Thu·May 13, 2021Thursday·May 13, 2021

1. 01*

   Physical characteristics of glasma from the earliest stage of relativistic heavy ion collisions

   Margaret E. Carrington🇨🇦 · Alina Czajka🇵🇱 · Stanislaw Mrówczyński🇵🇱

   We present analytic results that describe the gluon field, or glasma, at very early times after a collision of relativistic heavy ions at proper time $\tau =0$. We use a Colour Glass Condensate approach, and perform an expansion in $\tau$. The full details of our method are described in our previous paper [1]. In this paper we present an analysis of various physical quantities that can be obtained from the energy-momentum tensor. We show that the expansion to order ${\tau }^6$ can be trusted to about $\tau =0.05$ fm. For times small enough that the expansion converges, the transverse and longitudinal pressures move towards their equilibrium values of one third of the energy density. The Fourier coefficients of the azimuthal flow are larger than expected, which contradicts the usual assumption that anisotropy is mostly generated during the hydrodynamic evolution of the plasma. We find a significant correlation between the elliptic flow coefficient and the eccentricity, which indicates that the spatial asymmetry introduced by the initial geometry is effectively transmitted to the azimuthal distribution of the gluon momentum field, even at very early times. This result is interesting because correlations of this kind are characteristic of the onset of hydrodynamic behaviour. We show that the angular momentum of the glasma is orders of magnitude smaller than the angular momentum of the initial system of ions colliding with non-zero impact parameter. This indicates that most of the angular momentum carried by the valence quarks is not transmitted to the glasma, and contradicts the picture of a rapidly rotating initial glasma state that has been proposed by several authors, but agrees with the current lack of experimental evidence for a significant polarization effect of the hyperons and vector mesons produced in heavy ion collisions at the highest accessible energies.

   hep-phnucl-thPRC(2022)·30 citations
2. 02*

   One-loop electroweak radiative corrections to charged lepton pair production in photon-photon collisions

   Mehmet Demirci🇹🇷 · M. Fauzi Mustamin🇹🇷

   We provide high-precision predictions for muon-pair and tau-pair productions in a photon-photon collision by considering a complete set of one-loop-level scattering amplitudes, i.e., electroweak (EW) corrections together with soft and hard QED radiation. Accordingly, we present a detailed numerical discussion with particular emphasis on the pure QED corrections as well as genuinely weak corrections. The effects of angular and initial beam polarisation distributions on production rates are also discussed. An improvement is observed by a factor of two with oppositely polarized photons. Our results indicate that the one-loop EW radiative corrections enhance the Born cross section and the total relative correction is typically about ten percent for both production channels. It appears that the full EW corrections to $\gamma \gamma \to {\ell }^{-}{\ell }^{+}$ are required to match a percent level accuracy.

   hep-phhep-thPRD(2021)·8 citations
3. 03*

   Neutrino constraints to scotogenic dark matter interacting in the Sun

   Thede de Boer🇩🇪 · Raffaela Busse🇩🇪 · Alexander Kappes🇩🇪 · Michael Klasen🇩🇪 · Sybrand Zeinstra🇩🇪

   Radiative seesaw models have the attractive property of providing dark matter candidates in addition to generation of neutrino masses. Here we present a study of neutrino signals from the annihilation of dark matter particles which have been gravitationally captured in the Sun, in the framework of the scotogenic model. We compute expected event rates in the IceCube detector in its 86-string configuration. As fermionic dark matter does not accumulate in the Sun, we study the case of scalar dark matter, with a scan over the parameter space. Due to a naturally small mass splitting between the two neutral scalar components, inelastic scattering processes with nucleons can occur. We find that for small mass splittings, the model yields very high event rates. If a detailed analysis at IceCube can exclude these parameter points, our findings can be translated into a lower limit on one of the scalar couplings in the model. For larger mass splittings only the elastic case needs to be considered. We find that in this scenario the XENON1T limits exclude all points with sufficiently large event rates.

