomenological relevance.

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arXiv2006

Search for new physics via single top production at TeV energy $eγ$ colliders

We study the sensitivity of $ e γ$ colliders to physics beyond the Standard Model, when such interactions are natural and their scale lies below the collider energy. Using the reaction $ e γ\to b t ν$ as a specific example, we show that the deviations from the Standard Model can be parameterized in a model independent way by only 3 numbers. We investigate the sensitivity of several observables to these 3 quantities, using the various collider polarization modes to increase the signal to noise ratio. These results are then translated into the expected sensitivity derived from this reaction to the new physics effects present in several specific models.

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arXiv2006

5-Dimensional Difficulties of Gauge-Higgs Unifications

We consider 5 dimensional gauge theories where the 5th direction is compactified on the orbifold S^1/Z_2, and where the 5th components of the gauge bosons play the role of the Standard Model Higgs boson (gauge-Higgs unification). The gauge symmetry breaking is realized through the appropriate orbifold boundary conditions and through the Hosotani mechanism. We show that for {\em any such theory} the assumption that the low-energy vector-boson spectrum consists of the W^\pm, Z and γonly, is inconsistent with the experimental requirements \sin^2θ_W\simeq 1/4 and ρ\equiv m_W^2/(m_Z^2\cos^2θ_w)=1.

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arXiv2006

New-Physics Search through gamma gamma -> t tbar -> lX/bX

We probe optimal beam polarizations for new-physics search in top-quark and Higgs-boson sectors at Photon Linear Colliders (PLC). Expressing possible non-standard effects generated by SU(2)xU(1) gauge-invariant dimension-6 effective operators as anomalous top and Higgs couplings, we estimate expected statistical sensitivities of these couplings in gamma gamma -> t tbar -> lX/bX, using the optimal-observable method.

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arXiv2005

Light excitations in 5-dimensional gauge theories

We consider general five-dimensional gauge theories compactified on on an orbifold S1/Z2 with all fields propagating in the bulk. We propose a generalized set of boundary conditions and derive the general features of the low energy-spectrum. The results are illustrated with two simple examples.

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arXiv2005

Optimal Beam Polarizations for New-Physics Search through gamma gamma -> t tbar -> lX/bX

We perform an optimal-observable analysis of the final charged-lepton/b-quark momentum distributions in gamma+gamma -> t+tbar -> lX/bX for various beam polarizations in order to study possible anomalous t-tbar-gamma, tbW and gamma-gamma-H couplings, which could be generated by SU(2)xU(1) gauge-invariant dimension-6 effective operators. We find optimal beam polarizations that will minimize the uncertainty in determination of those non-standard couplings. We also compare e+ebar and gamma+gamma colliders from the viewpoint of the anomalous-top-quark-coupling determination.

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arXiv2005

Studying Possible Anomalous Top-Quark Couplings at Photon Colliders

Search for new-physics through possible anomalous t tbar gamma, tbW and gamma gamma H couplings which are generated by SU(2) X U(1) gauge-invariant dimension-6 effective operators is discussed, using energy and angular distributions of final charged-lepton/ b-quark in gamma gamma -> t tbar -> l X / bX for various beam polarizations. Optimal beam polarizations that minimize uncertainty in determination of those non-standard couplings are found performing an optimal-observable analysis.

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arXiv2005

Majorana Fermions and CP Violation from 5-dimensional Theories; a Systematic Approach

Within five-dimensional compactified theories we discuss generalized periodicity and orbifold boundary conditions that allow for mixing between particles and anti-particles after a shift by the size of extra dimensions or after the orbifold reflection. A systematic strategy for constructing 4-dimensional models is presented, in particular we find a general form of the periodicity and orbifold conditions that are allowed by consistency requirements. We formulate general conditions for a presence of massless Kaluza-Klein modes and discuss remaining gauge symmetry of the zero-mode sector. It is shown that if the orbifold twist operation transforms particles into anti-particles then the zero-mode fermions are 4-dimensional Majorana fermions. The possibility of explicit and spontaneous CP violation is discussed. General considerations are illustrated by many Abelian and non-Abelian examples.

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arXiv2004

Optimal-Observable Analysis of Possible New Physics Using the b-quark in gamma gamma -> tt -> bX

We study possible anomalous top-quark couplings generated by SU(2) x U(1) gauge invariant dimension-6 effective operators, using the final b-quark momentum distribution in gamma gamma -> tt -> bX. Taking into account non-standard tt gamma, tbW and gamma gamma H couplings, we perform an optimal-observable analysis in order to estimate the precision for the determination of all relevant non-standard couplings.

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arXiv2004

Probing Anomalous Top-Quark Couplings Induced by Dim.6 Operators at Photon Colliders

Possible anomalous top-quark couplings induced by SU(2) x U(1) gauge-invariant dimension-6 effective operators were studied in the process of t t-bar productions and decays at polarized gamma gamma colliders. Two CP-violating asymmetries, a linear-polarization asymmetry and a circular-polarization asymmetry, were computed including both non-standard [t t-bar gamma] and [gamma gamma H] couplings. An optimal-observable analysis for the process gamma gamma --> t t-bar --> l^{+-} ... was performed in order to estimate the precision for determination of all relevant non-standard couplings, including the anomalous tbW coupling.

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