Thu·Dec 12, 2019Thursday·December 12, 2019

1. 01*

   Chemical freeze-out conditions from net-kaon fluctuations at RHIC

   Jamie M. Stafford🇺🇸

   We compare the mean-over-variance ratio of the net-kaon distribution calculated within a state-of-the-art hadron resonance gas model to the latest experimental data from the Beam Energy Scan at RHIC by the STAR collaboration. Our analysis indicates that it is not possible to reproduce the experimental results using the freeze-out parameters from the existing combined fit of net-proton and net-electric charge mean-over-variance. The strange mesons need about 10-15 MeV higher temperatures than the light hadrons at the highest collision energies. In view of the recent lambda fluctuation measurements, we predict the net-lambda variance-over-mean at the light and strange chemical freeze-out parameters. We observe that the lambda fluctuations are sensitive to the difference in the freeze-out temperatures established in this analysis. Our results have implications for other phenomenological models in the field of relativistic heavy-ion collisions.

   hep-phnucl-thJ.Phys.Conf.Ser.(2020)·0 citations
2. 02*

   Measurement of $D^0-{\bar{D}}^0$ mixing parameters using semileptonic decays of neutral kaon

   Pavel Pakhlov🇷🇺 · Vitaliy Popov🇷🇺

   We propose a new method to extract $D^0-{\bar{D}}^0$ mixing parameters using the $D^0\to \bar{K}{}^0{\pi }^0$ decay with the $\bar{K}{}^0$ reconstructed in the semileptonic mode. Although a $K^0\to {\pi }^{\pm }{l}^{\mp }{\nu }_l$ decay suffers from low statistics and complexity of the secondary vertex reconstruction in comparison to the standard $K_S\to {\pi }^{+}{\pi }^{-}$ vertex, it provides much richer, sometimes unique information about the initial state of a $K^0$-meson produced in a heavy-flavor hadron decay. In this paper it is shown that the reconstruction of the chain $D^0\to K^0({\pi }^{\pm }{l}^{\mp }{\nu }_l){\pi }^0$ allows one to extract the strong phase difference between the doubly Cabibbo-suppressed and Cabibbo-favored decay amplitudes, which is of key importance for determination of the $D^0-{\bar{D}}^0$ mixing parameters.

   hep-phJHEP(2020)·2 citations
3. 03*

   Strange quark stars within proper time regularized (2+1)-flavor NJL model

   Cheng-Ming Li🇨🇳 · Shu-Yu Zuo🇨🇳 · Yan Yan🇨🇳 · Ya-Peng Zhao🇨🇳 · Fei Wang🇨🇳 · Yong-Feng Huang🇨🇳 · Hong-Shi Zong🇨🇳

   In this work we use the equation of state (EOS) of (2+1)-flavor Nambu-Jona-Lasinio (NJL) model to study the structure of the strange quark star. With a new free parameter $\alpha$, the Lagrangian is constructed by two parts, the original NJL Lagrangian and the Fierz transformation of it, as $\mathcal{L}=(1-\alpha ){\mathcal{L}}_{NJL}+\alpha {\mathcal{L}}_{Fierz}$. To determine the range of $\alpha$, we compare the binding energies in the 2-flavor and (2+1)-flavor cases. We also consider the constraints of chemical equilibrium and electric charge neutrality in the strange quark star and choose six representative EOSs with different $\alpha$ and $B$ (bag constant) to study their influence on the structure of the strange quark star. As a result, we find that a larger $\alpha$ and a smaller $B$ corresponds to a heavier star with a stiffer EOS. Furthermore, the heaviest strange quark star is in agreement with not only the recent mass observation of PSR J0740+6620 and the X-ray observations on radius measurements, but also the constraint on tidal deformability of GW170817.

   hep-phnucl-thPRD(2020)·42 citations
4. 04*

   Differences in binarity between gluon and graviton scattering amplitudes

   Abhilash Mathews🇺🇸

   Both 3- and 4-point scattering amplitudes for spin-1 massless particles (gluons) and spin-2 massless particles (gravitons) are reviewed through self-contained step-by-step derivation. Gluon and graviton interactions are computed from on-shell diagrams by starting from complex momenta and introducing spinor-helicity formalism. By Fourier transforming spinor variables in momentum space, binarity is revealed in pure Yang-Mills scattering amplitudes while absent to a certain extent for gravity indicating fundamental differences in the probability spaces spanned by the two interactions.

