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DOE OSTI2025

Systematic uncertainties from higher-twist corrections in DIS at large x

We investigate the systematic uncertainties and potential biases arising from the inclusion of large- x corrections to proton and deuteron deep inelastic scattering (DIS) data in global quantum chromodynamics (QCD) analyses. Using the CTEQ-JLab framework, we examine various approaches to implementing higher-twist corrections in nucleon structure functions and off-shell PDF modifications in deuteron targets. We analyze how these components interact and influence the determination of the d -quark PDF and the neutron structure function at large x . We find that it is very important to consider isospin-dependent higher-twist corrections in order to minimize implementation biases in the extracted quantities. Published by the American Physical Society 2025

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Observation of D → K ¯ 1 ( 1270 ) μ + ν μ and test of lepton flavor universality with D → K ¯ 1 ( 1270 ) ℓ + ν ℓ

By analyzing 7.93 fb − 1 of e + e − collision data collected at the center-of-mass energy of 3.773 GeV with the BESIII detector operated at the BEPCII collider, we report the observation of the semimuonic decays of D + → K ¯ 1 ( 1270 ) 0 μ + ν μ and D 0 → K 1 ( 1270 ) − μ + ν μ with statistical significances of 12.5 σ and 6.0 σ , respectively. Their decay branching fractions are determined to be B [ D + → K ¯ 1 ( 1270 ) 0 μ + ν μ ] = ( 2.36 ± 0.2 0 − 0.27 + 0.18 ± 0.48 ) × 10 − 3 and B [ D 0 → K 1 ( 1270 ) − μ + ν μ ] = ( 0.78 ± 0.1 1 − 0.09 + 0.05 ± 0.15 ) × 10 − 3 , where the first and second uncertainties are statistical and systematic, respectively, and the third originates from the input branching fraction of K ¯ 1 ( 1270 ) 0 → K − π + π 0 or K 1 ( 1270 ) − → K − π + π − . Combining our branching fractions with the previous measurements of B [ D + → K ¯ 1 ( 1270 ) 0 e + ν e ] and B [ D 0 → K 1 ( 1270 ) − e + ν e ] , we determine the branching fraction ratios to be B [ D + → K ¯ 1 ( 1270 ) 0 μ + ν μ ] / B [ D + → K ¯ 1 ( 1270 ) 0 e + ν e ] = 1.03 ± 0.14 − 0.15 + 0.11 and B [ D 0 → K 1 ( 1270 ) − μ + ν μ ] / B [ D 0 → K 1 ( 1270 ) − e + ν e ] = 0.74 ± 0.13 − 0.13 + 0.08 . Using the branching fractions measured in this work and the world-average lifetimes of the D + and D 0 mesons, we determine the semimuonic partial decay width ratio to be Γ [ D + → K ¯ 1 ( 1270 ) 0 μ + ν μ ] / Γ [ D 0 → K 1 ( 1270 ) − μ + ν μ ] = 1.22 ± 0.10 − 0.09 + 0.06 , which is consistent with unity as predicted by isospin conservation. Published by the American Physical Society 2025

Ablikim, M.↗
DOE OSTI2011

Early LHC phenomenology of Yukawa-bound heavy QQ mesons

Current limits from the LHC on fourth generation quarks are already at the unitarity bound of 500 GeV or so. If they exist, the strong Yukawa couplings are turning nonperturbative, and may form bound states. We study the domain of m{sub b'} and m{sub t'} in the range of 500 to 700 GeV, where we expect binding energies are mainly of Yukawa origin, with QCD subdominant. To be consistent with electroweak precision tests, the t' and b' quarks have to be nearly degenerate, exhibiting a new 'isospin'. Comparing relativistic expansion with a relativistic bound state approach, we find the most interesting is the production of a color octet, isosinglet vector meson (a 'gluon-prime') via qq-bar{yields}{omega}{sub 8}. Leading decay modes are {pi}{sub 8}{sup {+-}}W{sup {+-}}, {pi}{sub 8}{sup 0}Z{sup 0}, and constituent quark decay, with qq and tt-bar' and bb' subdominant. The color octet, isovector pseudoscalar {pi}{sub 8} meson decays via constituent quark decay, or to Wg. These decay rates are parameterized by the decay constant, the binding energy and mass differences, and V{sub tb'}. For small V{sub t'b}, one could have a spectacular signal of WWg, where a soft W accompanies a very massive Wg pair. In general, however, one has high multiplicity signals with b, W, and t jet substructures that are not so different from the t't-bar' and b'b-bar' search.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Study of B̄→X u lν̄ decays in BB̄ events tagged by a fully reconstructed B-meson decay and determination of |V ub |

