Tue·Aug 25, 2020Tuesday·August 25, 2020

1. 01*

   Dynamical Inflection Point Inflation

   Yang Bai🇺🇸 · Daniel Stolarski🇨🇦

   We provide a mechanism to obtain multiple inflection points for the inflaton potential based on the Coleman-Weinberg potential. The key ingredient is the existence of zeros of the inflaton quartic coupling beta function, which can be simply realized by a sign change of a gauge coupling beta function at a massive threshold scale in gauge-Yukawa models. A universal inflaton potential emerges for a wide range of models and can accommodate the experimental data in the small-field inflation scenario. While the ratio of tensor over scalar amplitudes is predicted to be small, the running of the scalar spectral index, ${\alpha }_s$, has branches with both positive and negative values. The positive branch with ${\alpha }_s\gtrsim 0.002$ will be tested by the coming cosmic microwave background experiments.

   hep-phastro-ph.COgr-qcJCAP(2021)·8 citations
2. 02*

   Constructing massive on-shell contact terms

   Gauthier Durieux🇮🇱 · Teppei Kitahara🇮🇱 · Camila S. Machado🇩🇪 · Yael Shadmi🇮🇱 · Yaniv Weiss🇮🇱

   The purely on-shell approach to effective field theories requires the construction of independent contact terms. Employing the little-group-covariant massive-spinor formalism, we present the first systematic derivation of independent four-point contact terms involving massive scalars, spin-1/2 fermions, and vectors. Independent three-point amplitudes are also listed for massive particles up to spin-3. We make extensive use of the simple relations between massless and massive amplitudes in this formalism. Our general results are specialized to the (broken-phase) particle content of the electroweak sector of the standard model. The (anti)symmetrization among identical particles is then accounted for. This work opens the way for the on-shell computation of massive four-point amplitudes.

   hep-phhep-thJHEP(2020)·78 citations
3. 03*

   Another Unorthodox Introduction to QCD and now Machine Learning

   Andrew J. Larkoski🇺🇸

   These are lecture notes presented at the online 2020 Hadron Collider Physics Summer School hosted by Fermilab. These are an extension of lectures presented at the 2017 and 2018 CTEQ summer schools in arXiv:1709.06195 and still introduces perturbative QCD and its application to jet substructure from a bottom-up perspective based on the approximation of QCD as a weakly-coupled, conformal field theory. With machine learning becoming an increasingly important tool of particle physics, I discuss its utility exclusively from the biased view for increasing human knowledge. A simple argument that the likelihood for quark versus gluon discrimination is infrared and collinear safe is presented as an example of this approach. End-of-lecture exercises are also provided.

   hep-phhep-ex3 citations
4. 04*

   Precision Nuclear-Spin Effects in Atoms: EFT Methods for Reducing Theory Errors

   L. Zalavari🇨🇦 · C. P. Burgess🇨🇦 · P. Hayman🇨🇦 · M. Rummel🇨🇦

   We use effective field theory to compute the influence of nuclear structure on precision calculations of atomic energy levels. As usual, the EFT's effective couplings correspond to the various nuclear properties (such as the charge radius, nuclear polarizabilities, Friar and Zemach moments {\it etc.}) that dominate its low-energy electromagnetic influence on its surroundings. By extending to spinning nuclei the arguments developed for spinless ones in {\tt arXiv:1708.09768}, we use the EFT to show -- to any fixed order in $Z\alpha$ (where $Z$ is the atomic number and $\alpha$ the fine-structure constant) and the ratio of nuclear to atomic size -- that nuclear properties actually contribute to electronic energies through fewer parameters than the number of these effective nuclear couplings naively suggests. Our result is derived using a position-space method for matching effective parameters to nuclear properties in the EFT, that more efficiently exploits the simplicity of the small-nucleus limit in atomic systems. By showing that precision calculations of atomic spectra depend on fewer nuclear uncertainties than naively expected, this observation allows the construction of many nucleus-independent combinations of atomic energy differences whose measurement can be used to test fundamental physics (such as the predictions of QED) because their theoretical uncertainties are not limited by the accuracy of nuclear calculations. We provide several simple examples of such nucleus-free predictions for Hydrogen-like atoms.