   hep-ph0 citations
5. 05*

   Nucleon-to-meson transition distribution amplitudes in impact parameter space

   Bernard Pire🇫🇷 · Kirill Semenov-Tian-Shansky🇷🇺 · Lech Szymanowski🇵🇱

   Recent analyses of backward meson electroproduction support the validity of a collinear QCD factorization framework for these hard exclusive reactions. This opens a way to the extraction of nucleon-to-meson transition distribution amplitudes (TDAs) from the experimental data. Similarly to the generalized parton distributions, TDAs - after the Fourier transform in the transverse plane - carry valuable information on the transverse location of hadron constituents. We address the properties of integrated nucleon-to-meson TDAs in the impact parameter representation. We argue that the emerging picture provides an intuitive interpretation for the hadron structural information contained in nucleon-to-meson TDAs and allows to study diquark-quark contents of fast moving hadrons in the transverse plane.

   hep-phhep-exnucl-exnucl-thPoS(2019)·6 citations
6. 06*

   Effect of color reconnection on forward-backward multiplicity and mean transverse momentum correlation

   Sourav Kundu🇮🇳 · Bedangadas Mohanty🇮🇳 · Dukhishyam Mallick🇮🇳

   Color reconnection (CR) mechanism in PYTHIA model has been reported to be essential to describe the flow-like collective effect observed in high multiplicity $p$+$p$ and $p$+Pb collisions. In this work, we test this mechanism towards explaining the Forward-Backward multiplicity correlation (b${}_{\mathrm{cor}}$) measurements in $p$+$p$ collisions at the LHC energies. Out of the three different CR schemes implemented in PYTHIA, (a) MPI based CR (default mechanism), (b) QCD based CR and (c) Gluon moved CR, we found that the QCD based CR scheme describes relatively better the ALICE measurements of b${}_{\mathrm{cor}}$ in $p$+$p$ collisions at $\sqrt{\mathrm{s}}$ = 0.9 and 7 TeV. In addition, we have tuned the parameters of the default CR mechanism in PYTHIA to describe simultaneously the measured charged particle multiplicity pseudo-rapidity ($\eta$) distribution and b${}_{\mathrm{cor}}$. We found that an average number of multipartonic interactions ($⟨N_{\mathrm{MPI}}⟩$) between 2.5 to 3 and CR range between 0.9 to 2.5 best describes the experimental data. Finally, we have presented a study using PYTHIA events for $p$+$p$ collisions at $\sqrt{\mathrm{s}}$ = 7 TeV which shows that the strength of Forward-Backward mean transverse momentum correlation (b${}_{\mathrm{cor}}^{⟨p_{\mathrm{T}}⟩⟨p_{\mathrm{T}}⟩}$) is found to increase with CR in contrast to decrease of b${}_{\mathrm{cor}}$ values with CR effect. Hence, simultaneously studying the b${}_{\mathrm{cor}}^{⟨p_{\mathrm{T}}⟩⟨p_{\mathrm{T}}⟩}$ and b${}_{\mathrm{cor}}$ in the experiments will help in establishing the arguments either in favour or in disfavour of CR effect in the measurements.

   hep-phhep-exnucl-th8 citations
7. 07*

   Holographic thermalisation of strongly-coupled systems

   Floriana Giannuzzi🇮🇹

   The thermalisation of a strongly-coupled plasma is studied through the AdS/CFT correspondence. The system starts behaving as in viscous hydrodynamics shortly after the end of the perturbation. Local and nonlocal probes are used to characterise the process towards equilibrium.

   hep-ph0 citations
8. 08*

   NNLO QED contribution to the $\mu e\to \mu e$ elastic scattering

   Jonathan Ronca🇪🇸

   We present the current status of the Next-to-Next-to-Leading Order QED contribution to the $\mu e$-scattering. Particular focus is given to the techniques involved to tackle the virtual amplitude and their automatic implementation. Renormalization of the amplitude will be also discuss in details.

