Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “PARITY”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,711 records · Page 95
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Connecting pseudo-Nambu-Goldstone dark matter with pseudo-Dirac neutrinos in a left-right symmetry model

Stringent constraints from the dark matter (DM) direct detection experiments can be naturally evaded for a pseudo-Nambu-Goldstone boson (pNGB) DM. We propose a realization of pNGB DM in the context of a left-right symmetric model, wherein the neutrinos are pseudo-Dirac in nature. The Dirac mass term for neutrinos arises from two-loop quantum corrections, whereas the Majorana mass terms are generated from Planck-induced corrections. This class of model also provides a parity solution to the strong C P problem without the need for an axion. We show an interesting correlation between the lifetime of the DM and the mass-squared differences between active and sterile neutrinos while maintaining a solution to the strong C P problem. Published by the American Physical Society 2025

Biswas, Sumit (ORCID:0009000561143501)↗
DOE OSTI2025

Noble dark matter: Surprising elusiveness of dark baryons

Dark matter could be a baryonic composite of stronglyc upled constituents transforming under SU⁡(2) 𝐿 . We classify the SU⁡(2) 𝐿 representations of baryons in a class of simple confining dark sectors and find that the lightest state can be a pure singlet or a singlet that mixes with other neutral components of SU⁡(2) 𝐿 representations, which strongly suppresses the dark matter candidate’s interactions with the Standard Model. We focus on models with a confining SU⁡(𝑁 𝑐 ) and heavy dark quarks constituting vectorlike 𝑁 𝑓 -plet of SU⁢(2) 𝐿 . For benchmark 𝑁 𝑐 and 𝑁 𝑓 , we calculate baryon mass spectra, incorporating electroweak gauge boson exchange in the nonrelativistic quark model, and demonstrate that above TeV mass scales, dark matter is dominantly a singlet state. The combination of this singlet nature with the recently discovered ℋ-parity results in an inert state analogous to noble gases, hence we coin the term noble dark matter. Our results can be understood in the nonrelativistic effective theory that treats the dark baryons as elementary states, where we find singlets accompanying triplets, 5-plets, or more exotic representations. This generalization of WIMP-like theories is more difficult to find or rule out than dark matter models that include only a single SU⁡(2) 𝐿 multiplet (such as a wino), motivating new searches in colliders and a reanalysis of direct and indirect detection prospects in astrophysical observations.

dark matter direct detection↗
DOE OSTI2011

Measurement of the Mass and Width of the Ds1(2536)+ Meson

The decay width and mass of the D{sub s1}(2536){sup +} meson are measured via the decay channel D{sub s1}{sup +} {yields} D*{sup +} K{sub S}{sup 0} using 385 fb{sup -1} of data recorded with the BABAR detector in the vicinity of the {Upsilon}(4S) resonance at the PEP-II asymmetric-energy electron-positron collider. The result for the decay width is {Gamma}(D{sub s1}{sup +}) = 0.92 {+-} 0.03 (stat.) {+-} 0.04 (syst.)MeV. For the mass, a value of m(D{sub s1}{sup +}) = 2535.08 {+-} 0.01 (stat.) {+-} 0.15 (syst.)MeV/c{sup 2} is obtained. The mass difference between the D{sub s1}{sup +} and the D*{sup +} is measured to be m(D{sub s1}{sup +})-m(D*{sup +}) = 524.83 {+-} 0.01 (stat.) {+-} 0.04 (syst.)MeV/c{sup 2}, representing a significant improvement compared to the current world average. The unnatural spin-parity assignment for the D{sub s1}{sup +} meson is confirmed.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Collider signatures of the SO(5)xU(1) gauge-Higgs unification

