اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدThe Diphoton $q_T$ spectrum at N$^3$LL$^prime$+NNLO
71
0
0.0
(
0
)
تأليف
Tobias Neumann
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
We present a $q_T$-resummed calculation of diphoton production at order N$^3$LL$^prime$+NNLO. To reach the primed level of accuracy we have implemented the recently published three-loop $mathcal{O}(alpha_s^3)$ virtual corrections in the $qbar{q}$ channel and the three-loop transverse momentum dependent beam functions and combined them with the existing infrastructure of CuTe-MCFM, a code performing resummation at order N$^3$LL. While the primed predictions are parametrically not more accurate, one typically observes that they are the dominant effect of the next order. We include in both the $qbar{q}$ and loop-induced $gg$ channel the hard contributions consistently together at order $alpha_s^3$ and find that the resummed $qbar{q}$ channel without matching stabilizes indeed. Due to large matching corrections and large contributions and uncertainties from the $gg$ channel, the overall improvements are small though. We furthermore study the effect of hybrid-cone photon isolation and hard-scale choice on our fully matched results to describe the ATLAS 8 TeV data and find that the hybrid-cone isolation destroys agreement at small $q_T$.
قيم البحث
اقرأ أيضاً
We present a framework for $q_T$ resummation at N$^3$LL+NNLO accuracy for arbitrary color-singlet processes based on a factorization theorem in SCET. Our implementation CuTe-MCFM is fully differential in the Born kinematics and matches to large-$q_T$
fixed-order predictions at relative order $alpha_s^2$. It provides an efficient way to estimate uncertainties from fixed-order truncation, resummation, and parton distribution functions. In addition to $W^pm$, $Z$ and $H$ production, also the diboson processes $gammagamma,Zgamma,ZH$ and $W^pm H$ are available, including decays. We discuss and exemplify the framework with several direct comparisons to experimental measurements as well as inclusive benchmark results. In particular, we present novel results for $gammagamma$ and $Zgamma$ at N$^3$LL+NNLO and discuss in detail the power corrections induced by photon isolation requirements.
We present accurate QCD predictions for the transverse momentum pT spectrum of electroweak gauge bosons at the LHC for 13 TeV collisions, based on a consistent combination of a NNLO calculation at large pT and N3LL resummation in the small pT limit.
The inclusion of higher order corrections leads to substantial changes in the shape of the differential distributions, and the residual perturbative uncertainties are reduced to the few percent level across the whole transverse momentum spectrum. We examine the ratio of pT distributions in charged- and neutral-current Drell-Yan production, and study different prescriptions for the estimate of perturbative uncertainties that rely on different degrees of correlation between these processes. We observe an excellent stability of the ratios with respect to the perturbative order, indicating a strong correlation between the corresponding QCD corrections.
We consider Drell-Yan production $ppto V^* X to L X$ at small $q_T ll Q$. Experimental measurements require fiducial cuts on the leptonic state $L$, which introduce enhanced, linear power corrections in $q_T/Q$. We show that they can be unambiguously
predicted from factorization, and resummed to the same order as the leading-power contribution. We thus obtain predictions for the fiducial $q_T$ spectrum to N3LL and next-to-leading-power in $q_T/Q$. Matching to full NNLO ($alpha_s^2$), we find that the linear power corrections are indeed the dominant ones, and the remaining fixed-order corrections become almost negligible below $q_T lesssim 40$ GeV. We also discuss the implications for more complicated observables, and provide predictions for the fiducial $phi^*$ spectrum at N3LL+NNLO. We find excellent agreement with ATLAS and CMS measurements of $q_T$ and $phi^*$. We also consider the $p_T^ell$ spectrum. We show that it develops leptonic power corrections in $q_T/(Q - 2p_T^ell)$, which diverge near the Jacobian peak $p_T^ell sim Q/2$ and must be kept to all powers to obtain a meaningful result there. Doing so, we obtain for the first time an analytically resummed result for the $p_T^ell$ spectrum around the Jacobian peak at N3LL+NNLO. Our method is based on performing a complete tensor decomposition for hadronic and leptonic tensors. In practice this is equivalent to often-used recoil prescriptions, for which our results now provide rigorous, formal justification. Our tensor decomposition yields nine Lorentz-scalar hadronic structure functions, which directly map onto the commonly used angular coefficients, but also holds for arbitrary leptonic final states. In particular, for suitably defined Born-projected leptons it still yields a LO-like angular decomposition even when including QED final-state radiation. We also discuss the application to $q_T$ subtractions.
We present the analytic formula for the Energy-Energy Correlation (EEC) in electron-positron annihilation computed in perturbative QCD to next-to-next-to-next-to-leading order (N$^3$LO) in the back-to-back limit. In particular, we consider the EEC ar
ising from the annihilation of an electron-positron pair into a virtual photon as well as a Higgs boson and their subsequent inclusive decay into hadrons. Our computation is based on a factorization theorem of the EEC formulated within Soft-Collinear Effective Theory (SCET) for the back-to-back limit. We obtain the last missing ingredient for our computation - the jet function - from a recent calculation of the transverse-momentum dependent fragmentation function (TMDFF) at N$^3$LO. We combine the newly obtained N$^3$LO jet function with the well known hard and soft function to predict the EEC in the back-to-back limit. The leading transcendental contribution of our analytic formula agrees with previously obtained results in $mathcal{N} = 4$ supersymmetric Yang-Mills theory. We obtain the $N=2$ Mellin moment of the bulk region of the EEC using momentum sum rules. Finally, we obtain the first resummation of the EEC in the back-to-back limit at N$^3$LL$^prime$ accuracy, resulting in a factor of $sim 4$ reduction of uncertainties in the peak region compared to N$^3$LL predictions.
We present the resummed predictions for inclusive cross-section for Drell-Yan (DY) production as well as onshell $Z,W^pm$ productions at next-to-next-to-next-to leading logarithmic (N$^{3}$LL) accuracy. Using the standard techniques, we derive the $N
$-dependent coefficients in the Mellin-$N$ space as well as the $N$-independent constants and match the resummed result through the minimal prescription matching procedure with that of existing next-to next-to leading order (NNLO). In addition to the standard $ln N$ exponentiation, we study the numerical impacts of exponentiating $N$-independent part of the soft function and the complete $bar{g}_0$ that appears in the resummed predictions in $N$ space. All the analytical pieces needed in these different approaches are extracted from the soft-virtual part of the inclusive cross section known to next-to-next-to-next-to leading order (N$^3$LO). We perform a detailed analysis on the scale and parton distribution function (PDF) variations and present predictions for the 13 TeV LHC for the neutral Drell-Yan process as well as onshell charged and neutral vector boson productions.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
