Wed·Apr 8, 2020Wednesday·April 8, 2020

1. 01*

   Quadrupole pressure and shear forces inside baryons in the large $N_c$ limit

   Julia Yu. Panteleeva🇩🇪 · Maxim V. Polyakov🇩🇪

   We derive number of relations between quadrupole energy, elastic pressure, and shear force distributions in baryons using the large $N_c$ picture of baryons as chiral solitons. The obtained large $N_c$ relations are independent of particular dynamics and should hold in any picture in which the baryon is the chiral soliton. One of remarkable qualitative predictions of the soliton picture is the nullification of the tangential forces acting on the radial area element for any tensor polarisation of the baryon. The derived relations provide a powerful tool to check the hypothesis that the baryons are chiral solitons, say using lattice QCD.

   hep-phhep-exhep-latPLB(2020)·31 citations
2. 02*

   On the possible virtual state nature of the LHCb Pc$(4312{)}^{+}$ signal

   Jorge A. Silva-Castro🇲🇽

   In this contribution we study the nature of the new Pc$(4312{)}^{+}$ signal reported by LHCb collaboration in the $J/\psi p$ spectrum. We use $S$-matrix principles to perform a minimum-bias analysis of the data, focusing on the analytic properties that can be related to the microscopic origin of the Pc$(4312{)}^{+}$ peak. Using the scattering length approximation we find evidence for interpretation of the signal as a virtual state generated by the attractive effect of the ${\Sigma }_c^{+}{\bar{D}}^0$ channel opening.

   hep-phJ.Phys.Conf.Ser.(2020)·1 citation
3. 03*

   Dark matter and Standard Model reheating from conformal GUT inflation

   Simone Biondini🇳🇱 · K. Sravan Kumar🇳🇱

   Spontaneous breaking of conformal symmetry has been widely exploited in successful model building of both inflationary cosmology and particle physics phenomenology. Conformal Grand Unified Theory (CGUT) inflation provides the same scalar tilt and tensor-to-scalar ratio as of Starobinsky and Higgs inflation. Moreover, it predicts a proton life time compatible with the current experimental bound. In this paper, we extend CGUT to account for the production of dark matter and the reheating of the Standard Model. To this end, we introduce a hidden sector directly coupled to the inflaton, whereas the reheating of the visible sector is realized through a portal coupling between the dark particles and the Higgs boson. The masses and interactions of the dark particles and the Higgs boson are determined by the form of the conformal potential and the non-vanishing VEV of the inflaton. We provide benchmark points in the parameter space of the model that give the observed dark matter relic density and reheating temperatures compatible with the Big Bang nucleosynthesis.

   hep-phastro-ph.COhep-thJHEP(2020)·8 citations
4. 04*

   Model Independent Extraction of the Proton Charge Radius from PRad data

   Gil Paz🇺🇸

   The proton radius puzzle has motivated several new experiments that aim to extract the proton charge radius and resolve the puzzle. Recently PRad, a new electron-proton scattering experiment at Jefferson Lab, reported a proton charge radius of $0.831\pm 0.007_{\text{statistical}}\pm 0.012_{\text{systematic}}$. The value was obtained by using a rational function model for the proton electric form factor. We perform a model-independent extraction using $z$-expansion of the proton charge radius from PRad data. We find that the model-independent statistical error is more than 50\% larger compared to the statistical error reported by PRad.

   hep-phhep-exnucl-exnucl-thMod.Phys.Lett.A(2021)·7 citations
5. 05*

   Top quark pair production near threshold: single/double distributions and mass determination

   Wan-Li Ju🇬🇧 · Guoxing Wang🇨🇳 · Xing Wang🇩🇪 · Xiaofeng Xu🇨🇭 · Yongqi Xu🇨🇳 · Li Lin Yang🇨🇳