Collider signatures of the SO(5)xU(1) gauge-Higgs unification model in the Randall-Sundrum warped space are explored. Gauge couplings of quarks and leptons receive small corrections from the fifth dimension whose effects are tested by the precision data. It is found that the forward-backward asymmetries in e{sup +}e{sup -} collisions on the Z pole are well explained in a wide range of the warp factor z{sub L}, but the model is consistent with the branching fractions of Z decay only for large z{sub L} > or approx. 10{sup 15}. Kaluza-Klein (KK) spectra of gauge bosons, quarks, and leptons as well as gauge and Higgs couplings of low-lying KK excited states are determined. Right-handed quarks and leptons have larger couplings to the KK gauge bosons than left-handed ones. Production rates of Higgs bosons and KK states at the Tevatron, LHC, and International Linear Collider are evaluated. The first KK Z has a mass 1130 GeV with a width 422 GeV for z{sub L}=10{sup 15}. The current limit on the Z' production at the Tevatron and LHC indicates z{sub L}>10{sup 15}. A large effect of parity violation appears in the difference between the rapidity distributions of e{sup +} and e{sup -} in the decay of the first KK Z. The first KK gauge bosons decay into light and heavy quarks evenly.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Directly Measuring the Tensor Structure of the Scalar Coupling to Gauge Bosons

Kinematic distributions in the decays of the newly discovered resonance to four leptons can provide a direct measurement of the tensor structure of the particle's couplings to gauge bosons. Even if the particle is shown to be a parity even scalar, measuring this tensor structure is a necessary step in determining if this particle is responsible for giving mass to the Z. We consider a Standard Model like coupling as well as coupling via a dimension five operator to either ZZ or Z\gamma. We show that using full kinematic information from each event allows discrimination between renormalizable and higher dimensional coupling to ZZ at the 95% confidence level with O(50) signal events, and coupling to Z\gamma can be distinguished with as few as 20 signal events. This shows that these measurements can be useful even with this year's LHC data.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Three pseudoscalar meson production in e+e- annihilation

We study, at leading order in the large number of colours expansion and within the Resonance Chiral Theory framework, the odd-intrinsic-parity $e^+ e^- \rightarrow \pi^+ \pi^- (\pi^0 , \eta)$ cross-sections in the energy regime populated by hadron resonances, namely $9 \, m_{\pi}^2 \lsim E \lsim 2 \, \mbox{GeV}$. In addition we implement our results in the Monte Carlo generator PHOKHARA 7.0 and we simulate hadron production through the radiative return method.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Phenomenology of Dirac Neutralino Dark Matter

In supersymmetric models with an unbroken R-symmetry (rather than only R-parity), the neutralinos are Dirac fermions rather than Majorana. In this article, we discuss the phenomenology of neutralino dark matter in such models, including the calculation of the thermal relic abundance, and constraints and prospects for direct and indirect searches. Due to the large elastic scattering cross sections with nuclei predicted in R-symmetric models, we are forced to consider a neutralino that is predominantly bino, with very little higgsino mixing. We find a large region of parameter space in which bino-like Dirac neutralinos with masses between 10 and 380 GeV can annihilate through slepton exchange to provide a thermal relic abundance in agreement with the observed cosmological density, without relying on coannihilations or resonant annihilations. The signatures for the indirect detection of Dirac neutralinos are very different than predicted in the Majorana case, with annihilations proceeding dominately to $\tau^+ \tau^-$, $\mu^+ \mu^-$ and $e^+ e^-$ final states, without the standard chirality suppression. And unlike Majorana dark matter candidates, Dirac neutralinos experience spin-independent scattering with nuclei through vector couplings (via $Z$ and squark exchange), leading to potentially large rates at direct detection experiments. These and other characteristics make Dirac neutralinos potentially interesting within the context of recent direct and indirect detection anomalies. We also discuss the case in which the introduction of a small Majorana mass term breaks the $R$-symmetry, splitting the Dirac neutralino into a pair of nearly degenerate Majorana states.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Measurement of the C P violation parameters in B 0 → π + π - decays

We present a measurement of the charge-parity ( C P ) violating parameters in B 0 → π + π - decays. The results are obtained from the final data sample containing 772 × 10 6 B B ¯ pairs collected at the Υ ( 4 S ) resonance with the Belle detector at the KEKB asymmetric-energy e + e - collider. We obtain the C P violation parameters A C P ( B 0 → π + π - ) = + 0.33 ± 0.06 ( stat ) ± 0.03 ( syst ) , S C P ( B 0 → π + π - ) = - 0.64 ± 0.08 ( stat ) ± 0.03 ( syst ) , where A C P and S C P represent the direct and mixing-induced C P asymmetries in B 0 → π + π - decays, respectively. Using an isospin analysis including results from other Belle measurements, we find 23.8 ° < Φ 2 < 66.8 ° is disfavored at the 1 σ level, where Φ 2 is one of the three interior angles of the Cabibbo-Kobayashi-Maskawa unitarity triangle related to B u , d decays.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Boosted di-boson from a mixed heavy stop