   hep-phhep-thphysics.atom-phAnnals Phys.(2021)·7 citations
5. 05*

   Nuclear Predictions for $H$ Spectroscopy without Nuclear Errors

   C. P. Burgess🇨🇦 · P. Hayman🇨🇦 · Markus Rummel🇨🇦 · László Zalavári🇨🇦

   Nuclear-structure effects often provide an irreducible theory error that prevents using precision atomic measurements to test fundamental theory. We apply newly developed effective field theory tools to Hydrogen atoms, and use them to show that (to the accuracy of present measurements) all nuclear finite-size effects (e.g. the charge radius, Friar moments, nuclear polarizabilities, recoil corrections, Zemach moments {\it etc.}) only enter into atomic energies through exactly two parameters, independent of any nuclear-modelling uncertainties. Since precise measurements are available for more than two atomic levels in Hydrogen, this observation allows the use of precision atomic measurements to eliminate the theory error associated with nuclear matrix elements. We apply this reasoning to the seven atomic measurements whose experimental accuracy is smaller than 10 kHz to provide predictions for nuclear-size effects whose theoretical accuracy is not subject to nuclear-modelling uncertainties and so are much smaller than 1 kHz. Furthermore, the accuracy of these predictions can improve as atomic measurements improve, allowing precision fundamental tests to become possible well below the 'irreducible' error floor of nuclear theory.

   hep-phhep-thphysics.atom-phPLA(2021)·7 citations
6. 06*

   Global oscillation data analysis on the $3\nu$ mixing without unitarity

   Zhuojun Hu🇨🇳 · Jiajie Ling🇨🇳 · Jian Tang🇨🇳 · TseChun Wang🇨🇳

   We present results of a combined analysis in neutrino oscillations without unitarity assumption in the $3\nu$ mixing picture. Constraints on neutrino mixing matrix elements are based on recent data from the reactor, solar and long-baseline accelerator neutrino oscillation experiments. The current data are consistent with the standard $3\nu$ scheme. The precision on different matrix elements can be as good as a few percent at $3\sigma$ CL, and is mainly limited by the experimental statistical uncertainty. The ${\nu }_e$ related elements are the most precisely measured among all sectors with the uncertainties $<20\%$. The measured leptonic CP violation is very close to the one assuming the standard $3\nu$ mixing. The deviations on normalization and the unitarity triangle closure are confined within $\mathcal{O}(10^{-3})$, $\mathcal{O}(10^{-2})$ and $\mathcal{O}(10^{-1})$, for ${\nu }_e$, ${\nu }_{\mu }$ and ${\nu }_{\tau }$ sectors, respectively. We look forward to the next-generation neutrino oscillation experiments \textit{such as} DUNE, T2HK, and JUNO, especially the precise measurements on ${\nu }_{\tau }$ oscillations, to significantly improve the precision of unitarity test on the $3\nu$ mixing matrix.

   hep-phJHEP(2021)·32 citations
7. 07*

   $(g-2{)}_{\mu }$ Versus $K\to \pi +E_{miss}$ Induced by the $(B-L{)}_{23}$ Boson

   Zhaofeng Kang🇨🇳 · Yoshihiro Shigekami🇨🇳

   To address the long-standing $(g-2{)}_{\mu }$ anomaly via a light boson, in Ref. [1] we proposed to extend the standard model (SM) by the local $(B-L{)}_{23}$, under which only the second and third generations of fermions are charged. It predicts an invisible $Z^{\prime }$ with mass $\mathcal{O}(100)$ MeV, and moreover it has flavor-changing neutral current (FCNC) couplings to the up-type quarks at tree level. Such a $Z^{\prime }$, via $K_L\to {\pi }^0+Z^{\prime }(\to \nu \bar{\nu })$ at loop level, may be a natural candidate to account for the recent KOTO anomaly. In this article, we investigate this possibility, to find that $Z^{\prime }$ can readily do this job if it is no longer responsible for the $(g-2{)}_{\mu }$ anomaly. We further find that both anomalies can be explained with moderate tuning of the CP violation, but may contradict the $B$ meson decays.

