Mon·Mar 4, 2019Monday·March 4, 2019

1. 01*

   Equation of State for Cosmological Matter at and beyond QCD and Electroweak Eras

   Abdel Nasser Tawfik (Nile U., ECTP & WLCAPP, Cairo)🇪🇬 · Igor Mishustin (Frankfurt U., FIAS & Kurchatov Inst., Moscow)🇩🇪

   Various thermodynamic quantities for baryon-free matter are calculated by combining the most reliable non-perturbative and perturbative calculations, especially the most recent ones including as many quark flavors as possible. We extend these calculations by including other degrees of freedom (dof), such as photons, neutrinos, leptons, electroweak particles, and Higgs bosons, that allows us to consider the temperatures up to the TeV-scale. The calculations show that similar to QCD, the EW phase transition is also a crossover. We have found that while the equation of state for the hadronic matter is linear, $p/\rho \simeq 0.2$, the one for higher temperatures is rather complex; it exhibits two crossover-type phase transitions, corresponding to strong and EW matter. At even larger energy densities, the deduced EoS becomes linear again and close to ideal gas. The combined equation of state can be used for modeling the expansion of the Universe from very early times and through the EW and QCD era.

   hep-phhep-latJ.Phys.G(2019)·15 citations
2. 02*

   General Spin Analysis from Angular Correlations in Two-Body Decays

   Seong Youl Choi🇰🇷 · Jae Hoon Jeong🇰🇷 · Ji Ho Song🇰🇷

   Determining the spin of any new particle and measuring its couplings to other particles and/or itself are crucial in reconstructing the structure of any quantum field theory containing the particle. A general helicity formalism is employed to describe the polarization of the particle $Y$ in a two-body decay $X_2\to Y{X}_1$ with polarized $X_2$ for the purpose of diagnosing the dynamical properties of three involved particles and for determining their spins altogether. We perform a general and comprehensive analytic analysis with our special focus on grasping fully how to connect the decay helicity amplitudes and decay distributions in the $X_2$ rest frame and those in a laboratory frame with $X_2$ moving with a non-zero velocity through Wick helicity rotation on helicity states and amplitudes. This theoretical framework is demonstrated in a detailed illustrative manner with the Standard Model (SM) processes, the sequential process $e^{-}{e}^{+}\to Z\to {\tau }^{-}{\tau }^{+}$ followed by ${\tau }^{-}\to {\rho }^{-}{\nu }_{\tau }\to ({\pi }^{-}{\pi }^0){\nu }_{\tau }$ and the sequential process $e^{-}{e}^{+}\to t\bar{t}$ followed by $t\to W^{+}b\to ({\ell }^{+}{\nu }_{\ell })b$, and one non-standard decay process of a new vectorlike heavy top quark, $T\to Zt$, followed by $Z\to {\ell }^{-}{\ell }^{+}$. All the useful formulas directly applicable to any combinations of spins and any types of couplings in the two-body decay $X_2\to Y{X}_1$ followed by suitable $Y$ two-body decays processes are collected and described in detail.

   hep-phhep-exEur.Phys.J.Plus(2020)·6 citations
3. 03*

   NLO QCD corrections to exclusive electroproduction of quarkonium

   Zi-Qiang Chen🇨🇳 · Cong-Feng Qiao🇨🇳

   The process of exclusive electroproduction of vector quarkonium (EEQ), $ep\to epV$, is per se an interesting topic in studies of quarkonium production mechanism, QCD description of diffractive interaction and nucleon structure. We investigate this process in the framework of nonrelativistic QCD and QCD collinear factorization at the next-to-leading order QCD accuracy. The perturbative convergence behavior is discussed in a large range of photon virtuality $Q^2$. The $J/\psi$ large-$Q^2$ electroproduction data at HERA can be well explained, and the ${\rm Y}$ differential production rate is predicted. The uncertainties in theoretical predictions with radiative corrections are greatly reduced. Notice the EEQ process is extremely sensitive to the gluon distribution in nucleon, the generalized parton distribution, our results will constraint the gluon density with high precision while confronting to the future experimental data. For the sake of comparing convenience, the analytic expressions are provided.