   We investigate top quark pair production near the threshold where the pair invariant mass $M_{t\bar{t}}$ approaches $2m_t$, which provides sensitive observables to extract the top quark mass $m_t$. Using the effective field theory methods, we derive a factorization and resummation formula for kinematic distributions in the threshold limit up to the next-to-leading power, which resums higher order Coulomb corrections to all orders in the strong coupling constant. Our formula is similar to those in the literature but differs in several important aspects. We apply our formula to the $M_{t\bar{t}}$ distribution, as well as to the double differential cross section with respect to $M_{t\bar{t}}$ and the rapidity of the $t\bar{t}$ pair. We find that the resummation effects significantly increase the cross sections near the threshold, and lead to predictions better compatible with experimental data than the fixed-order ones. We demonstrate that incorporating resummation effects in the top quark mass determination can shift the extracted value of $m_t$ by as large as 1.4 GeV. The shift is much larger than the estimated uncertainties in previous experimental studies, and leads to a value of the top quark pole mass more consistent with the current world average.

   hep-phhep-exJHEP(2020)·58 citations
6. 06*

   Probing new physics scenarios of muon $g-2$ via $J/\psi$ decay at BESIII

   Gorazd Cvetič🇨🇱 · C.S. Kim🇰🇷 · Donghun Lee🇰🇷 · Dibyakrupa Sahoo🇰🇷

   The disagreement between the standard model prediction and the experimental measurement of muon anomalous magnetic moment can be alleviated by invoking an additional particle which is either a vector boson ($X_1$) or a scalar ($X_0$). This new particle, with the mass $m_X\lesssim 2m_{\mu }$, can be searched for in the decay $J/\psi \to {\mu }^{-}{\mu }^{+}X$, where $X$ is missing. Our numerical study shows that the search is quite feasible at the BESIII experiment in the parameter space allowed by muon $g-2$ measurements.

   hep-phJHEP(2020)·9 citations
7. 07*

   Significance of broken $\mu -\tau$ Symmetry in correlating ${\delta }_{CP}$, ${\theta }_{13}$, Lightest neutrino Mass and neutrinoless double beta decay $0\nu \beta \beta$

   Gayatri Ghosh🇮🇳

   Leptonic CP Violating Phase ${\delta }_{CP}$ in the light neutrino sector and leptogenesis via present matter antimatter asymmetry of the Universe entails each other. Probing CP violation in light neutrino oscillation is one of the challenging tasks today. The reactor mixing angle ${\theta }_{13}$ measured in reactor experiments, LBL, DUNE with high precision in neutrino experiments indicates towards the vast dimension of scope to detect ${\delta }_{CP}$. The correlation between leptonic Dirac CPV phase ${\delta }_{CP}$, reactor mixing angle ${\theta }_{13}$, lightest neutrino mass $m_1$ and matter antimatter asymmetry of the Universe within the framework of $\mu -\tau$ symmetry breaking assuming the type I seesaw dominance is extensively studied here. Small tiny breaking of the $\mu -\tau$ symmetry allows a large Dirac CP violating phase in neutrino oscillation which in turn is characterised by awareness of measured value of ${\theta }_{13}$ and to provide a hint towards a better understanding of the experimentally observed near maximal value of ${\nu }_{\mu }-{\nu }_{\tau }$ mixing angle ${\theta }_{23}\simeq \frac{\pi }{4}$. Precise breaking of the $\mu -\tau$ symmetry is achieved by adding a 120 plet Higgs to the 10 $+$ $\overline{126}$ dimensional representation of Higgs. The estimated three dimensional density parameter space of lightest neutrino mass $m_1$, ${\delta }_{CP}$, reactor mixing angle ${\theta }_{13}$, is constrained here for the requirement of producing the observed value of baryon asymmetry of the Universe through the mechanism of leptogenesis. Carrying out numerical analysis the allowed parameter space of $m_1$, ${\delta }_{CP}$, ${\theta }_{13}$, is found out which can produce the observed baryon to photon density ratio of the Universe.