The lighter mass eigenstate ($\widetilde{t}_1$) of the two top squarks, the scalar superpartners of the top quark, is extremely difficult to discover if it is almost degenerate with the lightest neutralino ($\widetilde{\chi}_1^0$), the lightest and stable supersymmetric particle in the R-parity conserving supersymmetry. The current experimental bound on $\widetilde{t}_1$ mass in this scenario stands only around 200 GeV. For such a light $\widetilde{t}_1$, the heavier top squark ($\widetilde{t}_2$) can also be around the TeV scale. Moreover, the high value of the higgs ($h$) mass prefers the left and right handed top squarks to be highly mixed allowing the possibility of a considerable branching ratio for $\widetilde{t}_2 \to \widetilde{t}_1 h$ and $\widetilde{t}_2 \to \widetilde{t}_1 Z$. In this paper, we explore the above possibility together with the pair production of $\widetilde{t}_2$ $\widetilde{t}_2^*$ giving rise to the spectacular di-boson + missing transverse energy final state. For an approximately 1 TeV $\widetilde{t}_2$ and a few hundred GeV $\widetilde{t}_1$ the final state particles can be moderately boosted which encourages us to propose a novel search strategy employing the jet substructure technique to tag the boosted $h$ and $Z$. The reconstruction of the $h$ and $Z$ momenta also allows us to construct the stransverse mass $M_{T2}$ providing an additional efficient handle to fight the backgrounds. We show that a 4--5$\sigma$ signal can be observed at the 14 TeV LHC for $\sim$ 1 TeV $\widetilde{t}_2$ with 100 fb$^{-1}$ integrated luminosity.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Measurement of branching fractions and C P violation parameters in B → ω K decays with first evidence of C P violation in B 0 → ω K s 0

In this article, we present a measurement of the branching fractions and charge-parity-( C P -)violating parameters in B → ω K decays. The results are obtained from the final data sample containing 772 × 10 6 B B ¯ pairs collected at the Υ ( 4 S ) resonance with the Belle detector at the KEKB asymmetric-energy e + e - collider. We obtain the branching fractions B ( B 0 → ω K 0 ) = ( 4.5 ± 0.4 ( stat ) ± 0.3 ( syst ) ) × 10 - 6 , B ( B + → ω K + ) = ( 6.8 ± 0.4 ( stat ) ± 0.4 ( syst ) ) × 10 - 6 which are in agreement with their respective current world averages. For the C P -violating parameters, we obtain A ω K S 0 = - 0.36 ± 0.19 ( stat ) ± 0.05 ( syst ) , S ω K S 0 = + 0.91 ± 0.32 ( stat ) ± 0.05 ( syst ) , A ω K + = - 0.03 ± 0.04 ( stat ) ± 0.01 ( syst ) , where A and S represent the direct and mixing-induced C P asymmetry, respectively. We find no evidence of C P violation in the decay channel B + → ω K + ; however, we obtain the first evidence of C P violation in the B 0 → ω K S 0 decay channel at the level of 3.1 standard deviations.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Split Dirac Supersymmetry: An Ultraviolet Completion of Higgsino Dark Matter

