The ATLAS Collaboration has come up with the first search for semi-visible jets, looking for them in a basic production mode where 2 protons communicate by exchanging an intermediate particle, which is then converted into 2 jets.
The ATLAS Collaboration has performed the very first search for semi-visible jets, a possible signature for the presence of dark matter particles. Semi-visible jets would occur when dark quarks decay partly to Standard-Model quarks and partly to steady dark hadrons (the “invisible portion”). Given that they are produced in sets, typically along with additional Standard-Model jets, the missing out on energy emerges when all the jets are not completely stabilized. As the ATLAS experiment continues to grow its mammoth dataset, it will provide new opportunities for exploration and new choices to extend the search for semi-visible jets.
Figure 1: The data, background and 6 predicted signal circulations covering a representative arbitrator mass and undetectable portion variety are overlaid for the azimuthal angular distinction between the two semi-visible jets candidates. Exceptional agreement between information and background is observed. Credit: ATLAS Collaboration/CERN
This makes searches for semi-visible jets very difficult, as this event signature can likewise develop due to mis-measured jets in the detector. To do this, they focused on a couple of observables: the uniqueness of the alignment and magnitude of transverse momentum, and the angle in between the semi-visible jets.
After representing all the Standard-Model processes adding to this occasion topology, researchers discovered no hint of semi-visible jets. As can be seen from Figure 1, which reveals the angular difference between the 2 semi-visible jet candidates, the information follows the Standard-Model background shape. Dark-matter signals were anticipated to have a slightly different shape.
The search for semi-visible jets very tough, as its occasion signature can also develop due to mis-measured jets in the detector. How did ATLAS scientists overcome this challenge?
This unique result sets the very first limits on this particular semi-visible-jet production scenario, revealed in Figure 2 as functions of both the mediator mass and the undetectable fraction. The search is more sensitive at intermediate values of the undetectable fraction, and omits conciliator masses up to 2.7 TeV. Scientists were likewise able to report the variety of information occasions observed corresponding to the event selection requirements. This sets crucial groundwork for future look for dark matter, enabling physicists to construct semi-visible-jet designs that take into consideration the existing constraints on this signature.
Figure 2: The expected and observed exclusion shapes for semi-visible jets signal as a function of arbitrator mass on the x-axis, and the unnoticeable fraction on the y-axis. Arbitrator masses on the left-hand side of the red solid line are left out for the given undetectable fraction. Credit: ATLAS Collaboration/CERN
Theres still a lot left to check out! ATLAS scientists plan to methodically study all possible signatures from the strong dark sector landscape, which may consist of exposed signatures like the one thought about in this search. As the ATLAS experiment continues to grow its massive dataset, it will provide brand-new opportunities for exploration and new alternatives to extend the search for semi-visible jets.
The ATLAS Collaboration originated the look for semi-visible jets, a prospective dark matter signature developing from dark quarks and gluons in a highly interacting dark sector. In spite of the difficulties and no direct findings, this unique research sets the very first limits on semi-visible jet production, paving the way for more nuanced dark matter searches in the future.
What occurs if dark-matter particles are produced inside a jet of Standard-Model particles? This results in an unique detector signature called semi-visible jets! The ATLAS Collaboration has developed the very first search for semi-visible jets, searching for them in a basic production mode where 2 protons interact by exchanging an intermediate particle, which is then transformed into 2 jets.
The elusive nature of dark matter remains one of the biggest secrets in particle physics. The majority of the searches have up until now tried to find events where a “weakly connecting” dark-matter particle is produced together with a known Standard-Model particle. Given that the dark-matter particle can not be seen by the ATLAS detector, researchers look for an imbalance of transverse momentum (or “missing out on energy”).
The ATLAS Collaboration has performed the first search for semi-visible jets, a possible signature for the existence of dark matter particles. These are assumed to take place when two protons interact, generating an intermediate particle that then changes into two jets. Credit: ATLAS Collaboration/CERN
Some theoretical models forecast a “strongly engaging” dark sector, with dark quarks and gluons as reproductions of Standard-Model quarks and gluons. Semi-visible jets would emerge when dark quarks decay partly to Standard-Model quarks and partially to stable dark hadrons (the “invisible fraction”). Considering that they are produced in sets, generally together with additional Standard-Model jets, the missing energy occurs when all the jets are not completely balanced. The instructions of the missing energy is often lined up with among the semi-visible jets, as can be seen in case display screen above.