   hep-phAdv.High Energy Phys.(2021)·4 citations
8. 08*

   Study on the possible molecular state composed of $D_s^{\ast }{\bar{D}}_{s1}$ within the Bethe-Salpeter framework

   Hong-Wei Ke🇨🇳 · Xiao-Hai Liu🇨🇳 · Xue-Qian Li🇨🇳

   Recently a vector charmonium-like state $Y(4626)$ was observed in the portal of $D_s^{+}{D}_{s1}(2536{)}^{-}$. It intrigues an active discussion on the structure of the resonance because it has obvious significance for gaining a better understanding on its hadronic structure with suitable inner constituents. It indeed concerns the general theoretical framework about possible structures of exotic states. Since the mass of $Y(4626)$ is slightly above the production threshold of $D_s^{+}{\bar{D}}_{s1}(2536{)}^{-}$ whereas below that of $D_s^{\ast }{\bar{D}}_{s1}(2536)$ with the same quark contents as that of $D_s^{+}{\bar{D}}_{s1}(2536{)}^{-}$, it is natural to conjecture $Y(4626)$ to be a molecular state of $D_s^{\ast }{\bar{D}}_{s1}(2536)$, as suggested in literature. Confirming or negating this allegation would shed light on the goal we concern. We calculate the mass spectrum of a system composed of a vector meson and an axial vector i.e. $D_s^{\ast }{\bar{D}}_{s1}(2536)$ within the framework of the Bethe-Salpeter equations. Our numerical results show that the dimensionless parameter $\lambda$ in the form factor which is phenomenologically introduced to every vertex, is far beyond the reasonable range for inducing an even very small binding energy $\Delta E$. It implies that the $D_s^{\ast }{\bar{D}}_{s1}(2536)$ system cannot exist in the nature as a hadronic molecule in this model, so that we may not think the resonance $Y(4626)$ to be a bound state of $D_s^{\ast }{\bar{D}}_{s1}(2536)$, but something else, for example a tetraquark and etc.

   hep-phhep-exCPC(2020)·10 citations
9. 09*

   Hypergeometric presentation for one-loop contributing to $H\to Z\gamma$

   Khiem Hong Phan🇻🇳 · Dzung Tri Tran🇻🇳

   In this paper, new analytic formulas for one-loop contributing to Higgs decay channel $H\to Z\gamma$ are presented in terms of hypergeometric functions. The calculations are performed by following the technique for tensor one-loop reduction developed in [A.~I.~Davydychev, Phys.\ Lett.\ B {\bf 263} (1991) 107]. For the first time, one-loop form factors for the decay process are shown which are valid at arbitrary space-time dimension $d$.

   hep-phPTEP(2020)·2 citations
10. 10*

    ${\chi }_{c1}$ and ${\chi }_{c2}$ polarization as a probe of color octet channel

    S.P. Baranov🇷🇺 · A.V. Lipatov🇷🇺

    We analyze the first LHC data on ${\chi }_{c1}$ and ${\chi }_{c2}$ polarization obtained very recently by the CMS Collaboration at $\sqrt{s}=8$~TeV. We describe the perturbative production of $c\bar{c}$ pair with $k_T$-factorization approach and use nonrelativistic QCD formalism for the formation of bound states. We demonstrate that the polar anisotropy of ${\chi }_{c1}$ and ${\chi }_{c2}$ mesons is strongly sensitive to the color octet contributions. We extract the long-distance matrix elements for ${\chi }_{c1}$ and ${\chi }_{c2}$ mesons from the first CMS polarization measurement %on the polarization parameters ${\lambda }_{\theta }^{{\chi }_{c1}}$ and ${\lambda }_{\theta }^{{\chi }_{c2}}$ obtained at $\sqrt{s}=8$~TeV together with available LHC data on the ${\chi }_{c1}$ and ${\chi }_{c2}$ transverse momentum distributions (and their ratios) collected at $\sqrt{s}=7$~TeV. Our fit points to unequal color singlet wave functions of ${\chi }_{c1}$ and ${\chi }_{c2}$ states.

