Fri·Oct 23, 2020Friday·October 23, 2020

1. 01*

   Dispersive $\pi K\to \pi K$ and $\pi \pi \to K\bar{K}$ amplitudes from scattering data, threshold parameters and the lightest strange resonance $\kappa$ or $K_0^{\ast }(700)$

   J.R. Peláez🇪🇸 · A. Rodas🇺🇸

   We discuss the simultaneous dispersive analyses of $\pi K\to \pi K$ and $\pi \pi \to K\bar{K}$ scattering data and the $\kappa /K_0^{\ast }(700)$ resonance. The unprecedented statistics of present and future Hadron Experiments, modern Lattice QCD calculations, and the wealth of new states and decays, require such precise and model-independent analyses to describe final state interactions. We review the existing and often conflicting data and explain in detail the derivation of the relevant dispersion relations, maximizing their applicability range. Next, we review and extend the caveats on some data, showing their inconsistency with dispersion relations. Our main result is the derivation and compilation of precise amplitude parameterizations constrained by several $\pi K\to \pi K$ and $\pi \pi \to K\bar{K}$ dispersion relations. These constrained parameterizations are easily implementable and provide the rigor and accuracy needed for modern experimental and phenomenological Hadron Physics. As applications, after reviewing their status and interest, we will provide new precise threshold and subthreshold parameters and review our dispersive determination of the controversial $\kappa /K_0^{\ast }(700)$ resonance and other light-strange resonances.

   hep-phhep-exhep-latnucl-thPhys.Rept.(2022)·99 citations
2. 02*

   Sub-femtometer scale color charge fluctuations in a proton made of three quarks and a gluon

   Adrian Dumitru🇺🇸 · Risto Paatelainen🇫🇮

   The light-front wave function of a proton composed of three quarks and a perturbative gluon is computed. This is then used to derive expressions for the color charge density correlator $⟨{\rho }^a({\vec{q}}_1){\rho }^b({\vec{q}}_2)⟩$ at $\mathcal{O}(g^4)$ due to the emission of a gluon by one of the quarks in light-cone gauge. The correlator exhibits the soft and collinear singularities. Albeit, we employ exact gluon emission and absorption vertices, and hence the gluon is not required to carry very small light-cone momentum, or to be collinear to the emitting quark. We verify that the correlator satisfies the Ward identity and that it is independent of the renormalization scale, i.e. that ultraviolet divergences cancel. Our expressions provide x-dependent initial conditions for Balitsky-Kovchegov evolution of the C-even part of the dipole scattering matrix to higher energies. That is, we determine the first non-trivial moment of the color charge fluctuations which act as sources for soft color fields in the proton with wavelengths greater than approximately $1/x\sim 10-100$.

   hep-phPRD(2021)·44 citations
3. 03*

   Searching signature of neutrino-nucleus coherent scattering with Mössbauer Spectroscopy

   C Marques🇧🇷 · G S Dias🇧🇷 · H S Chavez · S B Duarte🇧🇷

   The Mössbauer spectroscopy is presented as an alternative experimental technique to be pursued in the detec-tion of Coherent Elastic{\nu}-Nucleus Scattering (CENNS). The neutrino transferred energy in the neutrino-nucleusinteraction causes a perturbation at the nuclear levels which are responsible for gamma radiation in Mössbauerresonance. The main characteristic of Mössbauer spectroscopy is the recoil less condition imposed on the nucleiimposed by quantum restrictions of the crystalline array potential. Coherent neutrino scattering is expected tooccurs low energy regime of the beam, typically below 30 MeV, at higher neutrino energies small incoherencecomponent appears in the scattering[30] as disturbances within the internal nuclear degrees of freedom. Inthis work we have shown that using anti neutrino reactor beam, with the accuracy of Mössbauer technique itspossible to obtain a measurable signature of the Coherent neutrino Scattering.

   hep-phnucl-ex0 citations
4. 04*

   Aspects of model dependence of eta'-eta complex treated by going beyond the isospin limit

   Davor Horvatic🇭🇷 · Dubravko Klabucar🇭🇷 · Dalibor Kekez🇭🇷

   Exploring the extent of model dependence, we study effects of certain Ansaetze for the T-dependence of the correction term in the QCD topological susceptibility. The one producing unwanted effects on results at T > 0 in the eta'-eta complex in the usual limit of isospin symmetry, is largely cured from its peculiar behavior and brought into agreement with the other, when breaking of isospin symmetry is allowed and the realistic quark mass ratio m_u/m_d = 0.50 is adopted.

   hep-phnucl-thEPJA(2020)·1 citation
5. 05*

   New methods to reconstruct $X_{\max }$ and the energy of gamma-ray air showers with high accuracy in large wide-field observatories

