Isovector Dependence of the EMC Effect December 4, 2016 SRC/EMC 2016 IV EMC 1/9
Flavor-modifying EMC effect in asymmetric nuclei is not well constrained and would represent new information on medium modification Existance of flavor dependence can reinforce intuitive ideas of EMC mechanisms e.g. local densities, nucleon overlap An SRC-EMC connection naturally predicts such an effect Such an isovector EMC effect consistent with SRC is in the right direction as CBT model and NuTeV SRC/EMC 2016 IV EMC 2/9
Experimental Access to Flavor in PDFs Some popular proposals to study flavor dependence of EMC effect Leptonic DIS σ Ratios Parity-Violating DIS Asymmetry ∗ γ ∗ 0 Z 2 γ ∗ Drell-Yan - π ± ,p on A SIDIS - π flavor tagging SRC/EMC 2016 IV EMC 3/9
Competing Methods for Direct Measurement PVDIS offers highest sensitivity and is required for full picture 48 48 µ µ 48 40 a a from CBT, from CBT, Ca x/X Ca x/X =12%, 60 days, 80 =12%, 60 days, 80 A A Ca/ Ca Ratios 1 1 0 0 1 1.15 a CBT E139 Param 1 0.98 naive a 1 CBT 1.1 Our Projections (stat, stat+ pt to pt sys) 48 40 Ca/ Ca Ratio (stat + pt to pt sys) 0.96 Shared sys. uncert Ca 40 Shared systematic 2, 1.05 /F 0.94 Ca 1 48 a 1 2, 0.92 is Norm. F 0.9 0.95 0.88 0.9 0.86 0.85 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 x x bj Riordan, Arrington, Beminiwattha Daniel, Arrington, Fomin, Gaskell EMC 48 Ca/ 40 Ca PVEMC (SoLID) E12-10-008 Hall A, 2024? Hall C, 2018? Statistics 0.7-1.3% 0.8-1.1% Systematics 0.5% 0.7% Normalization 0.4% 1.4% CBT x-dependence 5% 3% CBT sensitivity 5 . 6 σ < 3 σ SRC/EMC 2016 IV EMC 4/9
PVDIS PVDIS proves new flavor combinations → isovector properties ∗ γ ∗ Z 0 A PV ∼ ∼ 100 − 1000 ppm 2 γ ∗ ≈ − G F Q 2 a 1 ( x ) + 1 − (1 − y ) 2 , y = 1 − E ′ � � 1 + (1 − y ) 2 a 3 ( x ) √ E 4 2 πα � C 1 q e q ( q + ¯ � C 2 q e q ( q − ¯ q ) q ) � e 2 � e 2 a 1 ( x ) = 2 , a 3 ( x ) = 2 q ( q + ¯ q ) q ( q + ¯ q ) Effective Weak Couplings 3 sin 2 θ W = − 0 . 19 2 + 2 sin 2 θ W = − 0 . 03 C 1 u = − 1 2 + 4 C 2 u = − 1 3 sin 2 θ W = 0 . 34 2 + 2 sin 2 θ W = 0 . 03 1 2 − 2 1 C 1 d = C 2 d = SRC/EMC 2016 IV EMC 5/9
PVDIS PVDIS proves new flavor combinations → isovector properties ∗ γ ∗ 0 Z A PV ∼ ∼ 100 − 1000 ppm 2 γ ∗ ≈ − G F Q 2 a 1 ( x ) + 1 − (1 − y ) 2 , y = 1 − E ′ � � 1 + (1 − y ) 2 a 3 ( x ) √ E 4 2 πα Symmetric nucleus limit u + A − d + a 1 ≃ 9 5 − 4 sin 2 θ W − 12 A + ... u + A + d + 25 A where u A = u in p and u in n SRC/EMC 2016 IV EMC 5/9
SoLID for PVDIS SoLID offers only real method to obtain necessary precision without new facilities Ability to capitalize on JLab limits of energy and luminosity Experimental configuration practically identical and similarly challenging to approved SoLID PVDIS measurement (70 days) Already deferred twice by PAC - at least want 48 Ca / 40 Ca first SoLID not yet formal project, ∼ $60M, realistically wouldn’t start production until at least 2024 SRC/EMC 2016 IV EMC 6/9
Systematics Many potential nuclear effects come into play as this sector is not presently well constrained Requires measurements from LD 2 and LH 2 for information on size of nuclear effects Charge symmetry violation competing effect will also be explored to better precision Existing free PDFS (recent CJ12) have poor d / u constraint a - No Modification, CJ12 pdf Projected 12 GeV d/u Extractions 1 1.05 1 CJ12 - PDF + nucl uncert. 48 Ca - Minimum Correction 3 3 BigBite H/ He DIS 48 Ca - Maximum Correction CLAS12 BoNuS 1 0.8 40 Ca - Middle Correction CLAS12 BoNuS, relaxed cuts Our Statistical Uncertainty SoLID PVDIS 0.95 0.6 SU(6) d/u 1 -a 0.4 0.9 DSE 0.2 0.85 pQCD BoNuS sys. uncert. Broken SU(6) 0 0.8 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 x x SRC/EMC 2016 IV EMC 7/9
PAC Statements SIDIS (E12-09-004) - Kafidi, Dutta, Gaskell PAC 34 - Deferred (with Regret) Cite “ Whilst this of interest ... needs to understand the SIDIS process more completely” Worried about systematics from hadronization in interpretation PVDIS (Our proposal) PAC 42 - Deferred “novel and well developed proposal” Site boundary radiation limits were a concern (since addressed) Cross section measurement sensitivity wasn’t formally studied PAC 44 - Deferred Again Informally - workshop to organize between efforts and converge theory, radiation effects on the hall, target cost, sensitivity “The PAC finds the proposed physics to be interesting but believes that information from experiment E12-10-008 ( 48 Ca/ 40 Ca) should be available before committing the substantial beam and financial resources necessary for this experiment.” SRC/EMC 2016 IV EMC 8/9