    hep-phEPJC(2020)·4 citations
11. 11*

    Understanding the newly observed ${\Xi }_c^0$ states through their decays

    Kai-Lei Wang🇨🇳 · Li-Ye Xiao🇨🇳 · Xian-Hui Zhong🇨🇳

    Inspired by the newly observed ${\Xi }_c^0$ states by the LHCb Collaboration, we investigate the OZI-allowed two-body strong decays of the $\lambda$-mode $1P$ wave ${\Xi }_c^{\prime }$ states within the chiral quark model. Our results indicate that: (i) the newly observed states ${\Xi }_c(2923{)}^0$ and ${\Xi }_c(2939{)}^0$ are good candidates of the $\lambda$-mode $1P$ wave ${\Xi }_c^{\prime }$ states with the spin-parity $J^P=3/2^{-}$, namely ${|}^4{P}_{\lambda }3/2^{-}⟩$ and ${|}^2{P}_{\lambda }3/2^{-}⟩$, respectively. (ii) The another newly observed state ${\Xi }_c(2965{)}^0$ mostly corresponds to the $\lambda$-mode $1P$-wave ${\Xi }_c^{\prime }$ state with the spin-parity $J^P=5/2^{-}$, namely ${|}^4{P}_{\lambda }5/2^{-}⟩$. (iii) For the two $\lambda$-mode $J^P=1/2^{-}$ mixed states, the $|P_{\lambda }1/2^{-}{⟩}_1$ is a narrow state with a width of $\Gamma \sim 15$ MeV and mainly decays into ${\Xi }_c^{\prime }\pi$; while the $|P_{\lambda }1/2^{-}{⟩}_2$ state has a width of $\Gamma \sim 52$ MeV and dominantly decays into ${\Xi }_c\pi$ and ${\Lambda }_{c}K$ channels. If the broad structure around $2880$ MeV observed at LHCb arises from the new ${\Xi }_c^0$ state, this state is very likely to be the $|P_{\lambda }1/2^{-}{⟩}_2$ state.

    hep-phPRD(2020)·35 citations
12. 12*

    NNLO zero-jettiness beam and soft functions to higher orders in the dimensional-regularization parameter $ϵ$

    Daniel Baranowski🇩🇪

    We present the calculation of the next-to-next-to-leading order (NNLO) zero-jettiness beam and soft functions, up to the second order in the expansion in the dimensional regularization parameter $ϵ$. These higher order terms are needed for the computation of the next-to-next-to-next-to-leading order (N${}^3$LO) zero-jettiness soft and beam functions. As a byproduct, we confirm the $O({ϵ}^0)$ results for NNLO beam and soft functions available in the literature.

    hep-phEPJC(2020)·26 citations
13. 13*

    Dark Matter in scalar Sp(N) gauge dynamics

    Giacomo Landini🇮🇹 · Jin-Wei Wang🇮🇹

    We consider a model with Sp dark gauge group and a scalar field in the fundamental representation, which leads to two co-stable DM candidates at the perturbative level thanks to a global U(1) accidental symmetry. After gauge confinement at low energy scale, only one of the two candidates is still stable. We compute the DM relic abundance by solving the Boltzmann equations numerically. The presence of light dark glueballs gives extra cosmological effects and can affect Higgs physics. We study the DM phenomenology, providing the predictions for direct and indirect detection (including the Sommerfeld enhancement). We show that the model predicts a slightly suppressed indirect detection cross section in comparison to the usual WIMPs paradigm.

    hep-phJHEP(2020)·8 citations
14. 14*

    Implementation of target mass corrections and higher-twist effects in the xFitter framework