We report measurements of partial branching fractions for inclusive charmless semileptonic B decays B¯¯¯→X u lν¯ and the determination of the Cabibbo–Kobayashi–Maskawa (CKM) matrix element |V ub |. The analysis is based on a sample of 467×10⁶ Υ(4S)→BB¯¯¯ decays recorded with the BABAR detector at the PEP-II e⁺e⁻ storage rings. We select events in which the decay of one of the B mesons is fully reconstructed and an electron or a muon signals the semileptonic decay of the other B meson. We measure partial branching fractions ΔB in several restricted regions of phase space and determine the CKM element |V ub | based on different QCD predictions. For decays with a charged lepton momentum p * l >1.0 GeV in the B meson rest frame, we obtain ΔB=(1.80±0.13stat±0.15sys±0.02theo)×10⁻³ from a fit to the two-dimensional M X -q² distribution. Here, M X refers to the invariant mass of the final state hadron X and q² is the invariant mass squared of the charged lepton and neutrino. From this measurement we extract |V ub |=(4.33±0.24 exp ±0.15 theo )×10⁻³ as the arithmetic average of four results obtained from four different QCD predictions of the partial rate. We separately determine partial branching fractions for B¯¯¯0 and B⁻ decays and derive a limit on the isospin breaking in B¯¯¯→X u lν¯ decays.

Lees, J. P.↗
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 OSTI2014

Measurements of the masses and widths of the Σ c ( 2455 ) 0 / + + and Σ c ( 2520 ) 0 / + + baryons

Here, we highlight measurements of the masses and decay widths of the baryonic states Σ c ( 2455 ) 0 / + + and Σ c ( 2520 ) 0 / + + using a data sample corresponding to an integrated luminosity of 711 fb - 1 collected with the Belle detector at the KEKB e + e - asymmetric-energy collider operating at the Υ ( 4 S ) resonance. We report the mass differences with respect to the Λ c + baryon M ( Σ c ( 2455 ) 0 ) - M ( Λ c + ) = 167.29 ± 0.01 ± 0.02 MeV / c 2 , M ( Σ c ( 2455 ) + + ) - M ( Λ c + ) = 167.51 ± 0.01 ± 0.02 MeV / c 2 , M ( Σ c ( 2520 ) 0 ) - M ( Λ c + ) = 231.98 ± 0.11 ± 0.04 MeV / c 2 , M ( Σ c ( 2520 ) + + ) - M ( Λ c + ) = 231.99 ± 0.10 ± 0.02 MeV / c 2 , and the decay widths Γ ( Σ c ( 2455 ) 0 ) = 1.76 ± 0.0 4 - 0.21 + 0.09 MeV / c 2 , Γ ( Σ c ( 2455 ) + + ) = 1.84 ± 0.0 4 - 0.20 + 0.07 MeV / c 2 , Γ ( Σ c ( 2520 ) 0 ) = 15.41 ± 0.4 1 - 0.32 + 0.20 MeV / c 2 , Γ ( Σ c ( 2520 ) + + ) = 14.77 ± 0.2 5 - 0.30 + 0.18 MeV / c 2 , where the first uncertainties are statistical and the second are systematic. The isospin mass splittings are measured to be M ( Σ c ( 2455 ) + + ) - M ( Σ c ( 2455 ) 0 ) = 0.22 ± 0.01 ± 0.01 MeV / c 2 and M ( Σ c ( 2520 ) + + ) - M ( Σ c ( 2520 ) 0 ) = 0.01 ± 0.15 ± 0.03 MeV / c 2 . These results are the most precise to date.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Comprehensive amplitude analysis of γ γ → π + π - , π 0 π 0 and K ¯ K below 1.5 GeV