   hep-phEPJ Web Conf.(2020)·5 citations
9. 09*

   Robust Independent Validation of Experiment and Theory: Rivet version 3

   C. Bierlich🇸🇪 · A. Buckley🇬🇧 · J. M. Butterworth🇬🇧 · C. H. Christensen🇩🇰 · L. Corpe🇬🇧 · D. Grellscheid🇳🇴 · J. F. Grosse-Oetringhaus🇨🇭 · C. Gutschow🇬🇧 · P. Karczmarczyk🇨🇭 · J. Klein🇨🇭 · L. Lonnblad🇸🇪 · C. S. Pollard🇩🇪 and 3 other authors

   First released in 2010, the Rivet library forms an important repository for analysis code, facilitating comparisons between measurements of the final state in particle collisions and theoretical calculations of those final states. We give an overview of Rivet's current design and implementation, its uptake for analysis preservation and physics results, and summarise recent developments including propagation of MC systematic-uncertainty weights, heavy-ion and $ep$ physics, and systems for detector emulation. In addition, we provide a short user guide that supplements and updates the Rivet user manual.

   hep-phhep-exSciPost Phys.(2020)·425 citations
10. 10*

    Dirac vs. Majorana HNLs (and their oscillations) at SHiP

    Jean-Loup Tastet🇩🇰 · Inar Timiryasov🇨🇭

    SHiP is a proposed high-intensity beam dump experiment set to operate at the CERN SPS. It is expected to have an unprecedented sensitivity to a variety of models containing feebly interacting particles, such as Heavy Neutral Leptons (HNLs). Two HNLs or more could successfully explain the observed neutrino masses through the seesaw mechanism. If, in addition, they are quasi-degenerate, they could be responsible for the baryon asymmetry of the Universe. Depending on their mass splitting, HNLs can have very different phenomenologies: they can behave as Majorana fermions -- with lepton number violating (LNV) signatures, such as same-sign dilepton decays -- or as Dirac fermions with only lepton number conserving (LNC) signatures. In this work, we quantitatively demonstrate that LNV processes can be distinguished from LNC ones at SHiP, using only the angular distribution of the HNL decay products. Accounting for spin correlations in the simulation and using boosted decision trees for discrimination, we show that SHiP will be able to distinguish Majorana-like and Dirac-like HNLs in a significant fraction of the currently unconstrained parameter space. If the mass splitting is of order $10^{-6}$ eV, SHiP could even be capable of resolving HNL oscillations, thus providing a direct measurement of the mass splitting. This analysis highlights the potential of SHiP to not only search for feebly interacting particles, but also perform model selection.

    hep-phhep-exJHEP(2020)·55 citations
11. 11*

    Prospects for Detecting Boosted Dark Matter in DUNE through Hadronic Interactions

    Joshua Berger🇺🇸 · Yanou Cui🇺🇸 · Mathew Graham🇺🇸 · Lina Necib🇺🇸 · Gianluca Petrillo🇺🇸 · Dane Stocks🇺🇸 · Yun-Tse Tsai🇺🇸 · Yue Zhao🇺🇸

    Boosted dark matter (BDM) is a well-motivated class of dark matter (DM) candidates in which a small component of DM is relativistic at the present time. We lay the foundation for BDM searches via hadronic interactions in large liquid-argon time-projection chambers (LArTPCs), such as DUNE. We investigate BDM-nucleus scattering in detail by developing new event generation techniques with a parameterized detector simulation. We study the discovery potential in a DUNE-like experiment using the low threshold and directionality of hadron detection in LArTPCs and compare with other experiments.

    hep-phastro-ph.COhep-exPRD(2021)·49 citations
12. 12*

    Reduction of Feynman Integrals in the Parametric Representation II: Reduction of Tensor Integrals