   hep-ph2 citations
4. 04*

   W-exchange contributions in hadronic decays of bottom baryon ${\Lambda }_b$

   Fayyazuddin🇵🇰

   The nonleptonic decays ${\Lambda }_b\to {\Sigma }_c^{\ast -}{\pi }^{+},{\Xi }_c^{\ast 0}{K}^0$ and ${\Lambda }_b\to {\Delta }^0{D}^0,{\Sigma }^{\ast -}{D}_0^{+}$ are studied. In addition, the decays ${\Lambda }_b\to {\Xi }_c^0{K}^0,{\Sigma }^{-}{D}_s^{+}$ are analyzed. For all these decays the dominant contribution comes from $W-$exchange, and for the decay ${\Lambda }_b\to {\Lambda }_c^{+}{\pi }^{-}$, in addition to factorization, baryon pole contribution to the $p$-wave (parity conserving) decay amplitude $B$ is discussed.

   hep-phhep-ex0 citations
5. 05*

   The phase structure of two color QCD and charged pion condensation phenomenon

   T. G. Khunjua🇬🇪 · K. G. Klimenko🇷🇺 · R. N. Zhokhov🇷🇺

   The phase structure of dense quark matter in the two color case has been investigated with nonzero baryon ${\mu }_B$, isospin ${\mu }_I$ and chiral isospin ${\mu }_{I5}$ chemical potentials. %in the framework of Nambu--Jona-Lasinio model with quark-antiquark and quark-quark interaction channels. It has been shown in the mean-field approximation that there exist three dualities, one of them between phases with spontaneous chiral symmetry breaking and condensation of charged pions, found in the three color case. The other two dual symmetries between the phase with condensation of charged pions and the phase with diquark condensation and between chiral symmetry breaking and diquark condensation phenomena. It has been demonstrated that due to the duality properties the phase diagram is extremely symmetric and the whole phase diagram in two color case can be obtained just by dualities from the phase structure of three color case. This shows that the dualities are rather usefull tool. It is shown that chiral imbalance generates charged pion condensation phenomenon in conditions of matter in neutron stars, i. e. electrically neutral and $\beta$-equilibrated dense quark matter. And that diquark condensation does not prohibit the generation of the charged PC phase by chiral imbalance at least in the two color case.

   hep-phhep-thPhys.Part.Nucl.(2022)·7 citations
6. 06*

   Search for dark matter using sub-PeV $\mathbf{\gamma }$-rays observed by Tibet AS${}_{\mathbf{\gamma }}$

   Tarak Nath Maity🇮🇳 · Akash Kumar Saha🇮🇳 · Abhishek Dubey🇮🇳 · Ranjan Laha🇮🇳

   The discovery of diffuse sub-PeV gamma-rays by the Tibet AS${}_{\gamma }$ Collaboration promises to revolutionize our understanding of the high-energy astrophysical universe. It has been shown that these data broadly agree with prior theoretical expectations. We study the impact of this discovery on a well-motivated new physics scenario: PeV-scale decaying dark matter (DM). Considering a wide range of final states in DM decay, a number of DM density profiles, and numerous astrophysical background models, we find that these data provide the most stringent limit on DM lifetime for various Standard Model final states. In particular, we find that the strongest constraints are derived for DM masses in between a few PeV to a few tens of PeV. Near-future data of these high-energy gamma-rays can be used to discover PeV-scale decaying DM.

   hep-phastro-ph.COastro-ph.GAastro-ph.HE+1PRD(2022)·39 citations
7. 07*

   Baryogenesis from a CP-violating inflation

   Venus Keus🇫🇮

   We introduce the novel phenomena of CP-violating inflation in the frameworks of a 3-Higgs doublet model where the inflaton doublets have a non-minimal coupling to gravity. We allow for this coupling to be complex, thereby introducing CP-violation - a necessary source of the baryon asymmetry - in the inflaton couplings. We investigate the inflationary dynamics of such a framework and the inflaton decay in the reheating phase. We discuss how the CP-violation of the model is imprinted on the particle asymmetries.