In this paper we perform an amplitude analysis of essentially all published pion and kaon pair production data from two photon collisions below 1.5 GeV. This includes all the high statistics results from Belle, as well as older data from Mark II at SLAC, CELLO at DESY, Crystal Ball at SLAC. The purpose of this analysis is to provide as close to a model-independent determination of the γγ to meson pair amplitudes as possible. Having data with limited angular coverage, typically |cosθ| < 0.6-0.8, and no polarization information for reactions in which spin is an essential complication, the determination of the underlying amplitudes might appear an intractable problem. However, imposing the basic constraints required by analyticity, unitarity, and crossing-symmetry makes up for the experimentally missing information. Above 1.5 GeV multi-meson production channels become important and we have too little information to resolve the amplitudes. Nevertheless, below 1.5 GeV the two photon production of hadron pairs serves as a paradigm for the application of S-matrix techniques. Final state interactions among the meson pairs is critical to this analysis. To fix these, we include the latest ππ → ππ, K⁻K scattering amplitudes given by dispersive analyses, supplemented in the K⁻K threshold region by the recent precision Dalitz plot analysis from BaBar. With these hadronic amplitudes built into unitarity, we can constrain the overall description of γγ → ππ and K⁻K datasets, both integrated and differential cross-sections, including the high statistics charged and neutral pion data from Belle. A region of solutions is found for the γγ → ππ partial waves with both isospin 0 and 2. Since this analysis invokes coupled hadronic channels, even the relatively poor integrated cross-section data on γγ → K⁻K narrows the patch of solutions to essentially a single form. For this we present the complete partial wave amplitudes, show how well they fit all the available data, and give the two photon couplings of scalar and tensor resonances that appear.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Resonances in coupled πK, ηK scattering from lattice QCD

Coupled-channel πK and ηK scattering amplitudes are determined by studying the finite-volume energy spectra obtained from dynamical lattice QCD calculations. Using a large basis of interpolating operators, including both those resembling a qq-bar construction and those resembling a pair of mesons with relative momentum, a reliable excited-state spectrum can be obtained. Working at mπ = 391 MeV, we find a gradual increase in the JP = 0+ πK phase-shift which may be identified with a broad scalar resonance that couples strongly to πK and weakly to ηK. The low-energy behavior of this amplitude suggests a virtual bound-state that may be related to the κ resonance. A bound state with JP = 1- is found very close to the πK threshold energy, whose coupling to the πK channel is compatible with that of the experimental K*(892). Evidence is found for a narrow resonance in JP = 2+. Isospin–3/2 πK scattering is also studied and non-resonant phase-shifts spanning the whole elastic scattering region are obtained.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Charged mediators in dark matter scattering with nuclei and the strangeness content of nucleons

We consider a scenario, within the framework of the MSSM, in which dark matter is bino-like and dark matter-nucleon spin-independent scattering occurs via the exchange of light squarks which exhibit left-right mixing. We show that direct detection experiments such as LUX and SuperCDMS will be sensitive to a wide class of such models through spin-independent scattering. Moreover, these models exhibit properties, such as isospin violation, that are not typically observed for the MSSM LSP if scattering occurs primarily through Higgs exchange. The dominant nuclear physics uncertainty is the quark content of the nucleon, particularly the strangeness content

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2015

Coupled π π , K K ¯ scattering in P -wave and the ρ resonance from lattice QCD

In this study, we determine elastic and coupled-channel amplitudes for isospin-1 meson-meson scattering in $P$-wave, by calculating correlation functions using lattice QCD with light quark masses such that $m_\pi = 236$ MeV in a cubic volume of $\sim (4 \,\mathrm{fm})^3$. Variational analyses of large matrices of correlation functions computed using operator constructions resembling $\pi\pi$, $K\overline{K}$ and $q\bar{q}$, in several moving frames and several lattice irreducible representations, leads to discrete energy spectra from which scattering amplitudes are extracted. In the elastic $\pi\pi$ scattering region we obtain a detailed energy-dependence for the phase-shift, corresponding to a $\rho$ resonance, and we extend the analysis into the coupled-channel $K\overline{K}$ region for the first time, finding a small coupling between the channels.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Study of B 0 → ρ + ρ – decays and implications for the CKM angle Φ 2

We present a measurement of the branching fraction and the longitudinal polarization fraction of B 0 → ρ + ρ – decays, as well as the time-dependent CP violating parameters in decays into longitudinally polarized ρ + ρ – pairs with Belle’s final data set of 772 × 10 6 BB¯ pairs, at the Υ(4S) resonance, collected at the asymmetric-energy e + e – collider KEKB. We obtain B(B 0 → ρ + ρ – ) = (28.3 ± 1.5(stat) ± 1.5(syst)) × 10 –6 , f L = 0.988 ± 0.012(stat) ± 0.023(syst), A CP = 0.00 ± 0.10(stat) ± 0.06(syst), S CP = –0.13 ± 0.15(stat) ± 0.05(syst). As a result, we perform an isospin analysis to constrain the Cabibbo-Kobayashi-Maskawa angle Φ 2 and obtain two solutions with Φ 2 = (93.7 ± 10.6)°, being most compatible with other Standard-Model based fits to the data.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Low energy constants of S U ( 2 ) partially quenched chiral perturbation theory from N f = 2 + 1 domain wall QCD

