[Hadstruct] [EXTERNAL] Re: Proposed abstracts for Lattice 2021

Thu Apr 29 15:51:02 EDT 2021

Hello All,

Per Savva's suggestion, Christos and I spoke and amended our abstracts and
titles to reflect sequential presentations.
Co-authors for all: Robert, ME, Christos, Kostas, David, Eloy and Savvas

*Christos*
Title: Towards High-Precision Nucleon Parton Distributions via Distillation
- I

Abstract: We compute the unpolarized valence quark parton distribution
function (PDF) from Lattice QCD, using a gauge ensemble of $N_f=2+1$
Wilson-Clover fermions with $m_\pi = 350$ MeV. Promising results from a
second ensemble at the physical pion mass are also presented. We employ the
pseudo-PDF formalism in combination with the distillation method for the
first time, yielding a significantly improved statistical precision of the
computed Ioffe-time distributions (ITDs) and resulting x-dependence over
traditional methods for calculating matrix elements. We compare our
extracted x-dependence of the nucleon valence PDF with phenomenology and
other recent lattice evaluations.

*Colin*

Title: Towards High-Precision Nucleon Parton Distributions via Distillation
- II

Abstract: The pseudo-distribution formalism is one such methodology capable
of illuminating the collinear structure of hadrons from matrix elements of
suitably constructed space-like operators calculated using lattice QCD.
Expounding upon the unpolarized nucleon PDF calculation of the HadStruc
collaboration, the improved statistical quality of the computed Ioffe-time
pseudo-distributions opens the possiblity of rigorously quantifying
systematics inherent to this calculation. A method to simultaneously
extract the PDFs and capture and remove systematic effects is developed.
This bolsters the prospect of a model-independent PDF extraction.
Comparisons are made with contemporary results from the lattice community
and an array of phenomenological determinations.

Comments are appreciated.

Thanks,

Colin

On Thu, Apr 29, 2021 at 2:07 PM Savvas Zafeiropoulos <savvaslz at gmail.com>
wrote:

> Hey Christo and Colin,
>
> Should you arrange for back to back talks? That would be better…And you
> should email the organisers to make sure that one of you is going to do the
> part A and the other the part B….
>
> Best,
> Savvas
>
> On 29 Apr 2021, at 19:58, Christos Kallidonis <kallidoc at jlab.org> wrote:
>
> Hello all,
>
> Here’s my contribution for the Lattice conference. It looks like mine and
> Colin’s abstract have quite an overlap, but we should be able to resolve
> this (perhaps by considering presenting GPDs as well?).
>
> *Co-Authors:* Robert Edwards, Colin Egerer, Kostas Orginos, David
> Richards, Savvas Zafeiropoulos
>
> *Title: *The nucleon valence quark distribution functions from Lattice
> QCD: An exploratory study of distillation in the pseudo-PDF framework
>
> *Abstract:* We compute the unpolarized valence quark parton distribution
> function (PDF) from Lattice QCD, using a gauge ensemble of $N_f=2+1$
> Wilson-Clover fermions with $m_\pi = 350$ MeV. Preliminary results from a
> second ensemble at the physical pion mass are also presented. We employ the
> pseudo-PDF formalism in combination with the distillation method for the
> first time, yielding a significantly improved statistical accuracy of the
> computed Ioffe-time distributions (ITDs) and resulting x-dependence over
> traditional methods for calculating matrix elements. We elaborate on the
> perturbative 1-loop evolution of the ITDs as well as a set of PDF
> parametrization schemes and discuss various systematics. We compare our
> extracted x-dependence of the nucleon valence PDF with phenomenology and
> with other recent Lattice QCD evaluations.
>
>
> Any comments or suggestions are welcome.
> Thanks.
>
> Best,
> Christos
>
>
> On Apr 29, 2021, at 1:17 PM, Nikhil Karthik <nkarthik.work at gmail.com>
> wrote:
>
> Hi all,
>
> Here is the transversity PDF abstract. Please let me know your
> suggestions, if any.
>
> Title:  The transversity PDF of the nucleon using the pseudo-distribution
> approach
>
> Abstract:
> The transversity parton distribution function probes the x-dependent
> difference between quarks with their spins aligned and anti-aligned with
> the transverse polarization of the nucleon. The chiral-odd nature of the
> transversity makes it experimentally harder to extract than unpolarized
> distributions, thereby making the lattice determination very crucial.  In
> this talk, we will present results on the lattice computation of the
> nucleon transversity PDF using the distillation method and by employing the
> pseudo-distribution approach on an ensemble with the lattice spacing
> a=0.094 fm and 358 MeV pion mass.
>
> Thank you.
> Nikhil
>
> On Thu, Apr 29, 2021 at 12:35 PM Colin Egerer <cpegerer at email.wm.edu>
> wrote:
>
>> Hi All,
>>
>> I'll add one more in this list of abstracts. Should I be unable to
>> present during the meeting, I will arrange with Christos on how to best
>> present our findings.
>> As for co-authors, I have: Christos, Kostas, Anatoly, David, Eloy and
>> Savvas.
>>
>> Title:
>> Towards High-Precision Parton Distributions via Distillation
>>
>> Abstract:
>> The pseudo-distribution formalism is one such methodology capable of
>> illuminating the collinear structure of hadrons from matrix elements of
>> suitably constructed space-like operators calculated using lattice QCD.
>> Leveraging the distillation spatial smearing program, we extract the
>> unpolarized isovector valence and plus quark PDFs of the nucleon via a
>> direct 1-loop matching of the computed Ioffe-time pseudo-distribution and
>> PDF parameterizations. The tempering of excited-states and improved volume
>> sampling afforded by distillation lead to high quality Ioffe-time
>> pseudo-distributions and their $\overline{\text{MS}}$ light-cone
>> counterparts. This bolsters confidence in the extracted PDFs, and allows
>> for a rigorous quantitative accounting of lattice systematics. The PDFs we
>> determine are compared with contemporary results from the lattice community
>> and an array of phenomenological determinations.
>>
>>
>> Thanks,
>> Colin
>>
>> On Thu, Apr 29, 2021 at 12:25 PM Raza Sufian <sufian at jlab.org> wrote:
>>
>>> Dear All,
>>>
>>> Below please find my abstract. Since I do not know yet whether matrix
>>> elements of pseudo-PDF or LCS or both can have signal, I do not mention any
>>> formalism and just say Ioffe-time distribution.
>>>
>>> *Title: Towards determining polarized gluon distribution from lattice
>>> QCD*
>>>
>>> *Abstract: We present a calculation of lattice QCD non-local matrix
>>> elements that can be used to determine polarized gluon Ioffe-time
>>> distribution and the corresponding parton distribution function using QCD
>>> short distance factorization. We construct the nucleon interpolation fields
>>> using the distillation technique and flow the gauge fields using the
>>> gradient flow technique. Our calculation is performed on a $32^3 \times