   hep-phhep-exJHEP(2021)·4 citations
8. 08*

   Soft anomalous dimensions and resummation in QCD

   Nikolaos Kidonakis🇺🇸

   I discuss and review soft anomalous dimensions in QCD that describe soft-gluon threshold resummation for a wide range of hard-scattering processes. The factorization properties of the cross section in moment space and renormalization-group evolution are implemented to derive a general form for differential resummed cross sections. Detailed expressions are given for the soft anomalous dimensions at one, two, and three loops, including some new results, for a large number of partonic processes involving top quarks, electroweak bosons, Higgs bosons, and other particles in the Standard Model and beyond.

   hep-phhep-thUniverse(2020)·12 citations
9. 09*

   Constraints on the charged-current non-standard neutrino interactions induced by the gauge boson $W^{\prime }$

   ChongXing Yue🇨🇳 · XueJia Cheng🇨🇳

   Many new physics scenarios predict the existence of the extra charged gauge boson $W^{\prime }$, which can induce the charged-current (CC) non-standard neutrino interactions (NSI). We investigate the constraints on the CC NSI in model-independent fashion via considering the $W^{\prime }$ contributions to the lepton flavor violating (LFV) decays ${\ell }_i\to {\ell }_j\gamma$, the pure leptonic flavor conservation (FC) decays ${\ell }_i\to {\ell }_j{\nu }_i\overline{{\nu }_j}$, leptonic decays of charged pion meson, semileptonic $\tau$ decays, and superallowed $\beta$ decays. We find that the constraints on the pure leptonic CC NSI are generally stronger than the ones for the CC NSI with first generation quarks. The most stringent constraints on the CC NSI arise from the LFV decay $\mu \to e\gamma$.

   hep-phNPB(2021)·8 citations
10. 10*

    Simple implementation of color coherence for the resumation of soft BDMPS-Z gluons

    João Barata🇪🇸 · Fabio Dominguez🇪🇸 · Carlos Salgado🇺🇸 · Victor Vila🇪🇸

    The evolution of QCD jets under the influence of a dense colored medium leads to the non trivial modification of the gluon emission spectrum. In the multiple soft scattering regime, for sufficiently large media, soft and wide angle emissions can be resummed (in the planar limit of QCD) due to the small formation time of each gluon emission. Similarly to DGLAP evolution, such cascades correspond to pure Markovian processes and interferences between partons are neglected. In this strict limit, color coherence effects are absent. In the vacuum this coherence effect is critical to guarantee that the shower is angular ordered. In the medium, it is known that such color coherence effects might play a role in suppressing radiation at intermediate emission angles. We present a simple procedure to implement color (de)coherence effects into the in-medium evolution equations obtained in the pure Markovian approximation. We verify that the result obtained is in accordance with previous studies regarding the role of in-medium color coherence in the evolution of the QCD antenna. The new evolution equation incorporates a novel emission kernel which enforces color coherence between emitters.

    hep-phPoS(2021)·0 citations
11. 11*

    Role of scalar $a_0(980)$ in the single Cabibbo Suppressed process $D^{+}\to {\pi }^{+}{\pi }^0\eta$