   R. Conceição🇵🇹 · L. Peres🇧🇷 · M. Pimenta🇵🇹 · B. Tomé🇵🇹

   Novel methods to reconstruct the slant depth of the maximum of the longitudinal profile (\Xmax) of high-energy showers initiated by gamma-rays as well as their energy ($E_0$) are presented. The methods were developed for gamma rays with energies ranging from a few hundred GeV to $\sim 10$ TeV. An estimator of \Xmax is obtained, event-by-event, from its correlation with the distribution of the arrival time of the particles at the ground, or the signal at the ground for lower energies. An estimator of $E_0$ is obtained, event-by-event, using a parametrization that has as inputs the total measured energy at the ground, the amount of energy contained in a region near to the shower core and the estimated \Xmax. Resolutions about $40(20)g/c{\mathrm{m}}^2$ and about $30(20)\%$ for, respectively, \Xmax and $E_0$ at $1(10)\mathrm{TeV}$ energies are obtained, considering vertical showers. The obtained results are auspicious and can lead to the opening of new physics avenues for large wide field-of-view gamma-ray observatories. The dependence of the resolutions with experimental conditions is discussed.

   hep-phastro-ph.HEhep-exEPJC(2021)·4 citations
6. 06*

   Pion gravitational form factors in a relativistic theory of composite particles

   A.F. Krutov🇷🇺 · V.E. Troitsky🇷🇺

   We extend our relativistic theory of electroweak properties of composite systems to describe simultaneously the gravitational form factors of hadrons. The approach is based on a version of the instant-form relativistic quantum mechanics and makes use of the modified impulse approximation. We exploit the general method of the relativistic invariant parametrizaton of local operators to write the energy-momentum tensor of a particle with an arbitrary spin. We use the obtained results to calculate the gravitational form factors of the pion assuming point-like constituent quarks. All but one parameters of our first-principle model were fixed previously in works on electromagnetic form factors. The only free parameter, $D_q$, is a characteristic of the gravitational form factor of a constituent quark. The derived form factors of the pion satisfy the constraints given by the general principles of the quantum field theory of hadron structure. The calculated gravitational form factors and gravitational mean-square radius are in a reasonable agreement with known results.

   hep-phPRD(2021)·29 citations
7. 07*

   Status of low mass LSP in SUSY

   Rahool Kumar Barman🇮🇳 · Genevieve Belanger🇫🇷 · Rohini M. Godbole🇮🇳

   In this article we review the case for a light ($<m_{h_{125}}/2$) neutralino and sneutrino being a viable Dark Matter (DM) candidate in Supersymmetry(SUSY). To that end we recapitulate, very briefly, three issues related to the DM which impact the discussions : calculation of DM relic density, detection of the DM in Direct and Indirect experiments and creation /detection at the Colliders. In case of SUSY, the results from Higgs and SUSY searches at the colliders also have implications for the DM mass and couplings. In view of the constraints coming from all these sources, the possibility of a light neutralino is all but ruled out for the constrained MSSM : cMSSM. The pMSSM, where the gaugino masses are not related at high scale, is also quite constrained and under tension in case of thermal DM and will be put to very stern test in the near future in Direct Detection (DD) experiments as well as by the LHC analyses. However in the pMSSM with modified cosmology and hence non-thermal DM or in the NMSSM, a light neutralino is much more easily accommodated. A light RH sneutrino is also still a viable DM candidate although it requires extending the MSSM with additional singlet neutrino superfields. All of these possibilities can be indeed tested jointly in the upcoming SUSY-electroweakino and Higgs searches at the HL/HE luminosity LHC, the upcoming experiments for the Direct Detection (DD) and indirect detection for the DM as well as the high precision electron-positron colliders under planning.

   hep-phEur.Phys.J.ST(2020)·27 citations
8. 08*

   Perturbative Reheating in the Mixed Higgs-$R^2$ Model

   Minxi He🇯🇵

   The preheating process in the mixed Higgs-$R^2$ model has been investigated in depth recently, but the analysis of perturbative reheating is still missing. In this paper, we discuss the effect of perturbative decay during (p)reheating in this model. It is shown that perturbative decay can play an important role throughout the whole reheating process. Depending on the model parameters, perturbative decay can affect different stages of the reheating. We study the perturbative reheating with and without the presence of early preheating stage, and calculate the reheating temperature and the duration of the whole perturbative process. We find that the detail of the early preheating stage may not affect the final reheating temperature while it can affect the number of e-folds of reheating.

