HANOVER, N.H. >> Three Dartmouth College professors whose research had included studies of sexual desire and attractiveness have been put on paid leave while a criminal investigation of alleged sexual misconduct is carried out, authorities said today.

Attorney General Gordon J. MacDonald of New Hampshire said his office was part of a joint criminal investigation by five law enforcement agencies into allegations of “serious misconduct” by the professors, all tenured faculty members of the Department of Psychological and Brain Sciences. The professors’ access to the Dartmouth campus here has been restricted.

Details of the allegations were not released, but MacDonald’s statement said the criminal investigation arose after an inquiry to college officials by the college newspaper, The Dartmouth, which reported last week that the professors had disappeared from their campus posts and flyers had been posted around campus inquiring as to their whereabouts.

At that time, the college announced that it was conducting its own investigation.

News of a criminal investigation with no additional explanation to the 4,300 undergraduate and 2,000 graduate students left some of them bewildered.

Several students hanging out at the Collis student center Tuesday said they were surprised by the allegations because all three professors were established and respected intellectuals in their fields. They were also popular with students.

Maggie Pizzo, a junior math major, said she was concerned that the professors had been put on paid leave as opposed to suspended without pay.

“By paying them, it seems to be condoning the acts,” whatever they were, she said, as well as being “disrespectful” toward whoever brought the allegation of harassment.

“It seems to minimize the whole thing,” Pizzo said.

One female student, a junior, said she felt “pretty uncomfortable” that the administration had apparently known about the allegations for some time and was only addressing it publicly now.

“It’s creepy, even though we don’t really know what it is,” the junior, who declined to give her name, said. “People have been pretty weirded out by this.”

She said that graduate students were filling in for the banned professors and that some students felt shortchanged by not being taught by the scholars they had signed up for.

In a separate statement today, the president of Dartmouth, Philip J. Hanlon, said the university was cooperating with the criminal investigations of the three professors, identified by the newspaper as Todd F. Heatherton, William M. Kelley and Paul J. Whalen.

Heatherton leads a center for social brain sciences and, according to the college’s website, conducts research in social behavior focusing on self-regulation, self-esteem and self-referential processing. Kelley’s work focuses on memory and self-regulation, according to the website.

The two were among authors in 2012 on research on how images of food and sex affect the brain. As part of the research, 58 female college freshmen underwent brain scans shortly after arrival on campus while viewing 80 images each of animals, environmental scenes, food items, and people — some involved in sexual scenes or consuming alcohol. Six months later, they were called back to the lab, weighed, and questioned on their sexual behavior.

The study, published in the Journal Neuroscience, concluded that the students whose brains reacted to food and sexual stimuli gained more weight and reported greater sexual desire in the follow-up questioning. The study was supported by the National Institute on Drug Abuse. Whalen was listed as having assisted in that study.

Whalen, a popular professor on campus who delivered a TedXDartmouth talk, runs the Whalen Lab, which conducts research on a part of the brain known as the amygdala. Among his published research papers was a collaboration with Kelley and Heatherton and others on the question of whether the brains of men and women react differently to attractive facial features in members of the opposite sex. That paper was published in 2008 in the Journal of Cognitive Neuroscience.

None of the professors could be reached immediately for comment.

“I want to say in the most emphatic way possible that sexual misconduct and harassment are unacceptable and have no place at Dartmouth,” Hanlon said. “Such acts harm us as individuals and as members of the community.”

Hanlon’s statement referred the campus community to Dartmouth’s “sexual respect” website.