   hep-phgr-qc1 citation
8. 08*

   Milli-Magnetic Monopole Dark Matter and the Survival of Galactic Magnetic Fields

   Michael L. Graesser🇺🇸 · Ian M. Shoemaker🇺🇸 · Natalia Tapia Arellano🇺🇸

   Dark sectors with Abelian gauge symmetries can interact with ordinary matter via kinetic mixing. In such scenarios, magnetic monopoles of a broken dark $U(1)$ will appear in our sector as confined milli-magnetically charged objects under ordinary electromagnetism. Halo ellipticity constraints are shown to significantly bound the strength of dark magnetic Coulomb monopole interactions. The bound monopole ground state, which in vacuum is stable and has no magnetic charge or moment, is shown to become quantum mechanically unstable in the presence of an external, ordinary magnetic field. If these states contribute sizably to the local dark matter density, they can extract significant energy from the galactic magnetic field if their decay occurs on a galactic timescale or less. We revise and extend this "Parker Bound" on galactic magnetic energy loss to milli-monopoles which leads to the strongest existing constraints on these states, satisfying our halo ellipticity bounds, over a wide range of monopole masses.

   hep-phastro-ph.COastro-ph.GAhep-thJHEP(2022)·18 citations
9. 09*

   Spontaneous breaking of the Peccei-Quinn symmetry during warm inflation

   João G. Rosa🇵🇹 · Luís B. Ventura🇵🇹

   We show that, for values of the axion decay constant parametrically close to the GUT scale, the Peccei-Quinn phase transition may naturally occur during warm inflation. This results from interactions between the Peccei-Quinn scalar field and the ambient thermal bath, which is sustained by the inflaton field through dissipative effects. It is therefore possible for the axion field to appear as a dynamical degree of freedom only after observable CMB scales have become super-horizon, thus avoiding the large-scale axion isocurvature perturbations that typically plague such models. This nevertheless yields a nearly scale-invariant spectrum of axion isocurvature perturbations on small scales, with a density contrast of up to a few percent, which may have a significant impact on the formation of gravitationally-bound axion structures such as mini-clusters.

   hep-phastro-ph.COgr-qcPRD(2026)·10 citations
10. 10*

    Resonant contributions to inclusive nucleon structure functions from exclusive meson electroproduction data

    A. N. Hiller Blin🇺🇸 · W. Melnitchouk🇺🇸 · V. I. Mokeev🇺🇸 · V. D. Burkert🇺🇸 · V. V. Chesnokov🇷🇺 · A. Pilloni🇮🇹 · A. P. Szczepaniak🇺🇸

    Nucleon resonance contributions to the inclusive proton $F_2$ and $F_L$ structure functions are computed from resonance electroexcitation amplitudes in the mass range up to 1.75 GeV extracted from CLAS exclusive meson electroproduction data. Taking into account for the first time quantum interference effects, the resonance contributions are compared with inclusive proton structure functions evaluated from $(e,e^{\prime }X)$ cross section data and the longitudinal to transverse cross section ratio. Contributions from isospin-1/2 and 3/2 resonances remain substantial over the entire range of photon virtualities $Q^2\lesssim 4$ GeV${}^2$, where their electroexcitation amplitudes have been obtained, and their $Q^2$ evolution displays pronounced differences in the first, second and third resonance regions. We compare the structure functions in the resonance region with those computed from parton distributions fitted to deep-inelastic scattering data, and extrapolated to the resonance region, providing new quantitative assessments of quark-hadron duality in inclusive electron-proton scattering.

    hep-phhep-exPRC(2021)·24 citations
11. 11*

    New Physics Through Drell Yan SMEFT Measurements at NLO

    Sally Dawson🇺🇸 · Pier Paolo Giardino🇪🇸

    Drell Yan production is a sensitive probe of new physics and as such has been calculated to high order in both the electroweak and QCD sectors of the Standard Model, allowing for precision comparisons between theory and data. Here we extend these calculations to the Standard Model Effective field theory (SMEFT) and present the NLO QCD and electroweak contributions to the neutral Drell Yan process that are linear in the Wilson coefficients of the SMEFT theory.

    hep-phPRD(2021)·47 citations
12. 12*

    Is the Chiral Magnetic Effect fast enough?