    Man-Yu Duan🇨🇳 · Jun-Ya Wang🇨🇳 · Guan-Ying Wang🇨🇳 · En Wang🇨🇳 · De-Min Li🇨🇳

    Taking into account that the scalar $a_0(980)$ can be dynamically generated from the pseudoscalar-pseudoscalar interaction within the chiral unitary approach, we have studied the single Cabibbo-suppressed process $D^{+}\to {\pi }^{+}{\pi }^0\eta$. We find clear peaks of $a_0(980{)}^{+}$ and $a_0(980{)}^0$ in the ${\pi }^{+}\eta$ and ${\pi }^0\eta$ invariant mass distributions, respectively. The predicted Dalitz plots of $D^{+}\to {\pi }^{+}{\pi }^0\eta$ also manifest the significant signals for $a_0(980{)}^{+}$ and $a_0(980{)}^0$ states. The uncertainties of the results due to the free parameters are also discussed. Our study shows that the process $D^{+}\to {\pi }^{+}{\pi }^0\eta$ can be used to explore the nature of the scalar $a_0(980)$, thus we encourage the experimental physicists to measure this reaction with more precision.

    hep-phhep-exEPJC(2020)·48 citations
12. 12*

    Four-quark states from functional methods

    Gernot Eichmann🇵🇹 · Christian S. Fischer🇩🇪 · Walter Heupel🇩🇪 · Nico Santowsky🇩🇪 · Paul C. Wallbott🇩🇪

    In this feature article we summarise and highlight aspects of the treatment of four-quark states with functional methods. Model approaches to those exotic mesons almost inevitably have to assume certain internal structures, e.g. by grouping quarks and antiquarks into (anti-)diquark clusters or heavy-light $q\bar{q}$ pairs. Functional methods using Dyson-Schwinger and Bethe-Salpeter equations can be formulated without such prejudice and therefore have the potential to put these assumptions to test and discriminate between such models. So far, functional methods have been used to study the light scalar-meson sector and the heavy-light sector with a pair of charmed and a pair of light quarks in different quantum number channels. For all these states, the dominant components in terms of internal two-body clustering have been identified. It turns out that chiral symmetry breaking plays an important role for the dominant clusters in the light meson sector (in particular for the scalar mesons) and that this property is carried over to the heavy-light sector. Diquark-antidiquark components, on the other hand, turn out to be almost negligible for most states with the exception of open-charm heavy-light exotics.

    hep-phhep-latFew Body Syst.(2020)·47 citations
13. 13*

    Bounds on Relativistic Deformed Kinematics from the Physics of the Universe Transparency

    J.M. Carmona🇪🇸 · J.L. Cortés🇪🇸 · L. Pereira🇪🇸 · J.J. Relancio🇪🇸

    We analyze the kinematics of electron-positron production in a photon-photon interaction when one has a modification of the special relativistic kinematics as a power expansion in the inverse of a new high-energy scale. We derive the equation for the threshold energy of this reaction to first order in this expansion, including the effects due to a modification of the energy-momentum conservation equation. In contrast with the Lorentz invariance violation case, a scale of the order of a few TeV is found to be compatible with the observations of very high-energy cosmic gamma rays in the case of a modification compatible with the relativity principle.

    hep-phhep-thSymmetry(2020)·13 citations
14. 14*

    Constraints on General Light Mediators from PandaX-II Electron Recoil Data

    Amir N. Khan🇩🇪

    PandaX-II has analyzed their complete data set of the electron recoil energy spectrum and has confirmed the XENON1T (1-7) keV excess, although the excess was also found compatible with the total background. Treating the background as well known, in which case it provides a good fit to the observed spectrum, one can expect stronger constraints on any new physics model with this data. With this motivation, we derive constraints on the new general vector (V), axial-vector (A), scalar (S) and pseudoscalar (P) interactions if any of them contribute to the neutrino-electron elastic scattering. The derived constraints on the couplings at $90\%$ C.L., respectively, are $g_{V^{{}^{\prime }}}\lesssim 32\times 10^{-7}$ for the mediator mass $\lesssim 10$ keV, $g_{A^{{}^{\prime }}}\lesssim 34\times 10^{-7}$ for mass $\lesssim 10$ keV, $g_S\lesssim 49\times 10^{-7}$ for mass $\lesssim 20$ keV and $g_P\lesssim 67\times 10^{-7}$ for mass $\lesssim 30$ keV.

    hep-phhep-exhep-thPLB(2021)·18 citations
15. 15*

    Diffractive production of $\Lambda$ hyperons in the high-energy limit of strong interactions