    Muhammad Goharipour🇮🇷 · S. Rostami🇮🇷

    Knowledge of parton distribution functions (PDFs) at large momentum fraction $x$ is not only important to study the flavor and spin dynamics of quarks in the nucleon, but also to search for signals of new physics at collider experiments. It is well known now that the nonperturbative QCD effects generally play a more significant role at such kinematic regions. In this work, we present an open-source QCD analysis of PDFs considering target mass corrections (TMCs) and higher-twist (HT) effects which are necessary when the analysis includes also data points from deep inelastic scattering (DIS) with larger values of $x$ and smaller values of photon virtuality $Q^2$. To this aim, we use the xFitter package, as a comprehensive and powerful tool for studying PDFs. We report and discuss our recent activities on the implementation of TMCs and HT effects in the xFitter framework in a user-friendly way, so that the user can switch on or off them, and also choose between different options. We check the validity of the modifications by performing sample analyses of PDFs considering TMCs and HT effects and using a wide range of DIS data.

    hep-phhep-exPRD(2020)·5 citations
15. 15*

    Gravitational misalignment mechanism of Dark Matter production

    Eugeny Babichev🇫🇷 · Dmitry Gorbunov🇷🇺 · Sabir Ramazanov🇨🇿

    We consider Dark Matter composed of an oscillating singlet scalar field. On top of the mass term, the scalar is equipped with a potential spontaneously breaking Z_2-symmetry. This potential dominates at early times and leads to the time-dependent expectation value of the scalar, which decreases in the expanding Universe. As it drops below some critical value, the symmetry gets restored, and the Dark Matter field starts to oscillate around zero. We arrange the spontaneous symmetry breaking through the interaction of the scalar with the Ricci curvature. In that way, superheavy Dark Matter can be produced at very early times. Depending on its mass, the production takes place at inflation (very large masses up to the Grand Unification scale), at preheating, or at radiation-dominated stage (masses 10^{6}-10^{7} Gev).

    hep-phastro-ph.COhep-thJCAP(2020)·19 citations
16. 16*

    Heavy quarkonia in a bulk viscous medium

    Lata Thakur🇰🇷 · Najmul Haque🇮🇳 · Yuji Hirono🇰🇷

    We study the properties of heavy quarkonia in a quark-gluon plasma in the presence of bulk viscous effects. Within the hard thermal loop approximation at one-loop, the dielectric permittivity of quark-gluon plasma is computed, where the bulk viscous effect enters through the deformation of the distribution functions of thermal quarks and gluons. Based on the modified dielectric permittivity, we compute the in-medium heavy quark potential, that includes non-pertubative string-like terms as well as the perturbative Coulombic term. We discuss how the bulk viscous effect modifies the real and imaginary parts of the in-medium potential. Several prescriptions are examined as to how to include the string-like non-perturbative potentials. Using the deformed potential, we compute the wave functions, binding energies, and decay widths of heavy quarkonia in a bulk viscous medium, and study their sensitivity to the strength of the bulk viscous effect. An estimate of the melting temperatures is given.

    hep-phnucl-thJHEP(2020)·31 citations
17. 17*

    Measuring the Higgs self-coupling via Higgs-pair production at a 100 TeV p-p collider

    Michelangelo Mangano🇨🇭 · Giacomo Ortona🇮🇹 · Michele Selvaggi🇨🇭

    Higgs pair production provides a unique handle for measuring the strength of the Higgs self interaction and constraining the shape of the Higgs potential. Among the proposed future facilities, a circular 100 TeV proton-proton collider would provide the most precise measurement of this crucial quantity. In this work, we perform a detailed analysis of the most promising decay channels and derive the expected sensitivity of their combination, assuming an integrated luminosity of 30 ab${}^{-1}$. Depending on the assumed systematic uncertainties, we observe that the Higgs self-coupling will be measured with a precision in the range 3.4 - 7.8% at 68% confidence level.