    Jewel K. Ghosh🇧🇩 · Sebastian Grieninger🇪🇸 · Karl Landsteiner🇪🇸 · Sergio Morales-Tejera🇪🇸

    It depends: While we find within holography that the lifetime of the magnetic field for collider energies like the ones achieved at RHIC is long enough to build up the chiral magnetic current, the lifetime of the magnetic field at LHC seems to be too short. We study the real time evolution of the chiral magnetic effect out-of-equilibrium in strongly coupled holographic gauge theories. We consider the backreaction of the magnetic field onto the geometry and monitor pressure and chiral magnetic current. Our findings show that generically at small magnetic field the pressure builds up faster than the chiral magnetic current whereas at strong magnetic field the opposite is true. At large charge we also find that equilibration is delayed significantly due to long lived oscillations. We also match the parameters of our model to QCD parameters and draw lessons of possible relevance to the realization of the chiral magnetic effect in heavy ion collisions. In particular, we find an equilibration time of about $\sim 0.35$ fm/c in presence of the chiral anomaly for plasma temperatures of order $T\sim 300-400$ MeV.

    hep-phcond-mat.str-elhep-thnucl-ex+1PRD(2021)·26 citations
13. 13*

    Challenges for Inflaton Dark Matter

    Oleg Lebedev🇫🇮 · Jong-Hyun Yoon🇫🇮

    We examine an intriguing possibility that a single field is responsible for both inflation and dark matter, focussing on the minimal set-up where inflation is driven by a scalar coupling to curvature. We study in detail the reheating process in this framework, which amounts mainly to particle production in a quartic potential, and distinguish thermal and non-thermal dark matter options. In the non-thermal case, the reheating is impeded by backreaction and rescattering, making this possibility unrealistic. On the other hand, thermalized dark matter is viable, yet the unitarity bound forces the inflaton mass into a narrow window close to half the Higgs mass.

    hep-phastro-ph.COastro-ph.HEPLB(2021)·22 citations
14. 14*

    Searching for Flavor-Violating ALPs in Higgs Decays

    Hooman Davoudiasl🇺🇸 · Roman Marcarelli🇺🇸 · Nicholas Miesch🇺🇸 · Ethan T. Neil🇺🇸

    Pseudo-scalar particles, often referred to as axion-like-particles (ALPs), arise in a variety of theoretical contexts. The phenomenology of such states is typically studied assuming flavor-conserving interactions, yet they can in principle have flavor-violating (FV) couplings to fermions. We consider this general possibility, focusing on models where the ALP has non-negligible coupling to the Standard Model Higgs boson $h$. For a lepton FV ALP $a$ of mass $m_a\gtrsim 2$ GeV, $a\to \tau \ell$, where $\ell \ne \tau$ is a charged lepton, could have $\mathcal{O}(1)$ branching fraction, leading to potentially detectable $h\to aa\to \tau \ell \tau \ell$ at the LHC and its future program. We examine this possibility, in light of existing bounds on FV processes, in a general effective theory. We obtain constraints on the effective couplings from both prompt and long-lifetime searches at the LHC; some projections for envisioned measurements are also provided. The implications of the recently announced first results of the muon $g-2$ measurement at Fermilab for the ALP interactions considered in our work are also briefly discussed.

    hep-phPRD(2021)·25 citations
15. 15*

    Probing nuclear quadrupole deformation from correlation of elliptic flow and transverse momentum in heavy ion collisions