    Wen Chen🇨🇦

    In a recent paper by the author (Chen in JHEP 02:115, 2020), the reduction of Feynman integrals in the parametric representation was considered. Tensor integrals were directly parametrized by using a generator method. The resulting parametric integrals were reduced by constructing and solving parametric integration-by-parts (IBP) identities. In this paper, we furthermore show that polynomial equations for the operators that generate tensor integrals can be derived. Based on these equations, two methods to reduce tensor integrals are developed. In the first method, by introducing some auxiliary parameters, tensor integrals are parametrized without shifting the spacetime dimension. The resulting parametric integrals can be reduced by using the standard IBP method. In the second method, tensor integrals are (partially) reduced by using the technique of Gröbner basis combined with the application of symbolic rules. The unreduced integrals can further be reduced by solving parametric IBP identities.

    hep-phEPJC(2021)·23 citations
13. 13*

    CMB distance priors revisited: effects of dark energy dynamics, spatial curvature, primordial power spectrum, and neutrino parameters

    Zhongxu Zhai🇺🇸 · Chan-Gyung Park🇰🇷 · Yun Wang🇺🇸 · Bharat Ratra🇺🇸

    As a physical and sufficient compression of the full CMB data, the CMB distance priors, or shift parameters, have been widely used and provide a convenient way to include CMB data when obtaining cosmological constraints. In this paper, we revisit this data vector and examine its stability under different cosmological models. We find that the CMB distance priors are an accurate substitute for the full CMB data when probing dark energy dynamics. This is true when the primordial power spectrum model is directly generalized from the power spectrum of the model used in the derivation of the distance priors from the CMB data. We discover a difference when a non-flat model with the untilted primordial inflation power spectrum is used to measure the distance priors. This power spectrum is a radical change from the more conventional tilted primordial power spectrum and violates fundamental assumptions for the reliability of the CMB shift parameters. We also investigate the performance of CMB distance priors when the sum of neutrino masses $\sum m_{\nu }$ and the effective number of relativistic species $N_{\text{eff}}$ are allowed to vary. Our findings are consistent with earlier results: the neutrino parameters can change the measurement of the sound horizon from CMB data, and thus the CMB distance priors. We find that when the neutrino model is allowed to vary, the cold dark matter density ${\omega }_c$ and $N_{\text{eff}}$ need to be included in the set of parameters that summarize CMB data, in order to reproduce the constraints from the full CMB data. We present an updated and expanded set of CMB distance priors which can reproduce constraints from the full CMB data within $1\sigma$, and are applicable to models with massive neutrinos, as well as non-standard cosmologies.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2020)·56 citations
14. 14*

    Gravitational Collider Physics

    Daniel Baumann🇳🇱 · Horng Sheng Chia🇳🇱 · Rafael A. Porto🇩🇪 · John Stout🇳🇱

    We study the imprints of new ultralight particles on the gravitational-wave signals emitted by binary black holes. Superradiant instabilities may create large clouds of scalar or vector fields around rotating black holes. The presence of a binary companion then induces transitions between different states of the cloud, which become resonantly enhanced when the orbital frequency matches the energy gap between the states. We find that the time dependence of the orbit significantly impacts the cloud's dynamics during a transition. Following an analogy with particle colliders, we introduce an S-matrix formalism to describe the evolution through multiple resonances. We show that the state of the cloud, as it approaches the merger, carries vital information about its spectrum via time-dependent finite-size effects. Moreover, due to the transfer of energy and angular momentum between the cloud and the orbit, a dephasing of the gravitational-wave signal can occur which is correlated with the positions of the resonances. Notably, for intermediate and extreme mass ratio inspirals, long-lived floating orbits are possible, as well as kicks that yield large eccentricities. Observing these effects, through the precise reconstruction of waveforms, has the potential to unravel the internal structure of the boson clouds, ultimately probing the masses and spins of new particles.

    ↳ gr-qchep-phhep-thPRD(2020)·169 citations
15. 15*

    Drag Force in the Vacuum of Confining Gauge Theories

    Saulo Diles🇧🇷 · Miguel Angel Martin Contreras🇨🇱 · Alfredo Vega🇨🇱

    The complete absence of isolated quarks reaching particle detectors after high energy collisions suggests that some physical mechanism generates resistance to their propagation in the vacuum. In order to reveal such a mechanism, we analyze the fate of an infinitely heavy quark that is initially propagating in the vacuum with inertial motion. The non-perturbative structure of the vacuum is treated here using the gauge/ gravity correspondence, the isolated quark on the boundary gauge theory is dual to a trailing string moving in the bulk of a higher dimensional curved space. We find that, for a large class of non-conformal gauge theories with a holographic dual, the geometrical structure of the bulk geometry induces a drag force on the quark that moves in the vacuum. In addition, we show that for these gauge theories there will be the presence of such a drag force due to its vacuum whenever the dual bulk geometry generates a linear potential for a $q\bar{q}$ pair. The relation of the linear $q\bar{q}$ potential with the drag force on the isolated quark is a holographic piece of evidence that both phenomena are different manifestations of the confinement of quarks.