Here, we have performed fits of the pseudoscalar masses and decay constants, from a variety of the RBC-UKQCD Collaboration’s domain wall fermion ensembles, to SU(2) partially quenched chiral perturbation theory at next-to-leading order (NLO) and next-to-next-to-leading order (NNLO). We report values for 9 NLO and 8 linearly independent combinations of NNLO partially quenched low-energy constants, which we compare to other lattice and phenomenological determinations. We discuss the size of successive terms in the chiral expansion and use our large set of low-energy constants to make predictions for mass splittings due to QCD isospin-breaking effects and the S-wave ππ scattering lengths. Lastly, we conclude that, for the range of pseudoscalar masses explored in this work, 115 MeV≲mPS≲430 MeV, the NNLO SU(2) expansion is quite robust and can fit lattice data with percent-scale accuracy.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

An a 0 resonance in strongly coupled π η , K K ¯ scattering from lattice QCD

Here, we present the first calculation of coupled-channel meson-meson scattering in the isospin $=1$, $G$-parity negative sector, with channels $\pi \eta$, $K\overline{K}$ and $\pi \eta'$, in a first-principles approach to QCD. From the discrete spectrum of eigenstates in three volumes extracted from lattice QCD correlation functions we determine the energy dependence of the $S$-matrix, and find that the $S$-wave features a prominent cusp-like structure in $\pi \eta \to \pi \eta$ close to $K\overline{K}$ threshold coupled with a rapid turn on of amplitudes leading to the $K\overline{K}$ final-state. This behavior is traced to an $a_0(980)$-like resonance, strongly coupled to both $\pi \eta$ and $K\overline{K}$, which is identified with a pole in the complex energy plane, appearing on only a single unphysical Riemann sheet. Consideration of $D$-wave scattering suggests a narrow tensor resonance at higher energy.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Pascalutsa-Vanderhaeghen light-by-light sum rule from photon-photon collisions

Light-by-light scattering sumrules based on general field theory principles relate cross-sections with different helicities. In this paper the simplest sumrule is tested for the $I=0$ and $2$ channels for \lq\lq real'' photon-photon collisions. Important contributions come from the long-lived pseudoscalar mesons and from di-meson intermediate states. The latest Amplitude Analysis of $\gamma\gamma\to\pi\pi, \overline{K}K$ allows this contribution to be evaluated. Furthermore, we find that other multi-meson contributions up to 2.5~GeV are required to satisfy the sumrules. While data on three and four pion cross-sections exist, there is no information about their isospin and helicity decomposition. Nevertheless, we show the measured cross-sections are sufficiently large to ensure the sumrules for the helicity differences are likely fulfilled.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Chiral extrapolations of the ρ ( 770 ) meson in N f = 2 + 1 lattice QCD simulations

Recent $N_f=2+1$ lattice data for meson-meson scattering in $p$-wave and isospin $I=1$ are analyzed using a unitarized model inspired by Chiral Perturbation Theory in the inverse-amplitude formulation for two and three flavors. We perform chiral extrapolations that postdict phase shifts extracted from experiment quite well. Additionally, the low-energy constants are compared to the ones from a recent analysis of $N_f=2$ lattice QCD simulations to check for the consistency of the hadronic model used here. Some inconsistencies are detected in the fits to $N_f=2+1$ data, in contrast to the previous analysis of $N_f=2$ data.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Observation of the helicity-selection-rule suppressed decay of the χ c 2 charmonium state

The decays of χ c 2 → K + K - π 0 , K S K ± π ∓ , and π + π - π 0 are studied with the ψ ( 3686 ) data samples collected with the Beijing Spectrometer (BESIII). For the first time, the branching fractions of χ c 2 → K*$\bar{K}$ , χ c 2 → $a_2^±$(1320)π ∓ /$a_2^0$(1320)π 0 , and χ c 2 → ρ( 770 ) ± π ∓ are measured. Here, K*$\bar{K}$ denotes both K* ± K ∓ and its isospin-conjugated process K* 0 $\bar{K}$ 0 +c.c., and K* denotes the resonances K*(892), $K_2^*$(1430), and $K_3^*$(1780). The observations indicate a strong violation of the helicity selection rule in χ c 2 decays into vector and pseudoscalar meson pairs. The measured branching fractions of χ c 2 → K*(892)$\bar{K}$ are more than ten times larger than the upper limit of χ c 2 → ρ ( 770 ) ± π ∓ , which is so far the first direct observation of a significant U -spin symmetry breaking effect in charmonium decays.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