    Jiangyong Jia🇺🇸 · Shengli Huang🇺🇸 · Chunjian Zhang🇺🇸

    In heavy ion collisions, elliptic flow $v_2$ and radial flow, characterized by event-wise average transverse momentum $[p_{\mathrm{T}}]$, are related to the shape and size of the overlap region, which are sensitive to the shape of colliding atomic nuclei. The Pearson correlation coefficient between $v_2$ and $[p_{\mathrm{T}}]$, ${\rho }_2$, was found to be particularly sensitive to the quadrupole deformation parameter $\beta$ that is traditionally measured in low energy experiments. Built on earlier insight that the prolate deformation $\beta >0$ reduces the ${\rho }_2$ in ultra-central collisions (UCC), we show that the prolate deformation $\beta <0$ enhances the value of ${\rho }_2$. As $\beta >0$ and $\beta <0$ are the two extremes of triaxiality, the strength and sign of $v_2^2-[p_{\mathrm{T}}]$ correlation can be used to provide valuable information on the triaxiality of the nucleus. Our study provide further arguments for using the hydrodynamic flow as a precision tool to directly image the deformation of the atomic nuclei at extremely short time scale ($<10^{-24}$s).

    ↳ nucl-thhep-phnucl-exphysics.atom-phPRC(2022)·57 citations
16. 16*

    A combined fit to the Higgs Branching Ratios at ILD

    Jonas Kunath🇫🇷 · Fabricio Jimenez Morales🇫🇷 · Jean-Claude Brient🇫🇷 · Vincent Boudry🇫🇷

    Higgs decay branching ratios at future Higgs factories can be measured by directly exploiting class numeration. Given the clean environment at a lepton collider, it is possible to build an event sample highly enriched in Higgs bosons and essentially unbiased for any decay mode. The sample can be partitioned into categories using event properties linked to the expected Higgs decay modes. The counts per category are used to fit the Higgs branching ratios in a model independent way. The result of the fit is the set of branching ratios, independent from a Higgs production mode measurement. We present a simplified study on simulated data for the International Linear Detector (ILD) at the International Linear Collider (ILC) at 250 GeV center-of-mass energy.

    ↳ hep-exhep-ph2 citations
17. 17*

    The neutrino gravitational memory from a core collapse supernova: phenomenology and physics potential

    Mainak Mukhopadhyay🇺🇸 · Carlos Cardona🇺🇸 · Cecilia Lunardini🇺🇸

    General Relativity predicts that the passage of matter or radiation from an asymmetrically-emitting source should cause a permanent change in the local space-time metric. This phenomenon, called the \emph{gravitational memory effect}, has never been observed, however supernova neutrinos have long been considered a promising avenue for its detection in the future. With the advent of deci-Hertz gravitational wave interferometers, observing the supernova neutrino memory will be possible, with important implications for multimessenger astronomy and for tests of gravity. In this work, we develop a phenomenological (analytical) toy model for the supernova neutrino memory effect, which is overall consistent with the results of numerical simulations. This description is then generalized to several case studies of interest. We find that, for a galactic supernova, the dimensionless strain, $h(t)$, is of order $\sim 10^{-22}-10^{-21}$, and develops over a typical time scale that varies between $\sim 0.1-10$ s, depending on the time-evolution of the anisotropy of the neutrino emission. The characteristic strain, $h_c(f)$, has a maximum at a frequency $f_{max}\sim \mathcal{O}(10^{-1})-\mathcal{O}(1)$ Hz. The detailed features of the time- and frequency-structure of the memory strain will inform us of the matter dynamics near the collapsed core, and allow to distinguish between different stellar collapse scenarios. Next generation gravitational wave detectors like DECIGO and BBO will be sensitive to the neutrino memory effect for supernovae at typical galactic distances and beyond; with Ultimate DECIGO exceeding a detectability distance of 10 Mpc.

    ↳ astro-ph.HEgr-qchep-phJCAP(2021)·36 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.