    Francesco Giovanni Celiberto🇮🇹 · Dmitry Yu. Ivanov🇷🇺 · Alessandro Papa🇮🇹

    We propose the study of the inclusive production of two $\Lambda$ hyperons or a single $\Lambda$-particle in association with a jet, featuring high transverse momenta and large separation in rapidity, as a probe channel of the resummation of energy logarithms in the QCD perturbative series. We give predictions, shaped on kinematic ranges typical of CMS and of the backward CASTOR detector, for cross section and azimuthal-correlation moments between the two emitted objects, showing how considering the tag of $\Lambda$ baryons eases the comparison between theoretical results and experimental data in the phenomenological context of semi-hard reactions.

    hep-phPRD(2020)·76 citations
16. 16*

    Aspects and applications of nonlocal Lorentz-violation

    Christopher D. Carone🇺🇸

    We consider simple scalar theories with quadratic terms that are nonlocal and Lorentz violating. Unlike similar Lorentz-invariant nonlocal theories that we have considered previously, the theories studied here are both ghost-free and unitary as formulated in Minkowski space. We explore the possibility that the scale of nonlocality could be low in a dark sector, where the stringent constraints on the violation of Lorentz invariance may be accommodated via the weak coupling to the standard model. We point out that long-range forces may originate from such a sector and be distinguishable from more conventional beyond-the-standard model possibilities. We present a model in which a nonlocal, Lorentz-violating dark sector communicates with the standard model via a sector of heavy vector-like fermions, a concrete framework in which phenomenological constraints and signals can be investigated.

    hep-phPRD(2020)·8 citations
17. 17*

    Higgs boson decays into narrow di-photon jets and their search strategies at the Large Hadron Collider

    Benjamin Sheff🇺🇸 · Noah Steinberg🇺🇸 · James D. Wells🇺🇸

    In many extensions of the Standard Model the Higgs boson can decay into two light scalars each of which then subsequently decay into two photons. The underlying event is h $\to$ 4$\gamma$, but the kinematics from boosted light scalar decays combined with realistic detector resolutions may fail to register the events in straightforward categories and thus may be lost. In this article we investigate the phase space for highly boosted di-photon events from these exotic Higgs decays and discuss search strategies that aim to capture and label events in this difficult region. In the process we develop a new category, $\xi$-jets, which identifies with high selectivity highly collimated di-photon decay modes of the Higgs boson.

    hep-phhep-exPRD(2021)·20 citations
18. 18*

    QCD Beyond Leading Power

    Gherardo Vita🇺🇸

    In this thesis I study the infrared limits of QCD beyond leading power by developing effective quantum field theory techniques. I introduce the motivations for studying this subject both as a tool to deepen our understanding of the infrared structure of gauge theory amplitudes and cross sections in the soft, collinear and Regge limit as well as to improve predictions for collider observables. Using and extending the framework of Soft and Collinear Effective Theory (SCET), I explore the ingredients of factorization beyond leading power constructing subleading hard scattering operators and radiative jet and soft functions for processes such as Higgs production and Drell-Yan. I introduce new subleading power gauge invariant objects, the $\theta$-jet and $\theta$-soft functions, which arise in the renormalization of subleading power operators. I use them to achieve the first resummation of collinear and soft logarithms beyond leading power for a collider observable in QCD. I study the perturbative power corrections to differential distributions for color singlet production at the LHC retaining the full dependence on the kinematics of the color singlet. I highlight and solve the subtleties related to the regularization of rapidity divergences beyond leading power for which I propose a new regulator, the pure rapidity regulator. I present a new method to employ cutting edge multiloop techniques for the computation of the expansions of cross sections in the collinear limit. This allows the extraction of universal ingredients arising in the collinear limit of QCD to an unprecedented level of precision in perturbation theory. Finally, I study the Regge limit at the amplitude and cross section level beyond leading power, developing a Lagrangian formalism for the treatment of fermion mediated forward scattering processes in QCD and applying it to obtain the quark reggeization and BFKL resummation.