    hep-phhep-exEPJC(2020)·65 citations
18. 18*

    Large-Momentum Effective Theory

    Xiangdong Ji🇺🇸 · Yu-Sheng Liu🇨🇳 · Yizhuang Liu🇨🇳 · Jian-Hui Zhang🇨🇳 · Yong Zhao🇺🇸

    Since the parton model was introduced by Feynman more than fifty years ago, we have learned much about the partonic structure of the proton through a large body of high-energy experimental data and dedicated global fits. However, calculating the partonic observables such as parton distribution function (PDFs) from the fundamental theory of strong interactions, QCD, has made limited progress. Recently, the authors have advocated a formalism, large-momentum effective theory (LaMET), through which one can extract parton physics from the properties of the proton travelling at a moderate boost-factor, e.g., $\gamma \sim (2-5)$. The key observation behind this approach is that Lorentz symmetry allows the standard formalism of partons in terms of light-front operators to be replaced by an equivalent one with large-momentum states and time-independent operators of a universality class. With LaMET, the PDFs, generalized PDFs or GPDs, transverse-momentum-dependent PDFs, and light-front wave functions can all be extracted in principle from lattice simulations of QCD (or other non-perturbative methods) through standard effective field theory matching and running. Future lattice QCD calculations with exa-scale computational facilities can help to understand the experimental data related to the hadronic structure, including those from the upcoming Electron-Ion Colliders dedicated to exploring the partonic landscape of the proton. Here we review the progress made in the past few years in development of the LaMET formalism and its applications, particularly on the demonstration of its effectiveness from initial lattice QCD simulations.

    hep-phhep-latnucl-thRMP(2021)·382 citations
19. 19*

    Non-perturbative renormalization scheme for the CP-odd three-gluon operator

    Vincenzo Cirigliano🇺🇸 · Emanuele Mereghetti🇺🇸 · Peter Stoffer🇺🇸

    We define a regularization-independent momentum-subtraction scheme for the $CP$-odd three-gluon operator at dimension six. This operator appears in effective field theories for heavy physics beyond the Standard Model, describing the indirect effect of new sources of $CP$-violation at low energies. In a hadronic context, it induces permanent electric dipole moments. The hadronic matrix elements of the three-gluon operator are non-perturbative objects that should ideally be evaluated with lattice QCD. We define a non-perturbative renormalization scheme that can be implemented on the lattice and we compute the scheme transformation to $\overline{\text{MS}}$ at one loop. Our calculation can be used as an interface to future lattice-QCD calculations of the matrix elements of the three-gluon operator, in order to obtain theoretically robust constraints on physics beyond the Standard Model from measurements of the neutron electric dipole moment.

    hep-phhep-exhep-latnucl-thJHEP(2020)·28 citations
20. 20*

    Light Quark Mediated Higgs Boson Threshold Production in the Next-to-Leading Logarithmic Approximation

    Charalampos Anastasiou🇨🇭 · Alexander Penin🇨🇦

    We study the amplitude of the Higgs boson production in gluon fusion mediated by a light quark loop and evaluate the logarithmically enhanced radiative corrections to the next-to-leading logarithmic approximation which sums up the terms of the form ${\alpha }_s^n{\ln }^{2n-1}(m_H/m_q)$ to all orders in the strong coupling constant. This result is used for the calculation of the process cross section near the production threshold and gives a quantitative estimate of the three and four-loop bottom quark contribution to the Higgs boson production at the Large Hadron Collider.

    hep-phhep-thJHEP(2020)·39 citations
21. 21*

    Post-inflationary axion isocurvature perturbations facing CMB and large-scale structure

    Martin Feix🇩🇪 · Steffen Hagstotz🇸🇪 · Andreas Pargner🇩🇪 · Robert Reischke🇮🇱 · Bjoern Malte Schaefer🇩🇪 · Thomas Schwetz🇩🇪