   hep-phastro-ph.COgr-qchep-thJCAP(2021)·30 citations
9. 09*

   Boosted top quark tagging and polarization measurement using machine learning

   Soham Bhattacharya🇩🇪 · Monoranjan Guchait🇮🇳 · Aravind H. Vijay🇮🇳

   Machine learning techniques are used for treating jets as images to explore the performance of boosted top quark tagging. Tagging performances are studied in both hadronic and leptonic channels of top quark decay, employing a convolutional neural network (CNN) based technique along with boosted decision trees (BDT). This computer vision approach is also applied to distinguish between left and right polarized top quarks. In this context, an experimentally measurable asymmetry variable is proposed to estimate the polarization. Results indicate that the CNN based classifier is more sensitive to top quark polarization than the standard kinematic variables. It is observed that the overall tagging performance in the leptonic channel is better than the hadronic case, and the former also serves as a better probe for studying polarization.

   hep-phPRD(2022)·21 citations
10. 10*

    $\mathcal{O}({\alpha }_s{v}^2)$ corrections to hadronic decay of vector quarkonia

    Wen-Long Sang🇨🇳 · Feng Feng🇨🇳 · Yu Jia🇨🇳

    Within the nonrelativistic QCD (NRQCD) factorization framework, we compute the $\mathcal{O}({\alpha }_s{v}^2)$ corrections to the hadronic decay rate of vector quarkonia, exemplified by $J/\psi$ and ${\rm Y}$. Setting both the renormalization and NRQCD factorization scales to be $m_Q$, we obtain $\Gamma (J/\psi \to \mathrm{LH})=0.0716\frac{{\alpha }_s^3}{m_c^2}⟨{\mathcal{O}}_1({}^3{S}_1){⟩}_{J/\psi }[1-1.19{\alpha }_s+(-5.32+3.03{\alpha }_s)⟨v^2{⟩}_{J/\psi }]$ and $\Gamma ({\rm Y}\to \mathrm{LH})=0.0716\frac{{\alpha }_s^3}{m_b^2}⟨{\mathcal{O}}_1({}^3{S}_1){⟩}_{{\rm Y}}[1-1.56{\alpha }_s+(-5.32+4.61{\alpha }_s)⟨v^2{⟩}_{{\rm Y}}]$. We confirm the previous calculation of $\mathcal{O}({\alpha }_s)$ corrections on a diagram-by-diagram basis, with the accuracy significantly improved. For $J/\psi$ hadronic decay, we find that the $\mathcal{O}({\alpha }_s{v}^2)$ corrections are moderate and positive, nevertheless unable to counterbalance the huge negative corrections. On the other hand, the effect of $\mathcal{O}({\alpha }_s{v}^2)$ corrections for ${\rm Y}(nS)$ is sensitive to the $\mathcal{O}(v^2)$ NRQCD matrix elements. With the appropriate choice of the NRQCD matrix elements, our theoretical predictions for the decay rates may be consistent with the experimental data for ${\rm Y}(1S,2S)\to \mathrm{LH}$. As a byproduct, we also present the theoretical predictions for the branching ratio of $J/\psi ({\rm Y})\to 3\gamma$ accurate up to $\mathcal{O}({\alpha }_s{v}^2)$.

    hep-phhep-exPRD(2020)·6 citations
11. 11*

    The subtraction contribution to the muonic-hydrogen Lamb shift: a point for lattice QCD calculations of the polarizability effect

    Franziska Hagelstein (PSI)🇨🇭 · Vladimir Pascalutsa (JGU Mainz)🇩🇪

    The proton-polarizability contribution to the muonic-hydrogen Lamb shift is a major source of theoretical uncertainty in the extraction of the proton charge radius. An empirical evaluation of this effect, based on the proton structure functions, requires a systematically improvable calculation of the "subtraction function", possibly using lattice QCD. We consider a different subtraction point, with the aim of accessing the subtraction function directly in lattice calculations. A useful feature of this subtraction point is that the corresponding contribution of the structure functions to the Lamb shift is suppressed. The whole effect is dominated by the subtraction contribution, calculable on the lattice.

    hep-phhep-latnucl-thphysics.atom-phNPA(2021)·16 citations
12. 12*

    Bottom-quark production at hadron colliders: fully differential predictions in NNLO QCD

    Stefano Catani🇮🇹 · Simone Devoto🇨🇭 · Massimiliano Grazzini🇨🇭 · Stefan Kallweit🇮🇹 · Javier Mazzitelli🇩🇪