    hep-phnucl-th4 citations
19. 19*

    Composite Dark Matter from Strongly-Interacting Chiral Dynamics

    Roberto Contino🇮🇹 · Alessandro Podo🇮🇹 · Filippo Revello🇮🇹

    A class of chiral gauge theories is studied with accidentally-stable pseudo Nambu-Goldstone bosons playing the role of dark matter (DM). The gauge group contains a vector-like dark color factor that confines at energies larger than the electroweak scale, and a $\mathrm{U}(1{)}_D$ factor that remains weakly coupled and is spontaneously broken. All new scales are generated dynamically, including the DM mass, and the IR dynamics is fully calculable. We analyze minimal models of this kind with dark fermions transforming as non-trivial vector-like representations of the Standard Model (SM) gauge group. In realistic models, the DM candidate is a SM singlet and comes along with charged partners that can be discovered at high-energy colliders. The phenomenology of the lowest-lying new states is thus characterized by correlated predictions for astrophysical observations and laboratory experiments.

    hep-phastro-ph.COJHEP(2021)·37 citations
20. 20*

    Effective field theory analysis of dark matter-standard model interactions with spin one mediators

    Fabiola Fortuna🇲🇽 · Pablo Roig🇲🇽 · José Wudka🇺🇸

    We analyze interactions between dark matter and standard model particles with spin one mediators in an effective field theory framework. In this paper, we are considering dark particles masses in the range from a few MeV to the mass of the $Z$ boson. We use bounds from different experiments: $Z$ invisible decay width, relic density, direct detection experiments, and indirect detection limits from the search of gamma-ray emissions and positron fluxes. We obtain solutions corresponding to operators with antisymmetric tensor mediators that fulfill all those requirements within our approach.

    hep-phhep-exJHEP(2021)·17 citations
21. 21*

    A solar origin of the XENON1T excess without stellar cooling problems

    Sabyasachi Chakraborty🇺🇸 · Tae Hyun Jung🇺🇸 · Vazha Loladze🇺🇸 · Takemichi Okui🇺🇸 · Kohsaku Tobioka🇺🇸

    Solar interpretations of the recent XENON1T excess events, such as axion or dark photon emissions from the sun, are thought to be at odds with stellar cooling bounds from the horizontal branch stars and red giants. We propose a simple effective field theory of a dark photon in which a $Z_2$ symmetry forbids a single dark photon emission in the dense stars, thereby evading the cooling bounds, while the $Z_2$ is spontaneously broken in the vacuum and sun, thereby explaining the XENON1T excess. The scalar responsible for the $Z_2$ breaking has an extremely flat potential, but the flatness can be maintained under quantum corrections. The UV completion of the EFT generally requires the existence of new electrically charged particles with sub-TeV masses with $O(1)$ couplings to the dark photon, offering the opportunity to test the scenario further and opening a new window into the dark sector in laboratory experiments.

    hep-phPRD(2020)·12 citations
22. 22*

    QED factorization of non-leptonic $B$ decays

    Martin Beneke🇩🇪 · Philipp Böer🇩🇪 · Jan-Niklas Toelstede🇩🇪 · K. Keri Vos🇩🇪

    We show that the QCD factorization approach for $B$-meson decays to charmless hadronic two-body final states can be extended to include electromagnetic corrections. The presence of electrically charged final-state particles complicates the framework. Nevertheless, the factorization formula takes the same form as in QCD alone, with appropriate generalizations of the definitions of light-cone distribution amplitudes and form factors to include QED effects. More precisely, we factorize QED effects above the strong interaction scale ${\Lambda }_{\mathrm{QCD}}$ for the non-radiative matrix elements $⟨M_1{M}_2|Q_i|\bar{B}⟩$ of the current-current operators from the effective weak interactions. The rates of the branching fractions for the infrared-finite observables $\bar{B}\to M_1{M}_2(\gamma )$ with photons of maximal energy $\Delta E\ll {\Lambda }_{\mathrm{QCD}}$ is then obtained by multiplying with the soft-photon exponentiation factors. We provide first estimates for the various electromagnetic corrections, and in particular quantify their impact on the $\pi K$ ratios and sum rules that are often used as diagnostics of New Physics.