Motivated by the observation that the Higgs quartic coupling runs to zero at an intermediate scale, we propose a new framework for models of split supersymmetry, in which gauginos acquire intermediate scale Dirac masses of $\sim 10^{8-11}$ GeV. Scalar masses arise from one-loop finite contributions as well as direct gravity-mediated contributions. Like split supersymmetry, one Higgs doublet is fine-tuned to be light. The scale at which the Dirac gauginos are introduced to make the Higgs quartic zero is the same as is necessary for gauge coupling unification. Thus, gauge coupling unification persists (nontrivially, due to adjoint multiplets), though with a somewhat higher unification scale $\gtrsim 10^{17}$ GeV. The $\mu$-term is naturally at the weak scale, and provides an opportunity for experimental verification. We present two manifestations of Split Dirac Supersymmetry. In the "Pure Dirac" model, the lightest Higgsino must decay through R-parity violating couplings, leading to an array of interesting signals in colliders. In the "Hypercharge Impure" model, the bino acquires a Majorana mass that is one-loop suppressed compared with the Dirac gluino and wino. This leads to weak scale Higgsino dark matter whose overall mass scale, as well as the mass splitting between the neutral components, is naturally generated from the same UV dynamics. We outline the challenges to discovering pseudo-Dirac Higgsino dark matter in collider and dark matter detection experiments.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Chiral electric separation effect in the quark-gluon plasma

In this paper we introduce and compute a new transport coefficient for the quark-gluon plasma (QGP) at very high temperature. This new coefficient σ χe , the CESE (Chiral Electric Separation Effect) conductivity, quantifies the amount of axial current J A that is generated in response to an externally applied electric field eE: J A =σ χe (eE). Starting with a rather general argument in the kinetic theory framework, we show how a characteristic structure σ χe ∝μμ5 emerges, which also indicates the CESE as an anomalous transport effect occurring only in a parity-odd environment with nonzero axial charge density μ5 ≠ 0. Using the Hard-Thermal-Loop framework, the CESE conductivity for the QGP is found to be σ χe = (#)TT rf Q e Q A /g⁴ln(1/g) μμ5/T² to the leading-log accuracy with the numerical constant (#) depending on favor content, e.g., (#)=14.5163 for u, d light flavors.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Deconstructed transverse mass variables

Traditional searches for R-parity conserving natural supersymmetry (SUSY) require large transverse mass and missing energy cuts to separate the signal from large backgrounds. SUSY models with compressed spectra inherently produce signal events with small amounts of missing energy that are hard to explore. We use this difficulty to motivate the construction of "deconstructed" transverse mass variables which are designed preserve information on both the norm and direction of the missing momentum. Here, we demonstrate the effectiveness of these variables in searches for the pair production of supersymmetric top-quark partners which subsequently decay into a final state with an isolated lepton, jets and missing energy. We show that the use of deconstructed transverse mass variables extends the accessible compressed spectra parameter space beyond the region probed by traditional methods. The parameter space can further be expanded to neutralino masses that are larger than the difference between the stop and top masses. In addition, we also discuss how these variables allow for novel searches of single stop production, in order to directly probe unconstrained stealth stops in the small stop-and neutralino-mass regime. We also demonstrate the utility of these variables for generic gluino and stop searches in all-hadronic final states. Overall, we demonstrate that deconstructed transverse variables are essential to any search wanting to maximize signal separation from the background when the signal has undetected particles in the final state.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

High-precision calculation of the strange nucleon electromagnetic form factors

We report a direct lattice QCD calculation of the strange nucleon electromagnetic form factors G s E and G s M in the kinematic range 0 ≤ Q 2 ≤ 1.2GeV 2 . For the first time, both G s E and G s M are shown to be nonzero with high significance. This work uses closer-to-physical lattice parameters than previous calculations, and achieves an unprecented statistical precision by implementing a recently proposed variance reduction technique called hierarchical probing . We perform model-independent fits of the form factor shapes using the z-expansion and determine the strange electric and magnetic radii and magnetic moment. As a result, we compare our results to parity-violating electron-proton scattering data and to other theoretical studies.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Missing energy and the measurement of the CP-violating phase in neutrino oscillations

In the next generation of long-baseline neutrino oscillation experiments aiming to determine the charge-parity-violating phase δ CP in the appearance channel, fine-grained time-projection chambers are expected to play an important role. In this study, we analyze an influence of realistic detector capabilities on the δ CP sensitivity for a setup similar to that of the Deep Underground Neutrino Experiment. We find that the effect of the missing energy carried out by undetected particles is sizable. Although the reconstructed neutrino energy can be corrected for the missing energy, the accuracy of such procedure has to exceed 20%, to avoid a sizable bias in the extracted δ CP value.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