    ↳ hep-thhep-phNPB(2022)·4 citations
16. 16*

    Calculated solar-neutrino capture rate for a radiochemical 205 Tl-based solar-neutrino detector

    Joel Kostensalo🇫🇮 · Jouni Suhonen🇫🇮 · Kai Zuber🇩🇪

    Radiochemical experiments for low-energy solar-neutrino detection have been making headlines by exploiting the isotopes \iso{Cl}{37} and \iso{Ga}{71}. Such a very low-threshold measurement of this type can also be performed using \iso{Tl}{205}, which has been considered for decades for this purpose. A unique feature of this detector nucleus is the integration is the solar-neutrino flux over millions of years owing to its long-living daughter \iso{Pb}{205}. In this study we have calculated for the first time the cross section for the charged-current solar-neutrino scattering off \iso{Tl}{205}. Taking into account the solar-model-predicted neutrino fluxes and the electron-neutrino survival probabilities, a solar-neutrino capture rate of 62.2 $\pm 8.6$ SNU is determined, a value significantly smaller than in previous estimates.

    ↳ nucl-thhep-phPRC(2020)·7 citations
17. 17*

    A High Efficiency Photon Veto for the Light Dark Matter eXperiment

    Torsten Åkesson · Nikita Blinov · Lene Bryngemark · Owen Colegrove · Giulia Collura · Craig Dukes. Valentina Dutta · Bertrand Echenard · Thomas Eichlersmith · Craig Group · Joshua Hiltbrand · David G. Hitlin · Joseph Incandela and 19 other authors

    Fixed-target experiments using primary electron beams can be powerful discovery tools for light dark matter in the sub-GeV mass range. The Light Dark Matter eXperiment (LDMX) is designed to measure missing momentum in high-rate electron fixed-target reactions with beam energies of 4 GeV to 16 GeV. A prerequisite for achieving several important sensitivity milestones is the capability to efficiently reject backgrounds associated with few-GeV bremsstrahlung, by twelve orders of magnitude, while maintaining high efficiency for signal. The primary challenge arises from events with photo-nuclear reactions faking the missing-momentum property of a dark matter signal. We present a methodology developed for the LDMX detector concept that is capable of the required rejection. By employing a detailed GEANT4-based model of the detector response, we demonstrate that the sampling calorimetry proposed for LDMX can achieve better than $10^{-13}$ rejection of few-GeV photons. This suggests that the luminosity-limited sensitivity of LDMX can be realized at 4 GeV and higher beam energies.

    ↳ physics.ins-dethep-exhep-phJHEP(2020)·32 citations
18. 18*

    Yangian Bootstrap for Conformal Feynman Integrals

    Florian Loebbert🇩🇪 · Dennis Müller🇩🇰 · Hagen Münkler🇨🇭

    We explore the idea to bootstrap Feynman integrals using integrability. In particular, we put the recently discovered Yangian symmetry of conformal Feynman integrals to work. As a prototypical example we demonstrate that the D-dimensional box integral with generic propagator powers is completely fixed by its symmetries to be a particular linear combination of Appell hypergeometric functions. In this context the Bloch-Wigner function arises as a special Yangian invariant in 4D. The bootstrap procedure for the box integral is naturally structured in algorithmic form. We then discuss the Yangian constraints for the six-point double box integral as well as for the related hexagon. For the latter we argue that the constraints are solved by a set of generalized Lauricella functions and we comment on complications in identifying the integral as a certain linear combination of these. Finally, we elaborate on the close relation to the Mellin-Barnes technique and argue that it generates Yangian invariants as sums of residues.