    hep-phhep-thJHEP(2020)·46 citations
23. 23*

    Local energy-momentum conservation and initial conditions for quark-gluon plasma evolution in nucleus-nucleus collisions at SPS and RHIC BES energies

    Antoni Szczurek🇵🇱

    We investigate consequences of local energy-momentum conservation for initial eccentricity coefficients in heavy ion collisions at not too high energies relevant for CERN SPS and RHIC BES. Different models of energy density available for pion production are considered. We study dependence of eccentricity coefficients on space-time rapidity for different impact parameters. The naive formula how to define eccentricities breaks with our initial conditions and must be corrected. We predict considerable eccentricities for ${ϵ}_{1,2,3,4}$ and specific dependence on space-time rapidity as well as on impact parameter for lower energies. The effect becomes smaller at larger energies when restricting to narrow rapidity interval arround zero. Our predictions are in principle input for further hydrodynamical evolution but it is not clear whether they can be easily used. Our initial condition suggest a strong preequilibrium phase which is difficult for modelling.

    ↳ nucl-thhep-ph0 citations
24. 24*

    Configuration entropy description of charmonium dissociation under the influence of magnetic fields

    Nelson R. F. Braga🇧🇷 · Rodrigo da Mata🇧🇷

    Heavy ion collisions, produced in particle accelerators, lead to the formation of a new state of matter, known as the quark gluon plasma. It is not possible to observe directly the plasma, where quarks and gluons are not confined into hadrons. All the available information comes from the particles that reach the detectors after the strongly interacting matter hadronizes. Among those particles, one that plays an important role is the charmonium J/$\psi$ heavy meson, made of a $c\bar{c}$ quark anti-quark pair. The fraction of such particles produced in a heavy ion collision is related to the dissociation level caused by the plasma. On the other hand, the dissociation of $J/\Psi$ in the plasma is influenced by the temperature and the density of the medium and also by the presence of magnetic fields, that are produced in non central collisions. A very interesting tool to study stability of physical systems is the configuration entropy (CE). In recent years many examples in various kinds of physical systems appeared in the literature, where an increase in the CE is associated with an increase in the instability of the system. In this article we calculate the CE for charmonium quasistates inside a plasma with a magnetic field background, in order to investigate how the instability, corresponding in this case to the dissociation in the thermal medium, is translated into the dependence of the CE on the field.

    ↳ hep-thhep-phPLB(2020)·43 citations
25. 25*

    Testing Primordial Black Holes as Dark Matter in Supergravity from Gravitational Waves

    Yermek Aldabergenov🇹🇭 · Andrea Addazi🇨🇳 · Sergei V. Ketov🇯🇵

    We explore the Gravitational Waves (GW) phenomenology of a simple class of supergravity models that can explain and unify inflation and Primordial Black Holes (PBH) as Dark Matter (DM). Our (modified) supergravity models naturally lead to a two-field attractor-type double inflation, whose first stage is driven by Starobinsky scalaron and the second stage is driven by another scalar belonging to a supergravity multiplet. The PBHs formation in our supergravity models is efficient, compatible with all observational constraints, and predicts a stochastic GW background. We compute the PBH-induced GW power spectrum and show that GW signals can be detected within the sensitivity curves of the future space-based GW interferometers such as LISA, DECIGO, TAIJI and TianQin projects, thus showing predictive power of supergravity in GW physics and their compatibility.