Questions to be Resolved Need community to really make strong statement on needs What is the coherent story between all programs? What are the experiments that must be done? What sensitivity do we demand from them? What other modeling or calculations can be done for predictions? What is constrained with new measurements? What are optimal observables or information extraction from models? (Ratios, slopes, differences, global fits, etc) Explore different interpretation scenarios with results from DIS with 48 Ca / 40 Ca PVDIS 48 Ca (or maybe other far future targets e.g. 9 Be ?) Approved SoLID CSV PVDIS on LD 2 Neutrino, Drell-Yan Data - Existing and future (e.g. COMPASS, DUNE) Inclusive and exclusive SRC with (a)symmetric nuclei Beyond the Standard Model Studies (e.g. LHC, sin 2 θ W , dark matter searches) SRC/EMC 2016 IV EMC 9/9
Questions to be Resolved Need community to really make strong statement on needs What is the coherent story between all programs? What are the experiments that must be done? What sensitivity do we demand from them? QMC EMC Modification Predictions What other modeling or calculations can be done for predictions? What is constrained with new measurements? What are optimal observables or information extraction from models? (Ratios, slopes, differences, global fits, etc) Explore different interpretation scenarios with results from DIS with 48 Ca / 40 Ca PVDIS 48 Ca (or maybe other far future targets e.g. 9 Be ?) Approved SoLID CSV PVDIS on LD 2 Neutrino, Drell-Yan Data - Existing and future (e.g. COMPASS, DUNE) Inclusive and exclusive SRC with (a)symmetric nuclei Beyond the Standard Model Studies (e.g. LHC, sin 2 θ W , dark matter searches) SRC/EMC 2016 IV EMC 9/9
BACKUP SRC/EMC 2016 IV EMC 9/9
Spin-Dependent EMC 50 days 11 GeV polarized e − beam on polarized 7 Li (with other targets for systematics) Approved E12-14-001 CLAS12 at JLab - Brooks, Kuhn 7 Li 7 Li 7 Li Measures double spin asymmetry A ≈ g / F 1 1 � SRC/EMC 2016 IV EMC 9/9
Isovector Dependence? - NuTeV Neutrino scattering (charged current and neutral current) is sensitive to different flavor combinations Pachos-Wolfenstein relation: σ ( ν µ N → ν µ X ) − σ (¯ ν µ N → ¯ ν µ X ) R PW ≡ ν µ N → µ + X ) σ ( ν µ N → µ − X ) − σ (¯ 1 2 − sin 2 θ W = lim → i . s . Asymmetric nuclei (iron) need corrections CSV or IVEMC could play very important role and are not well constrained by data SRC/EMC 2016 IV EMC 9/9
Isovector Dependence? - Partitioned Fits Existing fits to world data show controversy Studies partitioning data between lepton/Drell Yan and ν show significant incompatibilities in nuclear corrections using common PDFs I. Schienbein et al. PRD77 054013 (2008); I. Schienbein et al. PRD80 094004 (2009) SRC/EMC 2016 IV EMC 9/9
Isovector Dependence? - SRC SRC show strong preference to n-p pairs over p-p pairs Also show strong correlation to “plateau” parameter for x > 1 SFs SRC/EMC 2016 IV EMC 9/9
Isovector Dependence? - SRC SRC show strong preference to n-p pairs over p-p pairs Also show strong correlation to “plateau” parameter for x > 1 SFs Preliminary models make predictions of deviations for asymmetric nuclei Arrington, EPJ Web Conf. 113, 01011 (2016) SRC/EMC 2016 IV EMC 8/9
Modeling - CBT Model Cloet et al. make predictions based on mean field calculations which give reasonable reproductions of SFs Explicit isovector terms are included constrained by nuclear physics data such as the symmetry energy Few percent effect in a 2 , larger at larger x 48 48 a a from Cloet-Bentz-Thomas for from Cloet-Bentz-Thomas for Ca Ca 1 1 Z/N = 20 / 28 (calcium-48) 1.05 1 . 2 a CBT 1 naive a 1 . 1 1 1 EMC ratios 2 θ 9/5 - 4 sin W 1 0.95 0 . 9 1 a 0 . 8 F 2 A /F 2 D 0.9 d A /d f 0 . 7 Q 2 = 5 GeV 2 0.85 u A /u f 0 . 6 0 0 . 2 0 . 4 0 . 6 0 . 8 1 0.8 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 x Cloet et al. PRL102 252301 (2009), Cloet et al. PRL109 182301 (2012) SRC/EMC 2016 IV EMC 8/9
Modeling - nPDFs Varying weights in fits between lepton/Drell Yan and ν can show tension between data sets nCTEQ fits show dramatic differences in a similar vein at CBT Few percent effect in a 2 48Ca from nCTEQ 0.96 w=0 0.95 w=1/7 w = inf 0.94 0.93 0.92 -a1 0.91 0.9 0.89 0.88 0.87 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 x SRC/EMC 2016 IV EMC 8/9
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