   hep-phPLB(2019)·23 citations
4. 04*

   The energy-momentum tensor of spin-1 hadrons: formalism

   Wim Cosyn🇧🇪 · Sabrina Cotogno🇫🇷 · Adam Freese🇺🇸 · Cédric Lorcé🇫🇷

   We provide the complete decomposition of the local gauge-invariant energy-momentum tensor for spin-1 hadrons, including non-conserved terms for the individual parton flavors and antisymmetric contributions originating from intrinsic spin. We state sum rules for the gravitational form factors appearing in this decomposition and provide relations for the mass decomposition, work balance, total and orbital angular momentum, mass radius, and inertia tensor. Generalizing earlier work, we derive relations between the total and orbital angular momentum and the Mellin moments of twist-2 and 3 generalized parton distributions, accessible in hard exclusive processes with spin-1 targets. Throughout the work, we comment on the unique features in these relations originating from the spin-1 nature of the hadron, being absent in the lower spin cases.

   hep-phnucl-exnucl-thEPJC(2019)·66 citations
5. 05*

   Angular analysis of the rare decay ${\Lambda }_b\to \Lambda (1520)(\to NK){\ell }^{+}{\ell }^{-}$

   Sébastien Descotes-Genon🇫🇷 · Martín Novoa-Brunet🇫🇷

   We study the differential decay rate for the rare decay ${\Lambda }_b\to \Lambda (1520)(\to NK){\ell }^{+}{\ell }^{-}$ where $\ell$ is a light lepton, as this decay mode can provide new and complementary constraints on the Wilson coefficients in $b\to s{\ell }^{+}{\ell }^{-}$ transitions compared to other modes. We provide a determination of the complete angular distribution, assuming unpolarised ${\Lambda }_b$ baryons and neglecting the lepton mass. The resulting angular observables are expressed in terms of helicity amplitudes involving hadronic form factors within the Standard Model and New physics models with chirality-flipped operators. We study these observables at low and large $\Lambda$ recoils, using effective theories to determine relations among the hadronic form factors involved. As there is currently no determination of the form factors available from lattice simulations or light-cone sum rules, we perform a first illustration of the sensitivity of some observables to New Physics contributions using hadronic inputs from quark models.

   hep-phhep-exJHEP(2019)·54 citations
6. 06*

   ALP inflation and Big Bang on Earth

   Fuminobu Takahashi🇯🇵 · Wen Yin🇰🇷

   We study a hilltop inflation model where an axion-like particle (ALP) plays the role of the inflaton. We find that, for a broad class of potentials, the decay constant and the mass at the potential minimum satisfy the relation, $m_{\varphi }\sim 10^{-6}f$, to explain the CMB normalization. The ALP is necessarily coupled to the standard model particles for successful reheating. The ALP with the above relation can be searched at beam dump experiments, e.g., the SHiP experiment, if the inflation scale is sufficiently low. In this case, the ALP decays through the interactions that led to the reheating of the Universe. In other words, the Big Bang may be probed at ground-based experiments.

   hep-phastro-ph.COgr-qcJHEP(2019)·60 citations
7. 07*

   Proposal for gravitational direct detection of dark matter

   Daniel Carney🇺🇸 · Sohitri Ghosh🇺🇸 · Gordan Krnjaic🇺🇸 · Jacob M. Taylor🇺🇸

   The only coupling dark matter is guaranteed to have with the standard model is through gravity. Here we propose a concept for direct dark matter detection using only this gravitational coupling. We suggest that an array of quantum-limited mechanical impulse sensors may be capable of detecting the correlated gravitational force created by a passing dark matter particle. We consider the effects of irreducible noise from couplings of the sensors to the environment and noise due to the quantum measurement process. We show that the signal from Planck-scale dark matter is in principle detectable using a large number of gram-scale sensors in a meter-scale array with sufficiently low quantum noise, and discuss some experimental challenges en route to achieving this target.