    We report on the first fully differential calculation of the next-to-next-to-leading-order (NNLO) QCD radiative corrections to the production of bottom-quark pairs at hadron colliders. The calculation is performed by using the $q_T$ subtraction formalism to handle and cancel infrared singularities in real and virtual contributions. The computation is implemented in the Matrix framework, thereby allowing us to efficiently compute arbitrary infrared-safe observables in the four-flavour scheme. We present selected predictions for bottom-quark production at the Tevatron and at the LHC at different collider energies, and we perform some comparisons with available experimental results. We find that the NNLO corrections are sizeable, typically of the order of $25$-$35\%$, and they lead to a significant reduction of the perturbative uncertainties. Therefore, their inclusion is crucial for an accurate theoretical description of this process.

    hep-phhep-exJHEP(2021)·98 citations
13. 13*

    Dyson-Schwinger approach to pion-nucleon scattering using time-ordered perturbation theory

    B. Blankleider🇦🇺 · J. L. Wray🇦🇺 · A. N. Kvinikhidze🇬🇪

    We present a simple description of pion-nucleon ($\pi N$) scattering taking into account the full complexity of pion absorption and creation on the nucleon. To do this we solve Dyson-Schwinger equations within the framework of Time-Ordered Perturbation Theory. This enables us to construct partial wave separable $\pi N$ t matrices that can be useful in models of nuclear processes involving fully dressed nucleons. At the same time, our approach demonstrates features of Quantum Field Theory, like particle dressing, renormalisation, and the use of Dyson-Schwinger equations, in a non-relativistic context that is maximally close to that of Quantum Mechanics. For this reason, this article may also be of pedagogical interest.

    ↳ nucl-thhep-phAIP Adv.(2021)·1 citation
14. 14*

    Progress towards the first measurement of charm baryon dipole moments

    S. Aiola🇮🇹 · L. Bandiera🇮🇹 · G. Cavoto🇮🇹 · F. De Benedetti🇮🇹 · J. Fu🇮🇹 · V. Guidi🇮🇹 · L. Henry🇪🇸 · D. Marangotto🇮🇹 · F. Martinez Vidal🇪🇸 · V. Mascagna🇮🇹 · J. Mazorra de Cos🇪🇸 · A. Mazzolari🇮🇹 and 9 other authors

    Electromagnetic dipole moments of short-lived particles are sensitive to physics within and beyond the Standard Model of particle physics but have not been accessible experimentally to date. To perform such measurements it has been proposed to exploit the spin precession of channeled particles in bent crystals at the LHC. Progress that enables the first measurement of charm baryon dipole moments is reported. In particular, the design and characterization on beam of silicon and germanium bent crystal prototypes, the optimization of the experimental setup, and advanced analysis techniques are discussed. Sensitivity studies show that first measurements of ${\Lambda }_c^{+}$ and ${\Xi }_c^{+}$ baryon dipole moments can be performed in two years of data taking with an experimental setup positioned upstream of the LHCb detector.

    ↳ hep-exhep-phPRD(2021)·43 citations
15. 15*

    Effective shear and bulk viscosities for anisotropic flow

    Fernando G. Gardim🇧🇷 · Jean-Yves Ollitrault🇫🇷

    We evaluate the viscous damping of anisotropic flow in heavy-ion collisions for arbitrary temperature-dependent shear and bulk viscosities. We show that the damping is solely determined by effective shear and bulk viscosities, which are weighted averages over the temperature. We determine the relevant weights for nucleus-nucleus collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV and 200 GeV, corresponding to the maximum LHC and RHIC energies, by running ideal and viscous hydrodynamic simulations. The effective shear viscosity is driven by temperatures below $210$ MeV at RHIC, and below $280$ MeV at the LHC, with the largest contributions coming from the lowest temperatures, just above freeze-out. The effective bulk viscosity is driven by somewhat higher temperatures, corresponding to earlier stages of the collision. We show that at a fixed collision energy, the effective viscosity is independent of centrality and system size, to the same extent as the mean transverse momentum of outgoing hadrons. The variation of viscous damping is determined by Reynolds number scaling.

    ↳ nucl-thhep-phnucl-exPRC(2021)·23 citations
16. 16*

    Reheating in the kination epoch via multi-channel decay of gravitationally created massive scalars

    Juho Lankinen🇫🇮 · Oskari Kerppo🇫🇮 · Iiro Vilja🇫🇮

    We provide a detailed study of reheating in the kination regime in a scenario where the particle content is produced by gravitational production of massive scalars decaying into massless scalars and fermions which eventually reheat the Universe. A detailed calculation is given by using Boltzmann equations and decay rates obtained using formalism of quantum field theory in curved spacetime. By numerical calculations the reheating temperature is found to be in the $10^9$-$10^{13}$ GeV regime. Moreover, the fermionic channel of decay is found to be the dominant channel of decay when the mass $m$ of the decaying particle is small raising the reheating temperature as opposed to a single scalar decay channel.

    ↳ gr-qcastro-ph.COhep-phhep-thPRD(2021)·2 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.