    Dark matter comprised of axion-like particles (ALPs) generated by the realignment mechanism in the post-inflationary scenario leads to primordial isocurvature fluctuations. The power spectrum of these fluctuations is flat for small wave numbers, extending to scales accessible with cosmological surveys. We use the latest measurements of Cosmic Microwave Background (CMB) primary anisotropies together with CMB lensing, Baryonic Acoustic Oscillations (BAO) and Sunyaev Zel'dovich (SZ) cluster counts to measure the amplitude and tilt of the isocurvature component. We find preference for a white-noise isocurvature component in the CMB primary anisotropies; this conclusion is, however, weakened by current large-scale structure (LSS) data. Interpreting the result as a conservative upper limit on the isocurvature component, the combined bound on the ALP mass from all probes is $m_a\gtrsim 10^{-19}$ eV, with some dependence on how $m_a$ evolves with temperature. The expected sensitivity of cosmic shear and galaxy clustering from future LSS experiments and CMB lensing suggests improved bounds of $m_a\gtrsim 10^{-18}$-$10^{-13}$ eV, depending on scale cuts used to avoid non-linearities and the ALP mass-temperature dependence.

    ↳ astro-ph.COhep-phJCAP(2020)·32 citations
22. 22*

    High-Energy Phase Diagrams with Charge and Isospin Axes under Heavy-Ion Collision and Stellar Conditions

    K. Aryal🇺🇸 · C. Constantinou🇺🇸 · R. L. S. Farias🇧🇷 · V. Dexheimer🇺🇸

    We investigate the phase transition from hadron to quark matter in the general case without the assumption of chemical equilibrium. The effects of net strangeness on charge and isospin fractions, chemical potentials, and temperature are studied in the context of the Chiral Mean Field (CMF) model that incorporates chiral symmetry restoration and deconfinement. The extent to which these quantities are probed during deconfinement in conditions expected to exist in protoneutron stars, binary neutron-star mergers, and heavy-ion collisions is analyzed via the construction of 3-dimensional phase diagrams.

    ↳ nucl-thastro-ph.HEastro-ph.SRhep-phPRD(2020)·35 citations
23. 23*

    The Non-perturbative Interaction of the Pseudovector Coupling for the Pion-nucleon Scattering

    Susumu Kinpara🇯🇵

    The effect of the non-perturbative term is investigated for the pion-nucleon scattering. Including the self-energy of nucleon the cross section of the elastic scattering results in a constant value at the laboratory momentum $p_L\to \infty$. The amplitude of the forward direction is applied to the dispersion relation.

    ↳ nucl-thhep-ph1 citation
24. 24*

    Seebeck effect in a thermal QCD medium in the presence of strong magnetic field

    Debarshi Dey🇮🇳 · Binoy Krishna Patra🇮🇳

    The strongly interacting partonic medium created post ultrarelativistic heavy ion collision experiments exhibits a significant temperature-gradient between the central and peripheral regions of the collisions, which in turn, is capable of inducing an electric field in the medium; a phenomenon known as Seebeck effect. The effect is quantified by the magnitude of the induced electric field per unit temperature-gradient - the Seebeck coefficient ($S$). We study the coefficient, $S$ in the relativistic Boltzmann transport equation in relaxation-time approximation, as a function of temperature ($T$) and chemical potential ($\mu$), wherein we find that with current quark masses, the magnitude of $S$ for individual flavours as well as that for the medium as a whole decreases with $T$ and increases with $\mu$, with the electric charge of the flavour deciding the sign of $S$. The emergence of a strong magnetic field ($B$) in the non-central collisions at heavy-ion collider experiments motivates us to study the effect of $B$ on Seebeck effect. The strong $B$ affects $S$ in multifold ways, via : a) modification of phase-space due to the dimensional reduction, b) dispersion relation in lowest Landau level (occupation probability), and c) relaxation-time. We find that a strong $B$ not only decreases the magnitudes of $S$'s of individual species, it also flips their signs. This leads to a faster reduction of the magnitude of $S$ of the medium than its counterpart at $B=0$. We then explore how the interactions among partons in perturbative thermal QCD in the quasiparticle framework affect Seebeck effect, where we find that even in strong B, there is no more a flip of the sign of $S$ for individual species and an enhancement of the magnitudes of $S$ of individual species as well as that of the medium, compared to current quark mass description at either $B=0$ or $B\ne 0$.