   hep-phastro-ph.IMhep-exquant-phPRD(2020)·94 citations
8. 08*

   Experimental Observation of Acceleration-Induced Thermality

   Morgan H. Lynch🇮🇱 · Eliahu Cohen🇮🇱 · Yaron Hadad🇺🇸 · Ido Kaminer🇮🇱

   We examine the radiation emitted by high energy positrons channeled into silicon crystal samples. The positrons are modeled as semiclassical vector currents coupled to an Unruh-DeWitt detector to incorporate any local change in the energy of the positron. In the subsequent accelerated QED analysis, we discover a Larmor formula and power spectrum that are both thermalized by the acceleration. Thus, these systems explicitly exhibit thermalization of the detector energy gap at the celebrated Fulling-Davies-Unruh (FDU) temperature. Our derived power spectrum, with a nonzero energy gap, is then shown to have an excellent statistical agreement with high energy channeling experiments and also provides a method to directly measure the FDU temperature. We also investigate the Rindler horizon dynamics and confirm that the Bekenstein-Hawking area-entropy law is satisfied in these experiments. As such, we present the evidence for the first observation of acceleration-induced thermality in a non-analogue system.

   ↳ gr-qchep-phhep-thPRD(2021)·49 citations
9. 09*

   Comment on Daya Bay's definition and use of Delta m^2_ee

   Stephen J. Parke🇺🇸 · Renata Zukanovich Funchal🇧🇷

   We comment on Daya Bay's latest definition of the effective Delta m^2 for short baseline reactor electron antineutrino disappearance experiments used in arXiv:1809.02261 (Phys. Rev. Lett. 121, no. 24, 241805 (2018))

   ↳ hep-exhep-ph3 citations
10. 10*

    Masses of ground-state mesons and baryons, including those with heavy quarks

    Pei-Lin Yin🇨🇳 · Chen Chen🇧🇷 · Gastao Krein🇧🇷 · Craig D. Roberts🇺🇸 · Jorge Segovia🇪🇸 · Shu-Sheng Xu🇨🇳

    Using a confining, symmetry-preserving regularisation of a vector$\times$vector contact interaction, we compute the spectra of ground-state pseudoscalar and vector $(f\bar{g})$ mesons, scalar and axial-vector $(fg)$ diquarks, and $J^P=1/2^{+},3/2^{+}$ $(fgh)$ baryons, where $f,g,h\in \{u,d,s,c,b\}$. The diquark correlations are essentially dynamical and play a key role in formulating and solving the three-valence-quark baryon problems. The baryon spectrum obtained from this largely-algebraic approach reproduces the 22 known experimental masses with an accuracy of $2.9(2.4)$%. It also possesses the richness of states typical of constituent-quark models, predicting many heavy-quark baryons not yet observed. This study indicates that diquark correlations are an important component of all baryons; and owing to the dynamical character of the diquarks, it is typically the lightest allowed diquark correlation which defines the most important component of a baryon's Faddeev amplitude.

    ↳ nucl-thhep-lathep-phPRD(2019)·112 citations
11. 11*

    Finite Temperature Landau Gauge Lattice Quark Propagator

    Orlando Oliveira🇵🇹 · Paulo J. Silva🇵🇹

    The quark propagator at finite temperature is investigated using quenched gauge configurations. The propagator form factors are investigated for temperatures above and below the gluon deconfinement temperature $T_c$ and for the various Matsubara frequencies. Significant differences between the functional behaviour below and above $T_c$ are observed both for the quark wave function and the running quark mass. The results for the running quark mass indicate a strong link between gluon dynamics, the mechanism for chiral symmetry breaking and the deconfinement mechanism. For temperatures above $T_c$ and for low momenta, our results support also a description of quarks as free quasi-particles.

    ↳ hep-lathep-phEPJC(2019)·8 citations
12. 12*

    Lattice QCD Method To Study Parton To Hadron Fragmentation Function

    Gouranga C Nayak

    In the literature it is assumed that the parton to hadron fragmentation function cannot be studied by using the lattice QCD method because of the sum over the (unobserved) outgoing hadronic states. However, in this paper we find that since the hadron formation from the partons can be studied by using the lattice QCD method, the parton to hadron fragmentation function can be studied by using the lattice QCD method by using the LSZ reduction formula for the partonic processes.

    ↳ physics.gen-phhep-ph6 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.