    ↳ hep-thastro-ph.COgr-qchep-phPLB(2021)·30 citations
26. 26*

    Constraints on variation of fine structure constant from joint SPT-SZ and XMM-Newton observations

    Kamal Bora🇮🇳 · Shantanu Desai🇮🇳

    We search for a variation of the electromagnetic fine structure constant ($\alpha \equiv e^2/\hslash c$) using a sample of 58 SZ selected clusters in the redshift range ($0.2<z<1.5$) detected by the South Pole Telescope, along with X-ray measurements using the XMM-Newton observatory. We use the ratio of the integrated SZ Compto-ionization to its X-ray counterpart as our observable for this search. We first obtain a model-independent constraint on $\alpha$ of about 0.7%, using the fact that the aforementioned ratio is constant as a function of redshift. We then look for a logarithmic dependence of $\alpha$ as a function of redshift: $\Delta \alpha /\alpha =-\gamma \ln (1+z)$, as this is predicted by runaway dilaton models. We find that $\gamma$ = $-0.046\pm 0.1$, which indicates that there is no logarithmic variation of $\alpha$ as a function of redshift. We also search for a dipole variation of the fine structure constant using the same cluster sample. We do not find any evidence for such a spatial variation.

    ↳ astro-ph.COgr-qchep-phJCAP(2021)·36 citations
27. 27*

    Unpolarized and helicity generalized parton distributions of the proton within lattice QCD

    Constantia Alexandrou🇨🇾 · Krzysztof Cichy🇵🇱 · Martha Constantinou🇺🇸 · Kyriakos Hadjiyiannakou🇨🇾 · Karl Jansen🇩🇪 · Aurora Scapellato🇵🇱 · Fernanda Steffens🇩🇪

    We present the first calculation of the $x$-dependence of the proton generalized parton distributions (GPDs) within lattice QCD. Results are obtained for the isovector unpolarized and helicity GPDs. We compute the appropriate matrix elements of fast-moving protons coupled to non-local operators containing a Wilson line. We present results for proton momenta $0.83,1.25,1.67$ GeV, and momentum transfer squared $0.69,1.38$ GeV${}^2$. These combinations include cases with zero and nonzero skewness. The calculation is performed using one ensemble of two degenerate mass light, a strange and a charm quark of maximally twisted mass fermions with a clover term. The lattice results are matched to the light-cone GPDs using one-loop perturbation theory within the framework of large momentum effective theory. The final GPDs are given in the $\overline{\mathrm{MS}}$ scheme at a scale of 2 GeV.

    ↳ hep-lathep-exhep-phhep-thPRL(2020)·165 citations
28. 28*

    Analytic Structure of all Loop Banana Amplitudes

    Kilian Bönisch🇩🇪 · Fabian Fischbach🇩🇪 · Albrecht Klemm🇩🇪 · Christoph Nega🇩🇪 · Reza Safari🇩🇪

    Using the Gelfand-Kapranov-Zelevinsk\uı system for the primitive cohomology of an infinite series of complete intersection Calabi-Yau manifolds, whose dimension is the loop order minus one, we completely clarify the analytic structure of all banana amplitudes with arbitrary masses. In particular, we find that the leading logarithmic structure in the high energy regime, which corresponds to the point of maximal unipotent monodromy, is determined by a novel $\hat{\Gamma }$-class evaluation in the ambient spaces of the mirror, while the imaginary part of the amplitude in this regime is determined by the $\hat{\Gamma }$-class of the mirror Calabi-Yau manifold itself. We provide simple closed all loop formulas for the former as well as for the Frobenius $\kappa$-constants, which determine the behaviour of the amplitudes, when the momentum square equals the sum of the masses squared, in terms of zeta values. We extend our previous work from three to four loops by providing for the latter case a complete set of (inhomogenous) Picard-Fuchs differential equations for arbitrary masses. This allows to evaluate the amplitude as well as other master integrals with raised powers of the propagators in very short time to very high numerical precision for all values of the physical parameters. Using a recent $p$-adic analysis of the periods we determine the value of the maximal cut equal mass four-loop amplitude at the attractor points in terms of periods of modular weight two and four Hecke eigenforms and the quasiperiods of their meromorphic cousins.

    ↳ hep-thhep-phmath.AGmath.NTJHEP(2021)·111 citations

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