    ↳ nucl-thcond-mat.mes-hallhep-phPRD(2020)·25 citations
25. 25*

    Probing Cosmic-Ray Accelerated Light Dark Matter with IceCube

    Gang Guo🇹🇼 · Yue-Lin Sming Tsai🇨🇳 · Meng-Ru Wu🇹🇼

    The direct detection of particle dark matter through its scattering with nucleons is of fundamental importance to understand the nature of DM. In this work, we propose that the high-energy neutrino detectors like IceCube can be used to uniquely probe the DM-nucleon cross-section for high-energy DM of $\sim$ PeV, up-scattered by the high-energy cosmic rays. We derive for the first time strong constraints on the DM-nucleon cross-section down to $\sim 10^{-32}$ cm${}^2$ at this energy scale for sub-GeV DM candidates. Such independent probe at energy scale far exceeding other existing direct detection experiments can therefore provide useful insights complementary to other searches.

    ↳ astro-ph.HEhep-exhep-phJCAP(2020)·40 citations
26. 26*

    Obscured $pp$-channel neutrino sources

    Matthias Vereecken🇧🇪 · Krijn D. de Vries🇧🇪

    We explore the possibility that the astrophysical neutrinos are produced in $pp$-interactions with a gas cloud near the source acting as a beam dump, which is sufficiently dense to significantly attenuate the associated gamma-ray flux through pair-production on this gas. In this way, such sources could potentially supply the astrophysical neutrino flux whilst avoiding the existing constraints on the non-blazar contribution to the extragalactic gamma-ray background. After defining our model, we implement a Monte Carlo simulation and apply this to different scenarios. First, we investigate a set of active galaxies which exhibit signs of obscuration. We find that, currently, the expected neutrino flux from these objects in our model is below the existing exclusion limits, but can already constrain the amount of protons accelerated in such sources. Second, we investigate the diffuse neutrino flux generated by a population of obscured sources. We find that such a population can indeed alleviate the tension with the extragalactic background light. We discuss the possibility that ultra-luminous infrared galaxies represent such a source class.

    ↳ astro-ph.HEhep-ph10 citations
27. 27*

    Stable and causal relativistic Navier-Stokes equations

    Raphael E. Hoult🇨🇦 · Pavel Kovtun🇨🇦

    Relativistic Navier-Stokes equations express the conservation of the energy-momentum tensor and the particle number current in terms of the local hydrodynamic variables: temperature, fluid velocity, and the chemical potential. We show that the viscous-fluid equations are stable and causal if one adopts suitable non-equilibrium definitions of the hydrodynamic variables.

    ↳ hep-thgr-qchep-phJHEP(2020)·172 citations
28. 28*

    Enhancing quantum vacuum signatures with tailored laser beams

    Felix Karbstein🇩🇪 · Elena A. Mosman🇷🇺

    We demonstrate that tailored laser beams provide a powerful means to make quantum vacuum signatures in strong electromagnetic fields accessible in experiment. Typical scenarios aiming at the detection of quantum vacuum nonlinearities at the high-intensity frontier envision the collision of focused laser pulses. The effective interaction of the driving fields mediated by vacuum fluctuations gives rise to signal photons encoding the signature of quantum vacuum nonlinearity. Isolating a small number of signal photons from the large background of the driving laser photons poses a major experimental challenge. The main idea of the present work is to modify the far-field properties of a driving laser beam to exhibit a field-free hole in its center, thereby allowing for an essentially background free measurement of the signal scattered in the forward direction. Our explicit construction makes use of a peculiar far-field/focus duality.

    ↳ quant-phhep-phphysics.opticsPRD(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.