    ↳ hep-thhep-phmath-phmath.MPPRD(2020)·66 citations
19. 19*

    Light Dark Matter: A Common Solution to the Lithium and $H_0$ Problems

    Jailson Alcaniz🇧🇷 · Nicolás Bernal🇨🇴 · Antonio Masiero🇮🇹 · Farinaldo S. Queiroz🇧🇷

    Currently, the standard cosmological model faces some tensions and discrepancies between observations at early and late cosmological time. One of them concerns the well-known $H_0$-tension problem, i.e., a $\sim 4.4\sigma$-difference between the early-time estimate and late-time measurements of the Hubble constant, $H_0$. Another puzzling question rests in the cosmological lithium abundance, where again local measurements differ from the one predicted by Big Bang Nucleosynthesis (BBN). In this work, we show that a mechanism of light dark matter production might hold the answer for these questions. If dark matter particles are sufficiently light and a fraction of them was produced non-thermally in association with photons, this mechanism has precisely what is needed to destroy Lithium without spoiling other BBN predictions. Besides, it produces enough radiation that leads to a larger $H_0$ value, reconciling early and late-time measurements of the Hubble expansion rate without leaving sizable spectral distortions in the Cosmic Microwave Background spectrum.

    ↳ astro-ph.COhep-phPLB(2021)·58 citations
20. 20*

    Holographic computation of Wilson loops in a background with broken conformal invariance and finite chemical potential

    Ashis Saha🇮🇳 · Sunandan Gangopadhyay🇮🇳

    In this paper, we follow a `bottom-up' AdS/QCD approach to holographically probe the dynamics of a moving $q\bar{q}$ pair inside a strongly coupled plasma at the boundary. We consider a deformed AdS-Reissner Nordström metric in the bulk in order to introduce nonconformality and finite quark density in the dual field theory. By boosting the gravity solution in a specific direction we consider two extreme cases of orientation, parallel and perpendicular, for the Wilson loop which in turn fixes the relative position of the $q\bar{q}$ pair with respect to the direction of boost in the plasma. By utilizing this set-up, we holographically compute the vacuum expectation value of the time-like Wilson loop in order to obtain real part of the $q\bar{q}$ potential and the effects of nonconformality (deformation parameter $c$), chemical potential $\mu$ and rapidity $\beta$ are observed on this potential. We then compute the in-medium energy loss of the moving parton (jet quenching parameter $q_m$) by setting $\beta \to \infty$ which in turn makes the Wilson loop light-like. We also use the jet quenching as an order parameter to probe the strongly-coupled domain of the dual field theory. Finally, we compute the imaginary part of the $q\bar{q}$ potential ($\mathrm{Im}(V_{q\bar{q}})$) by considering the thermal fluctuation (arbitrary long wavelength) of the string world-sheet. It is observed that for fixed values of the chemical potential and rapidity, increase in the nonconformality parameter leads to an increase in the real and imaginary potentials as well as the jet quenching parameter.

    ↳ hep-thhep-phPRD(2020)·6 citations
21. 21*

    Describing Migdal effects in diamond crystal with atom-centered localized Wannier functions

    Zheng-Liang Liang🇨🇳 · Lin Zhang🇨🇳 · Fawei Zheng🇨🇳 · Ping Zhang🇨🇳

    Recent studies have theoretically investigated the atomic excitation and ionization induced by the dark matter (DM)-nucleus scattering, and it is found that the suddenly recoiled atom is much more likely to excite or lose its electrons than expected. Such phenomenon is called the "Migdal effect". In this paper, we extend the established strategy to describe the Migdal effect in isolated atoms to the case in semiconductors under the framework of tight-binding (TB) approximation. Since the localized aspects of electrons are respected in form of the Wannier functions (WFs), the extension of the existing Migdal approach for isolated atoms is much more natural, while the extensive nature of electrons in solids is reflected in the hopping integrals. We take diamond target as a concrete proof of principle for the methodology, and calculate relevant energy spectra and projected sensitivity of such diamond detector. It turns out that our method as a preliminary attempt is practically effective.

    ↳ cond-mat.mes-hallhep-phnucl-thPRD(2020)·28 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.