>>> 64$ **isotropic lattice with a pion mass of 358 MeV.*
>>>
>>> Thank you.
>>> -Raza
>>>
>>> On Apr 29, 2021, at 11:27 AM, Wayne Morris <wmorr001 at odu.edu> wrote:
>>>
>>> *Unpolarized and polarized gluon pseudo-distributions at short
>>> distances: Forward case*
>>>
>>> We present the results that are necessary in the ongoing lattice
>>> calculations of the unpolarized and polarized gluon parton distribution
>>> functions (PDFs) within the pseudo-PDF approach. We give a classification
>>> of possible two-gluon correlator functions and identify those that contain
>>> the invariant amplitude determining the gluon PDF in the light-cone $z^2\to
>>> 0$ limit. One-loop calculations have been performed in the coordinate
>>> representation and in an explicitly gauge-invariant form. We made an effort
>>> to separate ultraviolet (UV) and infrared (IR) sources of the $\ln
>>> \left(-z^2\right) $-dependence at short distances $z^2$. The UV terms
>>> cancel in the reduced Ioffe-time distribution (ITD), and we obtain the
>>> matching relation between the reduced ITD and the light-cone ITD. Using a
>>> kernel form, we get a direct connection between lattice data for the
>>> reduced ITD and the normalized gluon PDF.
>>>
>>> On Thu, Apr 29, 2021 at 11:09 AM Md Tanjib Atique Khan <
>>> mkhan01 at email.wm.edu> wrote:
>>>
>>>> Dear all,
>>>>
>>>> Here is my abstract for Lattice21.
>>>>
>>>> Title: Calculation of the Gluon PDF using Pseudo-PDF technique
>>>>
>>>> Abstract:
>>>>
>>>> We present our calculation of the unpolarized gluon parton distribution function (PDF) in the nucleon using Pseudo-PDF technique on a $32^3 \times 64$
>>>> isotropic lattice with a pion mass of 358 MeV. The nucleon interpolating fields are constructed using the distillation method while the sGEVP method is
>>>> used to calculate the gluonic matrix elements. We implement the gradient-flow technique to compute the flowed matrix elements and using the double ratio,
>>>> calculate the flowed reduced Ioffe-time distribution (rITD). We extrapolate the results to the flow-time independent rITD and calculate the light-cone ITD
>>>> in $\overline{MS}$ scheme, at the small z-separation limit, using NLO matching formula. Finally, the gluon PDF is calculated from the light-cone ITD by
>>>> applying appropriate kernel form.
>>>>
>>>> Thanks,
>>>>
>>>> Tanjib
>>>>
>>>>
>>>> On Wed, Apr 28, 2021 at 5:55 PM Savvas Zafeiropoulos <
>>>> savvaslz at gmail.com> wrote:
>>>>
>>>>> Dear All,
>>>>>
>>>>> here is my abstract and title for lattice 2021
>>>>>
>>>>> *Progress on the extraction of parton distributions from Ioffe time
>>>>> distributions*
>>>>>
>>>>> The light-cone definition of Parton Distribution Functions (PDFs) does
>>>>> not allow for a direct ab initio determination employing methods of Lattice
>>>>> QCD simulations that naturally take place in Euclidean spacetime. In this
>>>>> presentation we focus on pseudo-PDFs where the starting point is the equal
>>>>> time hadronic matrix element with the quark and anti-quark fields separated
>>>>> by a finite distance. We focus on Ioffe-time distributions, which are
>>>>> functions of the Ioffe-time ν, and can be understood as the Fourier
>>>>> transforms of parton distribution functions with respect to the momentum
>>>>> fraction variable x. We present lattice results for the case of the nucleon
>>>>> addressing the physical point and continuum extrapolations. We also
>>>>> incorporate our lattice data in the NNPDF framework treating them on the
>>>>> same footing as experimental data and discuss in detail the different
>>>>> sources of systematics in the determination of the non-singlet PDFs.
>>>>>
>>>>> Since I am going to present results from three published papers all
>>>>> the authors of those papers will be contributors for my talk in the indico
>>>>> website.
>>>>> If anyone has a suggestion/correction etc please let me know!
>>>>>
>>>>> Best,
>>>>> Savvas
>>>>>
>>>>> On Wed, Apr 28, 2021 at 3:55 PM Raza Sufian <sufian at jlab.org> wrote:
>>>>>
>>>>>> Dear All,
>>>>>>
>>>>>> Below please find the proposed abstracts for the Lattice 2021
>>>>>> conference. The deadline for abstract submission is on Friday, April 30.
>>>>>> Please try to circulate your abstracts sometime tomorrow for comments.
>>>>>> Please let us know if I forgot to list any other proposed abstract.
>>>>>>
>>>>>> CK: Nucleon valence distribution using distillation
>>>>>>
>>>>>> SZ: Nucleon valence distribution (continuum limit, physical point
>>>>>> extrapolation + NNPDF analysis)
>>>>>>
>>>>>> TK: Unpolarized gluon distribution
>>>>>>
>>>>>> JK: RBC/UKQCD
>>>>>>
>>>>>> NK: Transversity
>>>>>>
>>>>>> RSS: Polarized gluon distribution
>>>>>>
>>>>>> WM: Perturbative matching for …
>>>>>>
>>>>>>
>>>>>> *TBD:*
>>>>>>
>>>>>> Patrick Barry
>>>>>>
>>>>>> CE
>>>>>>
>>>>>> Thank you.
>>>>>> -Raza
>>>>>> _______________________________________________
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